llvm16 targets

1 files changed, 678 insertions, 0 deletions

diff --git a/contrib/libs/llvm16/lib/CodeGen/TargetRegisterInfo.cpp b/contrib/libs/llvm16/lib/CodeGen/TargetRegisterInfo.cpp
new file mode 100644
index 00000000000..a41d5999d96
--- /dev/null
+++ b/contrib/libs/llvm16/lib/CodeGen/TargetRegisterInfo.cpp
@@ -0,0 +1,678 @@
+//==- TargetRegisterInfo.cpp - Target Register Information Implementation --==//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the TargetRegisterInfo interface.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/TargetRegisterInfo.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/BinaryFormat/Dwarf.h"
+#include "llvm/CodeGen/LiveInterval.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/TargetFrameLowering.h"
+#include "llvm/CodeGen/TargetInstrInfo.h"
+#include "llvm/CodeGen/TargetSubtargetInfo.h"
+#include "llvm/CodeGen/VirtRegMap.h"
+#include "llvm/Config/llvm-config.h"
+#include "llvm/IR/Attributes.h"
+#include "llvm/IR/DebugInfoMetadata.h"
+#include "llvm/IR/Function.h"
+#include "llvm/MC/MCRegisterInfo.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/MachineValueType.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/Printable.h"
+#include "llvm/Support/raw_ostream.h"
+#include <cassert>
+#include <utility>
+
+#define DEBUG_TYPE "target-reg-info"
+
+using namespace llvm;
+
+static cl::opt<unsigned>
+    HugeSizeForSplit("huge-size-for-split", cl::Hidden,
+                     cl::desc("A threshold of live range size which may cause "
+                              "high compile time cost in global splitting."),
+                     cl::init(5000));
+
+TargetRegisterInfo::TargetRegisterInfo(const TargetRegisterInfoDesc *ID,
+                             regclass_iterator RCB, regclass_iterator RCE,
+                             const char *const *SRINames,
+                             const LaneBitmask *SRILaneMasks,
+                             LaneBitmask SRICoveringLanes,
+                             const RegClassInfo *const RCIs,
+                             unsigned Mode)
+  : InfoDesc(ID), SubRegIndexNames(SRINames),
+    SubRegIndexLaneMasks(SRILaneMasks),
+    RegClassBegin(RCB), RegClassEnd(RCE),
+    CoveringLanes(SRICoveringLanes),
+    RCInfos(RCIs), HwMode(Mode) {
+}
+
+TargetRegisterInfo::~TargetRegisterInfo() = default;
+
+bool TargetRegisterInfo::shouldRegionSplitForVirtReg(
+    const MachineFunction &MF, const LiveInterval &VirtReg) const {
+  const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
+  const MachineRegisterInfo &MRI = MF.getRegInfo();
+  MachineInstr *MI = MRI.getUniqueVRegDef(VirtReg.reg());
+  if (MI && TII->isTriviallyReMaterializable(*MI) &&
+      VirtReg.size() > HugeSizeForSplit)
+    return false;
+  return true;
+}
+
+void TargetRegisterInfo::markSuperRegs(BitVector &RegisterSet,
+                                       MCRegister Reg) const {
+  for (MCSuperRegIterator AI(Reg, this, true); AI.isValid(); ++AI)
+    RegisterSet.set(*AI);
+}
+
+bool TargetRegisterInfo::checkAllSuperRegsMarked(const BitVector &RegisterSet,
+    ArrayRef<MCPhysReg> Exceptions) const {
+  // Check that all super registers of reserved regs are reserved as well.
+  BitVector Checked(getNumRegs());
+  for (unsigned Reg : RegisterSet.set_bits()) {
+    if (Checked[Reg])
+      continue;
+    for (MCSuperRegIterator SR(Reg, this); SR.isValid(); ++SR) {
+      if (!RegisterSet[*SR] && !is_contained(Exceptions, Reg)) {
+        dbgs() << "Error: Super register " << printReg(*SR, this)
+               << " of reserved register " << printReg(Reg, this)
+               << " is not reserved.\n";
+        return false;
+      }
+
+      // We transitively check superregs. So we can remember this for later
+      // to avoid compiletime explosion in deep register hierarchies.
