//
// Limitations and TODO items:
//
-// 1) We only considers n-ary adds for now. This should be extended and
-// generalized.
-//
-// 2) Besides arithmetic operations, similar reassociation can be applied to
-// GEPs. For example, if
-// X = &arr[a]
-// dominates
-// Y = &arr[a + b]
-// we may rewrite Y into X + b.
+// 1) We only considers n-ary adds and muls for now. This should be extended
+// and generalized.
//
//===----------------------------------------------------------------------===//
+#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PatternMatch.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
initializeNaryReassociatePass(*PassRegistry::getPassRegistry());
}
+ bool doInitialization(Module &M) override {
+ DL = &M.getDataLayout();
+ return false;
+ }
bool runOnFunction(Function &F) override;
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addPreserved<DominatorTreeWrapperPass>();
- AU.addPreserved<ScalarEvolution>();
+ AU.addPreserved<ScalarEvolutionWrapperPass>();
AU.addPreserved<TargetLibraryInfoWrapperPass>();
+ AU.addRequired<AssumptionCacheTracker>();
AU.addRequired<DominatorTreeWrapperPass>();
- AU.addRequired<ScalarEvolution>();
+ AU.addRequired<ScalarEvolutionWrapperPass>();
AU.addRequired<TargetLibraryInfoWrapperPass>();
+ AU.addRequired<TargetTransformInfoWrapperPass>();
AU.setPreservesCFG();
}
// Runs only one iteration of the dominator-based algorithm. See the header
// comments for why we need multiple iterations.
bool doOneIteration(Function &F);
- // Reasssociates I to a better form.
- Instruction *tryReassociateAdd(Instruction *I);
- // A helper function for tryReassociateAdd. LHS and RHS are explicitly passed.
- Instruction *tryReassociateAdd(Value *LHS, Value *RHS, Instruction *I);
- // Rewrites I to LHS + RHS if LHS is computed already.
- Instruction *tryReassociatedAdd(const SCEV *LHS, Value *RHS, Instruction *I);
+ // Reassociates I for better CSE.
+ Instruction *tryReassociate(Instruction *I);
+
+ // Reassociate GEP for better CSE.
+ Instruction *tryReassociateGEP(GetElementPtrInst *GEP);
+ // Try splitting GEP at the I-th index and see whether either part can be
+ // CSE'ed. This is a helper function for tryReassociateGEP.
+ //
+ // \p IndexedType The element type indexed by GEP's I-th index. This is
+ // equivalent to
+ // GEP->getIndexedType(GEP->getPointerOperand(), 0-th index,
+ // ..., i-th index).
+ GetElementPtrInst *tryReassociateGEPAtIndex(GetElementPtrInst *GEP,
+ unsigned I, Type *IndexedType);
+ // Given GEP's I-th index = LHS + RHS, see whether &Base[..][LHS][..] or
+ // &Base[..][RHS][..] can be CSE'ed and rewrite GEP accordingly.
+ GetElementPtrInst *tryReassociateGEPAtIndex(GetElementPtrInst *GEP,
+ unsigned I, Value *LHS,
+ Value *RHS, Type *IndexedType);
+
+ // Reassociate binary operators for better CSE.
+ Instruction *tryReassociateBinaryOp(BinaryOperator *I);
+
+ // A helper function for tryReassociateBinaryOp. LHS and RHS are explicitly
+ // passed.
+ Instruction *tryReassociateBinaryOp(Value *LHS, Value *RHS,
+ BinaryOperator *I);
+ // Rewrites I to (LHS op RHS) if LHS is computed already.
+ Instruction *tryReassociatedBinaryOp(const SCEV *LHS, Value *RHS,
+ BinaryOperator *I);
+
+ // Tries to match Op1 and Op2 by using V.
+ bool matchTernaryOp(BinaryOperator *I, Value *V, Value *&Op1, Value *&Op2);
+
+ // Gets SCEV for (LHS op RHS).
