1 //===-- Value.cpp - Implement the Value class -----------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the Value, ValueHandle, and User classes.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Constant.h"
15 #include "llvm/Constants.h"
16 #include "llvm/DerivedTypes.h"
17 #include "llvm/InstrTypes.h"
18 #include "llvm/Instructions.h"
19 #include "llvm/Operator.h"
20 #include "llvm/Module.h"
21 #include "llvm/MDNode.h"
22 #include "llvm/ValueSymbolTable.h"
23 #include "llvm/Support/Debug.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Support/LeakDetector.h"
26 #include "llvm/Support/ManagedStatic.h"
27 #include "llvm/Support/ValueHandle.h"
28 #include "llvm/Support/raw_ostream.h"
29 #include "llvm/System/RWMutex.h"
30 #include "llvm/System/Threading.h"
31 #include "llvm/ADT/DenseMap.h"
35 //===----------------------------------------------------------------------===//
37 //===----------------------------------------------------------------------===//
39 static inline const Type *checkType(const Type *Ty) {
40 assert(Ty && "Value defined with a null type: Error!");
44 Value::Value(const Type *ty, unsigned scid)
45 : SubclassID(scid), HasValueHandle(0), SubclassOptionalData(0),
46 SubclassData(0), VTy(checkType(ty)),
48 if (isa<CallInst>(this) || isa<InvokeInst>(this))
49 assert((VTy->isFirstClassType() || VTy == Type::VoidTy ||
50 isa<OpaqueType>(ty) || VTy->getTypeID() == Type::StructTyID) &&
51 "invalid CallInst type!");
52 else if (!isa<Constant>(this) && !isa<BasicBlock>(this))
53 assert((VTy->isFirstClassType() || VTy == Type::VoidTy ||
54 isa<OpaqueType>(ty)) &&
55 "Cannot create non-first-class values except for constants!");
59 // Notify all ValueHandles (if present) that this value is going away.
61 ValueHandleBase::ValueIsDeleted(this);
63 #ifndef NDEBUG // Only in -g mode...
64 // Check to make sure that there are no uses of this value that are still
65 // around when the value is destroyed. If there are, then we have a dangling
66 // reference and something is wrong. This code is here to print out what is
67 // still being referenced. The value in question should be printed as
71 cerr << "While deleting: " << *VTy << " %" << getNameStr() << "\n";
72 for (use_iterator I = use_begin(), E = use_end(); I != E; ++I)
73 cerr << "Use still stuck around after Def is destroyed:"
77 assert(use_empty() && "Uses remain when a value is destroyed!");
79 // If this value is named, destroy the name. This should not be in a symtab
84 // There should be no uses of this object anymore, remove it.
85 LeakDetector::removeGarbageObject(this);
88 /// hasNUses - Return true if this Value has exactly N users.
90 bool Value::hasNUses(unsigned N) const {
91 use_const_iterator UI = use_begin(), E = use_end();
94 if (UI == E) return false; // Too few.
98 /// hasNUsesOrMore - Return true if this value has N users or more. This is
99 /// logically equivalent to getNumUses() >= N.
101 bool Value::hasNUsesOrMore(unsigned N) const {
102 use_const_iterator UI = use_begin(), E = use_end();
105 if (UI == E) return false; // Too few.
110 /// isUsedInBasicBlock - Return true if this value is used in the specified
112 bool Value::isUsedInBasicBlock(const BasicBlock *BB) const {
113 for (use_const_iterator I = use_begin(), E = use_end(); I != E; ++I) {
114 const Instruction *User = dyn_cast<Instruction>(*I);
115 if (User && User->getParent() == BB)
122 /// getNumUses - This method computes the number of uses of this Value. This
123 /// is a linear time operation. Use hasOneUse or hasNUses to check for specific
125 unsigned Value::getNumUses() const {
126 return (unsigned)std::distance(use_begin(), use_end());
129 static bool getSymTab(Value *V, ValueSymbolTable *&ST) {
131 if (Instruction *I = dyn_cast<Instruction>(V)) {
132 if (BasicBlock *P = I->getParent())
133 if (Function *PP = P->getParent())
134 ST = &PP->getValueSymbolTable();
135 } else if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
136 if (Function *P = BB->getParent())
137 ST = &P->getValueSymbolTable();
138 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
139 if (Module *P = GV->getParent())
140 ST = &P->getValueSymbolTable();
141 } else if (Argument *A = dyn_cast<Argument>(V)) {
142 if (Function *P = A->getParent())
143 ST = &P->getValueSymbolTable();
144 } else if (isa<MDString>(V))
147 assert(isa<Constant>(V) && "Unknown value type!");
148 return true; // no name is setable for this.
