diff options
| -rw-r--r-- | llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h | 26 | ||||
| -rw-r--r-- | llvm/lib/Analysis/MemoryDependenceAnalysis.cpp | 337 | ||||
| -rw-r--r-- | llvm/lib/Transforms/Scalar/GVN.cpp | 39 | ||||
| -rw-r--r-- | llvm/test/Transforms/GVN/rle.ll | 51 |
4 files changed, 108 insertions, 345 deletions
diff --git a/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h b/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h index b55be29d2eb..b46563b475e 100644 --- a/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h +++ b/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h @@ -31,6 +31,7 @@ namespace llvm { class MemoryDependenceAnalysis; class PredIteratorCache; class DominatorTree; + class PHITransAddr; /// MemDepResult - A memory dependence query can return one of three different /// answers, described below. @@ -245,29 +246,6 @@ namespace llvm { BasicBlock *BB, SmallVectorImpl<NonLocalDepEntry> &Result); - /// GetPHITranslatedValue - Find an available version of the specified value - /// PHI translated across the specified edge. If MemDep isn't able to - /// satisfy this request, it returns null. - Value *GetPHITranslatedValue(Value *V, - BasicBlock *CurBB, BasicBlock *PredBB, - const TargetData *TD) const; - - /// GetAvailablePHITranslatedValue - Return the value computed by - /// PHITranslatePointer if it dominates PredBB, otherwise return null. - Value *GetAvailablePHITranslatedValue(Value *V, - BasicBlock *CurBB, BasicBlock *PredBB, - const TargetData *TD, - const DominatorTree &DT) const; - - /// InsertPHITranslatedPointer - Insert a computation of the PHI translated - /// version of 'V' for the edge PredBB->CurBB into the end of the PredBB - /// block. All newly created instructions are added to the NewInsts list. - Value *InsertPHITranslatedPointer(Value *V, - BasicBlock *CurBB, BasicBlock *PredBB, - const TargetData *TD, - const DominatorTree &DT, - SmallVectorImpl<Instruction*> &NewInsts) const; - /// removeInstruction - Remove an instruction from the dependence analysis, /// updating the dependence of instructions that previously depended on it. void removeInstruction(Instruction *InstToRemove); @@ -288,7 +266,7 @@ namespace llvm { MemDepResult getCallSiteDependencyFrom(CallSite C, bool isReadOnlyCall, BasicBlock::iterator ScanIt, BasicBlock *BB); - bool getNonLocalPointerDepFromBB(Value *Pointer, uint64_t Size, + bool getNonLocalPointerDepFromBB(const PHITransAddr &Pointer, uint64_t Size, bool isLoad, BasicBlock *BB, SmallVectorImpl<NonLocalDepEntry> &Result, DenseMap<BasicBlock*, Value*> &Visited, diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp index ccd8d8c8aee..44487f2ff98 100644 --- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp +++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp @@ -23,6 +23,7 @@ #include "llvm/Analysis/Dominators.h" #include "llvm/Analysis/InstructionSimplify.h" #include "llvm/Analysis/MemoryBuiltins.h" +#include "llvm/Analysis/PHITransAddr.h" #include "llvm/ADT/Statistic.h" #include "llvm/ADT/STLExtras.h" #include "llvm/Support/PredIteratorCache.h" @@ -587,12 +588,14 @@ getNonLocalPointerDependency(Value *Pointer, bool isLoad, BasicBlock *FromBB, const Type *EltTy = cast<PointerType>(Pointer->getType())->getElementType(); uint64_t PointeeSize = AA->getTypeStoreSize(EltTy); + PHITransAddr Address(Pointer, TD); + // This is the set of blocks we've inspected, and the pointer we consider in // each block. Because of critical edges, we currently bail out if querying // a block with multiple different pointers. This can happen during PHI // translation. DenseMap<BasicBlock*, Value*> Visited; - if (!getNonLocalPointerDepFromBB(Pointer, PointeeSize, isLoad, FromBB, + if (!getNonLocalPointerDepFromBB(Address, PointeeSize, isLoad, FromBB, Result, Visited, true)) return; Result.clear(); @@ -707,275 +710,6 @@ SortNonLocalDepInfoCache(MemoryDependenceAnalysis::NonLocalDepInfo &Cache, } } -/// isPHITranslatable - Return true if the specified computation is derived from -/// a PHI node in the current block and if it is simple enough for us to handle. -static bool isPHITranslatable(Instruction *Inst) { - if (isa<PHINode>(Inst)) - return true; - - // We can handle bitcast of a PHI, but the PHI needs to be in the same block - // as the bitcast. - if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) { - Instruction *OpI = dyn_cast<Instruction>(BC->getOperand(0)); - if (OpI == 0 || OpI->getParent() != Inst->getParent()) - return true; - return isPHITranslatable(OpI); - } - - // We can translate a GEP if all of its operands defined in this block are phi - // translatable. - if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) { - for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) { - Instruction *OpI = dyn_cast<Instruction>(GEP->getOperand(i)); - if (OpI == 0 || OpI->getParent() != Inst->getParent()) - continue; - - if (!isPHITranslatable(OpI)) - return false; - } - return true; - } - - if (Inst->getOpcode() == Instruction::Add && - isa<ConstantInt>(Inst->getOperand(1))) { - Instruction *OpI = dyn_cast<Instruction>(Inst->getOperand(0)); - if (OpI == 0 || OpI->getParent() != Inst->getParent()) - return true; - return isPHITranslatable(OpI); - } - - // cerr << "MEMDEP: Could not PHI translate: " << *Pointer; - // if (isa<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(PtrInst)) - // cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0); - - return false; -} - -/// GetPHITranslatedValue - Given a computation that satisfied the -/// isPHITranslatable predicate, see if we can translate the computation into -/// the specified predecessor block. If so, return that value. -Value *MemoryDependenceAnalysis:: -GetPHITranslatedValue(Value *InVal, BasicBlock *CurBB, BasicBlock *Pred, - const TargetData *TD) const { - // If the input value is not an instruction, or if it is not defined in CurBB, - // then we don't need to phi translate it. - Instruction *Inst = dyn_cast<Instruction>(InVal); - if (Inst == 0 || Inst->getParent() != CurBB) - return InVal; - - if (PHINode *PN = dyn_cast<PHINode>(Inst)) - return PN->getIncomingValueForBlock(Pred); - - // Handle bitcast of PHI. - if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) { - // PHI translate the input operand. - Value *PHIIn = GetPHITranslatedValue(BC->getOperand(0), CurBB, Pred, TD); - if (PHIIn == 0) return 0; - - // Constants are trivial to phi translate. - if (Constant *C = dyn_cast<Constant>(PHIIn)) - return ConstantExpr::getBitCast(C, BC->getType()); - - // Otherwise we have to see if a bitcasted version of the incoming pointer - // is available. If so, we can use it, otherwise we have to fail. - for (Value::use_iterator UI = PHIIn->use_begin(), E = PHIIn->use_end(); - UI != E; ++UI) { - if (BitCastInst *BCI = dyn_cast<BitCastInst>(*UI)) - if (BCI->getType() == BC->getType()) - return BCI; - } - return 0; - } - - // Handle getelementptr with at least one PHI translatable operand. - if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) { - SmallVector<Value*, 8> GEPOps; - BasicBlock *CurBB = GEP->getParent(); - for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) { - Value *GEPOp = GEP->getOperand(i); - // No PHI translation is needed of operands whose values are live in to - // the predecessor block. - if (!isa<Instruction>(GEPOp) || - cast<Instruction>(GEPOp)->getParent() != CurBB) { - GEPOps.push_back(GEPOp); - continue; - } - - // If the operand is a phi node, do phi translation. - Value *InOp = GetPHITranslatedValue(GEPOp, CurBB, Pred, TD); - if (InOp == 0) return 0; - - GEPOps.push_back(InOp); - } - - // Simplify the GEP to handle 'gep x, 0' -> x etc. - if (Value *V = SimplifyGEPInst(&GEPOps[0], GEPOps.size(), TD)) - return V; - - // Scan to see if we have this GEP available. - Value *APHIOp = GEPOps[0]; - for (Value::use_iterator UI = APHIOp->use_begin(), E = APHIOp->use_end(); - UI != E; ++UI) { - if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(*UI)) - if (GEPI->getType() == GEP->getType() && - GEPI->getNumOperands() == GEPOps.size() && - GEPI->getParent()->getParent() == CurBB->getParent()) { - bool Mismatch = false; - for (unsigned i = 0, e = GEPOps.size(); i != e; ++i) - if (GEPI->getOperand(i) != GEPOps[i]) { - Mismatch = true; - break; - } - if (!Mismatch) - return GEPI; - } - } - return 