lib/VMCore/Metadata.cpp

   1 //===-- Metadata.cpp - Implement Metadata classes -------------------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file implements the Metadata classes.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Metadata.h"
  15 #include "LLVMContextImpl.h"
  16 #include "llvm/LLVMContext.h"
  17 #include "llvm/Module.h"
  18 #include "llvm/Instruction.h"
  19 #include "llvm/ADT/DenseMap.h"
  20 #include "llvm/ADT/StringMap.h"
  21 #include "llvm/ADT/SmallString.h"
  22 #include "llvm/ADT/STLExtras.h"
  23 #include "SymbolTableListTraitsImpl.h"
  24 #include "llvm/Support/LeakDetector.h"
  25 #include "llvm/Support/ValueHandle.h"
  26 using namespace llvm;
  27
  28 //===----------------------------------------------------------------------===//
  29 // MDString implementation.
  30 //
  31
  32 MDString::MDString(LLVMContext &C, StringRef S)
  33   : Value(Type::getMetadataTy(C), Value::MDStringVal), Str(S) {}
  34
  35 MDString *MDString::get(LLVMContext &Context, StringRef Str) {
  36   LLVMContextImpl *pImpl = Context.pImpl;
  37   StringMapEntry<MDString *> &Entry =
  38     pImpl->MDStringCache.GetOrCreateValue(Str);
  39   MDString *&S = Entry.getValue();
  40   if (!S) S = new MDString(Context, Entry.getKey());
  41   return S;
  42 }
  43
  44 //===----------------------------------------------------------------------===//
  45 // MDNodeOperand implementation.
  46 //
  47
  48 // Use CallbackVH to hold MDNode operands.
  49 namespace llvm {
  50 class MDNodeOperand : public CallbackVH {
  51   MDNode *Parent;
  52 public:
  53   MDNodeOperand(Value *V, MDNode *P) : CallbackVH(V), Parent(P) {}
  54   ~MDNodeOperand() {}
  55
  56   void set(Value *V) {
  57     setValPtr(V);
  58   }
  59
  60   virtual void deleted();
  61   virtual void allUsesReplacedWith(Value *NV);
  62 };
  63 } // end namespace llvm.
  64
  65
  66 void MDNodeOperand::deleted() {
  67   Parent->replaceOperand(this, 0);
  68 }
  69
  70 void MDNodeOperand::allUsesReplacedWith(Value *NV) {
  71   Parent->replaceOperand(this, NV);
  72 }
  73
  74
  75
  76 //===----------------------------------------------------------------------===//
  77 // MDNode implementation.
  78 //
  79
  80 /// getOperandPtr - Helper function to get the MDNodeOperand's coallocated on
  81 /// the end of the MDNode.
  82 static MDNodeOperand *getOperandPtr(MDNode *N, unsigned Op) {
  83   // Use <= instead of < to permit a one-past-the-end address.
  84   assert(Op <= N->getNumOperands() && "Invalid operand number");
  85   return reinterpret_cast<MDNodeOperand*>(N+1)+Op;
  86 }
  87
  88 MDNode::MDNode(LLVMContext &C, ArrayRef<Value*> Vals, bool isFunctionLocal)
  89 : Value(Type::getMetadataTy(C), Value::MDNodeVal) {
  90   NumOperands = Vals.size();
  91
  92   if (isFunctionLocal)
  93     setValueSubclassData(getSubclassDataFromValue() | FunctionLocalBit);
  94
  95   // Initialize the operand list, which is co-allocated on the end of the node.
  96   unsigned i = 0;
  97   for (MDNodeOperand *Op = getOperandPtr(this, 0), *E = Op+NumOperands;
  98        Op != E; ++Op, ++i)
  99     new (Op) MDNodeOperand(Vals[i], this);
 100 }
 101
 102
 103 /// ~MDNode - Destroy MDNode.
 104 MDNode::~MDNode() {
 105   assert((getSubclassDataFromValue() & DestroyFlag) != 0 &&
 106          "Not being destroyed through destroy()?");
 107   LLVMContextImpl *pImpl = getType()->getContext().pImpl;
 108   if (isNotUniqued()) {
 109     pImpl->NonUniquedMDNodes.erase(this);
 110   } else {
 111     pImpl->MDNodeSet.RemoveNode(this);
 112   }
 113
 114   // Destroy the operands.
