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/ADT/SmallString.h"
24 #include "llvm/Support/Debug.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/LeakDetector.h"
27 #include "llvm/Support/ManagedStatic.h"
28 #include "llvm/Support/ValueHandle.h"
29 #include "llvm/Support/raw_ostream.h"
30 #include "llvm/System/RWMutex.h"
31 #include "llvm/System/Threading.h"
32 #include "llvm/ADT/DenseMap.h"
36 //===----------------------------------------------------------------------===//
38 //===----------------------------------------------------------------------===//
40 static inline const Type *checkType(const Type *Ty) {
41 assert(Ty && "Value defined with a null type: Error!");
45 Value::Value(const Type *ty, unsigned scid)
46 : SubclassID(scid), HasValueHandle(0), SubclassOptionalData(0),
47 SubclassData(0), VTy(checkType(ty)),
49 if (isa<CallInst>(this) || isa<InvokeInst>(this))
50 assert((VTy->isFirstClassType() || VTy == Type::VoidTy ||
51 isa<OpaqueType>(ty) || VTy->getTypeID() == Type::StructTyID) &&
52 "invalid CallInst type!");
53 else if (!isa<Constant>(this) && !isa<BasicBlock>(this))
54 assert((VTy->isFirstClassType() || VTy == Type::VoidTy ||
55 isa<OpaqueType>(ty)) &&
56 "Cannot create non-first-class values except for constants!");
60 // Notify all ValueHandles (if present) that this value is going away.
62 ValueHandleBase::ValueIsDeleted(this);
64 #ifndef NDEBUG // Only in -g mode...
65 // Check to make sure that there are no uses of this value that are still
66 // around when the value is destroyed. If there are, then we have a dangling
67 // reference and something is wrong. This code is here to print out what is
68 // still being referenced. The value in question should be printed as
72 errs() << "While deleting: " << *VTy << " %" << getNameStr() << "\n";
73 for (use_iterator I = use_begin(), E = use_end(); I != E; ++I)
74 errs() << "Use still stuck around after Def is destroyed:"
78 assert(use_empty() && "Uses remain when a value is destroyed!");
80 // If this value is named, destroy the name. This should not be in a symtab
85 // There should be no uses of this object anymore, remove it.
86 LeakDetector::removeGarbageObject(this);
89 /// hasNUses - Return true if this Value has exactly N users.
91 bool Value::hasNUses(unsigned N) const {
92 use_const_iterator UI = use_begin(), E = use_end();
95 if (UI == E) return false; // Too few.
99 /// hasNUsesOrMore - Return true if this value has N users or more. This is
100 /// logically equivalent to getNumUses() >= N.
102 bool Value::hasNUsesOrMore(unsigned N) const {
103 use_const_iterator UI = use_begin(), E = use_end();
106 if (UI == E) return false; // Too few.
111 /// isUsedInBasicBlock - Return true if this value is used in the specified
113 bool Value::isUsedInBasicBlock(const BasicBlock *BB) const {
114 for (use_const_iterator I = use_begin(), E = use_end(); I != E; ++I) {
115 const Instruction *User = dyn_cast<Instruction>(*I);
116 if (User && User->getParent() == BB)
123 /// getNumUses - This method computes the number of uses of this Value. This
124 /// is a linear time operation. Use hasOneUse or hasNUses to check for specific
126 unsigned Value::getNumUses() const {
127 return (unsigned)std::distance(use_begin(), use_end());
130 static bool getSymTab(Value *V, ValueSymbolTable *&ST) {
132 if (Instruction *I = dyn_cast<Instruction>(V)) {
133 if (BasicBlock *P = I->getParent())
134 if (Function *PP = P->getParent())
135 ST = &PP->getValueSymbolTable();
136 } else if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
137 if (Function *P = BB->getParent())
138 ST = &P->getValueSymbolTable();
139 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
140 if (Module *P = GV->getParent())
141 ST = &P->getValueSymbolTable();
142 } else if (Argument *A = dyn_cast<Argument>(V)) {
143 if (Function *P = A->getParent())
144 ST = &P->getValueSymbolTable();
145 } else if (isa<MDString>(V))
148 assert(isa<Constant>(V) && "Unknown value type!");
149 return true; // no name is setable for this.
