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Make Loop::getExitBlocks significantly faster for large loops. Instead of

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pounding on Loop::contains (which is O(n) in the size of the loop), use a
sorted vector, which is O(log(N)) for each query.  This speeds up Duraid's
horrible testcase from ~72s to ~31s in a debug build.

llvm-svn: 29645
This commit is contained in:
Chris Lattner 2006-08-12 05:02:03 +00:00
parent 0885025198
commit 9781d44b6e
1 changed files with 9 additions and 3 deletions
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12
lib/Analysis/LoopInfo.cpp
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@ -336,11 +336,17 @@ void LoopInfo::removeBlock(BasicBlock *BB) {
/// are the blocks _outside of the current loop_ which are branched to.
///
void Loop::getExitBlocks(std::vector<BasicBlock*> &ExitBlocks) const {
// Sort the blocks vector so that we can use binary search to do quick
// lookups.
std::vector<BasicBlock*> LoopBBs(block_begin(), block_end());
std::sort(LoopBBs.begin(), LoopBBs.end());
for (std::vector<BasicBlock*>::const_iterator BI = Blocks.begin(),
BE = Blocks.end(); BI != BE; ++BI)
BE = Blocks.end(); BI != BE; ++BI)
for (succ_iterator I = succ_begin(*BI), E = succ_end(*BI); I != E; ++I)
if (!contains(*I)) // Not in current loop?
ExitBlocks.push_back(*I); // It must be an exit block...
if (!std::binary_search(LoopBBs.begin(), LoopBBs.end(), *I))
// Not in current loop? It must be an exit block.
ExitBlocks.push_back(*I);
}