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[AMDGPU] Fold fmed3 when inputs include infinity #144824

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Merged
merged 2 commits into from
Jun 24, 2025
Merged

[AMDGPU] Fold fmed3 when inputs include infinity #144824

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2956b11
[AMDGPU] Fold fmed3 when inputs include infinity
fairywreath Jun 19, 2025
7062423
Merge with nan handling and add comment
fairywreath Jun 19, 2025
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40 changes: 39 additions & 1 deletion llvm/lib/Target/AMDGPU/AMDGPUInstCombineIntrinsic.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1039,7 +1039,6 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const {
const APFloat *ConstSrc1 = nullptr;
const APFloat *ConstSrc2 = nullptr;

// TODO: Also can fold to 2 operands with infinities.
if ((match(Src0, m_APFloat(ConstSrc0)) && ConstSrc0->isNaN()) ||
isa<UndefValue>(Src0)) {
switch (fpenvIEEEMode(II)) {
Expand Down Expand Up @@ -1088,6 +1087,45 @@ GCNTTIImpl::instCombineIntrinsic(InstCombiner &IC, IntrinsicInst &II) const {
case KnownIEEEMode::Unknown:
break;
}
} else if (match(Src0, m_APFloat(ConstSrc0)) && ConstSrc0->isInfinity()) {
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@arsenm arsenm Jun 19, 2025

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Can you merge this case with the nan handling above? The m_APFloat matcher already matched. If this is treated as a separate case, this should use the nicer m_Inf matcher

switch (fpenvIEEEMode(II)) {
case KnownIEEEMode::On:
V = ConstSrc0->isNegative() ? IC.Builder.CreateMinNum(Src1, Src2)
: IC.Builder.CreateMaxNum(Src1, Src2);
break;
case KnownIEEEMode::Off:
V = ConstSrc0->isNegative() ? IC.Builder.CreateMinimumNum(Src1, Src2)
: IC.Builder.CreateMaximumNum(Src1, Src2);
break;
case KnownIEEEMode::Unknown:
break;
}
} else if (match(Src1, m_APFloat(ConstSrc1)) && ConstSrc1->isInfinity()) {
switch (fpenvIEEEMode(II)) {
case KnownIEEEMode::On:
V = ConstSrc1->isNegative() ? IC.Builder.CreateMinNum(Src0, Src2)
: IC.Builder.CreateMaxNum(Src0, Src2);
break;
case KnownIEEEMode::Off:
V = ConstSrc1->isNegative() ? IC.Builder.CreateMinimumNum(Src0, Src2)
: IC.Builder.CreateMaximumNum(Src0, Src2);
break;
case KnownIEEEMode::Unknown:
break;
}
} else if (match(Src2, m_APFloat(ConstSrc2)) && ConstSrc2->isInfinity()) {
switch (fpenvIEEEMode(II)) {
case KnownIEEEMode::On:
V = ConstSrc2->isNegative() ? IC.Builder.CreateMinNum(Src0, Src1)
: IC.Builder.CreateMaxNum(Src0, Src1);
break;
case KnownIEEEMode::Off:
V = ConstSrc2->isNegative() ? IC.Builder.CreateMinimumNum(Src0, Src1)
: IC.Builder.CreateMaximumNum(Src0, Src1);
break;
case KnownIEEEMode::Unknown:
break;
}
}

if (V) {
Expand Down
90 changes: 90 additions & 0 deletions llvm/test/Transforms/InstCombine/AMDGPU/fmed3.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -521,6 +521,96 @@ define float @fmed3_neg2_3_snan1_f32(float %x, float %y) #1 {
ret float %med3
}

define float @fmed3_inf_x_y_f32(float %x, float %y) #1 {
; IEEE1-LABEL: define float @fmed3_inf_x_y_f32(
; IEEE1-SAME: float [[X:%.*]], float [[Y:%.*]]) #[[ATTR1]] {
; IEEE1-NEXT: [[MED3:%.*]] = call float @llvm.maxnum.f32(float [[X]], float [[Y]])
; IEEE1-NEXT: ret float [[MED3]]
;
; IEEE0-LABEL: define float @fmed3_inf_x_y_f32(
; IEEE0-SAME: float [[X:%.*]], float [[Y:%.*]]) #[[ATTR1]] {
; IEEE0-NEXT: [[MED3:%.*]] = call float @llvm.maximumnum.f32(float [[X]], float [[Y]])
; IEEE0-NEXT: ret float [[MED3]]
;
%med3 = call float @llvm.amdgcn.fmed3.f32(float 0x7FF0000000000000, float %x, float %y)
ret float %med3
}

