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[NewGVN] Split OpPHI detection and creation.
It also adds a check making sure PHIs for operands are all in the same block. Patch by Daniel Berlin <dberlin@dberlin.org> Reviewers: dberlin, davide Differential Revision: https://reviews.llvm.org/D43865 llvm-svn: 330444
This commit is contained in:
Florian Hahn
parent
8dc720bb33
commit
39281bf454
@ -2724,9 +2724,14 @@ NewGVN::makePossiblePHIOfOps(Instruction *I,
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MemAccess->getDefiningAccess()->getBlock() == I->getParent())
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return nullptr;
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SmallPtrSet<const Value *, 10> VisitedOps;
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// Convert op of phis to phi of ops
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for (auto *Op : I->operand_values()) {
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SmallPtrSet<const Value *, 10> VisitedOps;
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SmallVector<Value *, 4> Ops(I->operand_values());
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BasicBlock *SamePHIBlock = nullptr;
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PHINode *OpPHI = nullptr;
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if (!DebugCounter::shouldExecute(PHIOfOpsCounter))
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return nullptr;
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for (auto *Op : Ops) {
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if (!isa<PHINode>(Op)) {
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auto *ValuePHI = RealToTemp.lookup(Op);
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if (!ValuePHI)
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@ -2734,116 +2739,125 @@ NewGVN::makePossiblePHIOfOps(Instruction *I,
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DEBUG(dbgs() << "Found possible dependent phi of ops\n");
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Op = ValuePHI;
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}
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auto *OpPHI = cast<PHINode>(Op);
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// No point in doing this for one-operand phis.
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if (OpPHI->getNumOperands() == 1)
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continue;
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if (!DebugCounter::shouldExecute(PHIOfOpsCounter))
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return nullptr;
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SmallVector<ValPair, 4> Ops;
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SmallPtrSet<Value *, 4> Deps;
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auto *PHIBlock = getBlockForValue(OpPHI);
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RevisitOnReachabilityChange[PHIBlock].reset(InstrToDFSNum(I));
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for (unsigned PredNum = 0; PredNum < OpPHI->getNumOperands(); ++PredNum) {
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auto *PredBB = OpPHI->getIncomingBlock(PredNum);
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Value *FoundVal = nullptr;
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// We could just skip unreachable edges entirely but it's tricky to do
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// with rewriting existing phi nodes.
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if (ReachableEdges.count({PredBB, PHIBlock})) {
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// Clone the instruction, create an expression from it that is
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// translated back into the predecessor, and see if we have a leader.
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Instruction *ValueOp = I->clone();
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SmallPtrSet<Value *, 4> CurrentDeps;
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if (MemAccess)
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TempToMemory.insert({ValueOp, MemAccess});
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bool SafeForPHIOfOps = true;
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VisitedOps.clear();
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for (auto &Op : ValueOp->operands()) {
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auto *OrigOp = &*Op;
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// When these operand changes, it could change whether there is a
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// leader for us or not, so we have to add additional users.
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if (isa<PHINode>(Op)) {
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Op = Op->DoPHITranslation(PHIBlock, PredBB);
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if (Op != OrigOp && Op != I)
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CurrentDeps.insert(Op);
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} else if (auto *ValuePHI = RealToTemp.lookup(Op)) {
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if (getBlockForValue(ValuePHI) == PHIBlock)
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Op = ValuePHI->getIncomingValueForBlock(PredBB);
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}
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// If we phi-translated the op, it must be safe.
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SafeForPHIOfOps =
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SafeForPHIOfOps &&
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(Op != OrigOp || OpIsSafeForPHIOfOps(Op, PHIBlock, VisitedOps));
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}
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// FIXME: For those things that are not safe we could generate
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// expressions all the way down, and see if this comes out to a
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// constant. For anything where that is true, and unsafe, we should
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// have made a phi-of-ops (or value numbered it equivalent to something)
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// for the pieces already.
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FoundVal = !SafeForPHIOfOps ? nullptr
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: findLeaderForInst(ValueOp, Visited,
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MemAccess, I, PredBB);
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ValueOp->deleteValue();
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if (!FoundVal) {
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// We failed to find a leader for the current ValueOp, but this might
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// change in case of the translated operands change.
