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Fix PR2553 

llvm-svn: 53715
This commit is contained in:
Chris Lattner 2008-07-17 06:07:20 +00:00
parent 1e2c6bfa41
commit c600c53d1f
2 changed files with 10 additions and 1 deletions
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3
llvm/lib/Transforms/Scalar/InstructionCombining.cpp
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@ -2255,7 +2255,8 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
Instruction *InstCombiner::visitSub(BinaryOperator &I) { Instruction *InstCombiner::visitSub(BinaryOperator &I) {
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1); Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
if (Op0 == Op1) // sub X, X -> 0 if (Op0 == Op1 && // sub X, X -> 0
!I.getType()->isFPOrFPVector())
return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
// If this is a 'B = x-(-A)', change to B = x+A... // If this is a 'B = x-(-A)', change to B = x+A...

8
llvm/test/Transforms/InstCombine/2008-07-16-fsub.ll Normal file
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@ -0,0 +1,8 @@
; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep sub
; PR2553
define double @test(double %X) nounwind {
; fsub of self can't be optimized away.
%Y = sub double %X, %X
ret double %Y
}