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Preserve fast-math flags when folding (fsub x, (fneg y)) to (fadd x, y).

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187462 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Owen Anderson 2013-07-30 23:53:17 +00:00
parent b0bee810e7
commit 605b3427a9
2 changed files with 22 additions and 4 deletions
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15
lib/Transforms/InstCombine/InstCombineAddSub.cpp
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@ -1530,17 +1530,24 @@ Instruction *InstCombiner::visitFSub(BinaryOperator &I) {
// If this is a 'B = x-(-A)', change to B = x+A, potentially looking
// through FP extensions/truncations along the way.
if (Value *V = dyn_castFNegVal(Op1))
return BinaryOperator::CreateFAdd(Op0, V);
if (Value *V = dyn_castFNegVal(Op1)) {
Instruction *NewI = BinaryOperator::CreateFAdd(Op0, V);
NewI->copyFastMathFlags(&I);
return NewI;
}
if (FPTruncInst *FPTI = dyn_cast<FPTruncInst>(Op1)) {
if (Value *V = dyn_castFNegVal(FPTI->getOperand(0))) {
Value *NewTrunc = Builder->CreateFPTrunc(V, I.getType());
return BinaryOperator::CreateFAdd(Op0, NewTrunc);
Instruction *NewI = BinaryOperator::CreateFAdd(Op0, NewTrunc);
NewI->copyFastMathFlags(&I);
return NewI;
}
} else if (FPExtInst *FPEI = dyn_cast<FPExtInst>(Op1)) {
if (Value *V = dyn_castFNegVal(FPEI->getOperand(0))) {
Value *NewExt = Builder->CreateFPExt(V, I.getType());
return BinaryOperator::CreateFAdd(Op0, NewExt);
Instruction *NewI = BinaryOperator::CreateFAdd(Op0, NewExt);
NewI->copyFastMathFlags(&I);
return NewI;
}
}

11
test/Transforms/InstCombine/fneg-ext.ll
View File

@ -10,3 +10,14 @@ define double @test1(float %a, double %b) nounwind readnone ssp uwtable {
%3 = fsub double %b, %2
ret double %3
}
; CHECK: test2
define double @test2(float %a, double %b) nounwind readnone ssp uwtable {
; CHECK-NOT: fsub
; CHECK: fpext
; CHECK: fadd fast
%1 = fsub float -0.000000e+00, %a
%2 = fpext float %1 to double
%3 = fsub fast double %b, %2
ret double %3
}