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Fix misoptimization of: xor i1 (icmp eq (X, C1), icmp s[lg]t (X, C2)) 

llvm-svn: 56834
This commit is contained in:
Nick Lewycky 2008-09-30 06:08:34 +00:00
parent a930b56252
commit e8ced3ec19
2 changed files with 13 additions and 2 deletions
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5
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
View File

@ -3023,7 +3023,7 @@ Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
I.setOperand(1, RHSNeg);
return &I;
}
// If the sign bits of both operands are zero (i.e. we can prove they are
// unsigned inputs), turn this into a urem.
if (I.getType()->isInteger()) {
@ -4205,7 +4205,8 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
// Ensure that the larger constant is on the RHS.
ICmpInst *LHS = cast<ICmpInst>(Op0);
bool NeedsSwap;
if (ICmpInst::isSignedPredicate(LHSCC))
if (ICmpInst::isEquality(LHSCC) ? ICmpInst::isSignedPredicate(RHSCC)
: ICmpInst::isSignedPredicate(LHSCC))
NeedsSwap = LHSCst->getValue().sgt(RHSCst->getValue());
else
NeedsSwap = LHSCst->getValue().ugt(RHSCst->getValue());

10
llvm/test/Transforms/InstCombine/2008-09-29-FoldingOr.ll Normal file
View File

@ -0,0 +1,10 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep {or i1}
; PR2844
define i32 @test(i32 %p_74) {
%A = icmp eq i32 %p_74, 0 ; <i1> [#uses=1]
%B = icmp slt i32 %p_74, -638208501 ; <i1> [#uses=1]
%or.cond = or i1 %A, %B ; <i1> [#uses=1]
%iftmp.10.0 = select i1 %or.cond, i32 0, i32 1 ; <i32> [#uses=1]
ret i32 %iftmp.10.0
}