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() || VTy
->isVoidTy() ||
48 ty
->isOpaqueTy() || VTy
->isStructTy()) &&
49 "invalid CallInst type!");
50 else if (!isa
<Constant
>(this) && !isa
<BasicBlock
>(this))
51 assert((VTy
->isFirstClassType() || VTy
->isVoidTy() ||
53 "Cannot create non-first-class values except for constants!");
57 // Notify all ValueHandles (if present) that this value is going away.
59 ValueHandleBase::ValueIsDeleted(this);
61 #ifndef NDEBUG // Only in -g mode...
62 // Check to make sure that there are no uses of this value that are still
63 // around when the value is destroyed. If there are, then we have a dangling
64 // reference and something is wrong. This code is here to print out what is
65 // still being referenced. The value in question should be printed as
69 dbgs() << "While deleting: " << *VTy
<< " %" << getNameStr() << "\n";
70 for (use_iterator I
= use_begin(), E
= use_end(); I
!= E
; ++I
)
71 dbgs() << "Use still stuck around after Def is destroyed:"
75 assert(use_empty() && "Uses remain when a value is destroyed!");
77 // If this value is named, destroy the name. This should not be in a symtab
82 // There should be no uses of this object anymore, remove it.
83 LeakDetector::removeGarbageObject(this);
86 /// hasNUses - Return true if this Value has exactly N users.
88 bool Value::hasNUses(unsigned N
) const {
89 const_use_iterator UI
= use_begin(), E
= use_end();
92 if (UI
== E
) return false; // Too few.
96 /// hasNUsesOrMore - Return true if this value has N users or more. This is
97 /// logically equivalent to getNumUses() >= N.
99 bool Value::hasNUsesOrMore(unsigned N
) const {
100 const_use_iterator UI
= use_begin(), E
= use_end();
103 if (UI
== E
) return false; // Too few.
108 /// isUsedInBasicBlock - Return true if this value is used in the specified
110 bool Value::isUsedInBasicBlock(const BasicBlock
*BB
) const {
111 for (const_use_iterator I
= use_begin(), E
= use_end(); I
!= E
; ++I
) {
112 const Instruction
*User
= dyn_cast
<Instruction
>(*I
);
113 if (User
&& User
->getParent() == BB
)
120 /// getNumUses - This method computes the number of uses of this Value. This
121 /// is a linear time operation. Use hasOneUse or hasNUses to check for specific
123 unsigned Value::getNumUses() const {
124 return (unsigned)std::distance(use_begin(), use_end());
127 static bool getSymTab(Value
*V
, ValueSymbolTable
*&ST
) {
129 if (Instruction
*I
= dyn_cast
<Instruction
>(V
)) {
130 if (BasicBlock
*P
= I
->getParent())
131 if (Function
*PP
= P
->getParent())
132 ST
= &PP
->getValueSymbolTable();
133 } else if (BasicBlock
*BB
= dyn_cast
<BasicBlock
>(V
)) {
134 if (Function
*P
= BB
->getParent())
135 ST
= &P
->getValueSymbolTable();
136 } else if (GlobalValue
*GV
= dyn_cast
<GlobalValue
>(V
)) {
137 if (Module
*P
= GV
->getParent())
138 ST
= &P
->getValueSymbolTable();
139 } else if (Argument
*A
= dyn_cast
<Argument
>(V
)) {
140 if (Function
*P
= A
->getParent())
141 ST
= &P
->getValueSymbolTable();
142 } else if (NamedMDNode
*N
= dyn_cast
<NamedMDNode
>(V
)) {
143 if (Module
*P
= N
->getParent()) {
144 ST
= &P
->getValueSymbolTable();
146 } else if (isa
<MDString
>(V
))
149 assert(isa
<Constant
>(V
) && "Unknown value type!");
150 return true; // no name is setable for this.
155 StringRef
Value::getName() const {
156 // Make sure the empty string is still a C string. For historical reasons,
157 // some clients want to call .data() on the result and expect it to be null
159 if (!Name
) return StringRef("", 0);
160 return Name
->getKey();
163 std::string
Value::getNameStr() const {
164 return getName().str();
167 void Value::setName(const Twine
&NewName
) {
168 // Fast path for common IRBuilder case of setName("") when there is no name.
169 if (NewName
.isTriviallyEmpty() && !hasName())
172 SmallString
<256> NameData
;
173 StringRef NameRef
= NewName
.toStringRef(NameData
);
175 // Name isn't changing?
