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teach a couple of instcombine transformations involving PHIs to
not turn a PHI in a legal type into a PHI of an illegal type, and add a new optimization that breaks up insane integer PHI nodes into small pieces (PR3451). llvm-svn: 86443
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@ -283,6 +283,8 @@ namespace {
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Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
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Instruction *visitCallInst(CallInst &CI);
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Instruction *visitInvokeInst(InvokeInst &II);
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Instruction *SliceUpIllegalIntegerPHI(PHINode &PN);
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Instruction *visitPHINode(PHINode &PN);
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Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
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Instruction *visitAllocaInst(AllocaInst &AI);
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@ -8083,8 +8085,7 @@ bool InstCombiner::CanEvaluateInDifferentType(Value *V, const Type *Ty,
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Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
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bool isSigned) {
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if (Constant *C = dyn_cast<Constant>(V))
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return ConstantExpr::getIntegerCast(C, Ty,
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isSigned /*Sext or ZExt*/);
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return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
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// Otherwise, it must be an instruction.
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Instruction *I = cast<Instruction>(V);
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@ -8117,8 +8118,7 @@ Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
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return I->getOperand(0);
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// Otherwise, must be the same type of cast, so just reinsert a new one.
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Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),
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Ty);
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Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),Ty);
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break;
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case Instruction::Select: {
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Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
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@ -8167,10 +8167,18 @@ Instruction *InstCombiner::commonCastTransforms(CastInst &CI) {
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return NV;
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// If we are casting a PHI then fold the cast into the PHI
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if (isa<PHINode>(Src))
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if (isa<PHINode>(Src)) {
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// We don't do this if this would create a PHI node with an illegal type if
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// it is currently legal.
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if (!isa<IntegerType>(Src->getType()) ||
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!isa<IntegerType>(CI.getType()) ||
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(TD && TD->isLegalInteger(CI.getType()->getPrimitiveSizeInBits())) ||
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(TD && !TD->isLegalInteger(Src->getType()->getPrimitiveSizeInBits())))
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if (Instruction *NV = FoldOpIntoPhi(CI))
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return NV;
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}
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return 0;
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}
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@ -10886,6 +10894,15 @@ Instruction *InstCombiner::FoldPHIArgOpIntoPHI(PHINode &PN) {
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if (isa<CastInst>(FirstInst)) {
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CastSrcTy = FirstInst->getOperand(0)->getType();
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// If this is a legal integer PHI node, and pulling the operation through
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// would cause it to be an illegal integer PHI, don't do the transformation.
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if (!TD ||
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(isa<IntegerType>(PN.getType()) &&
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isa<IntegerType>(CastSrcTy) &&
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TD->isLegalInteger(PN.getType()->getPrimitiveSizeInBits()) &&
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!TD->isLegalInteger(CastSrcTy->getPrimitiveSizeInBits())))
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return 0;
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} else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
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// Can fold binop, compare or shift here if the RHS is a constant,
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// otherwise call FoldPHIArgBinOpIntoPHI.
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@ -10998,6 +11015,123 @@ static bool PHIsEqualValue(PHINode *PN, Value *NonPhiInVal,
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}
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namespace {
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struct PHIUsageRecord {
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unsigned Shift; // The amount shifted.
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Instruction *Inst; // The trunc instruction.
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PHIUsageRecord(unsigned Sh, Instruction *User) : Shift(Sh), Inst(User) {}
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bool operator<(const PHIUsageRecord &RHS) const {
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if (Shift < RHS.Shift) return true;
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return Shift == RHS.Shift &&
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Inst->getType()->getPrimitiveSizeInBits() <
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RHS.Inst->getType()->getPrimitiveSizeInBits();
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}
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};
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}
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/// SliceUpIllegalIntegerPHI - This is an integer PHI and we know that it has an
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/// illegal type: see if it is only used by trunc or trunc(lshr) operations. If
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/// so, we split the PHI into the various pieces being extracted. This sort of
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/// thing is introduced when SROA promotes an aggregate to large integer values.
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///
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/// TODO: The user of the trunc may be an bitcast to float/double/vector or an
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/// inttoptr. We should produce new PHIs in the right type.
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///
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Instruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &PN) {
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SmallVector<PHIUsageRecord, 16> PHIUsers;
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for (Value::use_iterator UI = PN.use_begin(), E = PN.use_end();
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UI != E; ++UI) {
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Instruction *User = cast<Instruction>(*UI);
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// The PHI can use itself.