153 /// getNameStart - Return a pointer to a null terminated string for this name.
154 /// Note that names can have null characters within the string as well as at
155 /// their end. This always returns a non-null pointer.
156 const char *Value::getNameStart() const {
157 if (Name == 0) return "";
158 return Name->getKeyData();
161 /// getNameLen - Return the length of the string, correctly handling nul
162 /// characters embedded into them.
163 unsigned Value::getNameLen() const {
164 return Name ? Name->getKeyLength() : 0;
167 /// isName - Return true if this value has the name specified by the provided
168 /// nul terminated string.
169 bool Value::isName(const char *N) const {
170 unsigned InLen = strlen(N);
171 return InLen == getNameLen() && memcmp(getNameStart(), N, InLen) == 0;
175 std::string Value::getNameStr() const {
176 if (Name == 0) return "";
177 return std::string(Name->getKeyData(),
178 Name->getKeyData()+Name->getKeyLength());
181 void Value::setName(const std::string &name) {
182 setName(&name[0], name.size());
185 void Value::setName(const char *Name) {
186 setName(Name, Name ? strlen(Name) : 0);
189 void Value::setName(const char *NameStr, unsigned NameLen) {
190 if (NameLen == 0 && !hasName()) return;
191 assert(getType() != Type::VoidTy && "Cannot assign a name to void values!");
193 // Get the symbol table to update for this object.
194 ValueSymbolTable *ST;
195 if (getSymTab(this, ST))
196 return; // Cannot set a name on this value (e.g. constant).
198 if (!ST) { // No symbol table to update? Just do the change.
200 // Free the name for this value.
207 // Name isn't changing?
208 if (NameLen == Name->getKeyLength() &&
209 !memcmp(Name->getKeyData(), NameStr, NameLen))
214 // NOTE: Could optimize for the case the name is shrinking to not deallocate
217 // Create the new name.
218 Name = ValueName::Create(NameStr, NameStr+NameLen);
219 Name->setValue(this);
223 // NOTE: Could optimize for the case the name is shrinking to not deallocate
226 // Name isn't changing?
227 if (NameLen == Name->getKeyLength() &&
228 !memcmp(Name->getKeyData(), NameStr, NameLen))
232 ST->removeValueName(Name);
240 // Name is changing to something new.
241 Name = ST->createValueName(NameStr, NameLen, this);
245 /// takeName - transfer the name from V to this value, setting V's name to
246 /// empty. It is an error to call V->takeName(V).
247 void Value::takeName(Value *V) {
248 ValueSymbolTable *ST = 0;
249 // If this value has a name, drop it.
251 // Get the symtab this is in.
252 if (getSymTab(this, ST)) {
253 // We can't set a name on this value, but we need to clear V's name if
255 if (V->hasName()) V->setName(0, 0);
256 return; // Cannot set a name on this value (e.g. constant).
261 ST->removeValueName(Name);
266 // Now we know that this has no name.
268 // If V has no name either, we're done.
269 if (!V->hasName()) return;
271 // Get this's symtab if we didn't before.
273 if (getSymTab(this, ST)) {
276 return; // Cannot set a name on this value (e.g. constant).
280 // Get V's ST, this should always succed, because V has a name.
281 ValueSymbolTable *VST;
282 bool Failure = getSymTab(V, VST);
283 assert(!Failure && "V has a name, so it should have a ST!"); Failure=Failure;
285 // If these values are both in the same symtab, we can do this very fast.
286 // This works even if both values have no symtab yet.
291 Name->setValue(this);
295 // Otherwise, things are slightly more complex. Remove V's name from VST and
296 // then reinsert it into ST.
299 VST->removeValueName(V->Name);
302 Name->setValue(this);
305 ST->reinsertValue(this);
309 // uncheckedReplaceAllUsesWith - This is exactly the same as replaceAllUsesWith,
310 // except that it doesn't have all of the asserts. The asserts fail because we
311 // are half-way done resolving types, which causes some types to exist as two
312 // different Type*'s at the same time. This is a sledgehammer to work around
315 void Value::uncheckedReplaceAllUsesWith(Value *New) {
316 // Notify all ValueHandles (if present) that this value is going away.