+ const SCEV *getBinarySCEV(BinaryOperator *I, const SCEV *LHS,
+ const SCEV *RHS);
+
+ // Returns the closest dominator of \c Dominatee that computes
+ // \c CandidateExpr. Returns null if not found.
+ Instruction *findClosestMatchingDominator(const SCEV *CandidateExpr,
+ Instruction *Dominatee);
+ // GetElementPtrInst implicitly sign-extends an index if the index is shorter
+ // than the pointer size. This function returns whether Index is shorter than
+ // GEP's pointer size, i.e., whether Index needs to be sign-extended in order
+ // to be an index of GEP.
+ bool requiresSignExtension(Value *Index, GetElementPtrInst *GEP);
+
+ AssumptionCache *AC;
+ const DataLayout *DL;
DominatorTree *DT;
ScalarEvolution *SE;
TargetLibraryInfo *TLI;
+ TargetTransformInfo *TTI;
// A lookup table quickly telling which instructions compute the given SCEV.
// Note that there can be multiple instructions at different locations
// computing to the same SCEV, so we map a SCEV to an instruction list. For
// foo(a + b);
// if (p2)
// bar(a + b);
- DenseMap<const SCEV *, SmallVector<Instruction *, 2>> SeenExprs;
+ DenseMap<const SCEV *, SmallVector<WeakVH, 2>> SeenExprs;
};
} // anonymous namespace
char NaryReassociate::ID = 0;
INITIALIZE_PASS_BEGIN(NaryReassociate, "nary-reassociate", "Nary reassociation",
false, false)
+INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(ScalarEvolution)
+INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
+INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
INITIALIZE_PASS_END(NaryReassociate, "nary-reassociate", "Nary reassociation",
false, false)
if (skipOptnoneFunction(F))
return false;
+ AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
- SE = &getAnalysis<ScalarEvolution>();
+ SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
+ TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
bool Changed = false, ChangedInThisIteration;
do {
return Changed;
}
+// Whitelist the instruction types NaryReassociate handles for now.
+static bool isPotentiallyNaryReassociable(Instruction *I) {
+ switch (I->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::GetElementPtr:
+ case Instruction::Mul:
+ return true;
+ default:
+ return false;
+ }
+}
+
bool NaryReassociate::doOneIteration(Function &F) {
bool Changed = false;
SeenExprs.clear();
- // Traverse the dominator tree in the depth-first order. This order makes sure
- // all bases of a candidate are in Candidates when we process it.
+ // Process the basic blocks in pre-order of the dominator tree. This order
+ // ensures that all bases of a candidate are in Candidates when we process it.
for (auto Node = GraphTraits<DominatorTree *>::nodes_begin(DT);
Node != GraphTraits<DominatorTree *>::nodes_end(DT); ++Node) {
BasicBlock *BB = Node->getBlock();
for (auto I = BB->begin(); I != BB->end(); ++I) {
- if (I->getOpcode() == Instruction::Add) {
- if (Instruction *NewI = tryReassociateAdd(I)) {
+ if (SE->isSCEVable(I->getType()) && isPotentiallyNaryReassociable(&*I)) {
+ const SCEV *OldSCEV = SE->getSCEV(&*I);
+ if (Instruction *NewI = tryReassociate(&*I)) {
Changed = true;
- SE->forgetValue(I);
+ SE->forgetValue(&*I);
I->replaceAllUsesWith(NewI);
- RecursivelyDeleteTriviallyDeadInstructions(I, TLI);
- I = NewI;
+ // If SeenExprs constains I's WeakVH, that entry will be replaced with
+ // nullptr.
+ RecursivelyDeleteTriviallyDeadInstructions(&*I, TLI);
+ I = NewI->getIterator();
}
- // We should add the rewritten instruction because tryReassociateAdd may
- // have invalidated the original one.
- SeenExprs[SE->getSCEV(I)].push_back(I);
+ // Add the rewritten instruction to SeenExprs; the original instruction
+ // is deleted.
