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APFloat: Fix signed zero handling in minnum/maxnum #83376

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Merged
merged 4 commits into from
Feb 29, 2024
Merged

APFloat: Fix signed zero handling in minnum/maxnum #83376

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29f6732
APFloat: Fix signed zero handling in minnum/maxnum
arsenm Feb 29, 2024
6031db5
Merge branch 'main' into apfloat-signed-zero-min-max
arsenm Feb 29, 2024
dfb5552
Update IEEE spec reference
arsenm Feb 29, 2024
68300dd
Complete signed zero documentation
arsenm Feb 29, 2024
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4 changes: 4 additions & 0 deletions llvm/include/llvm/ADT/APFloat.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1397,6 +1397,8 @@ inline APFloat minnum(const APFloat &A, const APFloat &B) {
return B;
if (B.isNaN())
return A;
if (A.isZero() && B.isZero() && (A.isNegative() != B.isNegative()))
return A.isNegative() ? A : B;
return B < A ? B : A;
}

Expand All @@ -1408,6 +1410,8 @@ inline APFloat maxnum(const APFloat &A, const APFloat &B) {
return B;
if (B.isNaN())
return A;
if (A.isZero() && B.isZero() && (A.isNegative() != B.isNegative()))
return A.isNegative() ? B : A;
return A < B ? B : A;
}

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2 changes: 1 addition & 1 deletion llvm/test/CodeGen/AMDGPU/fmaxnum.ll
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Expand Up @@ -152,7 +152,7 @@ define amdgpu_kernel void @constant_fold_fmax_f32_p0_n0(ptr addrspace(1) %out) #

; GCN-LABEL: {{^}}constant_fold_fmax_f32_n0_p0:
; GCN-NOT: v_max_f32_e32
; GCN: v_bfrev_b32_e32 [[REG:v[0-9]+]], 1{{$}}
; GCN: v_mov_b32_e32 [[REG:v[0-9]+]], 0{{$}}
; GCN: buffer_store_dword [[REG]]
define amdgpu_kernel void @constant_fold_fmax_f32_n0_p0(ptr addrspace(1) %out) #0 {
%val = call float @llvm.maxnum.f32(float -0.0, float 0.0)
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/CodeGen/AMDGPU/fminnum.ll
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Expand Up @@ -150,7 +150,7 @@ define amdgpu_kernel void @constant_fold_fmin_f32_p0_p0(ptr addrspace(1) %out) #

; GCN-LABEL: {{^}}constant_fold_fmin_f32_p0_n0:
; GCN-NOT: v_min_f32_e32
; GCN: v_mov_b32_e32 [[REG:v[0-9]+]], 0
; GCN: v_bfrev_b32_e32 [[REG:v[0-9]+]], 1{{$}}
; GCN: buffer_store_dword [[REG]]
define amdgpu_kernel void @constant_fold_fmin_f32_p0_n0(ptr addrspace(1) %out) #0 {
%val = call float @llvm.minnum.f32(float 0.0, float -0.0)
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/Transforms/InstCombine/maxnum.ll
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Expand Up @@ -66,7 +66,7 @@ define float @constant_fold_maxnum_f32_p0_n0() {

define float @constant_fold_maxnum_f32_n0_p0() {
; CHECK-LABEL: @constant_fold_maxnum_f32_n0_p0(
; CHECK-NEXT: ret float -0.000000e+00
; CHECK-NEXT: ret float 0.000000e+00
;
%x = call float @llvm.maxnum.f32(float -0.0, float 0.0)
ret float %x
Expand Down
4 changes: 2 additions & 2 deletions llvm/test/Transforms/InstCombine/minnum.ll
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Expand Up @@ -60,7 +60,7 @@ define float @constant_fold_minnum_f32_p0_p0() {

define float @constant_fold_minnum_f32_p0_n0() {
; CHECK-LABEL: @constant_fold_minnum_f32_p0_n0(
; CHECK-NEXT: ret float 0.000000e+00
; CHECK-NEXT: ret float -0.000000e+00
;
%x = call float @llvm.minnum.f32(float 0.0, float -0.0)
ret float %x
Expand Down Expand Up @@ -199,7 +199,7 @@ define float @minnum_f32_1_minnum_p0_val_fmf3(float %x) {

define float @minnum_f32_p0_minnum_val_n0(float %x) {
; CHECK-LABEL: @minnum_f32_p0_minnum_val_n0(
; CHECK-NEXT: [[Z:%.*]] = call float @llvm.minnum.f32(float [[X:%.*]], float 0.000000e+00)
; CHECK-NEXT: [[Z:%.*]] = call float @llvm.minnum.f32(float [[X:%.*]], float -0.000000e+00)
; CHECK-NEXT: ret float [[Z]]
;
%y = call float @llvm.minnum.f32(float %x, float -0.0)
Expand Down
68 changes: 66 additions & 2 deletions llvm/test/Transforms/InstSimplify/ConstProp/min-max.ll
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Expand Up @@ -49,6 +49,38 @@ define float @minnum_float() {
ret float %1
}

define float @minnum_float_p0_n0() {
; CHECK-LABEL: @minnum_float_p0_n0(
; CHECK-NEXT: ret float -0.000000e+00
;
%min = call float @llvm.minnum.f32(float 0.0, float -0.0)
ret float %min
}

