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release/20.x: [InstCombine] Fix FMF propagation in foldSelectWithFCmpToFabs (#121580) #125338

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Feb 7, 2025
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release/20.x: [InstCombine] Fix FMF propagation in foldSelectWithFCmpToFabs (#121580) #125338

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11 changes: 9 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 @@ -2852,10 +2852,10 @@ static Instruction *foldSelectWithFCmpToFabs(SelectInst &SI,
if (!match(TrueVal, m_FNeg(m_Specific(X))))
return nullptr;

// Forward-propagate nnan and ninf from the fneg to the select.
// Forward-propagate nnan and ninf from the fcmp to the select.
// If all inputs are not those values, then the select is not either.
// Note: nsz is defined differently, so it may not be correct to propagate.
FastMathFlags FMF = cast<FPMathOperator>(TrueVal)->getFastMathFlags();
FastMathFlags FMF = cast<FPMathOperator>(CondVal)->getFastMathFlags();
if (FMF.noNaNs() && !SI.hasNoNaNs()) {
SI.setHasNoNaNs(true);
ChangedFMF = true;
Expand All @@ -2864,6 +2864,13 @@ static Instruction *foldSelectWithFCmpToFabs(SelectInst &SI,
SI.setHasNoInfs(true);
ChangedFMF = true;
}
// Forward-propagate nnan from the fneg to the select.
// The nnan flag can be propagated iff fneg is selected when X is NaN.
if (!SI.hasNoNaNs() && cast<FPMathOperator>(TrueVal)->hasNoNaNs() &&
(Swap ? FCmpInst::isOrdered(Pred) : FCmpInst::isUnordered(Pred))) {
SI.setHasNoNaNs(true);
ChangedFMF = true;
}

// With nsz, when 'Swap' is false:
// fold (X < +/-0.0) ? -X : X or (X <= +/-0.0) ? -X : X to fabs(X)
Expand Down
40 changes: 20 additions & 20 deletions llvm/test/Transforms/InstCombine/fabs.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -484,7 +484,7 @@ define double @select_fcmp_nnan_nsz_olt_zero(double %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_olt_zero(
; CHECK-NEXT: [[LTZERO:%.*]] = fcmp olt double [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[NEGX:%.*]] = fneg nnan nsz double [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan i1 [[LTZERO]], double [[NEGX]], double [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select i1 [[LTZERO]], double [[NEGX]], double [[X]]
; CHECK-NEXT: ret double [[FABS]]
;
%ltzero = fcmp olt double %x, 0.0
Expand Down Expand Up @@ -523,7 +523,7 @@ define double @select_fcmp_nnan_nsz_olt_zero_unary_fneg(double %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_olt_zero_unary_fneg(
; CHECK-NEXT: [[LTZERO:%.*]] = fcmp olt double [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[NEGX:%.*]] = fneg nnan nsz double [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan i1 [[LTZERO]], double [[NEGX]], double [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select i1 [[LTZERO]], double [[NEGX]], double [[X]]
; CHECK-NEXT: ret double [[FABS]]
;
%ltzero = fcmp olt double %x, 0.0
Expand Down Expand Up @@ -553,7 +553,7 @@ define float @select_fcmp_nnan_nsz_olt_negzero(float %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_olt_negzero(
; CHECK-NEXT: [[LTZERO:%.*]] = fcmp olt float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[NEGX:%.*]] = fneg nnan ninf nsz float [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan ninf i1 [[LTZERO]], float [[NEGX]], float [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select i1 [[LTZERO]], float [[NEGX]], float [[X]]
; CHECK-NEXT: ret float [[FABS]]
;
%ltzero = fcmp olt float %x, -0.0
Expand All @@ -579,7 +579,7 @@ define float @select_fcmp_nnan_nsz_ult_negzero(float %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_ult_negzero(
; CHECK-NEXT: [[LTZERO:%.*]] = fcmp ult float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[NEGX:%.*]] = fneg nnan ninf nsz float [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan ninf i1 [[LTZERO]], float [[NEGX]], float [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan i1 [[LTZERO]], float [[NEGX]], float [[X]]
