[InstCombine] try to fold (select C, (sext A), B) into logical ops
Summary: Turn (select C, (sext A), B) into (sext (select C, A, B')) when A is i1 and B is a compatible constant, also for zext instead of sext. This will then be further folded into logical operations. The transformation would be valid for non-i1 types as well, but other parts of InstCombine prefer to have sext from non-i1 as an operand of select. Motivated by the shader compiler frontend in Mesa for AMDGPU, which emits i32 for boolean operations. With this change, the boolean logic is fully recovered. Reviewers: majnemer, spatel, tstellarAMD Subscribers: llvm-commits Differential Revision: https://reviews.llvm.org/D22747 llvm-svn: 277801
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@ -912,6 +912,37 @@ static Instruction *foldAddSubSelect(SelectInst &SI,
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return nullptr;
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return nullptr;
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}
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}
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/// If one of the operands is a sext/zext from i1 and the other is a constant,
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/// we may be able to create an i1 select which can be further folded to
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/// logical ops.
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static Instruction *foldSelectExtConst(InstCombiner::BuilderTy &Builder,
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SelectInst &SI, Instruction *EI,
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const APInt &C, bool isExtTrueVal,
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bool isSigned) {
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Value *SmallVal = EI->getOperand(0);
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Type *SmallType = SmallVal->getType();
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// TODO Handle larger types as well? Note this requires adjusting
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// FoldOpIntoSelect as well.
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if (!SmallType->getScalarType()->isIntegerTy(1))
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return nullptr;
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if (C != 0 && (isSigned || C != 1) &&
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(!isSigned || !C.isAllOnesValue()))
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return nullptr;
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Value *SmallConst = ConstantInt::get(SmallType, C.trunc(1));
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Value *TrueVal = isExtTrueVal ? SmallVal : SmallConst;
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Value *FalseVal = isExtTrueVal ? SmallConst : SmallVal;
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Value *Select = Builder.CreateSelect(SI.getOperand(0), TrueVal, FalseVal,
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"fold." + SI.getName());
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if (isSigned)
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return new SExtInst(Select, SI.getType());
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return new ZExtInst(Select, SI.getType());
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}
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Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
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Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
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Value *CondVal = SI.getCondition();
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Value *CondVal = SI.getCondition();
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Value *TrueVal = SI.getTrueValue();
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Value *TrueVal = SI.getTrueValue();
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@ -1098,6 +1129,31 @@ Instruction *InstCombiner::visitSelectInst(SelectInst &SI) {
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if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
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if (Instruction *IV = FoldSelectOpOp(SI, TI, FI))
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return IV;
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return IV;
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// (select C, (sext X), const) -> (sext (select C, X, const')) and
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// variations thereof when extending from i1, as that allows further folding
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// into logic ops. When the sext is from a larger type, we prefer to have it
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// as an operand.
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if (TI &&
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(TI->getOpcode() == Instruction::ZExt || TI->getOpcode() == Instruction::SExt)) {
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bool IsSExt = TI->getOpcode() == Instruction::SExt;
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const APInt *C;
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if (match(FalseVal, m_APInt(C))) {
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if (Instruction *IV =
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foldSelectExtConst(*Builder, SI, TI, *C, true, IsSExt))
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return IV;
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}
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}
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if (FI &&
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(FI->getOpcode() == Instruction::ZExt || FI->getOpcode() == Instruction::SExt)) {
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bool IsSExt = FI->getOpcode() == Instruction::SExt;
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const APInt *C;
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if (match(TrueVal, m_APInt(C))) {
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if (Instruction *IV =
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foldSelectExtConst(*Builder, SI, FI, *C, false, IsSExt))
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return IV;
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}
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}
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// See if we can fold the select into one of our operands.
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// See if we can fold the select into one of our operands.
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if (SelType->isIntOrIntVectorTy() || SelType->isFPOrFPVectorTy()) {
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if (SelType->isIntOrIntVectorTy() || SelType->isFPOrFPVectorTy()) {
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if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal))
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if (Instruction *FoldI = FoldSelectIntoOp(SI, TrueVal, FalseVal))
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@ -790,7 +790,7 @@ Instruction *InstCombiner::FoldOpIntoSelect(Instruction &Op, SelectInst *SI) {
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if (isa<Constant>(TV) || isa<Constant>(FV)) {
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if (isa<Constant>(TV) || isa<Constant>(FV)) {
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// Bool selects with constant operands can be folded to logical ops.
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// Bool selects with constant operands can be folded to logical ops.