176 if (getName() == NameRef
)
179 assert(!getType()->isVoidTy() && "Cannot assign a name to void values!");
181 // Get the symbol table to update for this object.
182 ValueSymbolTable
*ST
;
183 if (getSymTab(this, ST
))
184 return; // Cannot set a name on this value (e.g. constant).
186 if (!ST
) { // No symbol table to update? Just do the change.
187 if (NameRef
.empty()) {
188 // Free the name for this value.
197 // NOTE: Could optimize for the case the name is shrinking to not deallocate
200 // Create the new name.
201 Name
= ValueName::Create(NameRef
.begin(), NameRef
.end());
202 Name
->setValue(this);
206 // NOTE: Could optimize for the case the name is shrinking to not deallocate
210 ST
->removeValueName(Name
);
218 // Name is changing to something new.
219 Name
= ST
->createValueName(NameRef
, this);
223 /// takeName - transfer the name from V to this value, setting V's name to
224 /// empty. It is an error to call V->takeName(V).
225 void Value::takeName(Value
*V
) {
226 ValueSymbolTable
*ST
= 0;
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(Name
);
244 // Now we know that this has no name.
246 // If V has no name either, we're done.
247 if (!V
->hasName()) return;
249 // Get this's symtab if we didn't before.
251 if (getSymTab(this, ST
)) {
254 return; // Cannot set a name on this value (e.g. constant).
258 // Get V's ST, this should always succed, because V has a name.
259 ValueSymbolTable
*VST
;
260 bool Failure
= getSymTab(V
, VST
);
261 assert(!Failure
&& "V has a name, so it should have a ST!"); Failure
=Failure
;
263 // If these values are both in the same symtab, we can do this very fast.
264 // This works even if both values have no symtab yet.
269 Name
->setValue(this);
273 // Otherwise, things are slightly more complex. Remove V's name from VST and
274 // then reinsert it into ST.
277 VST
->removeValueName(V
->Name
);
280 Name
->setValue(this);
283 ST
->reinsertValue(this);
287 // uncheckedReplaceAllUsesWith - This is exactly the same as replaceAllUsesWith,
288 // except that it doesn't have all of the asserts. The asserts fail because we
289 // are half-way done resolving types, which causes some types to exist as two
290 // different Type*'s at the same time. This is a sledgehammer to work around
293 void Value::uncheckedReplaceAllUsesWith(Value
*New
) {
294 // Notify all ValueHandles (if present) that this value is going away.
296 ValueHandleBase::ValueIsRAUWd(this, New
);
298 while (!use_empty()) {
300 // Must handle Constants specially, we cannot call replaceUsesOfWith on a
301 // constant because they are uniqued.
302 if (Constant
*C
= dyn_cast
<Constant
>(U
.getUser())) {
303 if (!isa
<GlobalValue
>(C
)) {
304 C
->replaceUsesOfWithOnConstant(this, New
, &U
);
313 void Value::replaceAllUsesWith(Value
*New
) {
314 assert(New
&& "Value::replaceAllUsesWith(<null>) is invalid!");
315 assert(New
!= this && "this->replaceAllUsesWith(this) is NOT valid!");
316 assert(New
->getType() == getType() &&
317 "replaceAllUses of value with new value of different type!");
319 uncheckedReplaceAllUsesWith(New
);
322 Value
*Value::stripPointerCasts() {
323 if (!getType()->isPointerTy())
327 if (GEPOperator
*GEP
= dyn_cast
<GEPOperator
>(V
)) {
328 if (!GEP
->hasAllZeroIndices())
330 V
= GEP
->getPointerOperand();
331 } else if (Operator::getOpcode(V
) == Instruction::BitCast
) {
332 V
= cast
<Operator
>(V
)->getOperand(0);
333 } else if (GlobalAlias
*GA
= dyn_cast
<GlobalAlias
>(V
)) {
334 if (GA
->mayBeOverridden())
336 V
= GA
->getAliasee();
340 assert(V
->getType()->isPointerTy() && "Unexpected operand type!");
344 Value
*Value::getUnderlyingObject(unsigned MaxLookup
) {
345 if (!getType()->isPointerTy())
348 for (unsigned Count
= 0; MaxLookup
== 0 || Count
< MaxLookup
; ++Count
) {
349 if (GEPOperator
*GEP
= dyn_cast
<GEPOperator
>(V
)) {
350 V
= GEP
->getPointerOperand();
351 } else if (Operator::getOpcode(V
) == Instruction::BitCast
) {
352 V
= cast
<Operator
>(V
)->getOperand(0);
353 } else if (GlobalAlias
*GA
= dyn_cast
<GlobalAlias
>(V
)) {
354 if (GA
->mayBeOverridden())
356 V
= GA
->getAliasee();
360 assert(V
->getType()->isPointerTy() && "Unexpected operand type!");
365 /// DoPHITranslation - If this value is a PHI node with CurBB as its parent,
366 /// return the value in the PHI node corresponding to PredBB. If not, return
367 /// ourself. This is useful if you want to know the value something has in a
368 /// predecessor block.
