Intermediate changes

commit_hash:2ec2671384dd8e604d41bc5c52c2f7858e4afea6

1 files changed, 0 insertions, 874 deletions

diff --git a/contrib/libs/llvm14/tools/llvm-diff/lib/DifferenceEngine.cpp b/contrib/libs/llvm14/tools/llvm-diff/lib/DifferenceEngine.cpp
deleted file mode 100644
index 4bdefcdc175..00000000000
--- a/contrib/libs/llvm14/tools/llvm-diff/lib/DifferenceEngine.cpp
+++ /dev/null
@@ -1,874 +0,0 @@
-//===-- DifferenceEngine.cpp - Structural function/module comparison ------===//
-//
-// 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 header defines the implementation of the LLVM difference
-// engine, which structurally compares global values within a module.
-//
-//===----------------------------------------------------------------------===//
-
-#include "DifferenceEngine.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/DenseSet.h"
-#include "llvm/ADT/SmallString.h"
-#include "llvm/ADT/SmallVector.h"
-#include "llvm/ADT/StringSet.h"
-#include "llvm/IR/CFG.h"
-#include "llvm/IR/Constants.h"
-#include "llvm/IR/Function.h"
-#include "llvm/IR/Instructions.h"
-#include "llvm/IR/Module.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/raw_ostream.h"
-#include "llvm/Support/type_traits.h"
-#include <utility>
-
-using namespace llvm;
-
-namespace {
-
-/// A priority queue, implemented as a heap.
-template <class T, class Sorter, unsigned InlineCapacity>
-class PriorityQueue {
-  Sorter Precedes;
-  llvm::SmallVector<T, InlineCapacity> Storage;
-
-public:
-  PriorityQueue(const Sorter &Precedes) : Precedes(Precedes) {}
-
-  /// Checks whether the heap is empty.
-  bool empty() const { return Storage.empty(); }
-
-  /// Insert a new value on the heap.
-  void insert(const T &V) {
-    unsigned Index = Storage.size();
-    Storage.push_back(V);
-    if (Index == 0) return;
-
-    T *data = Storage.data();
-    while (true) {
-      unsigned Target = (Index + 1) / 2 - 1;
-      if (!Precedes(data[Index], data[Target])) return;
-      std::swap(data[Index], data[Target]);
-      if (Target == 0) return;
-      Index = Target;
-    }
-  }
-
-  /// Remove the minimum value in the heap.  Only valid on a non-empty heap.
-  T remove_min() {
-    assert(!empty());
-    T tmp = Storage[0];
-    
-    unsigned NewSize = Storage.size() - 1;
-    if (NewSize) {
-      // Move the slot at the end to the beginning.
-      if (std::is_trivially_copyable<T>::value)
-        Storage[0] = Storage[NewSize];
-      else
-        std::swap(Storage[0], Storage[NewSize]);
-
-      // Bubble the root up as necessary.
-      unsigned Index = 0;
-      while (true) {
-        // With a 1-based index, the children would be Index*2 and Index*2+1.
-        unsigned R = (Index + 1) * 2;
-        unsigned L = R - 1;
-
-        // If R is out of bounds, we're done after this in any case.
-        if (R >= NewSize) {
-          // If L is also out of bounds, we're done immediately.
-          if (L >= NewSize) break;
-
-          // Otherwise, test whether we should swap L and Index.
-          if (Precedes(Storage[L], Storage[Index]))
-            std::swap(Storage[L], Storage[Index]);
-          break;
-        }
-
-        // Otherwise, we need to compare with the smaller of L and R.
-        // Prefer R because it's closer to the end of the array.
-        unsigned IndexToTest = (Precedes(Storage[L], Storage[R]) ? L : R);
-
-        // If Index is >= the min of L and R, then heap ordering is restored.
-        if (!Precedes(Storage[IndexToTest], Storage[Index]))
-          break;
-
-        // Otherwise, keep bubbling up.
-        std::swap(Storage[IndexToTest], Storage[Index]);
-        Index = IndexToTest;
-      }
-    }
-    Storage.pop_back();
-
-    return tmp;
-  }
-};
-
-/// A function-scope difference engine.
