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[InstCombine] Add one-use check when folding fabs over selects #122270

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Merged
dtcxzyw merged 4 commits into from
Jan 29, 2025
Merged

[InstCombine] Add one-use check when folding fabs over selects #122270

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93fa070
[InstCombine] Add pre-commit tests. NFC.
dtcxzyw Jan 9, 2025
b3a5672
[InstCombine] Add one-use check when folding fabs over selects
dtcxzyw Jan 9, 2025
4b87c01
[InstCombine] Add more tests. NFC.
dtcxzyw Jan 9, 2025
5e22ede
[InstCombine] Allow folding with two constant arms
dtcxzyw Jan 9, 2025
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3 changes: 2 additions & 1 deletion llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2709,7 +2709,8 @@ Instruction *InstCombinerImpl::visitCallInst(CallInst &CI) {

if (match(Arg, m_Select(m_Value(Cond), m_Value(TVal), m_Value(FVal)))) {
// fabs (select Cond, TrueC, FalseC) --> select Cond, AbsT, AbsF
if (isa<Constant>(TVal) || isa<Constant>(FVal)) {
if (Arg->hasOneUse() ? (isa<Constant>(TVal) || isa<Constant>(FVal))
: (isa<Constant>(TVal) && isa<Constant>(FVal))) {
CallInst *AbsT = Builder.CreateCall(II->getCalledFunction(), {TVal});
CallInst *AbsF = Builder.CreateCall(II->getCalledFunction(), {FVal});
SelectInst *SI = SelectInst::Create(Cond, AbsT, AbsF);
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27 changes: 27 additions & 0 deletions llvm/test/Transforms/InstCombine/intrinsic-select.ll
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Expand Up @@ -2,6 +2,7 @@
; RUN: opt -passes=instcombine -S < %s | FileCheck %s

declare void @use(i32)
declare void @usef32(float)

declare i32 @llvm.ctlz.i32(i32, i1)
declare <3 x i17> @llvm.ctlz.v3i17(<3 x i17>, i1)
Expand Down Expand Up @@ -344,3 +345,29 @@ define double @test_fabs_select_fmf2(i1 %cond, double %a) {
%fabs = call nnan ninf nsz double @llvm.fabs.f64(double %sel1)
ret double %fabs
}

define float @test_fabs_select_multiuse(i1 %cond, float %x) {
; CHECK-LABEL: @test_fabs_select_multiuse(
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[COND:%.*]], float [[X:%.*]], float 0x7FF0000000000000
; CHECK-NEXT: call void @usef32(float [[SELECT]])
; CHECK-NEXT: [[FABS:%.*]] = call float @llvm.fabs.f32(float [[SELECT]])
; CHECK-NEXT: ret float [[FABS]]
;
%select = select i1 %cond, float %x, float 0x7FF0000000000000
call void @usef32(float %select)
%fabs = call float @llvm.fabs.f32(float %select)
ret float %fabs
}

define float @test_fabs_select_multiuse_both_constant(i1 %cond, float %x) {
; CHECK-LABEL: @test_fabs_select_multiuse_both_constant(
; CHECK-NEXT: [[SELECT:%.*]] = select i1 [[COND:%.*]], float -1.000000e+00, float -2.000000e+00
; CHECK-NEXT: call void @usef32(float [[SELECT]])
; CHECK-NEXT: [[FABS:%.*]] = select i1 [[COND]], float 1.000000e+00, float 2.000000e+00
; CHECK-NEXT: ret float [[FABS]]
;
%select = select i1 %cond, float -1.0, float -2.0
call void @usef32(float %select)
%fabs = call float @llvm.fabs.f32(float %select)
ret float %fabs
}
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