0; - } - - // Handle add with a constant RHS. - if (Inst->getOpcode() == Instruction::Add && - isa<ConstantInt>(Inst->getOperand(1))) { - // PHI translate the LHS. - Value *LHS; - Constant *RHS = cast<ConstantInt>(Inst->getOperand(1)); - Instruction *OpI = dyn_cast<Instruction>(Inst->getOperand(0)); - bool isNSW = cast<BinaryOperator>(Inst)->hasNoSignedWrap(); - bool isNUW = cast<BinaryOperator>(Inst)->hasNoUnsignedWrap(); - - if (OpI == 0 || OpI->getParent() != Inst->getParent()) - LHS = Inst->getOperand(0); - else { - LHS = GetPHITranslatedValue(Inst->getOperand(0), CurBB, Pred, TD); - if (LHS == 0) - return 0; - } - - // If the PHI translated LHS is an add of a constant, fold the immediates. - if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(LHS)) - if (BOp->getOpcode() == Instruction::Add) - if (ConstantInt *CI = dyn_cast<ConstantInt>(BOp->getOperand(1))) { - LHS = BOp->getOperand(0); - RHS = ConstantExpr::getAdd(RHS, CI); - isNSW = isNUW = false; - } - - // See if the add simplifies away. - if (Value *Res = SimplifyAddInst(LHS, RHS, isNSW, isNUW, TD)) - return Res; - - // Otherwise, see if we have this add available somewhere. - for (Value::use_iterator UI = LHS->use_begin(), E = LHS->use_end(); - UI != E; ++UI) { - if (BinaryOperator *BO = dyn_cast<BinaryOperator>(*UI)) - if (BO->getOperand(0) == LHS && BO->getOperand(1) == RHS && - BO->getParent()->getParent() == CurBB->getParent()) - return BO; - } - - return 0; - } - - return 0; -} - -/// GetAvailablePHITranslatePointer - Return the value computed by -/// PHITranslatePointer if it dominates PredBB, otherwise return null. -Value *MemoryDependenceAnalysis:: -GetAvailablePHITranslatedValue(Value *V, - BasicBlock *CurBB, BasicBlock *PredBB, - const TargetData *TD, - const DominatorTree &DT) const { - // See if PHI translation succeeds. - V = GetPHITranslatedValue(V, CurBB, PredBB, TD); - if (V == 0) return 0; - - // Make sure the value is live in the predecessor. - if (Instruction *Inst = dyn_cast_or_null<Instruction>(V)) - if (!DT.dominates(Inst->getParent(), PredBB)) - return 0; - return V; -} - - -/// InsertPHITranslatedPointer - Insert a computation of the PHI translated -/// version of 'V' for the edge PredBB->CurBB into the end of the PredBB -/// block. All newly created instructions are added to the NewInsts list. -/// -Value *MemoryDependenceAnalysis:: -InsertPHITranslatedPointer(Value *InVal, BasicBlock *CurBB, - BasicBlock *PredBB, const TargetData *TD, - const DominatorTree &DT, - SmallVectorImpl<Instruction*> &NewInsts) const { - // See if we have a version of this value already available and dominating - // PredBB. If so, there is no need to insert a new copy. - if (Value *Res = GetAvailablePHITranslatedValue(InVal, CurBB, PredBB, TD, DT)) - return Res; - - // If we don't have an available version of this value, it must be an - // instruction. - Instruction *Inst = cast<Instruction>(InVal); - - // Handle bitcast of PHI translatable value. - if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) { - Value *OpVal = InsertPHITranslatedPointer(BC->getOperand(0), - CurBB, PredBB, TD, DT, NewInsts); - if (OpVal == 0) return 0; - - // Otherwise insert a bitcast at the end of PredBB. - BitCastInst *New = new BitCastInst(OpVal, InVal->getType(), - InVal->getName()+".phi.trans.insert", - PredBB->getTerminator()); - NewInsts.push_back(New); - return New; - } - - // Handle getelementptr with at least one PHI operand. - if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) { - SmallVector<Value*, 8> GEPOps; - BasicBlock *CurBB = GEP->getParent(); - for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) { - Value *OpVal = InsertPHITranslatedPointer(GEP->getOperand(i), - CurBB, PredBB, TD, DT, NewInsts); - if (OpVal == 0) return 0; - GEPOps.push_back(OpVal); - } - - GetElementPtrInst *Result = - GetElementPtrInst::Create(GEPOps[0], GEPOps.begin()+1, GEPOps.end(), - InVal->getName()+".phi.trans.insert", - PredBB->getTerminator()); - Result->setIsInBounds(GEP->isInBounds()); - NewInsts.push_back(Result); - return Result; - } - -#if 0 - // FIXME: This code works, but it is unclear that we actually want to insert - // a big chain