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[InstCombine] Propagate FMF from select instead of fcmp #141010

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Merged
merged 4 commits into from
May 31, 2025
Merged

[InstCombine] Propagate FMF from select instead of fcmp #141010

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4b9bb28
[InstCombine] Propagate FMF from select instead of fcmp
dtcxzyw May 22, 2025
25ebc0b
[InstCombine] Propagate ninf/nnan from fcmp to select.
dtcxzyw May 29, 2025
a461c83
[InstCombine] Update tests. NFC.
dtcxzyw May 29, 2025
2c09b5c
[InstCombine] Update test. NFC.
dtcxzyw May 30, 2025
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10 changes: 8 additions & 2 deletions llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/FMF.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/InstrTypes.h"
#include "llvm/IR/Instruction.h"
Expand Down Expand Up @@ -3879,11 +3880,16 @@ Instruction *InstCombinerImpl::visitSelectInst(SelectInst &SI) {
// (X ugt Y) ? X : Y -> (X ole Y) ? Y : X
if (FCmp->hasOneUse() && FCmpInst::isUnordered(Pred)) {
FCmpInst::Predicate InvPred = FCmp->getInversePredicate();
// FIXME: The FMF should propagate from the select, not the fcmp.
Value *NewCond = Builder.CreateFCmpFMF(InvPred, Cmp0, Cmp1, FCmp,
FCmp->getName() + ".inv");
// Propagate ninf/nnan from fcmp to select.
FastMathFlags FMF = SI.getFastMathFlags();
if (FCmp->hasNoNaNs())
FMF.setNoNaNs(true);
if (FCmp->hasNoInfs())
FMF.setNoInfs(true);
Value *NewSel =
Builder.CreateSelectFMF(NewCond, FalseVal, TrueVal, FCmp);
Builder.CreateSelectFMF(NewCond, FalseVal, TrueVal, FMF);
return replaceInstUsesWith(SI, NewSel);
}
}
Expand Down
53 changes: 32 additions & 21 deletions llvm/test/Transforms/InstCombine/clamp-to-minmax.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,8 @@ define float @clamp_float_fast_ordered_strict_maxmin(float %x) {
; CHECK-LABEL: @clamp_float_fast_ordered_strict_maxmin(
; CHECK-NEXT: [[CMP2:%.*]] = fcmp fast olt float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[MIN:%.*]] = select i1 [[CMP2]], float [[X]], float 2.550000e+02
; CHECK-NEXT: [[R1:%.*]] = call fast float @llvm.maxnum.f32(float [[MIN]], float 1.000000e+00)
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast oge float [[MIN]], 1.000000e+00
; CHECK-NEXT: [[R1:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MIN]], float 1.000000e+00
; CHECK-NEXT: ret float [[R1]]
;
%cmp2 = fcmp fast olt float %x, 255.0
Expand All @@ -22,7 +23,8 @@ define float @clamp_float_fast_ordered_nonstrict_maxmin(float %x) {
; CHECK-LABEL: @clamp_float_fast_ordered_nonstrict_maxmin(
; CHECK-NEXT: [[CMP2:%.*]] = fcmp fast olt float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[MIN:%.*]] = select i1 [[CMP2]], float [[X]], float 2.550000e+02
; CHECK-NEXT: [[R1:%.*]] = call fast float @llvm.maxnum.f32(float [[MIN]], float 1.000000e+00)
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast oge float [[MIN]], 1.000000e+00
; CHECK-NEXT: [[R1:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MIN]], float 1.000000e+00
; CHECK-NEXT: ret float [[R1]]
;
%cmp2 = fcmp fast olt float %x, 255.0
Expand All @@ -37,7 +39,8 @@ define float @clamp_float_fast_ordered_strict_minmax(float %x) {
; CHECK-LABEL: @clamp_float_fast_ordered_strict_minmax(
; CHECK-NEXT: [[CMP2:%.*]] = fcmp fast ogt float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[MAX:%.*]] = select i1 [[CMP2]], float [[X]], float 1.000000e+00
; CHECK-NEXT: [[R1:%.*]] = call fast float @llvm.minnum.f32(float [[MAX]], float 2.550000e+02)
