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/IR/Value.h"
15 #include "LLVMContextImpl.h"
16 #include "llvm/ADT/DenseMap.h"
17 #include "llvm/ADT/SmallString.h"
18 #include "llvm/IR/CallSite.h"
19 #include "llvm/IR/Constant.h"
20 #include "llvm/IR/Constants.h"
21 #include "llvm/IR/DataLayout.h"
22 #include "llvm/IR/DerivedTypes.h"
23 #include "llvm/IR/GetElementPtrTypeIterator.h"
24 #include "llvm/IR/InstrTypes.h"
25 #include "llvm/IR/Instructions.h"
26 #include "llvm/IR/IntrinsicInst.h"
27 #include "llvm/IR/Module.h"
28 #include "llvm/IR/Operator.h"
29 #include "llvm/IR/Statepoint.h"
30 #include "llvm/IR/ValueHandle.h"
31 #include "llvm/IR/ValueSymbolTable.h"
32 #include "llvm/Support/Debug.h"
33 #include "llvm/Support/ErrorHandling.h"
34 #include "llvm/Support/ManagedStatic.h"
35 #include "llvm/Support/raw_ostream.h"
39 //===----------------------------------------------------------------------===//
41 //===----------------------------------------------------------------------===//
43 static inline Type *checkType(Type *Ty) {
44 assert(Ty && "Value defined with a null type: Error!");
48 Value::Value(Type *ty, unsigned scid)
49 : VTy(checkType(ty)), UseList(nullptr), SubclassID(scid),
50 HasValueHandle(0), SubclassOptionalData(0), SubclassData(0),
51 NumOperands(0), IsUsedByMD(false), HasName(false) {
52 // FIXME: Why isn't this in the subclass gunk??
53 // Note, we cannot call isa<CallInst> before the CallInst has been
55 if (SubclassID == Instruction::Call || SubclassID == Instruction::Invoke)
56 assert((VTy->isFirstClassType() || VTy->isVoidTy() || VTy->isStructTy()) &&
57 "invalid CallInst type!");
58 else if (SubclassID != BasicBlockVal &&
59 (SubclassID < ConstantFirstVal || SubclassID > ConstantLastVal))
60 assert((VTy->isFirstClassType() || VTy->isVoidTy()) &&
61 "Cannot create non-first-class values except for constants!");
65 // Notify all ValueHandles (if present) that this value is going away.
67 ValueHandleBase::ValueIsDeleted(this);
68 if (isUsedByMetadata())
69 ValueAsMetadata::handleDeletion(this);
71 #ifndef NDEBUG // Only in -g mode...
72 // Check to make sure that there are no uses of this value that are still
73 // around when the value is destroyed. If there are, then we have a dangling
74 // reference and something is wrong. This code is here to print out where
75 // the value is still being referenced.
78 dbgs() << "While deleting: " << *VTy << " %" << getName() << "\n";
79 for (auto *U : users())
80 dbgs() << "Use still stuck around after Def is destroyed:" << *U << "\n";
83 assert(use_empty() && "Uses remain when a value is destroyed!");
85 // If this value is named, destroy the name. This should not be in a symtab
90 void Value::destroyValueName() {
91 ValueName *Name = getValueName();
94 setValueName(nullptr);
97 bool Value::hasNUses(unsigned N) const {
98 const_use_iterator UI = use_begin(), E = use_end();
101 if (UI == E) return false; // Too few.
105 bool Value::hasNUsesOrMore(unsigned N) const {
106 const_use_iterator UI = use_begin(), E = use_end();
109 if (UI == E) return false; // Too few.
114 bool Value::isUsedInBasicBlock(const BasicBlock *BB) const {
115 // This can be computed either by scanning the instructions in BB, or by
116 // scanning the use list of this Value. Both lists can be very long, but
117 // usually one is quite short.
119 // Scan both lists simultaneously until one is exhausted. This limits the
120 // search to the shorter list.
121 BasicBlock::const_iterator BI = BB->begin(), BE = BB->end();
122 const_user_iterator UI = user_begin(), UE = user_end();
123 for (; BI != BE && UI != UE; ++BI, ++UI) {
124 // Scan basic block: Check if this Value is used by the instruction at BI.
125 if (std::find(BI->op_begin(), BI->op_end(), this) != BI->op_end())
127 // Scan use list: Check if the use at UI is in BB.
