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Speed up Loop::isLCSSAForm by using a binary search and single-entry cache. 

This reduces LCSSA pass time from 1.5s to 0.96s when run on eon in release+asserts mode.

llvm-svn: 29464
This commit is contained in:
Chris Lattner 2006-08-02 00:14:16 +00:00
parent 5a2bc786be
commit 4d074f795a
1 changed files with 14 additions and 6 deletions
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18
llvm/lib/Analysis/LoopInfo.cpp
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@ -481,9 +481,14 @@ Value *Loop::getTripCount() const {
/// isLCSSAForm - Return true if the Loop is in LCSSA form /// isLCSSAForm - Return true if the Loop is in LCSSA form
bool Loop::isLCSSAForm() const { bool Loop::isLCSSAForm() const {
for (Loop::block_iterator BB = block_begin(), E = block_end(); // Sort the blocks vector so that we can use binary search to do quick
BB != E; ++BB) { // lookups.
for (BasicBlock::iterator I = (*BB)->begin(), E = (*BB)->end(); I != E; ++I) std::vector<BasicBlock*> LoopBBs(block_begin(), block_end());
std::sort(LoopBBs.begin(), LoopBBs.end());
for (unsigned i = 0, e = LoopBBs.size(); i != e; ++i) {
BasicBlock *BB = LoopBBs[i];
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E; for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E;
++UI) { ++UI) {
BasicBlock *UserBB = cast<Instruction>(*UI)->getParent(); BasicBlock *UserBB = cast<Instruction>(*UI)->getParent();
@ -492,9 +497,12 @@ bool Loop::isLCSSAForm() const {
UserBB = p->getIncomingBlock(OperandNo/2); UserBB = p->getIncomingBlock(OperandNo/2);
} }
if (!contains(UserBB)) { // Check the current block, as a fast-path. Most values are used in the
// same block they are defined in.
if (UserBB != BB &&
// Otherwise, binary search LoopBBs for this block.
!std::binary_search(LoopBBs.begin(), LoopBBs.end(), UserBB))
return false; return false;
}
} }
} }