[InstCombine] Fix constant swap case of fcmp + fadd + sel xfrm #119419
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@llvm/pr-subscribers-llvm-transforms Author: Rajat Bajpai (rajatbajpai) ChangesThe fcmp + fadd + sel => fcmp + sel + fadd xfrm performs incorrect transformation when select branch values are swapped. This change fixes this. Full diff: https://github.com/llvm/llvm-project/pull/119419.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index c7a0c35d099cc4..dcdb59f6e95368 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -3723,22 +3723,9 @@ static Value *foldSelectIntoAddConstant(SelectInst &SI,
if (!SIFOp || !SIFOp->hasNoSignedZeros() || !SIFOp->hasNoNaNs())
return nullptr;
- // select((fcmp Pred, X, 0), (fadd X, C), C)
- // => fadd((select (fcmp Pred, X, 0), X, 0), C)
- //
- // Pred := OGT, OGE, OLT, OLE, UGT, UGE, ULT, and ULE
- Instruction *FAdd;
- Constant *C;
- Value *X, *Z;
- CmpInst::Predicate Pred;
-
- // Note: OneUse check for `Cmp` is necessary because it makes sure that other
- // InstCombine folds don't undo this transformation and cause an infinite
- // loop. Furthermore, it could also increase the operation count.
- if (match(&SI, m_Select(m_OneUse(m_FCmp(Pred, m_Value(X), m_Value(Z))),
- m_OneUse(m_Instruction(FAdd)), m_Constant(C))) ||
- match(&SI, m_Select(m_OneUse(m_FCmp(Pred, m_Value(X), m_Value(Z))),
- m_Constant(C), m_OneUse(m_Instruction(FAdd))))) {
+ auto TryFoldIntoAddConstant =
+ [&Builder, &SI](CmpInst::Predicate Pred, Value *X, Value *Z,
+ Instruction *FAdd, Constant *C, bool Swapped) -> Value * {
// Only these relational predicates can be transformed into maxnum/minnum
// intrinsic.
if (!CmpInst::isRelational(Pred) || !match(Z, m_AnyZeroFP()))
@@ -3747,7 +3734,8 @@ static Value *foldSelectIntoAddConstant(SelectInst &SI,
if (!match(FAdd, m_FAdd(m_Specific(X), m_Specific(C))))
return nullptr;
- Value *NewSelect = Builder.CreateSelect(SI.getCondition(), X, Z, "", &SI);
+ Value *NewSelect = Builder.CreateSelect(SI.getCondition(), Swapped ? Z : X,
+ Swapped ? X : Z, "", &SI);
NewSelect->takeName(&SI);
Value *NewFAdd = Builder.CreateFAdd(NewSelect, C);
@@ -3762,7 +3750,26 @@ static Value *foldSelectIntoAddConstant(SelectInst &SI,
cast<Instruction>(NewSelect)->setFastMathFlags(NewFMF);
return NewFAdd;
- }
+ };
+
+ // select((fcmp Pred, X, 0), (fadd X, C), C)
+ // => fadd((select (fcmp Pred, X, 0), X, 0), C)
+ //
+ // Pred := OGT, OGE, OLT, OLE, UGT, UGE, ULT, and ULE
+ Instruction *FAdd;
+ Constant *C;
+ Value *X, *Z;
+ CmpInst::Predicate Pred;
+
+ // Note: OneUse check for `Cmp` is necessary because it makes sure that other
+ // InstCombine folds don't undo this transformation and cause an infinite
+ // loop. Furthermore, it could also increase the operation count.
