1 //===- Metadata.cpp - Implement Metadata classes --------------------------===//
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 Metadata classes.
12 //===----------------------------------------------------------------------===//
14 #include "LLVMContextImpl.h"
15 #include "MetadataImpl.h"
16 #include "SymbolTableListTraitsImpl.h"
17 #include "llvm/ADT/APFloat.h"
18 #include "llvm/ADT/APInt.h"
19 #include "llvm/ADT/ArrayRef.h"
20 #include "llvm/ADT/DenseSet.h"
21 #include "llvm/ADT/None.h"
22 #include "llvm/ADT/STLExtras.h"
23 #include "llvm/ADT/SetVector.h"
24 #include "llvm/ADT/SmallPtrSet.h"
25 #include "llvm/ADT/SmallSet.h"
26 #include "llvm/ADT/SmallVector.h"
27 #include "llvm/ADT/StringMap.h"
28 #include "llvm/ADT/StringRef.h"
29 #include "llvm/ADT/Twine.h"
30 #include "llvm/IR/Argument.h"
31 #include "llvm/IR/BasicBlock.h"
32 #include "llvm/IR/Constant.h"
33 #include "llvm/IR/ConstantRange.h"
34 #include "llvm/IR/Constants.h"
35 #include "llvm/IR/DebugInfoMetadata.h"
36 #include "llvm/IR/DebugLoc.h"
37 #include "llvm/IR/Function.h"
38 #include "llvm/IR/GlobalObject.h"
39 #include "llvm/IR/GlobalVariable.h"
40 #include "llvm/IR/Instruction.h"
41 #include "llvm/IR/LLVMContext.h"
42 #include "llvm/IR/Metadata.h"
43 #include "llvm/IR/Module.h"
44 #include "llvm/IR/TrackingMDRef.h"
45 #include "llvm/IR/Type.h"
46 #include "llvm/IR/Value.h"
47 #include "llvm/IR/ValueHandle.h"
48 #include "llvm/Support/Casting.h"
49 #include "llvm/Support/ErrorHandling.h"
50 #include "llvm/Support/MathExtras.h"
57 #include <type_traits>
63 MetadataAsValue::MetadataAsValue(Type *Ty, Metadata *MD)
64 : Value(Ty, MetadataAsValueVal), MD(MD) {
68 MetadataAsValue::~MetadataAsValue() {
69 getType()->getContext().pImpl->MetadataAsValues.erase(MD);
73 /// Canonicalize metadata arguments to intrinsics.
75 /// To support bitcode upgrades (and assembly semantic sugar) for \a
76 /// MetadataAsValue, we need to canonicalize certain metadata.
78 /// - nullptr is replaced by an empty MDNode.
79 /// - An MDNode with a single null operand is replaced by an empty MDNode.
80 /// - An MDNode whose only operand is a \a ConstantAsMetadata gets skipped.
82 /// This maintains readability of bitcode from when metadata was a type of
83 /// value, and these bridges were unnecessary.
84 static Metadata *canonicalizeMetadataForValue(LLVMContext &Context,
88 return MDNode::get(Context, None);
90 // Return early if this isn't a single-operand MDNode.
91 auto *N = dyn_cast<MDNode>(MD);
92 if (!N || N->getNumOperands() != 1)
95 if (!N->getOperand(0))
97 return MDNode::get(Context, None);
99 if (auto *C = dyn_cast<ConstantAsMetadata>(N->getOperand(0)))
100 // Look through the MDNode.
106 MetadataAsValue *MetadataAsValue::get(LLVMContext &Context, Metadata *MD) {
107 MD = canonicalizeMetadataForValue(Context, MD);
108 auto *&Entry = Context.pImpl->MetadataAsValues[MD];
110 Entry = new MetadataAsValue(Type::getMetadataTy(Context), MD);
114 MetadataAsValue *MetadataAsValue::getIfExists(LLVMContext &Context,
116 MD = canonicalizeMetadataForValue(Context, MD);
117 auto &Store = Context.pImpl->MetadataAsValues;
118 return Store.lookup(MD);
121 void MetadataAsValue::handleChangedMetadata(Metadata *MD) {
122 LLVMContext &Context = getContext();
123 MD = canonicalizeMetadataForValue(Context, MD);
124 auto &Store = Context.pImpl->MetadataAsValues;
126 // Stop tracking the old metadata.
127 Store.erase(this->MD);
131 // Start tracking MD, or RAUW if necessary.
132 auto *&Entry = Store[MD];
134 replaceAllUsesWith(Entry);
144 void MetadataAsValue::track() {
146 MetadataTracking::track(&MD, *MD, *this);
149 void MetadataAsValue::untrack() {
151 MetadataTracking::untrack(MD);
154 bool MetadataTracking::track(void *Ref, Metadata &MD, OwnerTy Owner) {
155 assert(Ref && "Expected live reference");
156 assert((Owner || *static_cast<Metadata **>(Ref) == &MD) &&
157 "Reference without owner must be direct");
158 if (auto *R = ReplaceableMetadataImpl::getOrCreate(MD)) {
159 R->addRef(Ref, Owner);
162 if (auto *PH = dyn_cast<DistinctMDOperandPlaceholder>(&MD)) {
163 assert(!PH->Use && "Placeholders can only be used once");
164 assert(!Owner && "Unexpected callback to owner");
165 PH->Use = static_cast<Metadata **>(Ref);
171 void MetadataTracking::untrack(void *Ref, Metadata &MD) {
172 assert(Ref && "Expected live reference");
173 if (auto *R = ReplaceableMetadataImpl::getIfExists(MD))
175 else if (auto *PH = dyn_cast<DistinctMDOperandPlaceholder>(&MD))
179 bool MetadataTracking::retrack(void *Ref, Metadata &MD, void *New) {
180 assert(Ref && "Expected live reference");
181 assert(New && "Expected live reference");
182 assert(Ref != New && "Expected change");
183 if (auto *R = ReplaceableMetadataImpl::getIfExists(MD)) {
184 R->moveRef(Ref, New, MD);
187 assert(!isa<DistinctMDOperandPlaceholder>(MD) &&
188 "Unexpected move of an MDOperand");
189 assert(!isReplaceable(MD) &&
190 "Expected un-replaceable metadata, since we didn't move a reference");
194 bool MetadataTracking::isReplaceable(const Metadata &MD) {
195 return ReplaceableMetadataImpl::isReplaceable(MD);
198 void ReplaceableMetadataImpl::addRef(void *Ref, OwnerTy Owner) {
200 UseMap.insert(std::make_pair(Ref, std::make_pair(Owner, NextIndex)))
203 assert(WasInserted && "Expected to add a reference");
206 assert(NextIndex != 0 && "Unexpected overflow");
209 void ReplaceableMetadataImpl::dropRef(void *Ref) {
210 bool WasErased = UseMap.erase(Ref);
212 assert(WasErased && "Expected to drop a reference");
215 void ReplaceableMetadataImpl::moveRef(void *Ref, void *New,
216 const Metadata &MD) {
217 auto I = UseMap.find(Ref);
218 assert(I != UseMap.end() && "Expected to move a reference");
219 auto OwnerAndIndex = I->second;
221 bool WasInserted = UseMap.insert(std::make_pair(New, OwnerAndIndex)).second;
223 assert(WasInserted && "Expected to add a reference");
225 // Check that the references are direct if there's no owner.
