Restoring authorship annotation for <[email protected]>. Commit 1 of 2.

1 files changed, 3728 insertions, 3728 deletions

diff --git a/contrib/libs/llvm12/lib/CodeGen/MachineScheduler.cpp b/contrib/libs/llvm12/lib/CodeGen/MachineScheduler.cpp
index 8d51bb26103..48d9e5c2232 100644
--- a/contrib/libs/llvm12/lib/CodeGen/MachineScheduler.cpp
+++ b/contrib/libs/llvm12/lib/CodeGen/MachineScheduler.cpp
@@ -1,134 +1,134 @@
-//===- MachineScheduler.cpp - Machine Instruction Scheduler ---------------===//
-//
-// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-// See https://llvm.org/LICENSE.txt for license information.
-// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-//
-//===----------------------------------------------------------------------===//
-//
-// MachineScheduler schedules machine instructions after phi elimination. It
-// preserves LiveIntervals so it can be invoked before register allocation.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/CodeGen/MachineScheduler.h"
-#include "llvm/ADT/ArrayRef.h"
-#include "llvm/ADT/BitVector.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/PriorityQueue.h"
-#include "llvm/ADT/STLExtras.h"
-#include "llvm/ADT/SmallVector.h"
+//===- MachineScheduler.cpp - Machine Instruction Scheduler ---------------===// 
+// 
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 
+// See https://llvm.org/LICENSE.txt for license information. 
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 
+// 
+//===----------------------------------------------------------------------===// 
+// 
+// MachineScheduler schedules machine instructions after phi elimination. It 
+// preserves LiveIntervals so it can be invoked before register allocation. 
+// 
+//===----------------------------------------------------------------------===// 
+ 
+#include "llvm/CodeGen/MachineScheduler.h" 
+#include "llvm/ADT/ArrayRef.h" 
+#include "llvm/ADT/BitVector.h" 
+#include "llvm/ADT/DenseMap.h" 
+#include "llvm/ADT/PriorityQueue.h" 
+#include "llvm/ADT/STLExtras.h" 
+#include "llvm/ADT/SmallVector.h" 
 #include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/iterator_range.h"
-#include "llvm/Analysis/AliasAnalysis.h"
-#include "llvm/CodeGen/LiveInterval.h"
-#include "llvm/CodeGen/LiveIntervals.h"
-#include "llvm/CodeGen/MachineBasicBlock.h"
-#include "llvm/CodeGen/MachineDominators.h"
-#include "llvm/CodeGen/MachineFunction.h"
-#include "llvm/CodeGen/MachineFunctionPass.h"
-#include "llvm/CodeGen/MachineInstr.h"
-#include "llvm/CodeGen/MachineLoopInfo.h"
-#include "llvm/CodeGen/MachineOperand.h"
-#include "llvm/CodeGen/MachinePassRegistry.h"
-#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/CodeGen/Passes.h"
-#include "llvm/CodeGen/RegisterClassInfo.h"
-#include "llvm/CodeGen/RegisterPressure.h"
-#include "llvm/CodeGen/ScheduleDAG.h"
-#include "llvm/CodeGen/ScheduleDAGInstrs.h"
-#include "llvm/CodeGen/ScheduleDAGMutation.h"
-#include "llvm/CodeGen/ScheduleDFS.h"
-#include "llvm/CodeGen/ScheduleHazardRecognizer.h"
-#include "llvm/CodeGen/SlotIndexes.h"
-#include "llvm/CodeGen/TargetFrameLowering.h"
-#include "llvm/CodeGen/TargetInstrInfo.h"
-#include "llvm/CodeGen/TargetLowering.h"
-#include "llvm/CodeGen/TargetPassConfig.h"
-#include "llvm/CodeGen/TargetRegisterInfo.h"
-#include "llvm/CodeGen/TargetSchedule.h"
-#include "llvm/CodeGen/TargetSubtargetInfo.h"
-#include "llvm/Config/llvm-config.h"
-#include "llvm/InitializePasses.h"
-#include "llvm/MC/LaneBitmask.h"
-#include "llvm/Pass.h"
-#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Compiler.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/GraphWriter.h"
-#include "llvm/Support/MachineValueType.h"
-#include "llvm/Support/raw_ostream.h"
-#include <algorithm>
-#include <cassert>
-#include <cstdint>
-#include <iterator>
-#include <limits>
-#include <memory>
-#include <string>
-#include <tuple>
-#include <utility>
-#include <vector>
-
-using namespace llvm;
-
-#define DEBUG_TYPE "machine-scheduler"
-
+#include "llvm/ADT/iterator_range.h" 
+#include "llvm/Analysis/AliasAnalysis.h" 
+#include "llvm/CodeGen/LiveInterval.h" 
+#include "llvm/CodeGen/LiveIntervals.h" 
+#include "llvm/CodeGen/MachineBasicBlock.h" 
+#include "llvm/CodeGen/MachineDominators.h" 
+#include "llvm/CodeGen/MachineFunction.h" 
+#include "llvm/CodeGen/MachineFunctionPass.h" 
+#include "llvm/CodeGen/MachineInstr.h" 
+#include "llvm/CodeGen/MachineLoopInfo.h" 
+#include "llvm/CodeGen/MachineOperand.h" 
+#include "llvm/CodeGen/MachinePassRegistry.h" 
+#include "llvm/CodeGen/MachineRegisterInfo.h" 
+#include "llvm/CodeGen/Passes.h" 
+#include "llvm/CodeGen/RegisterClassInfo.h" 
+#include "llvm/CodeGen/RegisterPressure.h" 
+#include "llvm/CodeGen/ScheduleDAG.h" 
+#include "llvm/CodeGen/ScheduleDAGInstrs.h" 
+#include "llvm/CodeGen/ScheduleDAGMutation.h" 
+#include "llvm/CodeGen/ScheduleDFS.h" 
+#include "llvm/CodeGen/ScheduleHazardRecognizer.h" 
+#include "llvm/CodeGen/SlotIndexes.h" 
+#include "llvm/CodeGen/TargetFrameLowering.h" 
+#include "llvm/CodeGen/TargetInstrInfo.h" 
+#include "llvm/CodeGen/TargetLowering.h" 
+#include "llvm/CodeGen/TargetPassConfig.h" 
+#include "llvm/CodeGen/TargetRegisterInfo.h" 
+#include "llvm/CodeGen/TargetSchedule.h" 
+#include "llvm/CodeGen/TargetSubtargetInfo.h" 
+#include "llvm/Config/llvm-config.h" 
+#include "llvm/InitializePasses.h" 
+#include "llvm/MC/LaneBitmask.h" 
+#include "llvm/Pass.h" 
+#include "llvm/Support/CommandLine.h" 
+#include "llvm/Support/Compiler.h" 
+#include "llvm/Support/Debug.h" 
+#include "llvm/Support/ErrorHandling.h" 
+#include "llvm/Support/GraphWriter.h" 
+#include "llvm/Support/MachineValueType.h" 
+#include "llvm/Support/raw_ostream.h" 
+#include <algorithm> 
+#include <cassert> 
+#include <cstdint> 
+#include <iterator> 
+#include <limits> 
+#include <memory> 
+#include <string> 
+#include <tuple> 
+#include <utility> 
+#include <vector> 
+ 
+using namespace llvm; 
+ 
+#define DEBUG_TYPE "machine-scheduler" 
+ 
 STATISTIC(NumClustered, "Number of load/store pairs clustered");
 
-namespace llvm {
-
-cl::opt<bool> ForceTopDown("misched-topdown", cl::Hidden,
-                           cl::desc("Force top-down list scheduling"));
-cl::opt<bool> ForceBottomUp("misched-bottomup", cl::Hidden,
-                            cl::desc("Force bottom-up list scheduling"));
-cl::opt<bool>
-DumpCriticalPathLength("misched-dcpl", cl::Hidden,
-                       cl::desc("Print critical path length to stdout"));
-
-cl::opt<bool> VerifyScheduling(
-    "verify-misched", cl::Hidden,
-    cl::desc("Verify machine instrs before and after machine scheduling"));
-
-} // end namespace llvm
-
-#ifndef NDEBUG
-static cl::opt<bool> ViewMISchedDAGs("view-misched-dags", cl::Hidden,
-  cl::desc("Pop up a window to show MISched dags after they are processed"));
-
-/// In some situations a few uninteresting nodes depend on nearly all other
-/// nodes in the graph, provide a cutoff to hide them.
-static cl::opt<unsigned> ViewMISchedCutoff("view-misched-cutoff", cl::Hidden,
-  cl::desc("Hide nodes with more predecessor/successor than cutoff"));
-
-static cl::opt<unsigned> MISchedCutoff("misched-cutoff", cl::Hidden,
-  cl::desc("Stop scheduling after N instructions"), cl::init(~0U));
-
-static cl::opt<std::string> SchedOnlyFunc("misched-only-func", cl::Hidden,
-  cl::desc("Only schedule this function"));
-static cl::opt<unsigned> SchedOnlyBlock("misched-only-block", cl::Hidden,
-                                        cl::desc("Only schedule this MBB#"));
-static cl::opt<bool> PrintDAGs("misched-print-dags", cl::Hidden,
-                              cl::desc("Print schedule DAGs"));
-#else
-static const bool ViewMISchedDAGs = false;
-static const bool PrintDAGs = false;
-#endif // NDEBUG
-
-/// Avoid quadratic complexity in unusually large basic blocks by limiting the
-/// size of the ready lists.
-static cl::opt<unsigned> ReadyListLimit("misched-limit", cl::Hidden,
-  cl::desc("Limit ready list to N instructions"), cl::init(256));
-
-static cl::opt<bool> EnableRegPressure("misched-regpressure", cl::Hidden,
-  cl::desc("Enable register pressure scheduling."), cl::init(true));
-
-static cl::opt<bool> EnableCyclicPath("misched-cyclicpath", cl::Hidden,
-  cl::desc("Enable cyclic critical path analysis."), cl::init(true));
-
-static cl::opt<bool> EnableMemOpCluster("misched-cluster", cl::Hidden,
-                                        cl::desc("Enable memop clustering."),
-                                        cl::init(true));
+namespace llvm { 
+ 
+cl::opt<bool> ForceTopDown("misched-topdown", cl::Hidden, 
+                           cl::desc("Force top-down list scheduling")); 
+cl::opt<bool> ForceBottomUp("misched-bottomup", cl::Hidden, 
+                            cl::desc("Force bottom-up list scheduling")); 
+cl::opt<bool> 
+DumpCriticalPathLength("misched-dcpl", cl::Hidden, 
+                       cl::desc("Print critical path length to stdout")); 
+ 
+cl::opt<bool> VerifyScheduling( 
+    "verify-misched", cl::Hidden, 
+    cl::desc("Verify machine instrs before and after machine scheduling")); 
+ 
+} // end namespace llvm 
+ 
+#ifndef NDEBUG 
+static cl::opt<bool> ViewMISchedDAGs("view-misched-dags", cl::Hidden, 
+  cl::desc("Pop up a window to show MISched dags after they are processed")); 
+ 
+/// In some situations a few uninteresting nodes depend on nearly all other 
+/// nodes in the graph, provide a cutoff to hide them. 
+static cl::opt<unsigned> ViewMISchedCutoff("view-misched-cutoff", cl::Hidden, 
+  cl::desc("Hide nodes with more predecessor/successor than cutoff")); 
+ 
+static cl::opt<unsigned> MISchedCutoff("misched-cutoff", cl::Hidden, 
+  cl::desc("Stop scheduling after N instructions"), cl::init(~0U)); 
+ 
+static cl::opt<std::string> SchedOnlyFunc("misched-only-func", cl::Hidden, 
+  cl::desc("Only schedule this function")); 
+static cl::opt<unsigned> SchedOnlyBlock("misched-only-block", cl::Hidden, 
+                                        cl::desc("Only schedule this MBB#")); 
+static cl::opt<bool> PrintDAGs("misched-print-dags", cl::Hidden, 
+                              cl::desc("Print schedule DAGs")); 
+#else 
+static const bool ViewMISchedDAGs = false; 
+static const bool PrintDAGs = false; 
+#endif // NDEBUG 
+ 
+/// Avoid quadratic complexity in unusually large basic blocks by limiting the 
+/// size of the ready lists. 
+static cl::opt<unsigned> ReadyListLimit("misched-limit", cl::Hidden, 
+  cl::desc("Limit ready list to N instructions"), cl::init(256)); 
+ 
+static cl::opt<bool> EnableRegPressure("misched-regpressure", cl::Hidden, 
+  cl::desc("Enable register pressure scheduling."), cl::init(true)); 
+ 
+static cl::opt<bool> EnableCyclicPath("misched-cyclicpath", cl::Hidden, 
+  cl::desc("Enable cyclic critical path analysis."), cl::init(true)); 
+ 
+static cl::opt<bool> EnableMemOpCluster("misched-cluster", cl::Hidden, 
+                                        cl::desc("Enable memop clustering."), 
+                                        cl::init(true)); 
 static cl::opt<bool>
     ForceFastCluster("force-fast-cluster", cl::Hidden,
                      cl::desc("Switch to fast cluster algorithm with the lost "
@@ -138,108 +138,108 @@ static cl::opt<unsigned>
     FastClusterThreshold("fast-cluster-threshold", cl::Hidden,
                          cl::desc("The threshold for fast cluster"),
                          cl::init(1000));
-
-// DAG subtrees must have at least this many nodes.
-static const unsigned MinSubtreeSize = 8;
-
-// Pin the vtables to this file.
-void MachineSchedStrategy::anchor() {}
-
-void ScheduleDAGMutation::anchor() {}
-
-//===----------------------------------------------------------------------===//
-// Machine Instruction Scheduling Pass and Registry
-//===----------------------------------------------------------------------===//
-
-MachineSchedContext::MachineSchedContext() {
-  RegClassInfo = new RegisterClassInfo();
-}
-
-MachineSchedContext::~MachineSchedContext() {
-  delete RegClassInfo;
-}
-
-namespace {
-
-/// Base class for a machine scheduler class that can run at any point.
-class MachineSchedulerBase : public MachineSchedContext,
-                             public MachineFunctionPass {
-public:
-  MachineSchedulerBase(char &ID): MachineFunctionPass(ID) {}
-
-  void print(raw_ostream &O, const Module* = nullptr) const override;
-
-protected:
-  void scheduleRegions(ScheduleDAGInstrs &Scheduler, bool FixKillFlags);
-};
-
-/// MachineScheduler runs after coalescing and before register allocation.
-class MachineScheduler : public MachineSchedulerBase {
-public:
-  MachineScheduler();
-
-  void getAnalysisUsage(AnalysisUsage &AU) const override;
-
-  bool runOnMachineFunction(MachineFunction&) override;
-
-  static char ID; // Class identification, replacement for typeinfo
-
-protected:
-  ScheduleDAGInstrs *createMachineScheduler();
-};
-
-/// PostMachineScheduler runs after shortly before code emission.
-class PostMachineScheduler : public MachineSchedulerBase {
-public:
-  PostMachineScheduler();
-
-  void getAnalysisUsage(AnalysisUsage &AU) const override;
-
-  bool runOnMachineFunction(MachineFunction&) override;
-
-  static char ID; // Class identification, replacement for typeinfo
-
-protected:
-  ScheduleDAGInstrs *createPostMachineScheduler();
-};
-
-} // end anonymous namespace
-
-char MachineScheduler::ID = 0;
-
-char &llvm::MachineSchedulerID = MachineScheduler::ID;
-
-INITIALIZE_PASS_BEGIN(MachineScheduler, DEBUG_TYPE,
-                      "Machine Instruction Scheduler", false, false)
-INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
-INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
-INITIALIZE_PASS_DEPENDENCY(SlotIndexes)
-INITIALIZE_PASS_DEPENDENCY(LiveIntervals)
-INITIALIZE_PASS_END(MachineScheduler, DEBUG_TYPE,
-                    "Machine Instruction Scheduler", false, false)
-
-MachineScheduler::MachineScheduler() : MachineSchedulerBase(ID) {
-  initializeMachineSchedulerPass(*PassRegistry::getPassRegistry());
-}
-
-void MachineScheduler::getAnalysisUsage(AnalysisUsage &AU) const {
-  AU.setPreservesCFG();
-  AU.addRequired<MachineDominatorTree>();
-  AU.addRequired<MachineLoopInfo>();
-  AU.addRequired<AAResultsWrapperPass>();
-  AU.addRequired<TargetPassConfig>();
-  AU.addRequired<SlotIndexes>();
-  AU.addPreserved<SlotIndexes>();
-  AU.addRequired<LiveIntervals>();
-  AU.addPreserved<LiveIntervals>();
-  MachineFunctionPass::getAnalysisUsage(AU);
-}
-
-char PostMachineScheduler::ID = 0;
-
-char &llvm::PostMachineSchedulerID = PostMachineScheduler::ID;
-
+ 
+// DAG subtrees must have at least this many nodes. 
+static const unsigned MinSubtreeSize = 8; 
+ 
+// Pin the vtables to this file. 
+void MachineSchedStrategy::anchor() {} 
+ 
+void ScheduleDAGMutation::anchor() {} 
+ 
+//===----------------------------------------------------------------------===// 
+// Machine Instruction Scheduling Pass and Registry 
+//===----------------------------------------------------------------------===// 
+ 
+MachineSchedContext::MachineSchedContext() { 
+  RegClassInfo = new RegisterClassInfo(); 
+} 
+ 
+MachineSchedContext::~MachineSchedContext() { 
+  delete RegClassInfo; 
+} 
+ 
+namespace { 
+ 
+/// Base class for a machine scheduler class that can run at any point. 
+class MachineSchedulerBase : public MachineSchedContext, 
+                             public MachineFunctionPass { 
+public: 
+  MachineSchedulerBase(char &ID): MachineFunctionPass(ID) {} 
+ 
+  void print(raw_ostream &O, const Module* = nullptr) const override; 
+ 
+protected: 
+  void scheduleRegions(ScheduleDAGInstrs &Scheduler, bool FixKillFlags); 
+}; 
+ 
+/// MachineScheduler runs after coalescing and before register allocation. 
+class MachineScheduler : public MachineSchedulerBase { 
+public: 
+  MachineScheduler(); 
+ 
+  void getAnalysisUsage(AnalysisUsage &AU) const override; 
+ 
+  bool runOnMachineFunction(MachineFunction&) override; 
+ 
+  static char ID; // Class identification, replacement for typeinfo 
+ 
+protected: 
+  ScheduleDAGInstrs *createMachineScheduler(); 
+}; 
+ 
+/// PostMachineScheduler runs after shortly before code emission. 
+class PostMachineScheduler : public MachineSchedulerBase { 
+public: 
+  PostMachineScheduler(); 
+ 
+  void getAnalysisUsage(AnalysisUsage &AU) const override; 
+ 
+  bool runOnMachineFunction(MachineFunction&) override; 
+ 
+  static char ID; // Class identification, replacement for typeinfo 
+ 
+protected: 
+  ScheduleDAGInstrs *createPostMachineScheduler(); 
+}; 
+ 
+} // end anonymous namespace 
+ 
+char MachineScheduler::ID = 0; 
+ 
+char &llvm::MachineSchedulerID = MachineScheduler::ID; 
+ 
+INITIALIZE_PASS_BEGIN(MachineScheduler, DEBUG_TYPE, 
+                      "Machine Instruction Scheduler", false, false) 
+INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass) 
+INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree) 
+INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo) 
+INITIALIZE_PASS_DEPENDENCY(SlotIndexes) 
+INITIALIZE_PASS_DEPENDENCY(LiveIntervals) 
+INITIALIZE_PASS_END(MachineScheduler, DEBUG_TYPE, 
+                    "Machine Instruction Scheduler", false, false) 
+ 
+MachineScheduler::MachineScheduler() : MachineSchedulerBase(ID) { 
+  initializeMachineSchedulerPass(*PassRegistry::getPassRegistry()); 
+} 
+ 
+void MachineScheduler::getAnalysisUsage(AnalysisUsage &AU) const { 
+  AU.setPreservesCFG(); 
+  AU.addRequired<MachineDominatorTree>(); 
+  AU.addRequired<MachineLoopInfo>(); 
+  AU.addRequired<AAResultsWrapperPass>(); 
+  AU.addRequired<TargetPassConfig>(); 
+  AU.addRequired<SlotIndexes>(); 
+  AU.addPreserved<SlotIndexes>(); 
+  AU.addRequired<LiveIntervals>(); 
+  AU.addPreserved<LiveIntervals>(); 
+  MachineFunctionPass::getAnalysisUsage(AU); 
+} 
+ 
+char PostMachineScheduler::ID = 0; 
+ 
+char &llvm::PostMachineSchedulerID = PostMachineScheduler::ID; 
+ 
 INITIALIZE_PASS_BEGIN(PostMachineScheduler, "postmisched",
                       "PostRA Machine Instruction Scheduler", false, false)
 INITIALIZE_PASS_DEPENDENCY(MachineDominatorTree)
@@ -247,1360 +247,1360 @@ INITIALIZE_PASS_DEPENDENCY(MachineLoopInfo)
 INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
 INITIALIZE_PASS_END(PostMachineScheduler, "postmisched",
                     "PostRA Machine Instruction Scheduler", false, false)
-
-PostMachineScheduler::PostMachineScheduler() : MachineSchedulerBase(ID) {
-  initializePostMachineSchedulerPass(*PassRegistry::getPassRegistry());
-}
-
-void PostMachineScheduler::getAnalysisUsage(AnalysisUsage &AU) const {
-  AU.setPreservesCFG();
-  AU.addRequired<MachineDominatorTree>();
-  AU.addRequired<MachineLoopInfo>();
-  AU.addRequired<AAResultsWrapperPass>();
-  AU.addRequired<TargetPassConfig>();
-  MachineFunctionPass::getAnalysisUsage(AU);
-}
-
-MachinePassRegistry<MachineSchedRegistry::ScheduleDAGCtor>
-    MachineSchedRegistry::Registry;
-
-/// A dummy default scheduler factory indicates whether the scheduler
-/// is overridden on the command line.
-static ScheduleDAGInstrs *useDefaultMachineSched(MachineSchedContext *C) {
-  return nullptr;
-}
-
-/// MachineSchedOpt allows command line selection of the scheduler.
-static cl::opt<MachineSchedRegistry::ScheduleDAGCtor, false,
-               RegisterPassParser<MachineSchedRegistry>>
-MachineSchedOpt("misched",
-                cl::init(&useDefaultMachineSched), cl::Hidden,
-                cl::desc("Machine instruction scheduler to use"));
-
-static MachineSchedRegistry
-DefaultSchedRegistry("default", "Use the target's default scheduler choice.",
-                     useDefaultMachineSched);
-
-static cl::opt<bool> EnableMachineSched(
-    "enable-misched",
-    cl::desc("Enable the machine instruction scheduling pass."), cl::init(true),
-    cl::Hidden);
-
-static cl::opt<bool> EnablePostRAMachineSched(
-    "enable-post-misched",
-    cl::desc("Enable the post-ra machine instruction scheduling pass."),
-    cl::init(true), cl::Hidden);
-
-/// Decrement this iterator until reaching the top or a non-debug instr.
-static MachineBasicBlock::const_iterator
-priorNonDebug(MachineBasicBlock::const_iterator I,
-              MachineBasicBlock::const_iterator Beg) {
-  assert(I != Beg && "reached the top of the region, cannot decrement");
-  while (--I != Beg) {
-    if (!I->isDebugInstr())
-      break;
-  }
-  return I;
-}
-
-/// Non-const version.
-static MachineBasicBlock::iterator
-priorNonDebug(MachineBasicBlock::iterator I,
-              MachineBasicBlock::const_iterator Beg) {
-  return priorNonDebug(MachineBasicBlock::const_iterator(I), Beg)
-      .getNonConstIterator();
-}
-
-/// If this iterator is a debug value, increment until reaching the End or a
-/// non-debug instruction.
-static MachineBasicBlock::const_iterator
-nextIfDebug(MachineBasicBlock::const_iterator I,
-            MachineBasicBlock::const_iterator End) {
-  for(; I != End; ++I) {
-    if (!I->isDebugInstr())
-      break;
-  }
-  return I;
-}
-
-/// Non-const version.
-static MachineBasicBlock::iterator
-nextIfDebug(MachineBasicBlock::iterator I,
-            MachineBasicBlock::const_iterator End) {
-  return nextIfDebug(MachineBasicBlock::const_iterator(I), End)
-      .getNonConstIterator();
-}
-
-/// Instantiate a ScheduleDAGInstrs that will be owned by the caller.
-ScheduleDAGInstrs *MachineScheduler::createMachineScheduler() {
-  // Select the scheduler, or set the default.
-  MachineSchedRegistry::ScheduleDAGCtor Ctor = MachineSchedOpt;
-  if (Ctor != useDefaultMachineSched)
-    return Ctor(this);
-
-  // Get the default scheduler set by the target for this function.
-  ScheduleDAGInstrs *Scheduler = PassConfig->createMachineScheduler(this);
-  if (Scheduler)
-    return Scheduler;
-
-  // Default to GenericScheduler.
-  return createGenericSchedLive(this);
-}
-
-/// Instantiate a ScheduleDAGInstrs for PostRA scheduling that will be owned by
-/// the caller. We don't have a command line option to override the postRA
-/// scheduler. The Target must configure it.
-ScheduleDAGInstrs *PostMachineScheduler::createPostMachineScheduler() {
-  // Get the postRA scheduler set by the target for this function.
-  ScheduleDAGInstrs *Scheduler = PassConfig->createPostMachineScheduler(this);
-  if (Scheduler)
-    return Scheduler;
-
-  // Default to GenericScheduler.
-  return createGenericSchedPostRA(this);
-}
-
-/// Top-level MachineScheduler pass driver.
-///
-/// Visit blocks in function order. Divide each block into scheduling regions
-/// and visit them bottom-up. Visiting regions bottom-up is not required, but is
-/// consistent with the DAG builder, which traverses the interior of the
-/// scheduling regions bottom-up.
-///
-/// This design avoids exposing scheduling boundaries to the DAG builder,
-/// simplifying the DAG builder's support for "special" target instructions.
-/// At the same time the design allows target schedulers to operate across
-/// scheduling boundaries, for example to bundle the boundary instructions
-/// without reordering them. This creates complexity, because the target
-/// scheduler must update the RegionBegin and RegionEnd positions cached by
-/// ScheduleDAGInstrs whenever adding or removing instructions. A much simpler
-/// design would be to split blocks at scheduling boundaries, but LLVM has a
-/// general bias against block splitting purely for implementation simplicity.
-bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) {
-  if (skipFunction(mf.getFunction()))
-    return false;
-
-  if (EnableMachineSched.getNumOccurrences()) {
-    if (!EnableMachineSched)
-      return false;
-  } else if (!mf.getSubtarget().enableMachineScheduler())
-    return false;
-
-  LLVM_DEBUG(dbgs() << "Before MISched:\n"; mf.print(dbgs()));
-
-  // Initialize the context of the pass.
-  MF = &mf;
-  MLI = &getAnalysis<MachineLoopInfo>();
-  MDT = &getAnalysis<MachineDominatorTree>();
-  PassConfig = &getAnalysis<TargetPassConfig>();
-  AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
-
-  LIS = &getAnalysis<LiveIntervals>();
-
-  if (VerifyScheduling) {
-    LLVM_DEBUG(LIS->dump());
-    MF->verify(this, "Before machine scheduling.");
-  }
-  RegClassInfo->runOnMachineFunction(*MF);
-
-  // Instantiate the selected scheduler for this target, function, and
-  // optimization level.
-  std::unique_ptr<ScheduleDAGInstrs> Scheduler(createMachineScheduler());
-  scheduleRegions(*Scheduler, false);
-
-  LLVM_DEBUG(LIS->dump());
-  if (VerifyScheduling)
-    MF->verify(this, "After machine scheduling.");
-  return true;
-}
-
-bool PostMachineScheduler::runOnMachineFunction(MachineFunction &mf) {
-  if (skipFunction(mf.getFunction()))
-    return false;
-
-  if (EnablePostRAMachineSched.getNumOccurrences()) {
-    if (!EnablePostRAMachineSched)
-      return false;
-  } else if (!mf.getSubtarget().enablePostRAMachineScheduler()) {
-    LLVM_DEBUG(dbgs() << "Subtarget disables post-MI-sched.\n");
-    return false;
-  }
-  LLVM_DEBUG(dbgs() << "Before post-MI-sched:\n"; mf.print(dbgs()));
-
-  // Initialize the context of the pass.
-  MF = &mf;
-  MLI = &getAnalysis<MachineLoopInfo>();
-  PassConfig = &getAnalysis<TargetPassConfig>();
-  AA = &getAnalysis<AAResultsWrapperPass>().getAAResults();
-
-  if (VerifyScheduling)
-    MF->verify(this, "Before post machine scheduling.");
-
-  // Instantiate the selected scheduler for this target, function, and
-  // optimization level.
-  std::unique_ptr<ScheduleDAGInstrs> Scheduler(createPostMachineScheduler());
-  scheduleRegions(*Scheduler, true);
-
-  if (VerifyScheduling)
-    MF->verify(this, "After post machine scheduling.");
-  return true;
-}
-
-/// Return true of the given instruction should not be included in a scheduling
-/// region.
-///
-/// MachineScheduler does not currently support scheduling across calls. To
-/// handle calls, the DAG builder needs to be modified to create register
-/// anti/output dependencies on the registers clobbered by the call's regmask
-/// operand. In PreRA scheduling, the stack pointer adjustment already prevents
-/// scheduling across calls. In PostRA scheduling, we need the isCall to enforce
-/// the boundary, but there would be no benefit to postRA scheduling across
-/// calls this late anyway.
-static bool isSchedBoundary(MachineBasicBlock::iterator MI,
-                            MachineBasicBlock *MBB,
-                            MachineFunction *MF,
-                            const TargetInstrInfo *TII) {
-  return MI->isCall() || TII->isSchedulingBoundary(*MI, MBB, *MF);
-}
-
-/// A region of an MBB for scheduling.
-namespace {
-struct SchedRegion {
-  /// RegionBegin is the first instruction in the scheduling region, and
-  /// RegionEnd is either MBB->end() or the scheduling boundary after the
-  /// last instruction in the scheduling region. These iterators cannot refer
-  /// to instructions outside of the identified scheduling region because
-  /// those may be reordered before scheduling this region.
-  MachineBasicBlock::iterator RegionBegin;
-  MachineBasicBlock::iterator RegionEnd;
-  unsigned NumRegionInstrs;
-
-  SchedRegion(MachineBasicBlock::iterator B, MachineBasicBlock::iterator E,
-              unsigned N) :
-    RegionBegin(B), RegionEnd(E), NumRegionInstrs(N) {}
-};
-} // end anonymous namespace
-
-using MBBRegionsVector = SmallVector<SchedRegion, 16>;
-
-static void
-getSchedRegions(MachineBasicBlock *MBB,
-                MBBRegionsVector &Regions,
-                bool RegionsTopDown) {
-  MachineFunction *MF = MBB->getParent();
-  const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
-
-  MachineBasicBlock::iterator I = nullptr;
-  for(MachineBasicBlock::iterator RegionEnd = MBB->end();
-      RegionEnd != MBB->begin(); RegionEnd = I) {
-
-    // Avoid decrementing RegionEnd for blocks with no terminator.
-    if (RegionEnd != MBB->end() ||
-        isSchedBoundary(&*std::prev(RegionEnd), &*MBB, MF, TII)) {
-      --RegionEnd;
-    }
-
-    // The next region starts above the previous region. Look backward in the
-    // instruction stream until we find the nearest boundary.
-    unsigned NumRegionInstrs = 0;
-    I = RegionEnd;
-    for (;I != MBB->begin(); --I) {
-      MachineInstr &MI = *std::prev(I);
-      if (isSchedBoundary(&MI, &*MBB, MF, TII))
-        break;
-      if (!MI.isDebugInstr()) {
-        // MBB::size() uses instr_iterator to count. Here we need a bundle to
-        // count as a single instruction.
-        ++NumRegionInstrs;
-      }
-    }
-
-    // It's possible we found a scheduling region that only has debug
-    // instructions. Don't bother scheduling these.
-    if (NumRegionInstrs != 0)
-      Regions.push_back(SchedRegion(I, RegionEnd, NumRegionInstrs));
-  }
-
-  if (RegionsTopDown)
-    std::reverse(Regions.begin(), Regions.end());
-}
-
-/// Main driver for both MachineScheduler and PostMachineScheduler.
-void MachineSchedulerBase::scheduleRegions(ScheduleDAGInstrs &Scheduler,
-                                           bool FixKillFlags) {
-  // Visit all machine basic blocks.
-  //
-  // TODO: Visit blocks in global postorder or postorder within the bottom-up
-  // loop tree. Then we can optionally compute global RegPressure.
-  for (MachineFunction::iterator MBB = MF->begin(), MBBEnd = MF->end();
-       MBB != MBBEnd; ++MBB) {
-
-    Scheduler.startBlock(&*MBB);
-
-#ifndef NDEBUG
-    if (SchedOnlyFunc.getNumOccurrences() && SchedOnlyFunc != MF->getName())
-      continue;
-    if (SchedOnlyBlock.getNumOccurrences()
-        && (int)SchedOnlyBlock != MBB->getNumber())
-      continue;
-#endif
-
-    // Break the block into scheduling regions [I, RegionEnd). RegionEnd
-    // points to the scheduling boundary at the bottom of the region. The DAG
-    // does not include RegionEnd, but the region does (i.e. the next
-    // RegionEnd is above the previous RegionBegin). If the current block has
-    // no terminator then RegionEnd == MBB->end() for the bottom region.
-    //
-    // All the regions of MBB are first found and stored in MBBRegions, which
-    // will be processed (MBB) top-down if initialized with true.
-    //
-    // The Scheduler may insert instructions during either schedule() or
-    // exitRegion(), even for empty regions. So the local iterators 'I' and
-    // 'RegionEnd' are invalid across these calls. Instructions must not be
-    // added to other regions than the current one without updating MBBRegions.
-
-    MBBRegionsVector MBBRegions;
-    getSchedRegions(&*MBB, MBBRegions, Scheduler.doMBBSchedRegionsTopDown());
-    for (MBBRegionsVector::iterator R = MBBRegions.begin();
-         R != MBBRegions.end(); ++R) {
-      MachineBasicBlock::iterator I = R->RegionBegin;
-      MachineBasicBlock::iterator RegionEnd = R->RegionEnd;
-      unsigned NumRegionInstrs = R->NumRegionInstrs;
-
-      // Notify the scheduler of the region, even if we may skip scheduling
-      // it. Perhaps it still needs to be bundled.
-      Scheduler.enterRegion(&*MBB, I, RegionEnd, NumRegionInstrs);
-
-      // Skip empty scheduling regions (0 or 1 schedulable instructions).
-      if (I == RegionEnd || I == std::prev(RegionEnd)) {
-        // Close the current region. Bundle the terminator if needed.
-        // This invalidates 'RegionEnd' and 'I'.
-        Scheduler.exitRegion();
-        continue;
-      }
-      LLVM_DEBUG(dbgs() << "********** MI Scheduling **********\n");
-      LLVM_DEBUG(dbgs() << MF->getName() << ":" << printMBBReference(*MBB)
-                        << " " << MBB->getName() << "\n  From: " << *I
-                        << "    To: ";
-                 if (RegionEnd != MBB->end()) dbgs() << *RegionEnd;
-                 else dbgs() << "End";
-                 dbgs() << " RegionInstrs: " << NumRegionInstrs << '\n');
-      if (DumpCriticalPathLength) {
-        errs() << MF->getName();
-        errs() << ":%bb. " << MBB->getNumber();
-        errs() << " " << MBB->getName() << " \n";
-      }
-
-      // Schedule a region: possibly reorder instructions.
-      // This invalidates the original region iterators.
-      Scheduler.schedule();
-
-      // Close the current region.
-      Scheduler.exitRegion();
-    }
-    Scheduler.finishBlock();
-    // FIXME: Ideally, no further passes should rely on kill flags. However,
-    // thumb2 size reduction is currently an exception, so the PostMIScheduler
-    // needs to do this.
-    if (FixKillFlags)
-      Scheduler.fixupKills(*MBB);
-  }
-  Scheduler.finalizeSchedule();
-}
-
-void MachineSchedulerBase::print(raw_ostream &O, const Module* m) const {
-  // unimplemented
-}
-
-#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-LLVM_DUMP_METHOD void ReadyQueue::dump() const {
-  dbgs() << "Queue " << Name << ": ";
-  for (const SUnit *SU : Queue)
-    dbgs() << SU->NodeNum << " ";
-  dbgs() << "\n";
-}
-#endif
-
-//===----------------------------------------------------------------------===//
-// ScheduleDAGMI - Basic machine instruction scheduling. This is
-// independent of PreRA/PostRA scheduling and involves no extra book-keeping for
-// virtual registers.
-// ===----------------------------------------------------------------------===/
-
-// Provide a vtable anchor.
-ScheduleDAGMI::~ScheduleDAGMI() = default;
-
-/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. When
-/// NumPredsLeft reaches zero, release the successor node.
-///
-/// FIXME: Adjust SuccSU height based on MinLatency.
-void ScheduleDAGMI::releaseSucc(SUnit *SU, SDep *SuccEdge) {
-  SUnit *SuccSU = SuccEdge->getSUnit();
-
-  if (SuccEdge->isWeak()) {
-    --SuccSU->WeakPredsLeft;
-    if (SuccEdge->isCluster())
-      NextClusterSucc = SuccSU;
-    return;
-  }
-#ifndef NDEBUG
-  if (SuccSU->NumPredsLeft == 0) {
-    dbgs() << "*** Scheduling failed! ***\n";
-    dumpNode(*SuccSU);
-    dbgs() << " has been released too many times!\n";
-    llvm_unreachable(nullptr);
-  }
-#endif
-  // SU->TopReadyCycle was set to CurrCycle when it was scheduled. However,
-  // CurrCycle may have advanced since then.
-  if (SuccSU->TopReadyCycle < SU->TopReadyCycle + SuccEdge->getLatency())
-    SuccSU->TopReadyCycle = SU->TopReadyCycle + SuccEdge->getLatency();
-
-  --SuccSU->NumPredsLeft;
-  if (SuccSU->NumPredsLeft == 0 && SuccSU != &ExitSU)
-    SchedImpl->releaseTopNode(SuccSU);
-}
-
-/// releaseSuccessors - Call releaseSucc on each of SU's successors.
-void ScheduleDAGMI::releaseSuccessors(SUnit *SU) {
-  for (SDep &Succ : SU->Succs)
-    releaseSucc(SU, &Succ);
-}
-
-/// ReleasePred - Decrement the NumSuccsLeft count of a predecessor. When
-/// NumSuccsLeft reaches zero, release the predecessor node.
-///
-/// FIXME: Adjust PredSU height based on MinLatency.
-void ScheduleDAGMI::releasePred(SUnit *SU, SDep *PredEdge) {
-  SUnit *PredSU = PredEdge->getSUnit();
-
-  if (PredEdge->isWeak()) {
-    --PredSU->WeakSuccsLeft;
-    if (PredEdge->isCluster())
-      NextClusterPred = PredSU;
-    return;
-  }
-#ifndef NDEBUG
-  if (PredSU->NumSuccsLeft == 0) {
-    dbgs() << "*** Scheduling failed! ***\n";
-    dumpNode(*PredSU);
-    dbgs() << " has been released too many times!\n";
-    llvm_unreachable(nullptr);
-  }
-#endif
-  // SU->BotReadyCycle was set to CurrCycle when it was scheduled. However,
-  // CurrCycle may have advanced since then.
-  if (PredSU->BotReadyCycle < SU->BotReadyCycle + PredEdge->getLatency())
-    PredSU->BotReadyCycle = SU->BotReadyCycle + PredEdge->getLatency();
-
-  --PredSU->NumSuccsLeft;
-  if (PredSU->NumSuccsLeft == 0 && PredSU != &EntrySU)
-    SchedImpl->releaseBottomNode(PredSU);
-}
-
-/// releasePredecessors - Call releasePred on each of SU's predecessors.
-void ScheduleDAGMI::releasePredecessors(SUnit *SU) {
-  for (SDep &Pred : SU->Preds)
-    releasePred(SU, &Pred);
-}
-
-void ScheduleDAGMI::startBlock(MachineBasicBlock *bb) {
-  ScheduleDAGInstrs::startBlock(bb);
-  SchedImpl->enterMBB(bb);
-}
-
-void ScheduleDAGMI::finishBlock() {
-  SchedImpl->leaveMBB();
-  ScheduleDAGInstrs::finishBlock();
-}
-
-/// enterRegion - Called back from MachineScheduler::runOnMachineFunction after
-/// crossing a scheduling boundary. [begin, end) includes all instructions in
-/// the region, including the boundary itself and single-instruction regions
-/// that don't get scheduled.
-void ScheduleDAGMI::enterRegion(MachineBasicBlock *bb,
-                                     MachineBasicBlock::iterator begin,
-                                     MachineBasicBlock::iterator end,
-                                     unsigned regioninstrs)
-{
-  ScheduleDAGInstrs::enterRegion(bb, begin, end, regioninstrs);
-
-  SchedImpl->initPolicy(begin, end, regioninstrs);
-}
-
-/// This is normally called from the main scheduler loop but may also be invoked
-/// by the scheduling strategy to perform additional code motion.
-void ScheduleDAGMI::moveInstruction(
-  MachineInstr *MI, MachineBasicBlock::iterator InsertPos) {
-  // Advance RegionBegin if the first instruction moves down.
-  if (&*RegionBegin == MI)
-    ++RegionBegin;
-
-  // Update the instruction stream.
-  BB->splice(InsertPos, BB, MI);
-
-  // Update LiveIntervals
-  if (LIS)
-    LIS->handleMove(*MI, /*UpdateFlags=*/true);
-
-  // Recede RegionBegin if an instruction moves above the first.
-  if (RegionBegin == InsertPos)
-    RegionBegin = MI;
-}
-
-bool ScheduleDAGMI::checkSchedLimit() {
-#ifndef NDEBUG
-  if (NumInstrsScheduled == MISchedCutoff && MISchedCutoff != ~0U) {
-    CurrentTop = CurrentBottom;
-    return false;
-  }
-  ++NumInstrsScheduled;
-#endif
-  return true;
-}
-
-/// Per-region scheduling driver, called back from
-/// MachineScheduler::runOnMachineFunction. This is a simplified driver that
-/// does not consider liveness or register pressure. It is useful for PostRA
-/// scheduling and potentially other custom schedulers.