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast ole float [[MAX]], 2.550000e+02
; CHECK-NEXT: [[R1:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MAX]], float 2.550000e+02
; CHECK-NEXT: ret float [[R1]]
;
%cmp2 = fcmp fast ogt float %x, 1.0
Expand All @@ -52,7 +55,8 @@ define float @clamp_float_fast_ordered_nonstrict_minmax(float %x) {
; CHECK-LABEL: @clamp_float_fast_ordered_nonstrict_minmax(
; CHECK-NEXT: [[CMP2:%.*]] = fcmp fast ogt float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[MAX:%.*]] = select i1 [[CMP2]], float [[X]], float 1.000000e+00
; CHECK-NEXT: [[R1:%.*]] = call fast float @llvm.minnum.f32(float [[MAX]], float 2.550000e+02)
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast ole float [[MAX]], 2.550000e+02
; CHECK-NEXT: [[R1:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MAX]], float 2.550000e+02
; CHECK-NEXT: ret float [[R1]]
;
%cmp2 = fcmp fast ogt float %x, 1.0
Expand All @@ -68,9 +72,10 @@ define float @clamp_float_fast_ordered_nonstrict_minmax(float %x) {
; (X < C1) ? C1 : MIN(X, C2)
define float @clamp_float_fast_unordered_strict_maxmin(float %x) {
; CHECK-LABEL: @clamp_float_fast_unordered_strict_maxmin(
; CHECK-NEXT: [[MIN:%.*]] = call fast float @llvm.minnum.f32(float [[X:%.*]], float 2.550000e+02)
; CHECK-NEXT: [[CMP1:%.*]] = fcmp fast ult float [[X]], 1.000000e+00
; CHECK-NEXT: [[R:%.*]] = select i1 [[CMP1]], float 1.000000e+00, float [[MIN]]
; CHECK-NEXT: [[CMP2_INV:%.*]] = fcmp fast oge float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[MIN:%.*]] = select nnan ninf i1 [[CMP2_INV]], float 2.550000e+02, float [[X]]
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast oge float [[MIN]], 1.000000e+00
; CHECK-NEXT: [[R:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MIN]], float 1.000000e+00
; CHECK-NEXT: ret float [[R]]
;
%cmp2 = fcmp fast ult float %x, 255.0
Expand All @@ -83,9 +88,10 @@ define float @clamp_float_fast_unordered_strict_maxmin(float %x) {
; (X <= C1) ? C1 : MIN(X, C2)
define float @clamp_float_fast_unordered_nonstrict_maxmin(float %x) {
; CHECK-LABEL: @clamp_float_fast_unordered_nonstrict_maxmin(
; CHECK-NEXT: [[MIN:%.*]] = call fast float @llvm.minnum.f32(float [[X:%.*]], float 2.550000e+02)
; CHECK-NEXT: [[CMP1:%.*]] = fcmp fast ule float [[X]], 1.000000e+00
; CHECK-NEXT: [[R:%.*]] = select i1 [[CMP1]], float 1.000000e+00, float [[MIN]]
; CHECK-NEXT: [[CMP2_INV:%.*]] = fcmp fast oge float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[MIN:%.*]] = select nnan ninf i1 [[CMP2_INV]], float 2.550000e+02, float [[X]]
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast oge float [[MIN]], 1.000000e+00
; CHECK-NEXT: [[R:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MIN]], float 1.000000e+00
; CHECK-NEXT: ret float [[R]]
;
%cmp2 = fcmp fast ult float %x, 255.0
Expand All @@ -98,9 +104,10 @@ define float @clamp_float_fast_unordered_nonstrict_maxmin(float %x) {
; (X > C1) ? C1 : MAX(X, C2)
define float @clamp_float_fast_unordered_strict_minmax(float %x) {
; CHECK-LABEL: @clamp_float_fast_unordered_strict_minmax(
; CHECK-NEXT: [[MAX:%.*]] = call fast float @llvm.maxnum.f32(float [[X:%.*]], float 1.000000e+00)
; CHECK-NEXT: [[CMP1:%.*]] = fcmp fast ugt float [[X]], 2.550000e+02
; CHECK-NEXT: [[R:%.*]] = select i1 [[CMP1]], float 2.550000e+02, float [[MAX]]
; CHECK-NEXT: [[CMP2_INV:%.*]] = fcmp fast ole float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[MAX:%.*]] = select nnan ninf i1 [[CMP2_INV]], float 1.000000e+00, float [[X]]
