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[InstCombine] Implement fcmp (fadd x, 0.0), y => fcmp x, y optimization (#88476)
This PR addresses issue #88168. It implements an optimization for the case of ``` define i1 @fcmp_fadd_zero_ugt(float %x, float %y) { %add = fadd float %x, 0.000000e+00 %cmp = fcmp ugt float %add, %y ret i1 %cmp } ``` `=>` ``` define i1 @fcmp_fadd_zero_ugt(float %x, float %y) { %cmp = fcmp ugt float %x, %y ret i1 %cmp } ``` and all other types of `fcmp` instructions (`uge`, `ogt`, etc). Proofs: `fadd x, 0.0` https://alive2.llvm.org/ce/z/7FzNnM `fsub x, 0.0` https://alive2.llvm.org/ce/z/puUxLK
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‎llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp‎

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@@ -8097,6 +8097,14 @@ Instruction *InstCombinerImpl::visitFCmpInst(FCmpInst &I) {
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return new FCmpInst(I.getSwappedPredicate(), X, NegC, "", &I);
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}
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// fcmp (fadd X, 0.0), Y --> fcmp X, Y
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if (match(Op0, m_FAdd(m_Value(X), m_AnyZeroFP())))
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return new FCmpInst(Pred, X, Op1, "", &I);
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// fcmp X, (fadd Y, 0.0) --> fcmp X, Y
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if (match(Op1, m_FAdd(m_Value(Y), m_AnyZeroFP())))
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return new FCmpInst(Pred, Op0, Y, "", &I);
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if (match(Op0, m_FPExt(m_Value(X)))) {
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// fcmp (fpext X), (fpext Y) -> fcmp X, Y
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if (match(Op1, m_FPExt(m_Value(Y))) && X->getType() == Y->getType())

‎llvm/test/Transforms/InstCombine/fcmp.ll‎

Lines changed: 202 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1284,3 +1284,205 @@ define <1 x i1> @bitcast_1vec_eq0(i32 %x) {
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%cmp = fcmp oeq <1 x float> %f, zeroinitializer
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ret <1 x i1> %cmp
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}
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; Simplify fcmp (x + 0.0), y => fcmp x, y
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define i1 @fcmp_fadd_zero_ugt(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_ugt(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp ugt float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp ugt float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_uge(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_uge(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp uge float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp uge float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_ogt(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_ogt(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp ogt float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp ogt float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_oge(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_oge(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp oge float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp oge float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_ult(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_ult(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp ult float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp ult float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_ule(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_ule(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp ule float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp ule float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_olt(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_olt(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp olt float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp olt float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_ole(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_ole(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp ole float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp ole float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_oeq(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_oeq(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp oeq float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp oeq float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_one(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_one(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp one float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp one float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_ueq(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_ueq(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp ueq float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp ueq float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_une(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_une(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp une float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp une float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_ord(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_ord(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp ord float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp ord float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_uno(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_uno(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp uno float [[ADD:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp uno float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_neg_zero(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_neg_zero(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp ugt float [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, -0.000000e+00
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%cmp = fcmp ugt float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_zero_switched(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_switched(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp ult float [[Y:%.*]], [[X:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %y, 0.000000e+00
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%cmp = fcmp ugt float %x, %add
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ret i1 %cmp
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}
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define <2 x i1> @fcmp_fadd_zero_vec(<2 x float> %x, <2 x float> %y) {
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; CHECK-LABEL: @fcmp_fadd_zero_vec(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp ugt <2 x float> [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret <2 x i1> [[CMP]]
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;
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%add = fadd <2 x float> %x, <float 0.0, float -0.0>
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%cmp = fcmp ugt <2 x float> %add, %y
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ret <2 x i1> %cmp
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}
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define i1 @fcmp_fast_fadd_fast_zero(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fast_fadd_fast_zero(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp fast ugt float [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd fast float %x, 0.000000e+00
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%cmp = fcmp fast ugt float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fast_fadd_zero(float %x, float %y) {
1471+
; CHECK-LABEL: @fcmp_fast_fadd_zero(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp fast ugt float [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd float %x, 0.000000e+00
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%cmp = fcmp fast ugt float %add, %y
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ret i1 %cmp
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}
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define i1 @fcmp_fadd_fast_zero(float %x, float %y) {
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; CHECK-LABEL: @fcmp_fadd_fast_zero(
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; CHECK-NEXT: [[CMP:%.*]] = fcmp ugt float [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: ret i1 [[CMP]]
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;
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%add = fadd fast float %x, 0.000000e+00
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%cmp = fcmp ugt float %add, %y
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ret i1 %cmp
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}

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