-void ScheduleDAGMI::schedule() {
-  LLVM_DEBUG(dbgs() << "ScheduleDAGMI::schedule starting\n");
-  LLVM_DEBUG(SchedImpl->dumpPolicy());
-
-  // Build the DAG.
-  buildSchedGraph(AA);
-
-  postprocessDAG();
-
-  SmallVector<SUnit*, 8> TopRoots, BotRoots;
-  findRootsAndBiasEdges(TopRoots, BotRoots);
-
-  LLVM_DEBUG(dump());
-  if (PrintDAGs) dump();
-  if (ViewMISchedDAGs) viewGraph();
-
-  // Initialize the strategy before modifying the DAG.
-  // This may initialize a DFSResult to be used for queue priority.
-  SchedImpl->initialize(this);
-
-  // Initialize ready queues now that the DAG and priority data are finalized.
-  initQueues(TopRoots, BotRoots);
-
-  bool IsTopNode = false;
-  while (true) {
-    LLVM_DEBUG(dbgs() << "** ScheduleDAGMI::schedule picking next node\n");
-    SUnit *SU = SchedImpl->pickNode(IsTopNode);
-    if (!SU) break;
-
-    assert(!SU->isScheduled && "Node already scheduled");
-    if (!checkSchedLimit())
-      break;
-
-    MachineInstr *MI = SU->getInstr();
-    if (IsTopNode) {
-      assert(SU->isTopReady() && "node still has unscheduled dependencies");
-      if (&*CurrentTop == MI)
-        CurrentTop = nextIfDebug(++CurrentTop, CurrentBottom);
-      else
-        moveInstruction(MI, CurrentTop);
-    } else {
-      assert(SU->isBottomReady() && "node still has unscheduled dependencies");
-      MachineBasicBlock::iterator priorII =
-        priorNonDebug(CurrentBottom, CurrentTop);
-      if (&*priorII == MI)
-        CurrentBottom = priorII;
-      else {
-        if (&*CurrentTop == MI)
-          CurrentTop = nextIfDebug(++CurrentTop, priorII);
-        moveInstruction(MI, CurrentBottom);
-        CurrentBottom = MI;
-      }
-    }
-    // Notify the scheduling strategy before updating the DAG.
-    // This sets the scheduled node's ReadyCycle to CurrCycle. When updateQueues
-    // runs, it can then use the accurate ReadyCycle time to determine whether
-    // newly released nodes can move to the readyQ.
-    SchedImpl->schedNode(SU, IsTopNode);
-
-    updateQueues(SU, IsTopNode);
-  }
-  assert(CurrentTop == CurrentBottom && "Nonempty unscheduled zone.");
-
-  placeDebugValues();
-
-  LLVM_DEBUG({
-    dbgs() << "*** Final schedule for "
-           << printMBBReference(*begin()->getParent()) << " ***\n";
-    dumpSchedule();
-    dbgs() << '\n';
-  });
-}
-
-/// Apply each ScheduleDAGMutation step in order.
-void ScheduleDAGMI::postprocessDAG() {
-  for (auto &m : Mutations)
-    m->apply(this);
-}
-
-void ScheduleDAGMI::
-findRootsAndBiasEdges(SmallVectorImpl<SUnit*> &TopRoots,
-                      SmallVectorImpl<SUnit*> &BotRoots) {
-  for (SUnit &SU : SUnits) {
-    assert(!SU.isBoundaryNode() && "Boundary node should not be in SUnits");
-
-    // Order predecessors so DFSResult follows the critical path.
-    SU.biasCriticalPath();
-
-    // A SUnit is ready to top schedule if it has no predecessors.
-    if (!SU.NumPredsLeft)
-      TopRoots.push_back(&SU);
-    // A SUnit is ready to bottom schedule if it has no successors.
-    if (!SU.NumSuccsLeft)
-      BotRoots.push_back(&SU);
-  }
-  ExitSU.biasCriticalPath();
-}
-
-/// Identify DAG roots and setup scheduler queues.
-void ScheduleDAGMI::initQueues(ArrayRef<SUnit*> TopRoots,
-                               ArrayRef<SUnit*> BotRoots) {
-  NextClusterSucc = nullptr;
-  NextClusterPred = nullptr;
-
-  // Release all DAG roots for scheduling, not including EntrySU/ExitSU.
-  //
-  // Nodes with unreleased weak edges can still be roots.
-  // Release top roots in forward order.
-  for (SUnit *SU : TopRoots)
-    SchedImpl->releaseTopNode(SU);
-
-  // Release bottom roots in reverse order so the higher priority nodes appear
-  // first. This is more natural and slightly more efficient.
-  for (SmallVectorImpl<SUnit*>::const_reverse_iterator
-         I = BotRoots.rbegin(), E = BotRoots.rend(); I != E; ++I) {
-    SchedImpl->releaseBottomNode(*I);
-  }
-
-  releaseSuccessors(&EntrySU);
-  releasePredecessors(&ExitSU);
-
-  SchedImpl->registerRoots();
-
-  // Advance past initial DebugValues.
-  CurrentTop = nextIfDebug(RegionBegin, RegionEnd);
-  CurrentBottom = RegionEnd;
-}
-
-/// Update scheduler queues after scheduling an instruction.
-void ScheduleDAGMI::updateQueues(SUnit *SU, bool IsTopNode) {
-  // Release dependent instructions for scheduling.
-  if (IsTopNode)
-    releaseSuccessors(SU);
-  else
-    releasePredecessors(SU);
-
-  SU->isScheduled = true;
-}
-
-/// Reinsert any remaining debug_values, just like the PostRA scheduler.
-void ScheduleDAGMI::placeDebugValues() {
-  // If first instruction was a DBG_VALUE then put it back.
-  if (FirstDbgValue) {
-    BB->splice(RegionBegin, BB, FirstDbgValue);
-    RegionBegin = FirstDbgValue;
-  }
-
-  for (std::vector<std::pair<MachineInstr *, MachineInstr *>>::iterator
-         DI = DbgValues.end(), DE = DbgValues.begin(); DI != DE; --DI) {
-    std::pair<MachineInstr *, MachineInstr *> P = *std::prev(DI);
-    MachineInstr *DbgValue = P.first;
-    MachineBasicBlock::iterator OrigPrevMI = P.second;
-    if (&*RegionBegin == DbgValue)
-      ++RegionBegin;
-    BB->splice(++OrigPrevMI, BB, DbgValue);
-    if (OrigPrevMI == std::prev(RegionEnd))
-      RegionEnd = DbgValue;
-  }
-  DbgValues.clear();
-  FirstDbgValue = nullptr;
-}
-
-#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-LLVM_DUMP_METHOD void ScheduleDAGMI::dumpSchedule() const {
-  for (MachineBasicBlock::iterator MI = begin(), ME = end(); MI != ME; ++MI) {
-    if (SUnit *SU = getSUnit(&(*MI)))
-      dumpNode(*SU);
-    else
-      dbgs() << "Missing SUnit\n";
-  }
-}
-#endif
-
-//===----------------------------------------------------------------------===//
-// ScheduleDAGMILive - Base class for MachineInstr scheduling with LiveIntervals
-// preservation.
-//===----------------------------------------------------------------------===//
-
-ScheduleDAGMILive::~ScheduleDAGMILive() {
-  delete DFSResult;
-}
-
-void ScheduleDAGMILive::collectVRegUses(SUnit &SU) {
-  const MachineInstr &MI = *SU.getInstr();
-  for (const MachineOperand &MO : MI.operands()) {
-    if (!MO.isReg())
-      continue;
-    if (!MO.readsReg())
-      continue;
-    if (TrackLaneMasks && !MO.isUse())
-      continue;
-
-    Register Reg = MO.getReg();
-    if (!Register::isVirtualRegister(Reg))
-      continue;
-
-    // Ignore re-defs.
-    if (TrackLaneMasks) {
-      bool FoundDef = false;
-      for (const MachineOperand &MO2 : MI.operands()) {
-        if (MO2.isReg() && MO2.isDef() && MO2.getReg() == Reg && !MO2.isDead()) {
-          FoundDef = true;
-          break;
-        }
-      }
-      if (FoundDef)
-        continue;
-    }
-
-    // Record this local VReg use.
-    VReg2SUnitMultiMap::iterator UI = VRegUses.find(Reg);
-    for (; UI != VRegUses.end(); ++UI) {
-      if (UI->SU == &SU)
-        break;
-    }
-    if (UI == VRegUses.end())
-      VRegUses.insert(VReg2SUnit(Reg, LaneBitmask::getNone(), &SU));
-  }
-}
-
-/// enterRegion - Called back from MachineScheduler::runOnMachineFunction after
-/// crossing a scheduling boundary. [begin, end) includes all instructions in
-/// the region, including the boundary itself and single-instruction regions
-/// that don't get scheduled.
-void ScheduleDAGMILive::enterRegion(MachineBasicBlock *bb,
-                                MachineBasicBlock::iterator begin,
-                                MachineBasicBlock::iterator end,
-                                unsigned regioninstrs)
-{
-  // ScheduleDAGMI initializes SchedImpl's per-region policy.
-  ScheduleDAGMI::enterRegion(bb, begin, end, regioninstrs);
-
-  // For convenience remember the end of the liveness region.
-  LiveRegionEnd = (RegionEnd == bb->end()) ? RegionEnd : std::next(RegionEnd);
-
-  SUPressureDiffs.clear();
-
-  ShouldTrackPressure = SchedImpl->shouldTrackPressure();
-  ShouldTrackLaneMasks = SchedImpl->shouldTrackLaneMasks();
-
-  assert((!ShouldTrackLaneMasks || ShouldTrackPressure) &&
-         "ShouldTrackLaneMasks requires ShouldTrackPressure");
-}
-
-// Setup the register pressure trackers for the top scheduled and bottom
-// scheduled regions.
-void ScheduleDAGMILive::initRegPressure() {
-  VRegUses.clear();
-  VRegUses.setUniverse(MRI.getNumVirtRegs());
-  for (SUnit &SU : SUnits)
-    collectVRegUses(SU);
-
-  TopRPTracker.init(&MF, RegClassInfo, LIS, BB, RegionBegin,
-                    ShouldTrackLaneMasks, false);
-  BotRPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd,
-                    ShouldTrackLaneMasks, false);
-
-  // Close the RPTracker to finalize live ins.
-  RPTracker.closeRegion();
-
-  LLVM_DEBUG(RPTracker.dump());
-
-  // Initialize the live ins and live outs.
-  TopRPTracker.addLiveRegs(RPTracker.getPressure().LiveInRegs);
-  BotRPTracker.addLiveRegs(RPTracker.getPressure().LiveOutRegs);
-
-  // Close one end of the tracker so we can call
-  // getMaxUpward/DownwardPressureDelta before advancing across any
-  // instructions. This converts currently live regs into live ins/outs.
-  TopRPTracker.closeTop();
-  BotRPTracker.closeBottom();
-
-  BotRPTracker.initLiveThru(RPTracker);
-  if (!BotRPTracker.getLiveThru().empty()) {
-    TopRPTracker.initLiveThru(BotRPTracker.getLiveThru());
-    LLVM_DEBUG(dbgs() << "Live Thru: ";
-               dumpRegSetPressure(BotRPTracker.getLiveThru(), TRI));
-  };
-
-  // For each live out vreg reduce the pressure change associated with other
-  // uses of the same vreg below the live-out reaching def.
-  updatePressureDiffs(RPTracker.getPressure().LiveOutRegs);
-
-  // Account for liveness generated by the region boundary.
-  if (LiveRegionEnd != RegionEnd) {
-    SmallVector<RegisterMaskPair, 8> LiveUses;
-    BotRPTracker.recede(&LiveUses);
-    updatePressureDiffs(LiveUses);
-  }
-
-  LLVM_DEBUG(dbgs() << "Top Pressure:\n";
-             dumpRegSetPressure(TopRPTracker.getRegSetPressureAtPos(), TRI);
-             dbgs() << "Bottom Pressure:\n";
-             dumpRegSetPressure(BotRPTracker.getRegSetPressureAtPos(), TRI););
-
-  assert((BotRPTracker.getPos() == RegionEnd ||
-          (RegionEnd->isDebugInstr() &&
-           BotRPTracker.getPos() == priorNonDebug(RegionEnd, RegionBegin))) &&
-         "Can't find the region bottom");
-
-  // Cache the list of excess pressure sets in this region. This will also track
-  // the max pressure in the scheduled code for these sets.
-  RegionCriticalPSets.clear();
-  const std::vector<unsigned> &RegionPressure =
-    RPTracker.getPressure().MaxSetPressure;
-  for (unsigned i = 0, e = RegionPressure.size(); i < e; ++i) {
-    unsigned Limit = RegClassInfo->getRegPressureSetLimit(i);
-    if (RegionPressure[i] > Limit) {
-      LLVM_DEBUG(dbgs() << TRI->getRegPressureSetName(i) << " Limit " << Limit
-                        << " Actual " << RegionPressure[i] << "\n");
-      RegionCriticalPSets.push_back(PressureChange(i));
-    }
-  }
-  LLVM_DEBUG(dbgs() << "Excess PSets: ";
-             for (const PressureChange &RCPS
-                  : RegionCriticalPSets) dbgs()
-             << TRI->getRegPressureSetName(RCPS.getPSet()) << " ";
-             dbgs() << "\n");
-}
-
-void ScheduleDAGMILive::
-updateScheduledPressure(const SUnit *SU,
-                        const std::vector<unsigned> &NewMaxPressure) {
-  const PressureDiff &PDiff = getPressureDiff(SU);
-  unsigned CritIdx = 0, CritEnd = RegionCriticalPSets.size();
-  for (const PressureChange &PC : PDiff) {
-    if (!PC.isValid())
-      break;
-    unsigned ID = PC.getPSet();
-    while (CritIdx != CritEnd && RegionCriticalPSets[CritIdx].getPSet() < ID)
-      ++CritIdx;
-    if (CritIdx != CritEnd && RegionCriticalPSets[CritIdx].getPSet() == ID) {
-      if ((int)NewMaxPressure[ID] > RegionCriticalPSets[CritIdx].getUnitInc()
-          && NewMaxPressure[ID] <= (unsigned)std::numeric_limits<int16_t>::max())
-        RegionCriticalPSets[CritIdx].setUnitInc(NewMaxPressure[ID]);
-    }
-    unsigned Limit = RegClassInfo->getRegPressureSetLimit(ID);
-    if (NewMaxPressure[ID] >= Limit - 2) {
-      LLVM_DEBUG(dbgs() << "  " << TRI->getRegPressureSetName(ID) << ": "
-                        << NewMaxPressure[ID]
-                        << ((NewMaxPressure[ID] > Limit) ? " > " : " <= ")
-                        << Limit << "(+ " << BotRPTracker.getLiveThru()[ID]
-                        << " livethru)\n");
-    }
-  }
-}
-
-/// Update the PressureDiff array for liveness after scheduling this
-/// instruction.
-void ScheduleDAGMILive::updatePressureDiffs(
-    ArrayRef<RegisterMaskPair> LiveUses) {
-  for (const RegisterMaskPair &P : LiveUses) {
+ 
+PostMachineScheduler::PostMachineScheduler() : MachineSchedulerBase(ID) { 
+  initializePostMachineSchedulerPass(*PassRegistry::getPassRegistry()); 
+} 
+ 
+void PostMachineScheduler::getAnalysisUsage(AnalysisUsage &AU) const { 
+  AU.setPreservesCFG(); 
+  AU.addRequired<MachineDominatorTree>(); 
+  AU.addRequired<MachineLoopInfo>(); 
+  AU.addRequired<AAResultsWrapperPass>(); 
+  AU.addRequired<TargetPassConfig>(); 
+  MachineFunctionPass::getAnalysisUsage(AU); 
+} 
+ 
+MachinePassRegistry<MachineSchedRegistry::ScheduleDAGCtor> 
+    MachineSchedRegistry::Registry; 
+ 
+/// A dummy default scheduler factory indicates whether the scheduler 
+/// is overridden on the command line. 
+static ScheduleDAGInstrs *useDefaultMachineSched(MachineSchedContext *C) { 
+  return nullptr; 
+} 
+ 
+/// MachineSchedOpt allows command line selection of the scheduler. 
+static cl::opt<MachineSchedRegistry::ScheduleDAGCtor, false, 
+               RegisterPassParser<MachineSchedRegistry>> 
+MachineSchedOpt("misched", 
+                cl::init(&useDefaultMachineSched), cl::Hidden, 
+                cl::desc("Machine instruction scheduler to use")); 
+ 
+static MachineSchedRegistry 
+DefaultSchedRegistry("default", "Use the target's default scheduler choice.", 
+                     useDefaultMachineSched); 
+ 
+static cl::opt<bool> EnableMachineSched( 
+    "enable-misched", 
+    cl::desc("Enable the machine instruction scheduling pass."), cl::init(true), 
+    cl::Hidden); 
+ 
+static cl::opt<bool> EnablePostRAMachineSched( 
+    "enable-post-misched", 
+    cl::desc("Enable the post-ra machine instruction scheduling pass."), 
+    cl::init(true), cl::Hidden); 
+ 
+/// Decrement this iterator until reaching the top or a non-debug instr. 
+static MachineBasicBlock::const_iterator 
+priorNonDebug(MachineBasicBlock::const_iterator I, 
+              MachineBasicBlock::const_iterator Beg) { 
+  assert(I != Beg && "reached the top of the region, cannot decrement"); 
+  while (--I != Beg) { 
+    if (!I->isDebugInstr()) 
+      break; 
+  } 
+  return I; 
+} 
+ 
+/// Non-const version. 
+static MachineBasicBlock::iterator 
+priorNonDebug(MachineBasicBlock::iterator I, 
+              MachineBasicBlock::const_iterator Beg) { 
+  return priorNonDebug(MachineBasicBlock::const_iterator(I), Beg) 
+      .getNonConstIterator(); 
+} 
+ 
+/// If this iterator is a debug value, increment until reaching the End or a 
+/// non-debug instruction. 
+static MachineBasicBlock::const_iterator 
+nextIfDebug(MachineBasicBlock::const_iterator I, 
+            MachineBasicBlock::const_iterator End) { 
+  for(; I != End; ++I) { 
+    if (!I->isDebugInstr()) 
+      break; 
+  } 
+  return I; 
+} 
+ 
+/// Non-const version. 
+static MachineBasicBlock::iterator 
+nextIfDebug(MachineBasicBlock::iterator I, 
+            MachineBasicBlock::const_iterator End) { 
+  return nextIfDebug(MachineBasicBlock::const_iterator(I), End) 
+      .getNonConstIterator(); 
+} 
+ 
+/// Instantiate a ScheduleDAGInstrs that will be owned by the caller. 
+ScheduleDAGInstrs *MachineScheduler::createMachineScheduler() { 
+  // Select the scheduler, or set the default. 
+  MachineSchedRegistry::ScheduleDAGCtor Ctor = MachineSchedOpt; 
+  if (Ctor != useDefaultMachineSched) 
+    return Ctor(this); 
+ 
+  // Get the default scheduler set by the target for this function. 
+  ScheduleDAGInstrs *Scheduler = PassConfig->createMachineScheduler(this); 
+  if (Scheduler) 
+    return Scheduler; 
+ 
+  // Default to GenericScheduler. 
+  return createGenericSchedLive(this); 
+} 
+ 
+/// Instantiate a ScheduleDAGInstrs for PostRA scheduling that will be owned by 
+/// the caller. We don't have a command line option to override the postRA 
+/// scheduler. The Target must configure it. 
+ScheduleDAGInstrs *PostMachineScheduler::createPostMachineScheduler() { 
+  // Get the postRA scheduler set by the target for this function. 
+  ScheduleDAGInstrs *Scheduler = PassConfig->createPostMachineScheduler(this); 
+  if (Scheduler) 
+    return Scheduler; 
+ 
+  // Default to GenericScheduler. 
+  return createGenericSchedPostRA(this); 
+} 
+ 
+/// Top-level MachineScheduler pass driver. 
+/// 
+/// Visit blocks in function order. Divide each block into scheduling regions 
+/// and visit them bottom-up. Visiting regions bottom-up is not required, but is 
+/// consistent with the DAG builder, which traverses the interior of the 
+/// scheduling regions bottom-up. 
+/// 
+/// This design avoids exposing scheduling boundaries to the DAG builder, 
+/// simplifying the DAG builder's support for "special" target instructions. 
+/// At the same time the design allows target schedulers to operate across 
+/// scheduling boundaries, for example to bundle the boundary instructions 
+/// without reordering them. This creates complexity, because the target 
+/// scheduler must update the RegionBegin and RegionEnd positions cached by 
+/// ScheduleDAGInstrs whenever adding or removing instructions. A much simpler 
+/// design would be to split blocks at scheduling boundaries, but LLVM has a 
+/// general bias against block splitting purely for implementation simplicity. 
+bool MachineScheduler::runOnMachineFunction(MachineFunction &mf) { 
+  if (skipFunction(mf.getFunction())) 
+    return false; 
+ 
+  if (EnableMachineSched.getNumOccurrences()) { 
+    if (!EnableMachineSched) 
+      return false; 
+  } else if (!mf.getSubtarget().enableMachineScheduler()) 
+    return false; 
+ 
+  LLVM_DEBUG(dbgs() << "Before MISched:\n"; mf.print(dbgs())); 
+ 
+  // Initialize the context of the pass. 
+  MF = &mf; 
+  MLI = &getAnalysis<MachineLoopInfo>(); 
+  MDT = &getAnalysis<MachineDominatorTree>(); 
+  PassConfig = &getAnalysis<TargetPassConfig>(); 
+  AA = &getAnalysis<AAResultsWrapperPass>().getAAResults(); 
+ 
+  LIS = &getAnalysis<LiveIntervals>(); 
+ 
+  if (VerifyScheduling) { 
+    LLVM_DEBUG(LIS->dump()); 
+    MF->verify(this, "Before machine scheduling."); 
+  } 
+  RegClassInfo->runOnMachineFunction(*MF); 
+ 
+  // Instantiate the selected scheduler for this target, function, and 
+  // optimization level. 
+  std::unique_ptr<ScheduleDAGInstrs> Scheduler(createMachineScheduler()); 
+  scheduleRegions(*Scheduler, false); 
+ 
+  LLVM_DEBUG(LIS->dump()); 
+  if (VerifyScheduling) 
+    MF->verify(this, "After machine scheduling."); 
+  return true; 
+} 
+ 
+bool PostMachineScheduler::runOnMachineFunction(MachineFunction &mf) { 
+  if (skipFunction(mf.getFunction())) 
+    return false; 
+ 
+  if (EnablePostRAMachineSched.getNumOccurrences()) { 
+    if (!EnablePostRAMachineSched) 
+      return false; 
+  } else if (!mf.getSubtarget().enablePostRAMachineScheduler()) { 
+    LLVM_DEBUG(dbgs() << "Subtarget disables post-MI-sched.\n"); 
+    return false; 
+  } 
+  LLVM_DEBUG(dbgs() << "Before post-MI-sched:\n"; mf.print(dbgs())); 
+ 
+  // Initialize the context of the pass. 
+  MF = &mf; 
+  MLI = &getAnalysis<MachineLoopInfo>(); 
+  PassConfig = &getAnalysis<TargetPassConfig>(); 
+  AA = &getAnalysis<AAResultsWrapperPass>().getAAResults(); 
+ 
+  if (VerifyScheduling) 
+    MF->verify(this, "Before post machine scheduling."); 
+ 
+  // Instantiate the selected scheduler for this target, function, and 
+  // optimization level. 
+  std::unique_ptr<ScheduleDAGInstrs> Scheduler(createPostMachineScheduler()); 
+  scheduleRegions(*Scheduler, true); 
+ 
+  if (VerifyScheduling) 
+    MF->verify(this, "After post machine scheduling."); 
+  return true; 
+} 
+ 
+/// Return true of the given instruction should not be included in a scheduling 
+/// region. 
+/// 
+/// MachineScheduler does not currently support scheduling across calls. To 
+/// handle calls, the DAG builder needs to be modified to create register 
+/// anti/output dependencies on the registers clobbered by the call's regmask 
+/// operand. In PreRA scheduling, the stack pointer adjustment already prevents 
+/// scheduling across calls. In PostRA scheduling, we need the isCall to enforce 
+/// the boundary, but there would be no benefit to postRA scheduling across 
+/// calls this late anyway. 
+static bool isSchedBoundary(MachineBasicBlock::iterator MI, 
+                            MachineBasicBlock *MBB, 
+                            MachineFunction *MF, 
+                            const TargetInstrInfo *TII) { 
+  return MI->isCall() || TII->isSchedulingBoundary(*MI, MBB, *MF); 
+} 
+ 
+/// A region of an MBB for scheduling. 
+namespace { 
+struct SchedRegion { 
+  /// RegionBegin is the first instruction in the scheduling region, and 
+  /// RegionEnd is either MBB->end() or the scheduling boundary after the 
+  /// last instruction in the scheduling region. These iterators cannot refer 
+  /// to instructions outside of the identified scheduling region because 
+  /// those may be reordered before scheduling this region. 
+  MachineBasicBlock::iterator RegionBegin; 
+  MachineBasicBlock::iterator RegionEnd; 
+  unsigned NumRegionInstrs; 
+ 
+  SchedRegion(MachineBasicBlock::iterator B, MachineBasicBlock::iterator E, 
+              unsigned N) : 
+    RegionBegin(B), RegionEnd(E), NumRegionInstrs(N) {} 
+}; 
+} // end anonymous namespace 
+ 
+using MBBRegionsVector = SmallVector<SchedRegion, 16>; 
+ 
+static void 
+getSchedRegions(MachineBasicBlock *MBB, 
+                MBBRegionsVector &Regions, 
+                bool RegionsTopDown) { 
+  MachineFunction *MF = MBB->getParent(); 
+  const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo(); 
+ 
+  MachineBasicBlock::iterator I = nullptr; 
+  for(MachineBasicBlock::iterator RegionEnd = MBB->end(); 
+      RegionEnd != MBB->begin(); RegionEnd = I) { 
+ 
+    // Avoid decrementing RegionEnd for blocks with no terminator. 
+    if (RegionEnd != MBB->end() || 
+        isSchedBoundary(&*std::prev(RegionEnd), &*MBB, MF, TII)) { 
+      --RegionEnd; 
+    } 
+ 
+    // The next region starts above the previous region. Look backward in the 
+    // instruction stream until we find the nearest boundary. 
+    unsigned NumRegionInstrs = 0; 
+    I = RegionEnd; 
+    for (;I != MBB->begin(); --I) { 
+      MachineInstr &MI = *std::prev(I); 
+      if (isSchedBoundary(&MI, &*MBB, MF, TII)) 
+        break; 
+      if (!MI.isDebugInstr()) { 
+        // MBB::size() uses instr_iterator to count. Here we need a bundle to 
+        // count as a single instruction. 
+        ++NumRegionInstrs; 
+      } 
+    } 
+ 
+    // It's possible we found a scheduling region that only has debug 
+    // instructions. Don't bother scheduling these. 
+    if (NumRegionInstrs != 0) 
+      Regions.push_back(SchedRegion(I, RegionEnd, NumRegionInstrs)); 
+  } 
+ 
+  if (RegionsTopDown) 
+    std::reverse(Regions.begin(), Regions.end()); 
+} 
+ 
+/// Main driver for both MachineScheduler and PostMachineScheduler. 
+void MachineSchedulerBase::scheduleRegions(ScheduleDAGInstrs &Scheduler, 
+                                           bool FixKillFlags) { 
+  // Visit all machine basic blocks. 
+  // 
+  // TODO: Visit blocks in global postorder or postorder within the bottom-up 
+  // loop tree. Then we can optionally compute global RegPressure. 
+  for (MachineFunction::iterator MBB = MF->begin(), MBBEnd = MF->end(); 
+       MBB != MBBEnd; ++MBB) { 
+ 
+    Scheduler.startBlock(&*MBB); 
+ 
+#ifndef NDEBUG 
+    if (SchedOnlyFunc.getNumOccurrences() && SchedOnlyFunc != MF->getName()) 
+      continue; 
+    if (SchedOnlyBlock.getNumOccurrences() 
+        && (int)SchedOnlyBlock != MBB->getNumber()) 
+      continue; 
+#endif 
+ 
+    // Break the block into scheduling regions [I, RegionEnd). RegionEnd 
+    // points to the scheduling boundary at the bottom of the region. The DAG 
+    // does not include RegionEnd, but the region does (i.e. the next 
+    // RegionEnd is above the previous RegionBegin). If the current block has 
+    // no terminator then RegionEnd == MBB->end() for the bottom region. 
+    // 
+    // All the regions of MBB are first found and stored in MBBRegions, which 
+    // will be processed (MBB) top-down if initialized with true. 
+    // 
+    // The Scheduler may insert instructions during either schedule() or 
+    // exitRegion(), even for empty regions. So the local iterators 'I' and 
+    // 'RegionEnd' are invalid across these calls. Instructions must not be 
+    // added to other regions than the current one without updating MBBRegions. 
+ 
+    MBBRegionsVector MBBRegions; 
+    getSchedRegions(&*MBB, MBBRegions, Scheduler.doMBBSchedRegionsTopDown()); 
+    for (MBBRegionsVector::iterator R = MBBRegions.begin(); 
+         R != MBBRegions.end(); ++R) { 
+      MachineBasicBlock::iterator I = R->RegionBegin; 
+      MachineBasicBlock::iterator RegionEnd = R->RegionEnd; 
+      unsigned NumRegionInstrs = R->NumRegionInstrs; 
+ 
+      // Notify the scheduler of the region, even if we may skip scheduling 
+      // it. Perhaps it still needs to be bundled. 
+      Scheduler.enterRegion(&*MBB, I, RegionEnd, NumRegionInstrs); 
+ 
+      // Skip empty scheduling regions (0 or 1 schedulable instructions). 
+      if (I == RegionEnd || I == std::prev(RegionEnd)) { 
+        // Close the current region. Bundle the terminator if needed. 
+        // This invalidates 'RegionEnd' and 'I'. 
+        Scheduler.exitRegion(); 
+        continue; 
+      } 
+      LLVM_DEBUG(dbgs() << "********** MI Scheduling **********\n"); 
+      LLVM_DEBUG(dbgs() << MF->getName() << ":" << printMBBReference(*MBB) 
+                        << " " << MBB->getName() << "\n  From: " << *I 
+                        << "    To: "; 
+                 if (RegionEnd != MBB->end()) dbgs() << *RegionEnd; 
+                 else dbgs() << "End"; 
+                 dbgs() << " RegionInstrs: " << NumRegionInstrs << '\n'); 
+      if (DumpCriticalPathLength) { 
+        errs() << MF->getName(); 
+        errs() << ":%bb. " << MBB->getNumber(); 
+        errs() << " " << MBB->getName() << " \n"; 
+      } 
+ 
+      // Schedule a region: possibly reorder instructions. 
+      // This invalidates the original region iterators. 
+      Scheduler.schedule(); 
+ 
+      // Close the current region. 
+      Scheduler.exitRegion(); 
+    } 
+    Scheduler.finishBlock(); 
+    // FIXME: Ideally, no further passes should rely on kill flags. However, 
+    // thumb2 size reduction is currently an exception, so the PostMIScheduler 
+    // needs to do this. 
+    if (FixKillFlags) 
+      Scheduler.fixupKills(*MBB); 
+  } 
+  Scheduler.finalizeSchedule(); 
+} 
+ 
+void MachineSchedulerBase::print(raw_ostream &O, const Module* m) const { 
+  // unimplemented 
+} 
+ 
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 
+LLVM_DUMP_METHOD void ReadyQueue::dump() const { 
+  dbgs() << "Queue " << Name << ": "; 
+  for (const SUnit *SU : Queue) 
+    dbgs() << SU->NodeNum << " "; 
+  dbgs() << "\n"; 
+} 
+#endif 
+ 
+//===----------------------------------------------------------------------===// 
+// ScheduleDAGMI - Basic machine instruction scheduling. This is 
+// independent of PreRA/PostRA scheduling and involves no extra book-keeping for 
+// virtual registers. 
+// ===----------------------------------------------------------------------===/ 
+ 
+// Provide a vtable anchor. 
+ScheduleDAGMI::~ScheduleDAGMI() = default; 
+ 
+/// ReleaseSucc - Decrement the NumPredsLeft count of a successor. When 
+/// NumPredsLeft reaches zero, release the successor node. 
+/// 
+/// FIXME: Adjust SuccSU height based on MinLatency. 
+void ScheduleDAGMI::releaseSucc(SUnit *SU, SDep *SuccEdge) { 
+  SUnit *SuccSU = SuccEdge->getSUnit(); 
+ 
+  if (SuccEdge->isWeak()) { 
+    --SuccSU->WeakPredsLeft; 
+    if (SuccEdge->isCluster()) 
+      NextClusterSucc = SuccSU; 
+    return; 
+  } 
+#ifndef NDEBUG 
+  if (SuccSU->NumPredsLeft == 0) { 
+    dbgs() << "*** Scheduling failed! ***\n"; 
+    dumpNode(*SuccSU); 
+    dbgs() << " has been released too many times!\n"; 
+    llvm_unreachable(nullptr); 
+  } 
+#endif 
+  // SU->TopReadyCycle was set to CurrCycle when it was scheduled. However, 
+  // CurrCycle may have advanced since then. 
+  if (SuccSU->TopReadyCycle < SU->TopReadyCycle + SuccEdge->getLatency()) 
+    SuccSU->TopReadyCycle = SU->TopReadyCycle + SuccEdge->getLatency(); 
+ 
+  --SuccSU->NumPredsLeft; 
+  if (SuccSU->NumPredsLeft == 0 && SuccSU != &ExitSU) 
+    SchedImpl->releaseTopNode(SuccSU); 
+} 
+ 
+/// releaseSuccessors - Call releaseSucc on each of SU's successors. 
+void ScheduleDAGMI::releaseSuccessors(SUnit *SU) { 
+  for (SDep &Succ : SU->Succs) 
+    releaseSucc(SU, &Succ); 
+} 
+ 
+/// ReleasePred - Decrement the NumSuccsLeft count of a predecessor. When 
+/// NumSuccsLeft reaches zero, release the predecessor node. 
+/// 
+/// FIXME: Adjust PredSU height based on MinLatency. 
+void ScheduleDAGMI::releasePred(SUnit *SU, SDep *PredEdge) { 
+  SUnit *PredSU = PredEdge->getSUnit(); 
+ 
+  if (PredEdge->isWeak()) { 
+    --PredSU->WeakSuccsLeft; 
+    if (PredEdge->isCluster()) 
+      NextClusterPred = PredSU; 
+    return; 
+  } 
+#ifndef NDEBUG 
+  if (PredSU->NumSuccsLeft == 0) { 
+    dbgs() << "*** Scheduling failed! ***\n"; 
+    dumpNode(*PredSU); 
+    dbgs() << " has been released too many times!\n"; 
+    llvm_unreachable(nullptr); 
+  } 
+#endif 
+  // SU->BotReadyCycle was set to CurrCycle when it was scheduled. However, 
+  // CurrCycle may have advanced since then. 
+  if (PredSU->BotReadyCycle < SU->BotReadyCycle + PredEdge->getLatency()) 
+    PredSU->BotReadyCycle = SU->BotReadyCycle + PredEdge->getLatency(); 
+ 
+  --PredSU->NumSuccsLeft; 
+  if (PredSU->NumSuccsLeft == 0 && PredSU != &EntrySU) 
+    SchedImpl->releaseBottomNode(PredSU); 
+} 
+ 
+/// releasePredecessors - Call releasePred on each of SU's predecessors. 
+void ScheduleDAGMI::releasePredecessors(SUnit *SU) { 
+  for (SDep &Pred : SU->Preds) 
+    releasePred(SU, &Pred); 
+} 
+ 
+void ScheduleDAGMI::startBlock(MachineBasicBlock *bb) { 
+  ScheduleDAGInstrs::startBlock(bb); 
+  SchedImpl->enterMBB(bb); 
+} 
+ 
+void ScheduleDAGMI::finishBlock() { 
+  SchedImpl->leaveMBB(); 
+  ScheduleDAGInstrs::finishBlock(); 
+} 
+ 
+/// enterRegion - Called back from MachineScheduler::runOnMachineFunction after 
+/// crossing a scheduling boundary. [begin, end) includes all instructions in 
+/// the region, including the boundary itself and single-instruction regions 
+/// that don't get scheduled. 
+void ScheduleDAGMI::enterRegion(MachineBasicBlock *bb, 
+                                     MachineBasicBlock::iterator begin, 
+                                     MachineBasicBlock::iterator end, 
+                                     unsigned regioninstrs) 
+{ 
+  ScheduleDAGInstrs::enterRegion(bb, begin, end, regioninstrs); 
+ 
+  SchedImpl->initPolicy(begin, end, regioninstrs); 
+} 
+ 
+/// This is normally called from the main scheduler loop but may also be invoked 
+/// by the scheduling strategy to perform additional code motion. 
+void ScheduleDAGMI::moveInstruction( 
+  MachineInstr *MI, MachineBasicBlock::iterator InsertPos) { 
+  // Advance RegionBegin if the first instruction moves down. 
+  if (&*RegionBegin == MI) 
+    ++RegionBegin; 
+ 
+  // Update the instruction stream. 
+  BB->splice(InsertPos, BB, MI); 
+ 
+  // Update LiveIntervals 
+  if (LIS) 
+    LIS->handleMove(*MI, /*UpdateFlags=*/true); 
+ 
+  // Recede RegionBegin if an instruction moves above the first. 
+  if (RegionBegin == InsertPos) 
+    RegionBegin = MI; 
+} 
+ 
+bool ScheduleDAGMI::checkSchedLimit() { 
+#ifndef NDEBUG 
+  if (NumInstrsScheduled == MISchedCutoff && MISchedCutoff != ~0U) { 
+    CurrentTop = CurrentBottom; 
+    return false; 
+  } 
+  ++NumInstrsScheduled; 
+#endif 
+  return true; 
+} 
+ 
+/// Per-region scheduling driver, called back from 
+/// MachineScheduler::runOnMachineFunction. This is a simplified driver that 
+/// does not consider liveness or register pressure. It is useful for PostRA 
+/// scheduling and potentially other custom schedulers. 
+void ScheduleDAGMI::schedule() { 
+  LLVM_DEBUG(dbgs() << "ScheduleDAGMI::schedule starting\n"); 
+  LLVM_DEBUG(SchedImpl->dumpPolicy()); 
+ 
+  // Build the DAG. 
+  buildSchedGraph(AA); 
+ 
+  postprocessDAG(); 
+ 
+  SmallVector<SUnit*, 8> TopRoots, BotRoots; 
+  findRootsAndBiasEdges(TopRoots, BotRoots); 
+ 
+  LLVM_DEBUG(dump()); 
+  if (PrintDAGs) dump(); 
+  if (ViewMISchedDAGs) viewGraph(); 
+ 
+  // Initialize the strategy before modifying the DAG. 
+  // This may initialize a DFSResult to be used for queue priority. 
+  SchedImpl->initialize(this); 
+ 
+  // Initialize ready queues now that the DAG and priority data are finalized. 
+  initQueues(TopRoots, BotRoots); 
+ 
+  bool IsTopNode = false; 
+  while (true) { 
+    LLVM_DEBUG(dbgs() << "** ScheduleDAGMI::schedule picking next node\n"); 
+    SUnit *SU = SchedImpl->pickNode(IsTopNode); 
+    if (!SU) break; 
+ 
+    assert(!SU->isScheduled && "Node already scheduled"); 
+    if (!checkSchedLimit()) 
+      break; 
+ 
+    MachineInstr *MI = SU->getInstr(); 
+    if (IsTopNode) { 
+      assert(SU->isTopReady() && "node still has unscheduled dependencies"); 
+      if (&*CurrentTop == MI) 
+        CurrentTop = nextIfDebug(++CurrentTop, CurrentBottom); 
+      else 
+        moveInstruction(MI, CurrentTop); 
+    } else { 
+      assert(SU->isBottomReady() && "node still has unscheduled dependencies"); 
+      MachineBasicBlock::iterator priorII = 
+        priorNonDebug(CurrentBottom, CurrentTop); 
+      if (&*priorII == MI) 
+        CurrentBottom = priorII; 
+      else { 
+        if (&*CurrentTop == MI) 
+          CurrentTop = nextIfDebug(++CurrentTop, priorII); 
+        moveInstruction(MI, CurrentBottom); 
+        CurrentBottom = MI; 
+      } 
+    } 
+    // Notify the scheduling strategy before updating the DAG. 
+    // This sets the scheduled node's ReadyCycle to CurrCycle. When updateQueues 
+    // runs, it can then use the accurate ReadyCycle time to determine whether 
+    // newly released nodes can move to the readyQ. 
+    SchedImpl->schedNode(SU, IsTopNode); 
+ 
+    updateQueues(SU, IsTopNode); 
+  } 
+  assert(CurrentTop == CurrentBottom && "Nonempty unscheduled zone."); 
+ 
+  placeDebugValues(); 
+ 
+  LLVM_DEBUG({ 
+    dbgs() << "*** Final schedule for " 
+           << printMBBReference(*begin()->getParent()) << " ***\n"; 
+    dumpSchedule(); 
+    dbgs() << '\n'; 
+  }); 
+} 
+ 
+/// Apply each ScheduleDAGMutation step in order. 
+void ScheduleDAGMI::postprocessDAG() { 
+  for (auto &m : Mutations) 
+    m->apply(this); 
+} 
+ 
+void ScheduleDAGMI:: 
+findRootsAndBiasEdges(SmallVectorImpl<SUnit*> &TopRoots, 
+                      SmallVectorImpl<SUnit*> &BotRoots) { 
+  for (SUnit &SU : SUnits) { 
+    assert(!SU.isBoundaryNode() && "Boundary node should not be in SUnits"); 
+ 
+    // Order predecessors so DFSResult follows the critical path. 
+    SU.biasCriticalPath(); 
+ 
+    // A SUnit is ready to top schedule if it has no predecessors. 