define float @fmed3_x_inf_y_f32(float %x, float %y) #1 {
; IEEE1-LABEL: define float @fmed3_x_inf_y_f32(
; IEEE1-SAME: float [[X:%.*]], float [[Y:%.*]]) #[[ATTR1]] {
; IEEE1-NEXT: [[MED3:%.*]] = call float @llvm.maxnum.f32(float [[X]], float [[Y]])
; IEEE1-NEXT: ret float [[MED3]]
;
; IEEE0-LABEL: define float @fmed3_x_inf_y_f32(
; IEEE0-SAME: float [[X:%.*]], float [[Y:%.*]]) #[[ATTR1]] {
; IEEE0-NEXT: [[MED3:%.*]] = call float @llvm.maximumnum.f32(float [[X]], float [[Y]])
; IEEE0-NEXT: ret float [[MED3]]
;
%med3 = call float @llvm.amdgcn.fmed3.f32(float %x, float 0x7FF0000000000000, float %y)
ret float %med3
}

define float @fmed3_x_y_inf_f32(float %x, float %y) #1 {
; IEEE1-LABEL: define float @fmed3_x_y_inf_f32(
; IEEE1-SAME: float [[X:%.*]], float [[Y:%.*]]) #[[ATTR1]] {
; IEEE1-NEXT: [[MED3:%.*]] = call float @llvm.maxnum.f32(float [[X]], float [[Y]])
; IEEE1-NEXT: ret float [[MED3]]
;
; IEEE0-LABEL: define float @fmed3_x_y_inf_f32(
; IEEE0-SAME: float [[X:%.*]], float [[Y:%.*]]) #[[ATTR1]] {
; IEEE0-NEXT: [[MED3:%.*]] = call float @llvm.maximumnum.f32(float [[X]], float [[Y]])
; IEEE0-NEXT: ret float [[MED3]]
;
%med3 = call float @llvm.amdgcn.fmed3.f32(float %x, float %y, float 0x7FF0000000000000)
ret float %med3
}

define float @fmed3_ninf_x_y_f32(float %x, float %y) #1 {
; IEEE1-LABEL: define float @fmed3_ninf_x_y_f32(
; IEEE1-SAME: float [[X:%.*]], float [[Y:%.*]]) #[[ATTR1]] {
; IEEE1-NEXT: [[MED3:%.*]] = call float @llvm.minnum.f32(float [[X]], float [[Y]])
; IEEE1-NEXT: ret float [[MED3]]
;
; IEEE0-LABEL: define float @fmed3_ninf_x_y_f32(
; IEEE0-SAME: float [[X:%.*]], float [[Y:%.*]]) #[[ATTR1]] {
; IEEE0-NEXT: [[MED3:%.*]] = call float @llvm.minimumnum.f32(float [[X]], float [[Y]])
; IEEE0-NEXT: ret float [[MED3]]
;
%med3 = call float @llvm.amdgcn.fmed3.f32(float 0xFFF0000000000000, float %x, float %y)
ret float %med3
}

define float @fmed3_x_ninf_y_f32(float %x, float %y) #1 {
; IEEE1-LABEL: define float @fmed3_x_ninf_y_f32(
; IEEE1-SAME: float [[X:%.*]], float [[Y:%.*]]) #[[ATTR1]] {
; IEEE1-NEXT: [[MED3:%.*]] = call float @llvm.minnum.f32(float [[X]], float [[Y]])
; IEEE1-NEXT: ret float [[MED3]]
;
; IEEE0-LABEL: define float @fmed3_x_ninf_y_f32(
; IEEE0-SAME: float [[X:%.*]], float [[Y:%.*]]) #[[ATTR1]] {
; IEEE0-NEXT: [[MED3:%.*]] = call float @llvm.minimumnum.f32(float [[X]], float [[Y]])
; IEEE0-NEXT: ret float [[MED3]]
;
%med3 = call float @llvm.amdgcn.fmed3.f32(float %x, float 0xFFF0000000000000, float %y)
ret float %med3
}

define float @fmed3_x_y_ninf_f32(float %x, float %y) #1 {
; IEEE1-LABEL: define float @fmed3_x_y_ninf_f32(
; IEEE1-SAME: float [[X:%.*]], float [[Y:%.*]]) #[[ATTR1]] {
; IEEE1-NEXT: [[MED3:%.*]] = call float @llvm.minnum.f32(float [[X]], float [[Y]])
; IEEE1-NEXT: ret float [[MED3]]
;
; IEEE0-LABEL: define float @fmed3_x_y_ninf_f32(
; IEEE0-SAME: float [[X:%.*]], float [[Y:%.*]]) #[[ATTR1]] {
; IEEE0-NEXT: [[MED3:%.*]] = call float @llvm.minimumnum.f32(float [[X]], float [[Y]])
; IEEE0-NEXT: ret float [[MED3]]
;
%med3 = call float @llvm.amdgcn.fmed3.f32(float %x, float %y, float 0xFFF0000000000000)
ret float %med3
}

; --------------------------------------------------------------------
; llvm.amdgcn.fmed3 with default mode implied by shader CC
; --------------------------------------------------------------------
Expand Down
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