227 assert((OwnerAndIndex.first || *static_cast<Metadata **>(Ref) == &MD) &&
228 "Reference without owner must be direct");
229 assert((OwnerAndIndex.first || *static_cast<Metadata **>(New) == &MD) &&
230 "Reference without owner must be direct");
233 void ReplaceableMetadataImpl::replaceAllUsesWith(Metadata *MD) {
237 // Copy out uses since UseMap will get touched below.
238 using UseTy = std::pair<void *, std::pair<OwnerTy, uint64_t>>;
239 SmallVector<UseTy, 8> Uses(UseMap.begin(), UseMap.end());
240 std::sort(Uses.begin(), Uses.end(), [](const UseTy &L, const UseTy &R) {
241 return L.second.second < R.second.second;
243 for (const auto &Pair : Uses) {
244 // Check that this Ref hasn't disappeared after RAUW (when updating a
246 if (!UseMap.count(Pair.first))
249 OwnerTy Owner = Pair.second.first;
251 // Update unowned tracking references directly.
252 Metadata *&Ref = *static_cast<Metadata **>(Pair.first);
255 MetadataTracking::track(Ref);
256 UseMap.erase(Pair.first);
260 // Check for MetadataAsValue.
261 if (Owner.is<MetadataAsValue *>()) {
262 Owner.get<MetadataAsValue *>()->handleChangedMetadata(MD);
266 // There's a Metadata owner -- dispatch.
267 Metadata *OwnerMD = Owner.get<Metadata *>();
268 switch (OwnerMD->getMetadataID()) {
269 #define HANDLE_METADATA_LEAF(CLASS) \
270 case Metadata::CLASS##Kind: \
271 cast<CLASS>(OwnerMD)->handleChangedOperand(Pair.first, MD); \
273 #include "llvm/IR/Metadata.def"
275 llvm_unreachable("Invalid metadata subclass");
278 assert(UseMap.empty() && "Expected all uses to be replaced");
281 void ReplaceableMetadataImpl::resolveAllUses(bool ResolveUsers) {
290 // Copy out uses since UseMap could get touched below.
291 using UseTy = std::pair<void *, std::pair<OwnerTy, uint64_t>>;
292 SmallVector<UseTy, 8> Uses(UseMap.begin(), UseMap.end());
293 std::sort(Uses.begin(), Uses.end(), [](const UseTy &L, const UseTy &R) {
294 return L.second.second < R.second.second;
297 for (const auto &Pair : Uses) {
298 auto Owner = Pair.second.first;
301 if (Owner.is<MetadataAsValue *>())
304 // Resolve MDNodes that point at this.
305 auto *OwnerMD = dyn_cast<MDNode>(Owner.get<Metadata *>());
308 if (OwnerMD->isResolved())
310 OwnerMD->decrementUnresolvedOperandCount();
314 ReplaceableMetadataImpl *ReplaceableMetadataImpl::getOrCreate(Metadata &MD) {
315 if (auto *N = dyn_cast<MDNode>(&MD))
316 return N->isResolved() ? nullptr : N->Context.getOrCreateReplaceableUses();
317 return dyn_cast<ValueAsMetadata>(&MD);
320 ReplaceableMetadataImpl *ReplaceableMetadataImpl::getIfExists(Metadata &MD) {
321 if (auto *N = dyn_cast<MDNode>(&MD))
322 return N->isResolved() ? nullptr : N->Context.getReplaceableUses();
323 return dyn_cast<ValueAsMetadata>(&MD);
326 bool ReplaceableMetadataImpl::isReplaceable(const Metadata &MD) {
327 if (auto *N = dyn_cast<MDNode>(&MD))
328 return !N->isResolved();
329 return dyn_cast<ValueAsMetadata>(&MD);
332 static Function *getLocalFunction(Value *V) {
333 assert(V && "Expected value");
334 if (auto *A = dyn_cast<Argument>(V))
335 return A->getParent();
336 if (BasicBlock *BB = cast<Instruction>(V)->getParent())
337 return BB->getParent();
341 ValueAsMetadata *ValueAsMetadata::get(Value *V) {
342 assert(V && "Unexpected null Value");
344 auto &Context = V->getContext();
345 auto *&Entry = Context.pImpl->ValuesAsMetadata[V];
347 assert((isa<Constant>(V) || isa<Argument>(V) || isa<Instruction>(V)) &&
348 "Expected constant or function-local value");
349 assert(!V->IsUsedByMD && "Expected this to be the only metadata use");
350 V->IsUsedByMD = true;
351 if (auto *C = dyn_cast<Constant>(V))
352 Entry = new ConstantAsMetadata(C);
354 Entry = new LocalAsMetadata(V);
360 ValueAsMetadata *ValueAsMetadata::getIfExists(Value *V) {
361 assert(V && "Unexpected null Value");
362 return V->getContext().pImpl->ValuesAsMetadata.lookup(V);
365 void ValueAsMetadata::handleDeletion(Value *V) {
366 assert(V && "Expected valid value");
368 auto &Store = V->getType()->getContext().pImpl->ValuesAsMetadata;
369 auto I = Store.find(V);
370 if (I == Store.end())
373 // Remove old entry from the map.
374 ValueAsMetadata *MD = I->second;
375 assert(MD && "Expected valid metadata");
376 assert(MD->getValue() == V && "Expected valid mapping");
379 // Delete the metadata.
