X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FVMCore%2FValue.cpp;h=8d0720dc1223d02cf068814adee6961c93bb2eea;hb=ece6c6bb6329748b92403c06ac87f45c43485911;hp=fe1219f9a88fb6abf371b168a9896efbc0263b90;hpb=a43a3f2379360a766725a4138ee9aff4df41b486;p=oota-llvm.git diff --git a/lib/VMCore/Value.cpp b/lib/VMCore/Value.cpp index fe1219f9a88..8d0720dc122 100644 --- a/lib/VMCore/Value.cpp +++ b/lib/VMCore/Value.cpp @@ -22,6 +22,7 @@ #include "llvm/ValueSymbolTable.h" #include "llvm/ADT/SmallString.h" #include "llvm/Support/Debug.h" +#include "llvm/Support/GetElementPtrTypeIterator.h" #include "llvm/Support/ErrorHandling.h" #include "llvm/Support/LeakDetector.h" #include "llvm/Support/ManagedStatic.h" @@ -34,24 +35,21 @@ using namespace llvm; // Value Class //===----------------------------------------------------------------------===// -static inline const Type *checkType(const Type *Ty) { +static inline Type *checkType(Type *Ty) { assert(Ty && "Value defined with a null type: Error!"); - return Ty; + return const_cast(Ty); } -Value::Value(const Type *ty, unsigned scid) +Value::Value(Type *ty, unsigned scid) : SubclassID(scid), HasValueHandle(0), - SubclassOptionalData(0), SubclassData(0), VTy(checkType(ty)), + SubclassOptionalData(0), SubclassData(0), VTy((Type*)checkType(ty)), UseList(0), Name(0) { + // FIXME: Why isn't this in the subclass gunk?? if (isa(this) || isa(this)) - assert((VTy->isFirstClassType() || - VTy == Type::getVoidTy(ty->getContext()) || - isa(ty) || VTy->getTypeID() == Type::StructTyID) && - "invalid CallInst type!"); + assert((VTy->isFirstClassType() || VTy->isVoidTy() || VTy->isStructTy()) && + "invalid CallInst type!"); else if (!isa(this) && !isa(this)) - assert((VTy->isFirstClassType() || - VTy == Type::getVoidTy(ty->getContext()) || - isa(ty)) && + assert((VTy->isFirstClassType() || VTy->isVoidTy()) && "Cannot create non-first-class values except for constants!"); } @@ -68,9 +66,9 @@ Value::~Value() { // a // if (!use_empty()) { - errs() << "While deleting: " << *VTy << " %" << getNameStr() << "\n"; + dbgs() << "While deleting: " << *VTy << " %" << getName() << "\n"; for (use_iterator I = use_begin(), E = use_end(); I != E; ++I) - errs() << "Use still stuck around after Def is destroyed:" + dbgs() << "Use still stuck around after Def is destroyed:" << **I << "\n"; } #endif @@ -78,7 +76,7 @@ Value::~Value() { // If this value is named, destroy the name. This should not be in a symtab // at this point. - if (Name) + if (Name && SubclassID != MDStringVal) Name->Destroy(); // There should be no uses of this object anymore, remove it. @@ -88,7 +86,7 @@ Value::~Value() { /// hasNUses - Return true if this Value has exactly N users. /// bool Value::hasNUses(unsigned N) const { - use_const_iterator UI = use_begin(), E = use_end(); + const_use_iterator UI = use_begin(), E = use_end(); for (; N; --N, ++UI) if (UI == E) return false; // Too few. @@ -99,7 +97,7 @@ bool Value::hasNUses(unsigned N) const { /// logically equivalent to getNumUses() >= N. /// bool Value::hasNUsesOrMore(unsigned N) const { - use_const_iterator UI = use_begin(), E = use_end(); + const_use_iterator UI = use_begin(), E = use_end(); for (; N; --N, ++UI) if (UI == E) return false; // Too few. @@ -110,7 +108,20 @@ bool Value::hasNUsesOrMore(unsigned N) const { /// isUsedInBasicBlock - Return true if this value is used in the specified /// basic block. bool Value::isUsedInBasicBlock(const BasicBlock *BB) const { - for (use_const_iterator I = use_begin(), E = use_end(); I != E; ++I) { + // Start by scanning over the instructions looking for a use before we start + // the expensive use iteration. + unsigned MaxBlockSize = 3; + for (BasicBlock::const_iterator I = BB->begin(), E = BB->end(); I != E; ++I) { + if (std::find(I->op_begin(), I->op_end(), this) != I->op_end()) + return true; + if (MaxBlockSize-- == 0) // If the block is larger fall back to use_iterator + break; + } + + if (MaxBlockSize != 0) // We scanned the entire block and found no use. + return false; + + for (const_use_iterator I = use_begin(), E = use_end(); I != E; ++I) { const Instruction *User = dyn_cast(*I); if (User && User->getParent() == BB) return true; @@ -141,10 +152,6 @@ static bool getSymTab(Value *V, ValueSymbolTable *&ST) { } else if (Argument *A = dyn_cast(V)) { if (Function *P = A->getParent()) ST = &P->getValueSymbolTable(); - } else if (NamedMDNode *N = dyn_cast(V)) { - if (Module *P = N->getParent()) { - ST = &P->getValueSymbolTable(); - } } else if (isa(V)) return true; else { @@ -162,27 +169,22 @@ StringRef Value::getName() const { return Name->getKey(); } -std::string Value::getNameStr() const { - return getName().str(); -} - void Value::setName(const Twine &NewName) { + assert(SubclassID != MDStringVal && + "Cannot set the name of MDString with this method!"); + // Fast path for common IRBuilder case of setName("") when there is no name. if (NewName.isTriviallyEmpty() && !hasName()) return; SmallString<256> NameData; - NewName.toVector(NameData); - - const char *NameStr = NameData.data(); - unsigned NameLen = NameData.size(); + StringRef NameRef = NewName.toStringRef(NameData); // Name isn't changing? - if (getName() == StringRef(NameStr, NameLen)) + if (getName() == NameRef) return; - assert(getType() != Type::getVoidTy(getContext()) && - "Cannot assign a name to void values!"); + assert(!getType()->isVoidTy() && "Cannot assign a name to void values!"); // Get the symbol table to update for this object. ValueSymbolTable *ST; @@ -190,7 +192,7 @@ void Value::setName(const Twine &NewName) { return; // Cannot set a name on this value (e.g. constant). if (!ST) { // No symbol table to update? Just do the change. - if (NameLen == 0) { + if (NameRef.empty()) { // Free the name for this value. Name->Destroy(); Name = 0; @@ -204,7 +206,7 @@ void Value::setName(const Twine &NewName) { // then reallocated. // Create the new name. - Name = ValueName::Create(NameStr, NameStr+NameLen); + Name = ValueName::Create(NameRef.begin(), NameRef.end()); Name->setValue(this); return; } @@ -217,18 +219,20 @@ void Value::setName(const Twine &NewName) { Name->Destroy(); Name = 0; - if (NameLen == 0) + if (NameRef.empty()) return; } // Name is changing to something new. - Name = ST->createValueName(StringRef(NameStr, NameLen), this); + Name = ST->createValueName(NameRef, this); } /// takeName - transfer the name from V to this value, setting V's name to /// empty. It is an error to call V->takeName(V). void Value::takeName(Value *V) { + assert(SubclassID != MDStringVal && "Cannot take the name of an MDString!"); + ValueSymbolTable *ST = 0; // If this value has a name, drop it. if (hasName()) { @@ -264,7 +268,7 @@ void Value::takeName(Value *V) { // Get V's ST, this should always succed, because V has a name. ValueSymbolTable *VST; bool Failure = getSymTab(V, VST); - assert(!Failure && "V has a name, so it should have a ST!"); Failure=Failure; + assert(!Failure && "V has a name, so it should have a ST!"); (void)Failure; // If these values are both in the same symtab, we can do this very fast. // This works even if both values have no symtab yet. @@ -290,17 +294,16 @@ void Value::takeName(Value *V) { } -// uncheckedReplaceAllUsesWith - This is exactly the same as replaceAllUsesWith, -// except that it doesn't have all of the asserts. The asserts fail because we -// are half-way done resolving types, which causes some types to exist as two -// different Type*'s at the same time. This is a sledgehammer to work around -// this problem. -// -void Value::uncheckedReplaceAllUsesWith(Value *New) { +void Value::replaceAllUsesWith(Value *New) { + assert(New && "Value::replaceAllUsesWith() is invalid!"); + assert(New != this && "this->replaceAllUsesWith(this) is NOT valid!"); + assert(New->getType() == getType() && + "replaceAllUses of value with new