forked from OSchip/llvm-project
Rename some variables, only increment BI once at the start of the loop instead of throughout it.
llvm-svn: 60339
This commit is contained in:
Chris Lattner
parent
f00aae4968
commit
6f5bf6a718
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@ -1223,7 +1223,7 @@ bool GVN::processBlock(DomTreeNode* DTN) {
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/// performPRE - Perform a purely local form of PRE that looks for diamond
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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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bool Changed = false;
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SmallVector<std::pair<TerminatorInst*, unsigned>, 4> toSplit;
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DenseMap<BasicBlock*, Value*> predMap;
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for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
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@ -1235,14 +1235,14 @@ bool GVN::performPRE(Function& F) {
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for (BasicBlock::iterator BI = CurrentBlock->begin(),
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BE = CurrentBlock->end(); BI != BE; ) {
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if (isa<AllocationInst>(BI) || isa<TerminatorInst>(BI) ||
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isa<PHINode>(BI) || BI->mayReadFromMemory() ||
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BI->mayWriteToMemory()) {
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BI++;
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continue;
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}
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Instruction *CurInst = BI++;
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uint32_t valno = VN.lookup(BI);
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if (isa<AllocationInst>(CurInst) || isa<TerminatorInst>(CurInst) ||
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isa<PHINode>(CurInst) || CurInst->mayReadFromMemory() ||
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CurInst->mayWriteToMemory())
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continue;
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uint32_t valno = VN.lookup(CurInst);
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// Look for the predecessors for PRE opportunities. We're
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// only trying to solve the basic diamond case, where
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@ -1273,7 +1273,7 @@ bool GVN::performPRE(Function& F) {
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if (predV == localAvail[*PI]->table.end()) {
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PREPred = *PI;
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numWithout++;
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} else if (predV->second == BI) {
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} else if (predV->second == CurInst) {
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numWithout = 2;
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} else {
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predMap[*PI] = predV->second;
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@ -1283,10 +1283,8 @@ bool GVN::performPRE(Function& F) {
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// Don't do PRE when it might increase code size, i.e. when
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// we would need to insert instructions in more than one pred.
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if (numWithout != 1 || numWith == 0) {
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BI++;
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if (numWithout != 1 || numWith == 0)
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continue;
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}
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// We can't do PRE safely on a critical edge, so instead we schedule
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// the edge to be split and perform the PRE the next time we iterate
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@ -1301,8 +1299,6 @@ bool GVN::performPRE(Function& F) {
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if (isCriticalEdge(PREPred->getTerminator(), succNum)) {
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toSplit.push_back(std::make_pair(PREPred->getTerminator(), succNum));
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changed = true;
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BI++;
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continue;
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}
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@ -1311,19 +1307,18 @@ bool GVN::performPRE(Function& F) {
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// will be available in the predecessor by the time we need them. Any
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// that weren't original present will have been instantiated earlier
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// in this loop.
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Instruction* PREInstr = BI->clone();
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Instruction* PREInstr = CurInst->clone();
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bool success = true;
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for (unsigned i = 0; i < BI->getNumOperands(); ++i) {
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Value* op = BI->getOperand(i);
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if (isa<Argument>(op) || isa<Constant>(op) || isa<GlobalValue>(op))
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PREInstr->setOperand(i, op);
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else {
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Value* V = lookupNumber(PREPred, VN.lookup(op));
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if (!V) {
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success = false;
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break;
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} else
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PREInstr->setOperand(i, V);
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for (unsigned i = 0, e = CurInst->getNumOperands(); i != e; ++i) {
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Value *Op = PREInstr->getOperand(i);
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if (isa<Argument>(Op) || isa<Constant>(Op) || isa<GlobalValue>(Op))
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continue;
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if (Value *V = lookupNumber(PREPred, VN.lookup(Op))) {
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PREInstr->setOperand(i, V);
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} else {
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success = false;
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break;
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}
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}
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@ -1332,12 +1327,11 @@ bool GVN::performPRE(Function& F) {
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// are not value numbered precisely.
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if (!success) {
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delete PREInstr;
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BI++;
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continue;
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}
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PREInstr->insertBefore(PREPred->getTerminator());
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PREInstr->setName(BI->getName() + ".pre");
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PREInstr->setName(CurInst->getName() + ".pre");
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predMap[PREPred] = PREInstr;
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VN.add(PREInstr, valno);
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NumGVNPRE++;
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@ -1346,8 +1340,8 @@ bool GVN::performPRE(Function& F) {
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localAvail[PREPred]->table.insert(std::make_pair(valno, PREInstr));
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// Create a PHI to make the value available in this block.
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PHINode* Phi = PHINode::Create(BI->getType(),
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BI->getName() + ".pre-phi",
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PHINode* Phi = PHINode::Create(CurInst->getType(),
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CurInst->getName() + ".pre-phi",
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CurrentBlock->begin());
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for (pred_iterator PI = pred_begin(CurrentBlock),
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PE = pred_end(CurrentBlock); PI != PE; ++PI)
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@ -1356,15 +1350,13 @@ bool GVN::performPRE(Function& F) {
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VN.add(Phi, valno);
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localAvail[CurrentBlock]->table[valno] = Phi;
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BI->replaceAllUsesWith(Phi);
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VN.erase(BI);
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CurInst->replaceAllUsesWith(Phi);
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VN.erase(CurInst);
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Instruction* erase = BI;
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BI++;
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DEBUG(cerr << "GVN PRE removed: " << *erase);
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MD->removeInstruction(erase);
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erase->eraseFromParent();
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changed = true;
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DEBUG(cerr << "GVN PRE removed: " << *CurInst);
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MD->removeInstruction(CurInst);
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CurInst->eraseFromParent();
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Changed = true;
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}
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}
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@ -1372,7 +1364,7 @@ bool GVN::performPRE(Function& F) {
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I = toSplit.begin(), E = toSplit.end(); I != E; ++I)
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SplitCriticalEdge(I->first, I->second, this);
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return changed || toSplit.size();
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return Changed || toSplit.size();
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}
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// iterateOnFunction - Executes one iteration of GVN
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