diff options
author | rdivacky <rdivacky@FreeBSD.org> | 2009-12-01 11:07:05 +0000 |
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committer | rdivacky <rdivacky@FreeBSD.org> | 2009-12-01 11:07:05 +0000 |
commit | e7908924d847e63b02bc82bfaa1709ab9c774dcd (patch) | |
tree | ffe0478472eaa0686f11cb02c6df7d257b8719b0 /lib/Analysis/MemoryDependenceAnalysis.cpp | |
parent | bf68f1ea49e39c4194f339ddd4421b0c3a31988b (diff) | |
download | FreeBSD-src-e7908924d847e63b02bc82bfaa1709ab9c774dcd.zip FreeBSD-src-e7908924d847e63b02bc82bfaa1709ab9c774dcd.tar.gz |
Update LLVM to r90226.
Diffstat (limited to 'lib/Analysis/MemoryDependenceAnalysis.cpp')
-rw-r--r-- | lib/Analysis/MemoryDependenceAnalysis.cpp | 464 |
1 files changed, 396 insertions, 68 deletions
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp index 0ec0e74..ae6f970 100644 --- a/lib/Analysis/MemoryDependenceAnalysis.cpp +++ b/lib/Analysis/MemoryDependenceAnalysis.cpp @@ -20,6 +20,8 @@ #include "llvm/IntrinsicInst.h" #include "llvm/Function.h" #include "llvm/Analysis/AliasAnalysis.h" +#include "llvm/Analysis/Dominators.h" +#include "llvm/Analysis/InstructionSimplify.h" #include "llvm/Analysis/MemoryBuiltins.h" #include "llvm/ADT/Statistic.h" #include "llvm/ADT/STLExtras.h" @@ -117,10 +119,6 @@ getCallSiteDependencyFrom(CallSite CS, bool isReadOnlyCall, Pointer = Inst->getOperand(1); // calls to free() erase the entire structure PointerSize = ~0ULL; - } else if (isFreeCall(Inst)) { - Pointer = Inst->getOperand(0); - // calls to free() erase the entire structure - PointerSize = ~0ULL; } else if (isa<CallInst>(Inst) || isa<InvokeInst>(Inst)) { // Debug intrinsics don't cause dependences. if (isa<DbgInfoIntrinsic>(Inst)) continue; @@ -174,7 +172,7 @@ MemDepResult MemoryDependenceAnalysis:: getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad, BasicBlock::iterator ScanIt, BasicBlock *BB) { - Value* invariantTag = 0; + Value *invariantTag = 0; // Walk backwards through the basic block, looking for dependencies. while (ScanIt != BB->begin()) { @@ -185,12 +183,12 @@ getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad, if (invariantTag == Inst) { invariantTag = 0; continue; - } else if (IntrinsicInst* II = dyn_cast<IntrinsicInst>(Inst)) { + } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst)) { // If we pass an invariant-end marker, then we've just entered an // invariant region and can start ignoring dependencies. if (II->getIntrinsicID() == Intrinsic::invariant_end) { uint64_t invariantSize = ~0ULL; - if (ConstantInt* CI = dyn_cast<ConstantInt>(II->getOperand(2))) + if (ConstantInt *CI = dyn_cast<ConstantInt>(II->getOperand(2))) invariantSize = CI->getZExtValue(); AliasAnalysis::AliasResult R = @@ -203,9 +201,9 @@ getPointerDependencyFrom(Value *MemPtr, uint64_t MemSize, bool isLoad, // If we reach a lifetime begin or end marker, then the query ends here // because the value is undefined. } else if (II->getIntrinsicID() == Intrinsic::lifetime_start || - II->getIntrinsicID() == Intrinsic::lifetime_end) { + II->getIntrinsicID() == Intrinsic::lifetime_end) { uint64_t invariantSize = ~0ULL; - if (ConstantInt* CI = dyn_cast<ConstantInt>(II->getOperand(1))) + if (ConstantInt *CI = dyn_cast<ConstantInt>(II->getOperand(1))) invariantSize = CI->getZExtValue(); AliasAnalysis::AliasResult R = @@ -371,20 +369,41 @@ MemDepResult MemoryDependenceAnalysis::getDependency(Instruction *QueryInst) { // calls to free() erase the entire structure, not just a field. MemSize = ~0UL; } else if (isa<CallInst>(QueryInst) || isa<InvokeInst>(QueryInst)) { - CallSite QueryCS = CallSite::get(QueryInst); - bool isReadOnly = AA->onlyReadsMemory(QueryCS); - LocalCache = getCallSiteDependencyFrom(QueryCS, isReadOnly, ScanPos, - QueryParent); + int IntrinsicID = 0; // Intrinsic IDs start at 1. + if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(QueryInst)) + IntrinsicID = II->getIntrinsicID(); + + switch (IntrinsicID) { + case Intrinsic::lifetime_start: + case Intrinsic::lifetime_end: + case Intrinsic::invariant_start: + MemPtr = QueryInst->getOperand(2); + MemSize = cast<ConstantInt>(QueryInst->getOperand(1))->getZExtValue(); + break; + case Intrinsic::invariant_end: + MemPtr = QueryInst->getOperand(3); + MemSize = cast<ConstantInt>(QueryInst->getOperand(2))->getZExtValue(); + break; + default: + CallSite QueryCS = CallSite::get(QueryInst); + bool isReadOnly = AA->onlyReadsMemory(QueryCS); + LocalCache = getCallSiteDependencyFrom(QueryCS, isReadOnly, ScanPos, + QueryParent); + } } else { // Non-memory instruction. LocalCache = MemDepResult::getClobber(--BasicBlock::iterator(ScanPos)); } // If we need to do a pointer scan, make it happen. - if (MemPtr) - LocalCache = getPointerDependencyFrom(MemPtr, MemSize, - isa<LoadInst>(QueryInst), - ScanPos, QueryParent); + if (MemPtr) { + bool isLoad = !QueryInst->mayWriteToMemory(); + if (IntrinsicInst *II = dyn_cast<MemoryUseIntrinsic>(QueryInst)) { + isLoad |= II->getIntrinsicID() == Intrinsic::lifetime_end; + } + LocalCache = getPointerDependencyFrom(MemPtr, MemSize, isLoad, ScanPos, + QueryParent); + } // Remember the result! if (Instruction *I = LocalCache.getInst()) @@ -688,6 +707,274 @@ 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 @@ -831,66 +1118,107 @@ getNonLocalPointerDepFromBB(Value *Pointer, uint64_t PointeeSize, NumSortedEntries = Cache->size(); } - // If this is directly a PHI node, just use the incoming values for each - // pred as the phi translated version. - if (PHINode *PtrPHI = dyn_cast<PHINode>(PtrInst)) { - Cache = 0; - - for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) { - BasicBlock *Pred = *PI; - Value *PredPtr = PtrPHI->getIncomingValueForBlock(Pred); - - // 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 - // with PHI translation when a critical edge exists and the PHI node in - // 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)); + // 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; - 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) - continue; - - // Otherwise, the block was previously analyzed with a different - // pointer. We can't represent the result of this case, so we just - // treat this as a phi translation failure. - 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); + + // 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 + // with PHI translation when a critical edge exists and the PHI node in + // 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)); - // FIXME: it is entirely possible that PHI translating will end up with - // the same value. Consider PHI translating something like: - // X = phi [x, bb1], [y, bb2]. PHI translating for bb1 doesn't *need* - // to recurse here, pedantically speaking. + 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) + continue; - // If we have a problem phi translating, fall through to the code below - // to handle the failure condition. - if (getNonLocalPointerDepFromBB(PredPtr, PointeeSize, isLoad, Pred, - Result, Visited)) - goto PredTranslationFailure; + // Otherwise, the block was previously analyzed with a different + // pointer. We can't represent the result of this case, so we just + // treat this as a phi translation failure. + goto PredTranslationFailure; } - // Refresh the CacheInfo/Cache pointer so that it isn't invalidated. - CacheInfo = &NonLocalPointerDeps[CacheKey]; - Cache = &CacheInfo->second; - NumSortedEntries = Cache->size(); + // If PHI translation was unable to find an available pointer in this + // 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) { + // Add the entry to the Result list. + NonLocalDepEntry Entry(Pred, + MemDepResult::getClobber(Pred->getTerminator())); + Result.push_back(Entry); + + // Add it to the cache for this CacheKey so that subsequent queries get + // this result. + Cache = &NonLocalPointerDeps[CacheKey].second; + MemoryDependenceAnalysis::NonLocalDepInfo::iterator It = + std::upper_bound(Cache->begin(), Cache->end(), Entry); + + if (It != Cache->begin() && prior(It)->first == Pred) + --It; + + if (It == Cache->end() || It->first != Pred) { + Cache->insert(It, Entry); + // Add it to the reverse map. + ReverseNonLocalPtrDeps[Pred->getTerminator()].insert(CacheKey); + } else if (!It->second.isDirty()) { + // noop + } else if (It->second.getInst() == Pred->getTerminator()) { + // Same instruction, clear the dirty marker. + It->second = Entry.second; + } else if (It->second.getInst() == 0) { + // Dirty, with no instruction, just add this. + It->second = Entry.second; + ReverseNonLocalPtrDeps[Pred->getTerminator()].insert(CacheKey); + } else { + // Otherwise, dirty with a different instruction. + RemoveFromReverseMap(ReverseNonLocalPtrDeps, It->second.getInst(), + CacheKey); + It->second = Entry.second; + ReverseNonLocalPtrDeps[Pred->getTerminator()].insert(CacheKey); + } + Cache = 0; + continue; + } + + // FIXME: it is entirely possible that PHI translating will end up with + // the same value. Consider PHI translating something like: + // X = phi [x, bb1], [y, bb2]. PHI translating for bb1 doesn't *need* + // to recurse here, pedantically speaking. - // Since we did phi translation, the "Cache" set won't contain all of the - // results for the query. This is ok (we can still use it to accelerate - // specific block queries) but we can't do the fastpath "return all - // results from the set" Clear out the indicator for this. - CacheInfo->first = BBSkipFirstBlockPair(); - SkipFirstBlock = false; - continue; + // If we have a problem phi translating, fall through to the code below + // to handle the failure condition. + if (getNonLocalPointerDepFromBB(PredPtr, PointeeSize, isLoad, Pred, + Result, Visited)) + goto PredTranslationFailure; } - // TODO: BITCAST, GEP. + // Refresh the CacheInfo/Cache pointer so that it isn't invalidated. + CacheInfo = &NonLocalPointerDeps[CacheKey]; + Cache = &CacheInfo->second; + NumSortedEntries = Cache->size(); - // cerr << "MEMDEP: Could not PHI translate: " << *Pointer; - // if (isa<BitCastInst>(PtrInst) || isa<GetElementPtrInst>(PtrInst)) - // cerr << "OP:\t\t\t\t" << *PtrInst->getOperand(0); + // Since we did phi translation, the "Cache" set won't contain all of the + // results for the query. This is ok (we can still use it to accelerate + // specific block queries) but we can't do the fastpath "return all + // results from the set" Clear out the indicator for this. + CacheInfo->first = BBSkipFirstBlockPair(); + SkipFirstBlock = false; + continue; + PredTranslationFailure: if (Cache == 0) { |