; CHECK-NEXT: ret float [[FABS]]
;
%ltzero = fcmp ult float %x, -0.0
Expand All @@ -592,7 +592,7 @@ define float @select_fcmp_nnan_nsz_olt_negzero_unary_fneg(float %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_olt_negzero_unary_fneg(
; CHECK-NEXT: [[LTZERO:%.*]] = fcmp olt float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[NEGX:%.*]] = fneg nnan ninf nsz float [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan ninf i1 [[LTZERO]], float [[NEGX]], float [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select i1 [[LTZERO]], float [[NEGX]], float [[X]]
; CHECK-NEXT: ret float [[FABS]]
;
%ltzero = fcmp olt float %x, -0.0
Expand All @@ -607,7 +607,7 @@ define float @select_fcmp_nnan_nsz_ult_negzero_unary_fneg(float %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_ult_negzero_unary_fneg(
; CHECK-NEXT: [[LTZERO:%.*]] = fcmp ult float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[NEGX:%.*]] = fneg nnan ninf nsz float [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan ninf i1 [[LTZERO]], float [[NEGX]], float [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan i1 [[LTZERO]], float [[NEGX]], float [[X]]
; CHECK-NEXT: ret float [[FABS]]
;
%ltzero = fcmp ult float %x, -0.0
Expand All @@ -622,7 +622,7 @@ define double @select_fcmp_nnan_nsz_ole_zero(double %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_ole_zero(
; CHECK-NEXT: [[LEZERO:%.*]] = fcmp ole double [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[NEGX:%.*]] = fneg fast double [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan ninf i1 [[LEZERO]], double [[NEGX]], double [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select i1 [[LEZERO]], double [[NEGX]], double [[X]]
; CHECK-NEXT: ret double [[FABS]]
;
%lezero = fcmp ole double %x, 0.0
Expand All @@ -648,7 +648,7 @@ define double @select_fcmp_nnan_nsz_ule_zero(double %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_ule_zero(
; CHECK-NEXT: [[LEZERO:%.*]] = fcmp ule double [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[NEGX:%.*]] = fneg fast double [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan ninf i1 [[LEZERO]], double [[NEGX]], double [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan i1 [[LEZERO]], double [[NEGX]], double [[X]]
; CHECK-NEXT: ret double [[FABS]]
;
%lezero = fcmp ule double %x, 0.0
Expand All @@ -661,7 +661,7 @@ define double @select_fcmp_nnan_nsz_ole_zero_unary_fneg(double %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_ole_zero_unary_fneg(
; CHECK-NEXT: [[LEZERO:%.*]] = fcmp ole double [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[NEGX:%.*]] = fneg fast double [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan ninf i1 [[LEZERO]], double [[NEGX]], double [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select i1 [[LEZERO]], double [[NEGX]], double [[X]]
; CHECK-NEXT: ret double [[FABS]]
;
%lezero = fcmp ole double %x, 0.0
Expand All @@ -676,7 +676,7 @@ define double @select_fcmp_nnan_nsz_ule_zero_unary_fneg(double %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_ule_zero_unary_fneg(
; CHECK-NEXT: [[LEZERO:%.*]] = fcmp ule double [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[NEGX:%.*]] = fneg fast double [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan ninf i1 [[LEZERO]], double [[NEGX]], double [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan i1 [[LEZERO]], double [[NEGX]], double [[X]]
; CHECK-NEXT: ret double [[FABS]]
;
%lezero = fcmp ule double %x, 0.0
Expand All @@ -691,7 +691,7 @@ define float @select_fcmp_nnan_nsz_ole_negzero(float %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_ole_negzero(
; CHECK-NEXT: [[LEZERO:%.*]] = fcmp ole float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[NEGX:%.*]] = fneg nnan nsz float [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan i1 [[LEZERO]], float [[NEGX]], float [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select i1 [[LEZERO]], float [[NEGX]], float [[X]]