369 Value
*Value::DoPHITranslation(const BasicBlock
*CurBB
,
370 const BasicBlock
*PredBB
) {
371 PHINode
*PN
= dyn_cast
<PHINode
>(this);
372 if (PN
&& PN
->getParent() == CurBB
)
373 return PN
->getIncomingValueForBlock(PredBB
);
377 LLVMContext
&Value::getContext() const { return VTy
->getContext(); }
379 //===----------------------------------------------------------------------===//
380 // ValueHandleBase Class
381 //===----------------------------------------------------------------------===//
383 /// AddToExistingUseList - Add this ValueHandle to the use list for VP, where
384 /// List is known to point into the existing use list.
385 void ValueHandleBase::AddToExistingUseList(ValueHandleBase
**List
) {
386 assert(List
&& "Handle list is null?");
388 // Splice ourselves into the list.
393 Next
->setPrevPtr(&Next
);
394 assert(VP
== Next
->VP
&& "Added to wrong list?");
398 void ValueHandleBase::AddToExistingUseListAfter(ValueHandleBase
*List
) {
399 assert(List
&& "Must insert after existing node");
402 setPrevPtr(&List
->Next
);
405 Next
->setPrevPtr(&Next
);
408 /// AddToUseList - Add this ValueHandle to the use list for VP.
409 void ValueHandleBase::AddToUseList() {
410 assert(VP
&& "Null pointer doesn't have a use list!");
412 LLVMContextImpl
*pImpl
= VP
->getContext().pImpl
;
414 if (VP
->HasValueHandle
) {
415 // If this value already has a ValueHandle, then it must be in the
416 // ValueHandles map already.
417 ValueHandleBase
*&Entry
= pImpl
->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 DenseMap
<Value
*, ValueHandleBase
*> &Handles
= pImpl
->ValueHandles
;
429 const void *OldBucketPtr
= Handles
.getPointerIntoBucketsArray();
431 ValueHandleBase
*&Entry
= Handles
[VP
];
432 assert(Entry
== 0 && "Value really did already have handles?");
433 AddToExistingUseList(&Entry
);
434 VP
->HasValueHandle
= true;
436 // If reallocation didn't happen or if this was the first insertion, don't
438 if (Handles
.isPointerIntoBucketsArray(OldBucketPtr
) ||
439 Handles
.size() == 1) {
443 // Okay, reallocation did happen. Fix the Prev Pointers.
444 for (DenseMap
<Value
*, ValueHandleBase
*>::iterator I
= Handles
.begin(),
445 E
= Handles
.end(); I
!= E
; ++I
) {
446 assert(I
->second
&& I
->first
== I
->second
->VP
&& "List invariant broken!");
447 I
->second
->setPrevPtr(&I
->second
);
451 /// RemoveFromUseList - Remove this ValueHandle from its current use list.
452 void ValueHandleBase::RemoveFromUseList() {
453 assert(VP
&& VP
->HasValueHandle
&& "Pointer doesn't have a use list!");
455 // Unlink this from its use list.
456 ValueHandleBase
**PrevPtr
= getPrevPtr();
457 assert(*PrevPtr
== this && "List invariant broken");
461 assert(Next
->getPrevPtr() == &Next
&& "List invariant broken");
462 Next
->setPrevPtr(PrevPtr
);
466 // If the Next pointer was null, then it is possible that this was the last
467 // ValueHandle watching VP. If so, delete its entry from the ValueHandles
469 LLVMContextImpl
*pImpl
= VP
->getContext().pImpl
;
470 DenseMap
<Value
*, ValueHandleBase
*> &Handles
= pImpl
->ValueHandles
;
471 if (Handles
.isPointerIntoBucketsArray(PrevPtr
)) {
473 VP
->HasValueHandle
= false;
478 void ValueHandleBase::ValueIsDeleted(Value
*V
) {
479 assert(V
->HasValueHandle
&& "Should only be called if ValueHandles present");
481 // Get the linked list base, which is guaranteed to exist since the
482 // HasValueHandle flag is set.