+ const SCEV *NewSCEV = SE->getSCEV(&*I);
+ SeenExprs[NewSCEV].push_back(WeakVH(&*I));
+ // Ideally, NewSCEV should equal OldSCEV because tryReassociate(I)
+ // is equivalent to I. However, ScalarEvolution::getSCEV may
+ // weaken nsw causing NewSCEV not to equal OldSCEV. For example, suppose
+ // we reassociate
+ // I = &a[sext(i +nsw j)] // assuming sizeof(a[0]) = 4
+ // to
+ // NewI = &a[sext(i)] + sext(j).
+ //
+ // ScalarEvolution computes
+ // getSCEV(I) = a + 4 * sext(i + j)
+ // getSCEV(newI) = a + 4 * sext(i) + 4 * sext(j)
+ // which are different SCEVs.
+ //
+ // To alleviate this issue of ScalarEvolution not always capturing
+ // equivalence, we add I to SeenExprs[OldSCEV] as well so that we can
+ // map both SCEV before and after tryReassociate(I) to I.
+ //
+ // This improvement is exercised in @reassociate_gep_nsw in nary-gep.ll.
+ if (NewSCEV != OldSCEV)
+ SeenExprs[OldSCEV].push_back(WeakVH(&*I));
}
}
}
return Changed;
}
-Instruction *NaryReassociate::tryReassociateAdd(Instruction *I) {
+Instruction *NaryReassociate::tryReassociate(Instruction *I) {
+ switch (I->getOpcode()) {
+ case Instruction::Add:
+ case Instruction::Mul:
+ return tryReassociateBinaryOp(cast<BinaryOperator>(I));
+ case Instruction::GetElementPtr:
+ return tryReassociateGEP(cast<GetElementPtrInst>(I));
+ default:
+ llvm_unreachable("should be filtered out by isPotentiallyNaryReassociable");
+ }
+}
+
+// FIXME: extract this method into TTI->getGEPCost.
+static bool isGEPFoldable(GetElementPtrInst *GEP,
+ const TargetTransformInfo *TTI,
+ const DataLayout *DL) {
+ GlobalVariable *BaseGV = nullptr;
+ int64_t BaseOffset = 0;
+ bool HasBaseReg = false;
+ int64_t Scale = 0;
+
+ if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getPointerOperand()))
+ BaseGV = GV;
+ else
+ HasBaseReg = true;
+
+ gep_type_iterator GTI = gep_type_begin(GEP);
+ for (auto I = GEP->idx_begin(); I != GEP->idx_end(); ++I, ++GTI) {
+ if (isa<SequentialType>(*GTI)) {
+ int64_t ElementSize = DL->getTypeAllocSize(GTI.getIndexedType());
+ if (ConstantInt *ConstIdx = dyn_cast<ConstantInt>(*I)) {
+ BaseOffset += ConstIdx->getSExtValue() * ElementSize;
+ } else {
+ // Needs scale register.
+ if (Scale != 0) {
+ // No addressing mode takes two scale registers.
+ return false;
+ }
+ Scale = ElementSize;
+ }
+ } else {
+ StructType *STy = cast<StructType>(*GTI);
+ uint64_t Field = cast<ConstantInt>(*I)->getZExtValue();
+ BaseOffset += DL->getStructLayout(STy)->getElementOffset(Field);
+ }
+ }
+
+ unsigned AddrSpace = GEP->getPointerAddressSpace();
+ return TTI->isLegalAddressingMode(GEP->getType()->getElementType(), BaseGV,
+ BaseOffset, HasBaseReg, Scale, AddrSpace);
+}
+
+Instruction *NaryReassociate::tryReassociateGEP(GetElementPtrInst *GEP) {
+ // Not worth reassociating GEP if it is foldable.