128 const Instruction *User = dyn_cast<Instruction>(*UI);
129 if (User && User->getParent() == BB)
135 unsigned Value::getNumUses() const {
136 return (unsigned)std::distance(use_begin(), use_end());
139 static bool getSymTab(Value *V, ValueSymbolTable *&ST) {
141 if (Instruction *I = dyn_cast<Instruction>(V)) {
142 if (BasicBlock *P = I->getParent())
143 if (Function *PP = P->getParent())
144 ST = &PP->getValueSymbolTable();
145 } else if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
146 if (Function *P = BB->getParent())
147 ST = &P->getValueSymbolTable();
148 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
149 if (Module *P = GV->getParent())
150 ST = &P->getValueSymbolTable();
151 } else if (Argument *A = dyn_cast<Argument>(V)) {
152 if (Function *P = A->getParent())
153 ST = &P->getValueSymbolTable();
155 assert(isa<Constant>(V) && "Unknown value type!");
156 return true; // no name is setable for this.
161 ValueName *Value::getValueName() const {
162 if (!HasName) return nullptr;
164 LLVMContext &Ctx = getContext();
165 auto I = Ctx.pImpl->ValueNames.find(this);
166 assert(I != Ctx.pImpl->ValueNames.end() &&
167 "No name entry found!");
172 void Value::setValueName(ValueName *VN) {
173 LLVMContext &Ctx = getContext();
175 assert(HasName == Ctx.pImpl->ValueNames.count(this) &&
176 "HasName bit out of sync!");
180 Ctx.pImpl->ValueNames.erase(this);
186 Ctx.pImpl->ValueNames[this] = VN;
189 StringRef Value::getName() const {
190 // Make sure the empty string is still a C string. For historical reasons,
191 // some clients want to call .data() on the result and expect it to be null
194 return StringRef("", 0);
195 return getValueName()->getKey();
198 void Value::setNameImpl(const Twine &NewName) {
199 // Fast path for common IRBuilder case of setName("") when there is no name.
200 if (NewName.isTriviallyEmpty() && !hasName())
203 SmallString<256> NameData;
204 StringRef NameRef = NewName.toStringRef(NameData);
205 assert(NameRef.find_first_of(0) == StringRef::npos &&
206 "Null bytes are not allowed in names");
208 // Name isn't changing?
209 if (getName() == NameRef)
212 assert(!getType()->isVoidTy() && "Cannot assign a name to void values!");
214 // Get the symbol table to update for this object.
215 ValueSymbolTable *ST;
216 if (getSymTab(this, ST))
217 return; // Cannot set a name on this value (e.g. constant).
219 if (!ST) { // No symbol table to update? Just do the change.
220 if (NameRef.empty()) {
221 // Free the name for this value.
226 // NOTE: Could optimize for the case the name is shrinking to not deallocate
230 // Create the new name.
231 setValueName(ValueName::Create(NameRef));
232 getValueName()->setValue(this);
236 // NOTE: Could optimize for the case the name is shrinking to not deallocate
240 ST->removeValueName(getValueName());
247 // Name is changing to something new.
248 setValueName(ST->createValueName(NameRef, this));
251 void Value::setName(const Twine &NewName) {
252 setNameImpl(NewName);
253 if (Function *F = dyn_cast<Function>(this))
254 F->recalculateIntrinsicID();
257 void Value::takeName(Value *V) {
258 ValueSymbolTable *ST = nullptr;
259 // If this value has a name, drop it.
261 // Get the symtab this is in.
262 if (getSymTab(this, ST)) {
263 // We can't set a name on this value, but we need to clear V's name if
265 if (V->hasName()) V->setName("");
266 return; // Cannot set a name on this value (e.g. constant).
271 ST->removeValueName(getValueName());
275 // Now we know that this has no name.
277 // If V has no name either, we're done.
278 if (!V->hasName()) return;
280 // Get this's symtab if we didn't before.
282 if (getSymTab(this, ST)) {
285 return; // Cannot set a name on this value (e.g. constant).
289 // Get V's ST, this should always succed, because V has a name.
290 ValueSymbolTable *VST;
291 bool Failure = getSymTab(V, VST);
292 assert(!Failure && "V has a name, so it should have a ST!"); (void)Failure;
294 // If these values are both in the same symtab, we can do this very fast.
295 // This works even if both values have no symtab yet.
298 setValueName(V->getValueName());
299 V->setValueName(nullptr);
300 getValueName()->setValue(this);
304 // Otherwise, things are slightly more complex. Remove V's name from VST and
305 // then reinsert it into ST.