380 MD->replaceAllUsesWith(nullptr);
384 void ValueAsMetadata::handleRAUW(Value *From, Value *To) {
385 assert(From && "Expected valid value");
386 assert(To && "Expected valid value");
387 assert(From != To && "Expected changed value");
388 assert(From->getType() == To->getType() && "Unexpected type change");
390 LLVMContext &Context = From->getType()->getContext();
391 auto &Store = Context.pImpl->ValuesAsMetadata;
392 auto I = Store.find(From);
393 if (I == Store.end()) {
394 assert(!From->IsUsedByMD && "Expected From not to be used by metadata");
398 // Remove old entry from the map.
399 assert(From->IsUsedByMD && "Expected From to be used by metadata");
400 From->IsUsedByMD = false;
401 ValueAsMetadata *MD = I->second;
402 assert(MD && "Expected valid metadata");
403 assert(MD->getValue() == From && "Expected valid mapping");
406 if (isa<LocalAsMetadata>(MD)) {
407 if (auto *C = dyn_cast<Constant>(To)) {
408 // Local became a constant.
409 MD->replaceAllUsesWith(ConstantAsMetadata::get(C));
413 if (getLocalFunction(From) && getLocalFunction(To) &&
414 getLocalFunction(From) != getLocalFunction(To)) {
416 MD->replaceAllUsesWith(nullptr);
420 } else if (!isa<Constant>(To)) {
421 // Changed to function-local value.
422 MD->replaceAllUsesWith(nullptr);
427 auto *&Entry = Store[To];
429 // The target already exists.
430 MD->replaceAllUsesWith(Entry);
435 // Update MD in place (and update the map entry).
436 assert(!To->IsUsedByMD && "Expected this to be the only metadata use");
437 To->IsUsedByMD = true;
442 //===----------------------------------------------------------------------===//
443 // MDString implementation.
446 MDString *MDString::get(LLVMContext &Context, StringRef Str) {
447 auto &Store = Context.pImpl->MDStringCache;
448 auto I = Store.try_emplace(Str);
449 auto &MapEntry = I.first->getValue();
452 MapEntry.Entry = &*I.first;
456 StringRef MDString::getString() const {
457 assert(Entry && "Expected to find string map entry");
458 return Entry->first();
461 //===----------------------------------------------------------------------===//
462 // MDNode implementation.
465 // Assert that the MDNode types will not be unaligned by the objects
466 // prepended to them.
467 #define HANDLE_MDNODE_LEAF(CLASS) \
469 alignof(uint64_t) >= alignof(CLASS), \
470 "Alignment is insufficient after objects prepended to " #CLASS);
471 #include "llvm/IR/Metadata.def"
473 void *MDNode::operator new(size_t Size, unsigned NumOps) {
474 size_t OpSize = NumOps * sizeof(MDOperand);
475 // uint64_t is the most aligned type we need support (ensured by static_assert
477 OpSize = alignTo(OpSize, alignof(uint64_t));
478 void *Ptr = reinterpret_cast<char *>(::operator new(OpSize + Size)) + OpSize;
479 MDOperand *O = static_cast<MDOperand *>(Ptr);
480 for (MDOperand *E = O - NumOps; O != E; --O)
481 (void)new (O - 1) MDOperand;
485 void MDNode::operator delete(void *Mem) {
486 MDNode *N = static_cast<MDNode *>(Mem);
487 size_t OpSize = N->NumOperands * sizeof(MDOperand);
488 OpSize = alignTo(OpSize, alignof(uint64_t));
490 MDOperand *O = static_cast<MDOperand *>(Mem);
491 for (MDOperand *E = O - N->NumOperands; O != E; --O)
492 (O - 1)->~MDOperand();
493 ::operator delete(reinterpret_cast<char *>(Mem) - OpSize);
496 MDNode::MDNode(LLVMContext &Context, unsigned ID, StorageType Storage,
497 ArrayRef<Metadata *> Ops1, ArrayRef<Metadata *> Ops2)
498 : Metadata(ID, Storage), NumOperands(Ops1.size() + Ops2.size()),
499 NumUnresolved(0), Context(Context) {
501 for (Metadata *MD : Ops1)
502 setOperand(Op++, MD);
503 for (Metadata *MD : Ops2)
504 setOperand(Op++, MD);
509 // Count the unresolved operands. If there are any, RAUW support will be
510 // added lazily on first reference.
511 countUnresolvedOperands();
514 TempMDNode MDNode::clone() const {
515 switch (getMetadataID()) {
517 llvm_unreachable("Invalid MDNode subclass");
518 #define HANDLE_MDNODE_LEAF(CLASS) \
520 return cast<CLASS>(this)->cloneImpl();
521 #include "llvm/IR/Metadata.def"
525 static bool isOperandUnresolved(Metadata *Op) {
526 if (auto *N = dyn_cast_or_null<MDNode>(Op))
527 return !N->isResolved();
531 void MDNode::countUnresolvedOperands() {
532 assert(NumUnresolved == 0 && "Expected unresolved ops to be uncounted");
533 assert(isUniqued() && "Expected this to be uniqued");
534 NumUnresolved = count_if(operands(), isOperandUnresolved);
537 void MDNode::makeUniqued() {
538 assert(isTemporary() && "Expected this to be temporary");
539 assert(!isResolved() && "Expected this to be unresolved");
541 // Enable uniquing callbacks.
542 for (auto &Op : mutable_operands())
543 Op.reset(Op.get(), this);
545 // Make this 'uniqued'.
547 countUnresolvedOperands();
548 if (!NumUnresolved) {
549 dropReplaceableUses();
550 assert(isResolved() && "Expected this to be resolved");
553 assert(isUniqued() && "Expected this to be uniqued");
556 void MDNode::makeDistinct() {
557 assert(isTemporary() && "Expected this to be temporary");
558 assert(!isResolved() && "Expected this to be unresolved");
560 // Drop RAUW support and store as a distinct node.
561 dropReplaceableUses();
562 storeDistinctInContext();
564 assert(isDistinct() && "Expected this to be distinct");
565 assert(isResolved() && "Expected this to be resolved");
568 void MDNode::resolve() {
569 assert(isUniqued() && "Expected this to be uniqued");
570 assert(!isResolved() && "Expected this to be unresolved");
573 dropReplaceableUses();
575 assert(isResolved() && "Expected this to be resolved");
578 void MDNode::dropReplaceableUses() {
579 assert(!NumUnresolved && "Unexpected unresolved operand");
581 // Drop any RAUW support.
