1 //===- NaryReassociate.cpp - Reassociate n-ary expressions ----------------===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This pass reassociates n-ary add expressions and eliminates the redundancy
10 // exposed by the reassociation.
12 // A motivating example:
14 // void foo(int a, int b) {
19 // An ideal compiler should reassociate (a + 2) + b to (a + b) + 2 and simplify
26 // However, the Reassociate pass is unable to do that because it processes each
27 // instruction individually and believes (a + 2) + b is the best form according
28 // to its rank system.
30 // To address this limitation, NaryReassociate reassociates an expression in a
31 // form that reuses existing instructions. As a result, NaryReassociate can
32 // reassociate (a + 2) + b in the example to (a + b) + 2 because it detects that
33 // (a + b) is computed before.
35 // NaryReassociate works as follows. For every instruction in the form of (a +
36 // b) + c, it checks whether a + c or b + c is already computed by a dominating
37 // instruction. If so, it then reassociates (a + b) + c into (a + c) + b or (b +
38 // c) + a and removes the redundancy accordingly. To efficiently look up whether
39 // an expression is computed before, we store each instruction seen and its SCEV
40 // into an SCEV-to-instruction map.
42 // Although the algorithm pattern-matches only ternary additions, it
43 // automatically handles many >3-ary expressions by walking through the function
44 // in the depth-first order. For example, given
49 // NaryReassociate first rewrites (a + b) + c to (a + c) + b, and then rewrites
50 // ((a + c) + b) + d into ((a + c) + d) + b.
52 // Finally, the above dominator-based algorithm may need to be run multiple
53 // iterations before emitting optimal code. One source of this need is that we
54 // only split an operand when it is used only once. The above algorithm can
55 // eliminate an instruction and decrease the usage count of its operands. As a
56 // result, an instruction that previously had multiple uses may become a
57 // single-use instruction and thus eligible for split consideration. For
66 // In the first iteration, we cannot reassociate abc to ac+b because ab is used
67 // twice. However, we can reassociate ab2c to abc+b in the first iteration. As a
68 // result, ab2 becomes dead and ab will be used only once in the second
71 // Limitations and TODO items:
73 // 1) We only considers n-ary adds and muls for now. This should be extended
76 //===----------------------------------------------------------------------===//
78 #include "llvm/Transforms/Scalar/NaryReassociate.h"
79 #include "llvm/ADT/DepthFirstIterator.h"
80 #include "llvm/ADT/SmallVector.h"
81 #include "llvm/Analysis/AssumptionCache.h"
82 #include "llvm/Analysis/ScalarEvolution.h"
83 #include "llvm/Analysis/ScalarEvolutionExpressions.h"
84 #include "llvm/Analysis/TargetLibraryInfo.h"
85 #include "llvm/Analysis/TargetTransformInfo.h"
86 #include "llvm/Analysis/ValueTracking.h"
87 #include "llvm/IR/BasicBlock.h"
88 #include "llvm/IR/Constants.h"
89 #include "llvm/IR/DataLayout.h"
90 #include "llvm/IR/DerivedTypes.h"
91 #include "llvm/IR/Dominators.h"
92 #include "llvm/IR/Function.h"
93 #include "llvm/IR/GetElementPtrTypeIterator.h"
94 #include "llvm/IR/IRBuilder.h"
95 #include "llvm/IR/InstrTypes.h"
96 #include "llvm/IR/Instruction.h"
97 #include "llvm/IR/Instructions.h"
98 #include "llvm/IR/Module.h"
99 #include "llvm/IR/Operator.h"
100 #include "llvm/IR/PatternMatch.h"
101 #include "llvm/IR/Type.h"
102 #include "llvm/IR/Value.h"
103 #include "llvm/IR/ValueHandle.h"
104 #include "llvm/InitializePasses.h"
105 #include "llvm/Pass.h"
106 #include "llvm/Support/Casting.h"
107 #include "llvm/Support/ErrorHandling.h"
108 #include "llvm/Transforms/Scalar.h"
109 #include "llvm/Transforms/Utils/Local.h"
