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Be more aggressive in pruning unnecessary PHI nodes when doing PHI construction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41080 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -749,40 +749,59 @@ Value *GVN::GetValueForBlock(BasicBlock *BB, LoadInst* orig,
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if (Phis.count(BB) == 0)
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Phis.insert(std::make_pair(BB, PN));
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bool all_same = true;
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Value* first = 0;
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// Fill in the incoming values for the block.
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for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI) {
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Value* val = GetValueForBlock(*PI, orig, Phis);
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if (first == 0)
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first = val;
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else if (all_same && first != val)
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all_same = false;
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PN->addIncoming(val, *PI);
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}
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if (all_same) {
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MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
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MD.removeInstruction(PN);
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PN->replaceAllUsesWith(first);
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SmallVector<BasicBlock*, 4> toRemove;
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for (DenseMap<BasicBlock*, Value*>::iterator I = Phis.begin(),
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E = Phis.end(); I != E; ++I)
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if (I->second == PN)
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toRemove.push_back(I->first);
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for (SmallVector<BasicBlock*, 4>::iterator I = toRemove.begin(),
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E= toRemove.end(); I != E; ++I)
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Phis[*I] = first;
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PN->eraseFromParent();
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Phis[BB] = first;
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return first;
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Value* v = PN->hasConstantValue();
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if (v) {
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if (Instruction* inst = dyn_cast<Instruction>(v)) {
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DominatorTree &DT = getAnalysis<DominatorTree>();
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if (DT.dominates(inst, PN)) {
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MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
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MD.removeInstruction(PN);
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PN->replaceAllUsesWith(inst);
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SmallVector<BasicBlock*, 4> toRemove;
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for (DenseMap<BasicBlock*, Value*>::iterator I = Phis.begin(),
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E = Phis.end(); I != E; ++I)
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if (I->second == PN)
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toRemove.push_back(I->first);
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for (SmallVector<BasicBlock*, 4>::iterator I = toRemove.begin(),
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E= toRemove.end(); I != E; ++I)
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Phis[*I] = inst;
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PN->eraseFromParent();
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Phis[BB] = inst;
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return inst;
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}
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} else {
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MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
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MD.removeInstruction(PN);
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PN->replaceAllUsesWith(v);
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SmallVector<BasicBlock*, 4> toRemove;
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for (DenseMap<BasicBlock*, Value*>::iterator I = Phis.begin(),
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E = Phis.end(); I != E; ++I)
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if (I->second == PN)
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toRemove.push_back(I->first);
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for (SmallVector<BasicBlock*, 4>::iterator I = toRemove.begin(),
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E= toRemove.end(); I != E; ++I)
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Phis[*I] = v;
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PN->eraseFromParent();
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Phis[BB] = v;
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return v;
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}
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}
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phiMap[orig->getPointerOperand()].insert(PN);
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@ -915,7 +934,7 @@ bool GVN::processLoad(LoadInst* L,
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return deletedLoad;
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}
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/// buildsets_availout - When calculating availability, handle an instruction
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/// processInstruction - When calculating availability, handle an instruction
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/// by inserting it into the appropriate sets
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bool GVN::processInstruction(Instruction* I,
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ValueNumberedSet& currAvail,
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