+    if (!SU.NumPredsLeft) 
+      TopRoots.push_back(&SU); 
+    // A SUnit is ready to bottom schedule if it has no successors. 
+    if (!SU.NumSuccsLeft) 
+      BotRoots.push_back(&SU); 
+  } 
+  ExitSU.biasCriticalPath(); 
+} 
+ 
+/// Identify DAG roots and setup scheduler queues. 
+void ScheduleDAGMI::initQueues(ArrayRef<SUnit*> TopRoots, 
+                               ArrayRef<SUnit*> BotRoots) { 
+  NextClusterSucc = nullptr; 
+  NextClusterPred = nullptr; 
+ 
+  // Release all DAG roots for scheduling, not including EntrySU/ExitSU. 
+  // 
+  // Nodes with unreleased weak edges can still be roots. 
+  // Release top roots in forward order. 
+  for (SUnit *SU : TopRoots) 
+    SchedImpl->releaseTopNode(SU); 
+ 
+  // Release bottom roots in reverse order so the higher priority nodes appear 
+  // first. This is more natural and slightly more efficient. 
+  for (SmallVectorImpl<SUnit*>::const_reverse_iterator 
+         I = BotRoots.rbegin(), E = BotRoots.rend(); I != E; ++I) { 
+    SchedImpl->releaseBottomNode(*I); 
+  } 
+ 
+  releaseSuccessors(&EntrySU); 
+  releasePredecessors(&ExitSU); 
+ 
+  SchedImpl->registerRoots(); 
+ 
+  // Advance past initial DebugValues. 
+  CurrentTop = nextIfDebug(RegionBegin, RegionEnd); 
+  CurrentBottom = RegionEnd; 
+} 
+ 
+/// Update scheduler queues after scheduling an instruction. 
+void ScheduleDAGMI::updateQueues(SUnit *SU, bool IsTopNode) { 
+  // Release dependent instructions for scheduling. 
+  if (IsTopNode) 
+    releaseSuccessors(SU); 
+  else 
+    releasePredecessors(SU); 
+ 
+  SU->isScheduled = true; 
+} 
+ 
+/// Reinsert any remaining debug_values, just like the PostRA scheduler. 
+void ScheduleDAGMI::placeDebugValues() { 
+  // If first instruction was a DBG_VALUE then put it back. 
+  if (FirstDbgValue) { 
+    BB->splice(RegionBegin, BB, FirstDbgValue); 
+    RegionBegin = FirstDbgValue; 
+  } 
+ 
+  for (std::vector<std::pair<MachineInstr *, MachineInstr *>>::iterator 
+         DI = DbgValues.end(), DE = DbgValues.begin(); DI != DE; --DI) { 
+    std::pair<MachineInstr *, MachineInstr *> P = *std::prev(DI); 
+    MachineInstr *DbgValue = P.first; 
+    MachineBasicBlock::iterator OrigPrevMI = P.second; 
+    if (&*RegionBegin == DbgValue) 
+      ++RegionBegin; 
+    BB->splice(++OrigPrevMI, BB, DbgValue); 
+    if (OrigPrevMI == std::prev(RegionEnd)) 
+      RegionEnd = DbgValue; 
+  } 
+  DbgValues.clear(); 
+  FirstDbgValue = nullptr; 
+} 
+ 
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 
+LLVM_DUMP_METHOD void ScheduleDAGMI::dumpSchedule() const { 
+  for (MachineBasicBlock::iterator MI = begin(), ME = end(); MI != ME; ++MI) { 
+    if (SUnit *SU = getSUnit(&(*MI))) 
+      dumpNode(*SU); 
+    else 
+      dbgs() << "Missing SUnit\n"; 
+  } 
+} 
+#endif 
+ 
+//===----------------------------------------------------------------------===// 
+// ScheduleDAGMILive - Base class for MachineInstr scheduling with LiveIntervals 
+// preservation. 
+//===----------------------------------------------------------------------===// 
+ 
+ScheduleDAGMILive::~ScheduleDAGMILive() { 
+  delete DFSResult; 
+} 
+ 
+void ScheduleDAGMILive::collectVRegUses(SUnit &SU) { 
+  const MachineInstr &MI = *SU.getInstr(); 
+  for (const MachineOperand &MO : MI.operands()) { 
+    if (!MO.isReg()) 
+      continue; 
+    if (!MO.readsReg()) 
+      continue; 
+    if (TrackLaneMasks && !MO.isUse()) 
+      continue; 
+ 
+    Register Reg = MO.getReg(); 
+    if (!Register::isVirtualRegister(Reg)) 
+      continue; 
+ 
+    // Ignore re-defs. 
+    if (TrackLaneMasks) { 
+      bool FoundDef = false; 
+      for (const MachineOperand &MO2 : MI.operands()) { 
+        if (MO2.isReg() && MO2.isDef() && MO2.getReg() == Reg && !MO2.isDead()) { 
+          FoundDef = true; 
+          break; 
+        } 
+      } 
+      if (FoundDef) 
+        continue; 
+    } 
+ 
+    // Record this local VReg use. 
+    VReg2SUnitMultiMap::iterator UI = VRegUses.find(Reg); 
+    for (; UI != VRegUses.end(); ++UI) { 
+      if (UI->SU == &SU) 
+        break; 
+    } 
+    if (UI == VRegUses.end()) 
+      VRegUses.insert(VReg2SUnit(Reg, LaneBitmask::getNone(), &SU)); 
+  } 
+} 
+ 
+/// enterRegion - Called back from MachineScheduler::runOnMachineFunction after 
+/// crossing a scheduling boundary. [begin, end) includes all instructions in 
+/// the region, including the boundary itself and single-instruction regions 
+/// that don't get scheduled. 
+void ScheduleDAGMILive::enterRegion(MachineBasicBlock *bb, 
+                                MachineBasicBlock::iterator begin, 
+                                MachineBasicBlock::iterator end, 
+                                unsigned regioninstrs) 
+{ 
+  // ScheduleDAGMI initializes SchedImpl's per-region policy. 
+  ScheduleDAGMI::enterRegion(bb, begin, end, regioninstrs); 
+ 
+  // For convenience remember the end of the liveness region. 
+  LiveRegionEnd = (RegionEnd == bb->end()) ? RegionEnd : std::next(RegionEnd); 
+ 
+  SUPressureDiffs.clear(); 
+ 
+  ShouldTrackPressure = SchedImpl->shouldTrackPressure(); 
+  ShouldTrackLaneMasks = SchedImpl->shouldTrackLaneMasks(); 
+ 
+  assert((!ShouldTrackLaneMasks || ShouldTrackPressure) && 
+         "ShouldTrackLaneMasks requires ShouldTrackPressure"); 
+} 
+ 
+// Setup the register pressure trackers for the top scheduled and bottom 
+// scheduled regions. 
+void ScheduleDAGMILive::initRegPressure() { 
+  VRegUses.clear(); 
+  VRegUses.setUniverse(MRI.getNumVirtRegs()); 
+  for (SUnit &SU : SUnits) 
+    collectVRegUses(SU); 
+ 
+  TopRPTracker.init(&MF, RegClassInfo, LIS, BB, RegionBegin, 
+                    ShouldTrackLaneMasks, false); 
+  BotRPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd, 
+                    ShouldTrackLaneMasks, false); 
+ 
+  // Close the RPTracker to finalize live ins. 
+  RPTracker.closeRegion(); 
+ 
+  LLVM_DEBUG(RPTracker.dump()); 
+ 
+  // Initialize the live ins and live outs. 
+  TopRPTracker.addLiveRegs(RPTracker.getPressure().LiveInRegs); 
+  BotRPTracker.addLiveRegs(RPTracker.getPressure().LiveOutRegs); 
+ 
+  // Close one end of the tracker so we can call 
+  // getMaxUpward/DownwardPressureDelta before advancing across any 
+  // instructions. This converts currently live regs into live ins/outs. 
+  TopRPTracker.closeTop(); 
+  BotRPTracker.closeBottom(); 
+ 
+  BotRPTracker.initLiveThru(RPTracker); 
+  if (!BotRPTracker.getLiveThru().empty()) { 
+    TopRPTracker.initLiveThru(BotRPTracker.getLiveThru()); 
+    LLVM_DEBUG(dbgs() << "Live Thru: "; 
+               dumpRegSetPressure(BotRPTracker.getLiveThru(), TRI)); 
+  }; 
+ 
+  // For each live out vreg reduce the pressure change associated with other 
+  // uses of the same vreg below the live-out reaching def. 
+  updatePressureDiffs(RPTracker.getPressure().LiveOutRegs); 
+ 
+  // Account for liveness generated by the region boundary. 
+  if (LiveRegionEnd != RegionEnd) { 
+    SmallVector<RegisterMaskPair, 8> LiveUses; 
+    BotRPTracker.recede(&LiveUses); 
+    updatePressureDiffs(LiveUses); 
+  } 
+ 
+  LLVM_DEBUG(dbgs() << "Top Pressure:\n"; 
+             dumpRegSetPressure(TopRPTracker.getRegSetPressureAtPos(), TRI); 
+             dbgs() << "Bottom Pressure:\n"; 
+             dumpRegSetPressure(BotRPTracker.getRegSetPressureAtPos(), TRI);); 
+ 
+  assert((BotRPTracker.getPos() == RegionEnd || 
+          (RegionEnd->isDebugInstr() && 
+           BotRPTracker.getPos() == priorNonDebug(RegionEnd, RegionBegin))) && 
+         "Can't find the region bottom"); 
+ 
+  // Cache the list of excess pressure sets in this region. This will also track 
+  // the max pressure in the scheduled code for these sets. 
+  RegionCriticalPSets.clear(); 
+  const std::vector<unsigned> &RegionPressure = 
+    RPTracker.getPressure().MaxSetPressure; 
+  for (unsigned i = 0, e = RegionPressure.size(); i < e; ++i) { 
+    unsigned Limit = RegClassInfo->getRegPressureSetLimit(i); 
+    if (RegionPressure[i] > Limit) { 
+      LLVM_DEBUG(dbgs() << TRI->getRegPressureSetName(i) << " Limit " << Limit 
+                        << " Actual " << RegionPressure[i] << "\n"); 
+      RegionCriticalPSets.push_back(PressureChange(i)); 
+    } 
+  } 
+  LLVM_DEBUG(dbgs() << "Excess PSets: "; 
+             for (const PressureChange &RCPS 
+                  : RegionCriticalPSets) dbgs() 
+             << TRI->getRegPressureSetName(RCPS.getPSet()) << " "; 
+             dbgs() << "\n"); 
+} 
+ 
+void ScheduleDAGMILive:: 
+updateScheduledPressure(const SUnit *SU, 
+                        const std::vector<unsigned> &NewMaxPressure) { 
+  const PressureDiff &PDiff = getPressureDiff(SU); 
+  unsigned CritIdx = 0, CritEnd = RegionCriticalPSets.size(); 
+  for (const PressureChange &PC : PDiff) { 
+    if (!PC.isValid()) 
+      break; 
+    unsigned ID = PC.getPSet(); 
+    while (CritIdx != CritEnd && RegionCriticalPSets[CritIdx].getPSet() < ID) 
+      ++CritIdx; 
+    if (CritIdx != CritEnd && RegionCriticalPSets[CritIdx].getPSet() == ID) { 
+      if ((int)NewMaxPressure[ID] > RegionCriticalPSets[CritIdx].getUnitInc() 
+          && NewMaxPressure[ID] <= (unsigned)std::numeric_limits<int16_t>::max()) 
+        RegionCriticalPSets[CritIdx].setUnitInc(NewMaxPressure[ID]); 
+    } 
+    unsigned Limit = RegClassInfo->getRegPressureSetLimit(ID); 
+    if (NewMaxPressure[ID] >= Limit - 2) { 
+      LLVM_DEBUG(dbgs() << "  " << TRI->getRegPressureSetName(ID) << ": " 
+                        << NewMaxPressure[ID] 
+                        << ((NewMaxPressure[ID] > Limit) ? " > " : " <= ") 
+                        << Limit << "(+ " << BotRPTracker.getLiveThru()[ID] 
+                        << " livethru)\n"); 
+    } 
+  } 
+} 
+ 
+/// Update the PressureDiff array for liveness after scheduling this 
+/// instruction. 
+void ScheduleDAGMILive::updatePressureDiffs( 
+    ArrayRef<RegisterMaskPair> LiveUses) { 
+  for (const RegisterMaskPair &P : LiveUses) { 
     Register Reg = P.RegUnit;
-    /// FIXME: Currently assuming single-use physregs.
-    if (!Register::isVirtualRegister(Reg))
-      continue;
-
-    if (ShouldTrackLaneMasks) {
-      // If the register has just become live then other uses won't change
-      // this fact anymore => decrement pressure.
-      // If the register has just become dead then other uses make it come
-      // back to life => increment pressure.
-      bool Decrement = P.LaneMask.any();
-
-      for (const VReg2SUnit &V2SU
-           : make_range(VRegUses.find(Reg), VRegUses.end())) {
-        SUnit &SU = *V2SU.SU;
-        if (SU.isScheduled || &SU == &ExitSU)
-          continue;
-
-        PressureDiff &PDiff = getPressureDiff(&SU);
-        PDiff.addPressureChange(Reg, Decrement, &MRI);
-        LLVM_DEBUG(dbgs() << "  UpdateRegP: SU(" << SU.NodeNum << ") "
-                          << printReg(Reg, TRI) << ':'
-                          << PrintLaneMask(P.LaneMask) << ' ' << *SU.getInstr();
-                   dbgs() << "              to "; PDiff.dump(*TRI););
-      }
-    } else {
-      assert(P.LaneMask.any());
-      LLVM_DEBUG(dbgs() << "  LiveReg: " << printVRegOrUnit(Reg, TRI) << "\n");
-      // This may be called before CurrentBottom has been initialized. However,
-      // BotRPTracker must have a valid position. We want the value live into the
-      // instruction or live out of the block, so ask for the previous
-      // instruction's live-out.
-      const LiveInterval &LI = LIS->getInterval(Reg);
-      VNInfo *VNI;
-      MachineBasicBlock::const_iterator I =
-        nextIfDebug(BotRPTracker.getPos(), BB->end());
-      if (I == BB->end())
-        VNI = LI.getVNInfoBefore(LIS->getMBBEndIdx(BB));
-      else {
-        LiveQueryResult LRQ = LI.Query(LIS->getInstructionIndex(*I));
-        VNI = LRQ.valueIn();
-      }
-      // RegisterPressureTracker guarantees that readsReg is true for LiveUses.
-      assert(VNI && "No live value at use.");
-      for (const VReg2SUnit &V2SU
-           : make_range(VRegUses.find(Reg), VRegUses.end())) {
-        SUnit *SU = V2SU.SU;
-        // If this use comes before the reaching def, it cannot be a last use,
-        // so decrease its pressure change.
-        if (!SU->isScheduled && SU != &ExitSU) {
-          LiveQueryResult LRQ =
-              LI.Query(LIS->getInstructionIndex(*SU->getInstr()));
-          if (LRQ.valueIn() == VNI) {
-            PressureDiff &PDiff = getPressureDiff(SU);
-            PDiff.addPressureChange(Reg, true, &MRI);
-            LLVM_DEBUG(dbgs() << "  UpdateRegP: SU(" << SU->NodeNum << ") "
-                              << *SU->getInstr();
-                       dbgs() << "              to "; PDiff.dump(*TRI););
-          }
-        }
-      }
-    }
-  }
-}
-
-void ScheduleDAGMILive::dump() const {
-#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-  if (EntrySU.getInstr() != nullptr)
-    dumpNodeAll(EntrySU);
-  for (const SUnit &SU : SUnits) {
-    dumpNodeAll(SU);
-    if (ShouldTrackPressure) {
-      dbgs() << "  Pressure Diff      : ";
-      getPressureDiff(&SU).dump(*TRI);
-    }
-    dbgs() << "  Single Issue       : ";
-    if (SchedModel.mustBeginGroup(SU.getInstr()) &&
-        SchedModel.mustEndGroup(SU.getInstr()))
-      dbgs() << "true;";
-    else
-      dbgs() << "false;";
-    dbgs() << '\n';
-  }
-  if (ExitSU.getInstr() != nullptr)
-    dumpNodeAll(ExitSU);
-#endif
-}
-
-/// schedule - Called back from MachineScheduler::runOnMachineFunction
-/// after setting up the current scheduling region. [RegionBegin, RegionEnd)
-/// only includes instructions that have DAG nodes, not scheduling boundaries.
-///
-/// This is a skeletal driver, with all the functionality pushed into helpers,
-/// so that it can be easily extended by experimental schedulers. Generally,
-/// implementing MachineSchedStrategy should be sufficient to implement a new
-/// scheduling algorithm. However, if a scheduler further subclasses
-/// ScheduleDAGMILive then it will want to override this virtual method in order
-/// to update any specialized state.
-void ScheduleDAGMILive::schedule() {
-  LLVM_DEBUG(dbgs() << "ScheduleDAGMILive::schedule starting\n");
-  LLVM_DEBUG(SchedImpl->dumpPolicy());
-  buildDAGWithRegPressure();
-
-  postprocessDAG();
-
-  SmallVector<SUnit*, 8> TopRoots, BotRoots;
-  findRootsAndBiasEdges(TopRoots, BotRoots);
-
-  // Initialize the strategy before modifying the DAG.
-  // This may initialize a DFSResult to be used for queue priority.
-  SchedImpl->initialize(this);
-
-  LLVM_DEBUG(dump());
-  if (PrintDAGs) dump();
-  if (ViewMISchedDAGs) viewGraph();
-
-  // Initialize ready queues now that the DAG and priority data are finalized.
-  initQueues(TopRoots, BotRoots);
-
-  bool IsTopNode = false;
-  while (true) {
-    LLVM_DEBUG(dbgs() << "** ScheduleDAGMILive::schedule picking next node\n");
-    SUnit *SU = SchedImpl->pickNode(IsTopNode);
-    if (!SU) break;
-
-    assert(!SU->isScheduled && "Node already scheduled");
-    if (!checkSchedLimit())
-      break;
-
-    scheduleMI(SU, IsTopNode);
-
-    if (DFSResult) {
-      unsigned SubtreeID = DFSResult->getSubtreeID(SU);
-      if (!ScheduledTrees.test(SubtreeID)) {
-        ScheduledTrees.set(SubtreeID);
-        DFSResult->scheduleTree(SubtreeID);
-        SchedImpl->scheduleTree(SubtreeID);
-      }
-    }
-
-    // Notify the scheduling strategy after updating the DAG.
-    SchedImpl->schedNode(SU, IsTopNode);
-
-    updateQueues(SU, IsTopNode);
-  }
-  assert(CurrentTop == CurrentBottom && "Nonempty unscheduled zone.");
-
-  placeDebugValues();
-
-  LLVM_DEBUG({
-    dbgs() << "*** Final schedule for "
-           << printMBBReference(*begin()->getParent()) << " ***\n";
-    dumpSchedule();
-    dbgs() << '\n';
-  });
-}
-
-/// Build the DAG and setup three register pressure trackers.
-void ScheduleDAGMILive::buildDAGWithRegPressure() {
-  if (!ShouldTrackPressure) {
-    RPTracker.reset();
-    RegionCriticalPSets.clear();
-    buildSchedGraph(AA);
-    return;
-  }
-
-  // Initialize the register pressure tracker used by buildSchedGraph.
-  RPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd,
-                 ShouldTrackLaneMasks, /*TrackUntiedDefs=*/true);
-
-  // Account for liveness generate by the region boundary.
-  if (LiveRegionEnd != RegionEnd)
-    RPTracker.recede();
-
-  // Build the DAG, and compute current register pressure.
-  buildSchedGraph(AA, &RPTracker, &SUPressureDiffs, LIS, ShouldTrackLaneMasks);
-
-  // Initialize top/bottom trackers after computing region pressure.
-  initRegPressure();
-}
-
-void ScheduleDAGMILive::computeDFSResult() {
-  if (!DFSResult)
-    DFSResult = new SchedDFSResult(/*BottomU*/true, MinSubtreeSize);
-  DFSResult->clear();
-  ScheduledTrees.clear();
-  DFSResult->resize(SUnits.size());
-  DFSResult->compute(SUnits);
-  ScheduledTrees.resize(DFSResult->getNumSubtrees());
-}
-
-/// Compute the max cyclic critical path through the DAG. The scheduling DAG
-/// only provides the critical path for single block loops. To handle loops that
-/// span blocks, we could use the vreg path latencies provided by
-/// MachineTraceMetrics instead. However, MachineTraceMetrics is not currently
-/// available for use in the scheduler.
-///
-/// The cyclic path estimation identifies a def-use pair that crosses the back
-/// edge and considers the depth and height of the nodes. For example, consider
-/// the following instruction sequence where each instruction has unit latency
+    /// FIXME: Currently assuming single-use physregs. 
+    if (!Register::isVirtualRegister(Reg)) 
+      continue; 
+ 
+    if (ShouldTrackLaneMasks) { 
+      // If the register has just become live then other uses won't change 
+      // this fact anymore => decrement pressure. 
+      // If the register has just become dead then other uses make it come 
+      // back to life => increment pressure. 
+      bool Decrement = P.LaneMask.any(); 
+ 
+      for (const VReg2SUnit &V2SU 
+           : make_range(VRegUses.find(Reg), VRegUses.end())) { 
+        SUnit &SU = *V2SU.SU; 
+        if (SU.isScheduled || &SU == &ExitSU) 
+          continue; 
+ 
+        PressureDiff &PDiff = getPressureDiff(&SU); 
+        PDiff.addPressureChange(Reg, Decrement, &MRI); 
+        LLVM_DEBUG(dbgs() << "  UpdateRegP: SU(" << SU.NodeNum << ") " 
+                          << printReg(Reg, TRI) << ':' 
+                          << PrintLaneMask(P.LaneMask) << ' ' << *SU.getInstr(); 
+                   dbgs() << "              to "; PDiff.dump(*TRI);); 
+      } 
+    } else { 
+      assert(P.LaneMask.any()); 
+      LLVM_DEBUG(dbgs() << "  LiveReg: " << printVRegOrUnit(Reg, TRI) << "\n"); 
+      // This may be called before CurrentBottom has been initialized. However, 
+      // BotRPTracker must have a valid position. We want the value live into the 
+      // instruction or live out of the block, so ask for the previous 
+      // instruction's live-out. 
+      const LiveInterval &LI = LIS->getInterval(Reg); 
+      VNInfo *VNI; 
+      MachineBasicBlock::const_iterator I = 
+        nextIfDebug(BotRPTracker.getPos(), BB->end()); 
+      if (I == BB->end()) 
+        VNI = LI.getVNInfoBefore(LIS->getMBBEndIdx(BB)); 
+      else { 
+        LiveQueryResult LRQ = LI.Query(LIS->getInstructionIndex(*I)); 
+        VNI = LRQ.valueIn(); 
+      } 
+      // RegisterPressureTracker guarantees that readsReg is true for LiveUses. 
+      assert(VNI && "No live value at use."); 
+      for (const VReg2SUnit &V2SU 
+           : make_range(VRegUses.find(Reg), VRegUses.end())) { 
+        SUnit *SU = V2SU.SU; 
+        // If this use comes before the reaching def, it cannot be a last use, 
+        // so decrease its pressure change. 
+        if (!SU->isScheduled && SU != &ExitSU) { 
+          LiveQueryResult LRQ = 
+              LI.Query(LIS->getInstructionIndex(*SU->getInstr())); 
+          if (LRQ.valueIn() == VNI) { 
+            PressureDiff &PDiff = getPressureDiff(SU); 
+            PDiff.addPressureChange(Reg, true, &MRI); 
+            LLVM_DEBUG(dbgs() << "  UpdateRegP: SU(" << SU->NodeNum << ") " 
+                              << *SU->getInstr(); 
+                       dbgs() << "              to "; PDiff.dump(*TRI);); 
+          } 
+        } 
+      } 
+    } 
+  } 
+} 
+ 
+void ScheduleDAGMILive::dump() const { 
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 
+  if (EntrySU.getInstr() != nullptr) 
+    dumpNodeAll(EntrySU); 
+  for (const SUnit &SU : SUnits) { 
+    dumpNodeAll(SU); 
+    if (ShouldTrackPressure) { 
+      dbgs() << "  Pressure Diff      : "; 
+      getPressureDiff(&SU).dump(*TRI); 
+    } 
+    dbgs() << "  Single Issue       : "; 
+    if (SchedModel.mustBeginGroup(SU.getInstr()) && 
+        SchedModel.mustEndGroup(SU.getInstr())) 
+      dbgs() << "true;"; 
+    else 
+      dbgs() << "false;"; 
+    dbgs() << '\n'; 
+  } 
+  if (ExitSU.getInstr() != nullptr) 
+    dumpNodeAll(ExitSU); 
+#endif 
+} 
+ 
+/// schedule - Called back from MachineScheduler::runOnMachineFunction 
+/// after setting up the current scheduling region. [RegionBegin, RegionEnd) 
+/// only includes instructions that have DAG nodes, not scheduling boundaries. 
+/// 
+/// This is a skeletal driver, with all the functionality pushed into helpers, 
+/// so that it can be easily extended by experimental schedulers. Generally, 
+/// implementing MachineSchedStrategy should be sufficient to implement a new 
+/// scheduling algorithm. However, if a scheduler further subclasses 
+/// ScheduleDAGMILive then it will want to override this virtual method in order 
+/// to update any specialized state. 
+void ScheduleDAGMILive::schedule() { 
+  LLVM_DEBUG(dbgs() << "ScheduleDAGMILive::schedule starting\n"); 
+  LLVM_DEBUG(SchedImpl->dumpPolicy()); 
+  buildDAGWithRegPressure(); 
+ 
+  postprocessDAG(); 
+ 
+  SmallVector<SUnit*, 8> TopRoots, BotRoots; 
+  findRootsAndBiasEdges(TopRoots, BotRoots); 
+ 
+  // Initialize the strategy before modifying the DAG. 
+  // This may initialize a DFSResult to be used for queue priority. 
+  SchedImpl->initialize(this); 
+ 
+  LLVM_DEBUG(dump()); 
+  if (PrintDAGs) dump(); 
+  if (ViewMISchedDAGs) viewGraph(); 
+ 
+  // Initialize ready queues now that the DAG and priority data are finalized. 
+  initQueues(TopRoots, BotRoots); 
+ 
+  bool IsTopNode = false; 
+  while (true) { 
+    LLVM_DEBUG(dbgs() << "** ScheduleDAGMILive::schedule picking next node\n"); 
+    SUnit *SU = SchedImpl->pickNode(IsTopNode); 
+    if (!SU) break; 
+ 
+    assert(!SU->isScheduled && "Node already scheduled"); 
+    if (!checkSchedLimit()) 
+      break; 
+ 
+    scheduleMI(SU, IsTopNode); 
+ 
+    if (DFSResult) { 
+      unsigned SubtreeID = DFSResult->getSubtreeID(SU); 
+      if (!ScheduledTrees.test(SubtreeID)) { 
+        ScheduledTrees.set(SubtreeID); 
+        DFSResult->scheduleTree(SubtreeID); 
+        SchedImpl->scheduleTree(SubtreeID); 
+      } 
+    } 
+ 
+    // Notify the scheduling strategy after updating the DAG. 
+    SchedImpl->schedNode(SU, IsTopNode); 
+ 
+    updateQueues(SU, IsTopNode); 
+  } 
+  assert(CurrentTop == CurrentBottom && "Nonempty unscheduled zone."); 
+ 
+  placeDebugValues(); 
+ 
+  LLVM_DEBUG({ 
+    dbgs() << "*** Final schedule for " 
+           << printMBBReference(*begin()->getParent()) << " ***\n"; 
+    dumpSchedule(); 
+    dbgs() << '\n'; 
+  }); 
+} 
+ 
+/// Build the DAG and setup three register pressure trackers. 
+void ScheduleDAGMILive::buildDAGWithRegPressure() { 
+  if (!ShouldTrackPressure) { 
+    RPTracker.reset(); 
+    RegionCriticalPSets.clear(); 
+    buildSchedGraph(AA); 
+    return; 
+  } 
+ 
+  // Initialize the register pressure tracker used by buildSchedGraph. 
+  RPTracker.init(&MF, RegClassInfo, LIS, BB, LiveRegionEnd, 
+                 ShouldTrackLaneMasks, /*TrackUntiedDefs=*/true); 
+ 
+  // Account for liveness generate by the region boundary. 
+  if (LiveRegionEnd != RegionEnd) 
+    RPTracker.recede(); 
+ 
+  // Build the DAG, and compute current register pressure. 
+  buildSchedGraph(AA, &RPTracker, &SUPressureDiffs, LIS, ShouldTrackLaneMasks); 
+ 
+  // Initialize top/bottom trackers after computing region pressure. 
+  initRegPressure(); 
+} 
+ 
+void ScheduleDAGMILive::computeDFSResult() { 
+  if (!DFSResult) 
+    DFSResult = new SchedDFSResult(/*BottomU*/true, MinSubtreeSize); 
+  DFSResult->clear(); 
+  ScheduledTrees.clear(); 
+  DFSResult->resize(SUnits.size()); 
+  DFSResult->compute(SUnits); 
+  ScheduledTrees.resize(DFSResult->getNumSubtrees()); 
+} 
+ 
+/// Compute the max cyclic critical path through the DAG. The scheduling DAG 
+/// only provides the critical path for single block loops. To handle loops that 
+/// span blocks, we could use the vreg path latencies provided by 
+/// MachineTraceMetrics instead. However, MachineTraceMetrics is not currently 
+/// available for use in the scheduler. 
+/// 
+/// The cyclic path estimation identifies a def-use pair that crosses the back 
+/// edge and considers the depth and height of the nodes. For example, consider 
+/// the following instruction sequence where each instruction has unit latency 
 /// and defines an eponymous virtual register:
-///
-/// a->b(a,c)->c(b)->d(c)->exit
-///
-/// The cyclic critical path is a two cycles: b->c->b
-/// The acyclic critical path is four cycles: a->b->c->d->exit
-/// LiveOutHeight = height(c) = len(c->d->exit) = 2
-/// LiveOutDepth = depth(c) + 1 = len(a->b->c) + 1 = 3
-/// LiveInHeight = height(b) + 1 = len(b->c->d->exit) + 1 = 4
-/// LiveInDepth = depth(b) = len(a->b) = 1
-///
-/// LiveOutDepth - LiveInDepth = 3 - 1 = 2
-/// LiveInHeight - LiveOutHeight = 4 - 2 = 2
-/// CyclicCriticalPath = min(2, 2) = 2
-///
-/// This could be relevant to PostRA scheduling, but is currently implemented
-/// assuming LiveIntervals.
-unsigned ScheduleDAGMILive::computeCyclicCriticalPath() {
-  // This only applies to single block loop.
-  if (!BB->isSuccessor(BB))
-    return 0;
-
-  unsigned MaxCyclicLatency = 0;
-  // Visit each live out vreg def to find def/use pairs that cross iterations.
-  for (const RegisterMaskPair &P : RPTracker.getPressure().LiveOutRegs) {
+/// 
+/// a->b(a,c)->c(b)->d(c)->exit 
+/// 
+/// The cyclic critical path is a two cycles: b->c->b 
+/// The acyclic critical path is four cycles: a->b->c->d->exit 
+/// LiveOutHeight = height(c) = len(c->d->exit) = 2 
+/// LiveOutDepth = depth(c) + 1 = len(a->b->c) + 1 = 3 
+/// LiveInHeight = height(b) + 1 = len(b->c->d->exit) + 1 = 4 
+/// LiveInDepth = depth(b) = len(a->b) = 1 
+/// 
+/// LiveOutDepth - LiveInDepth = 3 - 1 = 2 
+/// LiveInHeight - LiveOutHeight = 4 - 2 = 2 
+/// CyclicCriticalPath = min(2, 2) = 2 
+/// 
+/// This could be relevant to PostRA scheduling, but is currently implemented 
+/// assuming LiveIntervals. 
+unsigned ScheduleDAGMILive::computeCyclicCriticalPath() { 
+  // This only applies to single block loop. 
+  if (!BB->isSuccessor(BB)) 
+    return 0; 
+ 
+  unsigned MaxCyclicLatency = 0; 
+  // Visit each live out vreg def to find def/use pairs that cross iterations. 
+  for (const RegisterMaskPair &P : RPTracker.getPressure().LiveOutRegs) { 
     Register Reg = P.RegUnit;
-    if (!Register::isVirtualRegister(Reg))
-      continue;
-    const LiveInterval &LI = LIS->getInterval(Reg);
-    const VNInfo *DefVNI = LI.getVNInfoBefore(LIS->getMBBEndIdx(BB));
-    if (!DefVNI)
-      continue;
-
-    MachineInstr *DefMI = LIS->getInstructionFromIndex(DefVNI->def);
-    const SUnit *DefSU = getSUnit(DefMI);
-    if (!DefSU)
-      continue;
-
-    unsigned LiveOutHeight = DefSU->getHeight();
-    unsigned LiveOutDepth = DefSU->getDepth() + DefSU->Latency;
-    // Visit all local users of the vreg def.
-    for (const VReg2SUnit &V2SU
-         : make_range(VRegUses.find(Reg), VRegUses.end())) {
-      SUnit *SU = V2SU.SU;
-      if (SU == &ExitSU)
-        continue;
-
-      // Only consider uses of the phi.
-      LiveQueryResult LRQ = LI.Query(LIS->getInstructionIndex(*SU->getInstr()));
-      if (!LRQ.valueIn()->isPHIDef())
-        continue;
-
-      // Assume that a path spanning two iterations is a cycle, which could
-      // overestimate in strange cases. This allows cyclic latency to be
-      // estimated as the minimum slack of the vreg's depth or height.
-      unsigned CyclicLatency = 0;
-      if (LiveOutDepth > SU->getDepth())
-        CyclicLatency = LiveOutDepth - SU->getDepth();
-
-      unsigned LiveInHeight = SU->getHeight() + DefSU->Latency;
-      if (LiveInHeight > LiveOutHeight) {
-        if (LiveInHeight - LiveOutHeight < CyclicLatency)
-          CyclicLatency = LiveInHeight - LiveOutHeight;
-      } else
-        CyclicLatency = 0;
-
-      LLVM_DEBUG(dbgs() << "Cyclic Path: SU(" << DefSU->NodeNum << ") -> SU("
-                        << SU->NodeNum << ") = " << CyclicLatency << "c\n");
-      if (CyclicLatency > MaxCyclicLatency)
-        MaxCyclicLatency = CyclicLatency;
-    }
-  }
-  LLVM_DEBUG(dbgs() << "Cyclic Critical Path: " << MaxCyclicLatency << "c\n");
-  return MaxCyclicLatency;
-}
-
-/// Release ExitSU predecessors and setup scheduler queues. Re-position
-/// the Top RP tracker in case the region beginning has changed.
-void ScheduleDAGMILive::initQueues(ArrayRef<SUnit*> TopRoots,
-                                   ArrayRef<SUnit*> BotRoots) {
-  ScheduleDAGMI::initQueues(TopRoots, BotRoots);
-  if (ShouldTrackPressure) {
-    assert(TopRPTracker.getPos() == RegionBegin && "bad initial Top tracker");
-    TopRPTracker.setPos(CurrentTop);
-  }
-}
-
-/// Move an instruction and update register pressure.
-void ScheduleDAGMILive::scheduleMI(SUnit *SU, bool IsTopNode) {
-  // Move the instruction to its new location in the instruction stream.
-  MachineInstr *MI = SU->getInstr();
-
-  if (IsTopNode) {
-    assert(SU->isTopReady() && "node still has unscheduled dependencies");
-    if (&*CurrentTop == MI)
-      CurrentTop = nextIfDebug(++CurrentTop, CurrentBottom);
-    else {
-      moveInstruction(MI, CurrentTop);
-      TopRPTracker.setPos(MI);
-    }
-
-    if (ShouldTrackPressure) {
-      // Update top scheduled pressure.
-      RegisterOperands RegOpers;
-      RegOpers.collect(*MI, *TRI, MRI, ShouldTrackLaneMasks, false);
-      if (ShouldTrackLaneMasks) {
-        // Adjust liveness and add missing dead+read-undef flags.
-        SlotIndex SlotIdx = LIS->getInstructionIndex(*MI).getRegSlot();
-        RegOpers.adjustLaneLiveness(*LIS, MRI, SlotIdx, MI);
-      } else {
-        // Adjust for missing dead-def flags.
-        RegOpers.detectDeadDefs(*MI, *LIS);
-      }
-
-      TopRPTracker.advance(RegOpers);
-      assert(TopRPTracker.getPos() == CurrentTop && "out of sync");
-      LLVM_DEBUG(dbgs() << "Top Pressure:\n"; dumpRegSetPressure(
-                     TopRPTracker.getRegSetPressureAtPos(), TRI););
-
-      updateScheduledPressure(SU, TopRPTracker.getPressure().MaxSetPressure);
-    }
-  } else {
-    assert(SU->isBottomReady() && "node still has unscheduled dependencies");
-    MachineBasicBlock::iterator priorII =
-      priorNonDebug(CurrentBottom, CurrentTop);
-    if (&*priorII == MI)
-      CurrentBottom = priorII;
-    else {
-      if (&*CurrentTop == MI) {
-        CurrentTop = nextIfDebug(++CurrentTop, priorII);
-        TopRPTracker.setPos(CurrentTop);
-      }
-      moveInstruction(MI, CurrentBottom);
-      CurrentBottom = MI;
-      BotRPTracker.setPos(CurrentBottom);
-    }
-    if (ShouldTrackPressure) {
-      RegisterOperands RegOpers;
-      RegOpers.collect(*MI, *TRI, MRI, ShouldTrackLaneMasks, false);
-      if (ShouldTrackLaneMasks) {
-        // Adjust liveness and add missing dead+read-undef flags.
-        SlotIndex SlotIdx = LIS->getInstructionIndex(*MI).getRegSlot();
-        RegOpers.adjustLaneLiveness(*LIS, MRI, SlotIdx, MI);
-      } else {
-        // Adjust for missing dead-def flags.
-        RegOpers.detectDeadDefs(*MI, *LIS);
-      }
-
-      if (BotRPTracker.getPos() != CurrentBottom)
-        BotRPTracker.recedeSkipDebugValues();
-      SmallVector<RegisterMaskPair, 8> LiveUses;
-      BotRPTracker.recede(RegOpers, &LiveUses);
-      assert(BotRPTracker.getPos() == CurrentBottom && "out of sync");
-      LLVM_DEBUG(dbgs() << "Bottom Pressure:\n"; dumpRegSetPressure(
-                     BotRPTracker.getRegSetPressureAtPos(), TRI););
-
-      updateScheduledPressure(SU, BotRPTracker.getPressure().MaxSetPressure);
-      updatePressureDiffs(LiveUses);
-    }
-  }
-}
-
-//===----------------------------------------------------------------------===//
-// BaseMemOpClusterMutation - DAG post-processing to cluster loads or stores.
-//===----------------------------------------------------------------------===//
-
-namespace {
-
-/// Post-process the DAG to create cluster edges between neighboring
-/// loads or between neighboring stores.
-class BaseMemOpClusterMutation : public ScheduleDAGMutation {
-  struct MemOpInfo {
-    SUnit *SU;
-    SmallVector<const MachineOperand *, 4> BaseOps;
-    int64_t Offset;
-    unsigned Width;
-
-    MemOpInfo(SUnit *SU, ArrayRef<const MachineOperand *> BaseOps,
-              int64_t Offset, unsigned Width)
-        : SU(SU), BaseOps(BaseOps.begin(), BaseOps.end()), Offset(Offset),
-          Width(Width) {}
-
-    static bool Compare(const MachineOperand *const &A,
-                        const MachineOperand *const &B) {
-      if (A->getType() != B->getType())
-        return A->getType() < B->getType();
-      if (A->isReg())
-        return A->getReg() < B->getReg();
-      if (A->isFI()) {
-        const MachineFunction &MF = *A->getParent()->getParent()->getParent();
-        const TargetFrameLowering &TFI = *MF.getSubtarget().getFrameLowering();
-        bool StackGrowsDown = TFI.getStackGrowthDirection() ==
-                              TargetFrameLowering::StackGrowsDown;
-        return StackGrowsDown ? A->getIndex() > B->getIndex()
-                              : A->getIndex() < B->getIndex();
-      }
-
-      llvm_unreachable("MemOpClusterMutation only supports register or frame "
-                       "index bases.");
-    }
-
-    bool operator<(const MemOpInfo &RHS) const {
-      // FIXME: Don't compare everything twice. Maybe use C++20 three way
-      // comparison instead when it's available.
-      if (std::lexicographical_compare(BaseOps.begin(), BaseOps.end(),
-                                       RHS.BaseOps.begin(), RHS.BaseOps.end(),
-                                       Compare))
-        return true;
-      if (std::lexicographical_compare(RHS.BaseOps.begin(), RHS.BaseOps.end(),
-                                       BaseOps.begin(), BaseOps.end(), Compare))
-        return false;
-      if (Offset != RHS.Offset)
-        return Offset < RHS.Offset;
-      return SU->NodeNum < RHS.SU->NodeNum;
-    }
-  };
-
-  const TargetInstrInfo *TII;
-  const TargetRegisterInfo *TRI;
-  bool IsLoad;
-
-public:
-  BaseMemOpClusterMutation(const TargetInstrInfo *tii,
-                           const TargetRegisterInfo *tri, bool IsLoad)
-      : TII(tii), TRI(tri), IsLoad(IsLoad) {}
-
-  void apply(ScheduleDAGInstrs *DAGInstrs) override;
-
-protected:
+    if (!Register::isVirtualRegister(Reg)) 
+      continue; 
+    const LiveInterval &LI = LIS->getInterval(Reg); 
+    const VNInfo *DefVNI = LI.getVNInfoBefore(LIS->getMBBEndIdx(BB)); 
+    if (!DefVNI) 
+      continue; 
+ 
+    MachineInstr *DefMI = LIS->getInstructionFromIndex(DefVNI->def); 
+    const SUnit *DefSU = getSUnit(DefMI); 
+    if (!DefSU) 
+      continue; 
+ 
+    unsigned LiveOutHeight = DefSU->getHeight(); 
+    unsigned LiveOutDepth = DefSU->getDepth() + DefSU->Latency; 
+    // Visit all local users of the vreg def. 
+    for (const VReg2SUnit &V2SU 
+         : make_range(VRegUses.find(Reg), VRegUses.end())) { 
+      SUnit *SU = V2SU.SU; 
+      if (SU == &ExitSU) 
+        continue; 
+ 
+      // Only consider uses of the phi. 
+      LiveQueryResult LRQ = LI.Query(LIS->getInstructionIndex(*SU->getInstr())); 
+      if (!LRQ.valueIn()->isPHIDef()) 
+        continue; 
+ 
+      // Assume that a path spanning two iterations is a cycle, which could 
+      // overestimate in strange cases. This allows cyclic latency to be 
+      // estimated as the minimum slack of the vreg's depth or height. 
+      unsigned CyclicLatency = 0; 
+      if (LiveOutDepth > SU->getDepth()) 
+        CyclicLatency = LiveOutDepth - SU->getDepth(); 
+ 
+      unsigned LiveInHeight = SU->getHeight() + DefSU->Latency; 
+      if (LiveInHeight > LiveOutHeight) { 
+        if (LiveInHeight - LiveOutHeight < CyclicLatency) 
+          CyclicLatency = LiveInHeight - LiveOutHeight; 
+      } else 
+        CyclicLatency = 0; 
+ 
+      LLVM_DEBUG(dbgs() << "Cyclic Path: SU(" << DefSU->NodeNum << ") -> SU(" 
+                        << SU->NodeNum << ") = " << CyclicLatency << "c\n"); 
+      if (CyclicLatency > MaxCyclicLatency) 
+        MaxCyclicLatency = CyclicLatency; 
+    } 
+  } 
+  LLVM_DEBUG(dbgs() << "Cyclic Critical Path: " << MaxCyclicLatency << "c\n"); 
+  return MaxCyclicLatency; 
+} 
+ 
+/// Release ExitSU predecessors and setup scheduler queues. Re-position 
+/// the Top RP tracker in case the region beginning has changed. 
+void ScheduleDAGMILive::initQueues(ArrayRef<SUnit*> TopRoots, 
+                                   ArrayRef<SUnit*> BotRoots) { 
+  ScheduleDAGMI::initQueues(TopRoots, BotRoots); 
+  if (ShouldTrackPressure) { 
+    assert(TopRPTracker.getPos() == RegionBegin && "bad initial Top tracker"); 
+    TopRPTracker.setPos(CurrentTop); 
+  } 
+} 
+ 
+/// Move an instruction and update register pressure. 
+void ScheduleDAGMILive::scheduleMI(SUnit *SU, bool IsTopNode) { 
+  // Move the instruction to its new location in the instruction stream. 
+  MachineInstr *MI = SU->getInstr(); 
+ 
+  if (IsTopNode) { 
+    assert(SU->isTopReady() && "node still has unscheduled dependencies"); 
+    if (&*CurrentTop == MI) 
+      CurrentTop = nextIfDebug(++CurrentTop, CurrentBottom); 
+    else { 
+      moveInstruction(MI, CurrentTop); 
+      TopRPTracker.setPos(MI); 
+    } 
+ 
+    if (ShouldTrackPressure) { 
+      // Update top scheduled pressure. 
+      RegisterOperands RegOpers; 
+      RegOpers.collect(*MI, *TRI, MRI, ShouldTrackLaneMasks, false); 
+      if (ShouldTrackLaneMasks) { 
+        // Adjust liveness and add missing dead+read-undef flags. 
+        SlotIndex SlotIdx = LIS->getInstructionIndex(*MI).getRegSlot(); 
+        RegOpers.adjustLaneLiveness(*LIS, MRI, SlotIdx, MI); 
+      } else { 
+        // Adjust for missing dead-def flags. 
+        RegOpers.detectDeadDefs(*MI, *LIS); 
+      } 
+ 
+      TopRPTracker.advance(RegOpers); 
+      assert(TopRPTracker.getPos() == CurrentTop && "out of sync"); 
+      LLVM_DEBUG(dbgs() << "Top Pressure:\n"; dumpRegSetPressure( 
+                     TopRPTracker.getRegSetPressureAtPos(), TRI);); 
+ 
+      updateScheduledPressure(SU, TopRPTracker.getPressure().MaxSetPressure); 
+    } 
+  } else { 
+    assert(SU->isBottomReady() && "node still has unscheduled dependencies"); 
+    MachineBasicBlock::iterator priorII = 
+      priorNonDebug(CurrentBottom, CurrentTop); 
+    if (&*priorII == MI) 
+      CurrentBottom = priorII; 
+    else { 
+      if (&*CurrentTop == MI) { 
+        CurrentTop = nextIfDebug(++CurrentTop, priorII); 
+        TopRPTracker.setPos(CurrentTop); 
+      } 
+      moveInstruction(MI, CurrentBottom); 
+      CurrentBottom = MI; 
+      BotRPTracker.setPos(CurrentBottom); 
+    } 
+    if (ShouldTrackPressure) { 
+      RegisterOperands RegOpers; 
+      RegOpers.collect(*MI, *TRI, MRI, ShouldTrackLaneMasks, false); 
+      if (ShouldTrackLaneMasks) { 
+        // Adjust liveness and add missing dead+read-undef flags. 
+        SlotIndex SlotIdx = LIS->getInstructionIndex(*MI).getRegSlot(); 
+        RegOpers.adjustLaneLiveness(*LIS, MRI, SlotIdx, MI); 
+      } else { 
+        // Adjust for missing dead-def flags. 
+        RegOpers.detectDeadDefs(*MI, *LIS); 
+      } 
+ 
+      if (BotRPTracker.getPos() != CurrentBottom) 
+        BotRPTracker.recedeSkipDebugValues(); 
+      SmallVector<RegisterMaskPair, 8> LiveUses; 
+      BotRPTracker.recede(RegOpers, &LiveUses); 
+      assert(BotRPTracker.getPos() == CurrentBottom && "out of sync"); 
+      LLVM_DEBUG(dbgs() << "Bottom Pressure:\n"; dumpRegSetPressure( 
+                     BotRPTracker.getRegSetPressureAtPos(), TRI);); 
+ 
+      updateScheduledPressure(SU, BotRPTracker.getPressure().MaxSetPressure); 
+      updatePressureDiffs(LiveUses); 
+    } 
+  } 
+} 
+ 
+//===----------------------------------------------------------------------===// 
+// BaseMemOpClusterMutation - DAG post-processing to cluster loads or stores. 
+//===----------------------------------------------------------------------===// 
+ 
+namespace { 
+ 
+/// Post-process the DAG to create cluster edges between neighboring 
+/// loads or between neighboring stores. 
+class BaseMemOpClusterMutation : public ScheduleDAGMutation { 
+  struct MemOpInfo { 
+    SUnit *SU; 
+    SmallVector<const MachineOperand *, 4> BaseOps; 
+    int64_t Offset; 
+    unsigned Width; 
+ 
+    MemOpInfo(SUnit *SU, ArrayRef<const MachineOperand *> BaseOps, 
+              int64_t Offset, unsigned Width) 
+        : SU(SU), BaseOps(BaseOps.begin(), BaseOps.end()), Offset(Offset), 
+          Width(Width) {} 
+ 
+    static bool Compare(const MachineOperand *const &A, 
+                        const MachineOperand *const &B) { 
+      if (A->getType() != B->getType()) 
+        return A->getType() < B->getType(); 
+      if (A->isReg()) 
+        return A->getReg() < B->getReg(); 
+      if (A->isFI()) { 
+        const MachineFunction &MF = *A->getParent()->getParent()->getParent(); 
+        const TargetFrameLowering &TFI = *MF.getSubtarget().getFrameLowering(); 
+        bool StackGrowsDown = TFI.getStackGrowthDirection() == 
+                              TargetFrameLowering::StackGrowsDown; 
+        return StackGrowsDown ? A->getIndex() > B->getIndex() 
+                              : A->getIndex() < B->getIndex(); 
+      } 
+ 
+      llvm_unreachable("MemOpClusterMutation only supports register or frame " 
+                       "index bases."); 
+    } 
+ 
+    bool operator<(const MemOpInfo &RHS) const { 
+      // FIXME: Don't compare everything twice. Maybe use C++20 three way 
+      // comparison instead when it's available. 
+      if (std::lexicographical_compare(BaseOps.begin(), BaseOps.end(), 
+                                       RHS.BaseOps.begin(), RHS.BaseOps.end(), 
+                                       Compare)) 
+        return true; 
+      if (std::lexicographical_compare(RHS.BaseOps.begin(), RHS.BaseOps.end(), 
+                                       BaseOps.begin(), BaseOps.end(), Compare)) 
+        return false; 
+      if (Offset != RHS.Offset) 
+        return Offset < RHS.Offset; 
+      return SU->NodeNum < RHS.SU->NodeNum; 
+    } 
+  }; 
+ 
+  const TargetInstrInfo *TII; 
+  const TargetRegisterInfo *TRI; 
+  bool IsLoad; 
+ 
+public: 
+  BaseMemOpClusterMutation(const TargetInstrInfo *tii, 
+                           const TargetRegisterInfo *tri, bool IsLoad) 
+      : TII(tii), TRI(tri), IsLoad(IsLoad) {} 
+ 
+  void apply(ScheduleDAGInstrs *DAGInstrs) override; 
+ 
+protected: 
   void clusterNeighboringMemOps(ArrayRef<MemOpInfo> MemOps, bool FastCluster,
                                 ScheduleDAGInstrs *DAG);
   void collectMemOpRecords(std::vector<SUnit> &SUnits,
                            SmallVectorImpl<MemOpInfo> &MemOpRecords);
   bool groupMemOps(ArrayRef<MemOpInfo> MemOps, ScheduleDAGInstrs *DAG,
                    DenseMap<unsigned, SmallVector<MemOpInfo, 32>> &Groups);
-};
-
-class StoreClusterMutation : public BaseMemOpClusterMutation {
-public:
-  StoreClusterMutation(const TargetInstrInfo *tii,
-                       const TargetRegisterInfo *tri)
-      : BaseMemOpClusterMutation(tii, tri, false) {}
-};
-
-class LoadClusterMutation : public BaseMemOpClusterMutation {
-public:
-  LoadClusterMutation(const TargetInstrInfo *tii, const TargetRegisterInfo *tri)
-      : BaseMemOpClusterMutation(tii, tri, true) {}
-};
-
-} // end anonymous namespace
-
-namespace llvm {
-
-std::unique_ptr<ScheduleDAGMutation>
-createLoadClusterDAGMutation(const TargetInstrInfo *TII,
-                             const TargetRegisterInfo *TRI) {
-  return EnableMemOpCluster ? std::make_unique<LoadClusterMutation>(TII, TRI)
-                            : nullptr;
-}
-
-std::unique_ptr<ScheduleDAGMutation>
-createStoreClusterDAGMutation(const TargetInstrInfo *TII,
-                              const TargetRegisterInfo *TRI) {
-  return EnableMemOpCluster ? std::make_unique<StoreClusterMutation>(TII, TRI)
-                            : nullptr;
-}
-
-} // end namespace llvm
-
+}; 
+ 
+class StoreClusterMutation : public BaseMemOpClusterMutation { 
+public: 
+  StoreClusterMutation(const TargetInstrInfo *tii, 
+                       const TargetRegisterInfo *tri) 
+      : BaseMemOpClusterMutation(tii, tri, false) {} 
+}; 
+ 
+class LoadClusterMutation : public BaseMemOpClusterMutation { 
+public: 
+  LoadClusterMutation(const TargetInstrInfo *tii, const TargetRegisterInfo *tri) 
+      : BaseMemOpClusterMutation(tii, tri, true) {} 
+}; 
+ 
+} // end anonymous namespace 
+ 
+namespace llvm { 
+ 
+std::unique_ptr<ScheduleDAGMutation> 
+createLoadClusterDAGMutation(const TargetInstrInfo *TII, 
+                             const TargetRegisterInfo *TRI) { 
+  return EnableMemOpCluster ? std::make_unique<LoadClusterMutation>(TII, TRI) 
+                            : nullptr; 
+} 
+ 
+std::unique_ptr<ScheduleDAGMutation> 
+createStoreClusterDAGMutation(const TargetInstrInfo *TII, 
+                              const TargetRegisterInfo *TRI) { 
+  return EnableMemOpCluster ? std::make_unique<StoreClusterMutation>(TII, TRI) 
+                            : nullptr; 
+} 
+ 
+} // end namespace llvm 
+ 
 // Sorting all the loads/stores first, then for each load/store, checking the
 // following load/store one by one, until reach the first non-dependent one and
 // call target hook to see if they can cluster.
 // If FastCluster is enabled, we assume that, all the loads/stores have been
 // preprocessed and now, they didn't have dependencies on each other.
-void BaseMemOpClusterMutation::clusterNeighboringMemOps(
+void BaseMemOpClusterMutation::clusterNeighboringMemOps( 
     ArrayRef<MemOpInfo> MemOpRecords, bool FastCluster,
     ScheduleDAGInstrs *DAG) {
   // Keep track of the current cluster length and bytes for each SUnit.
   DenseMap<unsigned, std::pair<unsigned, unsigned>> SUnit2ClusterInfo;
-
-  // At this point, `MemOpRecords` array must hold atleast two mem ops. Try to
-  // cluster mem ops collected within `MemOpRecords` array.
-  for (unsigned Idx = 0, End = MemOpRecords.size(); Idx < (End - 1); ++Idx) {
-    // Decision to cluster mem ops is taken based on target dependent logic
-    auto MemOpa = MemOpRecords[Idx];
+ 
+  // At this point, `MemOpRecords` array must hold atleast two mem ops. Try to 
+  // cluster mem ops collected within `MemOpRecords` array. 
+  for (unsigned Idx = 0, End = MemOpRecords.size(); Idx < (End - 1); ++Idx) { 
+    // Decision to cluster mem ops is taken based on target dependent logic 
+    auto MemOpa = MemOpRecords[Idx]; 
 
     // Seek for the next load/store to do the cluster.
     unsigned NextIdx = Idx + 1;
@@ -1613,7 +1613,7 @@ void BaseMemOpClusterMutation::clusterNeighboringMemOps(
             !DAG->IsReachable(MemOpa.SU, MemOpRecords[NextIdx].SU))))
         break;
     if (NextIdx == End)
-      continue;
+      continue; 
 
     auto MemOpb = MemOpRecords[NextIdx];
     unsigned ClusterLength = 2;
@@ -1622,25 +1622,25 @@ void BaseMemOpClusterMutation::clusterNeighboringMemOps(
       ClusterLength = SUnit2ClusterInfo[MemOpa.SU->NodeNum].first + 1;
       CurrentClusterBytes =
           SUnit2ClusterInfo[MemOpa.SU->NodeNum].second + MemOpb.Width;
-    }
-
+    } 
+ 
     if (!TII->shouldClusterMemOps(MemOpa.BaseOps, MemOpb.BaseOps, ClusterLength,
                                   CurrentClusterBytes))
       continue;
 
-    SUnit *SUa = MemOpa.SU;
-    SUnit *SUb = MemOpb.SU;
-    if (SUa->NodeNum > SUb->NodeNum)
-      std::swap(SUa, SUb);
-
-    // FIXME: Is this check really required?
+    SUnit *SUa = MemOpa.SU; 
+    SUnit *SUb = MemOpb.SU; 
+    if (SUa->NodeNum > SUb->NodeNum) 
+      std::swap(SUa, SUb); 
+ 
+    // FIXME: Is this check really required? 
     if (!DAG->addEdge(SUb, SDep(SUa, SDep::Cluster)))
-      continue;
-
-    LLVM_DEBUG(dbgs() << "Cluster ld/st SU(" << SUa->NodeNum << ") - SU("
-                      << SUb->NodeNum << ")\n");
+      continue; 
+ 
+    LLVM_DEBUG(dbgs() << "Cluster ld/st SU(" << SUa->NodeNum << ") - SU(" 
+                      << SUb->NodeNum << ")\n"); 
     ++NumClustered;
-
+ 
     if (IsLoad) {
       // Copy successor edges from SUa to SUb. Interleaving computation
       // dependent on SUa can prevent load combining due to register reuse.
@@ -1667,24 +1667,24 @@ void BaseMemOpClusterMutation::clusterNeighboringMemOps(
                           << ")\n");
         DAG->addEdge(SUa, SDep(Pred.getSUnit(), SDep::Artificial));
       }
-    }
-
+    } 
+ 
     SUnit2ClusterInfo[MemOpb.SU->NodeNum] = {ClusterLength,
                                              CurrentClusterBytes};
 
-    LLVM_DEBUG(dbgs() << "  Curr cluster length: " << ClusterLength
-                      << ", Curr cluster bytes: " << CurrentClusterBytes
-                      << "\n");
-  }
-}
-
+    LLVM_DEBUG(dbgs() << "  Curr cluster length: " << ClusterLength 
+                      << ", Curr cluster bytes: " << CurrentClusterBytes 
+                      << "\n"); 
+  } 
+} 
+ 
 void BaseMemOpClusterMutation::collectMemOpRecords(
     std::vector<SUnit> &SUnits, SmallVectorImpl<MemOpInfo> &MemOpRecords) {
   for (auto &SU : SUnits) {
-    if ((IsLoad && !SU.getInstr()->mayLoad()) ||
-        (!IsLoad && !SU.getInstr()->mayStore()))
-      continue;
-
+    if ((IsLoad && !SU.getInstr()->mayLoad()) || 
+        (!IsLoad && !SU.getInstr()->mayStore())) 
+      continue; 
+ 
     const MachineInstr &MI = *SU.getInstr();
     SmallVector<const MachineOperand *, 4> BaseOps;
     int64_t Offset;
@@ -1713,7 +1713,7 @@ bool BaseMemOpClusterMutation::groupMemOps(
       MemOps.size() * DAG->SUnits.size() / 1000 > FastClusterThreshold;
 
   for (const auto &MemOp : MemOps) {
-    unsigned ChainPredID = DAG->SUnits.size();
+    unsigned ChainPredID = DAG->SUnits.size(); 
     if (FastCluster) {
       for (const SDep &Pred : MemOp.SU->Preds) {
         // We only want to cluster the mem ops that have the same ctrl(non-data)
@@ -1726,15 +1726,15 @@ bool BaseMemOpClusterMutation::groupMemOps(
           ChainPredID = Pred.getSUnit()->NodeNum;
           break;
         }
-      }
+      } 
     } else
       ChainPredID = 0;
 
     Groups[ChainPredID].push_back(MemOp);
-  }
+  } 
   return FastCluster;
 }
-
+ 
 /// Callback from DAG postProcessing to create cluster edges for loads/stores.
 void BaseMemOpClusterMutation::apply(ScheduleDAGInstrs *DAG) {
   // Collect all the clusterable loads/stores
@@ -1758,2148 +1758,2148 @@ void BaseMemOpClusterMutation::apply(ScheduleDAGInstrs *DAG) {
     // Trying to cluster all the neighboring loads/stores.
     clusterNeighboringMemOps(Group.second, FastCluster, DAG);
   }
-}
-
-//===----------------------------------------------------------------------===//
-// CopyConstrain - DAG post-processing to encourage copy elimination.
-//===----------------------------------------------------------------------===//
-
-namespace {
-
-/// Post-process the DAG to create weak edges from all uses of a copy to
-/// the one use that defines the copy's source vreg, most likely an induction
-/// variable increment.
-class CopyConstrain : public ScheduleDAGMutation {
-  // Transient state.
-  SlotIndex RegionBeginIdx;
-
-  // RegionEndIdx is the slot index of the last non-debug instruction in the
-  // scheduling region. So we may have RegionBeginIdx == RegionEndIdx.
-  SlotIndex RegionEndIdx;
-
-public:
-  CopyConstrain(const TargetInstrInfo *, const TargetRegisterInfo *) {}
-
-  void apply(ScheduleDAGInstrs *DAGInstrs) override;
-
-protected:
-  void constrainLocalCopy(SUnit *CopySU, ScheduleDAGMILive *DAG);
-};
-
-} // end anonymous namespace
-
-namespace llvm {
-
-std::unique_ptr<ScheduleDAGMutation>
-createCopyConstrainDAGMutation(const TargetInstrInfo *TII,
-                               const TargetRegisterInfo *TRI) {
-  return std::make_unique<CopyConstrain>(TII, TRI);
-}
-
-} // end namespace llvm
-
-/// constrainLocalCopy handles two possibilities:
-/// 1) Local src:
-/// I0:     = dst
-/// I1: src = ...
-/// I2:     = dst
-/// I3: dst = src (copy)
-/// (create pred->succ edges I0->I1, I2->I1)
-///
-/// 2) Local copy:
-/// I0: dst = src (copy)
-/// I1:     = dst
-/// I2: src = ...
-/// I3:     = dst
-/// (create pred->succ edges I1->I2, I3->I2)
-///
-/// Although the MachineScheduler is currently constrained to single blocks,
-/// this algorithm should handle extended blocks. An EBB is a set of
-/// contiguously numbered blocks such that the previous block in the EBB is
-/// always the single predecessor.
-void CopyConstrain::constrainLocalCopy(SUnit *CopySU, ScheduleDAGMILive *DAG) {
-  LiveIntervals *LIS = DAG->getLIS();
-  MachineInstr *Copy = CopySU->getInstr();
-
-  // Check for pure vreg copies.
-  const MachineOperand &SrcOp = Copy->getOperand(1);
-  Register SrcReg = SrcOp.getReg();
-  if (!Register::isVirtualRegister(SrcReg) || !SrcOp.readsReg())
-    return;
-
-  const MachineOperand &DstOp = Copy->getOperand(0);
-  Register DstReg = DstOp.getReg();
-  if (!Register::isVirtualRegister(DstReg) || DstOp.isDead())
-    return;
-
-  // Check if either the dest or source is local. If it's live across a back
-  // edge, it's not local. Note that if both vregs are live across the back
-  // edge, we cannot successfully contrain the copy without cyclic scheduling.
-  // If both the copy's source and dest are local live intervals, then we
-  // should treat the dest as the global for the purpose of adding
-  // constraints. This adds edges from source's other uses to the copy.
-  unsigned LocalReg = SrcReg;
-  unsigned GlobalReg = DstReg;
-  LiveInterval *LocalLI = &LIS->getInterval(LocalReg);
-  if (!LocalLI->isLocal(RegionBeginIdx, RegionEndIdx)) {
-    LocalReg = DstReg;
-    GlobalReg = SrcReg;
-    LocalLI = &LIS->getInterval(LocalReg);
-    if (!LocalLI->isLocal(RegionBeginIdx, RegionEndIdx))
-      return;
-  }
-  LiveInterval *GlobalLI = &LIS->getInterval(GlobalReg);
-
-  // Find the global segment after the start of the local LI.
-  LiveInterval::iterator GlobalSegment = GlobalLI->find(LocalLI->beginIndex());
-  // If GlobalLI does not overlap LocalLI->start, then a copy directly feeds a
-  // local live range. We could create edges from other global uses to the local
-  // start, but the coalescer should have already eliminated these cases, so
-  // don't bother dealing with it.
-  if (GlobalSegment == GlobalLI->end())
-    return;
-
-  // If GlobalSegment is killed at the LocalLI->start, the call to find()
-  // returned the next global segment. But if GlobalSegment overlaps with
-  // LocalLI->start, then advance to the next segment. If a hole in GlobalLI
-  // exists in LocalLI's vicinity, GlobalSegment will be the end of the hole.
-  if (GlobalSegment->contains(LocalLI->beginIndex()))
-    ++GlobalSegment;
-
-  if (GlobalSegment == GlobalLI->end())
-    return;
-
-  // Check if GlobalLI contains a hole in the vicinity of LocalLI.
-  if (GlobalSegment != GlobalLI->begin()) {
-    // Two address defs have no hole.
-    if (SlotIndex::isSameInstr(std::prev(GlobalSegment)->end,
-                               GlobalSegment->start)) {
-      return;
-    }
-    // If the prior global segment may be defined by the same two-address
-    // instruction that also defines LocalLI, then can't make a hole here.
-    if (SlotIndex::isSameInstr(std::prev(GlobalSegment)->start,
-                               LocalLI->beginIndex())) {
-      return;
-    }
-    // If GlobalLI has a prior segment, it must be live into the EBB. Otherwise
-    // it would be a disconnected component in the live range.
-    assert(std::prev(GlobalSegment)->start < LocalLI->beginIndex() &&
-           "Disconnected LRG within the scheduling region.");
-  }
-  MachineInstr *GlobalDef = LIS->getInstructionFromIndex(GlobalSegment->start);
-  if (!GlobalDef)
-    return;
-
-  SUnit *GlobalSU = DAG->getSUnit(GlobalDef);
-  if (!GlobalSU)
-    return;
-
-  // GlobalDef is the bottom of the GlobalLI hole. Open the hole by
-  // constraining the uses of the last local def to precede GlobalDef.
-  SmallVector<SUnit*,8> LocalUses;
-  const VNInfo *LastLocalVN = LocalLI->getVNInfoBefore(LocalLI->endIndex());
-  MachineInstr *LastLocalDef = LIS->getInstructionFromIndex(LastLocalVN->def);
-  SUnit *LastLocalSU = DAG->getSUnit(LastLocalDef);
-  for (const SDep &Succ : LastLocalSU->Succs) {
-    if (Succ.getKind() != SDep::Data || Succ.getReg() != LocalReg)
-      continue;
-    if (Succ.getSUnit() == GlobalSU)
-      continue;
-    if (!DAG->canAddEdge(GlobalSU, Succ.getSUnit()))
-      return;
-    LocalUses.push_back(Succ.getSUnit());
-  }
-  // Open the top of the GlobalLI hole by constraining any earlier global uses
-  // to precede the start of LocalLI.
-  SmallVector<SUnit*,8> GlobalUses;
-  MachineInstr *FirstLocalDef =
-    LIS->getInstructionFromIndex(LocalLI->beginIndex());
-  SUnit *FirstLocalSU = DAG->getSUnit(FirstLocalDef);
-  for (const SDep &Pred : GlobalSU->Preds) {
-    if (Pred.getKind() != SDep::Anti || Pred.getReg() != GlobalReg)
-      continue;
-    if (Pred.getSUnit() == FirstLocalSU)
-      continue;
-    if (!DAG->canAddEdge(FirstLocalSU, Pred.getSUnit()))
-      return;
-    GlobalUses.push_back(Pred.getSUnit());
-  }
-  LLVM_DEBUG(dbgs() << "Constraining copy SU(" << CopySU->NodeNum << ")\n");
-  // Add the weak edges.
-  for (SmallVectorImpl<SUnit*>::const_iterator
-         I = LocalUses.begin(), E = LocalUses.end(); I != E; ++I) {
-    LLVM_DEBUG(dbgs() << "  Local use SU(" << (*I)->NodeNum << ") -> SU("
-                      << GlobalSU->NodeNum << ")\n");
-    DAG->addEdge(GlobalSU, SDep(*I, SDep::Weak));
-  }
-  for (SmallVectorImpl<SUnit*>::const_iterator
-         I = GlobalUses.begin(), E = GlobalUses.end(); I != E; ++I) {
-    LLVM_DEBUG(dbgs() << "  Global use SU(" << (*I)->NodeNum << ") -> SU("
-                      << FirstLocalSU->NodeNum << ")\n");
-    DAG->addEdge(FirstLocalSU, SDep(*I, SDep::Weak));
-  }
-}
-
-/// Callback from DAG postProcessing to create weak edges to encourage
-/// copy elimination.
-void CopyConstrain::apply(ScheduleDAGInstrs *DAGInstrs) {
-  ScheduleDAGMI *DAG = static_cast<ScheduleDAGMI*>(DAGInstrs);
-  assert(DAG->hasVRegLiveness() && "Expect VRegs with LiveIntervals");
-
-  MachineBasicBlock::iterator FirstPos = nextIfDebug(DAG->begin(), DAG->end());
-  if (FirstPos == DAG->end())
-    return;
-  RegionBeginIdx = DAG->getLIS()->getInstructionIndex(*FirstPos);
-  RegionEndIdx = DAG->getLIS()->getInstructionIndex(
-      *priorNonDebug(DAG->end(), DAG->begin()));
-
-  for (SUnit &SU : DAG->SUnits) {
-    if (!SU.getInstr()->isCopy())
-      continue;
-
-    constrainLocalCopy(&SU, static_cast<ScheduleDAGMILive*>(DAG));
-  }
-}
-
-//===----------------------------------------------------------------------===//
-// MachineSchedStrategy helpers used by GenericScheduler, GenericPostScheduler
-// and possibly other custom schedulers.
-//===----------------------------------------------------------------------===//
-
-static const unsigned InvalidCycle = ~0U;
-
-SchedBoundary::~SchedBoundary() { delete HazardRec; }
-
-/// Given a Count of resource usage and a Latency value, return true if a
-/// SchedBoundary becomes resource limited.
-/// If we are checking after scheduling a node, we should return true when
-/// we just reach the resource limit.
-static bool checkResourceLimit(unsigned LFactor, unsigned Count,
-                               unsigned Latency, bool AfterSchedNode) {
-  int ResCntFactor = (int)(Count - (Latency * LFactor));
-  if (AfterSchedNode)
-    return ResCntFactor >= (int)LFactor;
-  else
-    return ResCntFactor > (int)LFactor;
-}
-
-void SchedBoundary::reset() {
-  // A new HazardRec is created for each DAG and owned by SchedBoundary.
-  // Destroying and reconstructing it is very expensive though. So keep
-  // invalid, placeholder HazardRecs.
-  if (HazardRec && HazardRec->isEnabled()) {
-    delete HazardRec;
-    HazardRec = nullptr;
-  }
-  Available.clear();
-  Pending.clear();
-  CheckPending = false;
-  CurrCycle = 0;
-  CurrMOps = 0;
-  MinReadyCycle = std::numeric_limits<unsigned>::max();
-  ExpectedLatency = 0;
-  DependentLatency = 0;
-  RetiredMOps = 0;
-  MaxExecutedResCount = 0;
-  ZoneCritResIdx = 0;
-  IsResourceLimited = false;
-  ReservedCycles.clear();
-  ReservedCyclesIndex.clear();
-#ifndef NDEBUG
-  // Track the maximum number of stall cycles that could arise either from the
-  // latency of a DAG edge or the number of cycles that a processor resource is
-  // reserved (SchedBoundary::ReservedCycles).
-  MaxObservedStall = 0;
-#endif
-  // Reserve a zero-count for invalid CritResIdx.
-  ExecutedResCounts.resize(1);
-  assert(!ExecutedResCounts[0] && "nonzero count for bad resource");
-}
-
-void SchedRemainder::
-init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel) {
-  reset();
-  if (!SchedModel->hasInstrSchedModel())
-    return;
-  RemainingCounts.resize(SchedModel->getNumProcResourceKinds());
-  for (SUnit &SU : DAG->SUnits) {
-    const MCSchedClassDesc *SC = DAG->getSchedClass(&SU);
-    RemIssueCount += SchedModel->getNumMicroOps(SU.getInstr(), SC)
-      * SchedModel->getMicroOpFactor();
-    for (TargetSchedModel::ProcResIter
-           PI = SchedModel->getWriteProcResBegin(SC),
-           PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) {
-      unsigned PIdx = PI->ProcResourceIdx;
-      unsigned Factor = SchedModel->getResourceFactor(PIdx);
-      RemainingCounts[PIdx] += (Factor * PI->Cycles);
-    }
-  }
-}
-
-void SchedBoundary::
-init(ScheduleDAGMI *dag, const TargetSchedModel *smodel, SchedRemainder *rem) {
-  reset();
-  DAG = dag;
-  SchedModel = smodel;
-  Rem = rem;
-  if (SchedModel->hasInstrSchedModel()) {
-    unsigned ResourceCount = SchedModel->getNumProcResourceKinds();
-    ReservedCyclesIndex.resize(ResourceCount);
-    ExecutedResCounts.resize(ResourceCount);
-    unsigned NumUnits = 0;
-
-    for (unsigned i = 0; i < ResourceCount; ++i) {
-      ReservedCyclesIndex[i] = NumUnits;
-      NumUnits += SchedModel->getProcResource(i)->NumUnits;
-    }
-
-    ReservedCycles.resize(NumUnits, InvalidCycle);
-  }
-}
-
-/// Compute the stall cycles based on this SUnit's ready time. Heuristics treat
-/// these "soft stalls" differently than the hard stall cycles based on CPU
-/// resources and computed by checkHazard(). A fully in-order model
-/// (MicroOpBufferSize==0) will not make use of this since instructions are not
-/// available for scheduling until they are ready. However, a weaker in-order
-/// model may use this for heuristics. For example, if a processor has in-order
-/// behavior when reading certain resources, this may come into play.
-unsigned SchedBoundary::getLatencyStallCycles(SUnit *SU) {
-  if (!SU->isUnbuffered)
-    return 0;
-
-  unsigned ReadyCycle = (isTop() ? SU->TopReadyCycle : SU->BotReadyCycle);
-  if (ReadyCycle > CurrCycle)
-    return ReadyCycle - CurrCycle;
-  return 0;
-}
-
-/// Compute the next cycle at which the given processor resource unit
-/// can be scheduled.
-unsigned SchedBoundary::getNextResourceCycleByInstance(unsigned InstanceIdx,
-                                                       unsigned Cycles) {
-  unsigned NextUnreserved = ReservedCycles[InstanceIdx];
-  // If this resource has never been used, always return cycle zero.
-  if (NextUnreserved == InvalidCycle)
-    return 0;
-  // For bottom-up scheduling add the cycles needed for the current operation.
-  if (!isTop())
-    NextUnreserved += Cycles;
-  return NextUnreserved;
-}
-
-/// Compute the next cycle at which the given processor resource can be
-/// scheduled.  Returns the next cycle and the index of the processor resource
-/// instance in the reserved cycles vector.
-std::pair<unsigned, unsigned>
-SchedBoundary::getNextResourceCycle(unsigned PIdx, unsigned Cycles) {
-  unsigned MinNextUnreserved = InvalidCycle;
-  unsigned InstanceIdx = 0;
-  unsigned StartIndex = ReservedCyclesIndex[PIdx];
-  unsigned NumberOfInstances = SchedModel->getProcResource(PIdx)->NumUnits;
-  assert(NumberOfInstances > 0 &&
-         "Cannot have zero instances of a ProcResource");
-
-  for (unsigned I = StartIndex, End = StartIndex + NumberOfInstances; I < End;
-       ++I) {
-    unsigned NextUnreserved = getNextResourceCycleByInstance(I, Cycles);
-    if (MinNextUnreserved > NextUnreserved) {
-      InstanceIdx = I;
-      MinNextUnreserved = NextUnreserved;
-    }
-  }
-  return std::make_pair(MinNextUnreserved, InstanceIdx);
-}
-
-/// Does this SU have a hazard within the current instruction group.
-///
-/// The scheduler supports two modes of hazard recognition. The first is the
-/// ScheduleHazardRecognizer API. It is a fully general hazard recognizer that
-/// supports highly complicated in-order reservation tables
-/// (ScoreboardHazardRecognizer) and arbitrary target-specific logic.
-///
-/// The second is a streamlined mechanism that checks for hazards based on
-/// simple counters that the scheduler itself maintains. It explicitly checks
-/// for instruction dispatch limitations, including the number of micro-ops that
-/// can dispatch per cycle.
-///
-/// TODO: Also check whether the SU must start a new group.
-bool SchedBoundary::checkHazard(SUnit *SU) {
-  if (HazardRec->isEnabled()
-      && HazardRec->getHazardType(SU) != ScheduleHazardRecognizer::NoHazard) {
-    return true;
-  }
-
-  unsigned uops = SchedModel->getNumMicroOps(SU->getInstr());
-  if ((CurrMOps > 0) && (CurrMOps + uops > SchedModel->getIssueWidth())) {
-    LLVM_DEBUG(dbgs() << "  SU(" << SU->NodeNum << ") uops="
-                      << SchedModel->getNumMicroOps(SU->getInstr()) << '\n');
-    return true;
-  }
-
-  if (CurrMOps > 0 &&
-      ((isTop() && SchedModel->mustBeginGroup(SU->getInstr())) ||
-       (!isTop() && SchedModel->mustEndGroup(SU->getInstr())))) {
-    LLVM_DEBUG(dbgs() << "  hazard: SU(" << SU->NodeNum << ") must "
-                      << (isTop() ? "begin" : "end") << " group\n");
-    return true;
-  }
-
-  if (SchedModel->hasInstrSchedModel() && SU->hasReservedResource) {
-    const MCSchedClassDesc *SC = DAG->getSchedClass(SU);
-    for (const MCWriteProcResEntry &PE :
-          make_range(SchedModel->getWriteProcResBegin(SC),
-                     SchedModel->getWriteProcResEnd(SC))) {
-      unsigned ResIdx = PE.ProcResourceIdx;
-      unsigned Cycles = PE.Cycles;
-      unsigned NRCycle, InstanceIdx;
-      std::tie(NRCycle, InstanceIdx) = getNextResourceCycle(ResIdx, Cycles);
-      if (NRCycle > CurrCycle) {
-#ifndef NDEBUG
-        MaxObservedStall = std::max(Cycles, MaxObservedStall);
-#endif
-        LLVM_DEBUG(dbgs() << "  SU(" << SU->NodeNum << ") "
-                          << SchedModel->getResourceName(ResIdx)
-                          << '[' << InstanceIdx - ReservedCyclesIndex[ResIdx]  << ']'
-                          << "=" << NRCycle << "c\n");
-        return true;
-      }
-    }
-  }
-  return false;
-}
-
-// Find the unscheduled node in ReadySUs with the highest latency.
-unsigned SchedBoundary::
-findMaxLatency(ArrayRef<SUnit*> ReadySUs) {
-  SUnit *LateSU = nullptr;
-  unsigned RemLatency = 0;
-  for (SUnit *SU : ReadySUs) {
-    unsigned L = getUnscheduledLatency(SU);
-    if (L > RemLatency) {
-      RemLatency = L;
-      LateSU = SU;
-    }
-  }
-  if (LateSU) {
-    LLVM_DEBUG(dbgs() << Available.getName() << " RemLatency SU("
-                      << LateSU->NodeNum << ") " << RemLatency << "c\n");
-  }
-  return RemLatency;
-}
-
-// Count resources in this zone and the remaining unscheduled
-// instruction. Return the max count, scaled. Set OtherCritIdx to the critical
-// resource index, or zero if the zone is issue limited.
-unsigned SchedBoundary::
-getOtherResourceCount(unsigned &OtherCritIdx) {
-  OtherCritIdx = 0;
-  if (!SchedModel->hasInstrSchedModel())
-    return 0;
-
-  unsigned OtherCritCount = Rem->RemIssueCount
-    + (RetiredMOps * SchedModel->getMicroOpFactor());
-  LLVM_DEBUG(dbgs() << "  " << Available.getName() << " + Remain MOps: "
-                    << OtherCritCount / SchedModel->getMicroOpFactor() << '\n');
-  for (unsigned PIdx = 1, PEnd = SchedModel->getNumProcResourceKinds();
-       PIdx != PEnd; ++PIdx) {
-    unsigned OtherCount = getResourceCount(PIdx) + Rem->RemainingCounts[PIdx];
-    if (OtherCount > OtherCritCount) {
-      OtherCritCount = OtherCount;
-      OtherCritIdx = PIdx;
-    }
-  }
-  if (OtherCritIdx) {
-    LLVM_DEBUG(
-        dbgs() << "  " << Available.getName() << " + Remain CritRes: "
-               << OtherCritCount / SchedModel->getResourceFactor(OtherCritIdx)
-               << " " << SchedModel->getResourceName(OtherCritIdx) << "\n");
-  }
-  return OtherCritCount;
-}
-
-void SchedBoundary::releaseNode(SUnit *SU, unsigned ReadyCycle, bool InPQueue,
-                                unsigned Idx) {
-  assert(SU->getInstr() && "Scheduled SUnit must have instr");
-
-#ifndef NDEBUG
-  // ReadyCycle was been bumped up to the CurrCycle when this node was
-  // scheduled, but CurrCycle may have been eagerly advanced immediately after
-  // scheduling, so may now be greater than ReadyCycle.
-  if (ReadyCycle > CurrCycle)
-    MaxObservedStall = std::max(ReadyCycle - CurrCycle, MaxObservedStall);
-#endif
-
-  if (ReadyCycle < MinReadyCycle)
-    MinReadyCycle = ReadyCycle;
-
-  // Check for interlocks first. For the purpose of other heuristics, an
-  // instruction that cannot issue appears as if it's not in the ReadyQueue.
-  bool IsBuffered = SchedModel->getMicroOpBufferSize() != 0;
-  bool HazardDetected = (!IsBuffered && ReadyCycle > CurrCycle) ||
-                        checkHazard(SU) || (Available.size() >= ReadyListLimit);
-
-  if (!HazardDetected) {
-    Available.push(SU);
-
-    if (InPQueue)
-      Pending.remove(Pending.begin() + Idx);
-    return;
-  }
-
-  if (!InPQueue)
-    Pending.push(SU);
-}
-
-/// Move the boundary of scheduled code by one cycle.
-void SchedBoundary::bumpCycle(unsigned NextCycle) {
-  if (SchedModel->getMicroOpBufferSize() == 0) {
-    assert(MinReadyCycle < std::numeric_limits<unsigned>::max() &&
-           "MinReadyCycle uninitialized");
-    if (MinReadyCycle > NextCycle)
-      NextCycle = MinReadyCycle;
-  }
-  // Update the current micro-ops, which will issue in the next cycle.
-  unsigned DecMOps = SchedModel->getIssueWidth() * (NextCycle - CurrCycle);
-  CurrMOps = (CurrMOps <= DecMOps) ? 0 : CurrMOps - DecMOps;
-
-  // Decrement DependentLatency based on the next cycle.
-  if ((NextCycle - CurrCycle) > DependentLatency)
-    DependentLatency = 0;
-  else
-    DependentLatency -= (NextCycle - CurrCycle);
-
-  if (!HazardRec->isEnabled()) {
-    // Bypass HazardRec virtual calls.
-    CurrCycle = NextCycle;
-  } else {
-    // Bypass getHazardType calls in case of long latency.