define float @minnum_float_n0_p0() {
; CHECK-LABEL: @minnum_float_n0_p0(
; CHECK-NEXT: ret float -0.000000e+00
;
%min = call float @llvm.minnum.f32(float -0.0, float 0.0)
ret float %min
}

define float @minnum_float_p0_qnan() {
; CHECK-LABEL: @minnum_float_p0_qnan(
; CHECK-NEXT: ret float 0.000000e+00
;
%min = call float @llvm.minnum.f32(float 0.0, float 0x7FF8000000000000)
ret float %min
}

define float @minnum_float_qnan_p0() {
; CHECK-LABEL: @minnum_float_qnan_p0(
; CHECK-NEXT: ret float 0.000000e+00
;
%min = call float @llvm.minnum.f32(float 0x7FF8000000000000, float 0.0)
ret float %min
}

define bfloat @minnum_bfloat() {
; CHECK-LABEL: @minnum_bfloat(
; CHECK-NEXT: ret bfloat 0xR40A0
Expand Down Expand Up @@ -95,7 +127,7 @@ define <4 x half> @minnum_half_vec() {

define <4 x float> @minnum_float_zeros_vec() {
; CHECK-LABEL: @minnum_float_zeros_vec(
; CHECK-NEXT: ret <4 x float> <float 0.000000e+00, float -0.000000e+00, float 0.000000e+00, float -0.000000e+00>
; CHECK-NEXT: ret <4 x float> <float 0.000000e+00, float -0.000000e+00, float -0.000000e+00, float -0.000000e+00>
;
%1 = call <4 x float> @llvm.minnum.v4f32(<4 x float> <float 0.0, float -0.0, float 0.0, float -0.0>, <4 x float> <float 0.0, float 0.0, float -0.0, float -0.0>)
ret <4 x float> %1
Expand All @@ -109,6 +141,38 @@ define float @maxnum_float() {
ret float %1
}

define float @maxnum_float_p0_n0() {
; CHECK-LABEL: @maxnum_float_p0_n0(
; CHECK-NEXT: ret float 0.000000e+00
;
%max = call float @llvm.maxnum.f32(float 0.0, float -0.0)
ret float %max
}

define float @maxnum_float_n0_p0() {
; CHECK-LABEL: @maxnum_float_n0_p0(
; CHECK-NEXT: ret float 0.000000e+00
;
%max = call float @llvm.maxnum.f32(float -0.0, float 0.0)
ret float %max
}

define float @maxnum_float_p0_qnan() {
; CHECK-LABEL: @maxnum_float_p0_qnan(
; CHECK-NEXT: ret float 0.000000e+00
;
%max = call float @llvm.maxnum.f32(float 0.0, float 0x7FF8000000000000)
ret float %max
}

define float @maxnum_float_qnan_p0() {
; CHECK-LABEL: @maxnum_float_qnan_p0(
; CHECK-NEXT: ret float 0.000000e+00
;
%max = call float @llvm.maxnum.f32(float 0x7FF8000000000000, float 0.0)
ret float %max
}

define bfloat @maxnum_bfloat() {
; CHECK-LABEL: @maxnum_bfloat(
; CHECK-NEXT: ret bfloat 0xR4228
Expand Down Expand Up @@ -155,7 +219,7 @@ define <4 x half> @maxnum_half_vec() {

define <4 x float> @maxnum_float_zeros_vec() {
; CHECK-LABEL: @maxnum_float_zeros_vec(
; CHECK-NEXT: ret <4 x float> <float 0.000000e+00, float -0.000000e+00, float 0.000000e+00, float -0.000000e+00>
; CHECK-NEXT: ret <4 x float> <float 0.000000e+00, float 0.000000e+00, float 0.000000e+00, float -0.000000e+00>
;
%1 = call <4 x float> @llvm.maxnum.v4f32(<4 x float> <float 0.0, float -0.0, float 0.0, float -0.0>, <4 x float> <float 0.0, float 0.0, float -0.0, float -0.0>)
ret <4 x float> %1
Expand Down
10 changes: 10 additions & 0 deletions llvm/unittests/ADT/APFloatTest.cpp
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Expand Up @@ -578,6 +578,11 @@ TEST(APFloatTest, MinNum) {
EXPECT_EQ(1.0, minnum(f2, f1).convertToDouble());
EXPECT_EQ(1.0, minnum(f1, nan).convertToDouble());
EXPECT_EQ(1.0, minnum(nan, f1).convertToDouble());

APFloat zp(0.0);
APFloat zn(-0.0);
EXPECT_EQ(-0.0, minnum(zp, zn).convertToDouble());
EXPECT_EQ(-0.0, minnum(zn, zp).convertToDouble());
}

TEST(APFloatTest, MaxNum) {
Expand All @@ -589,6 +594,11 @@ TEST(APFloatTest, MaxNum) {
EXPECT_EQ(2.0, maxnum(f2, f1).convertToDouble());
EXPECT_EQ(1.0, maxnum(f1, nan).convertToDouble());
EXPECT_EQ(1.0, maxnum(nan, f1).convertToDouble());

APFloat zp(0.0);
APFloat zn(-0.0);
EXPECT_EQ(0.0, maxnum(zp, zn).convertToDouble());
EXPECT_EQ(0.0, maxnum(zn, zp).convertToDouble());
}

TEST(APFloatTest, Minimum) {
Expand Down