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Revert "[SelectionDAG] Remove unused FP constant in getNegatedExpression"

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2508ef01 doesn't totally fix the issue since we did not handle the case
when unused temporary negated result is the same with the result, which
is found by address sanitizer.

(cherry picked from commit e1669843f2aaf1e4929afdd8f125c14536d27664)
This commit is contained in:
Qiu Chaofan 2020-09-15 22:03:50 +08:00 committed by Hans Wennborg
parent d3f2114698
commit 4daf36af28
2 changed files with 1 additions and 31 deletions
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4
lib/CodeGen/SelectionDAG/TargetLowering.cpp
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@ -5751,10 +5751,8 @@ SDValue TargetLowering::getNegatedExpression(SDValue Op, SelectionDAG &DAG,
// If we already have the use of the negated floating constant, it is free
// to negate it even it has multiple uses.
if (!Op.hasOneUse() && CFP.use_empty()) {
RemoveDeadNode(CFP);
if (!Op.hasOneUse() && CFP.use_empty())
break;
}
Cost = NegatibleCost::Neutral;
return CFP;
}

28
test/CodeGen/X86/pr47517.ll
View File

@ -1,28 +0,0 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -mtriple x86_64 < %s | FileCheck %s
; To ensure unused floating point constant is removed in negation
define float @test(float %src, float* %p) {
; CHECK-LABEL: test:
; CHECK: # %bb.0: # %entry
; CHECK-NEXT: movq $0, (%rdi)
; CHECK-NEXT: xorps %xmm0, %xmm0
; CHECK-NEXT: retq
entry:
%a0 = getelementptr inbounds float, float* %p, i32 0
%a1 = getelementptr inbounds float, float* %p, i32 1
store float 0.000000e+00, float* %a0
store float 0.000000e+00, float* %a1
%zero = load float, float* %a0
%fmul1 = fmul fast float %zero, %src
%fadd1 = fadd fast float %fmul1, %zero
%fmul2 = fmul fast float %fadd1, 2.000000e+00
%fmul3 = fmul fast float %fmul2, %fmul2
%fmul4 = fmul fast float %fmul2, 2.000000e+00
%fadd2 = fadd fast float %fmul4, -3.000000e+00
%fmul5 = fmul fast float %fadd2, %fmul2
%fadd3 = fadd fast float %fmul2, %src
%fadd4 = fadd fast float %fadd3, %fmul5
%fmul6 = fmul fast float %fmul3, %fadd4
ret float %fmul6
}