+ if (isGEPFoldable(GEP, TTI, DL))
+ return nullptr;
+
+ gep_type_iterator GTI = gep_type_begin(*GEP);
+ for (unsigned I = 1, E = GEP->getNumOperands(); I != E; ++I) {
+ if (isa<SequentialType>(*GTI++)) {
+ if (auto *NewGEP = tryReassociateGEPAtIndex(GEP, I - 1, *GTI)) {
+ return NewGEP;
+ }
+ }
+ }
+ return nullptr;
+}
+
+bool NaryReassociate::requiresSignExtension(Value *Index,
+ GetElementPtrInst *GEP) {
+ unsigned PointerSizeInBits =
+ DL->getPointerSizeInBits(GEP->getType()->getPointerAddressSpace());
+ return cast<IntegerType>(Index->getType())->getBitWidth() < PointerSizeInBits;
+}
+
+GetElementPtrInst *
+NaryReassociate::tryReassociateGEPAtIndex(GetElementPtrInst *GEP, unsigned I,
+ Type *IndexedType) {
+ Value *IndexToSplit = GEP->getOperand(I + 1);
+ if (SExtInst *SExt = dyn_cast<SExtInst>(IndexToSplit)) {
+ IndexToSplit = SExt->getOperand(0);
+ } else if (ZExtInst *ZExt = dyn_cast<ZExtInst>(IndexToSplit)) {
+ // zext can be treated as sext if the source is non-negative.
+ if (isKnownNonNegative(ZExt->getOperand(0), *DL, 0, AC, GEP, DT))
+ IndexToSplit = ZExt->getOperand(0);
+ }
+
+ if (AddOperator *AO = dyn_cast<AddOperator>(IndexToSplit)) {
+ // If the I-th index needs sext and the underlying add is not equipped with
+ // nsw, we cannot split the add because
+ // sext(LHS + RHS) != sext(LHS) + sext(RHS).
+ if (requiresSignExtension(IndexToSplit, GEP) &&
+ computeOverflowForSignedAdd(AO, *DL, AC, GEP, DT) !=
+ OverflowResult::NeverOverflows)
+ return nullptr;
+
+ Value *LHS = AO->getOperand(0), *RHS = AO->getOperand(1);
+ // IndexToSplit = LHS + RHS.
+ if (auto *NewGEP = tryReassociateGEPAtIndex(GEP, I, LHS, RHS, IndexedType))
+ return NewGEP;
+ // Symmetrically, try IndexToSplit = RHS + LHS.
+ if (LHS != RHS) {
+ if (auto *NewGEP =
+ tryReassociateGEPAtIndex(GEP, I, RHS, LHS, IndexedType))
+ return NewGEP;
+ }
+ }
+ return nullptr;
+}
+
+GetElementPtrInst *NaryReassociate::tryReassociateGEPAtIndex(
+ GetElementPtrInst *GEP, unsigned I, Value *LHS, Value *RHS,
+ Type *IndexedType) {
+ // Look for GEP's closest dominator that has the same SCEV as GEP except that
+ // the I-th index is replaced with LHS.
+ SmallVector<const SCEV *, 4> IndexExprs;
+ for (auto Index = GEP->idx_begin(); Index != GEP->idx_end(); ++Index)
+ IndexExprs.push_back(SE->getSCEV(*Index));
+ // Replace the I-th index with LHS.
+ IndexExprs[I] = SE->getSCEV(LHS);
+ if (isKnownNonNegative(LHS, *DL, 0, AC, GEP, DT) &&
+ DL->getTypeSizeInBits(LHS->getType()) <
+ DL->getTypeSizeInBits(GEP->getOperand(I)->getType())) {
+ // Zero-extend LHS if it is non-negative. InstCombine canonicalizes sext to
+ // zext if the source operand is proved non-negative. We should do that
+ // consistently so that CandidateExpr more likely appears before. See
+ // @reassociate_gep_assume for an example of this canonicalization.
+ IndexExprs[I] =
+ SE->getZeroExtendExpr(IndexExprs[I], GEP->getOperand(I)->getType());
+ }
+ const SCEV *CandidateExpr = SE->getGEPExpr(
+ GEP->getSourceElementType(), SE->getSCEV(GEP->getPointerOperand()),
+ IndexExprs, GEP->isInBounds());
+
+ auto *Candidate = findClosestMatchingDominator(CandidateExpr, GEP);
+ if (Candidate == nullptr)
+ return nullptr;
+
+ PointerType *TypeOfCandidate = dyn_cast<PointerType>(Candidate->getType());
+ // Pretty rare but theoretically possible when a numeric value happens to
+ // share CandidateExpr.
+ if (TypeOfCandidate == nullptr)
+ return nullptr;
+
+ // NewGEP = (char *)Candidate + RHS * sizeof(IndexedType)
+ uint64_t IndexedSize = DL->getTypeAllocSize(IndexedType);
+ Type *ElementType = TypeOfCandidate->getElementType();
+ uint64_t ElementSize = DL->getTypeAllocSize(ElementType);
+ // Another less rare case: because I is not necessarily the last index of the
+ // GEP, the size of the type at the I-th index (IndexedSize) is not
+ // necessarily divisible by ElementSize. For example,
+ //
+ // #pragma pack(1)
+ // struct S {
+ // int a[3];
+ // int64 b[8];
+ // };
+ // #pragma pack()
+ //
+ // sizeof(S) = 100 is indivisible by sizeof(int64) = 8.
+ //
+ // TODO: bail out on this case for now. We could emit uglygep.
+ if (IndexedSize % ElementSize != 0)
+ return nullptr;
+
+ // NewGEP = &Candidate[RHS * (sizeof(IndexedType) / sizeof(Candidate[0])));
+ IRBuilder<> Builder(GEP);
+ Type *IntPtrTy = DL->getIntPtrType(TypeOfCandidate);
+ if (RHS->getType() != IntPtrTy)
+ RHS = Builder.CreateSExtOrTrunc(RHS, IntPtrTy);
+ if (IndexedSize != ElementSize) {
+ RHS = Builder.CreateMul(
+ RHS, ConstantInt::get(IntPtrTy, IndexedSize / ElementSize));
+ }
+ GetElementPtrInst *NewGEP =
+ cast<GetElementPtrInst>(Builder.CreateGEP(Candidate, RHS));
+ NewGEP->setIsInBounds(GEP->isInBounds());
+ NewGEP->takeName(GEP);
+ return NewGEP;
+}
+
+Instruction *NaryReassociate::tryReassociateBinaryOp(BinaryOperator *I) {
Value *LHS = I->getOperand(0), *RHS = I->getOperand(1);
- if (auto *NewI = tryReassociateAdd(LHS, RHS, I))
+ if (auto *NewI = tryReassociateBinaryOp(LHS, RHS, I))
return NewI;
- if (auto *NewI = tryReassociateAdd(RHS, LHS, I))
+ if (auto *NewI = tryReassociateBinaryOp(RHS, LHS, I))
return NewI;
return nullptr;
}
-Instruction *NaryReassociate::tryReassociateAdd(Value *LHS, Value *RHS,
- Instruction *I) {
+Instruction *NaryReassociate::tryReassociateBinaryOp(Value *LHS, Value *RHS,
+ BinaryOperator *I) {
Value *A = nullptr, *B = nullptr;
- // To be conservative, we reassociate I only when it is the only user of A+B.
- if (LHS->hasOneUse() && match(LHS, m_Add(m_Value(A), m_Value(B)))) {
- // I = (A + B) + RHS
- // = (A + RHS) + B or (B + RHS) + A
+ // To be conservative, we reassociate I only when it is the only user of (A op
+ // B).
+ if (LHS->hasOneUse() && matchTernaryOp(I, LHS, A, B)) {
+ // I = (A op B) op RHS
+ // = (A op RHS) op B or (B op RHS) op A
const SCEV *AExpr = SE->getSCEV(A), *BExpr = SE->getSCEV(B);
const SCEV *RHSExpr = SE->getSCEV(RHS);
- if (auto *NewI = tryReassociatedAdd(SE->getAddExpr(AExpr, RHSExpr), B, I))
- return NewI;
- if (auto *NewI = tryReassociatedAdd(SE->getAddExpr(BExpr, RHSExpr), A, I))
- return NewI;
+ if (BExpr != RHSExpr) {
+ if (auto *NewI =
+ tryReassociatedBinaryOp(getBinarySCEV(I, AExpr, RHSExpr), B, I))
+ return NewI;
+ }
+ if (AExpr != RHSExpr) {
+ if (auto *NewI =
+ tryReassociatedBinaryOp(getBinarySCEV(I, BExpr, RHSExpr), A, I))
+ return NewI;
+ }
}
return nullptr;
}
-Instruction *NaryReassociate::tryReassociatedAdd(const SCEV *LHSExpr,
- Value *RHS, Instruction *I) {
- auto Pos = SeenExprs.find(LHSExpr);
- // Bail out if LHSExpr is not previously seen.
