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 "LLVMContextImpl.h"
15 #include "llvm/Constant.h"
16 #include "llvm/Constants.h"
17 #include "llvm/DerivedTypes.h"
18 #include "llvm/InstrTypes.h"
19 #include "llvm/Instructions.h"
20 #include "llvm/Operator.h"
21 #include "llvm/Module.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/ADT/DenseMap.h"
33 //===----------------------------------------------------------------------===//
35 //===----------------------------------------------------------------------===//
37 static inline const Type *checkType(const Type *Ty) {
38 assert(Ty && "Value defined with a null type: Error!");
42 Value::Value(const Type *ty, unsigned scid)
43 : SubclassID(scid), HasValueHandle(0),
44 SubclassOptionalData(0), SubclassData(0), VTy(checkType(ty)),
46 if (isa<CallInst>(this) || isa<InvokeInst>(this))
47 assert((VTy->isFirstClassType() ||
48 VTy == Type::getVoidTy(ty->getContext()) ||
49 isa<OpaqueType>(ty) || VTy->getTypeID() == Type::StructTyID) &&
50 "invalid CallInst type!");
51 else if (!isa<Constant>(this) && !isa<BasicBlock>(this))
52 assert((VTy->isFirstClassType() ||
53 VTy == Type::getVoidTy(ty->getContext()) ||
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 dbgs() << "While deleting: " << *VTy << " %" << getNameStr() << "\n";
72 for (use_iterator I = use_begin(), E = use_end(); I != E; ++I)
73 dbgs() << "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 (NamedMDNode *N = dyn_cast<NamedMDNode>(V)) {
145 if (Module *P = N->getParent()) {
146 ST = &P->getValueSymbolTable();
148 } else if (isa<MDString>(V))
151 assert(isa<Constant>(V) && "Unknown value type!");
152 return true; // no name is setable for this.
157 StringRef Value::getName() const {
158 // Make sure the empty string is still a C string. For historical reasons,
159 // some clients want to call .data() on the result and expect it to be null
161 if (!Name) return StringRef("", 0);
162 return Name->getKey();
165 std::string Value::getNameStr() const {
166 return getName().str();
169 void Value::setName(const Twine &NewName) {
170 // Fast path for common IRBuilder case of setName("") when there is no name.
171 if (NewName.isTriviallyEmpty() && !hasName())
174 SmallString<256> NameData;
175 NewName.toVector(NameData);
177 const char *NameStr = NameData.data();
178 unsigned NameLen = NameData.size();
180 // Name isn't changing?
181 if (getName() == StringRef(NameStr, NameLen))
184 assert(getType() != Type::getVoidTy(getContext()) &&
185 "Cannot assign a name to void values!");
187 // Get the symbol table to update for this object.
188 ValueSymbolTable *ST;
189 if (getSymTab(this, ST))
190 return; // Cannot set a name on this value (e.g. constant).
192 if (!ST) { // No symbol table to update? Just do the change.
194 // Free the name for this value.
203 // NOTE: Could optimize for the case the name is shrinking to not deallocate
206 // Create the new name.
207 Name = ValueName::Create(NameStr, NameStr+NameLen);
208 Name->setValue(this);
212 // NOTE: Could optimize for the case the name is shrinking to not deallocate
216 ST->removeValueName(Name);
224 // Name is changing to something new.
225 Name = ST->createValueName(StringRef(NameStr, NameLen), this);
229 /// takeName - transfer the name from V to this value, setting V's name to
230 /// empty. It is an error to call V->takeName(V).
231 void Value::takeName(Value *V) {
232 ValueSymbolTable *ST = 0;
233 // If this value has a name, drop it.
235 // Get the symtab this is in.
236 if (getSymTab(this, ST)) {
237 // We can't set a name on this value, but we need to clear V's name if
239 if (V->hasName()) V->setName("");
240 return; // Cannot set a name on this value (e.g. constant).
245 ST->removeValueName(Name);
250 // Now we know that this has no name.
252 // If V has no name either, we're done.
253 if (!V->hasName()) return;
255 // Get this's symtab if we didn't before.
257 if (getSymTab(this, ST)) {
260 return; // Cannot set a name on this value (e.g. constant).
264 // Get V's ST, this should always succed, because V has a name.
265 ValueSymbolTable *VST;
266 bool Failure = getSymTab(V, VST);
267 assert(!Failure && "V has a name, so it should have a ST!"); Failure=Failure;
269 // If these values are both in the same symtab, we can do this very fast.
270 // This works even if both values have no symtab yet.
275 Name->setValue(this);
279 // Otherwise, things are slightly more complex. Remove V's name from VST and
280 // then reinsert it into ST.
283 VST->removeValueName(V->Name);
286 Name->setValue(this);
289 ST->reinsertValue(this);
293 // uncheckedReplaceAllUsesWith - This is exactly the same as replaceAllUsesWith,
294 // except that it doesn't have all of the asserts. The asserts fail because we
295 // are half-way done resolving types, which causes some types to exist as two
296 // different Type*'s at the same time. This is a sledgehammer to work around
299 void Value::uncheckedReplaceAllUsesWith(Value *New) {
300 // Notify all ValueHandles (if present) that this value is going away.