 115   for (MDNodeOperand *Op = getOperandPtr(this, 0), *E = Op+NumOperands;
 116        Op != E; ++Op)
 117     Op->~MDNodeOperand();
 118 }
 119
 120 static const Function *getFunctionForValue(Value *V) {
 121   if (!V) return NULL;
 122   if (Instruction *I = dyn_cast<Instruction>(V)) {
 123     BasicBlock *BB = I->getParent();
 124     return BB ? BB->getParent() : 0;
 125   }
 126   if (Argument *A = dyn_cast<Argument>(V))
 127     return A->getParent();
 128   if (BasicBlock *BB = dyn_cast<BasicBlock>(V))
 129     return BB->getParent();
 130   if (MDNode *MD = dyn_cast<MDNode>(V))
 131     return MD->getFunction();
 132   return NULL;
 133 }
 134
 135 #ifndef NDEBUG
 136 static const Function *assertLocalFunction(const MDNode *N) {
 137   if (!N->isFunctionLocal()) return 0;
 138
 139   // FIXME: This does not handle cyclic function local metadata.
 140   const Function *F = 0, *NewF = 0;
 141   for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) {
 142     if (Value *V = N->getOperand(i)) {
 143       if (MDNode *MD = dyn_cast<MDNode>(V))
 144         NewF = assertLocalFunction(MD);
 145       else
 146         NewF = getFunctionForValue(V);
 147     }
 148     if (F == 0)
 149       F = NewF;
 150     else
 151       assert((NewF == 0 || F == NewF) &&"inconsistent function-local metadata");
 152   }
 153   return F;
 154 }
 155 #endif
 156
 157 // getFunction - If this metadata is function-local and recursively has a
 158 // function-local operand, return the first such operand's parent function.
 159 // Otherwise, return null. getFunction() should not be used for performance-
 160 // critical code because it recursively visits all the MDNode's operands.
 161 const Function *MDNode::getFunction() const {
 162 #ifndef NDEBUG
 163   return assertLocalFunction(this);
 164 #endif
 165   if (!isFunctionLocal()) return NULL;
 166   for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
 167     if (const Function *F = getFunctionForValue(getOperand(i)))
 168       return F;
 169   return NULL;
 170 }
 171
 172 // destroy - Delete this node.  Only when there are no uses.
 173 void MDNode::destroy() {
 174   setValueSubclassData(getSubclassDataFromValue() | DestroyFlag);
 175   // Placement delete, the free the memory.
 176   this->~MDNode();
 177   free(this);
 178 }
 179
 180 /// isFunctionLocalValue - Return true if this is a value that would require a
 181 /// function-local MDNode.
 182 static bool isFunctionLocalValue(Value *V) {
 183   return isa<Instruction>(V) || isa<Argument>(V) || isa<BasicBlock>(V) ||
 184          (isa<MDNode>(V) && cast<MDNode>(V)->isFunctionLocal());
 185 }
 186
 187 MDNode *MDNode::getMDNode(LLVMContext &Context, ArrayRef<Value*> Vals,
 188                           FunctionLocalness FL, bool Insert) {
 189   LLVMContextImpl *pImpl = Context.pImpl;
 190
 191   // Add all the operand pointers. Note that we don't have to add the
 192   // isFunctionLocal bit because that's implied by the operands.
 193   // Note that if the operands are later nulled out, the node will be
 194   // removed from the uniquing map.
 195   FoldingSetNodeID ID;
 196   for (unsigned i = 0; i != Vals.size(); ++i)
 197     ID.AddPointer(Vals[i]);
 198
 199   void *InsertPoint;
 200   MDNode *N = NULL;
 201
 202   if ((N = pImpl->MDNodeSet.FindNodeOrInsertPos(ID, InsertPoint)))
 203     return N;
 204
 205   bool isFunctionLocal = false;
 206   switch (FL) {
 207   case FL_Unknown:
 208     for (unsigned i = 0; i != Vals.size(); ++i) {
 209       Value *V = Vals[i];
 210       if (!V) continue;
 211       if (isFunctionLocalValue(V)) {
 212         isFunctionLocal = true;
 213         break;
 214       }
 215     }
 216     break;
 217   case FL_No:
 218     isFunctionLocal = false;
 219     break;
 220   case FL_Yes:
 221     isFunctionLocal = true;
 222     break;
 223   }
 224
 225   // Coallocate space for the node and Operands together, then placement new.
 226   void *Ptr = malloc(sizeof(MDNode)+Vals.size()*sizeof(MDNodeOperand));
 227   N = new (Ptr) MDNode(Context, Vals, isFunctionLocal);
 228
 229   // InsertPoint will have been set by the FindNodeOrInsertPos call.