+      Checked.set(*SR);
+    }
+  }
+  return true;
+}
+
+namespace llvm {
+
+Printable printReg(Register Reg, const TargetRegisterInfo *TRI,
+                   unsigned SubIdx, const MachineRegisterInfo *MRI) {
+  return Printable([Reg, TRI, SubIdx, MRI](raw_ostream &OS) {
+    if (!Reg)
+      OS << "$noreg";
+    else if (Register::isStackSlot(Reg))
+      OS << "SS#" << Register::stackSlot2Index(Reg);
+    else if (Reg.isVirtual()) {
+      StringRef Name = MRI ? MRI->getVRegName(Reg) : "";
+      if (Name != "") {
+        OS << '%' << Name;
+      } else {
+        OS << '%' << Register::virtReg2Index(Reg);
+      }
+    } else if (!TRI)
+      OS << '$' << "physreg" << Reg;
+    else if (Reg < TRI->getNumRegs()) {
+      OS << '$';
+      printLowerCase(TRI->getName(Reg), OS);
+    } else
+      llvm_unreachable("Register kind is unsupported.");
+
+    if (SubIdx) {
+      if (TRI)
+        OS << ':' << TRI->getSubRegIndexName(SubIdx);
+      else
+        OS << ":sub(" << SubIdx << ')';
+    }
+  });
+}
+
+Printable printRegUnit(unsigned Unit, const TargetRegisterInfo *TRI) {
+  return Printable([Unit, TRI](raw_ostream &OS) {
+    // Generic printout when TRI is missing.
+    if (!TRI) {
+      OS << "Unit~" << Unit;
+      return;
+    }
+
+    // Check for invalid register units.
+    if (Unit >= TRI->getNumRegUnits()) {
+      OS << "BadUnit~" << Unit;
+      return;
+    }
+
+    // Normal units have at least one root.
+    MCRegUnitRootIterator Roots(Unit, TRI);
+    assert(Roots.isValid() && "Unit has no roots.");
+    OS << TRI->getName(*Roots);
+    for (++Roots; Roots.isValid(); ++Roots)
+      OS << '~' << TRI->getName(*Roots);
+  });
+}
+
+Printable printVRegOrUnit(unsigned Unit, const TargetRegisterInfo *TRI) {
+  return Printable([Unit, TRI](raw_ostream &OS) {
+    if (Register::isVirtualRegister(Unit)) {
+      OS << '%' << Register::virtReg2Index(Unit);
+    } else {
+      OS << printRegUnit(Unit, TRI);
+    }
+  });
+}
+
+Printable printRegClassOrBank(Register Reg, const MachineRegisterInfo &RegInfo,
+                              const TargetRegisterInfo *TRI) {
+  return Printable([Reg, &RegInfo, TRI](raw_ostream &OS) {
+    if (RegInfo.getRegClassOrNull(Reg))
+      OS << StringRef(TRI->getRegClassName(RegInfo.getRegClass(Reg))).lower();
+    else if (RegInfo.getRegBankOrNull(Reg))
+      OS << StringRef(RegInfo.getRegBankOrNull(Reg)->getName()).lower();
+    else {
+      OS << "_";
+      assert((RegInfo.def_empty(Reg) || RegInfo.getType(Reg).isValid()) &&
+             "Generic registers must have a valid type");
+    }
+  });
+}
+
+} // end namespace llvm
+
+/// getAllocatableClass - Return the maximal subclass of the given register
+/// class that is alloctable, or NULL.
+const TargetRegisterClass *
+TargetRegisterInfo::getAllocatableClass(const TargetRegisterClass *RC) const {
+  if (!RC || RC->isAllocatable())
+    return RC;
+
+  for (BitMaskClassIterator It(RC->getSubClassMask(), *this); It.isValid();
+       ++It) {
+    const TargetRegisterClass *SubRC = getRegClass(It.getID());
+    if (SubRC->isAllocatable())
+      return SubRC;
+  }
+  return nullptr;
+}
+
+/// getMinimalPhysRegClass - Returns the Register Class of a physical
+/// register of the given type, picking the most sub register class of
+/// the right type that contains this physreg.
