X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FAnalysis%2FLazyValueInfo.cpp;h=281ff89bfe46f869a6ba4d654bf97f717c201c87;hb=78c0b35bf7e5d9093c94f811a7e8c72f0a6357df;hp=d6dd627ba3065611517fd02bca9a629611b35257;hpb=7e2c793a2b5c746344652b6579e958ee42fafdcc;p=oota-llvm.git diff --git a/lib/Analysis/LazyValueInfo.cpp b/lib/Analysis/LazyValueInfo.cpp index d6dd627ba30..281ff89bfe4 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; @@ -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); @@ -499,8 +500,23 @@ bool LazyValueInfoCache::solveBlockValue(Value *Val, BasicBlock *BB) { // cache needs updating, i.e. if we have solve a new value or not. OverDefinedCacheUpdater ODCacheUpdater(Val, BB, BBLV, this); - // If we've already computed this block's value, return it. - if (!BBLV.isUndefined()) { + // Once this BB is encountered, Val's value for this BB will not be Undefined + // any longer. When we encounter this BB again, if Val's value is Overdefined, + // we need to compute its value again. + // + // For example, considering this control flow, + // BB1->BB2, BB1->BB3, BB2->BB3, BB2->BB4 + // + // Suppose we have "icmp slt %v, 0" in BB1, and "icmp sgt %v, 0" in BB3. At + // the very beginning, when analyzing edge BB2->BB3, we don't know %v's value + // in BB2, and the data flow algorithm tries to compute BB2's predecessors, so + // then we know %v has negative value on edge BB1->BB2. And then we return to + // check BB2 again, and at this moment BB2 has Overdefined value for %v in + // BB2. So we should have to follow data flow propagation algorithm to get the + // value on edge BB1->BB2 propagated to BB2, and finally %v on BB2 has a + // constant range describing a negative value. + + if (!BBLV.isUndefined() && !BBLV.isOverdefined()) { DEBUG(dbgs() << " reuse BB '" << BB->getName() << "' val=" << BBLV <<'\n'); // Since we're reusing a cached value here, we don't need to update the @@ -516,7 +532,7 @@ 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)); } @@ -557,13 +573,11 @@ 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; @@ -573,11 +587,11 @@ 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; @@ -591,13 +605,19 @@ 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; + } } } } @@ -809,7 +829,7 @@ static bool getEdgeValueLocal(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))); @@ -1009,7 +1029,8 @@ bool LazyValueInfo::runOnFunction(Function &F) { if (PImpl) getCache(PImpl).clear(); - TD = getAnalysisIfAvailable(); + DataLayoutPass *DLP = getAnalysisIfAvailable(); + DL = DLP ? &DLP->getDataLayout() : nullptr; TLI = &getAnalysis(); // Fully lazy. @@ -1025,7 +1046,7 @@ void LazyValueInfo::releaseMemory() { // If the cache was allocated, free it. if (PImpl) { delete &getCache(PImpl); - PImpl = 0; + PImpl = nullptr; } } @@ -1039,7 +1060,7 @@ 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 @@ -1055,7 +1076,7 @@ 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 @@ -1067,9 +1088,9 @@ 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; @@ -1109,16 +1130,16 @@ LazyValueInfo::getPredicateOnEdge(unsigned Pred, Value *V, Constant *C, // If this is an equality comparison, we can try to fold it knowing that // "V != C1". if (Pred == ICmpInst::ICMP_EQ) { - // !C1 == C -> false if C1 == C. + // !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 if C1 == C. + // !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;