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), HasValueHandle(0),
50 SubclassOptionalData(0), SubclassData(0), NumOperands(0) {
51 // FIXME: Why isn't this in the subclass gunk??
52 // Note, we cannot call isa<CallInst> before the CallInst has been
54 if (SubclassID == Instruction::Call || SubclassID == Instruction::Invoke)
55 assert((VTy->isFirstClassType() || VTy->isVoidTy() || VTy->isStructTy()) &&
56 "invalid CallInst type!");
57 else if (SubclassID != BasicBlockVal &&
58 (SubclassID < ConstantFirstVal || SubclassID > ConstantLastVal))
59 assert((VTy->isFirstClassType() || VTy->isVoidTy()) &&
60 "Cannot create non-first-class values except for constants!");
64 // Notify all ValueHandles (if present) that this value is going away.
66 ValueHandleBase::ValueIsDeleted(this);
67 if (isUsedByMetadata())
68 ValueAsMetadata::handleDeletion(this);
70 #ifndef NDEBUG // Only in -g mode...
71 // Check to make sure that there are no uses of this value that are still
72 // around when the value is destroyed. If there are, then we have a dangling
73 // reference and something is wrong. This code is here to print out where
74 // the value is still being referenced.
77 dbgs() << "While deleting: " << *VTy << " %" << getName() << "\n";
78 for (auto *U : users())
79 dbgs() << "Use still stuck around after Def is destroyed:" << *U << "\n";
82 assert(use_empty() && "Uses remain when a value is destroyed!");
84 // If this value is named, destroy the name. This should not be in a symtab
89 void Value::destroyValueName() {
90 ValueName *Name = getValueName();
93 setValueName(nullptr);
96 bool Value::hasNUses(unsigned N) const {
97 const_use_iterator UI = use_begin(), E = use_end();
100 if (UI == E) return false; // Too few.
104 bool Value::hasNUsesOrMore(unsigned N) const {
105 const_use_iterator UI = use_begin(), E = use_end();
108 if (UI == E) return false; // Too few.
113 bool Value::isUsedInBasicBlock(const BasicBlock *BB) const {
114 // This can be computed either by scanning the instructions in BB, or by
115 // scanning the use list of this Value. Both lists can be very long, but
116 // usually one is quite short.
118 // Scan both lists simultaneously until one is exhausted. This limits the
119 // search to the shorter list.
120 BasicBlock::const_iterator BI = BB->begin(), BE = BB->end();
121 const_user_iterator UI = user_begin(), UE = user_end();
122 for (; BI != BE && UI != UE; ++BI, ++UI) {
123 // Scan basic block: Check if this Value is used by the instruction at BI.
124 if (std::find(BI->op_begin(), BI->op_end(), this) != BI->op_end())
126 // Scan use list: Check if the use at UI is in BB.
127 const Instruction *User = dyn_cast<Instruction>(*UI);
128 if (User && User->getParent() == BB)
134 unsigned Value::getNumUses() const {
135 return (unsigned)std::distance(use_begin(), use_end());
138 static bool getSymTab(Value *V, ValueSymbolTable *&ST) {
140 if (Instruction *I = dyn_cast<Instruction>(V)) {
141 if (BasicBlock *P = I->getParent())
142 if (Function *PP = P->getParent())
143 ST = &PP->getValueSymbolTable();
144 } else if (BasicBlock *BB = dyn_cast<BasicBlock>(V)) {
145 if (Function *P = BB->getParent())
146 ST = &P->getValueSymbolTable();
147 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
148 if (Module *P = GV->getParent())
149 ST = &P->getValueSymbolTable();
150 } else if (Argument *A = dyn_cast<Argument>(V)) {
151 if (Function *P = A->getParent())
152 ST = &P->getValueSymbolTable();
154 assert(isa<Constant>(V) && "Unknown value type!");
155 return true; // no name is setable for this.
160 StringRef Value::getName() const {
161 // Make sure the empty string is still a C string. For historical reasons,
162 // some clients want to call .data() on the result and expect it to be null
165 return StringRef("", 0);
166 return getValueName()->getKey();
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 StringRef NameRef = NewName.toStringRef(NameData);
176 assert(NameRef.find_first_of(0) == StringRef::npos &&
177 "Null bytes are not allowed in names");
179 // Name isn't changing?