+const TargetRegisterClass *
+TargetRegisterInfo::getMinimalPhysRegClass(MCRegister reg, MVT VT) const {
+  assert(Register::isPhysicalRegister(reg) &&
+         "reg must be a physical register");
+
+  // Pick the most sub register class of the right type that contains
+  // this physreg.
+  const TargetRegisterClass* BestRC = nullptr;
+  for (const TargetRegisterClass* RC : regclasses()) {
+    if ((VT == MVT::Other || isTypeLegalForClass(*RC, VT)) &&
+        RC->contains(reg) && (!BestRC || BestRC->hasSubClass(RC)))
+      BestRC = RC;
+  }
+
+  assert(BestRC && "Couldn't find the register class");
+  return BestRC;
+}
+
+const TargetRegisterClass *
+TargetRegisterInfo::getMinimalPhysRegClassLLT(MCRegister reg, LLT Ty) const {
+  assert(Register::isPhysicalRegister(reg) &&
+         "reg must be a physical register");
+
+  // Pick the most sub register class of the right type that contains
+  // this physreg.
+  const TargetRegisterClass *BestRC = nullptr;
+  for (const TargetRegisterClass *RC : regclasses()) {
+    if ((!Ty.isValid() || isTypeLegalForClass(*RC, Ty)) && RC->contains(reg) &&
+        (!BestRC || BestRC->hasSubClass(RC)))
+      BestRC = RC;
+  }
+
+  return BestRC;
+}
+
+/// getAllocatableSetForRC - Toggle the bits that represent allocatable
+/// registers for the specific register class.
+static void getAllocatableSetForRC(const MachineFunction &MF,
+                                   const TargetRegisterClass *RC, BitVector &R){
+  assert(RC->isAllocatable() && "invalid for nonallocatable sets");
+  ArrayRef<MCPhysReg> Order = RC->getRawAllocationOrder(MF);
+  for (MCPhysReg PR : Order)
+    R.set(PR);
+}
+
+BitVector TargetRegisterInfo::getAllocatableSet(const MachineFunction &MF,
+                                          const TargetRegisterClass *RC) const {
+  BitVector Allocatable(getNumRegs());
+  if (RC) {
+    // A register class with no allocatable subclass returns an empty set.
+    const TargetRegisterClass *SubClass = getAllocatableClass(RC);
+    if (SubClass)
+      getAllocatableSetForRC(MF, SubClass, Allocatable);
+  } else {
+    for (const TargetRegisterClass *C : regclasses())
+      if (C->isAllocatable())
+        getAllocatableSetForRC(MF, C, Allocatable);
+  }
+
+  // Mask out the reserved registers
+  const MachineRegisterInfo &MRI = MF.getRegInfo();
+  const BitVector &Reserved = MRI.getReservedRegs();
+  Allocatable.reset(Reserved);
+
+  return Allocatable;
+}
+
+static inline
+const TargetRegisterClass *firstCommonClass(const uint32_t *A,
+                                            const uint32_t *B,
+                                            const TargetRegisterInfo *TRI) {
+  for (unsigned I = 0, E = TRI->getNumRegClasses(); I < E; I += 32)
+    if (unsigned Common = *A++ & *B++)
+      return TRI->getRegClass(I + countTrailingZeros(Common));
+  return nullptr;
+}
+
+const TargetRegisterClass *
+TargetRegisterInfo::getCommonSubClass(const TargetRegisterClass *A,
+                                      const TargetRegisterClass *B) const {
+  // First take care of the trivial cases.
+  if (A == B)
+    return A;
+  if (!A || !B)
+    return nullptr;
+
+  // Register classes are ordered topologically, so the largest common
+  // sub-class it the common sub-class with the smallest ID.
+  return firstCommonClass(A->getSubClassMask(), B->getSubClassMask(), this);
+}
+
+const TargetRegisterClass *
+TargetRegisterInfo::getMatchingSuperRegClass(const TargetRegisterClass *A,
+                                             const TargetRegisterClass *B,
+                                             unsigned Idx) const {
+  assert(A && B && "Missing register class");
+  assert(Idx && "Bad sub-register index");
+
+  // Find Idx in the list of super-register indices.
+  for (SuperRegClassIterator RCI(B, this); RCI.isValid(); ++RCI)
+    if (RCI.getSubReg() == Idx)
+      // The bit mask contains all register classes that are projected into B
+      // by Idx. Find a class that is also a sub-class of A.
+      return firstCommonClass(RCI.getMask(), A->getSubClassMask(), this);
+  return nullptr;
+}
+
+const TargetRegisterClass *TargetRegisterInfo::
+getCommonSuperRegClass(const TargetRegisterClass *RCA, unsigned SubA,
+                       const TargetRegisterClass *RCB, unsigned SubB,
+                       unsigned &PreA, unsigned &PreB) const {
+  assert(RCA && SubA && RCB && SubB && "Invalid arguments");
+
+  // Search all pairs of sub-register indices that project into RCA and RCB
+  // respectively. This is quadratic, but usually the sets are very small. On
+  // most targets like X86, there will only be a single sub-register index
+  // (e.g., sub_16bit projecting into GR16).
+  //
+  // The worst case is a register class like DPR on ARM.
+  // We have indices dsub_0..dsub_7 projecting into that class.
+  //
+  // It is very common that one register class is a sub-register of the other.
+  // Arrange for RCA to be the larger register so the answer will be found in
+  // the first iteration. This makes the search linear for the most common
+  // case.
+  const TargetRegisterClass *BestRC = nullptr;
+  unsigned *BestPreA = &PreA;
+  unsigned *BestPreB = &PreB;
+  if (getRegSizeInBits(*RCA) < getRegSizeInBits(*RCB)) {
+    std::swap(RCA, RCB);
+    std::swap(SubA, SubB);
+    std::swap(BestPreA, BestPreB);
+  }
+
+  // Also terminate the search one we have found a register class as small as
+  // RCA.
+  unsigned MinSize = getRegSizeInBits(*RCA);
+
+  for (SuperRegClassIterator IA(RCA, this, true); IA.isValid(); ++IA) {
+    unsigned FinalA = composeSubRegIndices(IA.getSubReg(), SubA);
+    for (SuperRegClassIterator IB(RCB, this, true); IB.isValid(); ++IB) {
+      // Check if a common super-register class exists for this index pair.
+      const TargetRegisterClass *RC =
+        firstCommonClass(IA.getMask(), IB.getMask(), this);
+      if (!RC || getRegSizeInBits(*RC) < MinSize)
+        continue;
+
+      // The indexes must compose identically: PreA+SubA == PreB+SubB.
+      unsigned FinalB = composeSubRegIndices(IB.getSubReg(), SubB);
+      if (FinalA != FinalB)
+        continue;
+
+      // Is RC a better candidate than BestRC?
+      if (BestRC && getRegSizeInBits(*RC) >= getRegSizeInBits(*BestRC))
+        continue;
+
+      // Yes, RC is the smallest super-register seen so far.
+      BestRC = RC;
+      *BestPreA = IA.getSubReg();
+      *BestPreB = IB.getSubReg();
+
+      // Bail early if we reached MinSize. We won't find a better candidate.
+      if (getRegSizeInBits(*BestRC) == MinSize)
+        return BestRC;
+    }
+  }
+  return BestRC;
+}
+
+/// Check if the registers defined by the pair (RegisterClass, SubReg)
+/// share the same register file.
+static bool shareSameRegisterFile(const TargetRegisterInfo &TRI,
+                                  const TargetRegisterClass *DefRC,
+                                  unsigned DefSubReg,
+                                  const TargetRegisterClass *SrcRC,
+                                  unsigned SrcSubReg) {
+  // Same register class.
+  if (DefRC == SrcRC)
+    return true;
+
+  // Both operands are sub registers. Check if they share a register class.
+  unsigned SrcIdx, DefIdx;
+  if (SrcSubReg && DefSubReg) {
+    return TRI.getCommonSuperRegClass(SrcRC, SrcSubReg, DefRC, DefSubReg,
+                                      SrcIdx, DefIdx) != nullptr;
+  }
+
+  // At most one of the register is a sub register, make it Src to avoid
+  // duplicating the test.
+  if (!SrcSubReg) {
+    std::swap(DefSubReg, SrcSubReg);
+    std::swap(DefRC, SrcRC);
+  }
+
+  // One of the register is a sub register, check if we can get a superclass.
+  if (SrcSubReg)
+    return TRI.getMatchingSuperRegClass(SrcRC, DefRC, SrcSubReg) != nullptr;
+
+  // Plain copy.
+  return TRI.getCommonSubClass(DefRC, SrcRC) != nullptr;
+}
+
+bool TargetRegisterInfo::shouldRewriteCopySrc(const TargetRegisterClass *DefRC,
+                                              unsigned DefSubReg,
+                                              const TargetRegisterClass *SrcRC,
+                                              unsigned SrcSubReg) const {
+  // If this source does not incur a cross register bank copy, use it.
+  return shareSameRegisterFile(*this, DefRC, DefSubReg, SrcRC, SrcSubReg);
+}
+
+// Compute target-independent register allocator hints to help eliminate copies.
+bool TargetRegisterInfo::getRegAllocationHints(
+    Register VirtReg, ArrayRef<MCPhysReg> Order,
+    SmallVectorImpl<MCPhysReg> &Hints, const MachineFunction &MF,
+    const VirtRegMap *VRM, const LiveRegMatrix *Matrix) const {
+  const MachineRegisterInfo &MRI = MF.getRegInfo();
+  const std::pair<Register, SmallVector<Register, 4>> &Hints_MRI =
+    MRI.getRegAllocationHints(VirtReg);
+
+  SmallSet<Register, 32> HintedRegs;
+  // First hint may be a target hint.
+  bool Skip = (Hints_MRI.first != 0);
+  for (auto Reg : Hints_MRI.second) {
+    if (Skip) {
+      Skip = false;
+      continue;
+    }
+
+    // Target-independent hints are either a physical or a virtual register.
+    Register Phys = Reg;
+    if (VRM && Phys.isVirtual())
+      Phys = VRM->getPhys(Phys);
+
+    // Don't add the same reg twice (Hints_MRI may contain multiple virtual
+    // registers allocated to the same physreg).
+    if (!HintedRegs.insert(Phys).second)
+      continue;
+    // Check that Phys is a valid hint in VirtReg's register class.
+    if (!Phys.isPhysical())
+      continue;
+    if (MRI.isReserved(Phys))
+      continue;
+    // Check that Phys is in the allocation order. We shouldn't heed hints
+    // from VirtReg's register class if they aren't in the allocation order. The
+    // target probably has a reason for removing the register.
+    if (!is_contained(Order, Phys))
+      continue;
+
+    // All clear, tell the register allocator to prefer this register.