308 VST->removeValueName(V->getValueName());
309 setValueName(V->getValueName());
310 V->setValueName(nullptr);
311 getValueName()->setValue(this);
314 ST->reinsertValue(this);
318 static bool contains(SmallPtrSetImpl<ConstantExpr *> &Cache, ConstantExpr *Expr,
320 if (!Cache.insert(Expr).second)
323 for (auto &O : Expr->operands()) {
326 auto *CE = dyn_cast<ConstantExpr>(O);
329 if (contains(Cache, CE, C))
335 static bool contains(Value *Expr, Value *V) {
339 auto *C = dyn_cast<Constant>(V);
343 auto *CE = dyn_cast<ConstantExpr>(Expr);
347 SmallPtrSet<ConstantExpr *, 4> Cache;
348 return contains(Cache, CE, C);
352 void Value::replaceAllUsesWith(Value *New) {
353 assert(New && "Value::replaceAllUsesWith(<null>) is invalid!");
354 assert(!contains(New, this) &&
355 "this->replaceAllUsesWith(expr(this)) is NOT valid!");
356 assert(New->getType() == getType() &&
357 "replaceAllUses of value with new value of different type!");
359 // Notify all ValueHandles (if present) that this value is going away.
361 ValueHandleBase::ValueIsRAUWd(this, New);
362 if (isUsedByMetadata())
363 ValueAsMetadata::handleRAUW(this, New);
365 while (!use_empty()) {
367 // Must handle Constants specially, we cannot call replaceUsesOfWith on a
368 // constant because they are uniqued.
369 if (auto *C = dyn_cast<Constant>(U.getUser())) {
370 if (!isa<GlobalValue>(C)) {
371 C->replaceUsesOfWithOnConstant(this, New, &U);
379 if (BasicBlock *BB = dyn_cast<BasicBlock>(this))
380 BB->replaceSuccessorsPhiUsesWith(cast<BasicBlock>(New));
383 // Like replaceAllUsesWith except it does not handle constants or basic blocks.
384 // This routine leaves uses within BB.
385 void Value::replaceUsesOutsideBlock(Value *New, BasicBlock *BB) {
386 assert(New && "Value::replaceUsesOutsideBlock(<null>, BB) is invalid!");
387 assert(!contains(New, this) &&
388 "this->replaceUsesOutsideBlock(expr(this), BB) is NOT valid!");
389 assert(New->getType() == getType() &&
390 "replaceUses of value with new value of different type!");
391 assert(BB && "Basic block that may contain a use of 'New' must be defined\n");
393 use_iterator UI = use_begin(), E = use_end();
397 auto *Usr = dyn_cast<Instruction>(U.getUser());
398 if (Usr && Usr->getParent() == BB)
406 // Various metrics for how much to strip off of pointers.
407 enum PointerStripKind {
409 PSK_ZeroIndicesAndAliases,
410 PSK_InBoundsConstantIndices,
414 template <PointerStripKind StripKind>
415 static Value *stripPointerCastsAndOffsets(Value *V) {
416 if (!V->getType()->isPointerTy())
419 // Even though we don't look through PHI nodes, we could be called on an
420 // instruction in an unreachable block, which may be on a cycle.
421 SmallPtrSet<Value *, 4> Visited;
425 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
427 case PSK_ZeroIndicesAndAliases:
428 case PSK_ZeroIndices:
429 if (!GEP->hasAllZeroIndices())
432 case PSK_InBoundsConstantIndices:
433 if (!GEP->hasAllConstantIndices())
437 if (!GEP->isInBounds())
441 V = GEP->getPointerOperand();
442 } else if (Operator::getOpcode(V) == Instruction::BitCast ||
443 Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
444 V = cast<Operator>(V)->getOperand(0);
445 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
446 if (StripKind == PSK_ZeroIndices || GA->mayBeOverridden())
448 V = GA->getAliasee();
452 assert(V->getType()->isPointerTy() && "Unexpected operand type!");
453 } while (Visited.insert(V).second);
459 Value *Value::stripPointerCasts() {
460 return stripPointerCastsAndOffsets<PSK_ZeroIndicesAndAliases>(this);
463 Value *Value::stripPointerCastsNoFollowAliases() {
464 return stripPointerCastsAndOffsets<PSK_ZeroIndices>(this);
467 Value *Value::stripInBoundsConstantOffsets() {
468 return stripPointerCastsAndOffsets<PSK_InBoundsConstantIndices>(this);
471 Value *Value::stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
473 if (!getType()->isPointerTy())
476 assert(Offset.getBitWidth() == DL.getPointerSizeInBits(cast<PointerType>(
477 getType())->getAddressSpace()) &&
478 "The offset must have exactly as many bits as our pointer.");
480 // Even though we don't look through PHI nodes, we could be called on an
481 // instruction in an unreachable block, which may be on a cycle.