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if (SafeForPHIOfOps)
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for (auto Dep : CurrentDeps)
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addAdditionalUsers(Dep, I);
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return nullptr;
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}
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Deps.insert(CurrentDeps.begin(), CurrentDeps.end());
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} else {
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DEBUG(dbgs() << "Skipping phi of ops operand for incoming block "
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<< getBlockName(PredBB)
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<< " because the block is unreachable\n");
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FoundVal = UndefValue::get(I->getType());
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RevisitOnReachabilityChange[PHIBlock].set(InstrToDFSNum(I));
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}
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Ops.push_back({FoundVal, PredBB});
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DEBUG(dbgs() << "Found phi of ops operand " << *FoundVal << " in "
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<< getBlockName(PredBB) << "\n");
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}
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for (auto Dep : Deps)
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addAdditionalUsers(Dep, I);
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sortPHIOps(Ops);
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auto *E = performSymbolicPHIEvaluation(Ops, I, PHIBlock);
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if (isa<ConstantExpression>(E) || isa<VariableExpression>(E)) {
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OpPHI = cast<PHINode>(Op);
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if (!SamePHIBlock) {
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SamePHIBlock = getBlockForValue(OpPHI);
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} else if (SamePHIBlock != getBlockForValue(OpPHI)) {
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DEBUG(dbgs()
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<< "Not creating real PHI of ops because it simplified to existing "
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"value or constant\n");
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return E;
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<< "PHIs for operands are not all in the same block, aborting\n");
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return nullptr;
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}
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auto *ValuePHI = RealToTemp.lookup(I);
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bool NewPHI = false;
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if (!ValuePHI) {
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ValuePHI =
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PHINode::Create(I->getType(), OpPHI->getNumOperands(), "phiofops");
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addPhiOfOps(ValuePHI, PHIBlock, I);
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NewPHI = true;
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NumGVNPHIOfOpsCreated++;
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// No point in doing this for one-operand phis.
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if (OpPHI->getNumOperands() == 1) {
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OpPHI = nullptr;
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continue;
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}
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if (NewPHI) {
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for (auto PHIOp : Ops)
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ValuePHI->addIncoming(PHIOp.first, PHIOp.second);
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} else {
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TempToBlock[ValuePHI] = PHIBlock;
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unsigned int i = 0;
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for (auto PHIOp : Ops) {
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ValuePHI->setIncomingValue(i, PHIOp.first);
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ValuePHI->setIncomingBlock(i, PHIOp.second);
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++i;
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}
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}
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RevisitOnReachabilityChange[PHIBlock].set(InstrToDFSNum(I));
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DEBUG(dbgs() << "Created phi of ops " << *ValuePHI << " for " << *I
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<< "\n");
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}
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if (!OpPHI)
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return nullptr;
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SmallVector<ValPair, 4> PHIOps;
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SmallPtrSet<Value *, 4> Deps;
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auto *PHIBlock = getBlockForValue(OpPHI);
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RevisitOnReachabilityChange[PHIBlock].reset(InstrToDFSNum(I));
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for (unsigned PredNum = 0; PredNum < OpPHI->getNumOperands(); ++PredNum) {
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auto *PredBB = OpPHI->getIncomingBlock(PredNum);
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Value *FoundVal = nullptr;
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SmallPtrSet<Value *, 4> CurrentDeps;
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// We could just skip unreachable edges entirely but it's tricky to do
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// with rewriting existing phi nodes.
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if (ReachableEdges.count({PredBB, PHIBlock})) {
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// Clone the instruction, create an expression from it that is
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// translated back into the predecessor, and see if we have a leader.
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Instruction *ValueOp = I->clone();
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if (MemAccess)
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TempToMemory.insert({ValueOp, MemAccess});
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bool SafeForPHIOfOps = true;
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VisitedOps.clear();
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for (auto &Op : ValueOp->operands()) {
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auto *OrigOp = &*Op;
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// When these operand changes, it could change whether there is a
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// leader for us or not, so we have to add additional users.
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if (isa<PHINode>(Op)) {
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Op = Op->DoPHITranslation(PHIBlock, PredBB);
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if (Op != OrigOp && Op != I)
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CurrentDeps.insert(Op);
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} else if (auto *ValuePHI = RealToTemp.lookup(Op)) {
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if (getBlockForValue(ValuePHI) == PHIBlock)
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Op = ValuePHI->getIncomingValueForBlock(PredBB);
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}
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// If we phi-translated the op, it must be safe.
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SafeForPHIOfOps =
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SafeForPHIOfOps &&
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(Op != OrigOp || OpIsSafeForPHIOfOps(Op, PHIBlock, VisitedOps));
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}
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// FIXME: For those things that are not safe we could generate
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// expressions all the way down, and see if this comes out to a
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// constant. For anything where that is true, and unsafe, we should
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// have made a phi-of-ops (or value numbered it equivalent to something)
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// for the pieces already.
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FoundVal = !SafeForPHIOfOps ? nullptr
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: findLeaderForInst(ValueOp, Visited,
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MemAccess, I, PredBB);
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ValueOp->deleteValue();
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if (!FoundVal) {
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// We failed to find a leader for the current ValueOp, but this might
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// change in case of the translated operands change.