-class FunctionDifferenceEngine {
-  DifferenceEngine &Engine;
-
-  // Some initializers may reference the variable we're currently checking. This
-  // can cause an infinite loop. The Saved[LR]HS ivars can be checked to prevent
-  // recursing.
-  const Value *SavedLHS;
-  const Value *SavedRHS;
-
-  /// The current mapping from old local values to new local values.
-  DenseMap<const Value *, const Value *> Values;
-
-  /// The current mapping from old blocks to new blocks.
-  DenseMap<const BasicBlock *, const BasicBlock *> Blocks;
-
-  DenseSet<std::pair<const Value *, const Value *>> TentativeValues;
-
-  unsigned getUnprocPredCount(const BasicBlock *Block) const {
-    unsigned Count = 0;
-    for (const_pred_iterator I = pred_begin(Block), E = pred_end(Block); I != E;
-         ++I)
-      if (!Blocks.count(*I)) Count++;
-    return Count;
-  }
-
-  typedef std::pair<const BasicBlock *, const BasicBlock *> BlockPair;
-
-  /// A type which sorts a priority queue by the number of unprocessed
-  /// predecessor blocks it has remaining.
-  ///
-  /// This is actually really expensive to calculate.
-  struct QueueSorter {
-    const FunctionDifferenceEngine &fde;
-    explicit QueueSorter(const FunctionDifferenceEngine &fde) : fde(fde) {}
-
-    bool operator()(BlockPair &Old, BlockPair &New) {
-      return fde.getUnprocPredCount(Old.first)
-           < fde.getUnprocPredCount(New.first);
-    }
-  };
-
-  /// A queue of unified blocks to process.
-  PriorityQueue<BlockPair, QueueSorter, 20> Queue;
-
-  /// Try to unify the given two blocks.  Enqueues them for processing
-  /// if they haven't already been processed.
-  ///
-  /// Returns true if there was a problem unifying them.
-  bool tryUnify(const BasicBlock *L, const BasicBlock *R) {
-    const BasicBlock *&Ref = Blocks[L];
-
-    if (Ref) {
-      if (Ref == R) return false;
-
-      Engine.logf("successor %l cannot be equivalent to %r; "
-                  "it's already equivalent to %r")
-        << L << R << Ref;
-      return true;
-    }
-
-    Ref = R;
-    Queue.insert(BlockPair(L, R));
-    return false;
-  }
-
-  /// Unifies two instructions, given that they're known not to have
-  /// structural differences.
-  void unify(const Instruction *L, const Instruction *R) {
-    DifferenceEngine::Context C(Engine, L, R);
-
-    bool Result = diff(L, R, true, true);
-    assert(!Result && "structural differences second time around?");
-    (void) Result;
-    if (!L->use_empty())
-      Values[L] = R;
-  }
-
-  void processQueue() {
-    while (!Queue.empty()) {
-      BlockPair Pair = Queue.remove_min();
-      diff(Pair.first, Pair.second);
-    }
-  }
-
-  void diff(const BasicBlock *L, const BasicBlock *R) {
-    DifferenceEngine::Context C(Engine, L, R);
-
-    BasicBlock::const_iterator LI = L->begin(), LE = L->end();
-    BasicBlock::const_iterator RI = R->begin();
-
-    do {
-      assert(LI != LE && RI != R->end());
-      const Instruction *LeftI = &*LI, *RightI = &*RI;
-
-      // If the instructions differ, start the more sophisticated diff
-      // algorithm at the start of the block.
-      if (diff(LeftI, RightI, false, false)) {
-        TentativeValues.clear();
-        return runBlockDiff(L->begin(), R->begin());
-      }
-
-      // Otherwise, tentatively unify them.
-      if (!LeftI->use_empty())
-        TentativeValues.insert(std::make_pair(LeftI, RightI));
-
-      ++LI;
-      ++RI;
-    } while (LI != LE); // This is sufficient: we can't get equality of
-                        // terminators if there are residual instructions.
-
-    // Unify everything in the block, non-tentatively this time.