582 if (Context.hasReplaceableUses())
583 Context.takeReplaceableUses()->resolveAllUses();
586 void MDNode::resolveAfterOperandChange(Metadata *Old, Metadata *New) {
587 assert(isUniqued() && "Expected this to be uniqued");
588 assert(NumUnresolved != 0 && "Expected unresolved operands");
590 // Check if an operand was resolved.
591 if (!isOperandUnresolved(Old)) {
592 if (isOperandUnresolved(New))
593 // An operand was un-resolved!
595 } else if (!isOperandUnresolved(New))
596 decrementUnresolvedOperandCount();
599 void MDNode::decrementUnresolvedOperandCount() {
600 assert(!isResolved() && "Expected this to be unresolved");
604 assert(isUniqued() && "Expected this to be uniqued");
608 // Last unresolved operand has just been resolved.
609 dropReplaceableUses();
610 assert(isResolved() && "Expected this to become resolved");
613 void MDNode::resolveCycles() {
617 // Resolve this node immediately.
620 // Resolve all operands.
621 for (const auto &Op : operands()) {
622 auto *N = dyn_cast_or_null<MDNode>(Op);
626 assert(!N->isTemporary() &&
627 "Expected all forward declarations to be resolved");
628 if (!N->isResolved())
633 static bool hasSelfReference(MDNode *N) {
634 for (Metadata *MD : N->operands())
640 MDNode *MDNode::replaceWithPermanentImpl() {
641 switch (getMetadataID()) {
643 // If this type isn't uniquable, replace with a distinct node.
644 return replaceWithDistinctImpl();
646 #define HANDLE_MDNODE_LEAF_UNIQUABLE(CLASS) \
649 #include "llvm/IR/Metadata.def"
652 // Even if this type is uniquable, self-references have to be distinct.
653 if (hasSelfReference(this))
654 return replaceWithDistinctImpl();
655 return replaceWithUniquedImpl();
658 MDNode *MDNode::replaceWithUniquedImpl() {
659 // Try to uniquify in place.
660 MDNode *UniquedNode = uniquify();
662 if (UniquedNode == this) {
667 // Collision, so RAUW instead.
668 replaceAllUsesWith(UniquedNode);
673 MDNode *MDNode::replaceWithDistinctImpl() {
678 void MDTuple::recalculateHash() {
679 setHash(MDTupleInfo::KeyTy::calculateHash(this));
682 void MDNode::dropAllReferences() {
683 for (unsigned I = 0, E = NumOperands; I != E; ++I)
684 setOperand(I, nullptr);
685 if (Context.hasReplaceableUses()) {
686 Context.getReplaceableUses()->resolveAllUses(/* ResolveUsers */ false);
687 (void)Context.takeReplaceableUses();
691 void MDNode::handleChangedOperand(void *Ref, Metadata *New) {
692 unsigned Op = static_cast<MDOperand *>(Ref) - op_begin();
693 assert(Op < getNumOperands() && "Expected valid operand");
696 // This node is not uniqued. Just set the operand and be done with it.
701 // This node is uniqued.
704 Metadata *Old = getOperand(Op);
707 // Drop uniquing for self-reference cycles and deleted constants.
708 if (New == this || (!New && Old && isa<ConstantAsMetadata>(Old))) {
711 storeDistinctInContext();
715 // Re-unique the node.
716 auto *Uniqued = uniquify();
717 if (Uniqued == this) {
719 resolveAfterOperandChange(Old, New);
725 // Still unresolved, so RAUW.
727 // First, clear out all operands to prevent any recursion (similar to
728 // dropAllReferences(), but we still need the use-list).
729 for (unsigned O = 0, E = getNumOperands(); O != E; ++O)
730 setOperand(O, nullptr);
731 if (Context.hasReplaceableUses())
732 Context.getReplaceableUses()->replaceAllUsesWith(Uniqued);
737 // Store in non-uniqued form if RAUW isn't possible.
738 storeDistinctInContext();
741 void MDNode::deleteAsSubclass() {
742 switch (getMetadataID()) {
744 llvm_unreachable("Invalid subclass of MDNode");
745 #define HANDLE_MDNODE_LEAF(CLASS) \
747 delete cast<CLASS>(this); \
749 #include "llvm/IR/Metadata.def"
753 template <class T, class InfoT>
754 static T *uniquifyImpl(T *N, DenseSet<T *, InfoT> &Store) {
755 if (T *U = getUniqued(Store, N))
762 template <class NodeTy> struct MDNode::HasCachedHash {
765 template <class U, U Val> struct SFINAE {};
768 static Yes &check(SFINAE<void (U::*)(unsigned), &U::setHash> *);
769 template <class U> static No &check(...);
771 static const bool value = sizeof(check<NodeTy>(nullptr)) == sizeof(Yes);
774 MDNode *MDNode::uniquify() {
775 assert(!hasSelfReference(this) && "Cannot uniquify a self-referencing node");
777 // Try to insert into uniquing store.