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if (SI->getType()->isIntegerTy(1)) return nullptr;
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if (SI->getType()->getScalarType()->isIntegerTy(1)) return nullptr;
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// If it's a bitcast involving vectors, make sure it has the same number of
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// If it's a bitcast involving vectors, make sure it has the same number of
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// elements on both sides.
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// elements on both sides.
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@ -3,8 +3,8 @@
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define i32 @test_sext1(i1 %cca, i1 %ccb) {
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define i32 @test_sext1(i1 %cca, i1 %ccb) {
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; CHECK-LABEL: @test_sext1(
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; CHECK-LABEL: @test_sext1(
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; CHECK-NEXT: [[CCAX:%.*]] = sext i1 %cca to i32
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; CHECK-NEXT: [[FOLD_R:%.*]] = and i1 %ccb, %cca
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; CHECK-NEXT: [[R:%.*]] = select i1 %ccb, i32 [[CCAX]], i32 0
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; CHECK-NEXT: [[R:%.*]] = sext i1 [[FOLD_R]] to i32
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; CHECK-NEXT: ret i32 [[R]]
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; CHECK-NEXT: ret i32 [[R]]
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;
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;
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%ccax = sext i1 %cca to i32
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%ccax = sext i1 %cca to i32
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@ -14,8 +14,8 @@ define i32 @test_sext1(i1 %cca, i1 %ccb) {
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define i32 @test_sext2(i1 %cca, i1 %ccb) {
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define i32 @test_sext2(i1 %cca, i1 %ccb) {
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; CHECK-LABEL: @test_sext2(
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; CHECK-LABEL: @test_sext2(
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; CHECK-NEXT: [[CCAX:%.*]] = sext i1 %cca to i32
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; CHECK-NEXT: [[FOLD_R:%.*]] = or i1 %ccb, %cca
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; CHECK-NEXT: [[R:%.*]] = select i1 %ccb, i32 -1, i32 [[CCAX]]
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; CHECK-NEXT: [[R:%.*]] = sext i1 [[FOLD_R]] to i32
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; CHECK-NEXT: ret i32 [[R]]
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; CHECK-NEXT: ret i32 [[R]]
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;
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;
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%ccax = sext i1 %cca to i32
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%ccax = sext i1 %cca to i32
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@ -25,8 +25,9 @@ define i32 @test_sext2(i1 %cca, i1 %ccb) {
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define i32 @test_sext3(i1 %cca, i1 %ccb) {
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define i32 @test_sext3(i1 %cca, i1 %ccb) {
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; CHECK-LABEL: @test_sext3(
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; CHECK-LABEL: @test_sext3(
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; CHECK-NEXT: [[CCAX:%.*]] = sext i1 %cca to i32
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; CHECK-NEXT: [[NOT_CCB:%.*]] = xor i1 %ccb, true
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; CHECK-NEXT: [[R:%.*]] = select i1 %ccb, i32 0, i32 [[CCAX]]
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; CHECK-NEXT: [[FOLD_R:%.*]] = and i1 [[NOT_CCB]], %cca
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; CHECK-NEXT: [[R:%.*]] = sext i1 [[FOLD_R]] to i32
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; CHECK-NEXT: ret i32 [[R]]
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; CHECK-NEXT: ret i32 [[R]]
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;
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;
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%ccax = sext i1 %cca to i32
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%ccax = sext i1 %cca to i32
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@ -36,8 +37,9 @@ define i32 @test_sext3(i1 %cca, i1 %ccb) {
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define i32 @test_sext4(i1 %cca, i1 %ccb) {
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define i32 @test_sext4(i1 %cca, i1 %ccb) {
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; CHECK-LABEL: @test_sext4(
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; CHECK-LABEL: @test_sext4(
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; CHECK-NEXT: [[CCAX:%.*]] = sext i1 %cca to i32
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; CHECK-NEXT: [[NOT_CCB:%.*]] = xor i1 %ccb, true
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; CHECK-NEXT: [[R:%.*]] = select i1 %ccb, i32 [[CCAX]], i32 -1
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; CHECK-NEXT: [[FOLD_R:%.*]] = or i1 [[NOT_CCB]], %cca
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; CHECK-NEXT: [[R:%.*]] = sext i1 [[FOLD_R]] to i32
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; CHECK-NEXT: ret i32 [[R]]
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; CHECK-NEXT: ret i32 [[R]]
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;
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;
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%ccax = sext i1 %cca to i32
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%ccax = sext i1 %cca to i32
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@ -47,8 +49,8 @@ define i32 @test_sext4(i1 %cca, i1 %ccb) {