+ if (match(&SI, m_Select(m_OneUse(m_FCmp(Pred, m_Value(X), m_Value(Z))),
+ m_OneUse(m_Instruction(FAdd)), m_Constant(C))))
+ return TryFoldIntoAddConstant(Pred, X, Z, FAdd, C, false);
+ else if (match(&SI, m_Select(m_OneUse(m_FCmp(Pred, m_Value(X), m_Value(Z))),
+ m_Constant(C), m_OneUse(m_Instruction(FAdd)))))
+ return TryFoldIntoAddConstant(Pred, X, Z, FAdd, C, true);
return nullptr;
}
diff --git a/llvm/test/Transforms/InstCombine/fcmp-fadd-select.ll b/llvm/test/Transforms/InstCombine/fcmp-fadd-select.ll
index 0d0af91608e7ac..15fad55db8df12 100644
--- a/llvm/test/Transforms/InstCombine/fcmp-fadd-select.ll
+++ b/llvm/test/Transforms/InstCombine/fcmp-fadd-select.ll
@@ -19,7 +19,7 @@ define float @test_fcmp_ogt_fadd_select_constant(float %in) {
define float @test_fcmp_ogt_fadd_select_constant_swapped(float %in) {
; CHECK-LABEL: define float @test_fcmp_ogt_fadd_select_constant_swapped(
; CHECK-SAME: float [[IN:%.*]]) {
-; CHECK-NEXT: [[SEL_NEW:%.*]] = call nsz float @llvm.maxnum.f32(float [[IN]], float 0.000000e+00)
+; CHECK-NEXT: [[SEL_NEW:%.*]] = call nsz float @llvm.minnum.f32(float [[IN]], float 0.000000e+00)
; CHECK-NEXT: [[ADD_NEW:%.*]] = fadd nnan nsz float [[SEL_NEW]], 1.000000e+00
; CHECK-NEXT: ret float [[ADD_NEW]]
;
@@ -87,7 +87,7 @@ define float @test_fcmp_olt_fadd_select_constant(float %in) {
define float @test_fcmp_olt_fadd_select_constant_swapped(float %in) {
; CHECK-LABEL: define float @test_fcmp_olt_fadd_select_constant_swapped(
; CHECK-SAME: float [[IN:%.*]]) {
-; CHECK-NEXT: [[SEL_NEW:%.*]] = call nsz float @llvm.minnum.f32(float [[IN]], float 0.000000e+00)
+; CHECK-NEXT: [[SEL_NEW:%.*]] = call nsz float @llvm.maxnum.f32(float [[IN]], float 0.000000e+00)
; CHECK-NEXT: [[ADD_NEW:%.*]] = fadd nnan nsz float [[SEL_NEW]], 1.000000e+00
; CHECK-NEXT: ret float [[ADD_NEW]]
;
@@ -155,7 +155,7 @@ define float @test_fcmp_oge_fadd_select_constant(float %in) {
define float @test_fcmp_oge_fadd_select_constant_swapped(float %in) {
; CHECK-LABEL: define float @test_fcmp_oge_fadd_select_constant_swapped(
; CHECK-SAME: float [[IN:%.*]]) {
-; CHECK-NEXT: [[SEL_NEW:%.*]] = call nsz float @llvm.maxnum.f32(float [[IN]], float 0.000000e+00)
+; CHECK-NEXT: [[SEL_NEW:%.*]] = call nsz float @llvm.minnum.f32(float [[IN]], float 0.000000e+00)
; CHECK-NEXT: [[ADD_NEW:%.*]] = fadd nnan nsz float [[SEL_NEW]], 1.000000e+00
; CHECK-NEXT: ret float [[ADD_NEW]]
;
@@ -223,7 +223,7 @@ define float @test_fcmp_ole_fadd_select_constant(float %in) {
define float @test_fcmp_ole_fadd_select_constant_swapped(float %in) {
; CHECK-LABEL: define float @test_fcmp_ole_fadd_select_constant_swapped(
; CHECK-SAME: float [[IN:%.*]]) {
-; CHECK-NEXT: [[SEL_NEW:%.*]] = call nsz float @llvm.minnum.f32(float [[IN]], float 0.000000e+00)
+; CHECK-NEXT: [[SEL_NEW:%.*]] = call nsz float @llvm.maxnum.f32(float [[IN]], float 0.000000e+00)
; CHECK-NEXT: [[ADD_NEW:%.*]] = fadd nnan nsz float [[SEL_NEW]], 1.000000e+00
; CHECK-NEXT: ret float [[ADD_NEW]]
;
@@ -293,7 +293,7 @@ define float @test_fcmp_ugt_fadd_select_constant_swapped(float %in) {