154 /// getNameStart - Return a pointer to a null terminated string for this name.
155 /// Note that names can have null characters within the string as well as at
156 /// their end. This always returns a non-null pointer.
157 const char *Value::getNameStart() const {
158 if (Name == 0) return "";
159 return Name->getKeyData();
162 /// getNameLen - Return the length of the string, correctly handling nul
163 /// characters embedded into them.
164 unsigned Value::getNameLen() const {
165 return Name ? Name->getKeyLength() : 0;
169 std::string Value::getNameStr() const {
170 return getName().str();
173 void Value::setName(const Twine &NewName) {
174 SmallString<32> NameData;
175 NewName.toVector(NameData);
177 const char *NameStr = NameData.data();
178 unsigned NameLen = NameData.size();
180 if (NameLen == 0 && !hasName()) return;
181 assert(getType() != Type::VoidTy && "Cannot assign a name to void values!");
183 // Get the symbol table to update for this object.
184 ValueSymbolTable *ST;
185 if (getSymTab(this, ST))
186 return; // Cannot set a name on this value (e.g. constant).
188 if (!ST) { // No symbol table to update? Just do the change.
190 // Free the name for this value.
197 // Name isn't changing?
198 if (NameLen == Name->getKeyLength() &&
199 !memcmp(Name->getKeyData(), NameStr, NameLen))
204 // NOTE: Could optimize for the case the name is shrinking to not deallocate
207 // Create the new name.
208 Name = ValueName::Create(NameStr, NameStr+NameLen);
209 Name->setValue(this);
213 // NOTE: Could optimize for the case the name is shrinking to not deallocate
216 // Name isn't changing?
217 if (NameLen == Name->getKeyLength() &&
218 !memcmp(Name->getKeyData(), NameStr, NameLen))
222 ST->removeValueName(Name);
230 // Name is changing to something new.
231 Name = ST->createValueName(StringRef(NameStr, NameLen), this);
235 /// takeName - transfer the name from V to this value, setting V's name to
236 /// empty. It is an error to call V->takeName(V).
237 void Value::takeName(Value *V) {
238 ValueSymbolTable *ST = 0;
239 // If this value has a name, drop it.
241 // Get the symtab this is in.
242 if (getSymTab(this, ST)) {
243 // We can't set a name on this value, but we need to clear V's name if
245 if (V->hasName()) V->setName("");
246 return; // Cannot set a name on this value (e.g. constant).
251 ST->removeValueName(Name);
256 // Now we know that this has no name.
258 // If V has no name either, we're done.
259 if (!V->hasName()) return;
261 // Get this's symtab if we didn't before.
263 if (getSymTab(this, ST)) {
266 return; // Cannot set a name on this value (e.g. constant).
270 // Get V's ST, this should always succed, because V has a name.
271 ValueSymbolTable *VST;
272 bool Failure = getSymTab(V, VST);
273 assert(!Failure && "V has a name, so it should have a ST!"); Failure=Failure;
275 // If these values are both in the same symtab, we can do this very fast.
276 // This works even if both values have no symtab yet.
281 Name->setValue(this);
285 // Otherwise, things are slightly more complex. Remove V's name from VST and
286 // then reinsert it into ST.
289 VST->removeValueName(V->Name);
292 Name->setValue(this);
295 ST->reinsertValue(this);
299 // uncheckedReplaceAllUsesWith - This is exactly the same as replaceAllUsesWith,
300 // except that it doesn't have all of the asserts. The asserts fail because we
301 // are half-way done resolving types, which causes some types to exist as two
302 // different Type*'s at the same time. This is a sledgehammer to work around
305 void Value::uncheckedReplaceAllUsesWith(Value *New) {
306 // Notify all ValueHandles (if present) that this value is going away.
308 ValueHandleBase::ValueIsRAUWd(this, New);
310 while (!use_empty()) {
312 // Must handle Constants specially, we cannot call replaceUsesOfWith on a
313 // constant because they are uniqued.
