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[DemandedBits] Optimize a find()+insert pattern with try_emplace and APInt::operator|= 

llvm-svn: 355284
This commit is contained in:
Fangrui Song 2019-03-03 11:12:57 +00:00
parent 8f04766d13
commit 981f216d1d
1 changed files with 3 additions and 8 deletions
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11
llvm/lib/Analysis/DemandedBits.cpp
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@ -402,14 +402,9 @@ void DemandedBits::performAnalysis() {
// If we've added to the set of alive bits (or the operand has not
// been previously visited), then re-queue the operand to be visited
// again.
APInt ABPrev(BitWidth, 0);
auto ABI = AliveBits.find(I);
if (ABI != AliveBits.end())
ABPrev = ABI->second;
APInt ABNew = AB | ABPrev;
if (ABNew != ABPrev || ABI == AliveBits.end()) {
AliveBits[I] = std::move(ABNew);
auto Res = AliveBits.try_emplace(I);
if (Res.second || (AB |= Res.first->second) != Res.first->second) {
Res.first->second = std::move(AB);
Worklist.insert(I);
}
}