-    TentativeValues.clear();
-    for (LI = L->begin(), RI = R->begin(); LI != LE; ++LI, ++RI)
-      unify(&*LI, &*RI);
-  }
-
-  bool matchForBlockDiff(const Instruction *L, const Instruction *R);
-  void runBlockDiff(BasicBlock::const_iterator LI,
-                    BasicBlock::const_iterator RI);
-
-  bool diffCallSites(const CallBase &L, const CallBase &R, bool Complain) {
-    // FIXME: call attributes
-    if (!equivalentAsOperands(L.getCalledOperand(), R.getCalledOperand())) {
-      if (Complain) Engine.log("called functions differ");
-      return true;
-    }
-    if (L.arg_size() != R.arg_size()) {
-      if (Complain) Engine.log("argument counts differ");
-      return true;
-    }
-    for (unsigned I = 0, E = L.arg_size(); I != E; ++I)
-      if (!equivalentAsOperands(L.getArgOperand(I), R.getArgOperand(I))) {
-        if (Complain)
-          Engine.logf("arguments %l and %r differ")
-              << L.getArgOperand(I) << R.getArgOperand(I);
-        return true;
-      }
-    return false;
-  }
-
-  bool diff(const Instruction *L, const Instruction *R, bool Complain,
-            bool TryUnify) {
-    // FIXME: metadata (if Complain is set)
-
-    // Different opcodes always imply different operations.
-    if (L->getOpcode() != R->getOpcode()) {
-      if (Complain) Engine.log("different instruction types");
-      return true;
-    }
-
-    if (isa<CmpInst>(L)) {
-      if (cast<CmpInst>(L)->getPredicate()
-            != cast<CmpInst>(R)->getPredicate()) {
-        if (Complain) Engine.log("different predicates");
-        return true;
-      }
-    } else if (isa<CallInst>(L)) {
-      return diffCallSites(cast<CallInst>(*L), cast<CallInst>(*R), Complain);
-    } else if (isa<PHINode>(L)) {
-      const PHINode &LI = cast<PHINode>(*L);
-      const PHINode &RI = cast<PHINode>(*R);
-
-      // This is really weird;  type uniquing is broken?
-      if (LI.getType() != RI.getType()) {
-        if (!LI.getType()->isPointerTy() || !RI.getType()->isPointerTy()) {
-          if (Complain) Engine.log("different phi types");
-          return true;
-        }
-      }
-
-      if (LI.getNumIncomingValues() != RI.getNumIncomingValues()) {
-        if (Complain)
-          Engine.log("PHI node # of incoming values differ");
-        return true;
-      }
-
-      for (unsigned I = 0; I < LI.getNumIncomingValues(); ++I) {
-        if (TryUnify)
-          tryUnify(LI.getIncomingBlock(I), RI.getIncomingBlock(I));
-
-        if (!equivalentAsOperands(LI.getIncomingValue(I),
-                                  RI.getIncomingValue(I))) {
-          if (Complain)
-            Engine.log("PHI node incoming values differ");
-          return true;
-        }
-      }
-
-      return false;
-
-    // Terminators.
-    } else if (isa<InvokeInst>(L)) {
-      const InvokeInst &LI = cast<InvokeInst>(*L);
-      const InvokeInst &RI = cast<InvokeInst>(*R);
-      if (diffCallSites(LI, RI, Complain))
-        return true;
-
-      if (TryUnify) {
-        tryUnify(LI.getNormalDest(), RI.getNormalDest());
-        tryUnify(LI.getUnwindDest(), RI.getUnwindDest());
-      }
-      return false;
-
-    } else if (isa<CallBrInst>(L)) {
-      const CallBrInst &LI = cast<CallBrInst>(*L);
-      const CallBrInst &RI = cast<CallBrInst>(*R);
-      if (LI.getNumIndirectDests() != RI.getNumIndirectDests()) {
-        if (Complain)
-          Engine.log("callbr # of indirect destinations differ");
-        return true;
-      }
-
-      // Perform the "try unify" step so that we can equate the indirect
-      // destinations before checking the call site.