314 if (Constant *C = dyn_cast<Constant>(U.getUser())) {
315 if (!isa<GlobalValue>(C)) {
316 C->replaceUsesOfWithOnConstant(this, New, &U);
325 void Value::replaceAllUsesWith(Value *New) {
326 assert(New && "Value::replaceAllUsesWith(<null>) is invalid!");
327 assert(New != this && "this->replaceAllUsesWith(this) is NOT valid!");
328 assert(New->getType() == getType() &&
329 "replaceAllUses of value with new value of different type!");
331 uncheckedReplaceAllUsesWith(New);
334 Value *Value::stripPointerCasts() {
335 if (!isa<PointerType>(getType()))
339 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
340 if (!GEP->hasAllZeroIndices())
342 V = GEP->getPointerOperand();
343 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
344 V = cast<Operator>(V)->getOperand(0);
348 assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
352 Value *Value::getUnderlyingObject() {
353 if (!isa<PointerType>(getType()))
356 unsigned MaxLookup = 6;
358 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
359 V = GEP->getPointerOperand();
360 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
361 V = cast<Operator>(V)->getOperand(0);
365 assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
366 } while (--MaxLookup);
370 /// DoPHITranslation - If this value is a PHI node with CurBB as its parent,
371 /// return the value in the PHI node corresponding to PredBB. If not, return
372 /// ourself. This is useful if you want to know the value something has in a
373 /// predecessor block.
374 Value *Value::DoPHITranslation(const BasicBlock *CurBB,
375 const BasicBlock *PredBB) {
376 PHINode *PN = dyn_cast<PHINode>(this);
377 if (PN && PN->getParent() == CurBB)
378 return PN->getIncomingValueForBlock(PredBB);
382 LLVMContext &Value::getContext() const { return VTy->getContext(); }
384 //===----------------------------------------------------------------------===//
385 // ValueHandleBase Class
386 //===----------------------------------------------------------------------===//
388 /// ValueHandles - This map keeps track of all of the value handles that are
389 /// watching a Value*. The Value::HasValueHandle bit is used to know whether or
390 /// not a value has an entry in this map.
391 typedef DenseMap<Value*, ValueHandleBase*> ValueHandlesTy;
392 static ManagedStatic<ValueHandlesTy> ValueHandles;
393 static ManagedStatic<sys::SmartRWMutex<true> > ValueHandlesLock;
395 /// AddToExistingUseList - Add this ValueHandle to the use list for VP, where
396 /// List is known to point into the existing use list.
397 void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) {
398 assert(List && "Handle list is null?");
400 // Splice ourselves into the list.
405 Next->setPrevPtr(&Next);
406 assert(VP == Next->VP && "Added to wrong list?");
410 /// AddToUseList - Add this ValueHandle to the use list for VP.
411 void ValueHandleBase::AddToUseList() {
412 assert(VP && "Null pointer doesn't have a use list!");
413 if (VP->HasValueHandle) {
414 // If this value already has a ValueHandle, then it must be in the
415 // ValueHandles map already.
416 sys::SmartScopedReader<true> Reader(*ValueHandlesLock);
417 ValueHandleBase *&Entry = (*ValueHandles)[VP];
418 assert(Entry != 0 && "Value doesn't have any handles?");
419 AddToExistingUseList(&Entry);
423 // Ok, it doesn't have any handles yet, so we must insert it into the
424 // DenseMap. However, doing this insertion could cause the DenseMap to
425 // reallocate itself, which would invalidate all of the PrevP pointers that
426 // point into the old table. Handle this by checking for reallocation and
427 // updating the stale pointers only if needed.
428 sys::SmartScopedWriter<true> Writer(*ValueHandlesLock);
429 ValueHandlesTy &Handles = *ValueHandles;
430 const void *OldBucketPtr = Handles.getPointerIntoBucketsArray();
432 ValueHandleBase *&Entry = Handles[VP];
433 assert(Entry == 0 && "Value really did already have handles?");
434 AddToExistingUseList(&Entry);
435 VP->HasValueHandle = true;
437 // If reallocation didn't happen or if this was the first insertion, don't
439 if (Handles.isPointerIntoBucketsArray(OldBucketPtr) ||
440 Handles.size() == 1) {
444 // Okay, reallocation did happen. Fix the Prev Pointers.