+    Hints.push_back(Phys);
+  }
+  return false;
+}
+
+bool TargetRegisterInfo::isCalleeSavedPhysReg(
+    MCRegister PhysReg, const MachineFunction &MF) const {
+  if (PhysReg == 0)
+    return false;
+  const uint32_t *callerPreservedRegs =
+      getCallPreservedMask(MF, MF.getFunction().getCallingConv());
+  if (callerPreservedRegs) {
+    assert(Register::isPhysicalRegister(PhysReg) &&
+           "Expected physical register");
+    return (callerPreservedRegs[PhysReg / 32] >> PhysReg % 32) & 1;
+  }
+  return false;
+}
+
+bool TargetRegisterInfo::canRealignStack(const MachineFunction &MF) const {
+  return !MF.getFunction().hasFnAttribute("no-realign-stack");
+}
+
+bool TargetRegisterInfo::shouldRealignStack(const MachineFunction &MF) const {
+  const MachineFrameInfo &MFI = MF.getFrameInfo();
+  const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
+  const Function &F = MF.getFunction();
+  return F.hasFnAttribute("stackrealign") ||
+         (MFI.getMaxAlign() > TFI->getStackAlign()) ||
+         F.hasFnAttribute(Attribute::StackAlignment);
+}
+
+bool TargetRegisterInfo::regmaskSubsetEqual(const uint32_t *mask0,
+                                            const uint32_t *mask1) const {
+  unsigned N = (getNumRegs()+31) / 32;
+  for (unsigned I = 0; I < N; ++I)
+    if ((mask0[I] & mask1[I]) != mask0[I])
+      return false;
+  return true;
+}
+
+unsigned
+TargetRegisterInfo::getRegSizeInBits(Register Reg,
+                                     const MachineRegisterInfo &MRI) const {
+  const TargetRegisterClass *RC{};
+  if (Reg.isPhysical()) {
+    // The size is not directly available for physical registers.
+    // Instead, we need to access a register class that contains Reg and
+    // get the size of that register class.
+    RC = getMinimalPhysRegClass(Reg);
+  } else {
+    LLT Ty = MRI.getType(Reg);
+    unsigned RegSize = Ty.isValid() ? Ty.getSizeInBits() : 0;
+    // If Reg is not a generic register, query the register class to
+    // get its size.
+    if (RegSize)
+      return RegSize;
+    // Since Reg is not a generic register, it must have a register class.
+    RC = MRI.getRegClass(Reg);
+  }
+  assert(RC && "Unable to deduce the register class");
+  return getRegSizeInBits(*RC);
+}
+
+bool TargetRegisterInfo::getCoveringSubRegIndexes(
+    const MachineRegisterInfo &MRI, const TargetRegisterClass *RC,
+    LaneBitmask LaneMask, SmallVectorImpl<unsigned> &NeededIndexes) const {
+  SmallVector<unsigned, 8> PossibleIndexes;
+  unsigned BestIdx = 0;
+  unsigned BestCover = 0;
+
+  for (unsigned Idx = 1, E = getNumSubRegIndices(); Idx < E; ++Idx) {
+    // Is this index even compatible with the given class?
+    if (getSubClassWithSubReg(RC, Idx) != RC)
+      continue;
+    LaneBitmask SubRegMask = getSubRegIndexLaneMask(Idx);
+    // Early exit if we found a perfect match.
+    if (SubRegMask == LaneMask) {
+      BestIdx = Idx;
+      break;
+    }
+
+    // The index must not cover any lanes outside \p LaneMask.
+    if ((SubRegMask & ~LaneMask).any())
+      continue;
+
+    unsigned PopCount = SubRegMask.getNumLanes();
+    PossibleIndexes.push_back(Idx);
+    if (PopCount > BestCover) {
+      BestCover = PopCount;
+      BestIdx = Idx;
+    }
+  }
+
+  // Abort if we cannot possibly implement the COPY with the given indexes.
+  if (BestIdx == 0)
+    return false;
+
+  NeededIndexes.push_back(BestIdx);
+
+  // Greedy heuristic: Keep iterating keeping the best covering subreg index
+  // each time.
+  LaneBitmask LanesLeft = LaneMask & ~getSubRegIndexLaneMask(BestIdx);
+  while (LanesLeft.any()) {
+    unsigned BestIdx = 0;
+    int BestCover = std::numeric_limits<int>::min();
+    for (unsigned Idx : PossibleIndexes) {
+      LaneBitmask SubRegMask = getSubRegIndexLaneMask(Idx);
+      // Early exit if we found a perfect match.
+      if (SubRegMask == LanesLeft) {
+        BestIdx = Idx;
+        break;
+      }
+
+      // Do not cover already-covered lanes to avoid creating cycles
+      // in copy bundles (= bundle contains copies that write to the
+      // registers).
+      if ((SubRegMask & ~LanesLeft).any())
+        continue;
+
+      // Try to cover as many of the remaining lanes as possible.
+      const int Cover = (SubRegMask & LanesLeft).getNumLanes();
+      if (Cover > BestCover) {
+        BestCover = Cover;
+        BestIdx = Idx;
+      }
+    }
+
+    if (BestIdx == 0)
+      return false; // Impossible to handle
+
+    NeededIndexes.push_back(BestIdx);
+
+    LanesLeft &= ~getSubRegIndexLaneMask(BestIdx);
+  }
+
+  return BestIdx;
+}
+
+Register
+TargetRegisterInfo::lookThruCopyLike(Register SrcReg,
+                                     const MachineRegisterInfo *MRI) const {
+  while (true) {
+    const MachineInstr *MI = MRI->getVRegDef(SrcReg);
+    if (!MI->isCopyLike())
+      return SrcReg;
+
+    Register CopySrcReg;
+    if (MI->isCopy())
+      CopySrcReg = MI->getOperand(1).getReg();
+    else {
+      assert(MI->isSubregToReg() && "Bad opcode for lookThruCopyLike");
+      CopySrcReg = MI->getOperand(2).getReg();
+    }
+
+    if (!CopySrcReg.isVirtual())
+      return CopySrcReg;
+
+    SrcReg = CopySrcReg;
+  }
+}
+
+Register TargetRegisterInfo::lookThruSingleUseCopyChain(
+    Register SrcReg, const MachineRegisterInfo *MRI) const {
+  while (true) {
+    const MachineInstr *MI = MRI->getVRegDef(SrcReg);
+    // Found the real definition, return it if it has a single use.
+    if (!MI->isCopyLike())
+      return MRI->hasOneNonDBGUse(SrcReg) ? SrcReg : Register();
+
+    Register CopySrcReg;
+    if (MI->isCopy())
+      CopySrcReg = MI->getOperand(1).getReg();
+    else {
+      assert(MI->isSubregToReg() && "Bad opcode for lookThruCopyLike");
+      CopySrcReg = MI->getOperand(2).getReg();
+    }
+
+    // Continue only if the next definition in the chain is for a virtual
+    // register that has a single use.
+    if (!CopySrcReg.isVirtual() || !MRI->hasOneNonDBGUse(CopySrcReg))
+      return Register();
+
+    SrcReg = CopySrcReg;
+  }
+}
+
+void TargetRegisterInfo::getOffsetOpcodes(
+    const StackOffset &Offset, SmallVectorImpl<uint64_t> &Ops) const {
+  assert(!Offset.getScalable() && "Scalable offsets are not handled");
+  DIExpression::appendOffset(Ops, Offset.getFixed());
+}
+
+DIExpression *
+TargetRegisterInfo::prependOffsetExpression(const DIExpression *Expr,
+                                            unsigned PrependFlags,
+                                            const StackOffset &Offset) const {
+  assert((PrependFlags &
+          ~(DIExpression::DerefBefore | DIExpression::DerefAfter |
+            DIExpression::StackValue | DIExpression::EntryValue)) == 0 &&
+         "Unsupported prepend flag");
+  SmallVector<uint64_t, 16> OffsetExpr;
+  if (PrependFlags & DIExpression::DerefBefore)
+    OffsetExpr.push_back(dwarf::DW_OP_deref);
+  getOffsetOpcodes(Offset, OffsetExpr);
+  if (PrependFlags & DIExpression::DerefAfter)
+    OffsetExpr.push_back(dwarf::DW_OP_deref);
+  return DIExpression::prependOpcodes(Expr, OffsetExpr,
+                                      PrependFlags & DIExpression::StackValue,
+                                      PrependFlags & DIExpression::EntryValue);
+}
+
+#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
+LLVM_DUMP_METHOD
+void TargetRegisterInfo::dumpReg(Register Reg, unsigned SubRegIndex,
+                                 const TargetRegisterInfo *TRI) {
+  dbgs() << printReg(Reg, TRI, SubRegIndex) << "\n";
+}
+#endif