value of different type!"); + // Notify all ValueHandles (if present) that this value is going away. if (HasValueHandle) ValueHandleBase::ValueIsRAUWd(this, New); - + while (!use_empty()) { Use &U = *UseList; // Must handle Constants specially, we cannot call replaceUsesOfWith on a @@ -311,28 +314,48 @@ void Value::uncheckedReplaceAllUsesWith(Value *New) { continue; } } - + U.set(New); } + + if (BasicBlock *BB = dyn_cast(this)) + BB->replaceSuccessorsPhiUsesWith(cast(New)); } -void Value::replaceAllUsesWith(Value *New) { - assert(New && "Value::replaceAllUsesWith() is invalid!"); - assert(New != this && "this->replaceAllUsesWith(this) is NOT valid!"); - assert(New->getType() == getType() && - "replaceAllUses of value with new value of different type!"); +namespace { +// Various metrics for how much to strip off of pointers. +enum PointerStripKind { + PSK_ZeroIndices, + PSK_InBoundsConstantIndices, + PSK_InBounds +}; - uncheckedReplaceAllUsesWith(New); -} +template +static Value *stripPointerCastsAndOffsets(Value *V) { + if (!V->getType()->isPointerTy()) + return V; -Value *Value::stripPointerCasts() { - if (!isa(getType())) - return this; - Value *V = this; + // Even though we don't look through PHI nodes, we could be called on an + // instruction in an unreachable block, which may be on a cycle. + SmallPtrSet Visited; + + Visited.insert(V); do { if (GEPOperator *GEP = dyn_cast(V)) { - if (!GEP->hasAllZeroIndices()) - return V; + switch (StripKind) { + case PSK_ZeroIndices: + if (!GEP->hasAllZeroIndices()) + return V; + break; + case PSK_InBoundsConstantIndices: + if (!GEP->hasAllConstantIndices()) + return V; + // fallthrough + case PSK_InBounds: + if (!GEP->isInBounds()) + return V; + break; + } V = GEP->getPointerOperand(); } else if (Operator::getOpcode(V) == Instruction::BitCast) { V = cast(V)->getOperand(0); @@ -343,30 +366,91 @@ Value *Value::stripPointerCasts() { } else { return V; } - assert(isa(V->getType()) && "Unexpected operand type!"); - } while (1); + assert(V->getType()->isPointerTy() && "Unexpected operand type!"); + } while (Visited.insert(V)); + + return V; } +} // namespace -Value *Value::getUnderlyingObject() { - if (!isa(getType())) - return this; - Value *V = this; - unsigned MaxLookup = 6; - do { - if (GEPOperator *GEP = dyn_cast(V)) { - V = GEP->getPointerOperand(); - } else if (Operator::getOpcode(V) == Instruction::BitCast) { - V = cast(V)->getOperand(0); - } else if (GlobalAlias *GA = dyn_cast(V)) { - if (GA->mayBeOverridden()) - return V; - V = GA->getAliasee(); - } else { - return V; +Value *Value::stripPointerCasts() { + return stripPointerCastsAndOffsets(this); +} + +Value *Value::stripInBoundsConstantOffsets() { + return stripPointerCastsAndOffsets(this); +} + +Value *Value::stripInBoundsOffsets() { + return stripPointerCastsAndOffsets(this); +} + +/// isDereferenceablePointer - Test if this value is always a pointer to +/// allocated and suitably aligned memory for a simple load or store. +static bool isDereferenceablePointer(const Value *V, + SmallPtrSet &Visited) { + // Note that it is not safe to speculate into a malloc'd region because + // malloc may return null. + // It's also not always safe to follow a bitcast, for example: + // bitcast i8* (alloca i8) to i32* + // would result in a 4-byte load from a 1-byte alloca. Some cases could + // be handled using DataLayout to check sizes and alignments though. + + // These are obviously ok. + if (isa(V)) return true; + + // Global variables which can't collapse to null are ok. + if (const GlobalVariable *GV = dyn_cast(V)) + return !GV->hasExternalWeakLinkage(); + + // byval arguments are ok. + if (const Argument *A = dyn_cast(V)) + return A->hasByValAttr(); + + // For GEPs, determine if the indexing lands within the allocated object. + if (const GEPOperator *GEP = dyn_cast(V)) { + // Conservatively require that the base pointer be fully dereferenceable. + if (!Visited.insert(GEP->getOperand(0))) + return false; + if (!isDereferenceablePointer(GEP->getOperand(0), Visited)) + return false; + // Check the indices. + gep_type_iterator GTI = gep_type_begin(GEP); + for (User::const_op_iterator I = GEP->op_begin()+1, + E = GEP->op_end(); I != E; ++I) { + Value *Index = *I; + Type *Ty = *GTI++; + // Struct indices can't be out of bounds. + if (isa(Ty)) + continue; + ConstantInt *CI = dyn_cast(Index); + if (!CI) + return false; + // Zero is always ok. + if (CI->isZero()) + continue; + // Check to see that it's within the bounds of an array. + ArrayType *ATy = dyn_cast(Ty); + if (!ATy) + return false; + if (CI->getValue().getActiveBits() > 64) + return false; + if (CI->getZExtValue() >= ATy->getNumElements()) + return false; } - assert(isa(V->getType()) && "Unexpected operand type!"); - } while (--MaxLookup); - return V; + // Indices check out; this is dereferenceable. + return true; + } + + // If we don't know, assume the worst. + return false; +} + +/// isDereferenceablePointer - Test if this value is always a pointer to +/// allocated and suitably aligned memory for a simple load or store. +bool Value::isDereferenceablePointer() const { + SmallPtrSet Visited; + return ::isDereferenceablePointer(this, Visited); } /// DoPHITranslation - If this value is a PHI node with CurBB as its parent, @@ -398,7 +482,7 @@ void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) { setPrevPtr(List); if (Next) { Next->setPrevPtr(&Next); - assert(VP == Next->VP && "Added to wrong list?"); + assert(VP.getPointer() == Next->VP.getPointer() && "Added to wrong list?"); } } @@ -414,14 +498,14 @@ void ValueHandleBase::AddToExistingUseListAfter(ValueHandleBase *List) { /// AddToUseList - Add this ValueHandle to the use list for VP. void ValueHandleBase::AddToUseList() { - assert(VP && "Null pointer doesn't have a use list!"); + assert(VP.getPointer() && "Null pointer doesn't have a use list!"); - LLVMContextImpl *pImpl = VP->getContext().pImpl; + LLVMContextImpl *pImpl = VP.getPointer()->getContext().pImpl; - if (VP->HasValueHandle) { + if (VP.getPointer()->HasValueHandle) { // If this value already has a ValueHandle, then it must be in the // ValueHandles map already. - ValueHandleBase *&Entry = pImpl->ValueHandles[VP]; + ValueHandleBase *&Entry = pImpl->ValueHandles[VP.getPointer()]; assert(Entry != 0 && "Value doesn't have any handles?"); AddToExistingUseList(&Entry); return; @@ -435,10 +519,10 @@ void ValueHandleBase::AddToUseList() { DenseMap &Handles = pImpl->ValueHandles; const void *OldBucketPtr = Handles.getPointerIntoBucketsArray(); - ValueHandleBase *&Entry = Handles[VP]; + ValueHandleBase *&Entry = Handles[VP.getPointer()]; assert(Entry == 0 && "Value really did already have handles?"); AddToExistingUseList(&Entry); - VP->HasValueHandle = true; + VP.getPointer()->HasValueHandle = true; // If reallocation didn't happen or if this was the first insertion, don't // walk the table. @@ -450,14 +534,16 @@ void ValueHandleBase::AddToUseList() { // Okay, reallocation did happen. Fix the Prev Pointers. for (DenseMap::iterator I = Handles.begin(), E = Handles.end(); I != E; ++I) { - assert(I->second && I->first == I->second->VP && "List invariant broken!"); + assert(I->second && I->first == I->second->VP.getPointer() && + "List invariant broken!"); I->second->setPrevPtr(&I->second); } } /// RemoveFromUseList - Remove this ValueHandle from its current use list. void ValueHandleBase::RemoveFromUseList() { - assert(VP && VP->HasValueHandle && "Pointer doesn't have a use list!"); + assert(VP.getPointer() && VP.getPointer()->HasValueHandle && + "Pointer doesn't have a use list!"); // Unlink this from its use list. ValueHandleBase **PrevPtr = getPrevPtr(); @@ -473,11 +559,11 @@ void ValueHandleBase::RemoveFromUseList() { // If the Next pointer was null, then it is possible that this was the last // ValueHandle watching VP. If so, delete