180 if (getName() == NameRef)
183 assert(!getType()->isVoidTy() && "Cannot assign a name to void values!");
185 // Get the symbol table to update for this object.
186 ValueSymbolTable *ST;
187 if (getSymTab(this, ST))
188 return; // Cannot set a name on this value (e.g. constant).
190 if (Function *F = dyn_cast<Function>(this))
191 getContext().pImpl->IntrinsicIDCache.erase(F);
193 if (!ST) { // No symbol table to update? Just do the change.
194 if (NameRef.empty()) {
195 // Free the name for this value.
200 // NOTE: Could optimize for the case the name is shrinking to not deallocate
204 // Create the new name.
205 setValueName(ValueName::Create(NameRef));
206 getValueName()->setValue(this);
210 // NOTE: Could optimize for the case the name is shrinking to not deallocate
214 ST->removeValueName(getValueName());
221 // Name is changing to something new.
222 setValueName(ST->createValueName(NameRef, this));
225 void Value::takeName(Value *V) {
226 ValueSymbolTable *ST = nullptr;
227 // If this value has a name, drop it.
229 // Get the symtab this is in.
230 if (getSymTab(this, ST)) {
231 // We can't set a name on this value, but we need to clear V's name if
233 if (V->hasName()) V->setName("");
234 return; // Cannot set a name on this value (e.g. constant).
239 ST->removeValueName(getValueName());
243 // Now we know that this has no name.
245 // If V has no name either, we're done.
246 if (!V->hasName()) return;
248 // Get this's symtab if we didn't before.
250 if (getSymTab(this, ST)) {
253 return; // Cannot set a name on this value (e.g. constant).
257 // Get V's ST, this should always succed, because V has a name.
258 ValueSymbolTable *VST;
259 bool Failure = getSymTab(V, VST);
260 assert(!Failure && "V has a name, so it should have a ST!"); (void)Failure;
262 // If these values are both in the same symtab, we can do this very fast.
263 // This works even if both values have no symtab yet.
266 setValueName(V->getValueName());
267 V->setValueName(nullptr);
268 getValueName()->setValue(this);
272 // Otherwise, things are slightly more complex. Remove V's name from VST and
273 // then reinsert it into ST.
276 VST->removeValueName(V->getValueName());
277 setValueName(V->getValueName());
278 V->setValueName(nullptr);
279 getValueName()->setValue(this);
282 ST->reinsertValue(this);
286 static bool contains(SmallPtrSetImpl<ConstantExpr *> &Cache, ConstantExpr *Expr,
288 if (!Cache.insert(Expr).second)
291 for (auto &O : Expr->operands()) {
294 auto *CE = dyn_cast<ConstantExpr>(O);
297 if (contains(Cache, CE, C))
303 static bool contains(Value *Expr, Value *V) {
307 auto *C = dyn_cast<Constant>(V);
311 auto *CE = dyn_cast<ConstantExpr>(Expr);
315 SmallPtrSet<ConstantExpr *, 4> Cache;
316 return contains(Cache, CE, C);
320 void Value::replaceAllUsesWith(Value *New) {
321 assert(New && "Value::replaceAllUsesWith(<null>) is invalid!");
322 assert(!contains(New, this) &&
323 "this->replaceAllUsesWith(expr(this)) is NOT valid!");
324 assert(New->getType() == getType() &&
325 "replaceAllUses of value with new value of different type!");
327 // Notify all ValueHandles (if present) that this value is going away.
329 ValueHandleBase::ValueIsRAUWd(this, New);
330 if (isUsedByMetadata())
331 ValueAsMetadata::handleRAUW(this, New);
333 while (!use_empty()) {
335 // Must handle Constants specially, we cannot call replaceUsesOfWith on a
336 // constant because they are uniqued.