-      for (unsigned I = 0; I < LI.getNumIndirectDests(); I++)
-        tryUnify(LI.getIndirectDest(I), RI.getIndirectDest(I));
-
-      if (diffCallSites(LI, RI, Complain))
-        return true;
-
-      if (TryUnify)
-        tryUnify(LI.getDefaultDest(), RI.getDefaultDest());
-      return false;
-
-    } else if (isa<BranchInst>(L)) {
-      const BranchInst *LI = cast<BranchInst>(L);
-      const BranchInst *RI = cast<BranchInst>(R);
-      if (LI->isConditional() != RI->isConditional()) {
-        if (Complain) Engine.log("branch conditionality differs");
-        return true;
-      }
-
-      if (LI->isConditional()) {
-        if (!equivalentAsOperands(LI->getCondition(), RI->getCondition())) {
-          if (Complain) Engine.log("branch conditions differ");
-          return true;
-        }
-        if (TryUnify) tryUnify(LI->getSuccessor(1), RI->getSuccessor(1));
-      }
-      if (TryUnify) tryUnify(LI->getSuccessor(0), RI->getSuccessor(0));
-      return false;
-
-    } else if (isa<IndirectBrInst>(L)) {
-      const IndirectBrInst *LI = cast<IndirectBrInst>(L);
-      const IndirectBrInst *RI = cast<IndirectBrInst>(R);
-      if (LI->getNumDestinations() != RI->getNumDestinations()) {
-        if (Complain) Engine.log("indirectbr # of destinations differ");
-        return true;
-      }
-
-      if (!equivalentAsOperands(LI->getAddress(), RI->getAddress())) {
-        if (Complain) Engine.log("indirectbr addresses differ");
-        return true;
-      }
-
-      if (TryUnify) {
-        for (unsigned i = 0; i < LI->getNumDestinations(); i++) {
-          tryUnify(LI->getDestination(i), RI->getDestination(i));
-        }
-      }
-      return false;
-
-    } else if (isa<SwitchInst>(L)) {
-      const SwitchInst *LI = cast<SwitchInst>(L);
-      const SwitchInst *RI = cast<SwitchInst>(R);
-      if (!equivalentAsOperands(LI->getCondition(), RI->getCondition())) {
-        if (Complain) Engine.log("switch conditions differ");
-        return true;
-      }
-      if (TryUnify) tryUnify(LI->getDefaultDest(), RI->getDefaultDest());
-
-      bool Difference = false;
-
-      DenseMap<const ConstantInt *, const BasicBlock *> LCases;
-      for (auto Case : LI->cases())
-        LCases[Case.getCaseValue()] = Case.getCaseSuccessor();
-
-      for (auto Case : RI->cases()) {
-        const ConstantInt *CaseValue = Case.getCaseValue();
-        const BasicBlock *LCase = LCases[CaseValue];
-        if (LCase) {
-          if (TryUnify)
-            tryUnify(LCase, Case.getCaseSuccessor());
-          LCases.erase(CaseValue);
-        } else if (Complain || !Difference) {
-          if (Complain)
-            Engine.logf("right switch has extra case %r") << CaseValue;
-          Difference = true;
-        }
-      }
-      if (!Difference)
-        for (DenseMap<const ConstantInt *, const BasicBlock *>::iterator
-                 I = LCases.begin(),
-                 E = LCases.end();
-             I != E; ++I) {
-          if (Complain)
-            Engine.logf("left switch has extra case %l") << I->first;
-          Difference = true;
-        }
-      return Difference;
-    } else if (isa<UnreachableInst>(L)) {
-      return false;
-    }
-
-    if (L->getNumOperands() != R->getNumOperands()) {
-      if (Complain) Engine.log("instructions have different operand counts");
-      return true;
-    }
-
-    for (unsigned I = 0, E = L->getNumOperands(); I != E; ++I) {
-      Value *LO = L->getOperand(I), *RO = R->getOperand(I);
-      if (!equivalentAsOperands(LO, RO)) {
-        if (Complain) Engine.logf("operands %l and %r differ") << LO << RO;
-        return true;
-      }
-    }
-
-    return false;
-  }
-
-public:
-  bool equivalentAsOperands(const Constant *L, const Constant *R) {
-    // Use equality as a preliminary filter.
