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/Metadata.h"
23 #include "llvm/ValueSymbolTable.h"
24 #include "llvm/ADT/SmallString.h"
25 #include "llvm/Support/Debug.h"
26 #include "llvm/Support/ErrorHandling.h"
27 #include "llvm/Support/LeakDetector.h"
28 #include "llvm/Support/ManagedStatic.h"
29 #include "llvm/Support/ValueHandle.h"
30 #include "llvm/Support/raw_ostream.h"
31 #include "llvm/System/RWMutex.h"
32 #include "llvm/System/Threading.h"
33 #include "llvm/ADT/DenseMap.h"
37 //===----------------------------------------------------------------------===//
39 //===----------------------------------------------------------------------===//
41 static inline const Type *checkType(const Type *Ty) {
42 assert(Ty && "Value defined with a null type: Error!");
46 Value::Value(const Type *ty, unsigned scid)
47 : SubclassID(scid), HasValueHandle(0), SubclassOptionalData(0),
48 SubclassData(0), VTy(checkType(ty)),
50 if (isa<CallInst>(this) || isa<InvokeInst>(this))
51 assert((VTy->isFirstClassType() ||
52 VTy == Type::getVoidTy(ty->getContext()) ||
53 isa<OpaqueType>(ty) || VTy->getTypeID() == Type::StructTyID) &&
54 "invalid CallInst type!");
55 else if (!isa<Constant>(this) && !isa<BasicBlock>(this))
56 assert((VTy->isFirstClassType() ||
57 VTy == Type::getVoidTy(ty->getContext()) ||
58 isa<OpaqueType>(ty)) &&
59 "Cannot create non-first-class values except for constants!");
63 // Notify all ValueHandles (if present) that this value is going away.
65 ValueHandleBase::ValueIsDeleted(this);
67 #ifndef NDEBUG // Only in -g mode...
68 // Check to make sure that there are no uses of this value that are still
69 // around when the value is destroyed. If there are, then we have a dangling
70 // reference and something is wrong. This code is here to print out what is
71 // still being referenced. The value in question should be printed as
75 errs() << "While deleting: " << *VTy << " %" << getNameStr() << "\n";
76 for (use_iterator I = use_begin(), E = use_end(); I != E; ++I)
77 errs() << "Use still stuck around after Def is destroyed:"
81 assert(use_empty() && "Uses remain when a value is destroyed!");
83 // If this value is named, destroy the name. This should not be in a symtab
88 // There should be no uses of this object anymore, remove it.
89 LeakDetector::removeGarbageObject(this);
92 /// hasNUses - Return true if this Value has exactly N users.
94 bool Value::hasNUses(unsigned N) const {
95 use_const_iterator UI = use_begin(), E = use_end();
98 if (UI == E) return false; // Too few.
102 /// hasNUsesOrMore - Return true if this value has N users or more. This is
103 /// logically equivalent to getNumUses() >= N.
105 bool Value::hasNUsesOrMore(unsigned N) const {
106 use_const_iterator UI = use_begin(), E = use_end();
109 if (UI == E) return false; // Too few.
114 /// isUsedInBasicBlock - Return true if this value is used in the specified
116 bool Value::isUsedInBasicBlock(const BasicBlock *BB) const {
117 for (use_const_iterator I = use_begin(), E = use_end(); I != E; ++I) {
118 const Instruction *User = dyn_cast<Instruction>(*I);
119 if (User && User->getParent() == BB)
126 /// getNumUses - This method computes the number of uses of this Value. This
127 /// is a linear time operation. Use hasOneUse or hasNUses to check for specific
129 unsigned Value::getNumUses() const {
130 return (unsigned)std::distance(use_begin(), use_end());
133 static bool getSymTab(Value *V, ValueSymbolTable *&ST) {
135 if (Instruction *I = dyn_cast<Instruction>(V)) {
136 if (BasicBlock *P = I->getParent())
137 if (Function *PP = P->getParent())
138 ST = &PP->getValueSymbolTable();
139 } else if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
140 if (Function *P = BB->getParent())
141 ST = &P->getValueSymbolTable();
142 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
143 if (Module *P = GV->getParent())
144 ST = &P->getValueSymbolTable();
145 } else if (Argument *A = dyn_cast<Argument>(V)) {
146 if (Function *P = A->getParent())
147 ST = &P->getValueSymbolTable();
148 } else if (NamedMDNode *N = dyn_cast<NamedMDNode>(V)) {
149 if (Module *P = N->getParent()) {
150 ST = &P->getValueSymbolTable();
152 } else if (isa<MDString>(V))
155 assert(isa<Constant>(V) && "Unknown value type!");
156 return true; // no name is setable for this.
