Transforms/Utils/SimplifyIndVar.cpp

78     Value *foldIVUser(Instruction *UseInst, Instruction *IVOperand);
80     bool eliminateIdentitySCEV(Instruction *UseInst, Instruction *IVOperand);
81     bool replaceIVUserWithLoopInvariant(Instruction *UseInst);
86     bool eliminateIVUser(Instruction *UseInst, Instruction *IVOperand);
103 /// IVOperand is guaranteed SCEVable, but UseInst may not be.
108 Value *SimplifyIndvar::foldIVUser(Instruction *UseInst, Instruction *IVOperand) {
113   switch (UseInst->getOpcode()) {
120     if (IVOperand != UseInst->getOperand(OperIdx) ||
121         !isa<ConstantInt>(UseInst->getOperand(1)))
134     ConstantInt *D = cast<ConstantInt>(UseInst->getOperand(1));
135     if (UseInst->getOpcode() == Instruction::LShr) {
137       uint32_t BitWidth = cast<IntegerType>(UseInst->getType())->getBitWidth();
141       D = ConstantInt::get(UseInst->getContext(),
147     if (UseInst->isExact() &&
152   if (!SE->isSCEVable(UseInst->getType()))
156   if (SE->getSCEV(UseInst) != FoldedExpr)
160                     << " -> " << *UseInst << '\n');
162   UseInst->setOperand(OperIdx, IVSrc);
163   assert(SE->getSCEV(UseInst) == FoldedExpr && "bad SCEV with folded oper");
166     UseInst->dropPoisonGeneratingFlags();
615 /// but UseInst may not be.
616 bool SimplifyIndvar::eliminateIVUser(Instruction *UseInst,
618   if (ICmpInst *ICmp = dyn_cast<ICmpInst>(UseInst)) {
622   if (BinaryOperator *Bin = dyn_cast<BinaryOperator>(UseInst)) {
633   if (auto *WO = dyn_cast<WithOverflowInst>(UseInst))
637   if (auto *SI = dyn_cast<SaturatingInst>(UseInst))
641   if (auto *TI = dyn_cast<TruncInst>(UseInst))
645   if (eliminateIdentitySCEV(UseInst, IVOperand))
658 /// Replace the UseInst with a constant if possible.
686 bool SimplifyIndvar::eliminateIdentitySCEV(Instruction *UseInst,
688   if (!SE->isSCEVable(UseInst->getType()) ||
689       (UseInst->getType() != IVOperand->getType()) ||
690       (SE->getSCEV(UseInst) != SE->getSCEV(IVOperand)))
709   if (isa<PHINode>(UseInst))
710     // If UseInst is not a PHI node then we know that IVOperand dominates
711     // UseInst directly from the legality of SSA.
712     if (!DT || !DT->dominates(IVOperand, UseInst))
715   if (!LI->replacementPreservesLCSSAForm(UseInst, IVOperand))
718   LLVM_DEBUG(dbgs() << "INDVARS: Eliminated identity: " << *UseInst << '\n');
720   UseInst->replaceAllUsesWith(IVOperand);
723   DeadInsts.emplace_back(UseInst);
870     Instruction *UseInst = UseOper.first;
876     if (isInstructionTriviallyDead(UseInst, /* TLI */ nullptr)) {
877       DeadInsts.emplace_back(UseInst);
882     if (UseInst == CurrIV) continue;
884     // Try to replace UseInst with a loop invariant before any other
886     if (replaceIVUserWithLoopInvariant(UseInst))
893       Value *NewOper = foldIVUser(UseInst, IVOperand);
901     if (eliminateIVUser(UseInst, IVOperand)) {
906     if (BinaryOperator *BO = dyn_cast<BinaryOperator>(UseInst)) {
916     CastInst *Cast = dyn_cast<CastInst>(UseInst);
921     if (isSimpleIVUser(UseInst, L, SE)) {
922       pushIVUsers(UseInst, L, Simplified, SimpleIVUsers);