110 #include "llvm/Transforms/Utils/ScalarEvolutionExpander.h"
114 using namespace llvm;
115 using namespace PatternMatch;
117 #define DEBUG_TYPE "nary-reassociate"
121 class NaryReassociateLegacyPass : public FunctionPass {
125 NaryReassociateLegacyPass() : FunctionPass(ID) {
126 initializeNaryReassociateLegacyPassPass(*PassRegistry::getPassRegistry());
129 bool doInitialization(Module &M) override {
133 bool runOnFunction(Function &F) override;
135 void getAnalysisUsage(AnalysisUsage &AU) const override {
136 AU.addPreserved<DominatorTreeWrapperPass>();
137 AU.addPreserved<ScalarEvolutionWrapperPass>();
138 AU.addPreserved<TargetLibraryInfoWrapperPass>();
139 AU.addRequired<AssumptionCacheTracker>();
140 AU.addRequired<DominatorTreeWrapperPass>();
141 AU.addRequired<ScalarEvolutionWrapperPass>();
142 AU.addRequired<TargetLibraryInfoWrapperPass>();
143 AU.addRequired<TargetTransformInfoWrapperPass>();
144 AU.setPreservesCFG();
148 NaryReassociatePass Impl;
151 } // end anonymous namespace
153 char NaryReassociateLegacyPass::ID = 0;
155 INITIALIZE_PASS_BEGIN(NaryReassociateLegacyPass, "nary-reassociate",
156 "Nary reassociation", false, false)
157 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
158 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
159 INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
160 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
161 INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
162 INITIALIZE_PASS_END(NaryReassociateLegacyPass, "nary-reassociate",
163 "Nary reassociation", false, false)
165 FunctionPass *llvm::createNaryReassociatePass() {
166 return new NaryReassociateLegacyPass();
169 bool NaryReassociateLegacyPass::runOnFunction(Function &F) {
173 auto *AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
174 auto *DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
175 auto *SE = &getAnalysis<ScalarEvolutionWrapperPass>().getSE();
176 auto *TLI = &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
177 auto *TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
179 return Impl.runImpl(F, AC, DT, SE, TLI, TTI);
182 PreservedAnalyses NaryReassociatePass::run(Function &F,
183 FunctionAnalysisManager &AM) {
184 auto *AC = &AM.getResult<AssumptionAnalysis>(F);
185 auto *DT = &AM.getResult<DominatorTreeAnalysis>(F);
186 auto *SE = &AM.getResult<ScalarEvolutionAnalysis>(F);
187 auto *TLI = &AM.getResult<TargetLibraryAnalysis>(F);
188 auto *TTI = &AM.getResult<TargetIRAnalysis>(F);
190 if (!runImpl(F, AC, DT, SE, TLI, TTI))
191 return PreservedAnalyses::all();
193 PreservedAnalyses PA;
194 PA.preserveSet<CFGAnalyses>();
195 PA.preserve<ScalarEvolutionAnalysis>();
199 bool NaryReassociatePass::runImpl(Function &F, AssumptionCache *AC_,
200 DominatorTree *DT_, ScalarEvolution *SE_,
201 TargetLibraryInfo *TLI_,
202 TargetTransformInfo *TTI_) {
208 DL = &F.getParent()->getDataLayout();
210 bool Changed = false, ChangedInThisIteration;
212 ChangedInThisIteration = doOneIteration(F);
213 Changed |= ChangedInThisIteration;
214 } while (ChangedInThisIteration);
218 bool NaryReassociatePass::doOneIteration(Function &F) {
219 bool Changed = false;
221 // Process the basic blocks in a depth first traversal of the dominator
222 // tree. This order ensures that all bases of a candidate are in Candidates
223 // when we process it.
224 SmallVector<WeakTrackingVH, 16> DeadInsts;
225 for (const auto Node : depth_first(DT)) {
226 BasicBlock *BB = Node->getBlock();
227 for (Instruction &OrigI : *BB) {
228 const SCEV *OrigSCEV = nullptr;
229 if (Instruction *NewI = tryReassociate(&OrigI, OrigSCEV)) {
231 OrigI.replaceAllUsesWith(NewI);
233 // Add 'OrigI' to the list of dead instructions.
234 DeadInsts.push_back(WeakTrackingVH(&OrigI));
235 // Add the rewritten instruction to SeenExprs; the original
236 // instruction is deleted.
