X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FLazyValueInfo.cpp;h=e42d0eee31354eba7a463c59b9ef085caaf3e52e;hb=19d764fb05662ff6b423cf6dc97d300276e4b586;hp=9be106b8575291e1b03d3d9f8a02278503b2525c;hpb=e68713ae8b7bc30ce96f9d74685e3c230340a01f;p=oota-llvm.git diff --git a/lib/Analysis/LazyValueInfo.cpp b/lib/Analysis/LazyValueInfo.cpp index 9be106b8575..e42d0eee313 100644 --- a/lib/Analysis/LazyValueInfo.cpp +++ b/lib/Analysis/LazyValueInfo.cpp @@ -14,26 +14,31 @@ #define DEBUG_TYPE "lazy-value-info" #include "llvm/Analysis/LazyValueInfo.h" -#include "llvm/Analysis/ValueTracking.h" -#include "llvm/Constants.h" -#include "llvm/Instructions.h" +#include "llvm/ADT/DenseSet.h" +#include "llvm/ADT/STLExtras.h" #include "llvm/Analysis/ConstantFolding.h" -#include "llvm/Target/TargetData.h" -#include "llvm/Support/CFG.h" -#include "llvm/Support/ConstantRange.h" +#include "llvm/Analysis/ValueTracking.h" +#include "llvm/IR/CFG.h" +#include "llvm/IR/ConstantRange.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/Instructions.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/PatternMatch.h" +#include "llvm/IR/ValueHandle.h" #include "llvm/Support/Debug.h" #include "llvm/Support/raw_ostream.h" -#include "llvm/Support/ValueHandle.h" -#include "llvm/ADT/DenseMap.h" -#include "llvm/ADT/DenseSet.h" -#include "llvm/ADT/STLExtras.h" +#include "llvm/Target/TargetLibraryInfo.h" #include -#include #include using namespace llvm; +using namespace PatternMatch; char LazyValueInfo::ID = 0; -INITIALIZE_PASS(LazyValueInfo, "lazy-value-info", +INITIALIZE_PASS_BEGIN(LazyValueInfo, "lazy-value-info", + "Lazy Value Information Analysis", false, true) +INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfo) +INITIALIZE_PASS_END(LazyValueInfo, "lazy-value-info", "Lazy Value Information Analysis", false, true) namespace llvm { @@ -61,10 +66,10 @@ class LVILatticeVal { constant, /// notconstant - This Value is known to not have the specified value. notconstant, - + /// constantrange - The Value falls within this range. constantrange, - + /// overdefined - This value is not known to be constant, and we know that /// it has a value. overdefined @@ -167,7 +172,7 @@ public: if (NewR.isEmptySet()) return markOverdefined(); - bool changed = Range == NewR; + bool changed = Range != NewR; Range = NewR; return changed; } @@ -207,7 +212,7 @@ public: // Unless we can prove that the two Constants are different, we must // move to overdefined. - // FIXME: use TargetData for smarter constant folding. + // FIXME: use DataLayout/TargetLibraryInfo for smarter constant folding. if (ConstantInt *Res = dyn_cast( ConstantFoldCompareInstOperands(CmpInst::ICMP_NE, getConstant(), @@ -233,7 +238,7 @@ public: // Unless we can prove that the two Constants are different, we must // move to overdefined. - // FIXME: use TargetData for smarter constant folding. + // FIXME: use DataLayout/TargetLibraryInfo for smarter constant folding. if (ConstantInt *Res = dyn_cast( ConstantFoldCompareInstOperands(CmpInst::ICMP_NE, getNotConstant(), @@ -267,6 +272,8 @@ public: } // end anonymous namespace. namespace llvm { +raw_ostream &operator<<(raw_ostream &OS, const LVILatticeVal &Val) + LLVM_ATTRIBUTE_USED; raw_ostream &operator<<(raw_ostream &OS, const LVILatticeVal &Val) { if (Val.isUndefined()) return OS << "undefined"; @@ -287,7 +294,7 @@ raw_ostream &operator<<(raw_ostream &OS, const LVILatticeVal &Val) { //===----------------------------------------------------------------------===// namespace { - /// LVIValueHandle - A callback value handle update the cache when + /// LVIValueHandle - A callback value handle updates the cache when /// values are erased. class LazyValueInfoCache; struct LVIValueHandle : public CallbackVH { @@ -303,50 +310,6 @@ namespace { }; } -namespace llvm { - template<> - struct DenseMapInfo { - typedef DenseMapInfo PointerInfo; - static inline LVIValueHandle getEmptyKey() { - return LVIValueHandle(PointerInfo::getEmptyKey(), - static_cast(0)); - } - static inline LVIValueHandle getTombstoneKey() { - return LVIValueHandle(PointerInfo::getTombstoneKey(), - static_cast(0)); - } - static unsigned getHashValue(const LVIValueHandle &Val) { - return PointerInfo::getHashValue(Val); - } - static bool isEqual(const LVIValueHandle &LHS, const LVIValueHandle &RHS) { - return LHS == RHS; - } - }; - - template<> - struct DenseMapInfo, Value*> > { - typedef std::pair, Value*> PairTy; - typedef DenseMapInfo > APointerInfo; - typedef DenseMapInfo BPointerInfo; - static inline PairTy getEmptyKey() { - return std::make_pair(APointerInfo::getEmptyKey(), - BPointerInfo::getEmptyKey()); - } - static inline PairTy getTombstoneKey() { - return std::make_pair(APointerInfo::getTombstoneKey(), - BPointerInfo::getTombstoneKey()); - } - static unsigned getHashValue( const PairTy &Val) { - return APointerInfo::getHashValue(Val.first) ^ - BPointerInfo::getHashValue(Val.second); - } - static bool isEqual(const PairTy &LHS, const PairTy &RHS) { - return APointerInfo::isEqual(LHS.first, RHS.first) && - BPointerInfo::isEqual(LHS.second, RHS.second); - } - }; -} - namespace { /// LazyValueInfoCache - This is the cache kept by LazyValueInfo which /// maintains information about queries across the clients' queries. @@ -358,14 +321,18 @@ namespace { /// ValueCache - This is all of the cached information for all values, /// mapped from Value* to key information. - DenseMap ValueCache; + std::map ValueCache; /// OverDefinedCache - This tracks, on a per-block basis, the set of /// values that are over-defined at the end of that block. This is required /// for cache updating. typedef std::pair, Value*> OverDefinedPairTy; DenseSet OverDefinedCache; - + + /// SeenBlocks - Keep track of all blocks that we have ever seen, so we + /// don't spend time removing unused blocks from our caches. + DenseSet > SeenBlocks; + /// BlockValueStack - This stack holds the state of the value solver /// during a query. It basically emulates the callstack of the naive /// recursive value lookup process. @@ -436,6 +403,7 @@ namespace { /// clear - Empty the cache. void clear() { + SeenBlocks.clear(); ValueCache.clear(); OverDefinedCache.clear(); } @@ -453,8 +421,8 @@ void LVIValueHandle::deleted() { if (I->second == getValPtr()) ToErase.push_back(*I); } - - for (SmallVector::iterator I = ToErase.begin(), + + for (SmallVectorImpl::iterator I = ToErase.begin(), E = ToErase.end(); I != E; ++I) Parent->OverDefinedCache.erase(*I); @@ -464,18 +432,24 @@ void LVIValueHandle::deleted() { } void LazyValueInfoCache::eraseBlock(BasicBlock *BB) { + // Shortcut if we have never seen this block. + DenseSet >::iterator I = SeenBlocks.find(BB); + if (I == SeenBlocks.end()) + return; + SeenBlocks.erase(I); + SmallVector ToErase; for (DenseSet::iterator I = OverDefinedCache.begin(), E = OverDefinedCache.end(); I != E; ++I) { if (I->first == BB) ToErase.push_back(*I); } - - for (SmallVector::iterator I = ToErase.begin(), + + for (SmallVectorImpl::iterator I = ToErase.begin(), E = ToErase.end(); I != E; ++I) OverDefinedCache.erase(*I); - for (DenseMap::iterator + for (std::map::iterator I = ValueCache.begin(), E = ValueCache.end(); I != E; ++I) I->second.erase(BB); } @@ -483,8 +457,10 @@ void LazyValueInfoCache::eraseBlock(BasicBlock *BB) { void LazyValueInfoCache::solve() { while (!BlockValueStack.empty()) { std::pair &e = BlockValueStack.top(); - if (solveBlockValue(e.second, e.first)) + if (solveBlockValue(e.second, e.first)) { + assert(BlockValueStack.top() == e); BlockValueStack.pop(); + } } } @@ -494,8 +470,10 @@ bool LazyValueInfoCache::hasBlockValue(Value *Val, BasicBlock *BB) { return true; LVIValueHandle ValHandle(Val, this); - if (!ValueCache.count(ValHandle)) return false; - return ValueCache[ValHandle].count(BB); + std::map::iterator I = + ValueCache.find(ValHandle); + if (I == ValueCache.end()) return false; + return I->second.count(BB); } LVILatticeVal LazyValueInfoCache::getBlockValue(Value *Val, BasicBlock *BB) { @@ -503,6 +481,7 @@ LVILatticeVal LazyValueInfoCache::getBlockValue(Value *Val, BasicBlock *BB) { if (Constant *VC = dyn_cast(Val)) return LVILatticeVal::get(VC); + SeenBlocks.insert(BB); return lookup(Val)[BB]; } @@ -511,6 +490,7 @@ bool LazyValueInfoCache::solveBlockValue(Value *Val, BasicBlock *BB) { return true; ValueCacheEntryTy &Cache = lookup(Val); + SeenBlocks.insert(BB); LVILatticeVal &BBLV = Cache[BB]; // OverDefinedCacheUpdater is a helper object that will update @@ -544,6 +524,11 @@ bool LazyValueInfoCache::solveBlockValue(Value *Val, BasicBlock *BB) { return ODCacheUpdater.markResult(solveBlockValuePHINode(BBLV, PN, BB)); } + if (AllocaInst *AI = dyn_cast(BBI)) { + BBLV = LVILatticeVal::getNot(ConstantPointerNull::get(AI->getType())); + return ODCacheUpdater.markResult(true); + } + // We can only analyze the definitions of certain classes of instructions // (integral binops and casts at the moment), so bail if this isn't one. LVILatticeVal Result; @@ -572,15 +557,27 @@ bool LazyValueInfoCache::solveBlockValue(Value *Val, BasicBlock *BB) { static bool InstructionDereferencesPointer(Instruction *I, Value *Ptr) { if (LoadInst *L = dyn_cast(I)) { return L->getPointerAddressSpace() == 0 && - GetUnderlyingObject(L->getPointerOperand()) == - GetUnderlyingObject(Ptr); + GetUnderlyingObject(L->getPointerOperand()) == Ptr; } if (StoreInst *S = dyn_cast(I)) { return S->getPointerAddressSpace() == 0 && - GetUnderlyingObject(S->getPointerOperand()) == - GetUnderlyingObject(Ptr); + GetUnderlyingObject(S->getPointerOperand()) == Ptr; + } + if (MemIntrinsic *MI = dyn_cast(I)) { + if (MI->isVolatile()) return false; + + // FIXME: check whether it has a valuerange that excludes zero? + ConstantInt *Len = dyn_cast(MI->getLength()); + if (!Len || Len->isZero()) return false; + + if (MI->getDestAddressSpace() == 0) + if (GetUnderlyingObject(MI->getRawDest()) == Ptr) + return true; + if (MemTransferInst *MTI = dyn_cast(MI)) + if (MTI->getSourceAddressSpace() == 0) + if (GetUnderlyingObject(MTI->getRawSource()) == Ptr) + return true; } - // FIXME: llvm.memset, etc. return false; } @@ -592,10 +589,20 @@ bool LazyValueInfoCache::solveBlockValueNonLocal(LVILatticeVal &BBLV, // then we know that the pointer can't be NULL. bool NotNull = false; if (Val->getType()->isPointerTy()) { - for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();BI != BE;++BI){ - if (InstructionDereferencesPointer(BI, Val)) { - NotNull = true; - break; + if (isKnownNonNull(Val)) { + NotNull = true; + } else { + Value *UnderlyingVal = GetUnderlyingObject(Val); + // If 'GetUnderlyingObject' didn't converge, skip it. It won't converge + // inside InstructionDereferencesPointer either. + if (UnderlyingVal == GetUnderlyingObject(UnderlyingVal, NULL, 1)) { + for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); + BI != BE; ++BI) { + if (InstructionDereferencesPointer(BI, UnderlyingVal)) { + NotNull = true; + break; + } + } } } } @@ -605,7 +612,7 @@ bool LazyValueInfoCache::solveBlockValueNonLocal(LVILatticeVal &BBLV, if (BB == &BB->getParent()->getEntryBlock()) { assert(isa(Val) && "Unknown live-in to the entry block"); if (NotNull) { - const PointerType *PTy = cast(Val->getType()); + PointerType *PTy = cast(Val->getType()); Result = LVILatticeVal::getNot(ConstantPointerNull::get(PTy)); } else { Result.markOverdefined(); @@ -633,7 +640,7 @@ bool LazyValueInfoCache::solveBlockValueNonLocal(LVILatticeVal &BBLV, // If we previously determined that this is a pointer that can't be null // then return that rather than giving up entirely. if (NotNull) { - const PointerType *PTy = cast(Val->getType()); + PointerType *PTy = cast(Val->getType()); Result = LVILatticeVal::getNot(ConstantPointerNull::get(PTy)); } @@ -703,7 +710,7 @@ bool LazyValueInfoCache::solveBlockValueConstantRange(LVILatticeVal &BBLV, ConstantRange LHSRange = LHSVal.getConstantRange(); ConstantRange RHSRange(1); - const IntegerType *ResultTy = cast(BBI->getType()); + IntegerType *ResultTy = cast(BBI->getType()); if (isa(BBI)) { if (ConstantInt *RHS = dyn_cast(BBI->getOperand(1))) { RHSRange = ConstantRange(RHS->getValue()); @@ -767,15 +774,10 @@ bool LazyValueInfoCache::solveBlockValueConstantRange(LVILatticeVal &BBLV, return true; } -/// getEdgeValue - This method attempts to infer more complex -bool LazyValueInfoCache::getEdgeValue(Value *Val, BasicBlock *BBFrom, - BasicBlock *BBTo, LVILatticeVal &Result) { - // If already a constant, there is nothing to compute. - if (Constant *VC = dyn_cast(Val)) { - Result = LVILatticeVal::get(VC); - return true; - } - +/// \brief Compute the value of Val on the edge BBFrom -> BBTo. Returns false if +/// Val is not constrained on the edge. +static bool getEdgeValueLocal(Value *Val, BasicBlock *BBFrom, + BasicBlock *BBTo, LVILatticeVal &Result) { // TODO: Handle more complex conditionals. If (v == 0 || v2 < 1) is false, we // know that v != 0. if (BranchInst *BI = dyn_cast(BBFrom->getTerminator())) { @@ -798,9 +800,8 @@ bool LazyValueInfoCache::getEdgeValue(Value *Val, BasicBlock *BBFrom, // If the condition of the branch is an equality comparison, we may be // able to infer the value. ICmpInst *ICI = dyn_cast(BI->getCondition()); - if (ICI && ICI->getOperand(0) == Val && - isa(ICI->getOperand(1))) { - if (ICI->isEquality()) { + if (ICI && isa(ICI->getOperand(1))) { + if (ICI->isEquality() && ICI->getOperand(0) == Val) { // We know that V has the RHS constant if this is a true SETEQ or // false SETNE. if (isTrueDest == (ICI->getPredicate() == ICmpInst::ICMP_EQ)) @@ -810,33 +811,27 @@ bool LazyValueInfoCache::getEdgeValue(Value *Val, BasicBlock *BBFrom, return true; } - if (ConstantInt *CI = dyn_cast(ICI->getOperand(1))) { + // Recognize the range checking idiom that InstCombine produces. + // (X-C1) u< C2 --> [C1, C1+C2) + ConstantInt *NegOffset = 0; + if (ICI->getPredicate() == ICmpInst::ICMP_ULT) + match(ICI->getOperand(0), m_Add(m_Specific(Val), + m_ConstantInt(NegOffset))); + + ConstantInt *CI = dyn_cast(ICI->getOperand(1)); + if (CI && (ICI->getOperand(0) == Val || NegOffset)) { // Calculate the range of values that would satisfy the comparison. - ConstantRange CmpRange(CI->getValue(), CI->getValue()+1); + ConstantRange CmpRange(CI->getValue()); ConstantRange TrueValues = ConstantRange::makeICmpRegion(ICI->getPredicate(), CmpRange); + if (NegOffset) // Apply the offset from above. + TrueValues = TrueValues.subtract(NegOffset->getValue()); + // If we're interested in the false dest, invert the condition. if (!isTrueDest) TrueValues = TrueValues.inverse(); - - // Figure out the possible values of the query BEFORE this branch. - if (!hasBlockValue(Val, BBFrom)) { - BlockValueStack.push(std::make_pair(BBFrom, Val)); - return false; - } - - LVILatticeVal InBlock = getBlockValue(Val, BBFrom); - if (!InBlock.isConstantRange()) { - Result = LVILatticeVal::getRange(TrueValues); - return true; - } - - // Find all potential values that satisfy both the input and output - // conditions. - ConstantRange PossibleValues = - TrueValues.intersectWith(InBlock.getConstantRange()); - Result = LVILatticeVal::getRange(PossibleValues); + Result = LVILatticeVal::getRange(TrueValues); return true; } } @@ -846,39 +841,74 @@ bool LazyValueInfoCache::getEdgeValue(Value *Val, BasicBlock *BBFrom, // If the edge was formed by a switch on the value, then we may know exactly // what it is. if (SwitchInst *SI = dyn_cast(BBFrom->getTerminator())) { - if (SI->getCondition() == Val) { - // We don't know anything in the default case. - if (SI->getDefaultDest() == BBTo) { - Result.markOverdefined(); - return true; - } - - // We only know something if there is exactly one value that goes from - // BBFrom to BBTo. - unsigned NumEdges = 0; - ConstantInt *EdgeVal = 0; - for (unsigned i = 1, e = SI->getNumSuccessors(); i != e; ++i) { - if (SI->getSuccessor(i) != BBTo) continue; - if (NumEdges++) break; - EdgeVal = SI->getCaseValue(i); - } - assert(EdgeVal && "Missing successor?"); - if (NumEdges == 1) { - Result = LVILatticeVal::get(EdgeVal); - return true; - } + if (SI->getCondition() != Val) + return false; + + bool DefaultCase = SI->getDefaultDest() == BBTo; + unsigned BitWidth = Val->getType()->getIntegerBitWidth(); + ConstantRange EdgesVals(BitWidth, DefaultCase/*isFullSet*/); + + for (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end(); + i != e; ++i) { + ConstantRange EdgeVal(i.getCaseValue()->getValue()); + if (DefaultCase) { + // It is possible that the default destination is the destination of + // some cases. There is no need to perform difference for those cases. + if (i.getCaseSuccessor() != BBTo) + EdgesVals = EdgesVals.difference(EdgeVal); + } else if (i.getCaseSuccessor() == BBTo) + EdgesVals = EdgesVals.unionWith(EdgeVal); } - } - - // Otherwise see if the value is known in the block. - if (hasBlockValue(Val, BBFrom)) { - Result = getBlockValue(Val, BBFrom); + Result = LVILatticeVal::getRange(EdgesVals); return true; } - BlockValueStack.push(std::make_pair(BBFrom, Val)); return false; } +/// \brief Compute the value of Val on the edge BBFrom -> BBTo, or the value at +/// the basic block if the edge does not constraint Val. +bool LazyValueInfoCache::getEdgeValue(Value *Val, BasicBlock *BBFrom, + BasicBlock *BBTo, LVILatticeVal &Result) { + // If already a constant, there is nothing to compute. + if (Constant *VC = dyn_cast(Val)) { + Result = LVILatticeVal::get(VC); + return true; + } + + if (getEdgeValueLocal(Val, BBFrom, BBTo, Result)) { + if (!Result.isConstantRange() || + Result.getConstantRange().getSingleElement()) + return true; + + // FIXME: this check should be moved to the beginning of the function when + // LVI better supports recursive values. Even for the single value case, we + // can intersect to detect dead code (an empty range). + if (!hasBlockValue(Val, BBFrom)) { + BlockValueStack.push(std::make_pair(BBFrom, Val)); + return false; + } + + // Try to intersect ranges of the BB and the constraint on the edge. + LVILatticeVal InBlock = getBlockValue(Val, BBFrom); + if (!InBlock.isConstantRange()) + return true; + + ConstantRange Range = + Result.getConstantRange().intersectWith(InBlock.getConstantRange()); + Result = LVILatticeVal::getRange(Range); + return true; + } + + if (!hasBlockValue(Val, BBFrom)) { + BlockValueStack.push(std::make_pair(BBFrom, Val)); + return false; + } + + // if we couldn't compute the value on the edge, use the value from the BB + Result = getBlockValue(Val, BBFrom); + return true; +} + LVILatticeVal LazyValueInfoCache::getValueInBlock(Value *V, BasicBlock *BB) { DEBUG(dbgs() << "LVI Getting block end value " << *V << " at '" << BB->getName() << "'\n"); @@ -982,12 +1012,20 @@ static LazyValueInfoCache &getCache(void *&PImpl) { bool LazyValueInfo::runOnFunction(Function &F) { if (PImpl) getCache(PImpl).clear(); - - TD = getAnalysisIfAvailable(); + + DataLayoutPass *DLP = getAnalysisIfAvailable(); + DL = DLP ? &DLP->getDataLayout() : 0; + TLI = &getAnalysis(); + // Fully lazy. return false; } +void LazyValueInfo::getAnalysisUsage(AnalysisUsage &AU) const { + AU.setPreservesAll(); + AU.addRequired(); +} + void LazyValueInfo::releaseMemory() { // If the cache was allocated, free it. if (PImpl) { @@ -1036,7 +1074,8 @@ LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C, // If we know the value is a constant, evaluate the conditional. Constant *Res = 0; if (Result.isConstant()) { - Res = ConstantFoldCompareInstOperands(Pred, Result.getConstant(), C, TD); + Res = ConstantFoldCompareInstOperands(Pred, Result.getConstant(), C, DL, + TLI); if (ConstantInt *ResCI = dyn_cast(Res)) return ResCI->isZero() ? False : True; return Unknown; @@ -1077,13 +1116,15 @@ LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C, if (Pred == ICmpInst::ICMP_EQ) { // !C1 == C -> false iff C1 == C. Res = ConstantFoldCompareInstOperands(ICmpInst::ICMP_NE, - Result.getNotConstant(), C, TD); + Result.getNotConstant(), C, DL, + TLI); if (Res->isNullValue()) return False; } else if (Pred == ICmpInst::ICMP_NE) { // !C1 != C -> true iff C1 == C. Res = ConstantFoldCompareInstOperands(ICmpInst::ICMP_NE, - Result.getNotConstant(), C, TD); + Result.getNotConstant(), C, DL, + TLI); if (Res->isNullValue()) return True; }