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pull the predMap densemap out of the inner loop of performPRE, so 

that it isn't reallocated all the time.  This is a tiny speedup for
GVN: 3.90->3.88s

llvm-svn: 60338
This commit is contained in:
Chris Lattner 2008-12-01 07:29:03 +00:00
parent 2b07d3ccde
commit f00aae4968
1 changed files with 4 additions and 2 deletions
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6
llvm/lib/Transforms/Scalar/GVN.cpp
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@ -1225,6 +1225,7 @@ bool GVN::processBlock(DomTreeNode* DTN) {
bool GVN::performPRE(Function& F) {
bool changed = false;
SmallVector<std::pair<TerminatorInst*, unsigned>, 4> toSplit;
DenseMap<BasicBlock*, Value*> predMap;
for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
BasicBlock* CurrentBlock = *DI;
@ -1252,7 +1253,8 @@ bool GVN::performPRE(Function& F) {
unsigned numWith = 0;
unsigned numWithout = 0;
BasicBlock* PREPred = 0;
DenseMap<BasicBlock*, Value*> predMap;
predMap.clear();
for (pred_iterator PI = pred_begin(CurrentBlock),
PE = pred_end(CurrentBlock); PI != PE; ++PI) {
// We're not interested in PRE where the block is its
@ -1359,7 +1361,7 @@ bool GVN::performPRE(Function& F) {
Instruction* erase = BI;
BI++;
DEBUG(cerr << "GVN removed: " << *erase);
DEBUG(cerr << "GVN PRE removed: " << *erase);
MD->removeInstruction(erase);
erase->eraseFromParent();
changed = true;