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PR9450: Make switch optimization in SimplifyCFG not dependent on the ordering

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of pointers in an std::map.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127650 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eli Friedman
2011-03-15 02:23:35 +00:00
parent bf34a5ec22
commit b1a6eab655
2 changed files with 66 additions and 15 deletions
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25
lib/Transforms/Utils/SimplifyCFG.cpp
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@ -2211,17 +2211,28 @@ bool SimplifyCFGOpt::SimplifyUnreachable(UnreachableInst *UI) {
// If the default value is unreachable, figure out the most popular
// destination and make it the default.
if (SI->getSuccessor(0) == BB) {
std::map<BasicBlock*, unsigned> Popularity;
for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i)
Popularity[SI->getSuccessor(i)]++;
std::map<BasicBlock*, std::pair<unsigned, unsigned> > Popularity;
for (unsigned i = 1, e = SI->getNumCases(); i != e; ++i) {
std::pair<unsigned, unsigned>& entry =
Popularity[SI->getSuccessor(i)];
if (entry.first == 0) {
entry.first = 1;
entry.second = i;
} else {
entry.first++;
}
}
// Find the most popular block.
unsigned MaxPop = 0;
unsigned MaxIndex = 0;
BasicBlock *MaxBlock = 0;
for (std::map<BasicBlock*, unsigned>::iterator
for (std::map<BasicBlock*, std::pair<unsigned, unsigned> >::iterator
I = Popularity.begin(), E = Popularity.end(); I != E; ++I) {
if (I->second > MaxPop) {
MaxPop = I->second;
if (I->second.first > MaxPop ||
(I->second.first == MaxPop && MaxIndex > I->second.second)) {
MaxPop = I->second.first;
MaxIndex = I->second.second;
MaxBlock = I->first;
}
}