237 const SCEV *NewSCEV = SE->getSCEV(NewI);
238 SeenExprs[NewSCEV].push_back(WeakTrackingVH(NewI));
240 // Ideally, NewSCEV should equal OldSCEV because tryReassociate(I)
241 // is equivalent to I. However, ScalarEvolution::getSCEV may
242 // weaken nsw causing NewSCEV not to equal OldSCEV. For example,
243 // suppose we reassociate
244 // I = &a[sext(i +nsw j)] // assuming sizeof(a[0]) = 4
246 // NewI = &a[sext(i)] + sext(j).
248 // ScalarEvolution computes
249 // getSCEV(I) = a + 4 * sext(i + j)
250 // getSCEV(newI) = a + 4 * sext(i) + 4 * sext(j)
251 // which are different SCEVs.
253 // To alleviate this issue of ScalarEvolution not always capturing
254 // equivalence, we add I to SeenExprs[OldSCEV] as well so that we can
255 // map both SCEV before and after tryReassociate(I) to I.
257 // This improvement is exercised in @reassociate_gep_nsw in
259 if (NewSCEV != OrigSCEV)
260 SeenExprs[OrigSCEV].push_back(WeakTrackingVH(NewI));
262 SeenExprs[OrigSCEV].push_back(WeakTrackingVH(&OrigI));
265 // Delete all dead instructions from 'DeadInsts'.
266 // Please note ScalarEvolution is updated along the way.
267 RecursivelyDeleteTriviallyDeadInstructionsPermissive(
268 DeadInsts, TLI, nullptr, [this](Value *V) { SE->forgetValue(V); });
273 template <typename PredT>
275 NaryReassociatePass::matchAndReassociateMinOrMax(Instruction *I,
276 const SCEV *&OrigSCEV) {
277 Value *LHS = nullptr;
278 Value *RHS = nullptr;
281 MaxMin_match<ICmpInst, bind_ty<Value>, bind_ty<Value>, PredT>(
282 m_Value(LHS), m_Value(RHS));
283 if (match(I, MinMaxMatcher)) {
284 OrigSCEV = SE->getSCEV(I);
285 if (auto *NewMinMax = dyn_cast_or_null<Instruction>(
286 tryReassociateMinOrMax(I, MinMaxMatcher, LHS, RHS)))
288 if (auto *NewMinMax = dyn_cast_or_null<Instruction>(
289 tryReassociateMinOrMax(I, MinMaxMatcher, RHS, LHS)))
295 Instruction *NaryReassociatePass::tryReassociate(Instruction * I,
296 const SCEV *&OrigSCEV) {
298 if (!SE->isSCEVable(I->getType()))
301 switch (I->getOpcode()) {
302 case Instruction::Add:
303 case Instruction::Mul:
304 OrigSCEV = SE->getSCEV(I);
305 return tryReassociateBinaryOp(cast<BinaryOperator>(I));
306 case Instruction::GetElementPtr:
307 OrigSCEV = SE->getSCEV(I);
308 return tryReassociateGEP(cast<GetElementPtrInst>(I));
313 // Try to match signed/unsigned Min/Max.
314 Instruction *ResI = nullptr;
315 // TODO: Currently min/max reassociation is restricted to integer types only
316 // due to use of SCEVExpander which my introduce incompatible forms of min/max
317 // for pointer types.
318 if (I->getType()->isIntegerTy())
319 if ((ResI = matchAndReassociateMinOrMax<umin_pred_ty>(I, OrigSCEV)) ||
320 (ResI = matchAndReassociateMinOrMax<smin_pred_ty>(I, OrigSCEV)) ||
321 (ResI = matchAndReassociateMinOrMax<umax_pred_ty>(I, OrigSCEV)) ||
322 (ResI = matchAndReassociateMinOrMax<smax_pred_ty>(I, OrigSCEV)))
328 static bool isGEPFoldable(GetElementPtrInst *GEP,
329 const TargetTransformInfo *TTI) {
330 SmallVector<const Value *, 4> Indices(GEP->indices());
331 return TTI->getGEPCost(GEP->getSourceElementType(), GEP->getPointerOperand(),
332 Indices) == TargetTransformInfo::TCC_Free;
335 Instruction *NaryReassociatePass::tryReassociateGEP(GetElementPtrInst *GEP) {
336 // Not worth reassociating GEP if it is foldable.