; CHECK-NEXT: ret float [[FABS]]
;
%lezero = fcmp ole float %x, -0.0
Expand Down Expand Up @@ -730,7 +730,7 @@ define float @select_fcmp_nnan_nsz_ole_negzero_unary_fneg(float %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_ole_negzero_unary_fneg(
; CHECK-NEXT: [[LEZERO:%.*]] = fcmp ole float [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[NEGX:%.*]] = fneg nnan nsz float [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan i1 [[LEZERO]], float [[NEGX]], float [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select i1 [[LEZERO]], float [[NEGX]], float [[X]]
; CHECK-NEXT: ret float [[FABS]]
;
%lezero = fcmp ole float %x, -0.0
Expand Down Expand Up @@ -802,7 +802,7 @@ define <2 x float> @select_fcmp_nnan_nsz_ugt_zero(<2 x float> %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_ugt_zero(
; CHECK-NEXT: [[GTZERO:%.*]] = fcmp ugt <2 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: [[NEGX:%.*]] = fneg nnan nsz arcp <2 x float> [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan <2 x i1> [[GTZERO]], <2 x float> [[X]], <2 x float> [[NEGX]]
; CHECK-NEXT: [[FABS:%.*]] = select <2 x i1> [[GTZERO]], <2 x float> [[X]], <2 x float> [[NEGX]]
; CHECK-NEXT: ret <2 x float> [[FABS]]
;
%gtzero = fcmp ugt <2 x float> %x, zeroinitializer
Expand Down Expand Up @@ -830,7 +830,7 @@ define <2 x float> @select_fcmp_nnan_nsz_ugt_zero_unary_fneg(<2 x float> %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_ugt_zero_unary_fneg(
; CHECK-NEXT: [[GTZERO:%.*]] = fcmp ugt <2 x float> [[X:%.*]], zeroinitializer
; CHECK-NEXT: [[NEGX:%.*]] = fneg nnan nsz arcp <2 x float> [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan <2 x i1> [[GTZERO]], <2 x float> [[X]], <2 x float> [[NEGX]]
; CHECK-NEXT: [[FABS:%.*]] = select <2 x i1> [[GTZERO]], <2 x float> [[X]], <2 x float> [[NEGX]]
; CHECK-NEXT: ret <2 x float> [[FABS]]
;
%gtzero = fcmp ugt <2 x float> %x, zeroinitializer
Expand All @@ -845,7 +845,7 @@ define half @select_fcmp_nnan_nsz_ogt_negzero(half %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_ogt_negzero(
; CHECK-NEXT: [[GTZERO:%.*]] = fcmp ogt half [[X:%.*]], 0xH0000
; CHECK-NEXT: [[NEGX:%.*]] = fneg fast half [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan ninf i1 [[GTZERO]], half [[X]], half [[NEGX]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan i1 [[GTZERO]], half [[X]], half [[NEGX]]
; CHECK-NEXT: ret half [[FABS]]
;
%gtzero = fcmp ogt half %x, -0.0
Expand All @@ -860,7 +860,7 @@ define half @select_fcmp_nnan_nsz_ugt_negzero(half %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_ugt_negzero(
; CHECK-NEXT: [[GTZERO:%.*]] = fcmp ugt half [[X:%.*]], 0xH0000
; CHECK-NEXT: [[NEGX:%.*]] = fneg fast half [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan ninf i1 [[GTZERO]], half [[X]], half [[NEGX]]
; CHECK-NEXT: [[FABS:%.*]] = select i1 [[GTZERO]], half [[X]], half [[NEGX]]
; CHECK-NEXT: ret half [[FABS]]
;
%gtzero = fcmp ugt half %x, -0.0
Expand Down Expand Up @@ -890,7 +890,7 @@ define <2 x double> @select_fcmp_nnan_nsz_uge_zero(<2 x double> %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_uge_zero(
; CHECK-NEXT: [[GEZERO:%.*]] = fcmp uge <2 x double> [[X:%.*]], zeroinitializer
; CHECK-NEXT: [[NEGX:%.*]] = fneg reassoc nnan nsz <2 x double> [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan <2 x i1> [[GEZERO]], <2 x double> [[X]], <2 x double> [[NEGX]]
; CHECK-NEXT: [[FABS:%.*]] = select <2 x i1> [[GEZERO]], <2 x double> [[X]], <2 x double> [[NEGX]]
; CHECK-NEXT: ret <2 x double> [[FABS]]
;
%gezero = fcmp uge <2 x double> %x, zeroinitializer
Expand Down Expand Up @@ -918,7 +918,7 @@ define <2 x double> @select_fcmp_nnan_nsz_uge_zero_unary_fneg(<2 x double> %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_uge_zero_unary_fneg(
; CHECK-NEXT: [[GEZERO:%.*]] = fcmp uge <2 x double> [[X:%.*]], zeroinitializer
