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It's safe to fold not of fcmp.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40870 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky 2007-08-06 20:04:16 +00:00
parent 450770de65
commit f947b3edb5
2 changed files with 18 additions and 3 deletions
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11
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -4134,12 +4134,17 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
// xor (icmp A, B), true = not (icmp A, B) = !icmp A, B
if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
if (RHS == ConstantInt::getTrue() && ICI->hasOneUse())
// xor (cmp A, B), true = not (cmp A, B) = !cmp A, B
if (RHS == ConstantInt::getTrue() && Op0->hasOneUse()) {
if (ICmpInst *ICI = dyn_cast<ICmpInst>(Op0))
return new ICmpInst(ICI->getInversePredicate(),
ICI->getOperand(0), ICI->getOperand(1));
if (FCmpInst *FCI = dyn_cast<FCmpInst>(Op0))
return new FCmpInst(FCI->getInversePredicate(),
FCI->getOperand(0), FCI->getOperand(1));
}
if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
// ~(c-X) == X-c-1 == X+(-c-1)
if (Op0I->getOpcode() == Instruction::Sub && RHS->isAllOnesValue())

10
test/Transforms/InstCombine/not-fcmp.ll Normal file
View File

@ -0,0 +1,10 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep "fcmp uge"
; PR1570
define i1 @f(float %X, float %Y) {
entry:
%tmp3 = fcmp olt float %X, %Y ; <i1> [#uses=1]
%toBoolnot5 = xor i1 %tmp3, true ; <i1> [#uses=1]
ret i1 %toBoolnot5
}