482 SmallPtrSet<Value *, 4> Visited;
483 Visited.insert(this);
486 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
487 if (!GEP->isInBounds())
489 APInt GEPOffset(Offset);
490 if (!GEP->accumulateConstantOffset(DL, GEPOffset))
493 V = GEP->getPointerOperand();
494 } else if (Operator::getOpcode(V) == Instruction::BitCast ||
495 Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
496 V = cast<Operator>(V)->getOperand(0);
497 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
498 V = GA->getAliasee();
502 assert(V->getType()->isPointerTy() && "Unexpected operand type!");
503 } while (Visited.insert(V).second);
508 Value *Value::stripInBoundsOffsets() {
509 return stripPointerCastsAndOffsets<PSK_InBounds>(this);
512 Value *Value::DoPHITranslation(const BasicBlock *CurBB,
513 const BasicBlock *PredBB) {
514 PHINode *PN = dyn_cast<PHINode>(this);
515 if (PN && PN->getParent() == CurBB)
516 return PN->getIncomingValueForBlock(PredBB);
520 LLVMContext &Value::getContext() const { return VTy->getContext(); }
522 void Value::reverseUseList() {
523 if (!UseList || !UseList->Next)
524 // No need to reverse 0 or 1 uses.
528 Use *Current = UseList->Next;
529 Head->Next = nullptr;
531 Use *Next = Current->Next;
532 Current->Next = Head;
533 Head->setPrev(&Current->Next);
538 Head->setPrev(&UseList);
541 //===----------------------------------------------------------------------===//
542 // ValueHandleBase Class
543 //===----------------------------------------------------------------------===//
545 void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) {
546 assert(List && "Handle list is null?");
548 // Splice ourselves into the list.
553 Next->setPrevPtr(&Next);
554 assert(V == Next->V && "Added to wrong list?");
558 void ValueHandleBase::AddToExistingUseListAfter(ValueHandleBase *List) {
559 assert(List && "Must insert after existing node");
562 setPrevPtr(&List->Next);
565 Next->setPrevPtr(&Next);
568 void ValueHandleBase::AddToUseList() {
569 assert(V && "Null pointer doesn't have a use list!");
571 LLVMContextImpl *pImpl = V->getContext().pImpl;
573 if (V->HasValueHandle) {
574 // If this value already has a ValueHandle, then it must be in the
575 // ValueHandles map already.
576 ValueHandleBase *&Entry = pImpl->ValueHandles[V];
577 assert(Entry && "Value doesn't have any handles?");
578 AddToExistingUseList(&Entry);
582 // Ok, it doesn't have any handles yet, so we must insert it into the
583 // DenseMap. However, doing this insertion could cause the DenseMap to
584 // reallocate itself, which would invalidate all of the PrevP pointers that
585 // point into the old table. Handle this by checking for reallocation and
586 // updating the stale pointers only if needed.
587 DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
588 const void *OldBucketPtr = Handles.getPointerIntoBucketsArray();
590 ValueHandleBase *&Entry = Handles[V];
591 assert(!Entry && "Value really did already have handles?");
592 AddToExistingUseList(&Entry);
593 V->HasValueHandle = true;
595 // If reallocation didn't happen or if this was the first insertion, don't
597 if (Handles.isPointerIntoBucketsArray(OldBucketPtr) ||
598 Handles.size() == 1) {
602 // Okay, reallocation did happen. Fix the Prev Pointers.
603 for (DenseMap<Value*, ValueHandleBase*>::iterator I = Handles.begin(),
604 E = Handles.end(); I != E; ++I) {
605 assert(I->second && I->first == I->second->V &&
606 "List invariant broken!");
607 I->second->setPrevPtr(&I->second);
611 void ValueHandleBase::RemoveFromUseList() {
612 assert(V && V->HasValueHandle &&
613 "Pointer doesn't have a use list!");
615 // Unlink this from its use list.