-    for (; CurrCycle != NextCycle; ++CurrCycle) {
-      if (isTop())
-        HazardRec->AdvanceCycle();
-      else
-        HazardRec->RecedeCycle();
-    }
-  }
-  CheckPending = true;
-  IsResourceLimited =
-      checkResourceLimit(SchedModel->getLatencyFactor(), getCriticalCount(),
-                         getScheduledLatency(), true);
-
-  LLVM_DEBUG(dbgs() << "Cycle: " << CurrCycle << ' ' << Available.getName()
-                    << '\n');
-}
-
-void SchedBoundary::incExecutedResources(unsigned PIdx, unsigned Count) {
-  ExecutedResCounts[PIdx] += Count;
-  if (ExecutedResCounts[PIdx] > MaxExecutedResCount)
-    MaxExecutedResCount = ExecutedResCounts[PIdx];
-}
-
-/// Add the given processor resource to this scheduled zone.
-///
-/// \param Cycles indicates the number of consecutive (non-pipelined) cycles
-/// during which this resource is consumed.
-///
-/// \return the next cycle at which the instruction may execute without
-/// oversubscribing resources.
-unsigned SchedBoundary::
-countResource(unsigned PIdx, unsigned Cycles, unsigned NextCycle) {
-  unsigned Factor = SchedModel->getResourceFactor(PIdx);
-  unsigned Count = Factor * Cycles;
-  LLVM_DEBUG(dbgs() << "  " << SchedModel->getResourceName(PIdx) << " +"
-                    << Cycles << "x" << Factor << "u\n");
-
-  // Update Executed resources counts.
-  incExecutedResources(PIdx, Count);
-  assert(Rem->RemainingCounts[PIdx] >= Count && "resource double counted");
-  Rem->RemainingCounts[PIdx] -= Count;
-
-  // Check if this resource exceeds the current critical resource. If so, it
-  // becomes the critical resource.
-  if (ZoneCritResIdx != PIdx && (getResourceCount(PIdx) > getCriticalCount())) {
-    ZoneCritResIdx = PIdx;
-    LLVM_DEBUG(dbgs() << "  *** Critical resource "
-                      << SchedModel->getResourceName(PIdx) << ": "
-                      << getResourceCount(PIdx) / SchedModel->getLatencyFactor()
-                      << "c\n");
-  }
-  // For reserved resources, record the highest cycle using the resource.
-  unsigned NextAvailable, InstanceIdx;
-  std::tie(NextAvailable, InstanceIdx) = getNextResourceCycle(PIdx, Cycles);
-  if (NextAvailable > CurrCycle) {
-    LLVM_DEBUG(dbgs() << "  Resource conflict: "
-                      << SchedModel->getResourceName(PIdx)
-                      << '[' << InstanceIdx - ReservedCyclesIndex[PIdx]  << ']'
-                      << " reserved until @" << NextAvailable << "\n");
-  }
-  return NextAvailable;
-}
-
-/// Move the boundary of scheduled code by one SUnit.
-void SchedBoundary::bumpNode(SUnit *SU) {
-  // Update the reservation table.
-  if (HazardRec->isEnabled()) {
-    if (!isTop() && SU->isCall) {
-      // Calls are scheduled with their preceding instructions. For bottom-up
-      // scheduling, clear the pipeline state before emitting.
-      HazardRec->Reset();
-    }
-    HazardRec->EmitInstruction(SU);
-    // Scheduling an instruction may have made pending instructions available.
-    CheckPending = true;
-  }
-  // checkHazard should prevent scheduling multiple instructions per cycle that
-  // exceed the issue width.
-  const MCSchedClassDesc *SC = DAG->getSchedClass(SU);
-  unsigned IncMOps = SchedModel->getNumMicroOps(SU->getInstr());
-  assert(
-      (CurrMOps == 0 || (CurrMOps + IncMOps) <= SchedModel->getIssueWidth()) &&
-      "Cannot schedule this instruction's MicroOps in the current cycle.");
-
-  unsigned ReadyCycle = (isTop() ? SU->TopReadyCycle : SU->BotReadyCycle);
-  LLVM_DEBUG(dbgs() << "  Ready @" << ReadyCycle << "c\n");
-
-  unsigned NextCycle = CurrCycle;
-  switch (SchedModel->getMicroOpBufferSize()) {
-  case 0:
-    assert(ReadyCycle <= CurrCycle && "Broken PendingQueue");
-    break;
-  case 1:
-    if (ReadyCycle > NextCycle) {
-      NextCycle = ReadyCycle;
-      LLVM_DEBUG(dbgs() << "  *** Stall until: " << ReadyCycle << "\n");
-    }
-    break;
-  default:
-    // We don't currently model the OOO reorder buffer, so consider all
-    // scheduled MOps to be "retired". We do loosely model in-order resource
-    // latency. If this instruction uses an in-order resource, account for any
-    // likely stall cycles.
-    if (SU->isUnbuffered && ReadyCycle > NextCycle)
-      NextCycle = ReadyCycle;
-    break;
-  }
-  RetiredMOps += IncMOps;
-
-  // Update resource counts and critical resource.
-  if (SchedModel->hasInstrSchedModel()) {
-    unsigned DecRemIssue = IncMOps * SchedModel->getMicroOpFactor();
-    assert(Rem->RemIssueCount >= DecRemIssue && "MOps double counted");
-    Rem->RemIssueCount -= DecRemIssue;
-    if (ZoneCritResIdx) {
-      // Scale scheduled micro-ops for comparing with the critical resource.
-      unsigned ScaledMOps =
-        RetiredMOps * SchedModel->getMicroOpFactor();
-
-      // If scaled micro-ops are now more than the previous critical resource by
-      // a full cycle, then micro-ops issue becomes critical.
-      if ((int)(ScaledMOps - getResourceCount(ZoneCritResIdx))
-          >= (int)SchedModel->getLatencyFactor()) {
-        ZoneCritResIdx = 0;
-        LLVM_DEBUG(dbgs() << "  *** Critical resource NumMicroOps: "
-                          << ScaledMOps / SchedModel->getLatencyFactor()
-                          << "c\n");
-      }
-    }
-    for (TargetSchedModel::ProcResIter
-           PI = SchedModel->getWriteProcResBegin(SC),
-           PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) {
-      unsigned RCycle =
-        countResource(PI->ProcResourceIdx, PI->Cycles, NextCycle);
-      if (RCycle > NextCycle)
-        NextCycle = RCycle;
-    }
-    if (SU->hasReservedResource) {
-      // For reserved resources, record the highest cycle using the resource.
-      // For top-down scheduling, this is the cycle in which we schedule this
-      // instruction plus the number of cycles the operations reserves the
-      // resource. For bottom-up is it simply the instruction's cycle.
-      for (TargetSchedModel::ProcResIter
-             PI = SchedModel->getWriteProcResBegin(SC),
-             PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) {
-        unsigned PIdx = PI->ProcResourceIdx;
-        if (SchedModel->getProcResource(PIdx)->BufferSize == 0) {
-          unsigned ReservedUntil, InstanceIdx;
-          std::tie(ReservedUntil, InstanceIdx) = getNextResourceCycle(PIdx, 0);
-          if (isTop()) {
-            ReservedCycles[InstanceIdx] =
-                std::max(ReservedUntil, NextCycle + PI->Cycles);
-          } else
-            ReservedCycles[InstanceIdx] = NextCycle;
-        }
-      }
-    }
-  }
-  // Update ExpectedLatency and DependentLatency.
-  unsigned &TopLatency = isTop() ? ExpectedLatency : DependentLatency;
-  unsigned &BotLatency = isTop() ? DependentLatency : ExpectedLatency;
-  if (SU->getDepth() > TopLatency) {
-    TopLatency = SU->getDepth();
-    LLVM_DEBUG(dbgs() << "  " << Available.getName() << " TopLatency SU("
-                      << SU->NodeNum << ") " << TopLatency << "c\n");
-  }
-  if (SU->getHeight() > BotLatency) {
-    BotLatency = SU->getHeight();
-    LLVM_DEBUG(dbgs() << "  " << Available.getName() << " BotLatency SU("
-                      << SU->NodeNum << ") " << BotLatency << "c\n");
-  }
-  // If we stall for any reason, bump the cycle.
-  if (NextCycle > CurrCycle)
-    bumpCycle(NextCycle);
-  else
-    // After updating ZoneCritResIdx and ExpectedLatency, check if we're
-    // resource limited. If a stall occurred, bumpCycle does this.
-    IsResourceLimited =
-        checkResourceLimit(SchedModel->getLatencyFactor(), getCriticalCount(),
-                           getScheduledLatency(), true);
-
-  // Update CurrMOps after calling bumpCycle to handle stalls, since bumpCycle
-  // resets CurrMOps. Loop to handle instructions with more MOps than issue in
-  // one cycle.  Since we commonly reach the max MOps here, opportunistically
-  // bump the cycle to avoid uselessly checking everything in the readyQ.
-  CurrMOps += IncMOps;
-
-  // Bump the cycle count for issue group constraints.
-  // This must be done after NextCycle has been adjust for all other stalls.
-  // Calling bumpCycle(X) will reduce CurrMOps by one issue group and set
-  // currCycle to X.
-  if ((isTop() &&  SchedModel->mustEndGroup(SU->getInstr())) ||
-      (!isTop() && SchedModel->mustBeginGroup(SU->getInstr()))) {
-    LLVM_DEBUG(dbgs() << "  Bump cycle to " << (isTop() ? "end" : "begin")
-                      << " group\n");
-    bumpCycle(++NextCycle);
-  }
-
-  while (CurrMOps >= SchedModel->getIssueWidth()) {
-    LLVM_DEBUG(dbgs() << "  *** Max MOps " << CurrMOps << " at cycle "
-                      << CurrCycle << '\n');
-    bumpCycle(++NextCycle);
-  }
-  LLVM_DEBUG(dumpScheduledState());
-}
-
-/// Release pending ready nodes in to the available queue. This makes them
-/// visible to heuristics.
-void SchedBoundary::releasePending() {
-  // If the available queue is empty, it is safe to reset MinReadyCycle.
-  if (Available.empty())
-    MinReadyCycle = std::numeric_limits<unsigned>::max();
-
-  // Check to see if any of the pending instructions are ready to issue.  If
-  // so, add them to the available queue.
-  for (unsigned I = 0, E = Pending.size(); I < E; ++I) {
-    SUnit *SU = *(Pending.begin() + I);
-    unsigned ReadyCycle = isTop() ? SU->TopReadyCycle : SU->BotReadyCycle;
-
-    if (ReadyCycle < MinReadyCycle)
-      MinReadyCycle = ReadyCycle;
-
-    if (Available.size() >= ReadyListLimit)
-      break;
-
-    releaseNode(SU, ReadyCycle, true, I);
-    if (E != Pending.size()) {
-      --I;
-      --E;
-    }
-  }
-  CheckPending = false;
-}
-
-/// Remove SU from the ready set for this boundary.
-void SchedBoundary::removeReady(SUnit *SU) {
-  if (Available.isInQueue(SU))
-    Available.remove(Available.find(SU));
-  else {
-    assert(Pending.isInQueue(SU) && "bad ready count");
-    Pending.remove(Pending.find(SU));
-  }
-}
-
-/// If this queue only has one ready candidate, return it. As a side effect,
-/// defer any nodes that now hit a hazard, and advance the cycle until at least
-/// one node is ready. If multiple instructions are ready, return NULL.
-SUnit *SchedBoundary::pickOnlyChoice() {
-  if (CheckPending)
-    releasePending();
-
-  // Defer any ready instrs that now have a hazard.
-  for (ReadyQueue::iterator I = Available.begin(); I != Available.end();) {
-    if (checkHazard(*I)) {
-      Pending.push(*I);
-      I = Available.remove(I);
-      continue;
-    }
-    ++I;
-  }
-  for (unsigned i = 0; Available.empty(); ++i) {
-//  FIXME: Re-enable assert once PR20057 is resolved.
-//    assert(i <= (HazardRec->getMaxLookAhead() + MaxObservedStall) &&
-//           "permanent hazard");
-    (void)i;
-    bumpCycle(CurrCycle + 1);
-    releasePending();
-  }
-
-  LLVM_DEBUG(Pending.dump());
-  LLVM_DEBUG(Available.dump());
-
-  if (Available.size() == 1)
-    return *Available.begin();
-  return nullptr;
-}
-
-#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-// This is useful information to dump after bumpNode.
-// Note that the Queue contents are more useful before pickNodeFromQueue.
-LLVM_DUMP_METHOD void SchedBoundary::dumpScheduledState() const {
-  unsigned ResFactor;
-  unsigned ResCount;
-  if (ZoneCritResIdx) {
-    ResFactor = SchedModel->getResourceFactor(ZoneCritResIdx);
-    ResCount = getResourceCount(ZoneCritResIdx);
-  } else {
-    ResFactor = SchedModel->getMicroOpFactor();
-    ResCount = RetiredMOps * ResFactor;
-  }
-  unsigned LFactor = SchedModel->getLatencyFactor();
-  dbgs() << Available.getName() << " @" << CurrCycle << "c\n"
-         << "  Retired: " << RetiredMOps;
-  dbgs() << "\n  Executed: " << getExecutedCount() / LFactor << "c";
-  dbgs() << "\n  Critical: " << ResCount / LFactor << "c, "
-         << ResCount / ResFactor << " "
-         << SchedModel->getResourceName(ZoneCritResIdx)
-         << "\n  ExpectedLatency: " << ExpectedLatency << "c\n"
-         << (IsResourceLimited ? "  - Resource" : "  - Latency")
-         << " limited.\n";
-}
-#endif
-
-//===----------------------------------------------------------------------===//
-// GenericScheduler - Generic implementation of MachineSchedStrategy.
-//===----------------------------------------------------------------------===//
-
-void GenericSchedulerBase::SchedCandidate::
-initResourceDelta(const ScheduleDAGMI *DAG,
-                  const TargetSchedModel *SchedModel) {
-  if (!Policy.ReduceResIdx && !Policy.DemandResIdx)
-    return;
-
-  const MCSchedClassDesc *SC = DAG->getSchedClass(SU);
-  for (TargetSchedModel::ProcResIter
-         PI = SchedModel->getWriteProcResBegin(SC),
-         PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) {
-    if (PI->ProcResourceIdx == Policy.ReduceResIdx)
-      ResDelta.CritResources += PI->Cycles;
-    if (PI->ProcResourceIdx == Policy.DemandResIdx)
-      ResDelta.DemandedResources += PI->Cycles;
-  }
-}
-
-/// Compute remaining latency. We need this both to determine whether the
-/// overall schedule has become latency-limited and whether the instructions
-/// outside this zone are resource or latency limited.
-///
-/// The "dependent" latency is updated incrementally during scheduling as the
-/// max height/depth of scheduled nodes minus the cycles since it was
-/// scheduled:
-///   DLat = max (N.depth - (CurrCycle - N.ReadyCycle) for N in Zone
-///
-/// The "independent" latency is the max ready queue depth:
-///   ILat = max N.depth for N in Available|Pending
-///
-/// RemainingLatency is the greater of independent and dependent latency.
-///
-/// These computations are expensive, especially in DAGs with many edges, so
-/// only do them if necessary.
-static unsigned computeRemLatency(SchedBoundary &CurrZone) {
-  unsigned RemLatency = CurrZone.getDependentLatency();
-  RemLatency = std::max(RemLatency,
-                        CurrZone.findMaxLatency(CurrZone.Available.elements()));
-  RemLatency = std::max(RemLatency,
-                        CurrZone.findMaxLatency(CurrZone.Pending.elements()));
-  return RemLatency;
-}
-
-/// Returns true if the current cycle plus remaning latency is greater than
-/// the critical path in the scheduling region.
-bool GenericSchedulerBase::shouldReduceLatency(const CandPolicy &Policy,
-                                               SchedBoundary &CurrZone,
-                                               bool ComputeRemLatency,
-                                               unsigned &RemLatency) const {
-  // The current cycle is already greater than the critical path, so we are
-  // already latency limited and don't need to compute the remaining latency.
-  if (CurrZone.getCurrCycle() > Rem.CriticalPath)
-    return true;
-
-  // If we haven't scheduled anything yet, then we aren't latency limited.
-  if (CurrZone.getCurrCycle() == 0)
-    return false;
-
-  if (ComputeRemLatency)
-    RemLatency = computeRemLatency(CurrZone);
-
-  return RemLatency + CurrZone.getCurrCycle() > Rem.CriticalPath;
-}
-
-/// Set the CandPolicy given a scheduling zone given the current resources and
-/// latencies inside and outside the zone.
-void GenericSchedulerBase::setPolicy(CandPolicy &Policy, bool IsPostRA,
-                                     SchedBoundary &CurrZone,
-                                     SchedBoundary *OtherZone) {
-  // Apply preemptive heuristics based on the total latency and resources
-  // inside and outside this zone. Potential stalls should be considered before
-  // following this policy.
-
-  // Compute the critical resource outside the zone.
-  unsigned OtherCritIdx = 0;
-  unsigned OtherCount =
-    OtherZone ? OtherZone->getOtherResourceCount(OtherCritIdx) : 0;
-
-  bool OtherResLimited = false;
-  unsigned RemLatency = 0;
-  bool RemLatencyComputed = false;
-  if (SchedModel->hasInstrSchedModel() && OtherCount != 0) {
-    RemLatency = computeRemLatency(CurrZone);
-    RemLatencyComputed = true;
-    OtherResLimited = checkResourceLimit(SchedModel->getLatencyFactor(),
-                                         OtherCount, RemLatency, false);
-  }
-
-  // Schedule aggressively for latency in PostRA mode. We don't check for
-  // acyclic latency during PostRA, and highly out-of-order processors will
-  // skip PostRA scheduling.
-  if (!OtherResLimited &&
-      (IsPostRA || shouldReduceLatency(Policy, CurrZone, !RemLatencyComputed,
-                                       RemLatency))) {
-    Policy.ReduceLatency |= true;
-    LLVM_DEBUG(dbgs() << "  " << CurrZone.Available.getName()
-                      << " RemainingLatency " << RemLatency << " + "
-                      << CurrZone.getCurrCycle() << "c > CritPath "
-                      << Rem.CriticalPath << "\n");
-  }
-  // If the same resource is limiting inside and outside the zone, do nothing.
-  if (CurrZone.getZoneCritResIdx() == OtherCritIdx)
-    return;
-
-  LLVM_DEBUG(if (CurrZone.isResourceLimited()) {
-    dbgs() << "  " << CurrZone.Available.getName() << " ResourceLimited: "
-           << SchedModel->getResourceName(CurrZone.getZoneCritResIdx()) << "\n";
-  } if (OtherResLimited) dbgs()
-                 << "  RemainingLimit: "
-                 << SchedModel->getResourceName(OtherCritIdx) << "\n";
-             if (!CurrZone.isResourceLimited() && !OtherResLimited) dbgs()
-             << "  Latency limited both directions.\n");
-
-  if (CurrZone.isResourceLimited() && !Policy.ReduceResIdx)
-    Policy.ReduceResIdx = CurrZone.getZoneCritResIdx();
-
-  if (OtherResLimited)
-    Policy.DemandResIdx = OtherCritIdx;
-}
-
-#ifndef NDEBUG
-const char *GenericSchedulerBase::getReasonStr(
-  GenericSchedulerBase::CandReason Reason) {
-  switch (Reason) {
-  case NoCand:         return "NOCAND    ";
-  case Only1:          return "ONLY1     ";
-  case PhysReg:        return "PHYS-REG  ";
-  case RegExcess:      return "REG-EXCESS";
-  case RegCritical:    return "REG-CRIT  ";
-  case Stall:          return "STALL     ";
-  case Cluster:        return "CLUSTER   ";
-  case Weak:           return "WEAK      ";
-  case RegMax:         return "REG-MAX   ";
-  case ResourceReduce: return "RES-REDUCE";
-  case ResourceDemand: return "RES-DEMAND";
-  case TopDepthReduce: return "TOP-DEPTH ";
-  case TopPathReduce:  return "TOP-PATH  ";
-  case BotHeightReduce:return "BOT-HEIGHT";
-  case BotPathReduce:  return "BOT-PATH  ";
-  case NextDefUse:     return "DEF-USE   ";
-  case NodeOrder:      return "ORDER     ";
-  };
-  llvm_unreachable("Unknown reason!");
-}
-
-void GenericSchedulerBase::traceCandidate(const SchedCandidate &Cand) {
-  PressureChange P;
-  unsigned ResIdx = 0;
-  unsigned Latency = 0;
-  switch (Cand.Reason) {
-  default:
-    break;
-  case RegExcess:
-    P = Cand.RPDelta.Excess;
-    break;
-  case RegCritical:
-    P = Cand.RPDelta.CriticalMax;
-    break;
-  case RegMax:
-    P = Cand.RPDelta.CurrentMax;
-    break;
-  case ResourceReduce:
-    ResIdx = Cand.Policy.ReduceResIdx;
-    break;
-  case ResourceDemand:
-    ResIdx = Cand.Policy.DemandResIdx;
-    break;
-  case TopDepthReduce:
-    Latency = Cand.SU->getDepth();
-    break;
-  case TopPathReduce:
-    Latency = Cand.SU->getHeight();
-    break;
-  case BotHeightReduce:
-    Latency = Cand.SU->getHeight();
-    break;
-  case BotPathReduce:
-    Latency = Cand.SU->getDepth();
-    break;
-  }
-  dbgs() << "  Cand SU(" << Cand.SU->NodeNum << ") " << getReasonStr(Cand.Reason);
-  if (P.isValid())
-    dbgs() << " " << TRI->getRegPressureSetName(P.getPSet())
-           << ":" << P.getUnitInc() << " ";
-  else
-    dbgs() << "      ";
-  if (ResIdx)
-    dbgs() << " " << SchedModel->getProcResource(ResIdx)->Name << " ";
-  else
-    dbgs() << "         ";
-  if (Latency)
-    dbgs() << " " << Latency << " cycles ";
-  else
-    dbgs() << "          ";
-  dbgs() << '\n';
-}
-#endif
-
-namespace llvm {
-/// Return true if this heuristic determines order.
-bool tryLess(int TryVal, int CandVal,
-             GenericSchedulerBase::SchedCandidate &TryCand,
-             GenericSchedulerBase::SchedCandidate &Cand,
-             GenericSchedulerBase::CandReason Reason) {
-  if (TryVal < CandVal) {
-    TryCand.Reason = Reason;
-    return true;
-  }
-  if (TryVal > CandVal) {
-    if (Cand.Reason > Reason)
-      Cand.Reason = Reason;
-    return true;
-  }
-  return false;
-}
-
-bool tryGreater(int TryVal, int CandVal,
-                GenericSchedulerBase::SchedCandidate &TryCand,
-                GenericSchedulerBase::SchedCandidate &Cand,
-                GenericSchedulerBase::CandReason Reason) {
-  if (TryVal > CandVal) {
-    TryCand.Reason = Reason;
-    return true;
-  }
-  if (TryVal < CandVal) {
-    if (Cand.Reason > Reason)
-      Cand.Reason = Reason;
-    return true;
-  }
-  return false;
-}
-
-bool tryLatency(GenericSchedulerBase::SchedCandidate &TryCand,
-                GenericSchedulerBase::SchedCandidate &Cand,
-                SchedBoundary &Zone) {
-  if (Zone.isTop()) {
+} 
+ 
+//===----------------------------------------------------------------------===// 
+// CopyConstrain - DAG post-processing to encourage copy elimination. 
+//===----------------------------------------------------------------------===// 
+ 
+namespace { 
+ 
+/// Post-process the DAG to create weak edges from all uses of a copy to 
+/// the one use that defines the copy's source vreg, most likely an induction 
+/// variable increment. 
+class CopyConstrain : public ScheduleDAGMutation { 
+  // Transient state. 
+  SlotIndex RegionBeginIdx; 
+ 
+  // RegionEndIdx is the slot index of the last non-debug instruction in the 
+  // scheduling region. So we may have RegionBeginIdx == RegionEndIdx. 
+  SlotIndex RegionEndIdx; 
+ 
+public: 
+  CopyConstrain(const TargetInstrInfo *, const TargetRegisterInfo *) {} 
+ 
+  void apply(ScheduleDAGInstrs *DAGInstrs) override; 
+ 
+protected: 
+  void constrainLocalCopy(SUnit *CopySU, ScheduleDAGMILive *DAG); 
+}; 
+ 
+} // end anonymous namespace 
+ 
+namespace llvm { 
+ 
+std::unique_ptr<ScheduleDAGMutation> 
+createCopyConstrainDAGMutation(const TargetInstrInfo *TII, 
+                               const TargetRegisterInfo *TRI) { 
+  return std::make_unique<CopyConstrain>(TII, TRI); 
+} 
+ 
+} // end namespace llvm 
+ 
+/// constrainLocalCopy handles two possibilities: 
+/// 1) Local src: 
+/// I0:     = dst 
+/// I1: src = ... 
+/// I2:     = dst 
+/// I3: dst = src (copy) 
+/// (create pred->succ edges I0->I1, I2->I1) 
+/// 
+/// 2) Local copy: 
+/// I0: dst = src (copy) 
+/// I1:     = dst 
+/// I2: src = ... 
+/// I3:     = dst 
+/// (create pred->succ edges I1->I2, I3->I2) 
+/// 
+/// Although the MachineScheduler is currently constrained to single blocks, 
+/// this algorithm should handle extended blocks. An EBB is a set of 
+/// contiguously numbered blocks such that the previous block in the EBB is 
+/// always the single predecessor. 
+void CopyConstrain::constrainLocalCopy(SUnit *CopySU, ScheduleDAGMILive *DAG) { 
+  LiveIntervals *LIS = DAG->getLIS(); 
+  MachineInstr *Copy = CopySU->getInstr(); 
+ 
+  // Check for pure vreg copies. 
+  const MachineOperand &SrcOp = Copy->getOperand(1); 
+  Register SrcReg = SrcOp.getReg(); 
+  if (!Register::isVirtualRegister(SrcReg) || !SrcOp.readsReg()) 
+    return; 
+ 
+  const MachineOperand &DstOp = Copy->getOperand(0); 
+  Register DstReg = DstOp.getReg(); 
+  if (!Register::isVirtualRegister(DstReg) || DstOp.isDead()) 
+    return; 
+ 
+  // Check if either the dest or source is local. If it's live across a back 
+  // edge, it's not local. Note that if both vregs are live across the back 
+  // edge, we cannot successfully contrain the copy without cyclic scheduling. 
+  // If both the copy's source and dest are local live intervals, then we 
+  // should treat the dest as the global for the purpose of adding 
+  // constraints. This adds edges from source's other uses to the copy. 
+  unsigned LocalReg = SrcReg; 
+  unsigned GlobalReg = DstReg; 
+  LiveInterval *LocalLI = &LIS->getInterval(LocalReg); 
+  if (!LocalLI->isLocal(RegionBeginIdx, RegionEndIdx)) { 
+    LocalReg = DstReg; 
+    GlobalReg = SrcReg; 
+    LocalLI = &LIS->getInterval(LocalReg); 
+    if (!LocalLI->isLocal(RegionBeginIdx, RegionEndIdx)) 
+      return; 
+  } 
+  LiveInterval *GlobalLI = &LIS->getInterval(GlobalReg); 
+ 
+  // Find the global segment after the start of the local LI. 
+  LiveInterval::iterator GlobalSegment = GlobalLI->find(LocalLI->beginIndex()); 
+  // If GlobalLI does not overlap LocalLI->start, then a copy directly feeds a 
+  // local live range. We could create edges from other global uses to the local 
+  // start, but the coalescer should have already eliminated these cases, so 
+  // don't bother dealing with it. 
+  if (GlobalSegment == GlobalLI->end()) 
+    return; 
+ 
+  // If GlobalSegment is killed at the LocalLI->start, the call to find() 
+  // returned the next global segment. But if GlobalSegment overlaps with 
+  // LocalLI->start, then advance to the next segment. If a hole in GlobalLI 
+  // exists in LocalLI's vicinity, GlobalSegment will be the end of the hole. 
+  if (GlobalSegment->contains(LocalLI->beginIndex())) 
+    ++GlobalSegment; 
+ 
+  if (GlobalSegment == GlobalLI->end()) 
+    return; 
+ 
+  // Check if GlobalLI contains a hole in the vicinity of LocalLI. 
+  if (GlobalSegment != GlobalLI->begin()) { 
+    // Two address defs have no hole. 
+    if (SlotIndex::isSameInstr(std::prev(GlobalSegment)->end, 
+                               GlobalSegment->start)) { 
+      return; 
+    } 
+    // If the prior global segment may be defined by the same two-address 
+    // instruction that also defines LocalLI, then can't make a hole here. 
+    if (SlotIndex::isSameInstr(std::prev(GlobalSegment)->start, 
+                               LocalLI->beginIndex())) { 
+      return; 
+    } 
+    // If GlobalLI has a prior segment, it must be live into the EBB. Otherwise 
+    // it would be a disconnected component in the live range. 
+    assert(std::prev(GlobalSegment)->start < LocalLI->beginIndex() && 
+           "Disconnected LRG within the scheduling region."); 
+  } 
+  MachineInstr *GlobalDef = LIS->getInstructionFromIndex(GlobalSegment->start); 
+  if (!GlobalDef) 
+    return; 
+ 
+  SUnit *GlobalSU = DAG->getSUnit(GlobalDef); 
+  if (!GlobalSU) 
+    return; 
+ 
+  // GlobalDef is the bottom of the GlobalLI hole. Open the hole by 
+  // constraining the uses of the last local def to precede GlobalDef. 
+  SmallVector<SUnit*,8> LocalUses; 
+  const VNInfo *LastLocalVN = LocalLI->getVNInfoBefore(LocalLI->endIndex()); 
+  MachineInstr *LastLocalDef = LIS->getInstructionFromIndex(LastLocalVN->def); 
+  SUnit *LastLocalSU = DAG->getSUnit(LastLocalDef); 
+  for (const SDep &Succ : LastLocalSU->Succs) { 
+    if (Succ.getKind() != SDep::Data || Succ.getReg() != LocalReg) 
+      continue; 
+    if (Succ.getSUnit() == GlobalSU) 
+      continue; 
+    if (!DAG->canAddEdge(GlobalSU, Succ.getSUnit())) 
+      return; 
+    LocalUses.push_back(Succ.getSUnit()); 
+  } 
+  // Open the top of the GlobalLI hole by constraining any earlier global uses 
+  // to precede the start of LocalLI. 
+  SmallVector<SUnit*,8> GlobalUses; 
+  MachineInstr *FirstLocalDef = 
+    LIS->getInstructionFromIndex(LocalLI->beginIndex()); 
+  SUnit *FirstLocalSU = DAG->getSUnit(FirstLocalDef); 
+  for (const SDep &Pred : GlobalSU->Preds) { 
+    if (Pred.getKind() != SDep::Anti || Pred.getReg() != GlobalReg) 
+      continue; 
+    if (Pred.getSUnit() == FirstLocalSU) 
+      continue; 
+    if (!DAG->canAddEdge(FirstLocalSU, Pred.getSUnit())) 
+      return; 
+    GlobalUses.push_back(Pred.getSUnit()); 
+  } 
+  LLVM_DEBUG(dbgs() << "Constraining copy SU(" << CopySU->NodeNum << ")\n"); 
+  // Add the weak edges. 
+  for (SmallVectorImpl<SUnit*>::const_iterator 
+         I = LocalUses.begin(), E = LocalUses.end(); I != E; ++I) { 
+    LLVM_DEBUG(dbgs() << "  Local use SU(" << (*I)->NodeNum << ") -> SU(" 
+                      << GlobalSU->NodeNum << ")\n"); 
+    DAG->addEdge(GlobalSU, SDep(*I, SDep::Weak)); 
+  } 
+  for (SmallVectorImpl<SUnit*>::const_iterator 
+         I = GlobalUses.begin(), E = GlobalUses.end(); I != E; ++I) { 
+    LLVM_DEBUG(dbgs() << "  Global use SU(" << (*I)->NodeNum << ") -> SU(" 
+                      << FirstLocalSU->NodeNum << ")\n"); 
+    DAG->addEdge(FirstLocalSU, SDep(*I, SDep::Weak)); 
+  } 
+} 
+ 
+/// Callback from DAG postProcessing to create weak edges to encourage 
+/// copy elimination. 
+void CopyConstrain::apply(ScheduleDAGInstrs *DAGInstrs) { 
+  ScheduleDAGMI *DAG = static_cast<ScheduleDAGMI*>(DAGInstrs); 
+  assert(DAG->hasVRegLiveness() && "Expect VRegs with LiveIntervals"); 
+ 
+  MachineBasicBlock::iterator FirstPos = nextIfDebug(DAG->begin(), DAG->end()); 
+  if (FirstPos == DAG->end()) 
+    return; 
+  RegionBeginIdx = DAG->getLIS()->getInstructionIndex(*FirstPos); 
+  RegionEndIdx = DAG->getLIS()->getInstructionIndex( 
+      *priorNonDebug(DAG->end(), DAG->begin())); 
+ 
+  for (SUnit &SU : DAG->SUnits) { 
+    if (!SU.getInstr()->isCopy()) 
+      continue; 
+ 
+    constrainLocalCopy(&SU, static_cast<ScheduleDAGMILive*>(DAG)); 
+  } 
+} 
+ 
+//===----------------------------------------------------------------------===// 
+// MachineSchedStrategy helpers used by GenericScheduler, GenericPostScheduler 
+// and possibly other custom schedulers. 
+//===----------------------------------------------------------------------===// 
+ 
+static const unsigned InvalidCycle = ~0U; 
+ 
+SchedBoundary::~SchedBoundary() { delete HazardRec; } 
+ 
+/// Given a Count of resource usage and a Latency value, return true if a 
+/// SchedBoundary becomes resource limited. 
+/// If we are checking after scheduling a node, we should return true when 
+/// we just reach the resource limit. 
+static bool checkResourceLimit(unsigned LFactor, unsigned Count, 
+                               unsigned Latency, bool AfterSchedNode) { 
+  int ResCntFactor = (int)(Count - (Latency * LFactor)); 
+  if (AfterSchedNode) 
+    return ResCntFactor >= (int)LFactor; 
+  else 
+    return ResCntFactor > (int)LFactor; 
+} 
+ 
+void SchedBoundary::reset() { 
+  // A new HazardRec is created for each DAG and owned by SchedBoundary. 
+  // Destroying and reconstructing it is very expensive though. So keep 
+  // invalid, placeholder HazardRecs. 
+  if (HazardRec && HazardRec->isEnabled()) { 
+    delete HazardRec; 
+    HazardRec = nullptr; 
+  } 
+  Available.clear(); 
+  Pending.clear(); 
+  CheckPending = false; 
+  CurrCycle = 0; 
+  CurrMOps = 0; 
+  MinReadyCycle = std::numeric_limits<unsigned>::max(); 
+  ExpectedLatency = 0; 
+  DependentLatency = 0; 
+  RetiredMOps = 0; 
+  MaxExecutedResCount = 0; 
+  ZoneCritResIdx = 0; 
+  IsResourceLimited = false; 
+  ReservedCycles.clear(); 
+  ReservedCyclesIndex.clear(); 
+#ifndef NDEBUG 
+  // Track the maximum number of stall cycles that could arise either from the 
+  // latency of a DAG edge or the number of cycles that a processor resource is 
+  // reserved (SchedBoundary::ReservedCycles). 
+  MaxObservedStall = 0; 
+#endif 
+  // Reserve a zero-count for invalid CritResIdx. 
+  ExecutedResCounts.resize(1); 
+  assert(!ExecutedResCounts[0] && "nonzero count for bad resource"); 
+} 
+ 
+void SchedRemainder:: 
+init(ScheduleDAGMI *DAG, const TargetSchedModel *SchedModel) { 
+  reset(); 
+  if (!SchedModel->hasInstrSchedModel()) 
+    return; 
+  RemainingCounts.resize(SchedModel->getNumProcResourceKinds()); 
+  for (SUnit &SU : DAG->SUnits) { 
+    const MCSchedClassDesc *SC = DAG->getSchedClass(&SU); 
+    RemIssueCount += SchedModel->getNumMicroOps(SU.getInstr(), SC) 
+      * SchedModel->getMicroOpFactor(); 
+    for (TargetSchedModel::ProcResIter 
+           PI = SchedModel->getWriteProcResBegin(SC), 
+           PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) { 
+      unsigned PIdx = PI->ProcResourceIdx; 
+      unsigned Factor = SchedModel->getResourceFactor(PIdx); 
+      RemainingCounts[PIdx] += (Factor * PI->Cycles); 
+    } 
+  } 
+} 
+ 
+void SchedBoundary:: 
+init(ScheduleDAGMI *dag, const TargetSchedModel *smodel, SchedRemainder *rem) { 
+  reset(); 
+  DAG = dag; 
+  SchedModel = smodel; 
+  Rem = rem; 
+  if (SchedModel->hasInstrSchedModel()) { 
+    unsigned ResourceCount = SchedModel->getNumProcResourceKinds(); 
+    ReservedCyclesIndex.resize(ResourceCount); 
+    ExecutedResCounts.resize(ResourceCount); 
+    unsigned NumUnits = 0; 
+ 
+    for (unsigned i = 0; i < ResourceCount; ++i) { 
+      ReservedCyclesIndex[i] = NumUnits; 
+      NumUnits += SchedModel->getProcResource(i)->NumUnits; 
+    } 
+ 
+    ReservedCycles.resize(NumUnits, InvalidCycle); 
+  } 
+} 
+ 
+/// Compute the stall cycles based on this SUnit's ready time. Heuristics treat 
+/// these "soft stalls" differently than the hard stall cycles based on CPU 
+/// resources and computed by checkHazard(). A fully in-order model 
+/// (MicroOpBufferSize==0) will not make use of this since instructions are not 
+/// available for scheduling until they are ready. However, a weaker in-order 
+/// model may use this for heuristics. For example, if a processor has in-order 
+/// behavior when reading certain resources, this may come into play. 
+unsigned SchedBoundary::getLatencyStallCycles(SUnit *SU) { 
+  if (!SU->isUnbuffered) 
+    return 0; 
+ 
+  unsigned ReadyCycle = (isTop() ? SU->TopReadyCycle : SU->BotReadyCycle); 
+  if (ReadyCycle > CurrCycle) 
+    return ReadyCycle - CurrCycle; 
+  return 0; 
+} 
+ 
+/// Compute the next cycle at which the given processor resource unit 
+/// can be scheduled. 
+unsigned SchedBoundary::getNextResourceCycleByInstance(unsigned InstanceIdx, 
+                                                       unsigned Cycles) { 
+  unsigned NextUnreserved = ReservedCycles[InstanceIdx]; 
+  // If this resource has never been used, always return cycle zero. 
+  if (NextUnreserved == InvalidCycle) 
+    return 0; 
+  // For bottom-up scheduling add the cycles needed for the current operation. 
+  if (!isTop()) 
+    NextUnreserved += Cycles; 
+  return NextUnreserved; 
+} 
+ 
+/// Compute the next cycle at which the given processor resource can be 
+/// scheduled.  Returns the next cycle and the index of the processor resource 
+/// instance in the reserved cycles vector. 
+std::pair<unsigned, unsigned> 
+SchedBoundary::getNextResourceCycle(unsigned PIdx, unsigned Cycles) { 
+  unsigned MinNextUnreserved = InvalidCycle; 
+  unsigned InstanceIdx = 0; 
+  unsigned StartIndex = ReservedCyclesIndex[PIdx]; 
+  unsigned NumberOfInstances = SchedModel->getProcResource(PIdx)->NumUnits; 
+  assert(NumberOfInstances > 0 && 
+         "Cannot have zero instances of a ProcResource"); 
+ 
+  for (unsigned I = StartIndex, End = StartIndex + NumberOfInstances; I < End; 
+       ++I) { 
+    unsigned NextUnreserved = getNextResourceCycleByInstance(I, Cycles); 
+    if (MinNextUnreserved > NextUnreserved) { 
+      InstanceIdx = I; 
+      MinNextUnreserved = NextUnreserved; 
+    } 
+  } 
+  return std::make_pair(MinNextUnreserved, InstanceIdx); 
+} 
+ 
+/// Does this SU have a hazard within the current instruction group. 
+/// 
+/// The scheduler supports two modes of hazard recognition. The first is the 
+/// ScheduleHazardRecognizer API. It is a fully general hazard recognizer that 
+/// supports highly complicated in-order reservation tables 
+/// (ScoreboardHazardRecognizer) and arbitrary target-specific logic. 
+/// 
+/// The second is a streamlined mechanism that checks for hazards based on 
+/// simple counters that the scheduler itself maintains. It explicitly checks 
+/// for instruction dispatch limitations, including the number of micro-ops that 
+/// can dispatch per cycle. 
+/// 
+/// TODO: Also check whether the SU must start a new group. 
+bool SchedBoundary::checkHazard(SUnit *SU) { 
+  if (HazardRec->isEnabled() 
+      && HazardRec->getHazardType(SU) != ScheduleHazardRecognizer::NoHazard) { 
+    return true; 
+  } 
+ 
+  unsigned uops = SchedModel->getNumMicroOps(SU->getInstr()); 
+  if ((CurrMOps > 0) && (CurrMOps + uops > SchedModel->getIssueWidth())) { 
+    LLVM_DEBUG(dbgs() << "  SU(" << SU->NodeNum << ") uops=" 
+                      << SchedModel->getNumMicroOps(SU->getInstr()) << '\n'); 
+    return true; 
+  } 
+ 
+  if (CurrMOps > 0 && 
+      ((isTop() && SchedModel->mustBeginGroup(SU->getInstr())) || 
+       (!isTop() && SchedModel->mustEndGroup(SU->getInstr())))) { 
+    LLVM_DEBUG(dbgs() << "  hazard: SU(" << SU->NodeNum << ") must " 
+                      << (isTop() ? "begin" : "end") << " group\n"); 
+    return true; 
+  } 
+ 
+  if (SchedModel->hasInstrSchedModel() && SU->hasReservedResource) { 
+    const MCSchedClassDesc *SC = DAG->getSchedClass(SU); 
+    for (const MCWriteProcResEntry &PE : 
+          make_range(SchedModel->getWriteProcResBegin(SC), 
+                     SchedModel->getWriteProcResEnd(SC))) { 
+      unsigned ResIdx = PE.ProcResourceIdx; 
+      unsigned Cycles = PE.Cycles; 
+      unsigned NRCycle, InstanceIdx; 
+      std::tie(NRCycle, InstanceIdx) = getNextResourceCycle(ResIdx, Cycles); 
+      if (NRCycle > CurrCycle) { 
+#ifndef NDEBUG 
+        MaxObservedStall = std::max(Cycles, MaxObservedStall); 
+#endif 
+        LLVM_DEBUG(dbgs() << "  SU(" << SU->NodeNum << ") " 
+                          << SchedModel->getResourceName(ResIdx) 
+                          << '[' << InstanceIdx - ReservedCyclesIndex[ResIdx]  << ']' 
+                          << "=" << NRCycle << "c\n"); 
+        return true; 
+      } 
+    } 
+  } 
+  return false; 
+} 
+ 
+// Find the unscheduled node in ReadySUs with the highest latency. 