161 StringRef Value::getName() const {
162 // Make sure the empty string is still a C string. For historical reasons,
163 // some clients want to call .data() on the result and expect it to be null
165 if (!Name) return StringRef("", 0);
166 return Name->getKey();
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 // 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);
342 assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
346 Value *Value::getUnderlyingObject() {
347 if (!isa<PointerType>(getType()))
350 unsigned MaxLookup = 6;
352 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
353 V = GEP->getPointerOperand();
354 } else if (Operator::getOpcode(V) == Instruction::BitCast) {
355 V = cast<Operator>(V)->getOperand(0);
359 assert(isa<PointerType>(V->getType()) && "Unexpected operand type!");
360 } while (--MaxLookup);
364 /// DoPHITranslation - If this value is a PHI node with CurBB as its parent,
365 /// return the value in the PHI node corresponding to PredBB. If not, return
366 /// ourself. This is useful if you want to know the value something has in a
367 /// predecessor block.
368 Value *Value::DoPHITranslation(const BasicBlock *CurBB,
369 const BasicBlock *PredBB) {
370 PHINode *PN = dyn_cast<PHINode>(this);
371 if (PN && PN->getParent() == CurBB)
372 return PN->getIncomingValueForBlock(PredBB);
376 LLVMContext &Value::getContext() const { return VTy->getContext(); }
378 //===----------------------------------------------------------------------===//
379 // ValueHandleBase Class
380 //===----------------------------------------------------------------------===//
382 /// AddToExistingUseList - Add this ValueHandle to the use list for VP, where
383 /// List is known to point into the existing use list.
384 void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) {
385 assert(List && "Handle list is null?");
387 // Splice ourselves into the list.
392 Next->setPrevPtr(&Next);
393 assert(VP == Next->VP && "Added to wrong list?");
397 /// AddToUseList - Add this ValueHandle to the use list for VP.
398 void ValueHandleBase::AddToUseList() {
399 assert(VP && "Null pointer doesn't have a use list!");
401 LLVMContextImpl *pImpl = VP->getContext().pImpl;
403 if (VP->HasValueHandle) {
404 // If this value already has a ValueHandle, then it must be in the
405 // ValueHandles map already.
406 ValueHandleBase *&Entry = pImpl->ValueHandles[VP];
407 assert(Entry != 0 && "Value doesn't have any handles?");
408 AddToExistingUseList(&Entry);
412 // Ok, it doesn't have any handles yet, so we must insert it into the
413 // DenseMap. However, doing this insertion could cause the DenseMap to
414 // reallocate itself, which would invalidate all of the PrevP pointers that
415 // point into the old table. Handle this by checking for reallocation and
416 // updating the stale pointers only if needed.
417 DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
418 const void *OldBucketPtr = Handles.getPointerIntoBucketsArray();
420 ValueHandleBase *&Entry = Handles[VP];
421 assert(Entry == 0 && "Value really did already have handles?");
422 AddToExistingUseList(&Entry);
423 VP->HasValueHandle = true;
425 // If reallocation didn't happen or if this was the first insertion, don't
427 if (Handles.isPointerIntoBucketsArray(OldBucketPtr) ||
428 Handles.size() == 1) {
432 // Okay, reallocation did happen. Fix the Prev Pointers.