337 if (auto *C = dyn_cast<Constant>(U.getUser())) {
338 if (!isa<GlobalValue>(C)) {
339 C->replaceUsesOfWithOnConstant(this, New, &U);
347 if (BasicBlock *BB = dyn_cast<BasicBlock>(this))
348 BB->replaceSuccessorsPhiUsesWith(cast<BasicBlock>(New));
351 // Like replaceAllUsesWith except it does not handle constants or basic blocks.
352 // This routine leaves uses within BB.
353 void Value::replaceUsesOutsideBlock(Value *New, BasicBlock *BB) {
354 assert(New && "Value::replaceUsesOutsideBlock(<null>, BB) is invalid!");
355 assert(!contains(New, this) &&
356 "this->replaceUsesOutsideBlock(expr(this), BB) is NOT valid!");
357 assert(New->getType() == getType() &&
358 "replaceUses of value with new value of different type!");
359 assert(BB && "Basic block that may contain a use of 'New' must be defined\n");
361 use_iterator UI = use_begin(), E = use_end();
365 auto *Usr = dyn_cast<Instruction>(U.getUser());
366 if (Usr && Usr->getParent() == BB)
374 // Various metrics for how much to strip off of pointers.
375 enum PointerStripKind {
377 PSK_ZeroIndicesAndAliases,
378 PSK_InBoundsConstantIndices,
382 template <PointerStripKind StripKind>
383 static Value *stripPointerCastsAndOffsets(Value *V) {
384 if (!V->getType()->isPointerTy())
387 // Even though we don't look through PHI nodes, we could be called on an
388 // instruction in an unreachable block, which may be on a cycle.
389 SmallPtrSet<Value *, 4> Visited;
393 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
395 case PSK_ZeroIndicesAndAliases:
396 case PSK_ZeroIndices:
397 if (!GEP->hasAllZeroIndices())
400 case PSK_InBoundsConstantIndices:
401 if (!GEP->hasAllConstantIndices())
405 if (!GEP->isInBounds())
409 V = GEP->getPointerOperand();
410 } else if (Operator::getOpcode(V) == Instruction::BitCast ||
411 Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
412 V = cast<Operator>(V)->getOperand(0);
413 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
414 if (StripKind == PSK_ZeroIndices || GA->mayBeOverridden())
416 V = GA->getAliasee();
420 assert(V->getType()->isPointerTy() && "Unexpected operand type!");
421 } while (Visited.insert(V).second);
427 Value *Value::stripPointerCasts() {
428 return stripPointerCastsAndOffsets<PSK_ZeroIndicesAndAliases>(this);
431 Value *Value::stripPointerCastsNoFollowAliases() {
432 return stripPointerCastsAndOffsets<PSK_ZeroIndices>(this);
435 Value *Value::stripInBoundsConstantOffsets() {
436 return stripPointerCastsAndOffsets<PSK_InBoundsConstantIndices>(this);
439 Value *Value::stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
441 if (!getType()->isPointerTy())
444 assert(Offset.getBitWidth() == DL.getPointerSizeInBits(cast<PointerType>(
445 getType())->getAddressSpace()) &&
446 "The offset must have exactly as many bits as our pointer.");
448 // Even though we don't look through PHI nodes, we could be called on an
449 // instruction in an unreachable block, which may be on a cycle.
450 SmallPtrSet<Value *, 4> Visited;
451 Visited.insert(this);
454 if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
455 if (!GEP->isInBounds())
457 APInt GEPOffset(Offset);
458 if (!GEP->accumulateConstantOffset(DL, GEPOffset))
461 V = GEP->getPointerOperand();
462 } else if (Operator::getOpcode(V) == Instruction::BitCast ||
463 Operator::getOpcode(V) == Instruction::AddrSpaceCast) {
464 V = cast<Operator>(V)->getOperand(0);
465 } else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
466 V = GA->getAliasee();
470 assert(V->getType()->isPointerTy() && "Unexpected operand type!");
471 } while (Visited.insert(V).second);
476 Value *Value::stripInBoundsOffsets() {
477 return stripPointerCastsAndOffsets<PSK_InBounds>(this);
480 Value *Value::DoPHITranslation(const BasicBlock *CurBB,
481 const BasicBlock *PredBB) {
482 PHINode *PN = dyn_cast<PHINode>(this);
483 if (PN && PN->getParent() == CurBB)
484 return PN->getIncomingValueForBlock(PredBB);
488 LLVMContext &Value::getContext() const { return VTy->getContext(); }
490 void Value::reverseUseList() {
491 if (!UseList || !UseList->Next)
492 // No need to reverse 0 or 1 uses.