337 if (isGEPFoldable(GEP, TTI))
340 gep_type_iterator GTI = gep_type_begin(*GEP);
341 for (unsigned I = 1, E = GEP->getNumOperands(); I != E; ++I, ++GTI) {
342 if (GTI.isSequential()) {
343 if (auto *NewGEP = tryReassociateGEPAtIndex(GEP, I - 1,
344 GTI.getIndexedType())) {
352 bool NaryReassociatePass::requiresSignExtension(Value *Index,
353 GetElementPtrInst *GEP) {
354 unsigned IndexSizeInBits =
355 DL->getIndexSizeInBits(GEP->getType()->getPointerAddressSpace());
356 return cast<IntegerType>(Index->getType())->getBitWidth() < IndexSizeInBits;
360 NaryReassociatePass::tryReassociateGEPAtIndex(GetElementPtrInst *GEP,
361 unsigned I, Type *IndexedType) {
362 Value *IndexToSplit = GEP->getOperand(I + 1);
363 if (SExtInst *SExt = dyn_cast<SExtInst>(IndexToSplit)) {
364 IndexToSplit = SExt->getOperand(0);
365 } else if (ZExtInst *ZExt = dyn_cast<ZExtInst>(IndexToSplit)) {
366 // zext can be treated as sext if the source is non-negative.
367 if (isKnownNonNegative(ZExt->getOperand(0), *DL, 0, AC, GEP, DT))
368 IndexToSplit = ZExt->getOperand(0);
371 if (AddOperator *AO = dyn_cast<AddOperator>(IndexToSplit)) {
372 // If the I-th index needs sext and the underlying add is not equipped with
373 // nsw, we cannot split the add because
374 // sext(LHS + RHS) != sext(LHS) + sext(RHS).
375 if (requiresSignExtension(IndexToSplit, GEP) &&
376 computeOverflowForSignedAdd(AO, *DL, AC, GEP, DT) !=
377 OverflowResult::NeverOverflows)
380 Value *LHS = AO->getOperand(0), *RHS = AO->getOperand(1);
381 // IndexToSplit = LHS + RHS.
382 if (auto *NewGEP = tryReassociateGEPAtIndex(GEP, I, LHS, RHS, IndexedType))
384 // Symmetrically, try IndexToSplit = RHS + LHS.
387 tryReassociateGEPAtIndex(GEP, I, RHS, LHS, IndexedType))
395 NaryReassociatePass::tryReassociateGEPAtIndex(GetElementPtrInst *GEP,
396 unsigned I, Value *LHS,
397 Value *RHS, Type *IndexedType) {
398 // Look for GEP's closest dominator that has the same SCEV as GEP except that
399 // the I-th index is replaced with LHS.
400 SmallVector<const SCEV *, 4> IndexExprs;
401 for (Use &Index : GEP->indices())
402 IndexExprs.push_back(SE->getSCEV(Index));
403 // Replace the I-th index with LHS.
404 IndexExprs[I] = SE->getSCEV(LHS);
405 if (isKnownNonNegative(LHS, *DL, 0, AC, GEP, DT) &&
406 DL->getTypeSizeInBits(LHS->getType()).getFixedValue() <
407 DL->getTypeSizeInBits(GEP->getOperand(I)->getType())
409 // Zero-extend LHS if it is non-negative. InstCombine canonicalizes sext to
410 // zext if the source operand is proved non-negative. We should do that
411 // consistently so that CandidateExpr more likely appears before. See
412 // @reassociate_gep_assume for an example of this canonicalization.
414 SE->getZeroExtendExpr(IndexExprs[I], GEP->getOperand(I)->getType());
416 const SCEV *CandidateExpr = SE->getGEPExpr(cast<GEPOperator>(GEP),
419 Value *Candidate = findClosestMatchingDominator(CandidateExpr, GEP);
420 if (Candidate == nullptr)
423 IRBuilder<> Builder(GEP);
424 // Candidate does not necessarily have the same pointer type as GEP. Use
425 // bitcast or pointer cast to make sure they have the same type, so that the
426 // later RAUW doesn't complain.