433 for (DenseMap<Value*, ValueHandleBase*>::iterator I = Handles.begin(),
434 E = Handles.end(); I != E; ++I) {
435 assert(I->second && I->first == I->second->VP && "List invariant broken!");
436 I->second->setPrevPtr(&I->second);
440 /// RemoveFromUseList - Remove this ValueHandle from its current use list.
441 void ValueHandleBase::RemoveFromUseList() {
442 assert(VP && VP->HasValueHandle && "Pointer doesn't have a use list!");
444 // Unlink this from its use list.
445 ValueHandleBase **PrevPtr = getPrevPtr();
446 assert(*PrevPtr == this && "List invariant broken");
450 assert(Next->getPrevPtr() == &Next && "List invariant broken");
451 Next->setPrevPtr(PrevPtr);
455 // If the Next pointer was null, then it is possible that this was the last
456 // ValueHandle watching VP. If so, delete its entry from the ValueHandles
458 LLVMContextImpl *pImpl = VP->getContext().pImpl;
459 DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
460 if (Handles.isPointerIntoBucketsArray(PrevPtr)) {
462 VP->HasValueHandle = false;
467 void ValueHandleBase::ValueIsDeleted(Value *V) {
468 assert(V->HasValueHandle && "Should only be called if ValueHandles present");
470 // Get the linked list base, which is guaranteed to exist since the
471 // HasValueHandle flag is set.
472 LLVMContextImpl *pImpl = V->getContext().pImpl;
473 ValueHandleBase *Entry = pImpl->ValueHandles[V];
474 assert(Entry && "Value bit set but no entries exist");
477 // Advance pointer to avoid invalidation.
478 ValueHandleBase *ThisNode = Entry;
481 switch (ThisNode->getKind()) {
483 #ifndef NDEBUG // Only in -g mode...
484 errs() << "While deleting: " << *V->getType() << " %" << V->getNameStr()
487 llvm_unreachable("An asserting value handle still pointed to this"
490 // Weak just goes to null, which will unlink it from the list.
491 ThisNode->operator=(0);
494 // Forward to the subclass's implementation.
495 static_cast<CallbackVH*>(ThisNode)->deleted();
500 // All callbacks and weak references should be dropped by now.
501 assert(!V->HasValueHandle && "All references to V were not removed?");
505 void ValueHandleBase::ValueIsRAUWd(Value *Old, Value *New) {
506 assert(Old->HasValueHandle &&"Should only be called if ValueHandles present");
507 assert(Old != New && "Changing value into itself!");
509 // Get the linked list base, which is guaranteed to exist since the
510 // HasValueHandle flag is set.
511 LLVMContextImpl *pImpl = Old->getContext().pImpl;
512 ValueHandleBase *Entry = pImpl->ValueHandles[Old];
514 assert(Entry && "Value bit set but no entries exist");
517 // Advance pointer to avoid invalidation.
518 ValueHandleBase *ThisNode = Entry;
521 switch (ThisNode->getKind()) {
523 // Asserting handle does not follow RAUW implicitly.
526 // Weak goes to the new value, which will unlink it from Old's list.
527 ThisNode->operator=(New);
530 // Forward to the subclass's implementation.
531 static_cast<CallbackVH*>(ThisNode)->allUsesReplacedWith(New);
537 /// ~CallbackVH. Empty, but defined here to avoid emitting the vtable
539 CallbackVH::~CallbackVH() {}
542 //===----------------------------------------------------------------------===//
544 //===----------------------------------------------------------------------===//
546 // replaceUsesOfWith - Replaces all references to the "From" definition with
547 // references to the "To" definition.
549 void User::replaceUsesOfWith(Value *From, Value *To) {
550 if (From == To) return; // Duh what?
552 assert((!isa<Constant>(this) || isa<GlobalValue>(this)) &&
553 "Cannot call User::replaceUsesOfWith on a constant!");
555 for (unsigned i = 0, E = getNumOperands(); i != E; ++i)
556 if (getOperand(i) == From) { // Is This operand is pointing to oldval?
557 // The side effects of this setOperand call include linking to
558 // "To", adding "this" to the uses list of To, and
559 // most importantly, removing "this" from the use list of "From".
560 setOperand(i, To); // Fix it now...