+unsigned SchedBoundary:: 
+findMaxLatency(ArrayRef<SUnit*> ReadySUs) { 
+  SUnit *LateSU = nullptr; 
+  unsigned RemLatency = 0; 
+  for (SUnit *SU : ReadySUs) { 
+    unsigned L = getUnscheduledLatency(SU); 
+    if (L > RemLatency) { 
+      RemLatency = L; 
+      LateSU = SU; 
+    } 
+  } 
+  if (LateSU) { 
+    LLVM_DEBUG(dbgs() << Available.getName() << " RemLatency SU(" 
+                      << LateSU->NodeNum << ") " << RemLatency << "c\n"); 
+  } 
+  return RemLatency; 
+} 
+ 
+// Count resources in this zone and the remaining unscheduled 
+// instruction. Return the max count, scaled. Set OtherCritIdx to the critical 
+// resource index, or zero if the zone is issue limited. 
+unsigned SchedBoundary:: 
+getOtherResourceCount(unsigned &OtherCritIdx) { 
+  OtherCritIdx = 0; 
+  if (!SchedModel->hasInstrSchedModel()) 
+    return 0; 
+ 
+  unsigned OtherCritCount = Rem->RemIssueCount 
+    + (RetiredMOps * SchedModel->getMicroOpFactor()); 
+  LLVM_DEBUG(dbgs() << "  " << Available.getName() << " + Remain MOps: " 
+                    << OtherCritCount / SchedModel->getMicroOpFactor() << '\n'); 
+  for (unsigned PIdx = 1, PEnd = SchedModel->getNumProcResourceKinds(); 
+       PIdx != PEnd; ++PIdx) { 
+    unsigned OtherCount = getResourceCount(PIdx) + Rem->RemainingCounts[PIdx]; 
+    if (OtherCount > OtherCritCount) { 
+      OtherCritCount = OtherCount; 
+      OtherCritIdx = PIdx; 
+    } 
+  } 
+  if (OtherCritIdx) { 
+    LLVM_DEBUG( 
+        dbgs() << "  " << Available.getName() << " + Remain CritRes: " 
+               << OtherCritCount / SchedModel->getResourceFactor(OtherCritIdx) 
+               << " " << SchedModel->getResourceName(OtherCritIdx) << "\n"); 
+  } 
+  return OtherCritCount; 
+} 
+ 
+void SchedBoundary::releaseNode(SUnit *SU, unsigned ReadyCycle, bool InPQueue, 
+                                unsigned Idx) { 
+  assert(SU->getInstr() && "Scheduled SUnit must have instr"); 
+ 
+#ifndef NDEBUG 
+  // ReadyCycle was been bumped up to the CurrCycle when this node was 
+  // scheduled, but CurrCycle may have been eagerly advanced immediately after 
+  // scheduling, so may now be greater than ReadyCycle. 
+  if (ReadyCycle > CurrCycle) 
+    MaxObservedStall = std::max(ReadyCycle - CurrCycle, MaxObservedStall); 
+#endif 
+ 
+  if (ReadyCycle < MinReadyCycle) 
+    MinReadyCycle = ReadyCycle; 
+ 
+  // Check for interlocks first. For the purpose of other heuristics, an 
+  // instruction that cannot issue appears as if it's not in the ReadyQueue. 
+  bool IsBuffered = SchedModel->getMicroOpBufferSize() != 0; 
+  bool HazardDetected = (!IsBuffered && ReadyCycle > CurrCycle) || 
+                        checkHazard(SU) || (Available.size() >= ReadyListLimit); 
+ 
+  if (!HazardDetected) { 
+    Available.push(SU); 
+ 
+    if (InPQueue) 
+      Pending.remove(Pending.begin() + Idx); 
+    return; 
+  } 
+ 
+  if (!InPQueue) 
+    Pending.push(SU); 
+} 
+ 
+/// Move the boundary of scheduled code by one cycle. 
+void SchedBoundary::bumpCycle(unsigned NextCycle) { 
+  if (SchedModel->getMicroOpBufferSize() == 0) { 
+    assert(MinReadyCycle < std::numeric_limits<unsigned>::max() && 
+           "MinReadyCycle uninitialized"); 
+    if (MinReadyCycle > NextCycle) 
+      NextCycle = MinReadyCycle; 
+  } 
+  // Update the current micro-ops, which will issue in the next cycle. 
+  unsigned DecMOps = SchedModel->getIssueWidth() * (NextCycle - CurrCycle); 
+  CurrMOps = (CurrMOps <= DecMOps) ? 0 : CurrMOps - DecMOps; 
+ 
+  // Decrement DependentLatency based on the next cycle. 
+  if ((NextCycle - CurrCycle) > DependentLatency) 
+    DependentLatency = 0; 
+  else 
+    DependentLatency -= (NextCycle - CurrCycle); 
+ 
+  if (!HazardRec->isEnabled()) { 
+    // Bypass HazardRec virtual calls. 
+    CurrCycle = NextCycle; 
+  } else { 
+    // Bypass getHazardType calls in case of long latency. 
+    for (; CurrCycle != NextCycle; ++CurrCycle) { 
+      if (isTop()) 
+        HazardRec->AdvanceCycle(); 
+      else 
+        HazardRec->RecedeCycle(); 
+    } 
+  } 
+  CheckPending = true; 
+  IsResourceLimited = 
+      checkResourceLimit(SchedModel->getLatencyFactor(), getCriticalCount(), 
+                         getScheduledLatency(), true); 
+ 
+  LLVM_DEBUG(dbgs() << "Cycle: " << CurrCycle << ' ' << Available.getName() 
+                    << '\n'); 
+} 
+ 
+void SchedBoundary::incExecutedResources(unsigned PIdx, unsigned Count) { 
+  ExecutedResCounts[PIdx] += Count; 
+  if (ExecutedResCounts[PIdx] > MaxExecutedResCount) 
+    MaxExecutedResCount = ExecutedResCounts[PIdx]; 
+} 
+ 
+/// Add the given processor resource to this scheduled zone. 
+/// 
+/// \param Cycles indicates the number of consecutive (non-pipelined) cycles 
+/// during which this resource is consumed. 
+/// 
+/// \return the next cycle at which the instruction may execute without 
+/// oversubscribing resources. 
+unsigned SchedBoundary:: 
+countResource(unsigned PIdx, unsigned Cycles, unsigned NextCycle) { 
+  unsigned Factor = SchedModel->getResourceFactor(PIdx); 
+  unsigned Count = Factor * Cycles; 
+  LLVM_DEBUG(dbgs() << "  " << SchedModel->getResourceName(PIdx) << " +" 
+                    << Cycles << "x" << Factor << "u\n"); 
+ 
+  // Update Executed resources counts. 
+  incExecutedResources(PIdx, Count); 
+  assert(Rem->RemainingCounts[PIdx] >= Count && "resource double counted"); 
+  Rem->RemainingCounts[PIdx] -= Count; 
+ 
+  // Check if this resource exceeds the current critical resource. If so, it 
+  // becomes the critical resource. 
+  if (ZoneCritResIdx != PIdx && (getResourceCount(PIdx) > getCriticalCount())) { 
+    ZoneCritResIdx = PIdx; 
+    LLVM_DEBUG(dbgs() << "  *** Critical resource " 
+                      << SchedModel->getResourceName(PIdx) << ": " 
+                      << getResourceCount(PIdx) / SchedModel->getLatencyFactor() 
+                      << "c\n"); 
+  } 
+  // For reserved resources, record the highest cycle using the resource. 
+  unsigned NextAvailable, InstanceIdx; 
+  std::tie(NextAvailable, InstanceIdx) = getNextResourceCycle(PIdx, Cycles); 
+  if (NextAvailable > CurrCycle) { 
+    LLVM_DEBUG(dbgs() << "  Resource conflict: " 
+                      << SchedModel->getResourceName(PIdx) 
+                      << '[' << InstanceIdx - ReservedCyclesIndex[PIdx]  << ']' 
+                      << " reserved until @" << NextAvailable << "\n"); 
+  } 
+  return NextAvailable; 
+} 
+ 
+/// Move the boundary of scheduled code by one SUnit. 
+void SchedBoundary::bumpNode(SUnit *SU) { 
+  // Update the reservation table. 
+  if (HazardRec->isEnabled()) { 
+    if (!isTop() && SU->isCall) { 
+      // Calls are scheduled with their preceding instructions. For bottom-up 
+      // scheduling, clear the pipeline state before emitting. 
+      HazardRec->Reset(); 
+    } 
+    HazardRec->EmitInstruction(SU); 
+    // Scheduling an instruction may have made pending instructions available. 
+    CheckPending = true; 
+  } 
+  // checkHazard should prevent scheduling multiple instructions per cycle that 
+  // exceed the issue width. 
+  const MCSchedClassDesc *SC = DAG->getSchedClass(SU); 
+  unsigned IncMOps = SchedModel->getNumMicroOps(SU->getInstr()); 
+  assert( 
+      (CurrMOps == 0 || (CurrMOps + IncMOps) <= SchedModel->getIssueWidth()) && 
+      "Cannot schedule this instruction's MicroOps in the current cycle."); 
+ 
+  unsigned ReadyCycle = (isTop() ? SU->TopReadyCycle : SU->BotReadyCycle); 
+  LLVM_DEBUG(dbgs() << "  Ready @" << ReadyCycle << "c\n"); 
+ 
+  unsigned NextCycle = CurrCycle; 
+  switch (SchedModel->getMicroOpBufferSize()) { 
+  case 0: 
+    assert(ReadyCycle <= CurrCycle && "Broken PendingQueue"); 
+    break; 
+  case 1: 
+    if (ReadyCycle > NextCycle) { 
+      NextCycle = ReadyCycle; 
+      LLVM_DEBUG(dbgs() << "  *** Stall until: " << ReadyCycle << "\n"); 
+    } 
+    break; 
+  default: 
+    // We don't currently model the OOO reorder buffer, so consider all 
+    // scheduled MOps to be "retired". We do loosely model in-order resource 
+    // latency. If this instruction uses an in-order resource, account for any 
+    // likely stall cycles. 
+    if (SU->isUnbuffered && ReadyCycle > NextCycle) 
+      NextCycle = ReadyCycle; 
+    break; 
+  } 
+  RetiredMOps += IncMOps; 
+ 
+  // Update resource counts and critical resource. 
+  if (SchedModel->hasInstrSchedModel()) { 
+    unsigned DecRemIssue = IncMOps * SchedModel->getMicroOpFactor(); 
+    assert(Rem->RemIssueCount >= DecRemIssue && "MOps double counted"); 
+    Rem->RemIssueCount -= DecRemIssue; 
+    if (ZoneCritResIdx) { 
+      // Scale scheduled micro-ops for comparing with the critical resource. 
+      unsigned ScaledMOps = 
+        RetiredMOps * SchedModel->getMicroOpFactor(); 
+ 
+      // If scaled micro-ops are now more than the previous critical resource by 
+      // a full cycle, then micro-ops issue becomes critical. 
+      if ((int)(ScaledMOps - getResourceCount(ZoneCritResIdx)) 
+          >= (int)SchedModel->getLatencyFactor()) { 
+        ZoneCritResIdx = 0; 
+        LLVM_DEBUG(dbgs() << "  *** Critical resource NumMicroOps: " 
+                          << ScaledMOps / SchedModel->getLatencyFactor() 
+                          << "c\n"); 
+      } 
+    } 
+    for (TargetSchedModel::ProcResIter 
+           PI = SchedModel->getWriteProcResBegin(SC), 
+           PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) { 
+      unsigned RCycle = 
+        countResource(PI->ProcResourceIdx, PI->Cycles, NextCycle); 
+      if (RCycle > NextCycle) 
+        NextCycle = RCycle; 
+    } 
+    if (SU->hasReservedResource) { 
+      // For reserved resources, record the highest cycle using the resource. 
+      // For top-down scheduling, this is the cycle in which we schedule this 
+      // instruction plus the number of cycles the operations reserves the 
+      // resource. For bottom-up is it simply the instruction's cycle. 
+      for (TargetSchedModel::ProcResIter 
+             PI = SchedModel->getWriteProcResBegin(SC), 
+             PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) { 
+        unsigned PIdx = PI->ProcResourceIdx; 
+        if (SchedModel->getProcResource(PIdx)->BufferSize == 0) { 
+          unsigned ReservedUntil, InstanceIdx; 
+          std::tie(ReservedUntil, InstanceIdx) = getNextResourceCycle(PIdx, 0); 
+          if (isTop()) { 
+            ReservedCycles[InstanceIdx] = 
+                std::max(ReservedUntil, NextCycle + PI->Cycles); 
+          } else 
+            ReservedCycles[InstanceIdx] = NextCycle; 
+        } 
+      } 
+    } 
+  } 
+  // Update ExpectedLatency and DependentLatency. 
+  unsigned &TopLatency = isTop() ? ExpectedLatency : DependentLatency; 
+  unsigned &BotLatency = isTop() ? DependentLatency : ExpectedLatency; 
+  if (SU->getDepth() > TopLatency) { 
+    TopLatency = SU->getDepth(); 
+    LLVM_DEBUG(dbgs() << "  " << Available.getName() << " TopLatency SU(" 
+                      << SU->NodeNum << ") " << TopLatency << "c\n"); 
+  } 
+  if (SU->getHeight() > BotLatency) { 
+    BotLatency = SU->getHeight(); 
+    LLVM_DEBUG(dbgs() << "  " << Available.getName() << " BotLatency SU(" 
+                      << SU->NodeNum << ") " << BotLatency << "c\n"); 
+  } 
+  // If we stall for any reason, bump the cycle. 
+  if (NextCycle > CurrCycle) 
+    bumpCycle(NextCycle); 
+  else 
+    // After updating ZoneCritResIdx and ExpectedLatency, check if we're 
+    // resource limited. If a stall occurred, bumpCycle does this. 
+    IsResourceLimited = 
+        checkResourceLimit(SchedModel->getLatencyFactor(), getCriticalCount(), 
+                           getScheduledLatency(), true); 
+ 
+  // Update CurrMOps after calling bumpCycle to handle stalls, since bumpCycle 
+  // resets CurrMOps. Loop to handle instructions with more MOps than issue in 
+  // one cycle.  Since we commonly reach the max MOps here, opportunistically 
+  // bump the cycle to avoid uselessly checking everything in the readyQ. 
+  CurrMOps += IncMOps; 
+ 
+  // Bump the cycle count for issue group constraints. 
+  // This must be done after NextCycle has been adjust for all other stalls. 
+  // Calling bumpCycle(X) will reduce CurrMOps by one issue group and set 
+  // currCycle to X. 
+  if ((isTop() &&  SchedModel->mustEndGroup(SU->getInstr())) || 
+      (!isTop() && SchedModel->mustBeginGroup(SU->getInstr()))) { 
+    LLVM_DEBUG(dbgs() << "  Bump cycle to " << (isTop() ? "end" : "begin") 
+                      << " group\n"); 
+    bumpCycle(++NextCycle); 
+  } 
+ 
+  while (CurrMOps >= SchedModel->getIssueWidth()) { 
+    LLVM_DEBUG(dbgs() << "  *** Max MOps " << CurrMOps << " at cycle " 
+                      << CurrCycle << '\n'); 
+    bumpCycle(++NextCycle); 
+  } 
+  LLVM_DEBUG(dumpScheduledState()); 
+} 
+ 
+/// Release pending ready nodes in to the available queue. This makes them 
+/// visible to heuristics. 
+void SchedBoundary::releasePending() { 
+  // If the available queue is empty, it is safe to reset MinReadyCycle. 
+  if (Available.empty()) 
+    MinReadyCycle = std::numeric_limits<unsigned>::max(); 
+ 
+  // Check to see if any of the pending instructions are ready to issue.  If 
+  // so, add them to the available queue. 
+  for (unsigned I = 0, E = Pending.size(); I < E; ++I) { 
+    SUnit *SU = *(Pending.begin() + I); 
+    unsigned ReadyCycle = isTop() ? SU->TopReadyCycle : SU->BotReadyCycle; 
+ 
+    if (ReadyCycle < MinReadyCycle) 
+      MinReadyCycle = ReadyCycle; 
+ 
+    if (Available.size() >= ReadyListLimit) 
+      break; 
+ 
+    releaseNode(SU, ReadyCycle, true, I); 
+    if (E != Pending.size()) { 
+      --I; 
+      --E; 
+    } 
+  } 
+  CheckPending = false; 
+} 
+ 
+/// Remove SU from the ready set for this boundary. 
+void SchedBoundary::removeReady(SUnit *SU) { 
+  if (Available.isInQueue(SU)) 
+    Available.remove(Available.find(SU)); 
+  else { 
+    assert(Pending.isInQueue(SU) && "bad ready count"); 
+    Pending.remove(Pending.find(SU)); 
+  } 
+} 
+ 
+/// If this queue only has one ready candidate, return it. As a side effect, 
+/// defer any nodes that now hit a hazard, and advance the cycle until at least 
+/// one node is ready. If multiple instructions are ready, return NULL. 
+SUnit *SchedBoundary::pickOnlyChoice() { 
+  if (CheckPending) 
+    releasePending(); 
+ 
+  // Defer any ready instrs that now have a hazard. 
+  for (ReadyQueue::iterator I = Available.begin(); I != Available.end();) { 
+    if (checkHazard(*I)) { 
+      Pending.push(*I); 
+      I = Available.remove(I); 
+      continue; 
+    } 
+    ++I; 
+  } 
+  for (unsigned i = 0; Available.empty(); ++i) { 
+//  FIXME: Re-enable assert once PR20057 is resolved. 
+//    assert(i <= (HazardRec->getMaxLookAhead() + MaxObservedStall) && 
+//           "permanent hazard"); 
+    (void)i; 
+    bumpCycle(CurrCycle + 1); 
+    releasePending(); 
+  } 
+ 
+  LLVM_DEBUG(Pending.dump()); 
+  LLVM_DEBUG(Available.dump()); 
+ 
+  if (Available.size() == 1) 
+    return *Available.begin(); 
+  return nullptr; 
+} 
+ 
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 
+// This is useful information to dump after bumpNode. 
+// Note that the Queue contents are more useful before pickNodeFromQueue. 
+LLVM_DUMP_METHOD void SchedBoundary::dumpScheduledState() const { 
+  unsigned ResFactor; 
+  unsigned ResCount; 
+  if (ZoneCritResIdx) { 
+    ResFactor = SchedModel->getResourceFactor(ZoneCritResIdx); 
+    ResCount = getResourceCount(ZoneCritResIdx); 
+  } else { 
+    ResFactor = SchedModel->getMicroOpFactor(); 
+    ResCount = RetiredMOps * ResFactor; 
+  } 
+  unsigned LFactor = SchedModel->getLatencyFactor(); 
+  dbgs() << Available.getName() << " @" << CurrCycle << "c\n" 
+         << "  Retired: " << RetiredMOps; 
+  dbgs() << "\n  Executed: " << getExecutedCount() / LFactor << "c"; 
+  dbgs() << "\n  Critical: " << ResCount / LFactor << "c, " 
+         << ResCount / ResFactor << " " 
+         << SchedModel->getResourceName(ZoneCritResIdx) 
+         << "\n  ExpectedLatency: " << ExpectedLatency << "c\n" 
+         << (IsResourceLimited ? "  - Resource" : "  - Latency") 
+         << " limited.\n"; 
+} 
+#endif 
+ 
+//===----------------------------------------------------------------------===// 
+// GenericScheduler - Generic implementation of MachineSchedStrategy. 
+//===----------------------------------------------------------------------===// 
+ 
+void GenericSchedulerBase::SchedCandidate:: 
+initResourceDelta(const ScheduleDAGMI *DAG, 
+                  const TargetSchedModel *SchedModel) { 
+  if (!Policy.ReduceResIdx && !Policy.DemandResIdx) 
+    return; 
+ 
+  const MCSchedClassDesc *SC = DAG->getSchedClass(SU); 
+  for (TargetSchedModel::ProcResIter 
+         PI = SchedModel->getWriteProcResBegin(SC), 
+         PE = SchedModel->getWriteProcResEnd(SC); PI != PE; ++PI) { 
+    if (PI->ProcResourceIdx == Policy.ReduceResIdx) 
+      ResDelta.CritResources += PI->Cycles; 
+    if (PI->ProcResourceIdx == Policy.DemandResIdx) 
+      ResDelta.DemandedResources += PI->Cycles; 
+  } 
+} 
+ 
+/// Compute remaining latency. We need this both to determine whether the 
+/// overall schedule has become latency-limited and whether the instructions 
+/// outside this zone are resource or latency limited. 
+/// 
+/// The "dependent" latency is updated incrementally during scheduling as the 
+/// max height/depth of scheduled nodes minus the cycles since it was 
+/// scheduled: 
+///   DLat = max (N.depth - (CurrCycle - N.ReadyCycle) for N in Zone 
+/// 
+/// The "independent" latency is the max ready queue depth: 
+///   ILat = max N.depth for N in Available|Pending 
+/// 
+/// RemainingLatency is the greater of independent and dependent latency. 
+/// 
+/// These computations are expensive, especially in DAGs with many edges, so 
+/// only do them if necessary. 
+static unsigned computeRemLatency(SchedBoundary &CurrZone) { 
+  unsigned RemLatency = CurrZone.getDependentLatency(); 
+  RemLatency = std::max(RemLatency, 
+                        CurrZone.findMaxLatency(CurrZone.Available.elements())); 
+  RemLatency = std::max(RemLatency, 
+                        CurrZone.findMaxLatency(CurrZone.Pending.elements())); 
+  return RemLatency; 
+} 
+ 
+/// Returns true if the current cycle plus remaning latency is greater than 
+/// the critical path in the scheduling region. 
+bool GenericSchedulerBase::shouldReduceLatency(const CandPolicy &Policy, 
+                                               SchedBoundary &CurrZone, 
+                                               bool ComputeRemLatency, 
+                                               unsigned &RemLatency) const { 
+  // The current cycle is already greater than the critical path, so we are 
+  // already latency limited and don't need to compute the remaining latency. 
+  if (CurrZone.getCurrCycle() > Rem.CriticalPath) 
+    return true; 
+ 
+  // If we haven't scheduled anything yet, then we aren't latency limited. 
+  if (CurrZone.getCurrCycle() == 0) 
+    return false; 
+ 
+  if (ComputeRemLatency) 
+    RemLatency = computeRemLatency(CurrZone); 
+ 
+  return RemLatency + CurrZone.getCurrCycle() > Rem.CriticalPath; 
+} 
+ 
+/// Set the CandPolicy given a scheduling zone given the current resources and 
+/// latencies inside and outside the zone. 
+void GenericSchedulerBase::setPolicy(CandPolicy &Policy, bool IsPostRA, 
+                                     SchedBoundary &CurrZone, 
+                                     SchedBoundary *OtherZone) { 
+  // Apply preemptive heuristics based on the total latency and resources 
+  // inside and outside this zone. Potential stalls should be considered before 
+  // following this policy. 
+ 
+  // Compute the critical resource outside the zone. 
+  unsigned OtherCritIdx = 0; 
+  unsigned OtherCount = 
+    OtherZone ? OtherZone->getOtherResourceCount(OtherCritIdx) : 0; 
+ 
+  bool OtherResLimited = false; 
+  unsigned RemLatency = 0; 
+  bool RemLatencyComputed = false; 
+  if (SchedModel->hasInstrSchedModel() && OtherCount != 0) { 
+    RemLatency = computeRemLatency(CurrZone); 
+    RemLatencyComputed = true; 
+    OtherResLimited = checkResourceLimit(SchedModel->getLatencyFactor(), 
+                                         OtherCount, RemLatency, false); 
+  } 
+ 
+  // Schedule aggressively for latency in PostRA mode. We don't check for 
+  // acyclic latency during PostRA, and highly out-of-order processors will 
+  // skip PostRA scheduling. 
+  if (!OtherResLimited && 
+      (IsPostRA || shouldReduceLatency(Policy, CurrZone, !RemLatencyComputed, 
+                                       RemLatency))) { 
+    Policy.ReduceLatency |= true; 
+    LLVM_DEBUG(dbgs() << "  " << CurrZone.Available.getName() 
+                      << " RemainingLatency " << RemLatency << " + " 
+                      << CurrZone.getCurrCycle() << "c > CritPath " 
+                      << Rem.CriticalPath << "\n"); 
+  } 
+  // If the same resource is limiting inside and outside the zone, do nothing. 
+  if (CurrZone.getZoneCritResIdx() == OtherCritIdx) 
+    return; 
+ 
+  LLVM_DEBUG(if (CurrZone.isResourceLimited()) { 
+    dbgs() << "  " << CurrZone.Available.getName() << " ResourceLimited: " 
+           << SchedModel->getResourceName(CurrZone.getZoneCritResIdx()) << "\n"; 
+  } if (OtherResLimited) dbgs() 
+                 << "  RemainingLimit: " 
+                 << SchedModel->getResourceName(OtherCritIdx) << "\n"; 
+             if (!CurrZone.isResourceLimited() && !OtherResLimited) dbgs() 
+             << "  Latency limited both directions.\n"); 
+ 
+  if (CurrZone.isResourceLimited() && !Policy.ReduceResIdx) 
+    Policy.ReduceResIdx = CurrZone.getZoneCritResIdx(); 
+ 
+  if (OtherResLimited) 
+    Policy.DemandResIdx = OtherCritIdx; 
+} 
+ 
+#ifndef NDEBUG 
+const char *GenericSchedulerBase::getReasonStr( 
+  GenericSchedulerBase::CandReason Reason) { 
+  switch (Reason) { 
+  case NoCand:         return "NOCAND    "; 
+  case Only1:          return "ONLY1     "; 
+  case PhysReg:        return "PHYS-REG  "; 
+  case RegExcess:      return "REG-EXCESS"; 
+  case RegCritical:    return "REG-CRIT  "; 
+  case Stall:          return "STALL     "; 
+  case Cluster:        return "CLUSTER   "; 
+  case Weak:           return "WEAK      "; 
+  case RegMax:         return "REG-MAX   "; 
+  case ResourceReduce: return "RES-REDUCE"; 
+  case ResourceDemand: return "RES-DEMAND"; 
+  case TopDepthReduce: return "TOP-DEPTH "; 
+  case TopPathReduce:  return "TOP-PATH  "; 
+  case BotHeightReduce:return "BOT-HEIGHT"; 
+  case BotPathReduce:  return "BOT-PATH  "; 
+  case NextDefUse:     return "DEF-USE   "; 
+  case NodeOrder:      return "ORDER     "; 
+  }; 
+  llvm_unreachable("Unknown reason!"); 
+} 
+ 
+void GenericSchedulerBase::traceCandidate(const SchedCandidate &Cand) { 
+  PressureChange P; 
+  unsigned ResIdx = 0; 
+  unsigned Latency = 0; 
+  switch (Cand.Reason) { 
+  default: 
+    break; 
+  case RegExcess: 
+    P = Cand.RPDelta.Excess; 
+    break; 
+  case RegCritical: 
+    P = Cand.RPDelta.CriticalMax; 
+    break; 
+  case RegMax: 
+    P = Cand.RPDelta.CurrentMax; 
+    break; 
+  case ResourceReduce: 
+    ResIdx = Cand.Policy.ReduceResIdx; 
+    break; 
+  case ResourceDemand: 
+    ResIdx = Cand.Policy.DemandResIdx; 
+    break; 
+  case TopDepthReduce: 
+    Latency = Cand.SU->getDepth(); 
+    break; 
+  case TopPathReduce: 
+    Latency = Cand.SU->getHeight(); 
+    break; 
+  case BotHeightReduce: 
+    Latency = Cand.SU->getHeight(); 
+    break; 
+  case BotPathReduce: 
+    Latency = Cand.SU->getDepth(); 
+    break; 
+  } 
+  dbgs() << "  Cand SU(" << Cand.SU->NodeNum << ") " << getReasonStr(Cand.Reason); 
+  if (P.isValid()) 
+    dbgs() << " " << TRI->getRegPressureSetName(P.getPSet()) 
+           << ":" << P.getUnitInc() << " "; 
+  else 
+    dbgs() << "      "; 
+  if (ResIdx) 
+    dbgs() << " " << SchedModel->getProcResource(ResIdx)->Name << " "; 
+  else 
+    dbgs() << "         "; 
+  if (Latency) 
+    dbgs() << " " << Latency << " cycles "; 
+  else 
+    dbgs() << "          "; 
+  dbgs() << '\n'; 
+} 
+#endif 
+ 
+namespace llvm { 
+/// Return true if this heuristic determines order. 
+bool tryLess(int TryVal, int CandVal, 
+             GenericSchedulerBase::SchedCandidate &TryCand, 
+             GenericSchedulerBase::SchedCandidate &Cand, 
+             GenericSchedulerBase::CandReason Reason) { 
+  if (TryVal < CandVal) { 
+    TryCand.Reason = Reason; 
+    return true; 
+  } 
+  if (TryVal > CandVal) { 
+    if (Cand.Reason > Reason) 
+      Cand.Reason = Reason; 
+    return true; 
+  } 
+  return false; 
+} 
+ 
+bool tryGreater(int TryVal, int CandVal, 
+                GenericSchedulerBase::SchedCandidate &TryCand, 
+                GenericSchedulerBase::SchedCandidate &Cand, 
+                GenericSchedulerBase::CandReason Reason) { 
+  if (TryVal > CandVal) { 
+    TryCand.Reason = Reason; 
+    return true; 
+  } 
+  if (TryVal < CandVal) { 
+    if (Cand.Reason > Reason) 
+      Cand.Reason = Reason; 
+    return true; 
+  } 
+  return false; 
+} 
+ 
+bool tryLatency(GenericSchedulerBase::SchedCandidate &TryCand, 
+                GenericSchedulerBase::SchedCandidate &Cand, 
+                SchedBoundary &Zone) { 
+  if (Zone.isTop()) { 
     // Prefer the candidate with the lesser depth, but only if one of them has
     // depth greater than the total latency scheduled so far, otherwise either
     // of them could be scheduled now with no stall.
     if (std::max(TryCand.SU->getDepth(), Cand.SU->getDepth()) >
         Zone.getScheduledLatency()) {
-      if (tryLess(TryCand.SU->getDepth(), Cand.SU->getDepth(),
-                  TryCand, Cand, GenericSchedulerBase::TopDepthReduce))
-        return true;
-    }
-    if (tryGreater(TryCand.SU->getHeight(), Cand.SU->getHeight(),
-                   TryCand, Cand, GenericSchedulerBase::TopPathReduce))
-      return true;
-  } else {
+      if (tryLess(TryCand.SU->getDepth(), Cand.SU->getDepth(), 
+                  TryCand, Cand, GenericSchedulerBase::TopDepthReduce)) 
+        return true; 
+    } 
+    if (tryGreater(TryCand.SU->getHeight(), Cand.SU->getHeight(), 
+                   TryCand, Cand, GenericSchedulerBase::TopPathReduce)) 
+      return true; 
+  } else { 
     // Prefer the candidate with the lesser height, but only if one of them has
     // height greater than the total latency scheduled so far, otherwise either
     // of them could be scheduled now with no stall.
     if (std::max(TryCand.SU->getHeight(), Cand.SU->getHeight()) >
         Zone.getScheduledLatency()) {
-      if (tryLess(TryCand.SU->getHeight(), Cand.SU->getHeight(),
-                  TryCand, Cand, GenericSchedulerBase::BotHeightReduce))
-        return true;
-    }
-    if (tryGreater(TryCand.SU->getDepth(), Cand.SU->getDepth(),
-                   TryCand, Cand, GenericSchedulerBase::BotPathReduce))
-      return true;
-  }
-  return false;
-}
-} // end namespace llvm
-
-static void tracePick(GenericSchedulerBase::CandReason Reason, bool IsTop) {
-  LLVM_DEBUG(dbgs() << "Pick " << (IsTop ? "Top " : "Bot ")
-                    << GenericSchedulerBase::getReasonStr(Reason) << '\n');
-}
-
-static void tracePick(const GenericSchedulerBase::SchedCandidate &Cand) {
-  tracePick(Cand.Reason, Cand.AtTop);
-}
-
-void GenericScheduler::initialize(ScheduleDAGMI *dag) {
-  assert(dag->hasVRegLiveness() &&
-         "(PreRA)GenericScheduler needs vreg liveness");
-  DAG = static_cast<ScheduleDAGMILive*>(dag);
-  SchedModel = DAG->getSchedModel();
-  TRI = DAG->TRI;
-
-  if (RegionPolicy.ComputeDFSResult)
-    DAG->computeDFSResult();
-
-  Rem.init(DAG, SchedModel);
-  Top.init(DAG, SchedModel, &Rem);
-  Bot.init(DAG, SchedModel, &Rem);
-
-  // Initialize resource counts.
-
-  // Initialize the HazardRecognizers. If itineraries don't exist, are empty, or
-  // are disabled, then these HazardRecs will be disabled.
-  const InstrItineraryData *Itin = SchedModel->getInstrItineraries();
-  if (!Top.HazardRec) {
-    Top.HazardRec =
-        DAG->MF.getSubtarget().getInstrInfo()->CreateTargetMIHazardRecognizer(
-            Itin, DAG);
-  }
-  if (!Bot.HazardRec) {
-    Bot.HazardRec =
-        DAG->MF.getSubtarget().getInstrInfo()->CreateTargetMIHazardRecognizer(
-            Itin, DAG);
-  }
-  TopCand.SU = nullptr;
-  BotCand.SU = nullptr;
-}
-
-/// Initialize the per-region scheduling policy.
-void GenericScheduler::initPolicy(MachineBasicBlock::iterator Begin,
-                                  MachineBasicBlock::iterator End,
-                                  unsigned NumRegionInstrs) {
-  const MachineFunction &MF = *Begin->getMF();
-  const TargetLowering *TLI = MF.getSubtarget().getTargetLowering();
-
-  // Avoid setting up the register pressure tracker for small regions to save
-  // compile time. As a rough heuristic, only track pressure when the number of
-  // schedulable instructions exceeds half the integer register file.
-  RegionPolicy.ShouldTrackPressure = true;
-  for (unsigned VT = MVT::i32; VT > (unsigned)MVT::i1; --VT) {
-    MVT::SimpleValueType LegalIntVT = (MVT::SimpleValueType)VT;
-    if (TLI->isTypeLegal(LegalIntVT)) {
-      unsigned NIntRegs = Context->RegClassInfo->getNumAllocatableRegs(
-        TLI->getRegClassFor(LegalIntVT));
-      RegionPolicy.ShouldTrackPressure = NumRegionInstrs > (NIntRegs / 2);
-    }
-  }
-
-  // For generic targets, we default to bottom-up, because it's simpler and more
-  // compile-time optimizations have been implemented in that direction.
-  RegionPolicy.OnlyBottomUp = true;
-
-  // Allow the subtarget to override default policy.
-  MF.getSubtarget().overrideSchedPolicy(RegionPolicy, NumRegionInstrs);
-
-  // After subtarget overrides, apply command line options.
-  if (!EnableRegPressure) {
-    RegionPolicy.ShouldTrackPressure = false;
-    RegionPolicy.ShouldTrackLaneMasks = false;
-  }
-
-  // Check -misched-topdown/bottomup can force or unforce scheduling direction.
-  // e.g. -misched-bottomup=false allows scheduling in both directions.
-  assert((!ForceTopDown || !ForceBottomUp) &&
-         "-misched-topdown incompatible with -misched-bottomup");
-  if (ForceBottomUp.getNumOccurrences() > 0) {
-    RegionPolicy.OnlyBottomUp = ForceBottomUp;
-    if (RegionPolicy.OnlyBottomUp)
-      RegionPolicy.OnlyTopDown = false;
-  }
-  if (ForceTopDown.getNumOccurrences() > 0) {
-    RegionPolicy.OnlyTopDown = ForceTopDown;
-    if (RegionPolicy.OnlyTopDown)
-      RegionPolicy.OnlyBottomUp = false;
-  }
-}
-
-void GenericScheduler::dumpPolicy() const {
-  // Cannot completely remove virtual function even in release mode.
-#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
-  dbgs() << "GenericScheduler RegionPolicy: "
-         << " ShouldTrackPressure=" << RegionPolicy.ShouldTrackPressure
-         << " OnlyTopDown=" << RegionPolicy.OnlyTopDown
-         << " OnlyBottomUp=" << RegionPolicy.OnlyBottomUp
-         << "\n";
-#endif
-}
-
-/// Set IsAcyclicLatencyLimited if the acyclic path is longer than the cyclic
-/// critical path by more cycles than it takes to drain the instruction buffer.
-/// We estimate an upper bounds on in-flight instructions as:
-///
-/// CyclesPerIteration = max( CyclicPath, Loop-Resource-Height )
-/// InFlightIterations = AcyclicPath / CyclesPerIteration
-/// InFlightResources = InFlightIterations * LoopResources
-///
-/// TODO: Check execution resources in addition to IssueCount.
-void GenericScheduler::checkAcyclicLatency() {
-  if (Rem.CyclicCritPath == 0 || Rem.CyclicCritPath >= Rem.CriticalPath)
-    return;
-
-  // Scaled number of cycles per loop iteration.
-  unsigned IterCount =
-    std::max(Rem.CyclicCritPath * SchedModel->getLatencyFactor(),
-             Rem.RemIssueCount);
-  // Scaled acyclic critical path.
-  unsigned AcyclicCount = Rem.CriticalPath * SchedModel->getLatencyFactor();
-  // InFlightCount = (AcyclicPath / IterCycles) * InstrPerLoop
-  unsigned InFlightCount =
-    (AcyclicCount * Rem.RemIssueCount + IterCount-1) / IterCount;
-  unsigned BufferLimit =
-    SchedModel->getMicroOpBufferSize() * SchedModel->getMicroOpFactor();
-
-  Rem.IsAcyclicLatencyLimited = InFlightCount > BufferLimit;
-
-  LLVM_DEBUG(
-      dbgs() << "IssueCycles="
-             << Rem.RemIssueCount / SchedModel->getLatencyFactor() << "c "
-             << "IterCycles=" << IterCount / SchedModel->getLatencyFactor()
-             << "c NumIters=" << (AcyclicCount + IterCount - 1) / IterCount
-             << " InFlight=" << InFlightCount / SchedModel->getMicroOpFactor()
-             << "m BufferLim=" << SchedModel->getMicroOpBufferSize() << "m\n";
-      if (Rem.IsAcyclicLatencyLimited) dbgs() << "  ACYCLIC LATENCY LIMIT\n");
-}
-
-void GenericScheduler::registerRoots() {
-  Rem.CriticalPath = DAG->ExitSU.getDepth();
-
-  // Some roots may not feed into ExitSU. Check all of them in case.
-  for (const SUnit *SU : Bot.Available) {
-    if (SU->getDepth() > Rem.CriticalPath)
-      Rem.CriticalPath = SU->getDepth();
-  }
-  LLVM_DEBUG(dbgs() << "Critical Path(GS-RR ): " << Rem.CriticalPath << '\n');
-  if (DumpCriticalPathLength) {
-    errs() << "Critical Path(GS-RR ): " << Rem.CriticalPath << " \n";
-  }
-
-  if (EnableCyclicPath && SchedModel->getMicroOpBufferSize() > 0) {
-    Rem.CyclicCritPath = DAG->computeCyclicCriticalPath();
-    checkAcyclicLatency();
-  }
-}
-
-namespace llvm {
-bool tryPressure(const PressureChange &TryP,
-                 const PressureChange &CandP,
-                 GenericSchedulerBase::SchedCandidate &TryCand,
-                 GenericSchedulerBase::SchedCandidate &Cand,
-                 GenericSchedulerBase::CandReason Reason,
-                 const TargetRegisterInfo *TRI,
-                 const MachineFunction &MF) {
-  // If one candidate decreases and the other increases, go with it.
-  // Invalid candidates have UnitInc==0.
-  if (tryGreater(TryP.getUnitInc() < 0, CandP.getUnitInc() < 0, TryCand, Cand,
-                 Reason)) {
-    return true;
-  }
-  // Do not compare the magnitude of pressure changes between top and bottom
-  // boundary.
-  if (Cand.AtTop != TryCand.AtTop)
-    return false;
-
-  // If both candidates affect the same set in the same boundary, go with the
-  // smallest increase.
-  unsigned TryPSet = TryP.getPSetOrMax();
-  unsigned CandPSet = CandP.getPSetOrMax();
-  if (TryPSet == CandPSet) {
-    return tryLess(TryP.getUnitInc(), CandP.getUnitInc(), TryCand, Cand,
-                   Reason);
-  }
-
-  int TryRank = TryP.isValid() ? TRI->getRegPressureSetScore(MF, TryPSet) :
-                                 std::numeric_limits<int>::max();
-
-  int CandRank = CandP.isValid() ? TRI->getRegPressureSetScore(MF, CandPSet) :
-                                   std::numeric_limits<int>::max();
-
-  // If the candidates are decreasing pressure, reverse priority.
-  if (TryP.getUnitInc() < 0)
-    std::swap(TryRank, CandRank);
-  return tryGreater(TryRank, CandRank, TryCand, Cand, Reason);
-}
-
-unsigned getWeakLeft(const SUnit *SU, bool isTop) {
-  return (isTop) ? SU->WeakPredsLeft : SU->WeakSuccsLeft;
-}
-
-/// Minimize physical register live ranges. Regalloc wants them adjacent to
-/// their physreg def/use.
-///
-/// FIXME: This is an unnecessary check on the critical path. Most are root/leaf
-/// copies which can be prescheduled. The rest (e.g. x86 MUL) could be bundled
-/// with the operation that produces or consumes the physreg. We'll do this when
-/// regalloc has support for parallel copies.