318 ValueHandleBase::ValueIsRAUWd(this, New);
320 while (!use_empty()) {
322 // Must handle Constants specially, we cannot call replaceUsesOfWith on a
323 // constant because they are uniqued.
324 if (Constant *C = dyn_cast<Constant>(U.getUser())) {
325 if (!isa<GlobalValue>(C)) {
326 C->replaceUsesOfWithOnConstant(this, New, &U);
335 void Value::replaceAllUsesWith(Value *New) {
336 assert(New && "Value::replaceAllUsesWith(<null>) is invalid!");
337 assert(New != this && "this->replaceAllUsesWith(this) is NOT valid!");
338 assert(New->getType() == getType() &&
339 "replaceAllUses of value with new value of different type!");
341 uncheckedReplaceAllUsesWith(New);
344 Value *Value::stripPointerCasts() {
345 if (!isa<PointerType>(getType()))
349 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
350 if (!GEP->hasAllZeroIndices())
352 V = GEP->getPointerOperand();
353 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
354 V = cast<Operator>(V)->getOperand(0);
358 assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
362 Value *Value::getUnderlyingObject() {
363 if (!isa<PointerType>(getType()))
366 unsigned MaxLookup = 6;
368 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
369 V = GEP->getPointerOperand();
370 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
371 V = cast<Operator>(V)->getOperand(0);
375 assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
376 } while (--MaxLookup);
380 /// DoPHITranslation - If this value is a PHI node with CurBB as its parent,
381 /// return the value in the PHI node corresponding to PredBB. If not, return
382 /// ourself. This is useful if you want to know the value something has in a
383 /// predecessor block.
384 Value *Value::DoPHITranslation(const BasicBlock *CurBB,
385 const BasicBlock *PredBB) {
386 PHINode *PN = dyn_cast<PHINode>(this);
387 if (PN && PN->getParent() == CurBB)
388 return PN->getIncomingValueForBlock(PredBB);
392 LLVMContext &Value::getContext() const { return VTy->getContext(); }
394 //===----------------------------------------------------------------------===//
395 // ValueHandleBase Class
396 //===----------------------------------------------------------------------===//
398 /// ValueHandles - This map keeps track of all of the value handles that are
399 /// watching a Value*. The Value::HasValueHandle bit is used to know whether or
400 /// not a value has an entry in this map.
401 typedef DenseMap<Value*, ValueHandleBase*> ValueHandlesTy;
402 static ManagedStatic<ValueHandlesTy> ValueHandles;
403 static ManagedStatic<sys::SmartRWMutex<true> > ValueHandlesLock;
405 /// AddToExistingUseList - Add this ValueHandle to the use list for VP, where
406 /// List is known to point into the existing use list.
407 void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) {
408 assert(List && "Handle list is null?");
410 // Splice ourselves into the list.
415 Next->setPrevPtr(&Next);
416 assert(VP == Next->VP && "Added to wrong list?");
420 /// AddToUseList - Add this ValueHandle to the use list for VP.
421 void ValueHandleBase::AddToUseList() {
422 assert(VP && "Null pointer doesn't have a use list!");
423 if (VP->HasValueHandle) {
424 // If this value already has a ValueHandle, then it must be in the
425 // ValueHandles map already.
426 sys::SmartScopedReader<true> Reader(*ValueHandlesLock);
427 ValueHandleBase *&Entry = (*ValueHandles)[VP];
428 assert(Entry != 0 && "Value doesn't have any handles?");
429 AddToExistingUseList(&Entry);
433 // Ok, it doesn't have any handles yet, so we must insert it into the
434 // DenseMap. However, doing this insertion could cause the DenseMap to
435 // reallocate itself, which would invalidate all of the PrevP pointers that
436 // point into the old table. Handle this by checking for reallocation and
437 // updating the stale pointers only if needed.
438 sys::SmartScopedWriter<true> Writer(*ValueHandlesLock);
439 ValueHandlesTy &Handles = *ValueHandles;
440 const void *OldBucketPtr = Handles.getPointerIntoBucketsArray();
442 ValueHandleBase *&Entry = Handles[VP];
443 assert(Entry == 0 && "Value really did already have handles?");
444 AddToExistingUseList(&Entry);
445 VP->HasValueHandle = true;
447 // If reallocation didn't happen or if this was the first insertion, don't
449 if (Handles.isPointerIntoBucketsArray(OldBucketPtr) ||
450 Handles.size() == 1) {
454 // Okay, reallocation did happen. Fix the Prev Pointers.