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define i32 @test_zext1(i1 %cca, i1 %ccb) {
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define i32 @test_zext1(i1 %cca, i1 %ccb) {
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; CHECK-LABEL: @test_zext1(
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; CHECK-LABEL: @test_zext1(
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; CHECK-NEXT: [[CCAX:%.*]] = zext i1 %cca to i32
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; CHECK-NEXT: [[FOLD_R:%.*]] = and i1 %ccb, %cca
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; CHECK-NEXT: [[R:%.*]] = select i1 %ccb, i32 [[CCAX]], i32 0
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; CHECK-NEXT: [[R:%.*]] = zext i1 [[FOLD_R]] to i32
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; CHECK-NEXT: ret i32 [[R]]
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; CHECK-NEXT: ret i32 [[R]]
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;
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;
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%ccax = zext i1 %cca to i32
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%ccax = zext i1 %cca to i32
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@ -58,8 +60,8 @@ define i32 @test_zext1(i1 %cca, i1 %ccb) {
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define i32 @test_zext2(i1 %cca, i1 %ccb) {
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define i32 @test_zext2(i1 %cca, i1 %ccb) {
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; CHECK-LABEL: @test_zext2(
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; CHECK-LABEL: @test_zext2(
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; CHECK-NEXT: [[CCAX:%.*]] = zext i1 %cca to i32
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; CHECK-NEXT: [[FOLD_R:%.*]] = or i1 %ccb, %cca
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; CHECK-NEXT: [[R:%.*]] = select i1 %ccb, i32 1, i32 [[CCAX]]
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; CHECK-NEXT: [[R:%.*]] = zext i1 [[FOLD_R]] to i32
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; CHECK-NEXT: ret i32 [[R]]
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; CHECK-NEXT: ret i32 [[R]]
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;
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;
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%ccax = zext i1 %cca to i32
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%ccax = zext i1 %cca to i32
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@ -69,8 +71,9 @@ define i32 @test_zext2(i1 %cca, i1 %ccb) {
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define i32 @test_zext3(i1 %cca, i1 %ccb) {
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define i32 @test_zext3(i1 %cca, i1 %ccb) {
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; CHECK-LABEL: @test_zext3(
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; CHECK-LABEL: @test_zext3(
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; CHECK-NEXT: [[CCAX:%.*]] = zext i1 %cca to i32
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; CHECK-NEXT: [[NOT_CCB:%.*]] = xor i1 %ccb, true
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; CHECK-NEXT: [[R:%.*]] = select i1 %ccb, i32 0, i32 [[CCAX]]
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; CHECK-NEXT: [[FOLD_R:%.*]] = and i1 [[NOT_CCB]], %cca
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; CHECK-NEXT: [[R:%.*]] = zext i1 [[FOLD_R]] to i32
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; CHECK-NEXT: ret i32 [[R]]
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; CHECK-NEXT: ret i32 [[R]]
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;
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;
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%ccax = zext i1 %cca to i32
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%ccax = zext i1 %cca to i32
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@ -80,8 +83,9 @@ define i32 @test_zext3(i1 %cca, i1 %ccb) {
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define i32 @test_zext4(i1 %cca, i1 %ccb) {
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define i32 @test_zext4(i1 %cca, i1 %ccb) {
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; CHECK-LABEL: @test_zext4(
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; CHECK-LABEL: @test_zext4(
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; CHECK-NEXT: [[CCAX:%.*]] = zext i1 %cca to i32
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; CHECK-NEXT: [[NOT_CCB:%.*]] = xor i1 %ccb, true
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; CHECK-NEXT: [[R:%.*]] = select i1 %ccb, i32 [[CCAX]], i32 1
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; CHECK-NEXT: [[FOLD_R:%.*]] = or i1 [[NOT_CCB]], %cca
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; CHECK-NEXT: [[R:%.*]] = zext i1 [[FOLD_R]] to i32
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; CHECK-NEXT: ret i32 [[R]]
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; CHECK-NEXT: ret i32 [[R]]
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;
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;
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%ccax = zext i1 %cca to i32
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%ccax = zext i1 %cca to i32
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@ -151,10 +155,10 @@ define i32 @test_op_op(i32 %a, i32 %b, i32 %c) {
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ret i32 %r
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ret i32 %r
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}
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}
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define <2 x i32> @test_vectors1(<2 x i1> %cca, <2 x i1> %ccb) {
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define <2 x i32> @test_vectors_sext(<2 x i1> %cca, <2 x i1> %ccb) {
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; CHECK-LABEL: @test_vectors1(
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; CHECK-LABEL: @test_vectors_sext(