496 Use *Current = UseList->Next;
497 Head->Next = nullptr;
499 Use *Next = Current->Next;
500 Current->Next = Head;
501 Head->setPrev(&Current->Next);
506 Head->setPrev(&UseList);
509 //===----------------------------------------------------------------------===//
510 // ValueHandleBase Class
511 //===----------------------------------------------------------------------===//
513 void ValueHandleBase::AddToExistingUseList(ValueHandleBase **List) {
514 assert(List && "Handle list is null?");
516 // Splice ourselves into the list.
521 Next->setPrevPtr(&Next);
522 assert(V == Next->V && "Added to wrong list?");
526 void ValueHandleBase::AddToExistingUseListAfter(ValueHandleBase *List) {
527 assert(List && "Must insert after existing node");
530 setPrevPtr(&List->Next);
533 Next->setPrevPtr(&Next);
536 void ValueHandleBase::AddToUseList() {
537 assert(V && "Null pointer doesn't have a use list!");
539 LLVMContextImpl *pImpl = V->getContext().pImpl;
541 if (V->HasValueHandle) {
542 // If this value already has a ValueHandle, then it must be in the
543 // ValueHandles map already.
544 ValueHandleBase *&Entry = pImpl->ValueHandles[V];
545 assert(Entry && "Value doesn't have any handles?");
546 AddToExistingUseList(&Entry);
550 // Ok, it doesn't have any handles yet, so we must insert it into the
551 // DenseMap. However, doing this insertion could cause the DenseMap to
552 // reallocate itself, which would invalidate all of the PrevP pointers that
553 // point into the old table. Handle this by checking for reallocation and
554 // updating the stale pointers only if needed.
555 DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
556 const void *OldBucketPtr = Handles.getPointerIntoBucketsArray();
558 ValueHandleBase *&Entry = Handles[V];
559 assert(!Entry && "Value really did already have handles?");
560 AddToExistingUseList(&Entry);
561 V->HasValueHandle = true;
563 // If reallocation didn't happen or if this was the first insertion, don't
565 if (Handles.isPointerIntoBucketsArray(OldBucketPtr) ||
566 Handles.size() == 1) {
570 // Okay, reallocation did happen. Fix the Prev Pointers.
571 for (DenseMap<Value*, ValueHandleBase*>::iterator I = Handles.begin(),
572 E = Handles.end(); I != E; ++I) {
573 assert(I->second && I->first == I->second->V &&
574 "List invariant broken!");
575 I->second->setPrevPtr(&I->second);
579 void ValueHandleBase::RemoveFromUseList() {
580 assert(V && V->HasValueHandle &&
581 "Pointer doesn't have a use list!");
583 // Unlink this from its use list.
584 ValueHandleBase **PrevPtr = getPrevPtr();
585 assert(*PrevPtr == this && "List invariant broken");
589 assert(Next->getPrevPtr() == &Next && "List invariant broken");
590 Next->setPrevPtr(PrevPtr);
594 // If the Next pointer was null, then it is possible that this was the last
595 // ValueHandle watching VP. If so, delete its entry from the ValueHandles
597 LLVMContextImpl *pImpl = V->getContext().pImpl;
598 DenseMap<Value*, ValueHandleBase*> &Handles = pImpl->ValueHandles;
599 if (Handles.isPointerIntoBucketsArray(PrevPtr)) {
601 V->HasValueHandle = false;
606 void ValueHandleBase::ValueIsDeleted(Value *V) {
607 assert(V->HasValueHandle && "Should only be called if ValueHandles present");
609 // Get the linked list base, which is guaranteed to exist since the
610 // HasValueHandle flag is set.
