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[InstSimplify] Restore fsub 0.0, (fsub 0.0, X) ==> X optzn

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I accidentally removed this in r262212 but there was no test coverage to
detect it.

llvm-svn: 262215
This commit is contained in:
Benjamin Kramer 2016-02-29 12:18:25 +00:00
parent 76d76bb006
commit 6bb15021b3
2 changed files with 11 additions and 1 deletions
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2
llvm/lib/Analysis/InstructionSimplify.cpp
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@ -839,7 +839,7 @@ static Value *SimplifyFSubInst(Value *Op0, Value *Op1, FastMathFlags FMF,
return X;
// fsub 0.0, (fsub 0.0, X) ==> X if signed zeros are ignored.
if (FMF.noSignedZeros() && match(Op0, m_NegZero()) &&
if (FMF.noSignedZeros() && match(Op0, m_AnyZero()) &&
match(Op1, m_FSub(m_AnyZero(), m_Value(X))))
return X;

10
llvm/test/Transforms/InstSimplify/fast-math.ll
View File

@ -91,6 +91,16 @@ define float @fsub_x_x(float %a) {
ret float %ret
}
; fsub nsz 0.0, (fsub 0.0, X) ==> X
; CHECK-LABEL: @fsub_0_0_x(
define float @fsub_0_0_x(float %a) {
%t1 = fsub float 0.0, %a
%ret = fsub nsz float 0.0, %t1
; CHECK: ret float %a
ret float %ret
}
; fadd nsz X, 0 ==> X
; CHECK-LABEL: @nofold_fadd_x_0(
define float @nofold_fadd_x_0(float %a) {