483 LLVMContextImpl
*pImpl
= V
->getContext().pImpl
;
484 ValueHandleBase
*Entry
= pImpl
->ValueHandles
[V
];
485 assert(Entry
&& "Value bit set but no entries exist");
487 // We use a local ValueHandleBase as an iterator so that
488 // ValueHandles can add and remove themselves from the list without
489 // breaking our iteration. This is not really an AssertingVH; we
490 // just have to give ValueHandleBase some kind.
491 for (ValueHandleBase
Iterator(Assert
, *Entry
); Entry
; Entry
= Iterator
.Next
) {
492 Iterator
.RemoveFromUseList();
493 Iterator
.AddToExistingUseListAfter(Entry
);
494 assert(Entry
->Next
== &Iterator
&& "Loop invariant broken.");
496 switch (Entry
->getKind()) {
500 // Mark that this value has been deleted by setting it to an invalid Value
502 Entry
->operator=(DenseMapInfo
<Value
*>::getTombstoneKey());
505 // Weak just goes to null, which will unlink it from the list.
509 // Forward to the subclass's implementation.
510 static_cast<CallbackVH
*>(Entry
)->deleted();
515 // All callbacks, weak references, and assertingVHs should be dropped by now.
516 if (V
->HasValueHandle
) {
517 #ifndef NDEBUG // Only in +Asserts mode...
518 dbgs() << "While deleting: " << *V
->getType() << " %" << V
->getNameStr()
520 if (pImpl
->ValueHandles
[V
]->getKind() == Assert
)
521 llvm_unreachable("An asserting value handle still pointed to this"
525 llvm_unreachable("All references to V were not removed?");
530 void ValueHandleBase::ValueIsRAUWd(Value
*Old
, Value
*New
) {
531 assert(Old
->HasValueHandle
&&"Should only be called if ValueHandles present");
532 assert(Old
!= New
&& "Changing value into itself!");
534 // Get the linked list base, which is guaranteed to exist since the
535 // HasValueHandle flag is set.
536 LLVMContextImpl
*pImpl
= Old
->getContext().pImpl
;
537 ValueHandleBase
*Entry
= pImpl
->ValueHandles
[Old
];
539 assert(Entry
&& "Value bit set but no entries exist");
541 // We use a local ValueHandleBase as an iterator so that
542 // ValueHandles can add and remove themselves from the list without
543 // breaking our iteration. This is not really an AssertingVH; we
544 // just have to give ValueHandleBase some kind.
545 for (ValueHandleBase
Iterator(Assert
, *Entry
); Entry
; Entry
= Iterator
.Next
) {
546 Iterator
.RemoveFromUseList();
547 Iterator
.AddToExistingUseListAfter(Entry
);
548 assert(Entry
->Next
== &Iterator
&& "Loop invariant broken.");
550 switch (Entry
->getKind()) {
552 // Asserting handle does not follow RAUW implicitly.
555 // Tracking goes to new value like a WeakVH. Note that this may make it
556 // something incompatible with its templated type. We don't want to have a
557 // virtual (or inline) interface to handle this though, so instead we make
558 // the TrackingVH accessors guarantee that a client never sees this value.
562 // Weak goes to the new value, which will unlink it from Old's list.
563 Entry
->operator=(New
);
566 // Forward to the subclass's implementation.
567 static_cast<CallbackVH
*>(Entry
)->allUsesReplacedWith(New
);
573 /// ~CallbackVH. Empty, but defined here to avoid emitting the vtable
575 CallbackVH::~CallbackVH() {}
578 //===----------------------------------------------------------------------===//
580 //===----------------------------------------------------------------------===//
582 // replaceUsesOfWith - Replaces all references to the "From" definition with
583 // references to the "To" definition.
585 void User::replaceUsesOfWith(Value
*From
, Value
*To
) {
586 if (From
== To
) return; // Duh what?
588 assert((!isa
<Constant
>(this) || isa
<GlobalValue
>(this)) &&
589 "Cannot call User::replaceUsesOfWith on a constant!");
591 for (unsigned i
= 0, E
= getNumOperands(); i
!= E
; ++i
)
592 if (getOperand(i
) == From
) { // Is This operand is pointing to oldval?
593 // The side effects of this setOperand call include linking to
594 // "To", adding "this" to the uses list of To, and
595 // most importantly, removing "this" from the use list of "From".
596 setOperand(i
, To
); // Fix it now...