-int biasPhysReg(const SUnit *SU, bool isTop) {
-  const MachineInstr *MI = SU->getInstr();
-
-  if (MI->isCopy()) {
-    unsigned ScheduledOper = isTop ? 1 : 0;
-    unsigned UnscheduledOper = isTop ? 0 : 1;
-    // If we have already scheduled the physreg produce/consumer, immediately
-    // schedule the copy.
-    if (Register::isPhysicalRegister(MI->getOperand(ScheduledOper).getReg()))
-      return 1;
-    // If the physreg is at the boundary, defer it. Otherwise schedule it
-    // immediately to free the dependent. We can hoist the copy later.
-    bool AtBoundary = isTop ? !SU->NumSuccsLeft : !SU->NumPredsLeft;
-    if (Register::isPhysicalRegister(MI->getOperand(UnscheduledOper).getReg()))
-      return AtBoundary ? -1 : 1;
-  }
-
-  if (MI->isMoveImmediate()) {
-    // If we have a move immediate and all successors have been assigned, bias
-    // towards scheduling this later. Make sure all register defs are to
-    // physical registers.
-    bool DoBias = true;
-    for (const MachineOperand &Op : MI->defs()) {
-      if (Op.isReg() && !Register::isPhysicalRegister(Op.getReg())) {
-        DoBias = false;
-        break;
-      }
-    }
-
-    if (DoBias)
-      return isTop ? -1 : 1;
-  }
-
-  return 0;
-}
-} // end namespace llvm
-
-void GenericScheduler::initCandidate(SchedCandidate &Cand, SUnit *SU,
-                                     bool AtTop,
-                                     const RegPressureTracker &RPTracker,
-                                     RegPressureTracker &TempTracker) {
-  Cand.SU = SU;
-  Cand.AtTop = AtTop;
-  if (DAG->isTrackingPressure()) {
-    if (AtTop) {
-      TempTracker.getMaxDownwardPressureDelta(
-        Cand.SU->getInstr(),
-        Cand.RPDelta,
-        DAG->getRegionCriticalPSets(),
-        DAG->getRegPressure().MaxSetPressure);
-    } else {
-      if (VerifyScheduling) {
-        TempTracker.getMaxUpwardPressureDelta(
-          Cand.SU->getInstr(),
-          &DAG->getPressureDiff(Cand.SU),
-          Cand.RPDelta,
-          DAG->getRegionCriticalPSets(),
-          DAG->getRegPressure().MaxSetPressure);
-      } else {
-        RPTracker.getUpwardPressureDelta(
-          Cand.SU->getInstr(),
-          DAG->getPressureDiff(Cand.SU),
-          Cand.RPDelta,
-          DAG->getRegionCriticalPSets(),
-          DAG->getRegPressure().MaxSetPressure);
-      }
-    }
-  }
-  LLVM_DEBUG(if (Cand.RPDelta.Excess.isValid()) dbgs()
-             << "  Try  SU(" << Cand.SU->NodeNum << ") "
-             << TRI->getRegPressureSetName(Cand.RPDelta.Excess.getPSet()) << ":"
-             << Cand.RPDelta.Excess.getUnitInc() << "\n");
-}
-
-/// Apply a set of heuristics to a new candidate. Heuristics are currently
-/// hierarchical. This may be more efficient than a graduated cost model because
-/// we don't need to evaluate all aspects of the model for each node in the
-/// queue. But it's really done to make the heuristics easier to debug and
-/// statistically analyze.
-///
-/// \param Cand provides the policy and current best candidate.
-/// \param TryCand refers to the next SUnit candidate, otherwise uninitialized.
-/// \param Zone describes the scheduled zone that we are extending, or nullptr
-//              if Cand is from a different zone than TryCand.
-void GenericScheduler::tryCandidate(SchedCandidate &Cand,
-                                    SchedCandidate &TryCand,
-                                    SchedBoundary *Zone) const {
-  // Initialize the candidate if needed.
-  if (!Cand.isValid()) {
-    TryCand.Reason = NodeOrder;
-    return;
-  }
-
-  // Bias PhysReg Defs and copies to their uses and defined respectively.
-  if (tryGreater(biasPhysReg(TryCand.SU, TryCand.AtTop),
-                 biasPhysReg(Cand.SU, Cand.AtTop), TryCand, Cand, PhysReg))
-    return;
-
-  // Avoid exceeding the target's limit.
-  if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.Excess,
-                                               Cand.RPDelta.Excess,
-                                               TryCand, Cand, RegExcess, TRI,
-                                               DAG->MF))
-    return;
-
-  // Avoid increasing the max critical pressure in the scheduled region.
-  if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.CriticalMax,
-                                               Cand.RPDelta.CriticalMax,
-                                               TryCand, Cand, RegCritical, TRI,
-                                               DAG->MF))
-    return;
-
-  // We only compare a subset of features when comparing nodes between
-  // Top and Bottom boundary. Some properties are simply incomparable, in many
-  // other instances we should only override the other boundary if something
-  // is a clear good pick on one boundary. Skip heuristics that are more
-  // "tie-breaking" in nature.
-  bool SameBoundary = Zone != nullptr;
-  if (SameBoundary) {
-    // For loops that are acyclic path limited, aggressively schedule for
-    // latency. Within an single cycle, whenever CurrMOps > 0, allow normal
-    // heuristics to take precedence.
-    if (Rem.IsAcyclicLatencyLimited && !Zone->getCurrMOps() &&
-        tryLatency(TryCand, Cand, *Zone))
-      return;
-
-    // Prioritize instructions that read unbuffered resources by stall cycles.
-    if (tryLess(Zone->getLatencyStallCycles(TryCand.SU),
-                Zone->getLatencyStallCycles(Cand.SU), TryCand, Cand, Stall))
-      return;
-  }
-
-  // Keep clustered nodes together to encourage downstream peephole
-  // optimizations which may reduce resource requirements.
-  //
-  // This is a best effort to set things up for a post-RA pass. Optimizations
-  // like generating loads of multiple registers should ideally be done within
-  // the scheduler pass by combining the loads during DAG postprocessing.
-  const SUnit *CandNextClusterSU =
-    Cand.AtTop ? DAG->getNextClusterSucc() : DAG->getNextClusterPred();
-  const SUnit *TryCandNextClusterSU =
-    TryCand.AtTop ? DAG->getNextClusterSucc() : DAG->getNextClusterPred();
-  if (tryGreater(TryCand.SU == TryCandNextClusterSU,
-                 Cand.SU == CandNextClusterSU,
-                 TryCand, Cand, Cluster))
-    return;
-
-  if (SameBoundary) {
-    // Weak edges are for clustering and other constraints.
-    if (tryLess(getWeakLeft(TryCand.SU, TryCand.AtTop),
-                getWeakLeft(Cand.SU, Cand.AtTop),
-                TryCand, Cand, Weak))
-      return;
-  }
-
-  // Avoid increasing the max pressure of the entire region.
-  if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.CurrentMax,
-                                               Cand.RPDelta.CurrentMax,
-                                               TryCand, Cand, RegMax, TRI,
-                                               DAG->MF))
-    return;
-
-  if (SameBoundary) {
-    // Avoid critical resource consumption and balance the schedule.
-    TryCand.initResourceDelta(DAG, SchedModel);
-    if (tryLess(TryCand.ResDelta.CritResources, Cand.ResDelta.CritResources,
-                TryCand, Cand, ResourceReduce))
-      return;
-    if (tryGreater(TryCand.ResDelta.DemandedResources,
-                   Cand.ResDelta.DemandedResources,
-                   TryCand, Cand, ResourceDemand))
-      return;
-
-    // Avoid serializing long latency dependence chains.
-    // For acyclic path limited loops, latency was already checked above.
-    if (!RegionPolicy.DisableLatencyHeuristic && TryCand.Policy.ReduceLatency &&
-        !Rem.IsAcyclicLatencyLimited && tryLatency(TryCand, Cand, *Zone))
-      return;
-
-    // Fall through to original instruction order.
-    if ((Zone->isTop() && TryCand.SU->NodeNum < Cand.SU->NodeNum)
-        || (!Zone->isTop() && TryCand.SU->NodeNum > Cand.SU->NodeNum)) {
-      TryCand.Reason = NodeOrder;
-    }
-  }
-}
-
-/// Pick the best candidate from the queue.
-///
-/// TODO: getMaxPressureDelta results can be mostly cached for each SUnit during
-/// DAG building. To adjust for the current scheduling location we need to
-/// maintain the number of vreg uses remaining to be top-scheduled.
-void GenericScheduler::pickNodeFromQueue(SchedBoundary &Zone,
-                                         const CandPolicy &ZonePolicy,
-                                         const RegPressureTracker &RPTracker,
-                                         SchedCandidate &Cand) {
-  // getMaxPressureDelta temporarily modifies the tracker.
-  RegPressureTracker &TempTracker = const_cast<RegPressureTracker&>(RPTracker);
-
-  ReadyQueue &Q = Zone.Available;
-  for (SUnit *SU : Q) {
-
-    SchedCandidate TryCand(ZonePolicy);
-    initCandidate(TryCand, SU, Zone.isTop(), RPTracker, TempTracker);
-    // Pass SchedBoundary only when comparing nodes from the same boundary.
-    SchedBoundary *ZoneArg = Cand.AtTop == TryCand.AtTop ? &Zone : nullptr;
-    tryCandidate(Cand, TryCand, ZoneArg);
-    if (TryCand.Reason != NoCand) {
-      // Initialize resource delta if needed in case future heuristics query it.
-      if (TryCand.ResDelta == SchedResourceDelta())
-        TryCand.initResourceDelta(DAG, SchedModel);
-      Cand.setBest(TryCand);
-      LLVM_DEBUG(traceCandidate(Cand));
-    }
-  }
-}
-
-/// Pick the best candidate node from either the top or bottom queue.
-SUnit *GenericScheduler::pickNodeBidirectional(bool &IsTopNode) {
-  // Schedule as far as possible in the direction of no choice. This is most
-  // efficient, but also provides the best heuristics for CriticalPSets.
-  if (SUnit *SU = Bot.pickOnlyChoice()) {
-    IsTopNode = false;
-    tracePick(Only1, false);
-    return SU;
-  }
-  if (SUnit *SU = Top.pickOnlyChoice()) {
-    IsTopNode = true;
-    tracePick(Only1, true);
-    return SU;
-  }
-  // Set the bottom-up policy based on the state of the current bottom zone and
-  // the instructions outside the zone, including the top zone.
-  CandPolicy BotPolicy;
-  setPolicy(BotPolicy, /*IsPostRA=*/false, Bot, &Top);
-  // Set the top-down policy based on the state of the current top zone and
-  // the instructions outside the zone, including the bottom zone.
-  CandPolicy TopPolicy;
-  setPolicy(TopPolicy, /*IsPostRA=*/false, Top, &Bot);
-
-  // See if BotCand is still valid (because we previously scheduled from Top).
-  LLVM_DEBUG(dbgs() << "Picking from Bot:\n");
-  if (!BotCand.isValid() || BotCand.SU->isScheduled ||
-      BotCand.Policy != BotPolicy) {
-    BotCand.reset(CandPolicy());
-    pickNodeFromQueue(Bot, BotPolicy, DAG->getBotRPTracker(), BotCand);
-    assert(BotCand.Reason != NoCand && "failed to find the first candidate");
-  } else {
-    LLVM_DEBUG(traceCandidate(BotCand));
-#ifndef NDEBUG
-    if (VerifyScheduling) {
-      SchedCandidate TCand;
-      TCand.reset(CandPolicy());
-      pickNodeFromQueue(Bot, BotPolicy, DAG->getBotRPTracker(), TCand);
-      assert(TCand.SU == BotCand.SU &&
-             "Last pick result should correspond to re-picking right now");
-    }
-#endif
-  }
-
-  // Check if the top Q has a better candidate.
-  LLVM_DEBUG(dbgs() << "Picking from Top:\n");
-  if (!TopCand.isValid() || TopCand.SU->isScheduled ||
-      TopCand.Policy != TopPolicy) {
-    TopCand.reset(CandPolicy());
-    pickNodeFromQueue(Top, TopPolicy, DAG->getTopRPTracker(), TopCand);
-    assert(TopCand.Reason != NoCand && "failed to find the first candidate");
-  } else {
-    LLVM_DEBUG(traceCandidate(TopCand));
-#ifndef NDEBUG
-    if (VerifyScheduling) {
-      SchedCandidate TCand;
-      TCand.reset(CandPolicy());
-      pickNodeFromQueue(Top, TopPolicy, DAG->getTopRPTracker(), TCand);
-      assert(TCand.SU == TopCand.SU &&
-           "Last pick result should correspond to re-picking right now");
-    }
-#endif
-  }
-
-  // Pick best from BotCand and TopCand.
-  assert(BotCand.isValid());
-  assert(TopCand.isValid());
-  SchedCandidate Cand = BotCand;
-  TopCand.Reason = NoCand;
-  tryCandidate(Cand, TopCand, nullptr);
-  if (TopCand.Reason != NoCand) {
-    Cand.setBest(TopCand);
-    LLVM_DEBUG(traceCandidate(Cand));
-  }
-
-  IsTopNode = Cand.AtTop;
-  tracePick(Cand);
-  return Cand.SU;
-}
-
-/// Pick the best node to balance the schedule. Implements MachineSchedStrategy.
-SUnit *GenericScheduler::pickNode(bool &IsTopNode) {
-  if (DAG->top() == DAG->bottom()) {
-    assert(Top.Available.empty() && Top.Pending.empty() &&
-           Bot.Available.empty() && Bot.Pending.empty() && "ReadyQ garbage");
-    return nullptr;
-  }
-  SUnit *SU;
-  do {
-    if (RegionPolicy.OnlyTopDown) {
-      SU = Top.pickOnlyChoice();
-      if (!SU) {
-        CandPolicy NoPolicy;
-        TopCand.reset(NoPolicy);
-        pickNodeFromQueue(Top, NoPolicy, DAG->getTopRPTracker(), TopCand);
-        assert(TopCand.Reason != NoCand && "failed to find a candidate");
-        tracePick(TopCand);
-        SU = TopCand.SU;
-      }
-      IsTopNode = true;
-    } else if (RegionPolicy.OnlyBottomUp) {
-      SU = Bot.pickOnlyChoice();
-      if (!SU) {
-        CandPolicy NoPolicy;
-        BotCand.reset(NoPolicy);
-        pickNodeFromQueue(Bot, NoPolicy, DAG->getBotRPTracker(), BotCand);
-        assert(BotCand.Reason != NoCand && "failed to find a candidate");
-        tracePick(BotCand);
-        SU = BotCand.SU;
-      }
-      IsTopNode = false;
-    } else {
-      SU = pickNodeBidirectional(IsTopNode);
-    }
-  } while (SU->isScheduled);
-
-  if (SU->isTopReady())
-    Top.removeReady(SU);
-  if (SU->isBottomReady())
-    Bot.removeReady(SU);
-
-  LLVM_DEBUG(dbgs() << "Scheduling SU(" << SU->NodeNum << ") "
-                    << *SU->getInstr());
-  return SU;
-}
-
-void GenericScheduler::reschedulePhysReg(SUnit *SU, bool isTop) {
-  MachineBasicBlock::iterator InsertPos = SU->getInstr();
-  if (!isTop)
-    ++InsertPos;
-  SmallVectorImpl<SDep> &Deps = isTop ? SU->Preds : SU->Succs;
-
-  // Find already scheduled copies with a single physreg dependence and move
-  // them just above the scheduled instruction.
-  for (SDep &Dep : Deps) {
-    if (Dep.getKind() != SDep::Data ||
-        !Register::isPhysicalRegister(Dep.getReg()))
-      continue;
-    SUnit *DepSU = Dep.getSUnit();
-    if (isTop ? DepSU->Succs.size() > 1 : DepSU->Preds.size() > 1)
-      continue;
-    MachineInstr *Copy = DepSU->getInstr();
-    if (!Copy->isCopy() && !Copy->isMoveImmediate())
-      continue;
-    LLVM_DEBUG(dbgs() << "  Rescheduling physreg copy ";
-               DAG->dumpNode(*Dep.getSUnit()));
-    DAG->moveInstruction(Copy, InsertPos);
-  }
-}
-
-/// Update the scheduler's state after scheduling a node. This is the same node
-/// that was just returned by pickNode(). However, ScheduleDAGMILive needs to
-/// update it's state based on the current cycle before MachineSchedStrategy
-/// does.
-///
-/// FIXME: Eventually, we may bundle physreg copies rather than rescheduling
-/// them here. See comments in biasPhysReg.
-void GenericScheduler::schedNode(SUnit *SU, bool IsTopNode) {
-  if (IsTopNode) {
-    SU->TopReadyCycle = std::max(SU->TopReadyCycle, Top.getCurrCycle());
-    Top.bumpNode(SU);
-    if (SU->hasPhysRegUses)
-      reschedulePhysReg(SU, true);
-  } else {
-    SU->BotReadyCycle = std::max(SU->BotReadyCycle, Bot.getCurrCycle());
-    Bot.bumpNode(SU);
-    if (SU->hasPhysRegDefs)
-      reschedulePhysReg(SU, false);
-  }
-}
-
-/// Create the standard converging machine scheduler. This will be used as the
-/// default scheduler if the target does not set a default.
-ScheduleDAGMILive *llvm::createGenericSchedLive(MachineSchedContext *C) {
-  ScheduleDAGMILive *DAG =
-      new ScheduleDAGMILive(C, std::make_unique<GenericScheduler>(C));
-  // Register DAG post-processors.
-  //
-  // FIXME: extend the mutation API to allow earlier mutations to instantiate
-  // data and pass it to later mutations. Have a single mutation that gathers
-  // the interesting nodes in one pass.
-  DAG->addMutation(createCopyConstrainDAGMutation(DAG->TII, DAG->TRI));
-  return DAG;
-}
-
+      if (tryLess(TryCand.SU->getHeight(), Cand.SU->getHeight(), 
+                  TryCand, Cand, GenericSchedulerBase::BotHeightReduce)) 
+        return true; 
+    } 
+    if (tryGreater(TryCand.SU->getDepth(), Cand.SU->getDepth(), 
+                   TryCand, Cand, GenericSchedulerBase::BotPathReduce)) 
+      return true; 
+  } 
+  return false; 
+} 
+} // end namespace llvm 
+ 
+static void tracePick(GenericSchedulerBase::CandReason Reason, bool IsTop) { 
+  LLVM_DEBUG(dbgs() << "Pick " << (IsTop ? "Top " : "Bot ") 
+                    << GenericSchedulerBase::getReasonStr(Reason) << '\n'); 
+} 
+ 
+static void tracePick(const GenericSchedulerBase::SchedCandidate &Cand) { 
+  tracePick(Cand.Reason, Cand.AtTop); 
+} 
+ 
+void GenericScheduler::initialize(ScheduleDAGMI *dag) { 
+  assert(dag->hasVRegLiveness() && 
+         "(PreRA)GenericScheduler needs vreg liveness"); 
+  DAG = static_cast<ScheduleDAGMILive*>(dag); 
+  SchedModel = DAG->getSchedModel(); 
+  TRI = DAG->TRI; 
+ 
+  if (RegionPolicy.ComputeDFSResult) 
+    DAG->computeDFSResult(); 
+ 
+  Rem.init(DAG, SchedModel); 
+  Top.init(DAG, SchedModel, &Rem); 
+  Bot.init(DAG, SchedModel, &Rem); 
+ 
+  // Initialize resource counts. 
+ 
+  // Initialize the HazardRecognizers. If itineraries don't exist, are empty, or 
+  // are disabled, then these HazardRecs will be disabled. 
+  const InstrItineraryData *Itin = SchedModel->getInstrItineraries(); 
+  if (!Top.HazardRec) { 
+    Top.HazardRec = 
+        DAG->MF.getSubtarget().getInstrInfo()->CreateTargetMIHazardRecognizer( 
+            Itin, DAG); 
+  } 
+  if (!Bot.HazardRec) { 
+    Bot.HazardRec = 
+        DAG->MF.getSubtarget().getInstrInfo()->CreateTargetMIHazardRecognizer( 
+            Itin, DAG); 
+  } 
+  TopCand.SU = nullptr; 
+  BotCand.SU = nullptr; 
+} 
+ 
+/// Initialize the per-region scheduling policy. 
+void GenericScheduler::initPolicy(MachineBasicBlock::iterator Begin, 
+                                  MachineBasicBlock::iterator End, 
+                                  unsigned NumRegionInstrs) { 
+  const MachineFunction &MF = *Begin->getMF(); 
+  const TargetLowering *TLI = MF.getSubtarget().getTargetLowering(); 
+ 
+  // Avoid setting up the register pressure tracker for small regions to save 
+  // compile time. As a rough heuristic, only track pressure when the number of 
+  // schedulable instructions exceeds half the integer register file. 
+  RegionPolicy.ShouldTrackPressure = true; 
+  for (unsigned VT = MVT::i32; VT > (unsigned)MVT::i1; --VT) { 
+    MVT::SimpleValueType LegalIntVT = (MVT::SimpleValueType)VT; 
+    if (TLI->isTypeLegal(LegalIntVT)) { 
+      unsigned NIntRegs = Context->RegClassInfo->getNumAllocatableRegs( 
+        TLI->getRegClassFor(LegalIntVT)); 
+      RegionPolicy.ShouldTrackPressure = NumRegionInstrs > (NIntRegs / 2); 
+    } 
+  } 
+ 
+  // For generic targets, we default to bottom-up, because it's simpler and more 
+  // compile-time optimizations have been implemented in that direction. 
+  RegionPolicy.OnlyBottomUp = true; 
+ 
+  // Allow the subtarget to override default policy. 
+  MF.getSubtarget().overrideSchedPolicy(RegionPolicy, NumRegionInstrs); 
+ 
+  // After subtarget overrides, apply command line options. 
+  if (!EnableRegPressure) { 
+    RegionPolicy.ShouldTrackPressure = false; 
+    RegionPolicy.ShouldTrackLaneMasks = false; 
+  } 
+ 
+  // Check -misched-topdown/bottomup can force or unforce scheduling direction. 
+  // e.g. -misched-bottomup=false allows scheduling in both directions. 
+  assert((!ForceTopDown || !ForceBottomUp) && 
+         "-misched-topdown incompatible with -misched-bottomup"); 
+  if (ForceBottomUp.getNumOccurrences() > 0) { 
+    RegionPolicy.OnlyBottomUp = ForceBottomUp; 
+    if (RegionPolicy.OnlyBottomUp) 
+      RegionPolicy.OnlyTopDown = false; 
+  } 
+  if (ForceTopDown.getNumOccurrences() > 0) { 
+    RegionPolicy.OnlyTopDown = ForceTopDown; 
+    if (RegionPolicy.OnlyTopDown) 
+      RegionPolicy.OnlyBottomUp = false; 
+  } 
+} 
+ 
+void GenericScheduler::dumpPolicy() const { 
+  // Cannot completely remove virtual function even in release mode. 
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 
+  dbgs() << "GenericScheduler RegionPolicy: " 
+         << " ShouldTrackPressure=" << RegionPolicy.ShouldTrackPressure 
+         << " OnlyTopDown=" << RegionPolicy.OnlyTopDown 
+         << " OnlyBottomUp=" << RegionPolicy.OnlyBottomUp 
+         << "\n"; 
+#endif 
+} 
+ 
+/// Set IsAcyclicLatencyLimited if the acyclic path is longer than the cyclic 
+/// critical path by more cycles than it takes to drain the instruction buffer. 
+/// We estimate an upper bounds on in-flight instructions as: 
+/// 
+/// CyclesPerIteration = max( CyclicPath, Loop-Resource-Height ) 
+/// InFlightIterations = AcyclicPath / CyclesPerIteration 
+/// InFlightResources = InFlightIterations * LoopResources 
+/// 
+/// TODO: Check execution resources in addition to IssueCount. 
+void GenericScheduler::checkAcyclicLatency() { 
+  if (Rem.CyclicCritPath == 0 || Rem.CyclicCritPath >= Rem.CriticalPath) 
+    return; 
+ 
+  // Scaled number of cycles per loop iteration. 
+  unsigned IterCount = 
+    std::max(Rem.CyclicCritPath * SchedModel->getLatencyFactor(), 
+             Rem.RemIssueCount); 
+  // Scaled acyclic critical path. 
+  unsigned AcyclicCount = Rem.CriticalPath * SchedModel->getLatencyFactor(); 
+  // InFlightCount = (AcyclicPath / IterCycles) * InstrPerLoop 
+  unsigned InFlightCount = 
+    (AcyclicCount * Rem.RemIssueCount + IterCount-1) / IterCount; 
+  unsigned BufferLimit = 
+    SchedModel->getMicroOpBufferSize() * SchedModel->getMicroOpFactor(); 
+ 
+  Rem.IsAcyclicLatencyLimited = InFlightCount > BufferLimit; 
+ 
+  LLVM_DEBUG( 
+      dbgs() << "IssueCycles=" 
+             << Rem.RemIssueCount / SchedModel->getLatencyFactor() << "c " 
+             << "IterCycles=" << IterCount / SchedModel->getLatencyFactor() 
+             << "c NumIters=" << (AcyclicCount + IterCount - 1) / IterCount 
+             << " InFlight=" << InFlightCount / SchedModel->getMicroOpFactor() 
+             << "m BufferLim=" << SchedModel->getMicroOpBufferSize() << "m\n"; 
+      if (Rem.IsAcyclicLatencyLimited) dbgs() << "  ACYCLIC LATENCY LIMIT\n"); 
+} 
+ 
+void GenericScheduler::registerRoots() { 
+  Rem.CriticalPath = DAG->ExitSU.getDepth(); 
+ 
+  // Some roots may not feed into ExitSU. Check all of them in case. 
+  for (const SUnit *SU : Bot.Available) { 
+    if (SU->getDepth() > Rem.CriticalPath) 
+      Rem.CriticalPath = SU->getDepth(); 
+  } 
+  LLVM_DEBUG(dbgs() << "Critical Path(GS-RR ): " << Rem.CriticalPath << '\n'); 
+  if (DumpCriticalPathLength) { 
+    errs() << "Critical Path(GS-RR ): " << Rem.CriticalPath << " \n"; 
+  } 
+ 
+  if (EnableCyclicPath && SchedModel->getMicroOpBufferSize() > 0) { 
+    Rem.CyclicCritPath = DAG->computeCyclicCriticalPath(); 
+    checkAcyclicLatency(); 
+  } 
+} 
+ 
+namespace llvm { 
+bool tryPressure(const PressureChange &TryP, 
+                 const PressureChange &CandP, 
+                 GenericSchedulerBase::SchedCandidate &TryCand, 
+                 GenericSchedulerBase::SchedCandidate &Cand, 
+                 GenericSchedulerBase::CandReason Reason, 
+                 const TargetRegisterInfo *TRI, 
+                 const MachineFunction &MF) { 
+  // If one candidate decreases and the other increases, go with it. 
+  // Invalid candidates have UnitInc==0. 
+  if (tryGreater(TryP.getUnitInc() < 0, CandP.getUnitInc() < 0, TryCand, Cand, 
+                 Reason)) { 
+    return true; 
+  } 
+  // Do not compare the magnitude of pressure changes between top and bottom 
+  // boundary. 
+  if (Cand.AtTop != TryCand.AtTop) 
+    return false; 
+ 
+  // If both candidates affect the same set in the same boundary, go with the 
+  // smallest increase. 
+  unsigned TryPSet = TryP.getPSetOrMax(); 
+  unsigned CandPSet = CandP.getPSetOrMax(); 
+  if (TryPSet == CandPSet) { 
+    return tryLess(TryP.getUnitInc(), CandP.getUnitInc(), TryCand, Cand, 
+                   Reason); 
+  } 
+ 
+  int TryRank = TryP.isValid() ? TRI->getRegPressureSetScore(MF, TryPSet) : 
+                                 std::numeric_limits<int>::max(); 
+ 
+  int CandRank = CandP.isValid() ? TRI->getRegPressureSetScore(MF, CandPSet) : 
+                                   std::numeric_limits<int>::max(); 
+ 
+  // If the candidates are decreasing pressure, reverse priority. 
+  if (TryP.getUnitInc() < 0) 
+    std::swap(TryRank, CandRank); 
+  return tryGreater(TryRank, CandRank, TryCand, Cand, Reason); 
+} 
+ 
+unsigned getWeakLeft(const SUnit *SU, bool isTop) { 
+  return (isTop) ? SU->WeakPredsLeft : SU->WeakSuccsLeft; 
+} 
+ 
+/// Minimize physical register live ranges. Regalloc wants them adjacent to 
+/// their physreg def/use. 
+/// 
+/// FIXME: This is an unnecessary check on the critical path. Most are root/leaf 
+/// copies which can be prescheduled. The rest (e.g. x86 MUL) could be bundled 
+/// with the operation that produces or consumes the physreg. We'll do this when 
+/// regalloc has support for parallel copies. 
+int biasPhysReg(const SUnit *SU, bool isTop) { 
+  const MachineInstr *MI = SU->getInstr(); 
+ 
+  if (MI->isCopy()) { 
+    unsigned ScheduledOper = isTop ? 1 : 0; 
+    unsigned UnscheduledOper = isTop ? 0 : 1; 
+    // If we have already scheduled the physreg produce/consumer, immediately 
+    // schedule the copy. 
+    if (Register::isPhysicalRegister(MI->getOperand(ScheduledOper).getReg())) 
+      return 1; 
+    // If the physreg is at the boundary, defer it. Otherwise schedule it 
+    // immediately to free the dependent. We can hoist the copy later. 
+    bool AtBoundary = isTop ? !SU->NumSuccsLeft : !SU->NumPredsLeft; 
+    if (Register::isPhysicalRegister(MI->getOperand(UnscheduledOper).getReg())) 
+      return AtBoundary ? -1 : 1; 
+  } 
+ 
+  if (MI->isMoveImmediate()) { 
+    // If we have a move immediate and all successors have been assigned, bias 
+    // towards scheduling this later. Make sure all register defs are to 
+    // physical registers. 
+    bool DoBias = true; 
+    for (const MachineOperand &Op : MI->defs()) { 
+      if (Op.isReg() && !Register::isPhysicalRegister(Op.getReg())) { 
+        DoBias = false; 
+        break; 
+      } 
+    } 
+ 
+    if (DoBias) 
+      return isTop ? -1 : 1; 
+  } 
+ 
+  return 0; 
+} 
+} // end namespace llvm 
+ 
+void GenericScheduler::initCandidate(SchedCandidate &Cand, SUnit *SU, 
+                                     bool AtTop, 
+                                     const RegPressureTracker &RPTracker, 
+                                     RegPressureTracker &TempTracker) { 
+  Cand.SU = SU; 
+  Cand.AtTop = AtTop; 
+  if (DAG->isTrackingPressure()) { 
+    if (AtTop) { 
+      TempTracker.getMaxDownwardPressureDelta( 
+        Cand.SU->getInstr(), 
+        Cand.RPDelta, 
+        DAG->getRegionCriticalPSets(), 
+        DAG->getRegPressure().MaxSetPressure); 
+    } else { 
+      if (VerifyScheduling) { 
+        TempTracker.getMaxUpwardPressureDelta( 
+          Cand.SU->getInstr(), 
+          &DAG->getPressureDiff(Cand.SU), 
+          Cand.RPDelta, 
+          DAG->getRegionCriticalPSets(), 
+          DAG->getRegPressure().MaxSetPressure); 
+      } else { 
+        RPTracker.getUpwardPressureDelta( 
+          Cand.SU->getInstr(), 
+          DAG->getPressureDiff(Cand.SU), 
+          Cand.RPDelta, 
+          DAG->getRegionCriticalPSets(), 
+          DAG->getRegPressure().MaxSetPressure); 
+      } 
+    } 
+  } 
+  LLVM_DEBUG(if (Cand.RPDelta.Excess.isValid()) dbgs() 
+             << "  Try  SU(" << Cand.SU->NodeNum << ") " 
+             << TRI->getRegPressureSetName(Cand.RPDelta.Excess.getPSet()) << ":" 
+             << Cand.RPDelta.Excess.getUnitInc() << "\n"); 
+} 
+ 
+/// Apply a set of heuristics to a new candidate. Heuristics are currently 
+/// hierarchical. This may be more efficient than a graduated cost model because 
+/// we don't need to evaluate all aspects of the model for each node in the 
+/// queue. But it's really done to make the heuristics easier to debug and 
+/// statistically analyze. 
+/// 
+/// \param Cand provides the policy and current best candidate. 
+/// \param TryCand refers to the next SUnit candidate, otherwise uninitialized. 
+/// \param Zone describes the scheduled zone that we are extending, or nullptr 
+//              if Cand is from a different zone than TryCand. 
+void GenericScheduler::tryCandidate(SchedCandidate &Cand, 
+                                    SchedCandidate &TryCand, 
+                                    SchedBoundary *Zone) const { 
+  // Initialize the candidate if needed. 
+  if (!Cand.isValid()) { 
+    TryCand.Reason = NodeOrder; 
+    return; 
+  } 
+ 
+  // Bias PhysReg Defs and copies to their uses and defined respectively. 
+  if (tryGreater(biasPhysReg(TryCand.SU, TryCand.AtTop), 
+                 biasPhysReg(Cand.SU, Cand.AtTop), TryCand, Cand, PhysReg)) 
+    return; 
+ 
+  // Avoid exceeding the target's limit. 
+  if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.Excess, 
+                                               Cand.RPDelta.Excess, 
+                                               TryCand, Cand, RegExcess, TRI, 
+                                               DAG->MF)) 
+    return; 
+ 
+  // Avoid increasing the max critical pressure in the scheduled region. 
+  if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.CriticalMax, 
+                                               Cand.RPDelta.CriticalMax, 
+                                               TryCand, Cand, RegCritical, TRI, 
+                                               DAG->MF)) 
+    return; 
+ 
+  // We only compare a subset of features when comparing nodes between 
+  // Top and Bottom boundary. Some properties are simply incomparable, in many 
+  // other instances we should only override the other boundary if something 
+  // is a clear good pick on one boundary. Skip heuristics that are more 
+  // "tie-breaking" in nature. 
+  bool SameBoundary = Zone != nullptr; 
+  if (SameBoundary) { 
+    // For loops that are acyclic path limited, aggressively schedule for 
+    // latency. Within an single cycle, whenever CurrMOps > 0, allow normal 
+    // heuristics to take precedence. 
+    if (Rem.IsAcyclicLatencyLimited && !Zone->getCurrMOps() && 
+        tryLatency(TryCand, Cand, *Zone)) 
+      return; 
+ 
+    // Prioritize instructions that read unbuffered resources by stall cycles. 
+    if (tryLess(Zone->getLatencyStallCycles(TryCand.SU), 
+                Zone->getLatencyStallCycles(Cand.SU), TryCand, Cand, Stall)) 
+      return; 
+  } 
+ 
+  // Keep clustered nodes together to encourage downstream peephole 
+  // optimizations which may reduce resource requirements. 
+  // 
+  // This is a best effort to set things up for a post-RA pass. Optimizations 
+  // like generating loads of multiple registers should ideally be done within 
+  // the scheduler pass by combining the loads during DAG postprocessing. 
+  const SUnit *CandNextClusterSU = 
+    Cand.AtTop ? DAG->getNextClusterSucc() : DAG->getNextClusterPred(); 
+  const SUnit *TryCandNextClusterSU = 
+    TryCand.AtTop ? DAG->getNextClusterSucc() : DAG->getNextClusterPred(); 
+  if (tryGreater(TryCand.SU == TryCandNextClusterSU, 
+                 Cand.SU == CandNextClusterSU, 
+                 TryCand, Cand, Cluster)) 
+    return; 
+ 
+  if (SameBoundary) { 
+    // Weak edges are for clustering and other constraints. 
+    if (tryLess(getWeakLeft(TryCand.SU, TryCand.AtTop), 
+                getWeakLeft(Cand.SU, Cand.AtTop), 
+                TryCand, Cand, Weak)) 
+      return; 
+  } 
+ 
+  // Avoid increasing the max pressure of the entire region. 
+  if (DAG->isTrackingPressure() && tryPressure(TryCand.RPDelta.CurrentMax, 
+                                               Cand.RPDelta.CurrentMax, 
+                                               TryCand, Cand, RegMax, TRI, 
+                                               DAG->MF)) 
+    return; 
+ 
+  if (SameBoundary) { 
+    // Avoid critical resource consumption and balance the schedule. 
+    TryCand.initResourceDelta(DAG, SchedModel); 
+    if (tryLess(TryCand.ResDelta.CritResources, Cand.ResDelta.CritResources, 
+                TryCand, Cand, ResourceReduce)) 
+      return; 
+    if (tryGreater(TryCand.ResDelta.DemandedResources, 
+                   Cand.ResDelta.DemandedResources, 
+                   TryCand, Cand, ResourceDemand)) 
+      return; 
+ 
+    // Avoid serializing long latency dependence chains. 
+    // For acyclic path limited loops, latency was already checked above. 
+    if (!RegionPolicy.DisableLatencyHeuristic && TryCand.Policy.ReduceLatency && 
+        !Rem.IsAcyclicLatencyLimited && tryLatency(TryCand, Cand, *Zone)) 
+      return; 
+ 
+    // Fall through to original instruction order. 
+    if ((Zone->isTop() && TryCand.SU->NodeNum < Cand.SU->NodeNum) 
+        || (!Zone->isTop() && TryCand.SU->NodeNum > Cand.SU->NodeNum)) { 
+      TryCand.Reason = NodeOrder; 
+    } 
+  } 
+} 
+ 
+/// Pick the best candidate from the queue. 
+/// 
+/// TODO: getMaxPressureDelta results can be mostly cached for each SUnit during 
+/// DAG building. To adjust for the current scheduling location we need to 
+/// maintain the number of vreg uses remaining to be top-scheduled. 
+void GenericScheduler::pickNodeFromQueue(SchedBoundary &Zone, 
+                                         const CandPolicy &ZonePolicy, 
+                                         const RegPressureTracker &RPTracker, 
+                                         SchedCandidate &Cand) { 
+  // getMaxPressureDelta temporarily modifies the tracker. 
+  RegPressureTracker &TempTracker = const_cast<RegPressureTracker&>(RPTracker); 
+ 
+  ReadyQueue &Q = Zone.Available; 
+  for (SUnit *SU : Q) { 
+ 
+    SchedCandidate TryCand(ZonePolicy); 
+    initCandidate(TryCand, SU, Zone.isTop(), RPTracker, TempTracker); 
+    // Pass SchedBoundary only when comparing nodes from the same boundary. 
+    SchedBoundary *ZoneArg = Cand.AtTop == TryCand.AtTop ? &Zone : nullptr; 
+    tryCandidate(Cand, TryCand, ZoneArg); 
+    if (TryCand.Reason != NoCand) { 
+      // Initialize resource delta if needed in case future heuristics query it. 
+      if (TryCand.ResDelta == SchedResourceDelta()) 
+        TryCand.initResourceDelta(DAG, SchedModel); 
+      Cand.setBest(TryCand); 
+      LLVM_DEBUG(traceCandidate(Cand)); 
+    } 
+  } 
+} 
+ 
+/// Pick the best candidate node from either the top or bottom queue. 
+SUnit *GenericScheduler::pickNodeBidirectional(bool &IsTopNode) { 
+  // Schedule as far as possible in the direction of no choice. This is most 
+  // efficient, but also provides the best heuristics for CriticalPSets. 
+  if (SUnit *SU = Bot.pickOnlyChoice()) { 
+    IsTopNode = false; 
+    tracePick(Only1, false); 
+    return SU; 
+  } 
+  if (SUnit *SU = Top.pickOnlyChoice()) { 
+    IsTopNode = true; 
+    tracePick(Only1, true); 
+    return SU; 
+  } 
+  // Set the bottom-up policy based on the state of the current bottom zone and 
+  // the instructions outside the zone, including the top zone. 
+  CandPolicy BotPolicy; 
+  setPolicy(BotPolicy, /*IsPostRA=*/false, Bot, &Top); 
+  // Set the top-down policy based on the state of the current top zone and 
+  // the instructions outside the zone, including the bottom zone. 
+  CandPolicy TopPolicy; 
+  setPolicy(TopPolicy, /*IsPostRA=*/false, Top, &Bot); 
+ 
+  // See if BotCand is still valid (because we previously scheduled from Top). 
+  LLVM_DEBUG(dbgs() << "Picking from Bot:\n"); 
+  if (!BotCand.isValid() || BotCand.SU->isScheduled || 
+      BotCand.Policy != BotPolicy) { 
+    BotCand.reset(CandPolicy()); 
+    pickNodeFromQueue(Bot, BotPolicy, DAG->getBotRPTracker(), BotCand); 
+    assert(BotCand.Reason != NoCand && "failed to find the first candidate"); 
+  } else { 
+    LLVM_DEBUG(traceCandidate(BotCand)); 
+#ifndef NDEBUG 
+    if (VerifyScheduling) { 
+      SchedCandidate TCand; 
+      TCand.reset(CandPolicy()); 
+      pickNodeFromQueue(Bot, BotPolicy, DAG->getBotRPTracker(), TCand); 
+      assert(TCand.SU == BotCand.SU && 
+             "Last pick result should correspond to re-picking right now"); 
+    } 
+#endif 
+  } 
+ 
+  // Check if the top Q has a better candidate. 
+  LLVM_DEBUG(dbgs() << "Picking from Top:\n"); 
+  if (!TopCand.isValid() || TopCand.SU->isScheduled || 
+      TopCand.Policy != TopPolicy) { 
+    TopCand.reset(CandPolicy()); 
+    pickNodeFromQueue(Top, TopPolicy, DAG->getTopRPTracker(), TopCand); 
+    assert(TopCand.Reason != NoCand && "failed to find the first candidate"); 
+  } else { 
+    LLVM_DEBUG(traceCandidate(TopCand)); 
+#ifndef NDEBUG 
+    if (VerifyScheduling) { 
+      SchedCandidate TCand; 
+      TCand.reset(CandPolicy()); 
+      pickNodeFromQueue(Top, TopPolicy, DAG->getTopRPTracker(), TCand); 
+      assert(TCand.SU == TopCand.SU && 
+           "Last pick result should correspond to re-picking right now"); 
+    } 
+#endif 
+  } 
+ 
+  // Pick best from BotCand and TopCand. 
