+++ /dev/null
-//===-- Value.cpp - Implement the Value class -----------------------------===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file implements the Value, ValueHandle, and User classes.
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Value.h"
-#include "LLVMContextImpl.h"
-#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/SmallString.h"
-#include "llvm/Constant.h"
-#include "llvm/Constants.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/InstrTypes.h"
-#include "llvm/Instructions.h"
-#include "llvm/Module.h"
-#include "llvm/Operator.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/Support/ErrorHandling.h"
-#include "llvm/Support/GetElementPtrTypeIterator.h"
-#include "llvm/Support/LeakDetector.h"
-#include "llvm/Support/ManagedStatic.h"
-#include "llvm/Support/ValueHandle.h"
-#include "llvm/ValueSymbolTable.h"
-#include <algorithm>
-using namespace llvm;
-
-//===----------------------------------------------------------------------===//
-// Value Class
-//===----------------------------------------------------------------------===//
-
-static inline Type *checkType(Type *Ty) {
- assert(Ty && "Value defined with a null type: Error!");
- return const_cast<Type*>(Ty);
-}
-
-Value::Value(Type *ty, unsigned scid)
- : SubclassID(scid), HasValueHandle(0),
- SubclassOptionalData(0), SubclassData(0), VTy((Type*)checkType(ty)),
- UseList(0), Name(0) {
- // FIXME: Why isn't this in the subclass gunk??
- // Note, we cannot call isa<CallInst> before the CallInst has been
- // constructed.
- if (SubclassID == Instruction::Call || SubclassID == Instruction::Invoke)
- assert((VTy->isFirstClassType() || VTy->isVoidTy() || VTy->isStructTy()) &&
- "invalid CallInst type!");
- else if (SubclassID != BasicBlockVal &&
- (SubclassID < ConstantFirstVal || SubclassID > ConstantLastVal))
- assert((VTy->isFirstClassType() || VTy->isVoidTy()) &&
- "Cannot create non-first-class values except for constants!");
-}
-
-Value::~Value() {
- // Notify all ValueHandles (if present) that this value is going away.
- if (HasValueHandle)
- ValueHandleBase::ValueIsDeleted(this);
-
-#ifndef NDEBUG // Only in -g mode...
- // Check to make sure that there are no uses of this value that are still
- // around when the value is destroyed. If there are, then we have a dangling
- // reference and something is wrong. This code is here to print out what is
- // still being referenced. The value in question should be printed as
- // a <badref>
- //
- if (!use_empty()) {
- dbgs() << "While deleting: " << *VTy << " %" << getName() << "\n";
- for (use_iterator I = use_begin(), E = use_end(); I != E; ++I)
- dbgs() << "Use still stuck around after Def is destroyed:"
- << **I << "\n";
- }
-#endif
- assert(use_empty() && "Uses remain when a value is destroyed!");
-
- // If this value is named, destroy the name. This should not be in a symtab
- // at this point.
- if (Name && SubclassID != MDStringVal)
- Name->Destroy();
-
- // There should be no uses of this object anymore, remove it.
- LeakDetector::removeGarbageObject(this);
-}
-
-/// hasNUses - Return true if this Value has exactly N users.
-///
-bool Value::hasNUses(unsigned N) const {
- const_use_iterator UI = use_begin(), E = use_end();
-
- for (; N; --N, ++UI)
- if (UI == E) return false; // Too few.
- return UI == E;
-}
-
-/// hasNUsesOrMore - Return true if this value has N users or more. This is
-/// logically equivalent to getNumUses() >= N.
-///
-bool Value::hasNUsesOrMore(unsigned N) const {
- const_use_iterator UI = use_begin(), E = use_end();
-
- for (; N; --N, ++UI)
- if (UI == E) return false; // Too few.
-
- return true;
-}
-
-/// isUsedInBasicBlock - Return true if this value is used in the specified
-/// basic block.
-bool Value::isUsedInBasicBlock(const BasicBlock *BB) const {
- // 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<Instruction>(*I);
- if (User && User->getParent() == BB)
- return true;
- }
- return false;
-}
-
-
-/// getNumUses - This method computes the number of uses of this Value. This
-/// is a linear time operation. Use hasOneUse or hasNUses to check for specific
-/// values.
-unsigned Value::getNumUses() const {
- return (unsigned)std::distance(use_begin(), use_end());
-}
-
-static bool getSymTab(Value *V, ValueSymbolTable *&ST) {
- ST = 0;
- if (Instruction *I = dyn_cast<Instruction>(V)) {
- if (BasicBlock *P = I->getParent())
- if (Function *PP = P->getParent())
- ST = &PP->getValueSymbolTable();
- } else if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
- if (Function *P = BB->getParent())
- ST = &P->getValueSymbolTable();
- } else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
- if (Module *P = GV->getParent())
- ST = &P->getValueSymbolTable();
- } else if (Argument *A = dyn_cast<Argument>(V)) {
- if (Function *P = A->getParent())
- ST = &P->getValueSymbolTable();
- } else if (isa<MDString>(V))
- return true;
- else {
- assert(isa<Constant>(V) && "Unknown value type!");
- return true; // no name is setable for this.
- }
- return false;
-}
-
-StringRef Value::getName() const {
- // Make sure the empty string is still a C string. For historical reasons,
- // some clients want to call .data() on the result and expect it to be null
- // terminated.
- if (!Name) return StringRef("", 0);
- return Name->getKey();
-}
-
-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;
- StringRef NameRef = NewName.toStringRef(NameData);
-
- // Name isn't changing?
- if (getName() == NameRef)
- return;
-
- assert(!getType()->isVoidTy() && "Cannot assign a name to void values!");
-
- // Get the symbol table to update for this object.
- ValueSymbolTable *ST;
- if (getSymTab(this, ST))
- return; // Cannot set a name on this value (e.g. constant).
-
- if (!ST) { // No symbol table to update? Just do the change.
- if (NameRef.empty()) {
- // Free the name for this value.
- Name->Destroy();
- Name = 0;
- return;
- }
-
- if (Name)
- Name->Destroy();
-
- // NOTE: Could optimize for the case the name is shrinking to not deallocate
- // then reallocated.
-
- // Create the new name.
- Name = ValueName::Create(NameRef.begin(), NameRef.end());
- Name->setValue(this);
- return;
- }
-
- // NOTE: Could optimize for the case the name is shrinking to not deallocate
- // then reallocated.
- if (hasName()) {
- // Remove old name.
- ST->removeValueName(Name);
- Name->Destroy();
- Name = 0;
-
- if (NameRef.empty())
- return;
- }
-
- // Name is changing to something new.
- 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()) {
- // Get the symtab this is in.
- if (getSymTab(this, ST)) {
- // We can't set a name on this value, but we need to clear V's name if
- // it has one.
- if (V->hasName()) V->setName("");
- return; // Cannot set a name on this value (e.g. constant).
- }
-
- // Remove old name.
- if (ST)
- ST->removeValueName(Name);
- Name->Destroy();
- Name = 0;
- }
-
- // Now we know that this has no name.
-
- // If V has no name either, we're done.
- if (!V->hasName()) return;
-
- // Get this's symtab if we didn't before.
- if (!ST) {
- if (getSymTab(this, ST)) {
- // Clear V's name.
- V->setName("");
- return; // Cannot set a name on this value (e.g. constant).
- }
- }
-
- // 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!"); (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.
- if (ST == VST) {
- // Take the name!
- Name = V->Name;
- V->Name = 0;
- Name->setValue(this);
- return;
- }
-
- // Otherwise, things are slightly more complex. Remove V's name from VST and
- // then reinsert it into ST.
-
- if (VST)
- VST->removeValueName(V->Name);
- Name = V->Name;
- V->Name = 0;
- Name->setValue(this);
-
- if (ST)
- ST->reinsertValue(this);
-}
-
-
-void Value::replaceAllUsesWith(Value *New) {
- assert(New && "Value::replaceAllUsesWith(<null>) 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
- // constant because they are uniqued.
- if (Constant *C = dyn_cast<Constant>(U.getUser())) {
- if (!isa<GlobalValue>(C)) {
- C->replaceUsesOfWithOnConstant(this, New, &U);
- continue;
- }
- }
-
- U.set(New);
- }
-
- if (BasicBlock *BB = dyn_cast<BasicBlock>(this))
- BB->replaceSuccessorsPhiUsesWith(cast<BasicBlock>(New));
-}
-
-namespace {
-// Various metrics for how much to strip off of pointers.
-enum PointerStripKind {
- PSK_ZeroIndices,
- PSK_InBoundsConstantIndices,
- PSK_InBounds
-};
-
-template <PointerStripKind StripKind>
-static Value *stripPointerCastsAndOffsets(Value *V) {
- if (!V->getType()->isPointerTy())
- return V;
-
- // 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<Value *, 4> Visited;
-
- Visited.insert(V);
- do {
- if (GEPOperator *GEP = dyn_cast<GEPOperator>(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<Operator>(V)->getOperand(0);
- } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
- if (GA->mayBeOverridden())
- return V;
- V = GA->getAliasee();
- } else {
- return V;
- }
- assert(V->getType()->isPointerTy() && "Unexpected operand type!");
- } while (Visited.insert(V));
-
- return V;
-}
-} // namespace
-
-Value *Value::stripPointerCasts() {
- return stripPointerCastsAndOffsets<PSK_ZeroIndices>(this);
-}
-
-Value *Value::stripInBoundsConstantOffsets() {
- return stripPointerCastsAndOffsets<PSK_InBoundsConstantIndices>(this);
-}
-
-Value *Value::stripInBoundsOffsets() {
- return stripPointerCastsAndOffsets<PSK_InBounds>(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<const Value *, 32> &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<AllocaInst>(V)) return true;
-
- // Global variables which can't collapse to null are ok.
- if (const GlobalVariable *GV = dyn_cast<GlobalVariable>(V))
- return !GV->hasExternalWeakLinkage();
-
- // byval arguments are ok.
- if (const Argument *A = dyn_cast<Argument>(V))
- return A->hasByValAttr();
-
- // For GEPs, determine if the indexing lands within the allocated object.
- if (const GEPOperator *GEP = dyn_cast<GEPOperator>(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<StructType>(Ty))
- continue;
- ConstantInt *CI = dyn_cast<ConstantInt>(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<ArrayType>(Ty);
- if (!ATy)
- return false;
- if (CI->getValue().getActiveBits() > 64)
- return false;
- if (CI->getZExtValue() >= ATy->getNumElements())
- return false;
- }
- // 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<const Value *, 32> Visited;
- return ::isDereferenceablePointer(this, Visited);
-}
-
-/// DoPHITranslation - If this value is a PHI node with CurBB as its parent,
-/// return the value in the PHI node corresponding to PredBB. If not, return
-/// ourself. This is useful if you want to know the value something has in a
-/// predecessor block.
-Value *Value::DoPHITranslation(const BasicBlock *CurBB,
- const BasicBlock *PredBB) {
- PHINode *PN = dyn_cast<PHINode>(this);
- if (PN && PN->getParent() == CurBB)
- return PN->getIncomingValueForBlock(PredBB);
- return this;
-}
-
-LLVMContext &Value::getContext() const { return VTy->getContext(); }
-
-//===----------------------------------------------------------------------===//
-// ValueHandleBase Class
-//===----------------------------------------------------------------------===//
-
-/// AddToExistingUseList - Add this ValueHandle to the use list for VP, where
-/// List is known to point into the existing use list.
-void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) {
- assert(List && "Handle list is null?");
-
- // Splice ourselves into the list.
- Next = *List;
- *List = this;
- setPrevPtr(List);
- if (Next) {
- Next->setPrevPtr(&Next);
- assert(VP.getPointer() == Next->VP.getPointer() && "Added to wrong list?");
- }
-}
-
-void ValueHandleBase::AddToExistingUseListAfter(ValueHandleBase *List) {
- assert(List && "Must insert after existing node");
-
- Next = List->Next;
- setPrevPtr(&List->Next);
- List->Next = this;
- if (Next)
- Next->setPrevPtr(&Next);
-}
-
-/// AddToUseList - Add this ValueHandle to the use list for VP.
-void ValueHandleBase::AddToUseList() {
- assert(VP.getPointer() && "Null pointer doesn't have a use list!");
-
- LLVMContextImpl *pImpl = VP.getPointer()->getContext().pImpl;
-
- 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.getPointer()];
- assert(Entry != 0 && "Value doesn't have any handles?");
- AddToExistingUseList(&Entry);
- return;
- }
-
- // Ok, it doesn't have any handles yet, so we must insert it into the
- // DenseMap. However, doing this insertion could cause the DenseMap to
- // reallocate itself, which would invalidate all of the PrevP pointers that
- // point into the old table. Handle this by checking for reallocation and
- // updating the stale pointers only if needed.
- DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
- const void *OldBucketPtr = Handles.getPointerIntoBucketsArray();
-
- ValueHandleBase *&Entry = Handles[VP.getPointer()];
- assert(Entry == 0 && "Value really did already have handles?");
- AddToExistingUseList(&Entry);
- VP.getPointer()->HasValueHandle = true;
-
- // If reallocation didn't happen or if this was the first insertion, don't
- // walk the table.
- if (Handles.isPointerIntoBucketsArray(OldBucketPtr) ||
- Handles.size() == 1) {
- return;
- }
-
- // Okay, reallocation did happen. Fix the Prev Pointers.
- for (DenseMap<Value*, ValueHandleBase*>::iterator I = Handles.begin(),
- E = Handles.end(); I != E; ++I) {
- 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.getPointer() && VP.getPointer()->HasValueHandle &&
- "Pointer doesn't have a use list!");
-
- // Unlink this from its use list.
- ValueHandleBase **PrevPtr = getPrevPtr();
- assert(*PrevPtr == this && "List invariant broken");
-
- *PrevPtr = Next;
- if (Next) {
- assert(Next->getPrevPtr() == &Next && "List invariant broken");
- Next->setPrevPtr(PrevPtr);
- return;
- }
-
- // 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.getPointer()->getContext().pImpl;
- DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
- if (Handles.isPointerIntoBucketsArray(PrevPtr)) {
- Handles.erase(VP.getPointer());
- VP.getPointer()->HasValueHandle = false;
- }
-}
-
-
-void ValueHandleBase::ValueIsDeleted(Value *V) {
- assert(V->HasValueHandle && "Should only be called if ValueHandles present");
-
- // Get the linked list base, which is guaranteed to exist since the
- // HasValueHandle flag is set.
- LLVMContextImpl *pImpl = V->getContext().pImpl;
- 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 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);
- assert(Entry->Next == &Iterator && "Loop invariant broken.");
-
- switch (Entry->getKind()) {
- case Assert:
- break;
- case Tracking:
- // Mark that this value has been deleted by setting it to an invalid Value
- // pointer.
- Entry->operator=(DenseMapInfo<Value *>::getTombstoneKey());
- break;
- case Weak:
- // Weak just goes to null, which will unlink it from the list.
- Entry->operator=(0);
- break;
- case Callback:
- // Forward to the subclass's implementation.
- static_cast<CallbackVH*>(Entry)->deleted();
- break;
- }
- }
-
- // All callbacks, weak references, and assertingVHs should be dropped by now.
- if (V->HasValueHandle) {
-#ifndef NDEBUG // Only in +Asserts mode...
- dbgs() << "While deleting: " << *V->getType() << " %" << V->getName()
- << "\n";
- if (pImpl->ValueHandles[V]->getKind() == Assert)
- llvm_unreachable("An asserting value handle still pointed to this"
- " value!");
-
-#endif
- llvm_unreachable("All references to V were not removed?");
- }
-}
-
-
-void ValueHandleBase::ValueIsRAUWd(Value *Old, Value *New) {
- assert(Old->HasValueHandle &&"Should only be called if ValueHandles present");
- assert(Old != New && "Changing value into itself!");
-
- // Get the linked list base, which is guaranteed to exist since the
- // HasValueHandle flag is set.
- LLVMContextImpl *pImpl = Old->getContext().pImpl;
- ValueHandleBase *Entry = pImpl->ValueHandles[Old];
-
- 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.
- for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) {
- Iterator.RemoveFromUseList();
- Iterator.AddToExistingUseListAfter(Entry);
- assert(Entry->Next == &Iterator && "Loop invariant broken.");
-
- switch (Entry->getKind()) {
- case Assert:
- // Asserting handle does not follow RAUW implicitly.
- break;
- case Tracking:
- // Tracking goes to new value like a WeakVH. Note that this may make it
- // something incompatible with its templated type. We don't want to have a
- // virtual (or inline) interface to handle this though, so instead we make
- // the TrackingVH accessors guarantee that a client never sees this value.
-
- // FALLTHROUGH
- case Weak:
- // Weak goes to the new value, which will unlink it from Old's list.
- Entry->operator=(New);
- break;
- case Callback:
- // Forward to the subclass's implementation.
- static_cast<CallbackVH*>(Entry)->allUsesReplacedWith(New);
- break;
- }
- }
-
-#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 *) {}
-
-void CallbackVH::deleted() {
- setValPtr(NULL);
-}
projects / oota-llvm.git / blobdiff