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[InstCombine] Add a peephole for redundant assumes 

Two or more identical assumes are occasionally next to each other in a
basic block.
While our generic machinery will turn a redundant assume into a no-op,
it is not super cheap.
We can perform a simpler check to achieve the same result for this case.

llvm-svn: 265801
This commit is contained in:
David Majnemer 2016-04-08 16:37:12 +00:00
parent 60c6abc3cc
commit fcc5811797
1 changed files with 7 additions and 2 deletions
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9
llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
View File

@ -1943,11 +1943,16 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
break;
}
case Intrinsic::assume: {
Value *IIOperand = II->getArgOperand(0);
// Remove an assume if it is immediately followed by an identical assume.
if (match(II->getNextNode(),
m_Intrinsic<Intrinsic::assume>(m_Specific(IIOperand))))
return eraseInstFromFunction(CI);
// Canonicalize assume(a && b) -> assume(a); assume(b);
// Note: New assumption intrinsics created here are registered by
// the InstCombineIRInserter object.
Value *IIOperand = II->getArgOperand(0), *A, *B,
*AssumeIntrinsic = II->getCalledValue();
Value *AssumeIntrinsic = II->getCalledValue(), *A, *B;
if (match(IIOperand, m_And(m_Value(A), m_Value(B)))) {
Builder->CreateCall(AssumeIntrinsic, A, II->getName());
Builder->CreateCall(AssumeIntrinsic, B, II->getName());