-    if (L == R)
-      return true;
-
-    if (L->getValueID() != R->getValueID())
-      return false;
-
-    // Ask the engine about global values.
-    if (isa<GlobalValue>(L))
-      return Engine.equivalentAsOperands(cast<GlobalValue>(L),
-                                         cast<GlobalValue>(R));
-
-    // Compare constant expressions structurally.
-    if (isa<ConstantExpr>(L))
-      return equivalentAsOperands(cast<ConstantExpr>(L),
-                                  cast<ConstantExpr>(R));
-
-    // Constants of the "same type" don't always actually have the same
-    // type; I don't know why.  Just white-list them.
-    if (isa<ConstantPointerNull>(L) || isa<UndefValue>(L) || isa<ConstantAggregateZero>(L))
-      return true;
-
-    // Block addresses only match if we've already encountered the
-    // block.  FIXME: tentative matches?
-    if (isa<BlockAddress>(L))
-      return Blocks[cast<BlockAddress>(L)->getBasicBlock()]
-                 == cast<BlockAddress>(R)->getBasicBlock();
-
-    // If L and R are ConstantVectors, compare each element
-    if (isa<ConstantVector>(L)) {
-      const ConstantVector *CVL = cast<ConstantVector>(L);
-      const ConstantVector *CVR = cast<ConstantVector>(R);
-      if (CVL->getType()->getNumElements() != CVR->getType()->getNumElements())
-        return false;
-      for (unsigned i = 0; i < CVL->getType()->getNumElements(); i++) {
-        if (!equivalentAsOperands(CVL->getOperand(i), CVR->getOperand(i)))
-          return false;
-      }
-      return true;
-    }
-
-    // If L and R are ConstantArrays, compare the element count and types.
-    if (isa<ConstantArray>(L)) {
-      const ConstantArray *CAL = cast<ConstantArray>(L);
-      const ConstantArray *CAR = cast<ConstantArray>(R);
-      // Sometimes a type may be equivalent, but not uniquified---e.g. it may
-      // contain a GEP instruction. Do a deeper comparison of the types.
-      if (CAL->getType()->getNumElements() != CAR->getType()->getNumElements())
-        return false;
-
-      for (unsigned I = 0; I < CAL->getType()->getNumElements(); ++I) {
-        if (!equivalentAsOperands(CAL->getAggregateElement(I),
-                                  CAR->getAggregateElement(I)))
-          return false;
-      }
-
-      return true;
-    }
-
-    // If L and R are ConstantStructs, compare each field and type.
-    if (isa<ConstantStruct>(L)) {
-      const ConstantStruct *CSL = cast<ConstantStruct>(L);
-      const ConstantStruct *CSR = cast<ConstantStruct>(R);
-
-      const StructType *LTy = cast<StructType>(CSL->getType());
-      const StructType *RTy = cast<StructType>(CSR->getType());
-
-      // The StructTypes should have the same attributes. Don't use
-      // isLayoutIdentical(), because that just checks the element pointers,
-      // which may not work here.
-      if (LTy->getNumElements() != RTy->getNumElements() ||
-          LTy->isPacked() != RTy->isPacked())
-        return false;
-
-      for (unsigned I = 0; I < LTy->getNumElements(); I++) {
-        const Value *LAgg = CSL->getAggregateElement(I);
-        const Value *RAgg = CSR->getAggregateElement(I);
-
-        if (LAgg == SavedLHS || RAgg == SavedRHS) {
-          if (LAgg != SavedLHS || RAgg != SavedRHS)
-            // If the left and right operands aren't both re-analyzing the
-            // variable, then the initialiers don't match, so report "false".
-            // Otherwise, we skip these operands..
-            return false;
-
-          continue;
-        }
-
-        if (!equivalentAsOperands(LAgg, RAgg)) {
-          return false;
-        }
-      }
-
-      return true;
-    }
-
-    return false;
-  }
-
-  bool equivalentAsOperands(const ConstantExpr *L, const ConstantExpr *R) {
-    if (L == R)
-      return true;
-
-    if (L->getOpcode() != R->getOpcode())
-      return false;
-
-    switch (L->getOpcode()) {
-    case Instruction::ICmp:
-    case Instruction::FCmp:
-      if (L->getPredicate() != R->getPredicate())
-        return false;
-      break;
-
-    case Instruction::GetElementPtr:
-      // FIXME: inbounds?