616 ValueHandleBase **PrevPtr = getPrevPtr();
617 assert(*PrevPtr == this && "List invariant broken");
621 assert(Next->getPrevPtr() == &Next && "List invariant broken");
622 Next->setPrevPtr(PrevPtr);
626 // If the Next pointer was null, then it is possible that this was the last
627 // ValueHandle watching VP. If so, delete its entry from the ValueHandles
629 LLVMContextImpl *pImpl = V->getContext().pImpl;
630 DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
631 if (Handles.isPointerIntoBucketsArray(PrevPtr)) {
633 V->HasValueHandle = false;
638 void ValueHandleBase::ValueIsDeleted(Value *V) {
639 assert(V->HasValueHandle && "Should only be called if ValueHandles present");
641 // Get the linked list base, which is guaranteed to exist since the
642 // HasValueHandle flag is set.
643 LLVMContextImpl *pImpl = V->getContext().pImpl;
644 ValueHandleBase *Entry = pImpl->ValueHandles[V];
645 assert(Entry && "Value bit set but no entries exist");
647 // We use a local ValueHandleBase as an iterator so that ValueHandles can add
648 // and remove themselves from the list without breaking our iteration. This
649 // is not really an AssertingVH; we just have to give ValueHandleBase a kind.
650 // Note that we deliberately do not the support the case when dropping a value
651 // handle results in a new value handle being permanently added to the list
652 // (as might occur in theory for CallbackVH's): the new value handle will not
653 // be processed and the checking code will mete out righteous punishment if
654 // the handle is still present once we have finished processing all the other
655 // value handles (it is fine to momentarily add then remove a value handle).
656 for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) {
657 Iterator.RemoveFromUseList();
658 Iterator.AddToExistingUseListAfter(Entry);
659 assert(Entry->Next == &Iterator && "Loop invariant broken.");
661 switch (Entry->getKind()) {
665 // Mark that this value has been deleted by setting it to an invalid Value
667 Entry->operator=(DenseMapInfo<Value *>::getTombstoneKey());
670 // Weak just goes to null, which will unlink it from the list.
671 Entry->operator=(nullptr);
674 // Forward to the subclass's implementation.
675 static_cast<CallbackVH*>(Entry)->deleted();
680 // All callbacks, weak references, and assertingVHs should be dropped by now.
681 if (V->HasValueHandle) {
682 #ifndef NDEBUG // Only in +Asserts mode...
683 dbgs() << "While deleting: " << *V->getType() << " %" << V->getName()
685 if (pImpl->ValueHandles[V]->getKind() == Assert)
686 llvm_unreachable("An asserting value handle still pointed to this"
690 llvm_unreachable("All references to V were not removed?");
695 void ValueHandleBase::ValueIsRAUWd(Value *Old, Value *New) {
696 assert(Old->HasValueHandle &&"Should only be called if ValueHandles present");
697 assert(Old != New && "Changing value into itself!");
698 assert(Old->getType() == New->getType() &&
699 "replaceAllUses of value with new value of different type!");
701 // Get the linked list base, which is guaranteed to exist since the
702 // HasValueHandle flag is set.
703 LLVMContextImpl *pImpl = Old->getContext().pImpl;
704 ValueHandleBase *Entry = pImpl->ValueHandles[Old];
706 assert(Entry && "Value bit set but no entries exist");
708 // We use a local ValueHandleBase as an iterator so that
709 // ValueHandles can add and remove themselves from the list without
710 // breaking our iteration. This is not really an AssertingVH; we
711 // just have to give ValueHandleBase some kind.
712 for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) {
713 Iterator.RemoveFromUseList();
714 Iterator.AddToExistingUseListAfter(Entry);
715 assert(Entry->Next == &Iterator && "Loop invariant broken.");
717 switch (Entry->getKind()) {
719 // Asserting handle does not follow RAUW implicitly.
722 // Tracking goes to new value like a WeakVH. Note that this may make it
723 // something incompatible with its templated type. We don't want to have a
724 // virtual (or inline) interface to handle this though, so instead we make
725 // the TrackingVH accessors guarantee that a client never sees this value.
729 // Weak goes to the new value, which will unlink it from Old's list.
730 Entry->operator=(New);
733 // Forward to the subclass's implementation.
734 static_cast<CallbackVH*>(Entry)->allUsesReplacedWith(New);
740 // If any new tracking or weak value handles were added while processing the
741 // list, then complain about it now.
742 if (Old->HasValueHandle)
743 for (Entry = pImpl->ValueHandles[Old]; Entry; Entry = Entry->Next)
744 switch (Entry->getKind()) {
747 dbgs() << "After RAUW from " << *Old->getType() << " %"
748 << Old->getName() << " to " << *New->getType() << " %"
749 << New->getName() << "\n";
750 llvm_unreachable("A tracking or weak value handle still pointed to the"
758 // Pin the vtable to this file.
759 void CallbackVH::anchor() {}