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Record PRE predecessors with a SmallVector instead of a DenseMap, and

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avoid a second pred_iterator traversal.

llvm-svn: 175001
This commit is contained in:
Dan Gohman 2013-02-12 19:49:10 +00:00
parent 3eb029b4c7
commit a04e614c0f
1 changed files with 9 additions and 8 deletions
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17
lib/Transforms/Scalar/GVN.cpp
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@ -2389,7 +2389,7 @@ bool GVN::processBlock(BasicBlock *BB) {
/// control flow patterns and attempts to perform simple PRE at the join point. /// control flow patterns and attempts to perform simple PRE at the join point.
bool GVN::performPRE(Function &F) { bool GVN::performPRE(Function &F) {
bool Changed = false; bool Changed = false;
DenseMap<BasicBlock*, Value*> predMap; SmallVector<std::pair<Value*, BasicBlock*>, 8> predMap;
for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()), for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) { DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
BasicBlock *CurrentBlock = *DI; BasicBlock *CurrentBlock = *DI;
@ -2452,6 +2452,7 @@ bool GVN::performPRE(Function &F) {
Value* predV = findLeader(P, ValNo); Value* predV = findLeader(P, ValNo);
if (predV == 0) { if (predV == 0) {
predMap.push_back(std::make_pair(static_cast<Value *>(0), P));
PREPred = P; PREPred = P;
++NumWithout; ++NumWithout;
} else if (predV == CurInst) { } else if (predV == CurInst) {
@ -2459,7 +2460,7 @@ bool GVN::performPRE(Function &F) {
NumWithout = 2; NumWithout = 2;
break; break;
} else { } else {
predMap[P] = predV; predMap.push_back(std::make_pair(predV, P));
++NumWith; ++NumWith;
} }
} }
@ -2514,7 +2515,6 @@ bool GVN::performPRE(Function &F) {
PREInstr->insertBefore(PREPred->getTerminator()); PREInstr->insertBefore(PREPred->getTerminator());
PREInstr->setName(CurInst->getName() + ".pre"); PREInstr->setName(CurInst->getName() + ".pre");
PREInstr->setDebugLoc(CurInst->getDebugLoc()); PREInstr->setDebugLoc(CurInst->getDebugLoc());
predMap[PREPred] = PREInstr;
VN.add(PREInstr, ValNo); VN.add(PREInstr, ValNo);
++NumGVNPRE; ++NumGVNPRE;
@ -2522,13 +2522,14 @@ bool GVN::performPRE(Function &F) {
addToLeaderTable(ValNo, PREInstr, PREPred); addToLeaderTable(ValNo, PREInstr, PREPred);
// Create a PHI to make the value available in this block. // Create a PHI to make the value available in this block.
pred_iterator PB = pred_begin(CurrentBlock), PE = pred_end(CurrentBlock); PHINode* Phi = PHINode::Create(CurInst->getType(), predMap.size(),
PHINode* Phi = PHINode::Create(CurInst->getType(), std::distance(PB, PE),
CurInst->getName() + ".pre-phi", CurInst->getName() + ".pre-phi",
CurrentBlock->begin()); CurrentBlock->begin());
for (pred_iterator PI = PB; PI != PE; ++PI) { for (unsigned i = 0, e = predMap.size(); i != e; ++i) {
BasicBlock *P = *PI; if (Value *V = predMap[i].first)
Phi->addIncoming(predMap[P], P); Phi->addIncoming(V, predMap[i].second);
else
Phi->addIncoming(PREInstr, PREPred);
} }
VN.add(Phi, ValNo); VN.add(Phi, ValNo);