778 switch (getMetadataID()) {
780 llvm_unreachable("Invalid or non-uniquable subclass of MDNode");
781 #define HANDLE_MDNODE_LEAF_UNIQUABLE(CLASS) \
782 case CLASS##Kind: { \
783 CLASS *SubclassThis = cast<CLASS>(this); \
784 std::integral_constant<bool, HasCachedHash<CLASS>::value> \
785 ShouldRecalculateHash; \
786 dispatchRecalculateHash(SubclassThis, ShouldRecalculateHash); \
787 return uniquifyImpl(SubclassThis, getContext().pImpl->CLASS##s); \
789 #include "llvm/IR/Metadata.def"
793 void MDNode::eraseFromStore() {
794 switch (getMetadataID()) {
796 llvm_unreachable("Invalid or non-uniquable subclass of MDNode");
797 #define HANDLE_MDNODE_LEAF_UNIQUABLE(CLASS) \
799 getContext().pImpl->CLASS##s.erase(cast<CLASS>(this)); \
801 #include "llvm/IR/Metadata.def"
805 MDTuple *MDTuple::getImpl(LLVMContext &Context, ArrayRef<Metadata *> MDs,
806 StorageType Storage, bool ShouldCreate) {
808 if (Storage == Uniqued) {
809 MDTupleInfo::KeyTy Key(MDs);
810 if (auto *N = getUniqued(Context.pImpl->MDTuples, Key))
814 Hash = Key.getHash();
816 assert(ShouldCreate && "Expected non-uniqued nodes to always be created");
819 return storeImpl(new (MDs.size()) MDTuple(Context, Storage, Hash, MDs),
820 Storage, Context.pImpl->MDTuples);
823 void MDNode::deleteTemporary(MDNode *N) {
824 assert(N->isTemporary() && "Expected temporary node");
825 N->replaceAllUsesWith(nullptr);
826 N->deleteAsSubclass();
829 void MDNode::storeDistinctInContext() {
830 assert(!Context.hasReplaceableUses() && "Unexpected replaceable uses");
831 assert(!NumUnresolved && "Unexpected unresolved nodes");
833 assert(isResolved() && "Expected this to be resolved");
836 switch (getMetadataID()) {
838 llvm_unreachable("Invalid subclass of MDNode");
839 #define HANDLE_MDNODE_LEAF(CLASS) \
840 case CLASS##Kind: { \
841 std::integral_constant<bool, HasCachedHash<CLASS>::value> ShouldResetHash; \
842 dispatchResetHash(cast<CLASS>(this), ShouldResetHash); \
845 #include "llvm/IR/Metadata.def"
848 getContext().pImpl->DistinctMDNodes.push_back(this);
851 void MDNode::replaceOperandWith(unsigned I, Metadata *New) {
852 if (getOperand(I) == New)
860 handleChangedOperand(mutable_begin() + I, New);
863 void MDNode::setOperand(unsigned I, Metadata *New) {
864 assert(I < NumOperands);
865 mutable_begin()[I].reset(New, isUniqued() ? this : nullptr);
868 /// Get a node or a self-reference that looks like it.
870 /// Special handling for finding self-references, for use by \a
871 /// MDNode::concatenate() and \a MDNode::intersect() to maintain behaviour from
872 /// when self-referencing nodes were still uniqued. If the first operand has
873 /// the same operands as \c Ops, return the first operand instead.
874 static MDNode *getOrSelfReference(LLVMContext &Context,
875 ArrayRef<Metadata *> Ops) {
877 if (MDNode *N = dyn_cast_or_null<MDNode>(Ops[0]))
878 if (N->getNumOperands() == Ops.size() && N == N->getOperand(0)) {
879 for (unsigned I = 1, E = Ops.size(); I != E; ++I)
880 if (Ops[I] != N->getOperand(I))
881 return MDNode::get(Context, Ops);
885 return MDNode::get(Context, Ops);
888 MDNode *MDNode::concatenate(MDNode *A, MDNode *B) {
894 SmallSetVector<Metadata *, 4> MDs(A->op_begin(), A->op_end());
895 MDs.insert(B->op_begin(), B->op_end());
897 // FIXME: This preserves long-standing behaviour, but is it really the right
898 // behaviour? Or was that an unintended side-effect of node uniquing?
899 return getOrSelfReference(A->getContext(), MDs.getArrayRef());
902 MDNode *MDNode::intersect(MDNode *A, MDNode *B) {
906 SmallSetVector<Metadata *, 4> MDs(A->op_begin(), A->op_end());
907 SmallPtrSet<Metadata *, 4> BSet(B->op_begin(), B->op_end());
908 MDs.remove_if([&](Metadata *MD) { return !is_contained(BSet, MD); });
910 // FIXME: This preserves long-standing behaviour, but is it really the right
911 // behaviour? Or was that an unintended side-effect of node uniquing?
912 return getOrSelfReference(A->getContext(), MDs.getArrayRef());
915 MDNode *MDNode::getMostGenericAliasScope(MDNode *A, MDNode *B) {
919 return concatenate(A, B);
922 MDNode *MDNode::getMostGenericFPMath(MDNode *A, MDNode *B) {
926 APFloat AVal = mdconst::extract<ConstantFP>(A->getOperand(0))->getValueAPF();
927 APFloat BVal = mdconst::extract<ConstantFP>(B->getOperand(0))->getValueAPF();
928 if (AVal.compare(BVal) == APFloat::cmpLessThan)
933 static bool isContiguous(const ConstantRange &A, const ConstantRange &B) {
934 return A.getUpper() == B.getLower() || A.getLower() == B.getUpper();
937 static bool canBeMerged(const ConstantRange &A, const ConstantRange &B) {
938 return !A.intersectWith(B).isEmptySet() || isContiguous(A, B);
941 static bool tryMergeRange(SmallVectorImpl<ConstantInt *> &EndPoints,
942 ConstantInt *Low, ConstantInt *High) {
943 ConstantRange NewRange(Low->getValue(), High->getValue());
944 unsigned Size = EndPoints.size();
945 APInt LB = EndPoints[Size - 2]->getValue();
946 APInt LE = EndPoints[Size - 1]->getValue();
947 ConstantRange LastRange(LB, LE);
948 if (canBeMerged(NewRange, LastRange)) {
949 ConstantRange Union = LastRange.unionWith(NewRange);
950 Type *Ty = High->getType();
951 EndPoints[Size - 2] =
952 cast<ConstantInt>(ConstantInt::get(Ty, Union.getLower()));
953 EndPoints[Size - 1] =
954 cast<ConstantInt>(ConstantInt::get(Ty, Union.getUpper()));
960 static void addRange(SmallVectorImpl<ConstantInt *> &EndPoints,
961 ConstantInt *Low, ConstantInt *High) {
962 if (!EndPoints.empty())
963 if (tryMergeRange(EndPoints, Low, High))
966 EndPoints.push_back(Low);
967 EndPoints.push_back(High);
970 MDNode *MDNode::getMostGenericRange(MDNode *A, MDNode *B) {
971 // Given two ranges, we want to compute the union of the ranges. This
972 // is slightly complicated by having to combine the intervals and merge
973 // the ones that overlap.
981 // First, walk both lists in order of the lower boundary of each interval.
982 // At each step, try to merge the new interval to the last one we adedd.