427 Candidate = Builder.CreateBitOrPointerCast(Candidate, GEP->getType());
428 assert(Candidate->getType() == GEP->getType());
430 // NewGEP = (char *)Candidate + RHS * sizeof(IndexedType)
431 uint64_t IndexedSize = DL->getTypeAllocSize(IndexedType);
432 Type *ElementType = GEP->getResultElementType();
433 uint64_t ElementSize = DL->getTypeAllocSize(ElementType);
434 // Another less rare case: because I is not necessarily the last index of the
435 // GEP, the size of the type at the I-th index (IndexedSize) is not
436 // necessarily divisible by ElementSize. For example,
445 // sizeof(S) = 100 is indivisible by sizeof(int64) = 8.
447 // TODO: bail out on this case for now. We could emit uglygep.
448 if (IndexedSize % ElementSize != 0)
451 // NewGEP = &Candidate[RHS * (sizeof(IndexedType) / sizeof(Candidate[0])));
452 Type *PtrIdxTy = DL->getIndexType(GEP->getType());
453 if (RHS->getType() != PtrIdxTy)
454 RHS = Builder.CreateSExtOrTrunc(RHS, PtrIdxTy);
455 if (IndexedSize != ElementSize) {
456 RHS = Builder.CreateMul(
457 RHS, ConstantInt::get(PtrIdxTy, IndexedSize / ElementSize));
459 GetElementPtrInst *NewGEP = cast<GetElementPtrInst>(
460 Builder.CreateGEP(GEP->getResultElementType(), Candidate, RHS));
461 NewGEP->setIsInBounds(GEP->isInBounds());
462 NewGEP->takeName(GEP);
466 Instruction *NaryReassociatePass::tryReassociateBinaryOp(BinaryOperator *I) {
467 Value *LHS = I->getOperand(0), *RHS = I->getOperand(1);
468 // There is no need to reassociate 0.
469 if (SE->getSCEV(I)->isZero())
471 if (auto *NewI = tryReassociateBinaryOp(LHS, RHS, I))
473 if (auto *NewI = tryReassociateBinaryOp(RHS, LHS, I))
478 Instruction *NaryReassociatePass::tryReassociateBinaryOp(Value *LHS, Value *RHS,
480 Value *A = nullptr, *B = nullptr;
481 // To be conservative, we reassociate I only when it is the only user of (A op
483 if (LHS->hasOneUse() && matchTernaryOp(I, LHS, A, B)) {
484 // I = (A op B) op RHS
485 // = (A op RHS) op B or (B op RHS) op A
486 const SCEV *AExpr = SE->getSCEV(A), *BExpr = SE->getSCEV(B);
487 const SCEV *RHSExpr = SE->getSCEV(RHS);
488 if (BExpr != RHSExpr) {
490 tryReassociatedBinaryOp(getBinarySCEV(I, AExpr, RHSExpr), B, I))
493 if (AExpr != RHSExpr) {
495 tryReassociatedBinaryOp(getBinarySCEV(I, BExpr, RHSExpr), A, I))
502 Instruction *NaryReassociatePass::tryReassociatedBinaryOp(const SCEV *LHSExpr,
505 // Look for the closest dominator LHS of I that computes LHSExpr, and replace
506 // I with LHS op RHS.
507 auto *LHS = findClosestMatchingDominator(LHSExpr, I);
511 Instruction *NewI = nullptr;
512 switch (I->getOpcode()) {
513 case Instruction::Add:
514 NewI = BinaryOperator::CreateAdd(LHS, RHS, "", I);
516 case Instruction::Mul:
517 NewI = BinaryOperator::CreateMul(LHS, RHS, "", I);
520 llvm_unreachable("Unexpected instruction.");
526 bool NaryReassociatePass::matchTernaryOp(BinaryOperator *I, Value *V,
527 Value *&Op1, Value *&Op2) {
528 switch (I->getOpcode()) {
529 case Instruction::Add:
530 return match(V, m_Add(m_Value(Op1), m_Value(Op2)));
531 case Instruction::Mul:
532 return match(V, m_Mul(m_Value(Op1), m_Value(Op2)));
534 llvm_unreachable("Unexpected instruction.");
539 const SCEV *NaryReassociatePass::getBinarySCEV(BinaryOperator *I,
542 switch (I->getOpcode()) {
543 case Instruction::Add:
544 return SE->getAddExpr(LHS, RHS);
545 case Instruction::Mul:
546 return SE->getMulExpr(LHS, RHS);
548 llvm_unreachable("Unexpected instruction.");
554 NaryReassociatePass::findClosestMatchingDominator(const SCEV *CandidateExpr,
555 Instruction *Dominatee) {
556 auto Pos = SeenExprs.find(CandidateExpr);
557 if (Pos == SeenExprs.end())
560 auto &Candidates = Pos->second;
561 // Because we process the basic blocks in pre-order of the dominator tree, a
562 // candidate that doesn't dominate the current instruction won't dominate any
563 // future instruction either. Therefore, we pop it out of the stack. This
564 // optimization makes the algorithm O(n).
