X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FLazyValueInfo.cpp;h=9f919f7644a3fa62b0951b82a5639476e45218f8;hb=846781235d0c027702e2c528a6660ec14ca8edcd;hp=83e021295bad041f293863d96a0e0093854b7eee;hpb=97f87abbf4bc270c794abbbf8e152f38b0731d85;p=oota-llvm.git diff --git a/lib/Analysis/LazyValueInfo.cpp b/lib/Analysis/LazyValueInfo.cpp index 83e021295ba..9f919f7644a 100644 --- a/lib/Analysis/LazyValueInfo.cpp +++ b/lib/Analysis/LazyValueInfo.cpp @@ -12,28 +12,29 @@ // //===----------------------------------------------------------------------===// -#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/IntrinsicInst.h" +#include "llvm/ADT/DenseSet.h" +#include "llvm/ADT/STLExtras.h" #include "llvm/Analysis/ConstantFolding.h" -#include "llvm/Target/TargetData.h" -#include "llvm/Target/TargetLibraryInfo.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/PatternMatch.h" #include "llvm/Support/raw_ostream.h" -#include "llvm/Support/ValueHandle.h" -#include "llvm/ADT/DenseSet.h" -#include "llvm/ADT/STLExtras.h" +#include "llvm/Target/TargetLibraryInfo.h" #include #include using namespace llvm; using namespace PatternMatch; +#define DEBUG_TYPE "lazy-value-info" + char LazyValueInfo::ID = 0; INITIALIZE_PASS_BEGIN(LazyValueInfo, "lazy-value-info", "Lazy Value Information Analysis", false, true) @@ -82,7 +83,7 @@ class LVILatticeVal { ConstantRange Range; public: - LVILatticeVal() : Tag(undefined), Val(0), Range(1, true) {} + LVILatticeVal() : Tag(undefined), Val(nullptr), Range(1, true) {} static LVILatticeVal get(Constant *C) { LVILatticeVal Res; @@ -172,7 +173,7 @@ public: if (NewR.isEmptySet()) return markOverdefined(); - bool changed = Range == NewR; + bool changed = Range != NewR; Range = NewR; return changed; } @@ -212,7 +213,7 @@ public: // Unless we can prove that the two Constants are different, we must // move to overdefined. - // FIXME: use TargetData/TargetLibraryInfo for smarter constant folding. + // FIXME: use DataLayout/TargetLibraryInfo for smarter constant folding. if (ConstantInt *Res = dyn_cast( ConstantFoldCompareInstOperands(CmpInst::ICMP_NE, getConstant(), @@ -238,7 +239,7 @@ public: // Unless we can prove that the two Constants are different, we must // move to overdefined. - // FIXME: use TargetData/TargetLibraryInfo for smarter constant folding. + // FIXME: use DataLayout/TargetLibraryInfo for smarter constant folding. if (ConstantInt *Res = dyn_cast( ConstantFoldCompareInstOperands(CmpInst::ICMP_NE, getNotConstant(), @@ -294,7 +295,7 @@ 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 { @@ -302,9 +303,9 @@ namespace { LVIValueHandle(Value *V, LazyValueInfoCache *P) : CallbackVH(V), Parent(P) { } - - void deleted(); - void allUsesReplacedWith(Value *V) { + + void deleted() override; + void allUsesReplacedWith(Value *V) override { deleted(); } }; @@ -421,8 +422,8 @@ 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); @@ -444,8 +445,8 @@ void LazyValueInfoCache::eraseBlock(BasicBlock *BB) { 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); @@ -457,8 +458,10 @@ 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(); + } } } @@ -468,8 +471,10 @@ 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) { @@ -512,7 +517,7 @@ bool LazyValueInfoCache::solveBlockValue(Value *Val, BasicBlock *BB) { BBLV.markOverdefined(); Instruction *BBI = dyn_cast(Val); - if (BBI == 0 || BBI->getParent() != BB) { + if (!BBI || BBI->getParent() != BB) { return ODCacheUpdater.markResult(solveBlockValueNonLocal(BBLV, Val, BB)); } @@ -553,13 +558,11 @@ 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; @@ -569,11 +572,11 @@ static bool InstructionDereferencesPointer(Instruction *I, Value *Ptr) { if (!Len || Len->isZero()) return false; if (MI->getDestAddressSpace() == 0) - if (MI->getRawDest() == Ptr || MI->getDest() == Ptr) + if (GetUnderlyingObject(MI->getRawDest()) == Ptr) return true; if (MemTransferInst *MTI = dyn_cast(MI)) if (MTI->getSourceAddressSpace() == 0) - if (MTI->getRawSource() == Ptr || MTI->getSource() == Ptr) + if (GetUnderlyingObject(MTI->getRawSource()) == Ptr) return true; } return false; @@ -587,13 +590,19 @@ bool LazyValueInfoCache::solveBlockValueNonLocal(LVILatticeVal &BBLV, // then we know that the pointer can't be NULL. bool NotNull = false; if (Val->getType()->isPointerTy()) { - if (isa(Val)) { + if (isKnownNonNull(Val)) { NotNull = true; } else { - for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();BI != BE;++BI){ - if (InstructionDereferencesPointer(BI, Val)) { - NotNull = true; - break; + Value *UnderlyingVal = GetUnderlyingObject(Val); + // If 'GetUnderlyingObject' didn't converge, skip it. It won't converge + // inside InstructionDereferencesPointer either. + if (UnderlyingVal == GetUnderlyingObject(UnderlyingVal, nullptr, 1)) { + for (BasicBlock::iterator BI = BB->begin(), BE = BB->end(); + BI != BE; ++BI) { + if (InstructionDereferencesPointer(BI, UnderlyingVal)) { + NotNull = true; + break; + } } } } @@ -766,15 +775,10 @@ 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())) { @@ -810,7 +814,7 @@ bool LazyValueInfoCache::getEdgeValue(Value *Val, BasicBlock *BBFrom, // Recognize the range checking idiom that InstCombine produces. // (X-C1) u< C2 --> [C1, C1+C2) - ConstantInt *NegOffset = 0; + ConstantInt *NegOffset = nullptr; if (ICI->getPredicate() == ICmpInst::ICMP_ULT) match(ICI->getOperand(0), m_Add(m_Specific(Val), m_ConstantInt(NegOffset))); @@ -827,25 +831,8 @@ bool LazyValueInfoCache::getEdgeValue(Value *Val, BasicBlock *BBFrom, // 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; } } @@ -855,40 +842,74 @@ 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 (SwitchInst::CaseIt i = SI->case_begin(), e = SI->case_end(); - i != e; ++i) { - if (i.getCaseSuccessor() != BBTo) continue; - if (NumEdges++) break; - EdgeVal = i.getCaseValue(); - } - 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"); @@ -993,7 +1014,8 @@ bool LazyValueInfo::runOnFunction(Function &F) { if (PImpl) getCache(PImpl).clear(); - TD = getAnalysisIfAvailable(); + DataLayoutPass *DLP = getAnalysisIfAvailable(); + DL = DLP ? &DLP->getDataLayout() : nullptr; TLI = &getAnalysis(); // Fully lazy. @@ -1009,7 +1031,7 @@ void LazyValueInfo::releaseMemory() { // If the cache was allocated, free it. if (PImpl) { delete &getCache(PImpl); - PImpl = 0; + PImpl = nullptr; } } @@ -1023,7 +1045,7 @@ Constant *LazyValueInfo::getConstant(Value *V, BasicBlock *BB) { if (const APInt *SingleVal = CR.getSingleElement()) return ConstantInt::get(V->getContext(), *SingleVal); } - return 0; + return nullptr; } /// getConstantOnEdge - Determine whether the specified value is known to be a @@ -1039,7 +1061,7 @@ Constant *LazyValueInfo::getConstantOnEdge(Value *V, BasicBlock *FromBB, if (const APInt *SingleVal = CR.getSingleElement()) return ConstantInt::get(V->getContext(), *SingleVal); } - return 0; + return nullptr; } /// getPredicateOnEdge - Determine whether the specified value comparison @@ -1051,9 +1073,9 @@ LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C, LVILatticeVal Result = getCache(PImpl).getValueOnEdge(V, FromBB, ToBB); // If we know the value is a constant, evaluate the conditional. - Constant *Res = 0; + Constant *Res = nullptr; 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; @@ -1095,14 +1117,14 @@ 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;