983 SmallVector<ConstantInt *, 4> EndPoints;
986 int AN = A->getNumOperands() / 2;
987 int BN = B->getNumOperands() / 2;
988 while (AI < AN && BI < BN) {
989 ConstantInt *ALow = mdconst::extract<ConstantInt>(A->getOperand(2 * AI));
990 ConstantInt *BLow = mdconst::extract<ConstantInt>(B->getOperand(2 * BI));
992 if (ALow->getValue().slt(BLow->getValue())) {
993 addRange(EndPoints, ALow,
994 mdconst::extract<ConstantInt>(A->getOperand(2 * AI + 1)));
997 addRange(EndPoints, BLow,
998 mdconst::extract<ConstantInt>(B->getOperand(2 * BI + 1)));
1003 addRange(EndPoints, mdconst::extract<ConstantInt>(A->getOperand(2 * AI)),
1004 mdconst::extract<ConstantInt>(A->getOperand(2 * AI + 1)));
1008 addRange(EndPoints, mdconst::extract<ConstantInt>(B->getOperand(2 * BI)),
1009 mdconst::extract<ConstantInt>(B->getOperand(2 * BI + 1)));
1013 // If we have more than 2 ranges (4 endpoints) we have to try to merge
1014 // the last and first ones.
1015 unsigned Size = EndPoints.size();
1017 ConstantInt *FB = EndPoints[0];
1018 ConstantInt *FE = EndPoints[1];
1019 if (tryMergeRange(EndPoints, FB, FE)) {
1020 for (unsigned i = 0; i < Size - 2; ++i) {
1021 EndPoints[i] = EndPoints[i + 2];
1023 EndPoints.resize(Size - 2);
1027 // If in the end we have a single range, it is possible that it is now the
1028 // full range. Just drop the metadata in that case.
1029 if (EndPoints.size() == 2) {
1030 ConstantRange Range(EndPoints[0]->getValue(), EndPoints[1]->getValue());
1031 if (Range.isFullSet())
1035 SmallVector<Metadata *, 4> MDs;
1036 MDs.reserve(EndPoints.size());
1037 for (auto *I : EndPoints)
1038 MDs.push_back(ConstantAsMetadata::get(I));
1039 return MDNode::get(A->getContext(), MDs);
1042 MDNode *MDNode::getMostGenericAlignmentOrDereferenceable(MDNode *A, MDNode *B) {
1046 ConstantInt *AVal = mdconst::extract<ConstantInt>(A->getOperand(0));
1047 ConstantInt *BVal = mdconst::extract<ConstantInt>(B->getOperand(0));
1048 if (AVal->getZExtValue() < BVal->getZExtValue())
1053 //===----------------------------------------------------------------------===//
1054 // NamedMDNode implementation.
1057 static SmallVector<TrackingMDRef, 4> &getNMDOps(void *Operands) {
1058 return *(SmallVector<TrackingMDRef, 4> *)Operands;
1061 NamedMDNode::NamedMDNode(const Twine &N)
1062 : Name(N.str()), Operands(new SmallVector<TrackingMDRef, 4>()) {}
1064 NamedMDNode::~NamedMDNode() {
1065 dropAllReferences();
1066 delete &getNMDOps(Operands);
1069 unsigned NamedMDNode::getNumOperands() const {
1070 return (unsigned)getNMDOps(Operands).size();
1073 MDNode *NamedMDNode::getOperand(unsigned i) const {
1074 assert(i < getNumOperands() && "Invalid Operand number!");
1075 auto *N = getNMDOps(Operands)[i].get();
1076 return cast_or_null<MDNode>(N);
1079 void NamedMDNode::addOperand(MDNode *M) { getNMDOps(Operands).emplace_back(M); }
1081 void NamedMDNode::setOperand(unsigned I, MDNode *New) {
1082 assert(I < getNumOperands() && "Invalid operand number");
1083 getNMDOps(Operands)[I].reset(New);
1086 void NamedMDNode::eraseFromParent() { getParent()->eraseNamedMetadata(this); }
1088 void NamedMDNode::clearOperands() { getNMDOps(Operands).clear(); }
1090 StringRef NamedMDNode::getName() const { return StringRef(Name); }
1092 //===----------------------------------------------------------------------===//
1093 // Instruction Metadata method implementations.
1095 void MDAttachmentMap::set(unsigned ID, MDNode &MD) {
1096 for (auto &I : Attachments)
1097 if (I.first == ID) {
1098 I.second.reset(&MD);
1101 Attachments.emplace_back(std::piecewise_construct, std::make_tuple(ID),
1102 std::make_tuple(&MD));
1105 void MDAttachmentMap::erase(unsigned ID) {
1109 // Common case is one/last value.
1110 if (Attachments.back().first == ID) {
1111 Attachments.pop_back();
1115 for (auto I = Attachments.begin(), E = std::prev(Attachments.end()); I != E;
1117 if (I->first == ID) {
1118 *I = std::move(Attachments.back());
1119 Attachments.pop_back();
1124 MDNode *MDAttachmentMap::lookup(unsigned ID) const {
1125 for (const auto &I : Attachments)
1131 void MDAttachmentMap::getAll(
1132 SmallVectorImpl<std::pair<unsigned, MDNode *>> &Result) const {
1133 Result.append(Attachments.begin(), Attachments.end());
1135 // Sort the resulting array so it is stable.
1136 if (Result.size() > 1)
1137 array_pod_sort(Result.begin(), Result.end());
1140 void MDGlobalAttachmentMap::insert(unsigned ID, MDNode &MD) {
1141 Attachments.push_back({ID, TrackingMDNodeRef(&MD)});
1144 void MDGlobalAttachmentMap::get(unsigned ID,
1145 SmallVectorImpl<MDNode *> &Result) {
1146 for (auto A : Attachments)
1148 Result.push_back(A.Node);
1151 void MDGlobalAttachmentMap::erase(unsigned ID) {
1152 auto Follower = Attachments.begin();
1153 for (auto Leader = Attachments.begin(), E = Attachments.end(); Leader != E;
1155 if (Leader->MDKind != ID) {
1156 if (Follower != Leader)
1157 *Follower = std::move(*Leader);
1161 Attachments.resize(Follower - Attachments.begin());
1164 void MDGlobalAttachmentMap::getAll(
1165 SmallVectorImpl<std::pair<unsigned, MDNode *>> &Result) const {
1166 for (auto &A : Attachments)
1167 Result.emplace_back(A.MDKind, A.Node);
1169 // Sort the resulting array so it is stable with respect to metadata IDs. We
1170 // need to preserve the original insertion order though.