445 for (ValueHandlesTy::iterator I = Handles.begin(), E = Handles.end();
447 assert(I->second && I->first == I->second->VP && "List invariant broken!");
448 I->second->setPrevPtr(&I->second);
452 /// RemoveFromUseList - Remove this ValueHandle from its current use list.
453 void ValueHandleBase::RemoveFromUseList() {
454 assert(VP && VP->HasValueHandle && "Pointer doesn't have a use list!");
456 // Unlink this from its use list.
457 ValueHandleBase **PrevPtr = getPrevPtr();
458 assert(*PrevPtr == this && "List invariant broken");
462 assert(Next->getPrevPtr() == &Next && "List invariant broken");
463 Next->setPrevPtr(PrevPtr);
467 // If the Next pointer was null, then it is possible that this was the last
468 // ValueHandle watching VP. If so, delete its entry from the ValueHandles
470 sys::SmartScopedWriter<true> Writer(*ValueHandlesLock);
471 ValueHandlesTy &Handles = *ValueHandles;
472 if (Handles.isPointerIntoBucketsArray(PrevPtr)) {
474 VP->HasValueHandle = false;
479 void ValueHandleBase::ValueIsDeleted(Value *V) {
480 assert(V->HasValueHandle && "Should only be called if ValueHandles present");
482 // Get the linked list base, which is guaranteed to exist since the
483 // HasValueHandle flag is set.
484 ValueHandlesLock->reader_acquire();
485 ValueHandleBase *Entry = (*ValueHandles)[V];
486 ValueHandlesLock->reader_release();
487 assert(Entry && "Value bit set but no entries exist");
490 // Advance pointer to avoid invalidation.
491 ValueHandleBase *ThisNode = Entry;
494 switch (ThisNode->getKind()) {
496 #ifndef NDEBUG // Only in -g mode...
497 errs() << "While deleting: " << *V->getType() << " %" << V->getNameStr()
500 llvm_unreachable("An asserting value handle still pointed to this"
503 // Weak just goes to null, which will unlink it from the list.
504 ThisNode->operator=(0);
507 // Forward to the subclass's implementation.
508 static_cast<CallbackVH*>(ThisNode)->deleted();
513 // All callbacks and weak references should be dropped by now.
514 assert(!V->HasValueHandle && "All references to V were not removed?");
518 void ValueHandleBase::ValueIsRAUWd(Value *Old, Value *New) {
519 assert(Old->HasValueHandle &&"Should only be called if ValueHandles present");
520 assert(Old != New && "Changing value into itself!");
522 // Get the linked list base, which is guaranteed to exist since the
523 // HasValueHandle flag is set.
524 ValueHandlesLock->reader_acquire();
525 ValueHandleBase *Entry = (*ValueHandles)[Old];
526 ValueHandlesLock->reader_release();
527 assert(Entry && "Value bit set but no entries exist");
530 // Advance pointer to avoid invalidation.
531 ValueHandleBase *ThisNode = Entry;
534 switch (ThisNode->getKind()) {
536 // Asserting handle does not follow RAUW implicitly.
539 // Weak goes to the new value, which will unlink it from Old's list.
540 ThisNode->operator=(New);
543 // Forward to the subclass's implementation.
544 static_cast<CallbackVH*>(ThisNode)->allUsesReplacedWith(New);
550 /// ~CallbackVH. Empty, but defined here to avoid emitting the vtable
552 CallbackVH::~CallbackVH() {}
555 //===----------------------------------------------------------------------===//
557 //===----------------------------------------------------------------------===//
559 // replaceUsesOfWith - Replaces all references to the "From" definition with
560 // references to the "To" definition.
562 void User::replaceUsesOfWith(Value *From, Value *To) {
563 if (From == To) return; // Duh what?
565 assert((!isa<Constant>(this) || isa<GlobalValue>(this)) &&
566 "Cannot call User::replaceUsesofWith on a constant!");
568 for (unsigned i = 0, E = getNumOperands(); i != E; ++i)
569 if (getOperand(i) == From) { // Is This operand is pointing to oldval?
570 // The side effects of this setOperand call include linking to
571 // "To", adding "this" to the uses list of To, and
572 // most importantly, removing "this" from the use list of "From".
573 setOperand(i, To); // Fix it now...