+  assert(BotCand.isValid()); 
+  assert(TopCand.isValid()); 
+  SchedCandidate Cand = BotCand; 
+  TopCand.Reason = NoCand; 
+  tryCandidate(Cand, TopCand, nullptr); 
+  if (TopCand.Reason != NoCand) { 
+    Cand.setBest(TopCand); 
+    LLVM_DEBUG(traceCandidate(Cand)); 
+  } 
+ 
+  IsTopNode = Cand.AtTop; 
+  tracePick(Cand); 
+  return Cand.SU; 
+} 
+ 
+/// Pick the best node to balance the schedule. Implements MachineSchedStrategy. 
+SUnit *GenericScheduler::pickNode(bool &IsTopNode) { 
+  if (DAG->top() == DAG->bottom()) { 
+    assert(Top.Available.empty() && Top.Pending.empty() && 
+           Bot.Available.empty() && Bot.Pending.empty() && "ReadyQ garbage"); 
+    return nullptr; 
+  } 
+  SUnit *SU; 
+  do { 
+    if (RegionPolicy.OnlyTopDown) { 
+      SU = Top.pickOnlyChoice(); 
+      if (!SU) { 
+        CandPolicy NoPolicy; 
+        TopCand.reset(NoPolicy); 
+        pickNodeFromQueue(Top, NoPolicy, DAG->getTopRPTracker(), TopCand); 
+        assert(TopCand.Reason != NoCand && "failed to find a candidate"); 
+        tracePick(TopCand); 
+        SU = TopCand.SU; 
+      } 
+      IsTopNode = true; 
+    } else if (RegionPolicy.OnlyBottomUp) { 
+      SU = Bot.pickOnlyChoice(); 
+      if (!SU) { 
+        CandPolicy NoPolicy; 
+        BotCand.reset(NoPolicy); 
+        pickNodeFromQueue(Bot, NoPolicy, DAG->getBotRPTracker(), BotCand); 
+        assert(BotCand.Reason != NoCand && "failed to find a candidate"); 
+        tracePick(BotCand); 
+        SU = BotCand.SU; 
+      } 
+      IsTopNode = false; 
+    } else { 
+      SU = pickNodeBidirectional(IsTopNode); 
+    } 
+  } while (SU->isScheduled); 
+ 
+  if (SU->isTopReady()) 
+    Top.removeReady(SU); 
+  if (SU->isBottomReady()) 
+    Bot.removeReady(SU); 
+ 
+  LLVM_DEBUG(dbgs() << "Scheduling SU(" << SU->NodeNum << ") " 
+                    << *SU->getInstr()); 
+  return SU; 
+} 
+ 
+void GenericScheduler::reschedulePhysReg(SUnit *SU, bool isTop) { 
+  MachineBasicBlock::iterator InsertPos = SU->getInstr(); 
+  if (!isTop) 
+    ++InsertPos; 
+  SmallVectorImpl<SDep> &Deps = isTop ? SU->Preds : SU->Succs; 
+ 
+  // Find already scheduled copies with a single physreg dependence and move 
+  // them just above the scheduled instruction. 
+  for (SDep &Dep : Deps) { 
+    if (Dep.getKind() != SDep::Data || 
+        !Register::isPhysicalRegister(Dep.getReg())) 
+      continue; 
+    SUnit *DepSU = Dep.getSUnit(); 
+    if (isTop ? DepSU->Succs.size() > 1 : DepSU->Preds.size() > 1) 
+      continue; 
+    MachineInstr *Copy = DepSU->getInstr(); 
+    if (!Copy->isCopy() && !Copy->isMoveImmediate()) 
+      continue; 
+    LLVM_DEBUG(dbgs() << "  Rescheduling physreg copy "; 
+               DAG->dumpNode(*Dep.getSUnit())); 
+    DAG->moveInstruction(Copy, InsertPos); 
+  } 
+} 
+ 
+/// Update the scheduler's state after scheduling a node. This is the same node 
+/// that was just returned by pickNode(). However, ScheduleDAGMILive needs to 
+/// update it's state based on the current cycle before MachineSchedStrategy 
+/// does. 
+/// 
+/// FIXME: Eventually, we may bundle physreg copies rather than rescheduling 
+/// them here. See comments in biasPhysReg. 
+void GenericScheduler::schedNode(SUnit *SU, bool IsTopNode) { 
+  if (IsTopNode) { 
+    SU->TopReadyCycle = std::max(SU->TopReadyCycle, Top.getCurrCycle()); 
+    Top.bumpNode(SU); 
+    if (SU->hasPhysRegUses) 
+      reschedulePhysReg(SU, true); 
+  } else { 
+    SU->BotReadyCycle = std::max(SU->BotReadyCycle, Bot.getCurrCycle()); 
+    Bot.bumpNode(SU); 
+    if (SU->hasPhysRegDefs) 
+      reschedulePhysReg(SU, false); 
+  } 
+} 
+ 
+/// Create the standard converging machine scheduler. This will be used as the 
+/// default scheduler if the target does not set a default. 
+ScheduleDAGMILive *llvm::createGenericSchedLive(MachineSchedContext *C) { 
+  ScheduleDAGMILive *DAG = 
+      new ScheduleDAGMILive(C, std::make_unique<GenericScheduler>(C)); 
+  // Register DAG post-processors. 
+  // 
+  // FIXME: extend the mutation API to allow earlier mutations to instantiate 
+  // data and pass it to later mutations. Have a single mutation that gathers 
+  // the interesting nodes in one pass. 
+  DAG->addMutation(createCopyConstrainDAGMutation(DAG->TII, DAG->TRI)); 
+  return DAG; 
+} 
+ 
 static ScheduleDAGInstrs *createConvergingSched(MachineSchedContext *C) {
-  return createGenericSchedLive(C);
-}
-
-static MachineSchedRegistry
-GenericSchedRegistry("converge", "Standard converging scheduler.",
+  return createGenericSchedLive(C); 
+} 
+ 
+static MachineSchedRegistry 
+GenericSchedRegistry("converge", "Standard converging scheduler.", 
                      createConvergingSched);
-
-//===----------------------------------------------------------------------===//
-// PostGenericScheduler - Generic PostRA implementation of MachineSchedStrategy.
-//===----------------------------------------------------------------------===//
-
-void PostGenericScheduler::initialize(ScheduleDAGMI *Dag) {
-  DAG = Dag;
-  SchedModel = DAG->getSchedModel();
-  TRI = DAG->TRI;
-
-  Rem.init(DAG, SchedModel);
-  Top.init(DAG, SchedModel, &Rem);
-  BotRoots.clear();
-
-  // Initialize the HazardRecognizers. If itineraries don't exist, are empty,
-  // or are disabled, then these HazardRecs will be disabled.
-  const InstrItineraryData *Itin = SchedModel->getInstrItineraries();
-  if (!Top.HazardRec) {
-    Top.HazardRec =
-        DAG->MF.getSubtarget().getInstrInfo()->CreateTargetMIHazardRecognizer(
-            Itin, DAG);
-  }
-}
-
-void PostGenericScheduler::registerRoots() {
-  Rem.CriticalPath = DAG->ExitSU.getDepth();
-
-  // Some roots may not feed into ExitSU. Check all of them in case.
-  for (const SUnit *SU : BotRoots) {
-    if (SU->getDepth() > Rem.CriticalPath)
-      Rem.CriticalPath = SU->getDepth();
-  }
-  LLVM_DEBUG(dbgs() << "Critical Path: (PGS-RR) " << Rem.CriticalPath << '\n');
-  if (DumpCriticalPathLength) {
-    errs() << "Critical Path(PGS-RR ): " << Rem.CriticalPath << " \n";
-  }
-}
-
-/// Apply a set of heuristics to a new candidate for PostRA scheduling.
-///
-/// \param Cand provides the policy and current best candidate.
-/// \param TryCand refers to the next SUnit candidate, otherwise uninitialized.
-void PostGenericScheduler::tryCandidate(SchedCandidate &Cand,
-                                        SchedCandidate &TryCand) {
-  // Initialize the candidate if needed.
-  if (!Cand.isValid()) {
-    TryCand.Reason = NodeOrder;
-    return;
-  }
-
-  // Prioritize instructions that read unbuffered resources by stall cycles.
-  if (tryLess(Top.getLatencyStallCycles(TryCand.SU),
-              Top.getLatencyStallCycles(Cand.SU), TryCand, Cand, Stall))
-    return;
-
-  // Keep clustered nodes together.
-  if (tryGreater(TryCand.SU == DAG->getNextClusterSucc(),
-                 Cand.SU == DAG->getNextClusterSucc(),
-                 TryCand, Cand, Cluster))
-    return;
-
-  // Avoid critical resource consumption and balance the schedule.
-  if (tryLess(TryCand.ResDelta.CritResources, Cand.ResDelta.CritResources,
-              TryCand, Cand, ResourceReduce))
-    return;
-  if (tryGreater(TryCand.ResDelta.DemandedResources,
-                 Cand.ResDelta.DemandedResources,
-                 TryCand, Cand, ResourceDemand))
-    return;
-
-  // Avoid serializing long latency dependence chains.
-  if (Cand.Policy.ReduceLatency && tryLatency(TryCand, Cand, Top)) {
-    return;
-  }
-
-  // Fall through to original instruction order.
-  if (TryCand.SU->NodeNum < Cand.SU->NodeNum)
-    TryCand.Reason = NodeOrder;
-}
-
-void PostGenericScheduler::pickNodeFromQueue(SchedCandidate &Cand) {
-  ReadyQueue &Q = Top.Available;
-  for (SUnit *SU : Q) {
-    SchedCandidate TryCand(Cand.Policy);
-    TryCand.SU = SU;
-    TryCand.AtTop = true;
-    TryCand.initResourceDelta(DAG, SchedModel);
-    tryCandidate(Cand, TryCand);
-    if (TryCand.Reason != NoCand) {
-      Cand.setBest(TryCand);
-      LLVM_DEBUG(traceCandidate(Cand));
-    }
-  }
-}
-
-/// Pick the next node to schedule.
-SUnit *PostGenericScheduler::pickNode(bool &IsTopNode) {
-  if (DAG->top() == DAG->bottom()) {
-    assert(Top.Available.empty() && Top.Pending.empty() && "ReadyQ garbage");
-    return nullptr;
-  }
-  SUnit *SU;
-  do {
-    SU = Top.pickOnlyChoice();
-    if (SU) {
-      tracePick(Only1, true);
-    } else {
-      CandPolicy NoPolicy;
-      SchedCandidate TopCand(NoPolicy);
-      // Set the top-down policy based on the state of the current top zone and
-      // the instructions outside the zone, including the bottom zone.
-      setPolicy(TopCand.Policy, /*IsPostRA=*/true, Top, nullptr);
-      pickNodeFromQueue(TopCand);
-      assert(TopCand.Reason != NoCand && "failed to find a candidate");
-      tracePick(TopCand);
-      SU = TopCand.SU;
-    }
-  } while (SU->isScheduled);
-
-  IsTopNode = true;
-  Top.removeReady(SU);
-
-  LLVM_DEBUG(dbgs() << "Scheduling SU(" << SU->NodeNum << ") "
-                    << *SU->getInstr());
-  return SU;
-}
-
-/// Called after ScheduleDAGMI has scheduled an instruction and updated
-/// scheduled/remaining flags in the DAG nodes.
-void PostGenericScheduler::schedNode(SUnit *SU, bool IsTopNode) {
-  SU->TopReadyCycle = std::max(SU->TopReadyCycle, Top.getCurrCycle());
-  Top.bumpNode(SU);
-}
-
-ScheduleDAGMI *llvm::createGenericSchedPostRA(MachineSchedContext *C) {
-  return new ScheduleDAGMI(C, std::make_unique<PostGenericScheduler>(C),
-                           /*RemoveKillFlags=*/true);
-}
-
-//===----------------------------------------------------------------------===//
-// ILP Scheduler. Currently for experimental analysis of heuristics.
-//===----------------------------------------------------------------------===//
-
-namespace {
-
-/// Order nodes by the ILP metric.
-struct ILPOrder {
-  const SchedDFSResult *DFSResult = nullptr;
-  const BitVector *ScheduledTrees = nullptr;
-  bool MaximizeILP;
-
-  ILPOrder(bool MaxILP) : MaximizeILP(MaxILP) {}
-
-  /// Apply a less-than relation on node priority.
-  ///
-  /// (Return true if A comes after B in the Q.)
-  bool operator()(const SUnit *A, const SUnit *B) const {
-    unsigned SchedTreeA = DFSResult->getSubtreeID(A);
-    unsigned SchedTreeB = DFSResult->getSubtreeID(B);
-    if (SchedTreeA != SchedTreeB) {
-      // Unscheduled trees have lower priority.
-      if (ScheduledTrees->test(SchedTreeA) != ScheduledTrees->test(SchedTreeB))
-        return ScheduledTrees->test(SchedTreeB);
-
-      // Trees with shallower connections have have lower priority.
-      if (DFSResult->getSubtreeLevel(SchedTreeA)
-          != DFSResult->getSubtreeLevel(SchedTreeB)) {
-        return DFSResult->getSubtreeLevel(SchedTreeA)
-          < DFSResult->getSubtreeLevel(SchedTreeB);
-      }
-    }
-    if (MaximizeILP)
-      return DFSResult->getILP(A) < DFSResult->getILP(B);
-    else
-      return DFSResult->getILP(A) > DFSResult->getILP(B);
-  }
-};
-
-/// Schedule based on the ILP metric.
-class ILPScheduler : public MachineSchedStrategy {
-  ScheduleDAGMILive *DAG = nullptr;
-  ILPOrder Cmp;
-
-  std::vector<SUnit*> ReadyQ;
-
-public:
-  ILPScheduler(bool MaximizeILP) : Cmp(MaximizeILP) {}
-
-  void initialize(ScheduleDAGMI *dag) override {
-    assert(dag->hasVRegLiveness() && "ILPScheduler needs vreg liveness");
-    DAG = static_cast<ScheduleDAGMILive*>(dag);
-    DAG->computeDFSResult();
-    Cmp.DFSResult = DAG->getDFSResult();
-    Cmp.ScheduledTrees = &DAG->getScheduledTrees();
-    ReadyQ.clear();
-  }
-
-  void registerRoots() override {
-    // Restore the heap in ReadyQ with the updated DFS results.
-    std::make_heap(ReadyQ.begin(), ReadyQ.end(), Cmp);
-  }
-
-  /// Implement MachineSchedStrategy interface.
-  /// -----------------------------------------
-
-  /// Callback to select the highest priority node from the ready Q.
-  SUnit *pickNode(bool &IsTopNode) override {
-    if (ReadyQ.empty()) return nullptr;
-    std::pop_heap(ReadyQ.begin(), ReadyQ.end(), Cmp);
-    SUnit *SU = ReadyQ.back();
-    ReadyQ.pop_back();
-    IsTopNode = false;
-    LLVM_DEBUG(dbgs() << "Pick node "
-                      << "SU(" << SU->NodeNum << ") "
-                      << " ILP: " << DAG->getDFSResult()->getILP(SU)
-                      << " Tree: " << DAG->getDFSResult()->getSubtreeID(SU)
-                      << " @"
-                      << DAG->getDFSResult()->getSubtreeLevel(
-                             DAG->getDFSResult()->getSubtreeID(SU))
-                      << '\n'
-                      << "Scheduling " << *SU->getInstr());
-    return SU;
-  }
-
-  /// Scheduler callback to notify that a new subtree is scheduled.
-  void scheduleTree(unsigned SubtreeID) override {
-    std::make_heap(ReadyQ.begin(), ReadyQ.end(), Cmp);
-  }
-
-  /// Callback after a node is scheduled. Mark a newly scheduled tree, notify
-  /// DFSResults, and resort the priority Q.
-  void schedNode(SUnit *SU, bool IsTopNode) override {
-    assert(!IsTopNode && "SchedDFSResult needs bottom-up");
-  }
-
-  void releaseTopNode(SUnit *) override { /*only called for top roots*/ }
-
-  void releaseBottomNode(SUnit *SU) override {
-    ReadyQ.push_back(SU);
-    std::push_heap(ReadyQ.begin(), ReadyQ.end(), Cmp);
-  }
-};
-
-} // end anonymous namespace
-
-static ScheduleDAGInstrs *createILPMaxScheduler(MachineSchedContext *C) {
-  return new ScheduleDAGMILive(C, std::make_unique<ILPScheduler>(true));
-}
-static ScheduleDAGInstrs *createILPMinScheduler(MachineSchedContext *C) {
-  return new ScheduleDAGMILive(C, std::make_unique<ILPScheduler>(false));
-}
-
-static MachineSchedRegistry ILPMaxRegistry(
-  "ilpmax", "Schedule bottom-up for max ILP", createILPMaxScheduler);
-static MachineSchedRegistry ILPMinRegistry(
-  "ilpmin", "Schedule bottom-up for min ILP", createILPMinScheduler);
-
-//===----------------------------------------------------------------------===//
-// Machine Instruction Shuffler for Correctness Testing
-//===----------------------------------------------------------------------===//
-
-#ifndef NDEBUG
-namespace {
-
-/// Apply a less-than relation on the node order, which corresponds to the
-/// instruction order prior to scheduling. IsReverse implements greater-than.
-template<bool IsReverse>
-struct SUnitOrder {
-  bool operator()(SUnit *A, SUnit *B) const {
-    if (IsReverse)
-      return A->NodeNum > B->NodeNum;
-    else
-      return A->NodeNum < B->NodeNum;
-  }
-};
-
-/// Reorder instructions as much as possible.
-class InstructionShuffler : public MachineSchedStrategy {
-  bool IsAlternating;
-  bool IsTopDown;
-
-  // Using a less-than relation (SUnitOrder<false>) for the TopQ priority
-  // gives nodes with a higher number higher priority causing the latest
-  // instructions to be scheduled first.
-  PriorityQueue<SUnit*, std::vector<SUnit*>, SUnitOrder<false>>
-    TopQ;
-
-  // When scheduling bottom-up, use greater-than as the queue priority.
-  PriorityQueue<SUnit*, std::vector<SUnit*>, SUnitOrder<true>>
-    BottomQ;
-
-public:
-  InstructionShuffler(bool alternate, bool topdown)
-    : IsAlternating(alternate), IsTopDown(topdown) {}
-
-  void initialize(ScheduleDAGMI*) override {
-    TopQ.clear();
-    BottomQ.clear();
-  }
-
-  /// Implement MachineSchedStrategy interface.
-  /// -----------------------------------------
-
-  SUnit *pickNode(bool &IsTopNode) override {
-    SUnit *SU;
-    if (IsTopDown) {
-      do {
-        if (TopQ.empty()) return nullptr;
-        SU = TopQ.top();
-        TopQ.pop();
-      } while (SU->isScheduled);
-      IsTopNode = true;
-    } else {
-      do {
-        if (BottomQ.empty()) return nullptr;
-        SU = BottomQ.top();
-        BottomQ.pop();
-      } while (SU->isScheduled);
-      IsTopNode = false;
-    }
-    if (IsAlternating)
-      IsTopDown = !IsTopDown;
-    return SU;
-  }
-
-  void schedNode(SUnit *SU, bool IsTopNode) override {}
-
-  void releaseTopNode(SUnit *SU) override {
-    TopQ.push(SU);
-  }
-  void releaseBottomNode(SUnit *SU) override {
-    BottomQ.push(SU);
-  }
-};
-
-} // end anonymous namespace
-
-static ScheduleDAGInstrs *createInstructionShuffler(MachineSchedContext *C) {
-  bool Alternate = !ForceTopDown && !ForceBottomUp;
-  bool TopDown = !ForceBottomUp;
-  assert((TopDown || !ForceTopDown) &&
-         "-misched-topdown incompatible with -misched-bottomup");
-  return new ScheduleDAGMILive(
-      C, std::make_unique<InstructionShuffler>(Alternate, TopDown));
-}
-
-static MachineSchedRegistry ShufflerRegistry(
-  "shuffle", "Shuffle machine instructions alternating directions",
-  createInstructionShuffler);
-#endif // !NDEBUG
-
-//===----------------------------------------------------------------------===//
-// GraphWriter support for ScheduleDAGMILive.
-//===----------------------------------------------------------------------===//
-
-#ifndef NDEBUG
-namespace llvm {
-
-template<> struct GraphTraits<
-  ScheduleDAGMI*> : public GraphTraits<ScheduleDAG*> {};
-
-template<>
-struct DOTGraphTraits<ScheduleDAGMI*> : public DefaultDOTGraphTraits {
-  DOTGraphTraits(bool isSimple = false) : DefaultDOTGraphTraits(isSimple) {}
-
-  static std::string getGraphName(const ScheduleDAG *G) {
-    return std::string(G->MF.getName());
-  }
-
-  static bool renderGraphFromBottomUp() {
-    return true;
-  }
-
+ 
+//===----------------------------------------------------------------------===// 
+// PostGenericScheduler - Generic PostRA implementation of MachineSchedStrategy. 
+//===----------------------------------------------------------------------===// 
+ 
+void PostGenericScheduler::initialize(ScheduleDAGMI *Dag) { 
+  DAG = Dag; 
+  SchedModel = DAG->getSchedModel(); 
+  TRI = DAG->TRI; 
+ 
+  Rem.init(DAG, SchedModel); 
+  Top.init(DAG, SchedModel, &Rem); 
+  BotRoots.clear(); 
+ 
+  // Initialize the HazardRecognizers. If itineraries don't exist, are empty, 
+  // or are disabled, then these HazardRecs will be disabled. 
+  const InstrItineraryData *Itin = SchedModel->getInstrItineraries(); 
+  if (!Top.HazardRec) { 
+    Top.HazardRec = 
+        DAG->MF.getSubtarget().getInstrInfo()->CreateTargetMIHazardRecognizer( 
+            Itin, DAG); 
+  } 
+} 
+ 
+void PostGenericScheduler::registerRoots() { 
+  Rem.CriticalPath = DAG->ExitSU.getDepth(); 
+ 
+  // Some roots may not feed into ExitSU. Check all of them in case. 
+  for (const SUnit *SU : BotRoots) { 
+    if (SU->getDepth() > Rem.CriticalPath) 
+      Rem.CriticalPath = SU->getDepth(); 
+  } 
+  LLVM_DEBUG(dbgs() << "Critical Path: (PGS-RR) " << Rem.CriticalPath << '\n'); 
+  if (DumpCriticalPathLength) { 
+    errs() << "Critical Path(PGS-RR ): " << Rem.CriticalPath << " \n"; 
+  } 
+} 
+ 
+/// Apply a set of heuristics to a new candidate for PostRA scheduling. 
+/// 
+/// \param Cand provides the policy and current best candidate. 
+/// \param TryCand refers to the next SUnit candidate, otherwise uninitialized. 
+void PostGenericScheduler::tryCandidate(SchedCandidate &Cand, 
+                                        SchedCandidate &TryCand) { 
+  // Initialize the candidate if needed. 
+  if (!Cand.isValid()) { 
+    TryCand.Reason = NodeOrder; 
+    return; 
+  } 
+ 
+  // Prioritize instructions that read unbuffered resources by stall cycles. 
+  if (tryLess(Top.getLatencyStallCycles(TryCand.SU), 
+              Top.getLatencyStallCycles(Cand.SU), TryCand, Cand, Stall)) 
+    return; 
+ 
+  // Keep clustered nodes together. 
+  if (tryGreater(TryCand.SU == DAG->getNextClusterSucc(), 
+                 Cand.SU == DAG->getNextClusterSucc(), 
+                 TryCand, Cand, Cluster)) 
+    return; 
+ 
+  // Avoid critical resource consumption and balance the schedule. 
+  if (tryLess(TryCand.ResDelta.CritResources, Cand.ResDelta.CritResources, 
+              TryCand, Cand, ResourceReduce)) 
+    return; 
+  if (tryGreater(TryCand.ResDelta.DemandedResources, 
+                 Cand.ResDelta.DemandedResources, 
+                 TryCand, Cand, ResourceDemand)) 
+    return; 
+ 
+  // Avoid serializing long latency dependence chains. 
+  if (Cand.Policy.ReduceLatency && tryLatency(TryCand, Cand, Top)) { 
+    return; 
+  } 
+ 
+  // Fall through to original instruction order. 
+  if (TryCand.SU->NodeNum < Cand.SU->NodeNum) 
+    TryCand.Reason = NodeOrder; 
+} 
+ 
+void PostGenericScheduler::pickNodeFromQueue(SchedCandidate &Cand) { 
+  ReadyQueue &Q = Top.Available; 
+  for (SUnit *SU : Q) { 
+    SchedCandidate TryCand(Cand.Policy); 
+    TryCand.SU = SU; 
+    TryCand.AtTop = true; 
+    TryCand.initResourceDelta(DAG, SchedModel); 
+    tryCandidate(Cand, TryCand); 
+    if (TryCand.Reason != NoCand) { 
+      Cand.setBest(TryCand); 
+      LLVM_DEBUG(traceCandidate(Cand)); 
+    } 
+  } 
+} 
+ 
+/// Pick the next node to schedule. 
+SUnit *PostGenericScheduler::pickNode(bool &IsTopNode) { 
+  if (DAG->top() == DAG->bottom()) { 
+    assert(Top.Available.empty() && Top.Pending.empty() && "ReadyQ garbage"); 
+    return nullptr; 
+  } 
+  SUnit *SU; 
+  do { 
+    SU = Top.pickOnlyChoice(); 
+    if (SU) { 
+      tracePick(Only1, true); 
+    } else { 
+      CandPolicy NoPolicy; 
+      SchedCandidate TopCand(NoPolicy); 
+      // Set the top-down policy based on the state of the current top zone and 
+      // the instructions outside the zone, including the bottom zone. 
+      setPolicy(TopCand.Policy, /*IsPostRA=*/true, Top, nullptr); 
+      pickNodeFromQueue(TopCand); 
+      assert(TopCand.Reason != NoCand && "failed to find a candidate"); 
+      tracePick(TopCand); 
+      SU = TopCand.SU; 
+    } 
+  } while (SU->isScheduled); 
+ 
+  IsTopNode = true; 
+  Top.removeReady(SU); 
+ 
+  LLVM_DEBUG(dbgs() << "Scheduling SU(" << SU->NodeNum << ") " 
+                    << *SU->getInstr()); 
+  return SU; 
+} 
+ 
+/// Called after ScheduleDAGMI has scheduled an instruction and updated 
+/// scheduled/remaining flags in the DAG nodes. 
+void PostGenericScheduler::schedNode(SUnit *SU, bool IsTopNode) { 
+  SU->TopReadyCycle = std::max(SU->TopReadyCycle, Top.getCurrCycle()); 
+  Top.bumpNode(SU); 
+} 
+ 
+ScheduleDAGMI *llvm::createGenericSchedPostRA(MachineSchedContext *C) { 
+  return new ScheduleDAGMI(C, std::make_unique<PostGenericScheduler>(C), 
+                           /*RemoveKillFlags=*/true); 
+} 
+ 
+//===----------------------------------------------------------------------===// 
+// ILP Scheduler. Currently for experimental analysis of heuristics. 
+//===----------------------------------------------------------------------===// 
+ 
+namespace { 
+ 
+/// Order nodes by the ILP metric. 
+struct ILPOrder { 
+  const SchedDFSResult *DFSResult = nullptr; 
+  const BitVector *ScheduledTrees = nullptr; 
+  bool MaximizeILP; 
+ 
+  ILPOrder(bool MaxILP) : MaximizeILP(MaxILP) {} 
+ 
+  /// Apply a less-than relation on node priority. 
+  /// 
+  /// (Return true if A comes after B in the Q.) 
+  bool operator()(const SUnit *A, const SUnit *B) const { 
+    unsigned SchedTreeA = DFSResult->getSubtreeID(A); 
+    unsigned SchedTreeB = DFSResult->getSubtreeID(B); 
+    if (SchedTreeA != SchedTreeB) { 
+      // Unscheduled trees have lower priority. 
+      if (ScheduledTrees->test(SchedTreeA) != ScheduledTrees->test(SchedTreeB)) 
+        return ScheduledTrees->test(SchedTreeB); 
+ 
+      // Trees with shallower connections have have lower priority. 
+      if (DFSResult->getSubtreeLevel(SchedTreeA) 
+          != DFSResult->getSubtreeLevel(SchedTreeB)) { 
+        return DFSResult->getSubtreeLevel(SchedTreeA) 
+          < DFSResult->getSubtreeLevel(SchedTreeB); 
+      } 
+    } 
+    if (MaximizeILP) 
+      return DFSResult->getILP(A) < DFSResult->getILP(B); 
+    else 
+      return DFSResult->getILP(A) > DFSResult->getILP(B); 
+  } 
+}; 
+ 
+/// Schedule based on the ILP metric. 
+class ILPScheduler : public MachineSchedStrategy { 
+  ScheduleDAGMILive *DAG = nullptr; 
+  ILPOrder Cmp; 
+ 
+  std::vector<SUnit*> ReadyQ; 
+ 
+public: 
+  ILPScheduler(bool MaximizeILP) : Cmp(MaximizeILP) {} 
+ 
+  void initialize(ScheduleDAGMI *dag) override { 
+    assert(dag->hasVRegLiveness() && "ILPScheduler needs vreg liveness"); 
+    DAG = static_cast<ScheduleDAGMILive*>(dag); 
+    DAG->computeDFSResult(); 
+    Cmp.DFSResult = DAG->getDFSResult(); 
+    Cmp.ScheduledTrees = &DAG->getScheduledTrees(); 
+    ReadyQ.clear(); 
+  } 
+ 
+  void registerRoots() override { 
+    // Restore the heap in ReadyQ with the updated DFS results. 
+    std::make_heap(ReadyQ.begin(), ReadyQ.end(), Cmp); 
+  } 
+ 
+  /// Implement MachineSchedStrategy interface. 
+  /// ----------------------------------------- 
+ 
+  /// Callback to select the highest priority node from the ready Q. 
+  SUnit *pickNode(bool &IsTopNode) override { 
+    if (ReadyQ.empty()) return nullptr; 
+    std::pop_heap(ReadyQ.begin(), ReadyQ.end(), Cmp); 
+    SUnit *SU = ReadyQ.back(); 
+    ReadyQ.pop_back(); 
+    IsTopNode = false; 
+    LLVM_DEBUG(dbgs() << "Pick node " 
+                      << "SU(" << SU->NodeNum << ") " 
+                      << " ILP: " << DAG->getDFSResult()->getILP(SU) 
+                      << " Tree: " << DAG->getDFSResult()->getSubtreeID(SU) 
+                      << " @" 
+                      << DAG->getDFSResult()->getSubtreeLevel( 
+                             DAG->getDFSResult()->getSubtreeID(SU)) 
+                      << '\n' 
+                      << "Scheduling " << *SU->getInstr()); 
+    return SU; 
+  } 
+ 
+  /// Scheduler callback to notify that a new subtree is scheduled. 
+  void scheduleTree(unsigned SubtreeID) override { 
+    std::make_heap(ReadyQ.begin(), ReadyQ.end(), Cmp); 
+  } 
+ 
+  /// Callback after a node is scheduled. Mark a newly scheduled tree, notify 
+  /// DFSResults, and resort the priority Q. 
+  void schedNode(SUnit *SU, bool IsTopNode) override { 
+    assert(!IsTopNode && "SchedDFSResult needs bottom-up"); 
+  } 
+ 
+  void releaseTopNode(SUnit *) override { /*only called for top roots*/ } 
+ 
+  void releaseBottomNode(SUnit *SU) override { 
+    ReadyQ.push_back(SU); 
+    std::push_heap(ReadyQ.begin(), ReadyQ.end(), Cmp); 
+  } 
+}; 
+ 
+} // end anonymous namespace 
+ 
+static ScheduleDAGInstrs *createILPMaxScheduler(MachineSchedContext *C) { 
+  return new ScheduleDAGMILive(C, std::make_unique<ILPScheduler>(true)); 
+} 
+static ScheduleDAGInstrs *createILPMinScheduler(MachineSchedContext *C) { 
+  return new ScheduleDAGMILive(C, std::make_unique<ILPScheduler>(false)); 
+} 
+ 
+static MachineSchedRegistry ILPMaxRegistry( 
+  "ilpmax", "Schedule bottom-up for max ILP", createILPMaxScheduler); 
+static MachineSchedRegistry ILPMinRegistry( 
+  "ilpmin", "Schedule bottom-up for min ILP", createILPMinScheduler); 
+ 
+//===----------------------------------------------------------------------===// 
+// Machine Instruction Shuffler for Correctness Testing 
+//===----------------------------------------------------------------------===// 
+ 
+#ifndef NDEBUG 
+namespace { 
+ 
+/// Apply a less-than relation on the node order, which corresponds to the 
+/// instruction order prior to scheduling. IsReverse implements greater-than. 
+template<bool IsReverse> 
+struct SUnitOrder { 
+  bool operator()(SUnit *A, SUnit *B) const { 
+    if (IsReverse) 
+      return A->NodeNum > B->NodeNum; 
+    else 
+      return A->NodeNum < B->NodeNum; 
+  } 
+}; 
+ 
+/// Reorder instructions as much as possible. 
+class InstructionShuffler : public MachineSchedStrategy { 
+  bool IsAlternating; 
+  bool IsTopDown; 
+ 
+  // Using a less-than relation (SUnitOrder<false>) for the TopQ priority 
+  // gives nodes with a higher number higher priority causing the latest 
+  // instructions to be scheduled first. 
+  PriorityQueue<SUnit*, std::vector<SUnit*>, SUnitOrder<false>> 
+    TopQ; 
+ 
+  // When scheduling bottom-up, use greater-than as the queue priority. 
+  PriorityQueue<SUnit*, std::vector<SUnit*>, SUnitOrder<true>> 
+    BottomQ; 
+ 
+public: 
+  InstructionShuffler(bool alternate, bool topdown) 
+    : IsAlternating(alternate), IsTopDown(topdown) {} 
+ 
+  void initialize(ScheduleDAGMI*) override { 
+    TopQ.clear(); 
+    BottomQ.clear(); 
+  } 
+ 
+  /// Implement MachineSchedStrategy interface. 
+  /// ----------------------------------------- 
+ 
+  SUnit *pickNode(bool &IsTopNode) override { 
+    SUnit *SU; 
+    if (IsTopDown) { 
+      do { 
+        if (TopQ.empty()) return nullptr; 
+        SU = TopQ.top(); 
+        TopQ.pop(); 
+      } while (SU->isScheduled); 
+      IsTopNode = true; 
+    } else { 
+      do { 
+        if (BottomQ.empty()) return nullptr; 
+        SU = BottomQ.top(); 
+        BottomQ.pop(); 
+      } while (SU->isScheduled); 
+      IsTopNode = false; 
+    } 
+    if (IsAlternating) 
+      IsTopDown = !IsTopDown; 
+    return SU; 
+  } 
+ 
+  void schedNode(SUnit *SU, bool IsTopNode) override {} 
+ 
+  void releaseTopNode(SUnit *SU) override { 
+    TopQ.push(SU); 
+  } 
+  void releaseBottomNode(SUnit *SU) override { 
+    BottomQ.push(SU); 
+  } 
+}; 
+ 
+} // end anonymous namespace 
+ 
+static ScheduleDAGInstrs *createInstructionShuffler(MachineSchedContext *C) { 
+  bool Alternate = !ForceTopDown && !ForceBottomUp; 
+  bool TopDown = !ForceBottomUp; 
+  assert((TopDown || !ForceTopDown) && 
+         "-misched-topdown incompatible with -misched-bottomup"); 
+  return new ScheduleDAGMILive( 
+      C, std::make_unique<InstructionShuffler>(Alternate, TopDown)); 
+} 
+ 
+static MachineSchedRegistry ShufflerRegistry( 
+  "shuffle", "Shuffle machine instructions alternating directions", 
+  createInstructionShuffler); 
+#endif // !NDEBUG 
+ 
+//===----------------------------------------------------------------------===// 
+// GraphWriter support for ScheduleDAGMILive. 
+//===----------------------------------------------------------------------===// 
+ 
+#ifndef NDEBUG 
+namespace llvm { 
+ 
+template<> struct GraphTraits< 
+  ScheduleDAGMI*> : public GraphTraits<ScheduleDAG*> {}; 
+ 
+template<> 
+struct DOTGraphTraits<ScheduleDAGMI*> : public DefaultDOTGraphTraits { 
+  DOTGraphTraits(bool isSimple = false) : DefaultDOTGraphTraits(isSimple) {} 
+ 
+  static std::string getGraphName(const ScheduleDAG *G) { 
+    return std::string(G->MF.getName()); 
+  } 
+ 
+  static bool renderGraphFromBottomUp() { 
+    return true; 
+  } 
+ 
   static bool isNodeHidden(const SUnit *Node, const ScheduleDAG *G) {
-    if (ViewMISchedCutoff == 0)
-      return false;
-    return (Node->Preds.size() > ViewMISchedCutoff
-         || Node->Succs.size() > ViewMISchedCutoff);
-  }
-
-  /// If you want to override the dot attributes printed for a particular
-  /// edge, override this method.
-  static std::string getEdgeAttributes(const SUnit *Node,
-                                       SUnitIterator EI,
-                                       const ScheduleDAG *Graph) {
-    if (EI.isArtificialDep())
-      return "color=cyan,style=dashed";
-    if (EI.isCtrlDep())
-      return "color=blue,style=dashed";
-    return "";
-  }
-
-  static std::string getNodeLabel(const SUnit *SU, const ScheduleDAG *G) {
-    std::string Str;
-    raw_string_ostream SS(Str);
-    const ScheduleDAGMI *DAG = static_cast<const ScheduleDAGMI*>(G);
-    const SchedDFSResult *DFS = DAG->hasVRegLiveness() ?
-      static_cast<const ScheduleDAGMILive*>(G)->getDFSResult() : nullptr;
-    SS << "SU:" << SU->NodeNum;
-    if (DFS)
-      SS << " I:" << DFS->getNumInstrs(SU);
-    return SS.str();
-  }
-
-  static std::string getNodeDescription(const SUnit *SU, const ScheduleDAG *G) {
-    return G->getGraphNodeLabel(SU);
-  }
-
-  static std::string getNodeAttributes(const SUnit *N, const ScheduleDAG *G) {
-    std::string Str("shape=Mrecord");
-    const ScheduleDAGMI *DAG = static_cast<const ScheduleDAGMI*>(G);
-    const SchedDFSResult *DFS = DAG->hasVRegLiveness() ?
-      static_cast<const ScheduleDAGMILive*>(G)->getDFSResult() : nullptr;
-    if (DFS) {
-      Str += ",style=filled,fillcolor=\"#";
-      Str += DOT::getColorString(DFS->getSubtreeID(N));
-      Str += '"';
-    }
-    return Str;
-  }
-};
-
-} // end namespace llvm
-#endif // NDEBUG
-
-/// viewGraph - Pop up a ghostview window with the reachable parts of the DAG
-/// rendered using 'dot'.
-void ScheduleDAGMI::viewGraph(const Twine &Name, const Twine &Title) {
-#ifndef NDEBUG
-  ViewGraph(this, Name, false, Title);
-#else
-  errs() << "ScheduleDAGMI::viewGraph is only available in debug builds on "
-         << "systems with Graphviz or gv!\n";
-#endif  // NDEBUG
-}
-
-/// Out-of-line implementation with no arguments is handy for gdb.
-void ScheduleDAGMI::viewGraph() {
-  viewGraph(getDAGName(), "Scheduling-Units Graph for " + getDAGName());
-}
+    if (ViewMISchedCutoff == 0) 
+      return false; 
+    return (Node->Preds.size() > ViewMISchedCutoff 
+         || Node->Succs.size() > ViewMISchedCutoff); 
+  } 
+ 
+  /// If you want to override the dot attributes printed for a particular 
+  /// edge, override this method. 
+  static std::string getEdgeAttributes(const SUnit *Node, 
+                                       SUnitIterator EI, 
+                                       const ScheduleDAG *Graph) { 
+    if (EI.isArtificialDep()) 
+      return "color=cyan,style=dashed"; 
+    if (EI.isCtrlDep()) 
+      return "color=blue,style=dashed"; 
+    return ""; 
+  } 
+ 
+  static std::string getNodeLabel(const SUnit *SU, const ScheduleDAG *G) { 
+    std::string Str; 
+    raw_string_ostream SS(Str); 
+    const ScheduleDAGMI *DAG = static_cast<const ScheduleDAGMI*>(G); 
+    const SchedDFSResult *DFS = DAG->hasVRegLiveness() ? 
+      static_cast<const ScheduleDAGMILive*>(G)->getDFSResult() : nullptr; 
+    SS << "SU:" << SU->NodeNum; 
+    if (DFS) 
+      SS << " I:" << DFS->getNumInstrs(SU); 
+    return SS.str(); 
+  } 
+ 
+  static std::string getNodeDescription(const SUnit *SU, const ScheduleDAG *G) { 
+    return G->getGraphNodeLabel(SU); 
+  } 
+ 
+  static std::string getNodeAttributes(const SUnit *N, const ScheduleDAG *G) { 
+    std::string Str("shape=Mrecord"); 
+    const ScheduleDAGMI *DAG = static_cast<const ScheduleDAGMI*>(G); 
+    const SchedDFSResult *DFS = DAG->hasVRegLiveness() ? 
+      static_cast<const ScheduleDAGMILive*>(G)->getDFSResult() : nullptr; 
+    if (DFS) { 
+      Str += ",style=filled,fillcolor=\"#"; 
+      Str += DOT::getColorString(DFS->getSubtreeID(N)); 
+      Str += '"'; 
+    } 
+    return Str; 
+  } 
+}; 
+ 
+} // end namespace llvm 
+#endif // NDEBUG 
+ 
+/// viewGraph - Pop up a ghostview window with the reachable parts of the DAG 
+/// rendered using 'dot'. 
+void ScheduleDAGMI::viewGraph(const Twine &Name, const Twine &Title) { 
+#ifndef NDEBUG 
+  ViewGraph(this, Name, false, Title); 
+#else 
+  errs() << "ScheduleDAGMI::viewGraph is only available in debug builds on " 
+         << "systems with Graphviz or gv!\n"; 
+#endif  // NDEBUG 
+} 
+ 
+/// Out-of-line implementation with no arguments is handy for gdb. 
+void ScheduleDAGMI::viewGraph() { 
+  viewGraph(getDAGName(), "Scheduling-Units Graph for " + getDAGName()); 
+}