its entry from the ValueHandles // map. - LLVMContextImpl *pImpl = VP->getContext().pImpl; + LLVMContextImpl *pImpl = VP.getPointer()->getContext().pImpl; DenseMap &Handles = pImpl->ValueHandles; if (Handles.isPointerIntoBucketsArray(PrevPtr)) { - Handles.erase(VP); - VP->HasValueHandle = false; + Handles.erase(VP.getPointer()); + VP.getPointer()->HasValueHandle = false; } } @@ -491,10 +577,15 @@ void ValueHandleBase::ValueIsDeleted(Value *V) { ValueHandleBase *Entry = pImpl->ValueHandles[V]; assert(Entry && "Value bit set but no entries exist"); - // We use a local ValueHandleBase as an iterator so that - // ValueHandles can add and remove themselves from the list without - // breaking our iteration. This is not really an AssertingVH; we - // just have to give ValueHandleBase some kind. + // We use a local ValueHandleBase as an iterator so that ValueHandles can add + // and remove themselves from the list without breaking our iteration. This + // is not really an AssertingVH; we just have to give ValueHandleBase a kind. + // Note that we deliberately do not the support the case when dropping a value + // handle results in a new value handle being permanently added to the list + // (as might occur in theory for CallbackVH's): the new value handle will not + // be processed and the checking code will mete out righteous punishment if + // the handle is still present once we have finished processing all the other + // value handles (it is fine to momentarily add then remove a value handle). for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) { Iterator.RemoveFromUseList(); Iterator.AddToExistingUseListAfter(Entry); @@ -522,7 +613,7 @@ void ValueHandleBase::ValueIsDeleted(Value *V) { // All callbacks, weak references, and assertingVHs should be dropped by now. if (V->HasValueHandle) { #ifndef NDEBUG // Only in +Asserts mode... - errs() << "While deleting: " << *V->getType() << " %" << V->getNameStr() + dbgs() << "While deleting: " << *V->getType() << " %" << V->getName() << "\n"; if (pImpl->ValueHandles[V]->getKind() == Assert) llvm_unreachable("An asserting value handle still pointed to this" @@ -575,31 +666,29 @@ void ValueHandleBase::ValueIsRAUWd(Value *Old, Value *New) { break; } } -} -/// ~CallbackVH. Empty, but defined here to avoid emitting the vtable -/// more than once. -CallbackVH::~CallbackVH() {} +#ifndef NDEBUG + // If any new tracking or weak value handles were added while processing the + // list, then complain about it now. + if (Old->HasValueHandle) + for (Entry = pImpl->ValueHandles[Old]; Entry; Entry = Entry->Next) + switch (Entry->getKind()) { + case Tracking: + case Weak: + dbgs() << "After RAUW from " << *Old->getType() << " %" + << Old->getName() << " to " << *New->getType() << " %" + << New->getName() << "\n"; + llvm_unreachable("A tracking or weak value handle still pointed to the" + " old value!\n"); + default: + break; + } +#endif +} +// Default implementation for CallbackVH. +void CallbackVH::allUsesReplacedWith(Value *) {} -//===----------------------------------------------------------------------===// -// User Class -//===----------------------------------------------------------------------===// - -// replaceUsesOfWith - Replaces all references to the "From" definition with -// references to the "To" definition. -// -void User::replaceUsesOfWith(Value *From, Value *To) { - if (From == To) return; // Duh what? - - assert((!isa(this) || isa(this)) && - "Cannot call User::replaceUsesOfWith on a constant!"); - - for (unsigned i = 0, E = getNumOperands(); i != E; ++i) - if (getOperand(i) == From) { // Is This operand is pointing to oldval? - // The side effects of this setOperand call include linking to - // "To", adding "this" to the uses list of To, and - // most importantly, removing "this" from the use list of "From". - setOperand(i, To); // Fix it now... - } +void CallbackVH::deleted() { + setValPtr(NULL); }