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if (User == &PN)
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continue;
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// Truncates are always ok.
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if (isa<TruncInst>(User)) {
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PHIUsers.push_back(PHIUsageRecord(0, User));
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continue;
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}
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// Otherwise it must be a lshr which can only be used by one trunc.
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if (User->getOpcode() != Instruction::LShr ||
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!User->hasOneUse() || !isa<TruncInst>(User->use_back()) ||
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!isa<ConstantInt>(User->getOperand(1)))
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return 0;
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unsigned Shift = cast<ConstantInt>(User->getOperand(1))->getZExtValue();
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PHIUsers.push_back(PHIUsageRecord(Shift, User->use_back()));
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}
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// If we have no users, they must be all self uses, just nuke the PHI.
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if (PHIUsers.empty())
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return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
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// If this phi node is transformable, create new PHIs for all the pieces
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// extracted out of it. First, sort the users by their offset and size.
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array_pod_sort(PHIUsers.begin(), PHIUsers.end());
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DenseMap<BasicBlock*, Value*> PredValues;
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unsigned UserI = 0, UserE = PHIUsers.size();
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while (1) {
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assert(UserI != UserE && "Iteration fail, loop below should catch this");
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unsigned Offset = PHIUsers[UserI].Shift;
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const Type *Ty = PHIUsers[UserI].Inst->getType();
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// Create the new PHI node for this user.
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PHINode *EltPHI =
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PHINode::Create(Ty, PN.getName()+".off"+Twine(Offset), &PN);
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for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
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BasicBlock *Pred = PN.getIncomingBlock(i);
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Value *&PredVal = PredValues[Pred];
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// If we already have a value for this predecessor, reuse it.
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if (PredVal) {
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EltPHI->addIncoming(PredVal, Pred);
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continue;
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}
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// Handle the PHI self-reuse case.
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Value *InVal = PN.getIncomingValue(i);
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if (InVal == &PN) {
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PredVal = EltPHI;
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EltPHI->addIncoming(PredVal, Pred);
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continue;
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}
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// Otherwise, do an extract in the predecessor.
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Builder->SetInsertPoint(Pred, Pred->getTerminator());
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if (Offset)
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InVal = Builder->CreateLShr(InVal, ConstantInt::get(InVal->getType(),
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Offset), "extract");
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InVal = Builder->CreateTrunc(InVal, Ty, "extract.t");
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PredVal = InVal;
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EltPHI->addIncoming(PredVal, Pred);
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}
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PredValues.clear();
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// Now that we have a new PHI node, replace all uses of this piece of the
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// PHI with the one new PHI.
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while (PHIUsers[UserI].Shift == Offset &&
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PHIUsers[UserI].Inst->getType() == Ty) {
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ReplaceInstUsesWith(*PHIUsers[UserI].Inst, EltPHI);
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// If we replaced the last PHI user, we're done. Just replace all the
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// remaining uses of the PHI (self uses and the lshrs with undefs.
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if (++UserI == UserE)
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return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
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}
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}
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}
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// PHINode simplification
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//
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Instruction *InstCombiner::visitPHINode(PHINode &PN) {
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@ -11103,6 +11237,15 @@ Instruction *InstCombiner::visitPHINode(PHINode &PN) {
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}
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}
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// If this is an integer PHI and we know that it has an illegal type, see if
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// it is only used by trunc or trunc(lshr) operations. If so, we split the
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// PHI into the various pieces being extracted. This sort of thing is
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// introduced when SROA promotes an aggregate to a single large integer type.
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if (isa<IntegerType>(PN.getType()) && TD &&
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!TD->isLegalInteger(PN.getType()->getPrimitiveSizeInBits()))
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if (Instruction *Res = SliceUpIllegalIntegerPHI(PN))
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return Res;
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return 0;
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}
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@ -2,6 +2,8 @@
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;
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; RUN: opt < %s -instcombine -S | FileCheck %s
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
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define i32 @test1(i32 %A, i1 %b) {
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BB0:
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br i1 %b, label %BB1, label %BB2
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@ -1,5 +1,7 @@
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; RUN: opt < %s -instcombine -S | not grep sext
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target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
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declare i32 @llvm.ctpop.i32(i32)
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declare i32 @llvm.ctlz.i32(i32)
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declare i32 @llvm.cttz.i32(i32)
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