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Record PRE predecessors with a SmallVector instead of a DenseMap, and
avoid a second pred_iterator traversal. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@175001 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -2389,7 +2389,7 @@ bool GVN::processBlock(BasicBlock *BB) {
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/// control flow patterns and attempts to perform simple PRE at the join point.
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bool GVN::performPRE(Function &F) {
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bool Changed = false;
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DenseMap<BasicBlock*, Value*> predMap;
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SmallVector<std::pair<Value*, BasicBlock*>, 8> predMap;
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for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
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DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
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BasicBlock *CurrentBlock = *DI;
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@ -2452,6 +2452,7 @@ bool GVN::performPRE(Function &F) {
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Value* predV = findLeader(P, ValNo);
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if (predV == 0) {
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predMap.push_back(std::make_pair(static_cast<Value *>(0), P));
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PREPred = P;
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++NumWithout;
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} else if (predV == CurInst) {
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@ -2459,7 +2460,7 @@ bool GVN::performPRE(Function &F) {
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NumWithout = 2;
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break;
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} else {
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predMap[P] = predV;
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predMap.push_back(std::make_pair(predV, P));
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++NumWith;
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}
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}
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@ -2514,7 +2515,6 @@ bool GVN::performPRE(Function &F) {
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PREInstr->insertBefore(PREPred->getTerminator());
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PREInstr->setName(CurInst->getName() + ".pre");
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PREInstr->setDebugLoc(CurInst->getDebugLoc());
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predMap[PREPred] = PREInstr;
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VN.add(PREInstr, ValNo);
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++NumGVNPRE;
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@ -2522,13 +2522,14 @@ bool GVN::performPRE(Function &F) {
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addToLeaderTable(ValNo, PREInstr, PREPred);
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// Create a PHI to make the value available in this block.
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pred_iterator PB = pred_begin(CurrentBlock), PE = pred_end(CurrentBlock);
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PHINode* Phi = PHINode::Create(CurInst->getType(), std::distance(PB, PE),
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PHINode* Phi = PHINode::Create(CurInst->getType(), predMap.size(),
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CurInst->getName() + ".pre-phi",
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CurrentBlock->begin());
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for (pred_iterator PI = PB; PI != PE; ++PI) {
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BasicBlock *P = *PI;
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Phi->addIncoming(predMap[P], P);
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for (unsigned i = 0, e = predMap.size(); i != e; ++i) {
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if (Value *V = predMap[i].first)
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Phi->addIncoming(V, predMap[i].second);
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else
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Phi->addIncoming(PREInstr, PREPred);
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}
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VN.add(Phi, ValNo);
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