-      break;
-
-    default:
-      break;
-    }
-
-    if (L->getNumOperands() != R->getNumOperands())
-      return false;
-
-    for (unsigned I = 0, E = L->getNumOperands(); I != E; ++I) {
-      const auto *LOp = L->getOperand(I);
-      const auto *ROp = R->getOperand(I);
-
-      if (LOp == SavedLHS || ROp == SavedRHS) {
-        if (LOp != SavedLHS || ROp != SavedRHS)
-          // If the left and right operands aren't both re-analyzing the
-          // variable, then the initialiers don't match, so report "false".
-          // Otherwise, we skip these operands..
-          return false;
-
-        continue;
-      }
-
-      if (!equivalentAsOperands(LOp, ROp))
-        return false;
-    }
-
-    return true;
-  }
-
-  bool equivalentAsOperands(const Value *L, const Value *R) {
-    // Fall out if the values have different kind.
-    // This possibly shouldn't take priority over oracles.
-    if (L->getValueID() != R->getValueID())
-      return false;
-
-    // Value subtypes:  Argument, Constant, Instruction, BasicBlock,
-    //                  InlineAsm, MDNode, MDString, PseudoSourceValue
-
-    if (isa<Constant>(L))
-      return equivalentAsOperands(cast<Constant>(L), cast<Constant>(R));
-
-    if (isa<Instruction>(L))
-      return Values[L] == R || TentativeValues.count(std::make_pair(L, R));
-
-    if (isa<Argument>(L))
-      return Values[L] == R;
-
-    if (isa<BasicBlock>(L))
-      return Blocks[cast<BasicBlock>(L)] != R;
-
-    // Pretend everything else is identical.
-    return true;
-  }
-
-  // Avoid a gcc warning about accessing 'this' in an initializer.
-  FunctionDifferenceEngine *this_() { return this; }
-
-public:
-  FunctionDifferenceEngine(DifferenceEngine &Engine,
-                           const Value *SavedLHS = nullptr,
-                           const Value *SavedRHS = nullptr)
-      : Engine(Engine), SavedLHS(SavedLHS), SavedRHS(SavedRHS),
-        Queue(QueueSorter(*this_())) {}
-
-  void diff(const Function *L, const Function *R) {
-    if (L->arg_size() != R->arg_size())
-      Engine.log("different argument counts");
-
-    // Map the arguments.
-    for (Function::const_arg_iterator LI = L->arg_begin(), LE = L->arg_end(),
-                                      RI = R->arg_begin(), RE = R->arg_end();
-         LI != LE && RI != RE; ++LI, ++RI)
-      Values[&*LI] = &*RI;
-
-    tryUnify(&*L->begin(), &*R->begin());
-    processQueue();
-  }
-};
-
-struct DiffEntry {
-  DiffEntry() : Cost(0) {}
-
-  unsigned Cost;
-  llvm::SmallVector<char, 8> Path; // actually of DifferenceEngine::DiffChange
-};
-
-bool FunctionDifferenceEngine::matchForBlockDiff(const Instruction *L,
-                                                 const Instruction *R) {
-  return !diff(L, R, false, false);
-}
-
-void FunctionDifferenceEngine::runBlockDiff(BasicBlock::const_iterator LStart,
-                                            BasicBlock::const_iterator RStart) {
-  BasicBlock::const_iterator LE = LStart->getParent()->end();
-  BasicBlock::const_iterator RE = RStart->getParent()->end();
-
-  unsigned NL = std::distance(LStart, LE);
-
-  SmallVector<DiffEntry, 20> Paths1(NL+1);
-  SmallVector<DiffEntry, 20> Paths2(NL+1);
-
-  DiffEntry *Cur = Paths1.data();
-  DiffEntry *Next = Paths2.data();
-
-  const unsigned LeftCost = 2;
-  const unsigned RightCost = 2;
-  const unsigned MatchCost = 0;
-
-  assert(TentativeValues.empty());
-
-  // Initialize the first column.
