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[InstCombine] x /c fabs(x) -> copysign(1.0, x) 

Summary:
x / fabs(x) -> copysign(1.0, x)
fabs(x) / x -> copysign(1.0, x)

Reviewers: spatel, foad, RKSimon, efriedma

Reviewed By: spatel

Subscribers: lebedev.ri, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D65898

llvm-svn: 368570
This commit is contained in:
David Bolvansky 2019-08-12 13:43:35 +00:00
parent 020eea0c16
commit 20d37fab82
2 changed files with 39 additions and 11 deletions
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11
llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
View File

@ -1234,6 +1234,17 @@ Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
return &I;
}
// X / fabs(X) -> copysign(1.0, X)
// fabs(X) / X -> copysign(1.0, X)
if (I.hasNoNaNs() && I.hasNoInfs() &&
(match(&I,
m_FDiv(m_Value(X), m_Intrinsic<Intrinsic::fabs>(m_Deferred(X)))) ||
match(&I, m_FDiv(m_Intrinsic<Intrinsic::fabs>(m_Value(X)),
m_Deferred(X))))) {
Value *V = Builder.CreateBinaryIntrinsic(
Intrinsic::copysign, ConstantFP::get(I.getType(), 1.0), X, &I);
return replaceInstUsesWith(I, V);
}
return nullptr;
}

39
llvm/test/Transforms/InstCombine/fabs-copysign.ll
View File

@ -3,6 +3,7 @@
declare double @llvm.fabs.f64(double)
declare float @llvm.fabs.f32(float)
declare <4 x double> @llvm.fabs.v4f64(<4 x double>)
declare void @use(double)
declare double @llvm.copysign.f64(double, double)
@ -10,9 +11,8 @@ declare float @llvm.copysign.f32(float, float)
define double @fabs_copysign(double %x) {
; CHECK-LABEL: @fabs_copysign(
; CHECK-NEXT: [[F:%.*]] = tail call double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: [[DIV:%.*]] = fdiv nnan ninf double [[X]], [[F]]
; CHECK-NEXT: ret double [[DIV]]
; CHECK-NEXT: [[TMP1:%.*]] = call nnan ninf double @llvm.copysign.f64(double 1.000000e+00, double [[X:%.*]])
; CHECK-NEXT: ret double [[TMP1]]
;
%f = tail call double @llvm.fabs.f64(double %x)
%div = fdiv nnan ninf double %x, %f
@ -21,21 +21,38 @@ define double @fabs_copysign(double %x) {
define double @fabs_copysign_commuted(double %x) {
; CHECK-LABEL: @fabs_copysign_commuted(
; CHECK-NEXT: [[F:%.*]] = tail call double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: [[DIV:%.*]] = fdiv nnan ninf double [[F]], [[X]]
; CHECK-NEXT: ret double [[DIV]]
; CHECK-NEXT: [[TMP1:%.*]] = call nnan ninf double @llvm.copysign.f64(double 1.000000e+00, double [[X:%.*]])
; CHECK-NEXT: ret double [[TMP1]]
;
%f = tail call double @llvm.fabs.f64(double %x)
%div = fdiv nnan ninf double %f, %x
ret double %div
}
define <4 x double> @fabs_copysign_vec(<4 x double> %x) {
; CHECK-LABEL: @fabs_copysign_vec(
; CHECK-NEXT: [[TMP1:%.*]] = call nnan ninf <4 x double> @llvm.copysign.v4f64(<4 x double> <double 1.000000e+00, double 1.000000e+00, double 1.000000e+00, double 1.000000e+00>, <4 x double> [[X:%.*]])
; CHECK-NEXT: ret <4 x double> [[TMP1]]
;
%f = call <4 x double> @llvm.fabs.v4f64(<4 x double> %x)
%div = fdiv nnan ninf <4 x double> %x, %f
ret <4 x double> %div
}
define <4 x double> @fabs_copysign_vec_commuted(<4 x double> %x) {
; CHECK-LABEL: @fabs_copysign_vec_commuted(
; CHECK-NEXT: [[TMP1:%.*]] = call nnan ninf <4 x double> @llvm.copysign.v4f64(<4 x double> <double 1.000000e+00, double 1.000000e+00, double 1.000000e+00, double 1.000000e+00>, <4 x double> [[X:%.*]])
; CHECK-NEXT: ret <4 x double> [[TMP1]]
;
%f = call <4 x double> @llvm.fabs.v4f64(<4 x double> %x)
%div = fdiv nnan ninf <4 x double> %f, %x
ret <4 x double> %div
}
define float @fabs_copysignf(float %x) {
; CHECK-LABEL: @fabs_copysignf(
; CHECK-NEXT: [[F:%.*]] = tail call float @llvm.fabs.f32(float [[X:%.*]])
; CHECK-NEXT: [[DIV:%.*]] = fdiv nnan ninf float [[X]], [[F]]
; CHECK-NEXT: ret float [[DIV]]
; CHECK-NEXT: [[TMP1:%.*]] = call nnan ninf float @llvm.copysign.f32(float 1.000000e+00, float [[X:%.*]])
; CHECK-NEXT: ret float [[TMP1]]
;
%f = tail call float @llvm.fabs.f32(float %x)
%div = fdiv nnan ninf float %x, %f
@ -46,8 +63,8 @@ define double @fabs_copysign_use(double %x) {
; CHECK-LABEL: @fabs_copysign_use(
; CHECK-NEXT: [[F:%.*]] = tail call double @llvm.fabs.f64(double [[X:%.*]])
; CHECK-NEXT: call void @use(double [[F]])
; CHECK-NEXT: [[DIV:%.*]] = fdiv nnan ninf double [[X]], [[F]]
; CHECK-NEXT: ret double [[DIV]]
; CHECK-NEXT: [[TMP1:%.*]] = call nnan ninf double @llvm.copysign.f64(double 1.000000e+00, double [[X]])
; CHECK-NEXT: ret double [[TMP1]]
;
%f = tail call double @llvm.fabs.f64(double %x)
call void @use(double %f)