565 while (!Candidates.empty()) {
566 // Candidates stores WeakTrackingVHs, so a candidate can be nullptr if it's
569 if (Value *Candidate = Candidates.back()) {
570 Instruction *CandidateInstruction = cast<Instruction>(Candidate);
571 if (DT->dominates(CandidateInstruction, Dominatee))
572 return CandidateInstruction;
574 Candidates.pop_back();
579 template <typename MaxMinT> static SCEVTypes convertToSCEVype(MaxMinT &MM) {
580 if (std::is_same_v<smax_pred_ty, typename MaxMinT::PredType>)
582 else if (std::is_same_v<umax_pred_ty, typename MaxMinT::PredType>)
584 else if (std::is_same_v<smin_pred_ty, typename MaxMinT::PredType>)
586 else if (std::is_same_v<umin_pred_ty, typename MaxMinT::PredType>)
589 llvm_unreachable("Can't convert MinMax pattern to SCEV type");
594 // I - instruction matched by MaxMinMatch matcher
595 // MaxMinMatch - min/max idiom matcher
596 // LHS - first operand of I
597 // RHS - second operand of I
598 template <typename MaxMinT>
599 Value *NaryReassociatePass::tryReassociateMinOrMax(Instruction *I,
601 Value *LHS, Value *RHS) {
602 Value *A = nullptr, *B = nullptr;
603 MaxMinT m_MaxMin(m_Value(A), m_Value(B));
605 if (LHS->hasNUsesOrMore(3) ||
606 // The optimization is profitable only if LHS can be removed in the end.
607 // In other words LHS should be used (directly or indirectly) by I only.
608 llvm::any_of(LHS->users(),
611 !(U->hasOneUser() && *U->users().begin() == I);
613 !match(LHS, m_MaxMin))
616 auto tryCombination = [&](Value *A, const SCEV *AExpr, Value *B,
617 const SCEV *BExpr, Value *C,
618 const SCEV *CExpr) -> Value * {
619 SmallVector<const SCEV *, 2> Ops1{BExpr, AExpr};
620 const SCEVTypes SCEVType = convertToSCEVype(m_MaxMin);
621 const SCEV *R1Expr = SE->getMinMaxExpr(SCEVType, Ops1);
623 Instruction *R1MinMax = findClosestMatchingDominator(R1Expr, I);
628 LLVM_DEBUG(dbgs() << "NARY: Found common sub-expr: " << *R1MinMax << "\n");
630 SmallVector<const SCEV *, 2> Ops2{SE->getUnknown(C),
631 SE->getUnknown(R1MinMax)};
632 const SCEV *R2Expr = SE->getMinMaxExpr(SCEVType, Ops2);
634 SCEVExpander Expander(*SE, *DL, "nary-reassociate");
635 Value *NewMinMax = Expander.expandCodeFor(R2Expr, I->getType(), I);
636 NewMinMax->setName(Twine(I->getName()).concat(".nary"));
638 LLVM_DEBUG(dbgs() << "NARY: Deleting: " << *I << "\n"
639 << "NARY: Inserting: " << *NewMinMax << "\n");
643 const SCEV *AExpr = SE->getSCEV(A);
644 const SCEV *BExpr = SE->getSCEV(B);
645 const SCEV *RHSExpr = SE->getSCEV(RHS);
647 if (BExpr != RHSExpr) {
648 // Try (A op RHS) op B
649 if (auto *NewMinMax = tryCombination(A, AExpr, RHS, RHSExpr, B, BExpr))
653 if (AExpr != RHSExpr) {
654 // Try (RHS op B) op A
655 if (auto *NewMinMax = tryCombination(RHS, RHSExpr, B, BExpr, A, AExpr))