; CHECK-NEXT: [[NEGX:%.*]] = fneg reassoc nnan nsz <2 x double> [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan <2 x i1> [[GEZERO]], <2 x double> [[X]], <2 x double> [[NEGX]]
; CHECK-NEXT: [[FABS:%.*]] = select <2 x i1> [[GEZERO]], <2 x double> [[X]], <2 x double> [[NEGX]]
; CHECK-NEXT: ret <2 x double> [[FABS]]
;
%gezero = fcmp uge <2 x double> %x, zeroinitializer
Expand Down Expand Up @@ -948,7 +948,7 @@ define half @select_fcmp_nnan_nsz_uge_negzero(half %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_uge_negzero(
; CHECK-NEXT: [[GEZERO:%.*]] = fcmp uge half [[X:%.*]], 0xH0000
; CHECK-NEXT: [[NEGX:%.*]] = fneg nnan nsz half [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan i1 [[GEZERO]], half [[X]], half [[NEGX]]
; CHECK-NEXT: [[FABS:%.*]] = select i1 [[GEZERO]], half [[X]], half [[NEGX]]
; CHECK-NEXT: ret half [[FABS]]
;
%gezero = fcmp uge half %x, -0.0
Expand Down Expand Up @@ -976,7 +976,7 @@ define half @select_fcmp_nnan_nsz_uge_negzero_unary_fneg(half %x) {
; CHECK-LABEL: @select_fcmp_nnan_nsz_uge_negzero_unary_fneg(
; CHECK-NEXT: [[GEZERO:%.*]] = fcmp uge half [[X:%.*]], 0xH0000
; CHECK-NEXT: [[NEGX:%.*]] = fneg nnan nsz half [[X]]
; CHECK-NEXT: [[FABS:%.*]] = select nnan i1 [[GEZERO]], half [[X]], half [[NEGX]]
; CHECK-NEXT: [[FABS:%.*]] = select i1 [[GEZERO]], half [[X]], half [[NEGX]]
; CHECK-NEXT: ret half [[FABS]]
;
%gezero = fcmp uge half %x, -0.0
Expand Down
17 changes: 9 additions & 8 deletions llvm/test/Transforms/InstCombine/fneg-fabs.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -20,8 +20,8 @@ define double @select_noFMF_nfabs_lt(double %x) {
; One test where the neg has fmfs.
define double @select_nsz_nfabs_lt_fmfProp(double %x) {
; CHECK-LABEL: @select_nsz_nfabs_lt_fmfProp(
; CHECK-NEXT: [[TMP1:%.*]] = call nnan ninf nsz double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: [[SEL:%.*]] = fneg nnan ninf nsz double [[TMP1]]
; CHECK-NEXT: [[TMP1:%.*]] = call nnan nsz double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: [[SEL:%.*]] = fneg nnan nsz double [[TMP1]]
; CHECK-NEXT: ret double [[SEL]]
;
%cmp = fcmp olt double %x, 0.000000e+00
Expand All @@ -32,8 +32,8 @@ define double @select_nsz_nfabs_lt_fmfProp(double %x) {

define double @select_nsz_nnan_nfabs_lt_fmfProp(double %x) {
; CHECK-LABEL: @select_nsz_nnan_nfabs_lt_fmfProp(
; CHECK-NEXT: [[TMP1:%.*]] = call nnan ninf nsz double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: [[SEL:%.*]] = fneg nnan ninf nsz double [[TMP1]]
; CHECK-NEXT: [[TMP1:%.*]] = call nnan nsz double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: [[SEL:%.*]] = fneg nnan nsz double [[TMP1]]
; CHECK-NEXT: ret double [[SEL]]
;
%cmp = fcmp olt double %x, 0.000000e+00
Expand Down Expand Up @@ -147,8 +147,9 @@ define double @select_noFMF_nfabs_gt(double %x) {
; One test where the neg has fmfs.
define double @select_nsz_nfabs_gt_fmfProp(double %x) {
; CHECK-LABEL: @select_nsz_nfabs_gt_fmfProp(
; CHECK-NEXT: [[TMP1:%.*]] = call nnan ninf nsz double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: [[SEL:%.*]] = fneg nnan ninf nsz double [[TMP1]]
; CHECK-NEXT: [[CMP:%.*]] = fcmp ogt double [[X:%.*]], 0.000000e+00
; CHECK-NEXT: [[NEGX:%.*]] = fneg fast double [[X]]
; CHECK-NEXT: [[SEL:%.*]] = select nsz i1 [[CMP]], double [[NEGX]], double [[X]]
; CHECK-NEXT: ret double [[SEL]]
;
%cmp = fcmp ogt double %x, 0.000000e+00
Expand All @@ -159,8 +160,8 @@ define double @select_nsz_nfabs_gt_fmfProp(double %x) {

define double @select_nsz_nnan_nfabs_gt_fmfProp(double %x) {
; CHECK-LABEL: @select_nsz_nnan_nfabs_gt_fmfProp(
; CHECK-NEXT: [[TMP1:%.*]] = call nnan ninf nsz double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: [[SEL:%.*]] = fneg nnan ninf nsz double [[TMP1]]
; CHECK-NEXT: [[TMP1:%.*]] = call nnan nsz double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: [[SEL:%.*]] = fneg nnan nsz double [[TMP1]]
; CHECK-NEXT: ret double [[SEL]]
;
%cmp = fcmp ogt double %x, 0.000000e+00
Expand Down
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