of computation in order to make a value available in a block. - // This needs to be evaluated carefully to consider its cost trade offs. - - // Handle add with a constant RHS. - if (Inst->getOpcode() == Instruction::Add && - isa<ConstantInt>(Inst->getOperand(1))) { - // PHI translate the LHS. - Value *OpVal = InsertPHITranslatedPointer(Inst->getOperand(0), - CurBB, PredBB, TD, DT, NewInsts); - if (OpVal == 0) return 0; - - BinaryOperator *Res = BinaryOperator::CreateAdd(OpVal, Inst->getOperand(1), - InVal->getName()+".phi.trans.insert", - PredBB->getTerminator()); - Res->setHasNoSignedWrap(cast<BinaryOperator>(Inst)->hasNoSignedWrap()); - Res->setHasNoUnsignedWrap(cast<BinaryOperator>(Inst)->hasNoUnsignedWrap()); - NewInsts.push_back(Res); - return Res; - } -#endif - - return 0; -} - /// getNonLocalPointerDepFromBB - Perform a dependency query based on /// pointer/pointeesize starting at the end of StartBB. Add any clobber/def /// results to the results vector and keep track of which blocks are visited in @@ -989,14 +723,14 @@ InsertPHITranslatedPointer(Value *InVal, BasicBlock *CurBB, /// not compute dependence information for some reason. This should be treated /// as a clobber dependence on the first instruction in the predecessor block. bool MemoryDependenceAnalysis:: -getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize, +getNonLocalPointerDepFromBB(const PHITransAddr &Pointer, uint64_t PointeeSize, bool isLoad, BasicBlock *StartBB, SmallVectorImpl<NonLocalDepEntry> &Result, DenseMap<BasicBlock*, Value*> &Visited, bool SkipFirstBlock) { // Look up the cached info for Pointer. - ValueIsLoadPair CacheKey(Pointer, isLoad); + ValueIsLoadPair CacheKey(Pointer.getAddr(), isLoad); std::pair<BBSkipFirstBlockPair, NonLocalDepInfo> *CacheInfo = &NonLocalPointerDeps[CacheKey]; @@ -1014,7 +748,8 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize, for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end(); I != E; ++I) { DenseMap<BasicBlock*, Value*>::iterator VI = Visited.find(I->first); - if (VI == Visited.end() || VI->second == Pointer) continue; + if (VI == Visited.end() || VI->second == Pointer.getAddr()) + continue; // We have a pointer mismatch in a block. Just return clobber, saying // that something was clobbered in this result. We could also do a @@ -1025,7 +760,7 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize, for (NonLocalDepInfo::iterator I = Cache->begin(), E = Cache->end(); I != E; ++I) { - Visited.insert(std::make_pair(I->first, Pointer)); + Visited.insert(std::make_pair(I->first, Pointer.getAddr())); if (!I->second.isNonLocal()) Result.push_back(*I); } @@ -1065,8 +800,9 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize, // Get the dependency info for Pointer in BB. If we have cached // information, we will use it, otherwise we compute it. DEBUG(AssertSorted(*Cache, NumSortedEntries)); - MemDepResult Dep = GetNonLocalInfoForBlock(Pointer, PointeeSize, isLoad, - BB, Cache, NumSortedEntries); + MemDepResult Dep = GetNonLocalInfoForBlock(Pointer.getAddr(), PointeeSize, + isLoad, BB, Cache, + NumSortedEntries); // If we got a Def or Clobber, add this to the list of results. if (!Dep.isNonLocal()) { @@ -1077,18 +813,14 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize, // If 'Pointer' is an instruction defined in this block, then we need to do // phi translation to change it into a value live in the predecessor block. - // If phi translation fails, then we can't continue dependence analysis. - Instruction *PtrInst = dyn_cast<Instruction>(Pointer); - bool NeedsPHITranslation = PtrInst && PtrInst->getParent() == BB; - - // If no PHI translation is needed, just add all the predecessors of this - // block to scan them as well. - if (!NeedsPHITranslation) { + // If not, we just add the predecessors to the worklist and scan them with + // the same Pointer. + if (!Pointer.NeedsPHITranslationFromBlock(BB)) { SkipFirstBlock = false; for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) { // Verify that we haven't looked at this block yet. std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool> - InsertRes = Visited.insert(std::make_pair(*PI, Pointer)); + InsertRes = Visited.insert(std::make_pair(*PI, Pointer.getAddr())); if (InsertRes.second) { // First time we've looked at *PI. Worklist.push_back(*PI); @@ -1098,16 +830,17 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize, // If we have seen this block before, but it was with a different // pointer then we have a phi translation failure and we have to treat // this as a clobber. - if (InsertRes.first->second != Pointer) + if (InsertRes.first->second != Pointer.getAddr()) goto PredTranslationFailure; } continue; } - // If we do need to do phi translation, then there are a bunch of different - // cases, because we have to find a Value* live in the predecessor block. We - // know that PtrInst is defined in this block at least. - + // We do need to do phi translation, if we know ahead of time we can't phi + // translate this value, don't even try. + if (!Pointer.IsPotentiallyPHITranslatable()) + goto PredTranslationFailure; + // We may have added values to the cache list before this PHI translation. // If so, we haven't done anything to ensure that the cache remains sorted. // Sort it now (if needed) so that recursive invocations of @@ -1117,19 +850,17 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize, SortNonLocalDepInfoCache(*Cache, NumSortedEntries); NumSortedEntries = Cache->size(); } - - // If this is a computation derived from a PHI node, use the suitably - // translated incoming values for each pred as the phi translated version. - if (!isPHITranslatable(PtrInst)) - goto PredTranslationFailure; - Cache = 0; - + for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) { BasicBlock *Pred = *PI; - // Get the PHI translated pointer in this predecessor. This can fail and - // return null if not translatable. - Value *PredPtr = GetPHITranslatedValue(PtrInst, BB, Pred, TD); + + // Get the PHI translated pointer in this predecessor. This can fail if + // not translatable, in which case the getAddr() returns null. + PHITransAddr PredPointer(Pointer); + PredPointer.PHITranslateValue(BB, Pred); + + Value *PredPtrVal = PredPointer.getAddr(); // Check to see if we have already visited this pred block with another // pointer. If so, we can't do this lookup. This failure can occur @@ -1137,12 +868,12 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize, // the successor translates to a pointer value different than the // pointer the block was first analyzed with. std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool> - InsertRes = Visited.insert(std::make_pair(Pred, PredPtr)); + InsertRes = Visited.insert(std::make_pair(Pred, PredPtrVal)); if (!InsertRes.second) { // If the predecessor was visited with PredPtr, then we already did // the analysis and can ignore it. - if (InsertRes.first->second == PredPtr) + if (InsertRes.first->second == PredPtrVal) continue; // Otherwise, the block was previously analyzed with a different @@ -1155,7 +886,7 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize, // predecessor, then we have to assume that the pointer is clobbered in // that predecessor. We can still do PRE of the load, which would insert // a computation of the pointer in this predecessor. - if (PredPtr == 0) { + if (PredPtrVal == 0) { // Add the entry to the Result list. NonLocalDepEntry Entry(Pred, MemDepResult::getClobber(Pred->getTerminator())); @@ -1201,7 +932,7 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize, // If we have a problem phi translating, fall through to the code below // to handle the failure condition. - if (getNonLocalPointerDepFromBB(PredPtr, PointeeSize, isLoad, Pred, + if (getNonLocalPointerDepFromBB(PredPointer, PointeeSize, isLoad, Pred, Result, Visited)) goto PredTranslationFailure; } diff --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp index b703a76ba90..a283a4beece 100644 --- a/llvm/lib/Transforms/Scalar/GVN.cpp +++ b/llvm/lib/Transforms/Scalar/GVN.cpp @@ -36,6 +36,7 @@ #include "llvm/Analysis/Dominators.h" #include "llvm/Analysis/MemoryBuiltins.h" #include "llvm/Analysis/MemoryDependenceAnalysis.h" +#include "llvm/Analysis/PHITransAddr.h" #include "llvm/Support/CFG.h" #include "llvm/Support/CommandLine.h" #include "llvm/Support/Debug.h" @@ -1597,39 +1598,43 @@ bool GVN::processNonLocalLoad(LoadInst *LI, // Do PHI translation to get its value in the predecessor if necessary. The // returned pointer (if non-null) is guaranteed to dominate UnavailablePred. // - // FIXME: This may insert a computation, but we don't tell scalar GVN - // optimization stuff about it. How do we do this? SmallVector<Instruction*, 8> NewInsts; - Value *LoadPtr = 0; // If all preds have a single successor, then we know it is safe to insert the // load on the pred (?!?), so we can insert code to materialize the pointer if // it is not available. + PHITransAddr Address(LI->getOperand(0), TD); + Value *LoadPtr = 0; if (allSingleSucc) { - LoadPtr = MD->InsertPHITranslatedPointer(LI->getOperand(0), LoadBB, - UnavailablePred, TD, *DT,NewInsts); + LoadPtr = Address.PHITranslateWithInsertion(LoadBB, UnavailablePred, + *DT, NewInsts); } else { - LoadPtr = MD->GetAvailablePHITranslatedValue(LI->getOperand(0), LoadBB, - UnavailablePred, TD, *DT); + Address.PHITranslateValue(LoadBB, UnavailablePred); + LoadPtr = Address.getAddr(); + + // Make sure the value is live in the predecessor. + if (Instruction *Inst = dyn_cast_or_null<Instruction>(LoadPtr)) + if (!DT->dominates(Inst->getParent(), UnavailablePred)) + LoadPtr = 0; } - // Assign value numbers to these new instructions. - for (SmallVector<Instruction*, 8>::iterator NI = NewInsts.begin(), - NE = NewInsts.end(); NI != NE; ++NI) { - // FIXME: We really _ought_ to insert these value numbers into their - // parent's availability map. However, in doing so, we risk getting into - // ordering issues. If a block hasn't been processed yet, we would be - // marking a value as AVAIL-IN, which isn't what we intend. - VN.lookup_or_add(*NI); - } - // If we couldn't find or insert a computation of this phi translated value, // we fail PRE. if (LoadPtr == 0) { + assert(NewInsts.empty() && "Shouldn't insert insts on failure"); DEBUG(errs() << "COULDN'T INSERT PHI TRANSLATED VALUE OF: " << *LI->getOperand(0) << "\n"); return false; } + + // Assign value numbers to these new instructions. + for (unsigned i = 0, e = NewInsts.size(); i != e; ++i) { + // FIXME: We really _ought_ to insert these value numbers into their + // parent's availability map. However, in doing so, we risk getting into + // ordering issues. If a block hasn't been processed yet, we would be + // marking a value as AVAIL-IN, which isn't what we intend. + VN.lookup_or_add(NewInsts[i]); + } // Make sure it is valid to move this load here. We have to watch out for: // @1 = getelementptr (i8* p, ... diff --git a/llvm/test/Transforms/GVN/rle.ll b/llvm/test/Transforms/GVN/rle.ll index e667eece85d..0a2b9536040 100644 --- a/llvm/test/Transforms/GVN/rle.ll +++ b/llvm/test/Transforms/GVN/rle.ll @@ -388,6 +388,7 @@ declare i1 @cond() readonly declare i1 @cond2() readonly define i32 @phi_trans2() { +; CHECK: @phi_trans2 entry: %P = alloca i32, i32 400 br label %F1 @@ -411,9 +412,57 @@ F: br label %F1 TX: - ret i32 %x ;; SHOULD NOT BE COMPILED TO 'ret i32 42'. + ; This load should not be compiled to 'ret i32 42'. An overly clever + ; implementation of GVN would see that we're returning 17 if the loop + ; executes once or 42 if it executes more than that, but we'd have to do + ; loop restructuring to expose this, and GVN shouldn't do this sort of CFG + ; transformation. + +; CHECK: TX: +; CHECK: ret i32 %x + ret i32 %x TY: ret i32 0 } +define i32 @phi_trans3(i32* %p) { +; CHECK: @phi_trans3 +block1: + br i1 true, label %block2, label %block3 + +block2: + store i32 87, i32* %p + br label %block4 + +block3: + %p2 = getelementptr i32* %p, i32 43 + store i32 97, i32* %p2 + br label %block4 + +block4: + %A = phi i32 [-1, %block2], [42, %block3] + br i1 true, label %block5, label %exit + +; CHECK: block4: +; CHECK-NEXT: %D = phi i32 [ 87, %block2 ], [ 97, %block3 ] +; CHECK-NOT: load + +block5: + %B = add i32 %A, 1 + br i1 true, label %block6, label %exit + +block6: + %C = getelementptr i32* %p, i32 %B + br i1 true, label %block7, label %exit + +block7: + %D = load i32* %C + ret i32 %D + +; CHECK: block7: +; CHECK-NEXT: ret i32 %D + +exit: + ret i32 -1 +} |