302 ValueHandleBase::ValueIsRAUWd(this, New);
304 while (!use_empty()) {
306 // Must handle Constants specially, we cannot call replaceUsesOfWith on a
307 // constant because they are uniqued.
308 if (Constant *C = dyn_cast<Constant>(U.getUser())) {
309 if (!isa<GlobalValue>(C)) {
310 C->replaceUsesOfWithOnConstant(this, New, &U);
319 void Value::replaceAllUsesWith(Value *New) {
320 assert(New && "Value::replaceAllUsesWith(<null>) is invalid!");
321 assert(New != this && "this->replaceAllUsesWith(this) is NOT valid!");
322 assert(New->getType() == getType() &&
323 "replaceAllUses of value with new value of different type!");
325 uncheckedReplaceAllUsesWith(New);
328 Value *Value::stripPointerCasts() {
329 if (!isa<PointerType>(getType()))
333 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
334 if (!GEP->hasAllZeroIndices())
336 V = GEP->getPointerOperand();
337 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
338 V = cast<Operator>(V)->getOperand(0);
339 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
340 if (GA->mayBeOverridden())
342 V = GA->getAliasee();
346 assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
350 Value *Value::getUnderlyingObject() {
351 if (!isa<PointerType>(getType()))
354 unsigned MaxLookup = 6;
356 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
357 V = GEP->getPointerOperand();
358 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
359 V = cast<Operator>(V)->getOperand(0);
360 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
361 if (GA->mayBeOverridden())
363 V = GA->getAliasee();
367 assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
368 } while (--MaxLookup);
372 /// DoPHITranslation - If this value is a PHI node with CurBB as its parent,
373 /// return the value in the PHI node corresponding to PredBB. If not, return
374 /// ourself. This is useful if you want to know the value something has in a
375 /// predecessor block.
376 Value *Value::DoPHITranslation(const BasicBlock *CurBB,
377 const BasicBlock *PredBB) {
378 PHINode *PN = dyn_cast<PHINode>(this);
379 if (PN && PN->getParent() == CurBB)
380 return PN->getIncomingValueForBlock(PredBB);
384 LLVMContext &Value::getContext() const { return VTy->getContext(); }
386 //===----------------------------------------------------------------------===//
387 // ValueHandleBase Class
388 //===----------------------------------------------------------------------===//
390 /// AddToExistingUseList - Add this ValueHandle to the use list for VP, where
391 /// List is known to point into the existing use list.
392 void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) {
393 assert(List && "Handle list is null?");
395 // Splice ourselves into the list.
400 Next->setPrevPtr(&Next);
401 assert(VP == Next->VP && "Added to wrong list?");
405 void ValueHandleBase::AddToExistingUseListAfter(ValueHandleBase *List) {
406 assert(List && "Must insert after existing node");
409 setPrevPtr(&List->Next);
412 Next->setPrevPtr(&Next);
415 /// AddToUseList - Add this ValueHandle to the use list for VP.
416 void ValueHandleBase::AddToUseList() {
417 assert(VP && "Null pointer doesn't have a use list!");
419 LLVMContextImpl *pImpl = VP->getContext().pImpl;
421 if (VP->HasValueHandle) {
422 // If this value already has a ValueHandle, then it must be in the
423 // ValueHandles map already.
424 ValueHandleBase *&Entry = pImpl->ValueHandles[VP];
425 assert(Entry != 0 && "Value doesn't have any handles?");
426 AddToExistingUseList(&Entry);
430 // Ok, it doesn't have any handles yet, so we must insert it into the
431 // DenseMap. However, doing this insertion could cause the DenseMap to
432 // reallocate itself, which would invalidate all of the PrevP pointers that
433 // point into the old table. Handle this by checking for reallocation and
434 // updating the stale pointers only if needed.
435 DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
436 const void *OldBucketPtr = Handles.getPointerIntoBucketsArray();
438 ValueHandleBase *&Entry = Handles[VP];
439 assert(Entry == 0 && "Value really did already have handles?");
440 AddToExistingUseList(&Entry);
441 VP->HasValueHandle = true;
443 // If reallocation didn't happen or if this was the first insertion, don't
445 if (Handles.isPointerIntoBucketsArray(OldBucketPtr) ||
446 Handles.size() == 1) {
450 // Okay, reallocation did happen. Fix the Prev Pointers.
451 for (DenseMap<Value*, ValueHandleBase*>::iterator I = Handles.begin(),
452 E = Handles.end(); I != E; ++I) {
453 assert(I->second && I->first == I->second->VP && "List invariant broken!");
454 I->second->setPrevPtr(&I->second);
458 /// RemoveFromUseList - Remove this ValueHandle from its current use list.