611 LLVMContextImpl *pImpl = V->getContext().pImpl;
612 ValueHandleBase *Entry = pImpl->ValueHandles[V];
613 assert(Entry && "Value bit set but no entries exist");
615 // We use a local ValueHandleBase as an iterator so that ValueHandles can add
616 // and remove themselves from the list without breaking our iteration. This
617 // is not really an AssertingVH; we just have to give ValueHandleBase a kind.
618 // Note that we deliberately do not the support the case when dropping a value
619 // handle results in a new value handle being permanently added to the list
620 // (as might occur in theory for CallbackVH's): the new value handle will not
621 // be processed and the checking code will mete out righteous punishment if
622 // the handle is still present once we have finished processing all the other
623 // value handles (it is fine to momentarily add then remove a value handle).
624 for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) {
625 Iterator.RemoveFromUseList();
626 Iterator.AddToExistingUseListAfter(Entry);
627 assert(Entry->Next == &Iterator && "Loop invariant broken.");
629 switch (Entry->getKind()) {
633 // Mark that this value has been deleted by setting it to an invalid Value
635 Entry->operator=(DenseMapInfo<Value *>::getTombstoneKey());
638 // Weak just goes to null, which will unlink it from the list.
639 Entry->operator=(nullptr);
642 // Forward to the subclass's implementation.
643 static_cast<CallbackVH*>(Entry)->deleted();
648 // All callbacks, weak references, and assertingVHs should be dropped by now.
649 if (V->HasValueHandle) {
650 #ifndef NDEBUG // Only in +Asserts mode...
651 dbgs() << "While deleting: " << *V->getType() << " %" << V->getName()
653 if (pImpl->ValueHandles[V]->getKind() == Assert)
654 llvm_unreachable("An asserting value handle still pointed to this"
658 llvm_unreachable("All references to V were not removed?");
663 void ValueHandleBase::ValueIsRAUWd(Value *Old, Value *New) {
664 assert(Old->HasValueHandle &&"Should only be called if ValueHandles present");
665 assert(Old != New && "Changing value into itself!");
666 assert(Old->getType() == New->getType() &&
667 "replaceAllUses of value with new value of different type!");
669 // Get the linked list base, which is guaranteed to exist since the
670 // HasValueHandle flag is set.
671 LLVMContextImpl *pImpl = Old->getContext().pImpl;
672 ValueHandleBase *Entry = pImpl->ValueHandles[Old];
674 assert(Entry && "Value bit set but no entries exist");
676 // We use a local ValueHandleBase as an iterator so that
677 // ValueHandles can add and remove themselves from the list without
678 // breaking our iteration. This is not really an AssertingVH; we
679 // just have to give ValueHandleBase some kind.
680 for (ValueHandleBase Iterator(Assert, *Entry); Entry; Entry = Iterator.Next) {
681 Iterator.RemoveFromUseList();
682 Iterator.AddToExistingUseListAfter(Entry);
683 assert(Entry->Next == &Iterator && "Loop invariant broken.");
685 switch (Entry->getKind()) {
687 // Asserting handle does not follow RAUW implicitly.
690 // Tracking goes to new value like a WeakVH. Note that this may make it
691 // something incompatible with its templated type. We don't want to have a
692 // virtual (or inline) interface to handle this though, so instead we make
693 // the TrackingVH accessors guarantee that a client never sees this value.
697 // Weak goes to the new value, which will unlink it from Old's list.
698 Entry->operator=(New);
701 // Forward to the subclass's implementation.
702 static_cast<CallbackVH*>(Entry)->allUsesReplacedWith(New);
708 // If any new tracking or weak value handles were added while processing the
709 // list, then complain about it now.
710 if (Old->HasValueHandle)
711 for (Entry = pImpl->ValueHandles[Old]; Entry; Entry = Entry->Next)
712 switch (Entry->getKind()) {
715 dbgs() << "After RAUW from " << *Old->getType() << " %"
716 << Old->getName() << " to " << *New->getType() << " %"
717 << New->getName() << "\n";
718 llvm_unreachable("A tracking or weak value handle still pointed to the"
726 // Pin the vtable to this file.
727 void CallbackVH::anchor() {}