-  for (unsigned I = 0; I != NL+1; ++I) {
-    Cur[I].Cost = I * LeftCost;
-    for (unsigned J = 0; J != I; ++J)
-      Cur[I].Path.push_back(DC_left);
-  }
-
-  for (BasicBlock::const_iterator RI = RStart; RI != RE; ++RI) {
-    // Initialize the first row.
-    Next[0] = Cur[0];
-    Next[0].Cost += RightCost;
-    Next[0].Path.push_back(DC_right);
-
-    unsigned Index = 1;
-    for (BasicBlock::const_iterator LI = LStart; LI != LE; ++LI, ++Index) {
-      if (matchForBlockDiff(&*LI, &*RI)) {
-        Next[Index] = Cur[Index-1];
-        Next[Index].Cost += MatchCost;
-        Next[Index].Path.push_back(DC_match);
-        TentativeValues.insert(std::make_pair(&*LI, &*RI));
-      } else if (Next[Index-1].Cost <= Cur[Index].Cost) {
-        Next[Index] = Next[Index-1];
-        Next[Index].Cost += LeftCost;
-        Next[Index].Path.push_back(DC_left);
-      } else {
-        Next[Index] = Cur[Index];
-        Next[Index].Cost += RightCost;
-        Next[Index].Path.push_back(DC_right);
-      }
-    }
-
-    std::swap(Cur, Next);
-  }
-
-  // We don't need the tentative values anymore; everything from here
-  // on out should be non-tentative.
-  TentativeValues.clear();
-
-  SmallVectorImpl<char> &Path = Cur[NL].Path;
-  BasicBlock::const_iterator LI = LStart, RI = RStart;
-
-  DiffLogBuilder Diff(Engine.getConsumer());
-
-  // Drop trailing matches.
-  while (Path.size() && Path.back() == DC_match)
-    Path.pop_back();
-
-  // Skip leading matches.
-  SmallVectorImpl<char>::iterator
-    PI = Path.begin(), PE = Path.end();
-  while (PI != PE && *PI == DC_match) {
-    unify(&*LI, &*RI);
-    ++PI;
-    ++LI;
-    ++RI;
-  }
-
-  for (; PI != PE; ++PI) {
-    switch (static_cast<DiffChange>(*PI)) {
-    case DC_match:
-      assert(LI != LE && RI != RE);
-      {
-        const Instruction *L = &*LI, *R = &*RI;
-        unify(L, R);
-        Diff.addMatch(L, R);
-      }
-      ++LI; ++RI;
-      break;
-
-    case DC_left:
-      assert(LI != LE);
-      Diff.addLeft(&*LI);
-      ++LI;
-      break;
-
-    case DC_right:
-      assert(RI != RE);
-      Diff.addRight(&*RI);
-      ++RI;
-      break;
-    }
-  }
-
-  // Finishing unifying and complaining about the tails of the block,
-  // which should be matches all the way through.
-  while (LI != LE) {
-    assert(RI != RE);
-    unify(&*LI, &*RI);
-    ++LI;
-    ++RI;
-  }
-
-  // If the terminators have different kinds, but one is an invoke and the
-  // other is an unconditional branch immediately following a call, unify
-  // the results and the destinations.