459 void ValueHandleBase::RemoveFromUseList() {
460 assert(VP && VP->HasValueHandle && "Pointer doesn't have a use list!");
462 // Unlink this from its use list.
463 ValueHandleBase **PrevPtr = getPrevPtr();
464 assert(*PrevPtr == this && "List invariant broken");
468 assert(Next->getPrevPtr() == &Next && "List invariant broken");
469 Next->setPrevPtr(PrevPtr);
473 // If the Next pointer was null, then it is possible that this was the last
474 // ValueHandle watching VP. If so, delete its entry from the ValueHandles
476 LLVMContextImpl *pImpl = VP->getContext().pImpl;
477 DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
478 if (Handles.isPointerIntoBucketsArray(PrevPtr)) {
480 VP->HasValueHandle = false;
485 void ValueHandleBase::ValueIsDeleted(Value *V) {
486 assert(V->HasValueHandle && "Should only be called if ValueHandles present");
488 // Get the linked list base, which is guaranteed to exist since the
489 // HasValueHandle flag is set.
490 LLVMContextImpl *pImpl = V->getContext().pImpl;
491 ValueHandleBase *Entry = pImpl->ValueHandles[V];
492 assert(Entry && "Value bit set but no entries exist");
494 // We use a local ValueHandleBase as an iterator so that
495 // ValueHandles can add and remove themselves from the list without
496 // breaking our iteration. This is not really an AssertingVH; we
497 // just have to give ValueHandleBase some kind.
498 for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) {
499 Iterator.RemoveFromUseList();
500 Iterator.AddToExistingUseListAfter(Entry);
501 assert(Entry->Next == &Iterator && "Loop invariant broken.");
503 switch (Entry->getKind()) {
507 // Mark that this value has been deleted by setting it to an invalid Value
509 Entry->operator=(DenseMapInfo<Value *>::getTombstoneKey());
512 // Weak just goes to null, which will unlink it from the list.
516 // Forward to the subclass's implementation.
517 static_cast<CallbackVH*>(Entry)->deleted();
522 // All callbacks, weak references, and assertingVHs should be dropped by now.
523 if (V->HasValueHandle) {
524 #ifndef NDEBUG // Only in +Asserts mode...
525 dbgs() << "While deleting: " << *V->getType() << " %" << V->getNameStr()
527 if (pImpl->ValueHandles[V]->getKind() == Assert)
528 llvm_unreachable("An asserting value handle still pointed to this"
532 llvm_unreachable("All references to V were not removed?");
537 void ValueHandleBase::ValueIsRAUWd(Value *Old, Value *New) {
538 assert(Old->HasValueHandle &&"Should only be called if ValueHandles present");
539 assert(Old != New && "Changing value into itself!");
541 // Get the linked list base, which is guaranteed to exist since the
542 // HasValueHandle flag is set.
543 LLVMContextImpl *pImpl = Old->getContext().pImpl;
544 ValueHandleBase *Entry = pImpl->ValueHandles[Old];
546 assert(Entry && "Value bit set but no entries exist");
548 // We use a local ValueHandleBase as an iterator so that
549 // ValueHandles can add and remove themselves from the list without
550 // breaking our iteration. This is not really an AssertingVH; we
551 // just have to give ValueHandleBase some kind.
552 for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) {
553 Iterator.RemoveFromUseList();
554 Iterator.AddToExistingUseListAfter(Entry);
555 assert(Entry->Next == &Iterator && "Loop invariant broken.");
557 switch (Entry->getKind()) {
559 // Asserting handle does not follow RAUW implicitly.
562 // Tracking goes to new value like a WeakVH. Note that this may make it
563 // something incompatible with its templated type. We don't want to have a
564 // virtual (or inline) interface to handle this though, so instead we make
565 // the TrackingVH accessors guarantee that a client never sees this value.
569 // Weak goes to the new value, which will unlink it from Old's list.
570 Entry->operator=(New);
573 // Forward to the subclass's implementation.
574 static_cast<CallbackVH*>(Entry)->allUsesReplacedWith(New);
580 /// ~CallbackVH. Empty, but defined here to avoid emitting the vtable
582 CallbackVH::~CallbackVH() {}
585 //===----------------------------------------------------------------------===//
587 //===----------------------------------------------------------------------===//
589 // replaceUsesOfWith - Replaces all references to the "From" definition with
590 // references to the "To" definition.
592 void User::replaceUsesOfWith(Value *From, Value *To) {
593 if (From == To) return; // Duh what?
595 assert((!isa<Constant>(this) || isa<GlobalValue>(this)) &&
596 "Cannot call User::replaceUsesOfWith on a constant!");
598 for (unsigned i = 0, E = getNumOperands(); i != E; ++i)
599 if (getOperand(i) == From) { // Is This operand is pointing to oldval?
600 // The side effects of this setOperand call include linking to
601 // "To", adding "this" to the uses list of To, and
602 // most importantly, removing "this" from the use list of "From".
603 setOperand(i, To); // Fix it now...