455 for (ValueHandlesTy::iterator I = Handles.begin(), E = Handles.end();
457 assert(I->second && I->first == I->second->VP && "List invariant broken!");
458 I->second->setPrevPtr(&I->second);
462 /// RemoveFromUseList - Remove this ValueHandle from its current use list.
463 void ValueHandleBase::RemoveFromUseList() {
464 assert(VP && VP->HasValueHandle && "Pointer doesn't have a use list!");
466 // Unlink this from its use list.
467 ValueHandleBase **PrevPtr = getPrevPtr();
468 assert(*PrevPtr == this && "List invariant broken");
472 assert(Next->getPrevPtr() == &Next && "List invariant broken");
473 Next->setPrevPtr(PrevPtr);
477 // If the Next pointer was null, then it is possible that this was the last
478 // ValueHandle watching VP. If so, delete its entry from the ValueHandles
480 sys::SmartScopedWriter<true> Writer(*ValueHandlesLock);
481 ValueHandlesTy &Handles = *ValueHandles;
482 if (Handles.isPointerIntoBucketsArray(PrevPtr)) {
484 VP->HasValueHandle = false;
489 void ValueHandleBase::ValueIsDeleted(Value *V) {
490 assert(V->HasValueHandle && "Should only be called if ValueHandles present");
492 // Get the linked list base, which is guaranteed to exist since the
493 // HasValueHandle flag is set.
494 ValueHandlesLock->reader_acquire();
495 ValueHandleBase *Entry = (*ValueHandles)[V];
496 ValueHandlesLock->reader_release();
497 assert(Entry && "Value bit set but no entries exist");
500 // Advance pointer to avoid invalidation.
501 ValueHandleBase *ThisNode = Entry;
504 switch (ThisNode->getKind()) {
506 #ifndef NDEBUG // Only in -g mode...
507 cerr << "While deleting: " << *V->getType() << " %" << V->getNameStr()
510 llvm_unreachable("An asserting value handle still pointed to this"
513 // Weak just goes to null, which will unlink it from the list.
514 ThisNode->operator=(0);
517 // Forward to the subclass's implementation.
518 static_cast<CallbackVH*>(ThisNode)->deleted();
523 // All callbacks and weak references should be dropped by now.
524 assert(!V->HasValueHandle && "All references to V were not removed?");
528 void ValueHandleBase::ValueIsRAUWd(Value *Old, Value *New) {
529 assert(Old->HasValueHandle &&"Should only be called if ValueHandles present");
530 assert(Old != New && "Changing value into itself!");
532 // Get the linked list base, which is guaranteed to exist since the
533 // HasValueHandle flag is set.
534 ValueHandlesLock->reader_acquire();
535 ValueHandleBase *Entry = (*ValueHandles)[Old];
536 ValueHandlesLock->reader_release();
537 assert(Entry && "Value bit set but no entries exist");
540 // Advance pointer to avoid invalidation.
541 ValueHandleBase *ThisNode = Entry;
544 switch (ThisNode->getKind()) {
546 // Asserting handle does not follow RAUW implicitly.
549 // Weak goes to the new value, which will unlink it from Old's list.
550 ThisNode->operator=(New);
553 // Forward to the subclass's implementation.
554 static_cast<CallbackVH*>(ThisNode)->allUsesReplacedWith(New);
560 /// ~CallbackVH. Empty, but defined here to avoid emitting the vtable
562 CallbackVH::~CallbackVH() {}
565 //===----------------------------------------------------------------------===//
567 //===----------------------------------------------------------------------===//
569 // replaceUsesOfWith - Replaces all references to the "From" definition with
570 // references to the "To" definition.
572 void User::replaceUsesOfWith(Value *From, Value *To) {
573 if (From == To) return; // Duh what?
575 assert((!isa<Constant>(this) || isa<GlobalValue>(this)) &&
576 "Cannot call User::replaceUsesofWith on a constant!");
578 for (unsigned i = 0, E = getNumOperands(); i != E; ++i)
579 if (getOperand(i) == From) { // Is This operand is pointing to oldval?
580 // The side effects of this setOperand call include linking to
581 // "To", adding "this" to the uses list of To, and
582 // most importantly, removing "this" from the use list of "From".
583 setOperand(i, To); // Fix it now...