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if (SafeForPHIOfOps)
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for (auto Dep : CurrentDeps)
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addAdditionalUsers(Dep, I);
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return nullptr;
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}
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Deps.insert(CurrentDeps.begin(), CurrentDeps.end());
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} else {
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DEBUG(dbgs() << "Skipping phi of ops operand for incoming block "
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<< getBlockName(PredBB)
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<< " because the block is unreachable\n");
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FoundVal = UndefValue::get(I->getType());
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RevisitOnReachabilityChange[PHIBlock].set(InstrToDFSNum(I));
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}
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PHIOps.push_back({FoundVal, PredBB});
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DEBUG(dbgs() << "Found phi of ops operand " << *FoundVal << " in "
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<< getBlockName(PredBB) << "\n");
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}
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for (auto Dep : Deps)
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addAdditionalUsers(Dep, I);
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sortPHIOps(PHIOps);
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auto *E = performSymbolicPHIEvaluation(PHIOps, I, PHIBlock);
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if (isa<ConstantExpression>(E) || isa<VariableExpression>(E)) {
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DEBUG(dbgs()
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<< "Not creating real PHI of ops because it simplified to existing "
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"value or constant\n");
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return E;
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}
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return nullptr;
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auto *ValuePHI = RealToTemp.lookup(I);
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bool NewPHI = false;
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if (!ValuePHI) {
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ValuePHI =
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PHINode::Create(I->getType(), OpPHI->getNumOperands(), "phiofops");
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addPhiOfOps(ValuePHI, PHIBlock, I);
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NewPHI = true;
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NumGVNPHIOfOpsCreated++;
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}
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if (NewPHI) {
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for (auto PHIOp : PHIOps)
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ValuePHI->addIncoming(PHIOp.first, PHIOp.second);
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} else {
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TempToBlock[ValuePHI] = PHIBlock;
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unsigned int i = 0;
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for (auto PHIOp : PHIOps) {
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ValuePHI->setIncomingValue(i, PHIOp.first);
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ValuePHI->setIncomingBlock(i, PHIOp.second);
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++i;
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}
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}
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RevisitOnReachabilityChange[PHIBlock].set(InstrToDFSNum(I));
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DEBUG(dbgs() << "Created phi of ops " << *ValuePHI << " for " << *I << "\n");
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return E;
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}
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// The algorithm initially places the values of the routine in the TOP
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@ -54,3 +54,54 @@ critedge: ; preds = %lr.ph, %bb1
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end:
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ret void
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}
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; In this test case a temporary PhiOfOps node gets moved to BB with more
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; predecessors, so a new one needs to be created.
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define void @test2() {
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; CHECK-LABEL: @test2(
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; CHECK-NEXT: br label [[BB1:%.*]]
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; CHECK: bb1:
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; CHECK-NEXT: [[STOREMERGE:%.*]] = phi i32 [ 0, [[TMP0:%.*]] ], [ [[ADD:%.*]], [[CRITEDGE:%.*]] ]
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; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i32 [[STOREMERGE]], 0
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; CHECK-NEXT: br i1 [[CMP1]], label [[LR_PH:%.*]], label [[CRITEDGE]]
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; CHECK: lr.ph:
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; CHECK-NEXT: br i1 undef, label [[SPLIT1:%.*]], label [[SPLIT2:%.*]]
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; CHECK: split1:
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; CHECK-NEXT: br label [[CRITEDGE]]
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; CHECK: split2:
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; CHECK-NEXT: br label [[CRITEDGE]]
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; CHECK: critedge:
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; CHECK-NEXT: [[PHIOFOPS1:%.*]] = phi i1 [ false, [[BB1]] ], [ true, [[SPLIT2]] ], [ true, [[SPLIT1]] ]
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; CHECK-NEXT: [[PHIOFOPS:%.*]] = phi i1 [ [[CMP1]], [[BB1]] ], [ true, [[SPLIT2]] ], [ true, [[SPLIT1]] ]
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; CHECK-NEXT: [[LCSSA:%.*]] = phi i32 [ 0, [[BB1]] ], [ -1, [[SPLIT1]] ], [ -1, [[SPLIT2]] ]
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; CHECK-NEXT: [[ADD]] = add nsw i32 [[STOREMERGE]], -1
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; CHECK-NEXT: br i1 [[PHIOFOPS]], label [[BB1]], label [[EXIT:%.*]]
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; CHECK: exit:
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; CHECK-NEXT: ret void
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;
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br label %bb1
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bb1: ; preds = %critedge, %0
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%storemerge = phi i32 [ 0, %0 ], [ %add, %critedge ]
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%cmp1 = icmp eq i32 %storemerge, 0
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br i1 %cmp1, label %lr.ph, label %critedge
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lr.ph: ; preds = %bb1
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br i1 undef, label %split1, label %split2
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split1: ; preds = %lr.ph
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br label %critedge
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split2: ; preds = %lr.ph
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br label %critedge
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critedge: ; preds = %split1, %split2, %bb1
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%lcssa = phi i32 [ 0, %bb1 ], [ -1, %split1 ], [ -1, %split2 ]
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%cmp2 = icmp ne i32 %lcssa, 0
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%brmerge = or i1 %cmp1, %cmp2
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%add = add nsw i32 %storemerge, -1
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br i1 %brmerge, label %bb1, label %exit
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exit: ; preds = %critedge
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ret void
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}
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