-  const Instruction *LTerm = LStart->getParent()->getTerminator();
-  const Instruction *RTerm = RStart->getParent()->getTerminator();
-  if (isa<BranchInst>(LTerm) && isa<InvokeInst>(RTerm)) {
-    if (cast<BranchInst>(LTerm)->isConditional()) return;
-    BasicBlock::const_iterator I = LTerm->getIterator();
-    if (I == LStart->getParent()->begin()) return;
-    --I;
-    if (!isa<CallInst>(*I)) return;
-    const CallInst *LCall = cast<CallInst>(&*I);
-    const InvokeInst *RInvoke = cast<InvokeInst>(RTerm);
-    if (!equivalentAsOperands(LCall->getCalledOperand(),
-                              RInvoke->getCalledOperand()))
-      return;
-    if (!LCall->use_empty())
-      Values[LCall] = RInvoke;
-    tryUnify(LTerm->getSuccessor(0), RInvoke->getNormalDest());
-  } else if (isa<InvokeInst>(LTerm) && isa<BranchInst>(RTerm)) {
-    if (cast<BranchInst>(RTerm)->isConditional()) return;
-    BasicBlock::const_iterator I = RTerm->getIterator();
-    if (I == RStart->getParent()->begin()) return;
-    --I;
-    if (!isa<CallInst>(*I)) return;
-    const CallInst *RCall = cast<CallInst>(I);
-    const InvokeInst *LInvoke = cast<InvokeInst>(LTerm);
-    if (!equivalentAsOperands(LInvoke->getCalledOperand(),
-                              RCall->getCalledOperand()))
-      return;
-    if (!LInvoke->use_empty())
-      Values[LInvoke] = RCall;
-    tryUnify(LInvoke->getNormalDest(), RTerm->getSuccessor(0));
-  }
-}
-}
-
-void DifferenceEngine::Oracle::anchor() { }
-
-void DifferenceEngine::diff(const Function *L, const Function *R) {
-  Context C(*this, L, R);
-
-  // FIXME: types
-  // FIXME: attributes and CC
-  // FIXME: parameter attributes
-  
-  // If both are declarations, we're done.
-  if (L->empty() && R->empty())
-    return;
-  else if (L->empty())
-    log("left function is declaration, right function is definition");
-  else if (R->empty())
-    log("right function is declaration, left function is definition");
-  else
-    FunctionDifferenceEngine(*this).diff(L, R);
-}
-
-void DifferenceEngine::diff(const Module *L, const Module *R) {
-  StringSet<> LNames;
-  SmallVector<std::pair<const Function *, const Function *>, 20> Queue;
-
-  unsigned LeftAnonCount = 0;
-  unsigned RightAnonCount = 0;
-
-  for (Module::const_iterator I = L->begin(), E = L->end(); I != E; ++I) {
-    const Function *LFn = &*I;
-    StringRef Name = LFn->getName();
-    if (Name.empty()) {
-      ++LeftAnonCount;
-      continue;
-    }
-
-    LNames.insert(Name);
-
-    if (Function *RFn = R->getFunction(LFn->getName()))
-      Queue.push_back(std::make_pair(LFn, RFn));
-    else
-      logf("function %l exists only in left module") << LFn;
-  }
-
-  for (Module::const_iterator I = R->begin(), E = R->end(); I != E; ++I) {
-    const Function *RFn = &*I;
-    StringRef Name = RFn->getName();
-    if (Name.empty()) {
-      ++RightAnonCount;
-      continue;
-    }
-
-    if (!LNames.count(Name))
-      logf("function %r exists only in right module") << RFn;
-  }
-
-  if (LeftAnonCount != 0 || RightAnonCount != 0) {
-    SmallString<32> Tmp;
-    logf(("not comparing " + Twine(LeftAnonCount) +
-          " anonymous functions in the left module and " +
-          Twine(RightAnonCount) + " in the right module")
-             .toStringRef(Tmp));
-  }
-
-  for (SmallVectorImpl<std::pair<const Function *, const Function *>>::iterator
-           I = Queue.begin(),
-           E = Queue.end();
-       I != E; ++I)
-    diff(I->first, I->second);
-}
-
-bool DifferenceEngine::equivalentAsOperands(const GlobalValue *L,
-                                            const GlobalValue *R) {
-  if (globalValueOracle) return (*globalValueOracle)(L, R);
-
-  if (isa<GlobalVariable>(L) && isa<GlobalVariable>(R)) {
-    const GlobalVariable *GVL = cast<GlobalVariable>(L);
-    const GlobalVariable *GVR = cast<GlobalVariable>(R);
-    if (GVL->hasLocalLinkage() && GVL->hasUniqueInitializer() &&
-        GVR->hasLocalLinkage() && GVR->hasUniqueInitializer())
-      return FunctionDifferenceEngine(*this, GVL, GVR)
-          .equivalentAsOperands(GVL->getInitializer(), GVR->getInitializer());
-  }
-
-  return L->getName() == R->getName();
-}