1172 Result.begin(), Result.end(),
1173 [](const std::pair<unsigned, MDNode *> &A,
1174 const std::pair<unsigned, MDNode *> &B) { return A.first < B.first; });
1177 void Instruction::setMetadata(StringRef Kind, MDNode *Node) {
1178 if (!Node && !hasMetadata())
1180 setMetadata(getContext().getMDKindID(Kind), Node);
1183 MDNode *Instruction::getMetadataImpl(StringRef Kind) const {
1184 return getMetadataImpl(getContext().getMDKindID(Kind));
1187 void Instruction::dropUnknownNonDebugMetadata(ArrayRef<unsigned> KnownIDs) {
1188 if (!hasMetadataHashEntry())
1189 return; // Nothing to remove!
1191 auto &InstructionMetadata = getContext().pImpl->InstructionMetadata;
1193 SmallSet<unsigned, 4> KnownSet;
1194 KnownSet.insert(KnownIDs.begin(), KnownIDs.end());
1195 if (KnownSet.empty()) {
1196 // Just drop our entry at the store.
1197 InstructionMetadata.erase(this);
1198 setHasMetadataHashEntry(false);
1202 auto &Info = InstructionMetadata[this];
1203 Info.remove_if([&KnownSet](const std::pair<unsigned, TrackingMDNodeRef> &I) {
1204 return !KnownSet.count(I.first);
1208 // Drop our entry at the store.
1209 InstructionMetadata.erase(this);
1210 setHasMetadataHashEntry(false);
1214 void Instruction::setMetadata(unsigned KindID, MDNode *Node) {
1215 if (!Node && !hasMetadata())
1218 // Handle 'dbg' as a special case since it is not stored in the hash table.
1219 if (KindID == LLVMContext::MD_dbg) {
1220 DbgLoc = DebugLoc(Node);
1224 // Handle the case when we're adding/updating metadata on an instruction.
1226 auto &Info = getContext().pImpl->InstructionMetadata[this];
1227 assert(!Info.empty() == hasMetadataHashEntry() &&
1228 "HasMetadata bit is wonked");
1230 setHasMetadataHashEntry(true);
1231 Info.set(KindID, *Node);
1235 // Otherwise, we're removing metadata from an instruction.
1236 assert((hasMetadataHashEntry() ==
1237 (getContext().pImpl->InstructionMetadata.count(this) > 0)) &&
1238 "HasMetadata bit out of date!");
1239 if (!hasMetadataHashEntry())
1240 return; // Nothing to remove!
1241 auto &Info = getContext().pImpl->InstructionMetadata[this];
1243 // Handle removal of an existing value.
1249 getContext().pImpl->InstructionMetadata.erase(this);
1250 setHasMetadataHashEntry(false);
1253 void Instruction::setAAMetadata(const AAMDNodes &N) {
1254 setMetadata(LLVMContext::MD_tbaa, N.TBAA);
1255 setMetadata(LLVMContext::MD_alias_scope, N.Scope);
1256 setMetadata(LLVMContext::MD_noalias, N.NoAlias);
1259 MDNode *Instruction::getMetadataImpl(unsigned KindID) const {
1260 // Handle 'dbg' as a special case since it is not stored in the hash table.
1261 if (KindID == LLVMContext::MD_dbg)
1262 return DbgLoc.getAsMDNode();
1264 if (!hasMetadataHashEntry())
1266 auto &Info = getContext().pImpl->InstructionMetadata[this];
1267 assert(!Info.empty() && "bit out of sync with hash table");
1269 return Info.lookup(KindID);
1272 void Instruction::getAllMetadataImpl(
1273 SmallVectorImpl<std::pair<unsigned, MDNode *>> &Result) const {
1276 // Handle 'dbg' as a special case since it is not stored in the hash table.
1279 std::make_pair((unsigned)LLVMContext::MD_dbg, DbgLoc.getAsMDNode()));
1280 if (!hasMetadataHashEntry())
1284 assert(hasMetadataHashEntry() &&
1285 getContext().pImpl->InstructionMetadata.count(this) &&
1286 "Shouldn't have called this");
1287 const auto &Info = getContext().pImpl->InstructionMetadata.find(this)->second;
1288 assert(!Info.empty() && "Shouldn't have called this");
1289 Info.getAll(Result);
1292 void Instruction::getAllMetadataOtherThanDebugLocImpl(
1293 SmallVectorImpl<std::pair<unsigned, MDNode *>> &Result) const {
1295 assert(hasMetadataHashEntry() &&
1296 getContext().pImpl->InstructionMetadata.count(this) &&
1297 "Shouldn't have called this");
1298 const auto &Info = getContext().pImpl->InstructionMetadata.find(this)->second;
1299 assert(!Info.empty() && "Shouldn't have called this");
1300 Info.getAll(Result);
1303 bool Instruction::extractProfMetadata(uint64_t &TrueVal,
1304 uint64_t &FalseVal) const {
1306 (getOpcode() == Instruction::Br || getOpcode() == Instruction::Select) &&
1307 "Looking for branch weights on something besides branch or select");
1309 auto *ProfileData = getMetadata(LLVMContext::MD_prof);
1310 if (!ProfileData || ProfileData->getNumOperands() != 3)
1313 auto *ProfDataName = dyn_cast<MDString>(ProfileData->getOperand(0));
1314 if (!ProfDataName || !ProfDataName->getString().equals("branch_weights"))
1317 auto *CITrue = mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(1));
1318 auto *CIFalse = mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(2));
1319 if (!CITrue || !CIFalse)
1322 TrueVal = CITrue->getValue().getZExtValue();
1323 FalseVal = CIFalse->getValue().getZExtValue();
1328 bool Instruction::extractProfTotalWeight(uint64_t &TotalVal) const {
1329 assert((getOpcode() == Instruction::Br ||
1330 getOpcode() == Instruction::Select ||
1331 getOpcode() == Instruction::Call ||
1332 getOpcode() == Instruction::Invoke ||
1333 getOpcode() == Instruction::Switch) &&
1334 "Looking for branch weights on something besides branch");
1337 auto *ProfileData = getMetadata(LLVMContext::MD_prof);
1341 auto *ProfDataName = dyn_cast<MDString>(ProfileData->getOperand(0));
1345 if (ProfDataName->getString().equals("branch_weights")) {
1347 for (unsigned i = 1; i < ProfileData->getNumOperands(); i++) {
1348 auto *V = mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(i));
1351 TotalVal += V->getValue().getZExtValue();
1354 } else if (ProfDataName->getString().equals("VP") &&
1355 ProfileData->getNumOperands() > 3) {
1356 TotalVal = mdconst::dyn_extract<ConstantInt>(ProfileData->getOperand(2))
1364 void Instruction::clearMetadataHashEntries() {
1365 assert(hasMetadataHashEntry() && "Caller should check");
1366 getContext().pImpl->InstructionMetadata.erase(this);
1367 setHasMetadataHashEntry(false);
1370 void GlobalObject::getMetadata(unsigned KindID,
1371 SmallVectorImpl<MDNode *> &MDs) const {
1373 getContext().pImpl->GlobalObjectMetadata[this].get(KindID, MDs);
1376 void GlobalObject::getMetadata(StringRef Kind,
1377 SmallVectorImpl<MDNode *> &MDs) const {
1379 getMetadata(getContext().getMDKindID(Kind), MDs);
1382 void GlobalObject::addMetadata(unsigned KindID, MDNode &MD) {
1384 setHasMetadataHashEntry(true);
1386 getContext().pImpl->GlobalObjectMetadata[this].insert(KindID, MD);
1389 void GlobalObject::addMetadata(StringRef Kind, MDNode &MD) {
1390 addMetadata(getContext().getMDKindID(Kind), MD);
1393 void GlobalObject::eraseMetadata(unsigned KindID) {
1394 // Nothing to unset.