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; CHECK-NEXT: [[CCAX:%.*]] = sext <2 x i1> %cca to <2 x i32>
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; CHECK-NEXT: [[FOLD_R:%.*]] = and <2 x i1> %ccb, %cca
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; CHECK-NEXT: [[R:%.*]] = select <2 x i1> %ccb, <2 x i32> [[CCAX]], <2 x i32> zeroinitializer
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; CHECK-NEXT: [[R:%.*]] = sext <2 x i1> [[FOLD_R]] to <2 x i32>
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; CHECK-NEXT: ret <2 x i32> [[R]]
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; CHECK-NEXT: ret <2 x i32> [[R]]
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;
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;
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%ccax = sext <2 x i1> %cca to <2 x i32>
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%ccax = sext <2 x i1> %cca to <2 x i32>
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@ -162,13 +166,35 @@ define <2 x i32> @test_vectors1(<2 x i1> %cca, <2 x i1> %ccb) {
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ret <2 x i32> %r
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ret <2 x i32> %r
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}
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}
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define <2 x i32> @test_vectors2(<2 x i1> %cca, i1 %ccb) {
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define <2 x i32> @test_vectors_zext(<2 x i1> %cca, <2 x i1> %ccb) {
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; CHECK-LABEL: @test_vectors2(
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; CHECK-LABEL: @test_vectors_zext(
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; CHECK-NEXT: [[CCAX:%.*]] = sext <2 x i1> %cca to <2 x i32>
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; CHECK-NEXT: [[FOLD_R:%.*]] = and <2 x i1> %ccb, %cca
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; CHECK-NEXT: [[R:%.*]] = select i1 %ccb, <2 x i32> [[CCAX]], <2 x i32> zeroinitializer
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; CHECK-NEXT: [[R:%.*]] = zext <2 x i1> [[FOLD_R]] to <2 x i32>
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; CHECK-NEXT: ret <2 x i32> [[R]]
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;
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%ccax = zext <2 x i1> %cca to <2 x i32>
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%r = select <2 x i1> %ccb, <2 x i32> %ccax, <2 x i32> <i32 0, i32 0>
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ret <2 x i32> %r
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}
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define <2 x i32> @scalar_select_of_vectors_sext(<2 x i1> %cca, i1 %ccb) {
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; CHECK-LABEL: @scalar_select_of_vectors_sext(
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; CHECK-NEXT: [[FOLD_R:%.*]] = select i1 %ccb, <2 x i1> %cca, <2 x i1> zeroinitializer
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; CHECK-NEXT: [[R:%.*]] = sext <2 x i1> [[FOLD_R]] to <2 x i32>
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; CHECK-NEXT: ret <2 x i32> [[R]]
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; CHECK-NEXT: ret <2 x i32> [[R]]
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;
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;
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%ccax = sext <2 x i1> %cca to <2 x i32>
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%ccax = sext <2 x i1> %cca to <2 x i32>
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%r = select i1 %ccb, <2 x i32> %ccax, <2 x i32> <i32 0, i32 0>
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%r = select i1 %ccb, <2 x i32> %ccax, <2 x i32> <i32 0, i32 0>
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ret <2 x i32> %r
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ret <2 x i32> %r
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}
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}
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define <2 x i32> @scalar_select_of_vectors_zext(<2 x i1> %cca, i1 %ccb) {
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; CHECK-LABEL: @scalar_select_of_vectors_zext(
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; CHECK-NEXT: [[FOLD_R:%.*]] = select i1 %ccb, <2 x i1> %cca, <2 x i1> zeroinitializer
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; CHECK-NEXT: [[R:%.*]] = zext <2 x i1> [[FOLD_R]] to <2 x i32>
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; CHECK-NEXT: ret <2 x i32> [[R]]
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;
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%ccax = zext <2 x i1> %cca to <2 x i32>
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%r = select i1 %ccb, <2 x i32> %ccax, <2 x i32> <i32 0, i32 0>
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ret <2 x i32> %r
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}
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@ -63,9 +63,8 @@ entry:
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ret <2 x i64> %conv
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ret <2 x i64> %conv
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; CHECK-LABEL: @test5(
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; CHECK-LABEL: @test5(
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; CHECK: sext <4 x i1> %cmp to <4 x i32>
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; CHECK: %fold.and = and <4 x i1> %cmp4, %cmp
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; The sext-and pair is canonicalized to a select.
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; CHECK: sext <4 x i1> %fold.and to <4 x i32>
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; CHECK: select <4 x i1> %cmp4, <4 x i32> %sext, <4 x i32> zeroinitializer
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}
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}
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