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use IC.ReplaceInstUsesWith instead of a raw RAUW so that uses of

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the old thing end up on the instcombine worklist.  Not doing this
can cause an extra top-level iteration of instcombine, burning
compile time.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122179 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2010-12-19 18:38:44 +00:00
parent 0a62474830
commit 0fe80bbbb6
1 changed files with 5 additions and 3 deletions
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8
lib/Transforms/InstCombine/InstCombineCompares.cpp
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@ -1592,7 +1592,7 @@ Instruction *InstCombiner::visitICmpInstWithCastAndCast(ICmpInst &ICI) {
///
static Instruction *ProcessUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B,
ConstantInt *CI2, ConstantInt *CI1,
InstCombiner::BuilderTy *Builder) {
InstCombiner &IC) {
// The transformation we're trying to do here is to transform this into an
// llvm.sadd.with.overflow. To do this, we have to replace the original add
// with a narrower add, and discard the add-with-constant that is part of the
@ -1644,6 +1644,8 @@ static Instruction *ProcessUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B,
Value *F = Intrinsic::getDeclaration(M, Intrinsic::sadd_with_overflow,
&NewType, 1);
InstCombiner::BuilderTy *Builder = IC.Builder;
// Put the new code above the original add, in case there are any uses of the
// add between the add and the compare.
Builder->SetInsertPoint(OrigAdd->getParent(), BasicBlock::iterator(OrigAdd));
@ -1656,7 +1658,7 @@ static Instruction *ProcessUGT_ADDCST_ADD(ICmpInst &I, Value *A, Value *B,
// The inner add was the result of the narrow add, zero extended to the
// wider type. Replace it with the result computed by the intrinsic.
OrigAdd->replaceAllUsesWith(ZExt);
IC.ReplaceInstUsesWith(*OrigAdd, ZExt);
// The original icmp gets replaced with the overflow value.
return ExtractValueInst::Create(Call, 1, "sadd.overflow");
@ -1751,7 +1753,7 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) {
ConstantInt *CI2; // I = icmp ugt (add (add A, B), CI2), CI
if (I.getPredicate() == ICmpInst::ICMP_UGT &&
match(Op0, m_Add(m_Add(m_Value(A), m_Value(B)), m_ConstantInt(CI2))))
if (Instruction *Res = ProcessUGT_ADDCST_ADD(I, A, B, CI2, CI, Builder))
if (Instruction *Res = ProcessUGT_ADDCST_ADD(I, A, B, CI2, CI, *this))
return Res;
}