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Restore minor deletion.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@70892 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Mike Stump
2009-05-04 18:40:41 +00:00
parent 04fa35ab13
commit fe095f39e7
24 changed files with 369 additions and 223 deletions
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50
lib/Transforms/Utils/BasicBlockUtils.cpp
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@@ -442,6 +442,56 @@ BasicBlock *llvm::SplitBlockPredecessors(BasicBlock *BB,
return NewBB;
}
/// FindFunctionBackedges - Analyze the specified function to find all of the
/// loop backedges in the function and return them. This is a relatively cheap
/// (compared to computing dominators and loop info) analysis.
///
/// The output is added to Result, as pairs of <from,to> edge info.
void llvm::FindFunctionBackedges(const Function &F,
SmallVectorImpl<std::pair<const BasicBlock*,const BasicBlock*> > &Result) {
const BasicBlock *BB = &F.getEntryBlock();
if (succ_begin(BB) == succ_end(BB))
return;
SmallPtrSet<const BasicBlock*, 8> Visited;
SmallVector<std::pair<const BasicBlock*, succ_const_iterator>, 8> VisitStack;
SmallPtrSet<const BasicBlock*, 8> InStack;
Visited.insert(BB);
VisitStack.push_back(std::make_pair(BB, succ_begin(BB)));
InStack.insert(BB);
do {
std::pair<const BasicBlock*, succ_const_iterator> &Top = VisitStack.back();
const BasicBlock *ParentBB = Top.first;
succ_const_iterator &I = Top.second;
bool FoundNew = false;
while (I != succ_end(ParentBB)) {
BB = *I++;
if (Visited.insert(BB)) {
FoundNew = true;
break;
}
// Successor is in VisitStack, it's a back edge.
if (InStack.count(BB))
Result.push_back(std::make_pair(ParentBB, BB));
}
if (FoundNew) {
// Go down one level if there is a unvisited successor.
InStack.insert(BB);
VisitStack.push_back(std::make_pair(BB, succ_begin(BB)));
} else {
// Go up one level.
InStack.erase(VisitStack.pop_back_val().first);
}
} while (!VisitStack.empty());
}
/// AreEquivalentAddressValues - Test if A and B will obviously have the same
/// value. This includes recognizing that %t0 and %t1 will have the same
/// value in code like this: