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InstCombine: Turn mul.with.overflow(X, 2) into the cheaper add.with.overflow(X, X)

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131789 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Benjamin Kramer
2011-05-21 09:22:06 +00:00
parent 37fed38ec1
commit c21b205f93
2 changed files with 35 additions and 0 deletions
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14
lib/Transforms/InstCombine/InstCombineCalls.cpp
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@@ -535,6 +535,20 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
Constant *Struct = ConstantStruct::get(II->getContext(), V, 2, false);
return InsertValueInst::Create(Struct, II->getArgOperand(0), 0);
}
// [su]mul.with.overflow(X, 2) -> [su]add.with.overflow(X, X)
if (RHSI->equalsInt(2)) {
Intrinsic::ID Add =
II->getIntrinsicID() == Intrinsic::smul_with_overflow ?
Intrinsic::sadd_with_overflow : Intrinsic::uadd_with_overflow;
Module *M = II->getParent()->getParent()->getParent();
const Type *Ty = RHSI->getType();
Function *F = Intrinsic::getDeclaration(M, Add, &Ty, 1);
Value *Ops[] = { II->getArgOperand(0), II->getArgOperand(0) };
return CallInst::Create(F, Ops, Ops+2);
}
}
break;
case Intrinsic::ppc_altivec_lvx: