llvm/lib/VMCore/Value.cpp

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//===-- 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/Constant.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/InstrTypes.h"
#include "llvm/Instructions.h"
#include "llvm/Module.h"
#include "llvm/ValueSymbolTable.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/LeakDetector.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/ValueHandle.h"
#include "llvm/System/RWMutex.h"
#include "llvm/System/Threading.h"
#include "llvm/ADT/DenseMap.h"
#include <algorithm>
using namespace llvm;
//===----------------------------------------------------------------------===//
// Value Class
//===----------------------------------------------------------------------===//
static inline const Type *checkType(const Type *Ty) {
assert(Ty && "Value defined with a null type: Error!");
return Ty;
}
Value::Value(const Type *ty, unsigned scid)
: SubclassID(scid), HasValueHandle(0), SubclassData(0), VTy(checkType(ty)),
UseList(0), Name(0) {
if (isa<CallInst>(this) || isa<InvokeInst>(this))
assert((VTy->isFirstClassType() || VTy == Type::VoidTy ||
isa<OpaqueType>(ty) || VTy->getTypeID() == Type::StructTyID) &&
"invalid CallInst type!");
else if (!isa<Constant>(this) && !isa<BasicBlock>(this))
assert((VTy->isFirstClassType() || VTy == Type::VoidTy ||
isa<OpaqueType>(ty)) &&
"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()) {
cerr << "While deleting: " << *VTy << " %" << getNameStr() << "\n";
for (use_iterator I = use_begin(), E = use_end(); I != E; ++I)
cerr << "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)
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 {
use_const_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 {
use_const_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 {
for (use_const_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 {
assert(isa<Constant>(V) && "Unknown value type!");
return true; // no name is setable for this.
}
return false;
}
/// getNameStart - Return a pointer to a null terminated string for this name.
/// Note that names can have null characters within the string as well as at
/// their end. This always returns a non-null pointer.
const char *Value::getNameStart() const {
if (Name == 0) return "";
return Name->getKeyData();
}
/// getNameLen - Return the length of the string, correctly handling nul
/// characters embedded into them.
unsigned Value::getNameLen() const {
return Name ? Name->getKeyLength() : 0;
}
/// isName - Return true if this value has the name specified by the provided
/// nul terminated string.
bool Value::isName(const char *N) const {
unsigned InLen = strlen(N);
return InLen == getNameLen() && memcmp(getNameStart(), N, InLen) == 0;
}
std::string Value::getNameStr() const {
if (Name == 0) return "";
return std::string(Name->getKeyData(),
Name->getKeyData()+Name->getKeyLength());
}
void Value::setName(const std::string &name) {
setName(&name[0], name.size());
}
void Value::setName(const char *Name) {
setName(Name, Name ? strlen(Name) : 0);
}
void Value::setName(const char *NameStr, unsigned NameLen) {
if (NameLen == 0 && !hasName()) return;
assert(getType() != Type::VoidTy && "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 (NameLen == 0) {
// Free the name for this value.
Name->Destroy();
Name = 0;
return;
}
if (Name) {
// Name isn't changing?
if (NameLen == Name->getKeyLength() &&
!memcmp(Name->getKeyData(), NameStr, NameLen))
return;
Name->Destroy();
}
// NOTE: Could optimize for the case the name is shrinking to not deallocate
// then reallocated.
// Create the new name.
Name = ValueName::Create(NameStr, NameStr+NameLen);
Name->setValue(this);
return;
}
// NOTE: Could optimize for the case the name is shrinking to not deallocate
// then reallocated.
if (hasName()) {
// Name isn't changing?
if (NameLen == Name->getKeyLength() &&
!memcmp(Name->getKeyData(), NameStr, NameLen))
return;
// Remove old name.
ST->removeValueName(Name);
Name->Destroy();
Name = 0;
if (NameLen == 0)
return;
}
// Name is changing to something new.
Name = ST->createValueName(NameStr, NameLen, 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) {
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(0, 0);
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(0, 0);
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!"); Failure=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);
}
// 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) {
// 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);
}
}
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!");
uncheckedReplaceAllUsesWith(New);
}
Value *Value::stripPointerCasts() {
if (!isa<PointerType>(getType()))
return this;
Value *V = this;
do {
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (CE->getOpcode() == Instruction::GetElementPtr) {
for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
if (!CE->getOperand(i)->isNullValue())
return V;
V = CE->getOperand(0);
} else if (CE->getOpcode() == Instruction::BitCast) {
V = CE->getOperand(0);
} else {
return V;
}
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) {
if (!GEP->hasAllZeroIndices())
return V;
V = GEP->getOperand(0);
} else if (BitCastInst *CI = dyn_cast<BitCastInst>(V)) {
V = CI->getOperand(0);
} else {
return V;
}
assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
} while (1);
}
Value *Value::getUnderlyingObject() {
if (!isa<PointerType>(getType()))
return this;
Value *V = this;
unsigned MaxLookup = 6;
do {
if (Instruction *I = dyn_cast<Instruction>(V)) {
if (!isa<BitCastInst>(I) && !isa<GetElementPtrInst>(I))
return V;
V = I->getOperand(0);
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
if (CE->getOpcode() != Instruction::BitCast &&
CE->getOpcode() != Instruction::GetElementPtr)
return V;
V = CE->getOperand(0);
} else {
return V;
}
assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
} while (--MaxLookup);
return V;
}
/// 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;
}
//===----------------------------------------------------------------------===//
// ValueHandleBase Class
//===----------------------------------------------------------------------===//
/// ValueHandles - This map keeps track of all of the value handles that are
/// watching a Value*. The Value::HasValueHandle bit is used to know whether or
/// not a value has an entry in this map.
typedef DenseMap<Value*, ValueHandleBase*> ValueHandlesTy;
static ManagedStatic<ValueHandlesTy> ValueHandles;
static ManagedStatic<sys::SmartRWMutex<true> > ValueHandlesLock;
/// 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 == Next->VP && "Added to wrong list?");
}
}
/// AddToUseList - Add this ValueHandle to the use list for VP.
void ValueHandleBase::AddToUseList() {
assert(VP && "Null pointer doesn't have a use list!");
if (VP->HasValueHandle) {
// If this value already has a ValueHandle, then it must be in the
// ValueHandles map already.
sys::SmartScopedReader<true> Reader(&*ValueHandlesLock);
ValueHandleBase *&Entry = (*ValueHandles)[VP];
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.
sys::SmartScopedWriter<true> Writer(&*ValueHandlesLock);
ValueHandlesTy &Handles = *ValueHandles;
const void *OldBucketPtr = Handles.getPointerIntoBucketsArray();
ValueHandleBase *&Entry = Handles[VP];
assert(Entry == 0 && "Value really did already have handles?");
AddToExistingUseList(&Entry);
VP->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 (ValueHandlesTy::iterator I = Handles.begin(), E = Handles.end();
I != E; ++I) {
assert(I->second && I->first == I->second->VP && "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!");
// 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.
sys::SmartScopedWriter<true> Writer(&*ValueHandlesLock);
ValueHandlesTy &Handles = *ValueHandles;
if (Handles.isPointerIntoBucketsArray(PrevPtr)) {
Handles.erase(VP);
VP->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.
ValueHandlesLock->reader_acquire();
ValueHandleBase *Entry = (*ValueHandles)[V];
ValueHandlesLock->reader_release();
assert(Entry && "Value bit set but no entries exist");
while (Entry) {
// Advance pointer to avoid invalidation.
ValueHandleBase *ThisNode = Entry;
Entry = Entry->Next;
switch (ThisNode->getKind()) {
case Assert:
#ifndef NDEBUG // Only in -g mode...
cerr << "While deleting: " << *V->getType() << " %" << V->getNameStr()
<< "\n";
#endif
cerr << "An asserting value handle still pointed to this value!\n";
abort();
case Weak:
// Weak just goes to null, which will unlink it from the list.
ThisNode->operator=(0);
break;
case Callback:
// Forward to the subclass's implementation.
static_cast<CallbackVH*>(ThisNode)->deleted();
break;
}
}
// All callbacks and weak references should be dropped by now.
assert(!V->HasValueHandle && "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.
ValueHandlesLock->reader_acquire();
ValueHandleBase *Entry = (*ValueHandles)[Old];
ValueHandlesLock->reader_release();
assert(Entry && "Value bit set but no entries exist");
while (Entry) {
// Advance pointer to avoid invalidation.
ValueHandleBase *ThisNode = Entry;
Entry = Entry->Next;
switch (ThisNode->getKind()) {
case Assert:
// Asserting handle does not follow RAUW implicitly.
break;
case Weak:
// Weak goes to the new value, which will unlink it from Old's list.
ThisNode->operator=(New);
break;
case Callback:
// Forward to the subclass's implementation.
static_cast<CallbackVH*>(ThisNode)->allUsesReplacedWith(New);
break;
}
}
}
/// ~CallbackVH. Empty, but defined here to avoid emitting the vtable
/// more than once.
CallbackVH::~CallbackVH() {}
//===----------------------------------------------------------------------===//
// 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<Constant>(this) || isa<GlobalValue>(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...
}
}