+Instruction *NaryReassociate::tryReassociatedBinaryOp(const SCEV *LHSExpr,
+ Value *RHS,
+ BinaryOperator *I) {
+ // Look for the closest dominator LHS of I that computes LHSExpr, and replace
+ // I with LHS op RHS.
+ auto *LHS = findClosestMatchingDominator(LHSExpr, I);
+ if (LHS == nullptr)
+ return nullptr;
+
+ Instruction *NewI = nullptr;
+ switch (I->getOpcode()) {
+ case Instruction::Add:
+ NewI = BinaryOperator::CreateAdd(LHS, RHS, "", I);
+ break;
+ case Instruction::Mul:
+ NewI = BinaryOperator::CreateMul(LHS, RHS, "", I);
+ break;
+ default:
+ llvm_unreachable("Unexpected instruction.");
+ }
+ NewI->takeName(I);
+ return NewI;
+}
+
+bool NaryReassociate::matchTernaryOp(BinaryOperator *I, Value *V, Value *&Op1,
+ Value *&Op2) {
+ switch (I->getOpcode()) {
+ case Instruction::Add:
+ return match(V, m_Add(m_Value(Op1), m_Value(Op2)));
+ case Instruction::Mul:
+ return match(V, m_Mul(m_Value(Op1), m_Value(Op2)));
+ default:
+ llvm_unreachable("Unexpected instruction.");
+ }
+ return false;
+}
+
+const SCEV *NaryReassociate::getBinarySCEV(BinaryOperator *I, const SCEV *LHS,
+ const SCEV *RHS) {
+ switch (I->getOpcode()) {
+ case Instruction::Add:
+ return SE->getAddExpr(LHS, RHS);
+ case Instruction::Mul:
+ return SE->getMulExpr(LHS, RHS);
+ default:
+ llvm_unreachable("Unexpected instruction.");
+ }
+ return nullptr;
+}
+
+Instruction *
+NaryReassociate::findClosestMatchingDominator(const SCEV *CandidateExpr,
+ Instruction *Dominatee) {
+ auto Pos = SeenExprs.find(CandidateExpr);
if (Pos == SeenExprs.end())
return nullptr;
- auto &LHSCandidates = Pos->second;
- // Look for the closest dominator LHS of I that computes LHSExpr, and replace
- // I with LHS + RHS.
- //
- // Because we traverse the dominator tree in the pre-order, a
+ auto &Candidates = Pos->second;
+ // Because we process the basic blocks in pre-order of the dominator tree, a
// candidate that doesn't dominate the current instruction won't dominate any
// future instruction either. Therefore, we pop it out of the stack. This
// optimization makes the algorithm O(n).
- while (!LHSCandidates.empty()) {
- Instruction *LHS = LHSCandidates.back();
- if (DT->dominates(LHS, I)) {
- Instruction *NewI = BinaryOperator::CreateAdd(LHS, RHS, "", I);
- NewI->takeName(I);
- return NewI;
+ while (!Candidates.empty()) {
+ // Candidates stores WeakVHs, so a candidate can be nullptr if it's removed
+ // during rewriting.
+ if (Value *Candidate = Candidates.back()) {
+ Instruction *CandidateInstruction = cast<Instruction>(Candidate);
+ if (DT->dominates(CandidateInstruction, Dominatee))
+ return CandidateInstruction;
}
- LHSCandidates.pop_back();
+ Candidates.pop_back();
}
return nullptr;
}