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast ole float [[MAX]], 2.550000e+02
; CHECK-NEXT: [[R:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MAX]], float 2.550000e+02
; CHECK-NEXT: ret float [[R]]
;
%cmp2 = fcmp fast ugt float %x, 1.0
Expand All @@ -113,9 +120,10 @@ define float @clamp_float_fast_unordered_strict_minmax(float %x) {
; (X >= C1) ? C1 : MAX(X, C2)
define float @clamp_float_fast_unordered_nonstrict_minmax(float %x) {
; CHECK-LABEL: @clamp_float_fast_unordered_nonstrict_minmax(
; CHECK-NEXT: [[MAX:%.*]] = call fast float @llvm.maxnum.f32(float [[X:%.*]], float 1.000000e+00)
; CHECK-NEXT: [[CMP1:%.*]] = fcmp fast uge float [[X]], 2.550000e+02
; CHECK-NEXT: [[R:%.*]] = select i1 [[CMP1]], float 2.550000e+02, float [[MAX]]
; CHECK-NEXT: [[CMP2_INV:%.*]] = fcmp fast ole float [[X:%.*]], 1.000000e+00
; CHECK-NEXT: [[MAX:%.*]] = select nnan ninf i1 [[CMP2_INV]], float 1.000000e+00, float [[X]]
; CHECK-NEXT: [[DOTINV:%.*]] = fcmp fast ole float [[MAX]], 2.550000e+02
; CHECK-NEXT: [[R:%.*]] = select nnan ninf i1 [[DOTINV]], float [[MAX]], float 2.550000e+02
; CHECK-NEXT: ret float [[R]]
;
%cmp2 = fcmp fast ugt float %x, 1.0
Expand All @@ -130,9 +138,10 @@ define float @clamp_float_fast_unordered_nonstrict_minmax(float %x) {
; (X > 1.0) ? min(x, 255.0) : 1.0
define float @clamp_test_1(float %x) {
; CHECK-LABEL: @clamp_test_1(
; CHECK-NEXT: [[INNER_SEL:%.*]] = call fast float @llvm.minnum.f32(float [[X:%.*]], float 2.550000e+02)
; CHECK-NEXT: [[OUTER_CMP:%.*]] = fcmp fast ugt float [[X]], 1.000000e+00
; CHECK-NEXT: [[R:%.*]] = select i1 [[OUTER_CMP]], float [[INNER_SEL]], float 1.000000e+00
; CHECK-NEXT: [[INNER_CMP_INV:%.*]] = fcmp fast oge float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[INNER_SEL:%.*]] = select nnan ninf i1 [[INNER_CMP_INV]], float 2.550000e+02, float [[X]]
; CHECK-NEXT: [[OUTER_CMP:%.*]] = fcmp fast oge float [[INNER_SEL]], 1.000000e+00
; CHECK-NEXT: [[R:%.*]] = select nnan ninf i1 [[OUTER_CMP]], float [[INNER_SEL]], float 1.000000e+00
; CHECK-NEXT: ret float [[R]]
;
%inner_cmp = fcmp fast ult float %x, 255.0
Expand All @@ -147,7 +156,8 @@ define float @clamp_test_1(float %x) {
; Like @clamp_test_1 but HighConst < LowConst
define float @clamp_negative_wrong_const(float %x) {
; CHECK-LABEL: @clamp_negative_wrong_const(
; CHECK-NEXT: [[INNER_SEL:%.*]] = call fast float @llvm.minnum.f32(float [[X:%.*]], float 2.550000e+02)
; CHECK-NEXT: [[INNER_CMP_INV:%.*]] = fcmp fast oge float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[INNER_SEL:%.*]] = select nnan ninf i1 [[INNER_CMP_INV]], float 2.550000e+02, float [[X]]
; CHECK-NEXT: [[OUTER_CMP:%.*]] = fcmp fast ugt float [[X]], 5.120000e+02
; CHECK-NEXT: [[R:%.*]] = select i1 [[OUTER_CMP]], float [[INNER_SEL]], float 5.120000e+02
; CHECK-NEXT: ret float [[R]]
Expand All @@ -162,7 +172,8 @@ define float @clamp_negative_wrong_const(float %x) {
; Like @clamp_test_1 but both are min
define float @clamp_negative_same_op(float %x) {
; CHECK-LABEL: @clamp_negative_same_op(
; CHECK-NEXT: [[INNER_SEL:%.*]] = call fast float @llvm.minnum.f32(float [[X:%.*]], float 2.550000e+02)
; CHECK-NEXT: [[INNER_CMP_INV:%.*]] = fcmp fast oge float [[X:%.*]], 2.550000e+02
; CHECK-NEXT: [[INNER_SEL:%.*]] = select nnan ninf i1 [[INNER_CMP_INV]], float 2.550000e+02, float [[X]]
; CHECK-NEXT: [[OUTER_CMP:%.*]] = fcmp fast ult float [[X]], 1.000000e+00
; CHECK-NEXT: [[R:%.*]] = select i1 [[OUTER_CMP]], float [[INNER_SEL]], float 1.000000e+00
; CHECK-NEXT: ret float [[R]]
Expand Down
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