; CHECK-LABEL: define float @test_fcmp_ugt_fadd_select_constant_swapped(
; CHECK-SAME: float [[IN:%.*]]) {
; CHECK-NEXT: [[CMP1_INV:%.*]] = fcmp ole float [[IN]], 0.000000e+00
-; CHECK-NEXT: [[SEL_NEW:%.*]] = select i1 [[CMP1_INV]], float 0.000000e+00, float [[IN]]
+; CHECK-NEXT: [[SEL_NEW:%.*]] = select i1 [[CMP1_INV]], float [[IN]], float 0.000000e+00
; CHECK-NEXT: [[ADD_NEW:%.*]] = fadd nnan nsz float [[SEL_NEW]], 1.000000e+00
; CHECK-NEXT: ret float [[ADD_NEW]]
;
@@ -366,7 +366,7 @@ define float @test_fcmp_uge_fadd_select_constant_swapped(float %in) {
; CHECK-LABEL: define float @test_fcmp_uge_fadd_select_constant_swapped(
; CHECK-SAME: float [[IN:%.*]]) {
; CHECK-NEXT: [[CMP1_INV:%.*]] = fcmp olt float [[IN]], 0.000000e+00
-; CHECK-NEXT: [[SEL_NEW:%.*]] = select i1 [[CMP1_INV]], float 0.000000e+00, float [[IN]]
+; CHECK-NEXT: [[SEL_NEW:%.*]] = select i1 [[CMP1_INV]], float [[IN]], float 0.000000e+00
; CHECK-NEXT: [[ADD_NEW:%.*]] = fadd nnan nsz float [[SEL_NEW]], 1.000000e+00
; CHECK-NEXT: ret float [[ADD_NEW]]
;
@@ -439,7 +439,7 @@ define float @test_fcmp_ult_fadd_select_constant_swapped(float %in) {
; CHECK-LABEL: define float @test_fcmp_ult_fadd_select_constant_swapped(
; CHECK-SAME: float [[IN:%.*]]) {
; CHECK-NEXT: [[CMP1_INV:%.*]] = fcmp oge float [[IN]], 0.000000e+00
-; CHECK-NEXT: [[SEL_NEW:%.*]] = select i1 [[CMP1_INV]], float 0.000000e+00, float [[IN]]
+; CHECK-NEXT: [[SEL_NEW:%.*]] = select i1 [[CMP1_INV]], float [[IN]], float 0.000000e+00
; CHECK-NEXT: [[ADD_NEW:%.*]] = fadd nnan nsz float [[SEL_NEW]], 1.000000e+00
; CHECK-NEXT: ret float [[ADD_NEW]]
;
@@ -512,7 +512,7 @@ define float @test_fcmp_ule_fadd_select_constant_swapped(float %in) {
; CHECK-LABEL: define float @test_fcmp_ule_fadd_select_constant_swapped(
; CHECK-SAME: float [[IN:%.*]]) {
; CHECK-NEXT: [[CMP1_INV:%.*]] = fcmp ogt float [[IN]], 0.000000e+00
-; CHECK-NEXT: [[SEL_NEW:%.*]] = select i1 [[CMP1_INV]], float 0.000000e+00, float [[IN]]
+; CHECK-NEXT: [[SEL_NEW:%.*]] = select i1 [[CMP1_INV]], float [[IN]], float 0.000000e+00
; CHECK-NEXT: [[ADD_NEW:%.*]] = fadd nnan nsz float [[SEL_NEW]], 1.000000e+00
; CHECK-NEXT: ret float [[ADD_NEW]]
;
|
Contributor
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@dtcxzyw Could you please also look at this change? |
Contributor
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|
Gentle ping for review @arsenm |
arsenm
approved these changes
Dec 23, 2024
The fcmp + fadd + sel => fcmp + sel + fadd xfrm performs incorrect transformation when select branch values are swapped. This change fixes this.
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Contributor
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@dtcxzyw could you please merge this PR for me? Thank you! |
Collaborator
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/141/builds/5119 Here is the relevant piece of the build log for the reference |
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The fcmp + fadd + sel => fcmp + sel + fadd xfrm performs incorrect transformation when select branch values are swapped. This change fixes this.