1398 auto &Store = getContext().pImpl->GlobalObjectMetadata[this];
1399 Store.erase(KindID);
1404 void GlobalObject::getAllMetadata(
1405 SmallVectorImpl<std::pair<unsigned, MDNode *>> &MDs) const {
1411 getContext().pImpl->GlobalObjectMetadata[this].getAll(MDs);
1414 void GlobalObject::clearMetadata() {
1417 getContext().pImpl->GlobalObjectMetadata.erase(this);
1418 setHasMetadataHashEntry(false);
1421 void GlobalObject::setMetadata(unsigned KindID, MDNode *N) {
1422 eraseMetadata(KindID);
1424 addMetadata(KindID, *N);
1427 void GlobalObject::setMetadata(StringRef Kind, MDNode *N) {
1428 setMetadata(getContext().getMDKindID(Kind), N);
1431 MDNode *GlobalObject::getMetadata(unsigned KindID) const {
1432 SmallVector<MDNode *, 1> MDs;
1433 getMetadata(KindID, MDs);
1434 assert(MDs.size() <= 1 && "Expected at most one metadata attachment");
1440 MDNode *GlobalObject::getMetadata(StringRef Kind) const {
1441 return getMetadata(getContext().getMDKindID(Kind));
1444 void GlobalObject::copyMetadata(const GlobalObject *Other, unsigned Offset) {
1445 SmallVector<std::pair<unsigned, MDNode *>, 8> MDs;
1446 Other->getAllMetadata(MDs);
1447 for (auto &MD : MDs) {
1448 // We need to adjust the type metadata offset.
1449 if (Offset != 0 && MD.first == LLVMContext::MD_type) {
1450 auto *OffsetConst = cast<ConstantInt>(
1451 cast<ConstantAsMetadata>(MD.second->getOperand(0))->getValue());
1452 Metadata *TypeId = MD.second->getOperand(1);
1453 auto *NewOffsetMD = ConstantAsMetadata::get(ConstantInt::get(
1454 OffsetConst->getType(), OffsetConst->getValue() + Offset));
1455 addMetadata(LLVMContext::MD_type,
1456 *MDNode::get(getContext(), {NewOffsetMD, TypeId}));
1459 // If an offset adjustment was specified we need to modify the DIExpression
1460 // to prepend the adjustment:
1461 // !DIExpression(DW_OP_plus, Offset, [original expr])
1462 auto *Attachment = MD.second;
1463 if (Offset != 0 && MD.first == LLVMContext::MD_dbg) {
1464 DIGlobalVariable *GV = dyn_cast<DIGlobalVariable>(Attachment);
1465 DIExpression *E = nullptr;
1467 auto *GVE = cast<DIGlobalVariableExpression>(Attachment);
1468 GV = GVE->getVariable();
1469 E = GVE->getExpression();
1471 ArrayRef<uint64_t> OrigElements;
1473 OrigElements = E->getElements();
1474 std::vector<uint64_t> Elements(OrigElements.size() + 2);
1475 Elements[0] = dwarf::DW_OP_plus_uconst;
1476 Elements[1] = Offset;
1477 std::copy(OrigElements.begin(), OrigElements.end(), Elements.begin() + 2);
1478 E = DIExpression::get(getContext(), Elements);
1479 Attachment = DIGlobalVariableExpression::get(getContext(), GV, E);
1481 addMetadata(MD.first, *Attachment);
1485 void GlobalObject::addTypeMetadata(unsigned Offset, Metadata *TypeID) {
1487 LLVMContext::MD_type,
1488 *MDTuple::get(getContext(),
1489 {ConstantAsMetadata::get(ConstantInt::get(
1490 Type::getInt64Ty(getContext()), Offset)),
1494 void Function::setSubprogram(DISubprogram *SP) {
1495 setMetadata(LLVMContext::MD_dbg, SP);
1498 DISubprogram *Function::getSubprogram() const {
1499 return cast_or_null<DISubprogram>(getMetadata(LLVMContext::MD_dbg));
1502 bool Function::isDebugInfoForProfiling() const {
1503 if (DISubprogram *SP = getSubprogram()) {
1504 if (DICompileUnit *CU = SP->getUnit()) {
1505 return CU->getDebugInfoForProfiling();
1511 void GlobalVariable::addDebugInfo(DIGlobalVariableExpression *GV) {
1512 addMetadata(LLVMContext::MD_dbg, *GV);
1515 void GlobalVariable::getDebugInfo(
1516 SmallVectorImpl<DIGlobalVariableExpression *> &GVs) const {
1517 SmallVector<MDNode *, 1> MDs;
1518 getMetadata(LLVMContext::MD_dbg, MDs);
1519 for (MDNode *MD : MDs)
1520 GVs.push_back(cast<DIGlobalVariableExpression>(MD));