 230   pImpl->MDNodeSet.InsertNode(N, InsertPoint);
 231
 232   return N;
 233 }
 234
 235 MDNode *MDNode::get(LLVMContext &Context, ArrayRef<Value*> Vals) {
 236   return getMDNode(Context, Vals, FL_Unknown);
 237 }
 238
 239 MDNode *MDNode::getWhenValsUnresolved(LLVMContext &Context,
 240                                       ArrayRef<Value*> Vals,
 241                                       bool isFunctionLocal) {
 242   return getMDNode(Context, Vals, isFunctionLocal ? FL_Yes : FL_No);
 243 }
 244
 245 MDNode *MDNode::getIfExists(LLVMContext &Context, ArrayRef<Value*> Vals) {
 246   return getMDNode(Context, Vals, FL_Unknown, false);
 247 }
 248
 249 MDNode *MDNode::getTemporary(LLVMContext &Context, ArrayRef<Value*> Vals) {
 250   MDNode *N =
 251     (MDNode *)malloc(sizeof(MDNode)+Vals.size()*sizeof(MDNodeOperand));
 252   N = new (N) MDNode(Context, Vals, FL_No);
 253   N->setValueSubclassData(N->getSubclassDataFromValue() |
 254                           NotUniquedBit);
 255   LeakDetector::addGarbageObject(N);
 256   return N;
 257 }
 258
 259 void MDNode::deleteTemporary(MDNode *N) {
 260   assert(N->use_empty() && "Temporary MDNode has uses!");
 261   assert(!N->getContext().pImpl->MDNodeSet.RemoveNode(N) &&
 262          "Deleting a non-temporary uniqued node!");
 263   assert(!N->getContext().pImpl->NonUniquedMDNodes.erase(N) &&
 264          "Deleting a non-temporary non-uniqued node!");
 265   assert((N->getSubclassDataFromValue() & NotUniquedBit) &&
 266          "Temporary MDNode does not have NotUniquedBit set!");
 267   assert((N->getSubclassDataFromValue() & DestroyFlag) == 0 &&
 268          "Temporary MDNode has DestroyFlag set!");
 269   LeakDetector::removeGarbageObject(N);
 270   N->destroy();
 271 }
 272
 273 /// getOperand - Return specified operand.
 274 Value *MDNode::getOperand(unsigned i) const {
 275   return *getOperandPtr(const_cast<MDNode*>(this), i);
 276 }
 277
 278 void MDNode::Profile(FoldingSetNodeID &ID) const {
 279   // Add all the operand pointers. Note that we don't have to add the
 280   // isFunctionLocal bit because that's implied by the operands.
 281   // Note that if the operands are later nulled out, the node will be
 282   // removed from the uniquing map.
 283   for (unsigned i = 0, e = getNumOperands(); i != e; ++i)
 284     ID.AddPointer(getOperand(i));
 285 }
 286
 287 void MDNode::setIsNotUniqued() {
 288   setValueSubclassData(getSubclassDataFromValue() | NotUniquedBit);
 289   LLVMContextImpl *pImpl = getType()->getContext().pImpl;
 290   pImpl->NonUniquedMDNodes.insert(this);
 291 }
 292
 293 // Replace value from this node's operand list.
 294 void MDNode::replaceOperand(MDNodeOperand *Op, Value *To) {
 295   Value *From = *Op;
 296
 297   // If is possible that someone did GV->RAUW(inst), replacing a global variable
 298   // with an instruction or some other function-local object.  If this is a
 299   // non-function-local MDNode, it can't point to a function-local object.
 300   // Handle this case by implicitly dropping the MDNode reference to null.
 301   // Likewise if the MDNode is function-local but for a different function.
 302   if (To && isFunctionLocalValue(To)) {
 303     if (!isFunctionLocal())
 304       To = 0;
 305     else {
 306       const Function *F = getFunction();
 307       const Function *FV = getFunctionForValue(To);
 308       // Metadata can be function-local without having an associated function.
 309       // So only consider functions to have changed if non-null.
 310       if (F && FV && F != FV)
 311         To = 0;
 312     }
 313   }
 314
 315   if (From == To)
 316     return;
 317
 318   // Update the operand.
 319   Op->set(To);
 320
 321   // If this node is already not being uniqued (because one of the operands
 322   // already went to null), then there is nothing else to do here.
 323   if (isNotUniqued()) return;
 324
 325   LLVMContextImpl *pImpl = getType()->getContext().pImpl;
 326
 327   // Remove "this" from the context map.  FoldingSet doesn't have to reprofile
 328   // this node to remove it, so we don't care what state the operands are in.
 329   pImpl->MDNodeSet.RemoveNode(this);
 330
 331   // If we are dropping an argument to null, we choose to not unique the MDNode
 332   // anymore.  This commonly occurs during destruction, and uniquing these
 333   // brings little reuse.  Also, this means we don't need to include
 334   // isFunctionLocal bits in FoldingSetNodeIDs for MDNodes.
 335   if (To == 0) {
 336     setIsNotUniqued();
 337     return;
 338   }
 339
 340   // Now that the node is out of the folding set, get ready to reinsert it.
 341   // First, check to see if another node with the same operands already exists
 342   // in the set.  If so, then this node is redundant.
 343   FoldingSetNodeID ID;
 344   Profile(ID);
 345   void *InsertPoint;
 346   if (MDNode *N = pImpl->MDNodeSet.FindNodeOrInsertPos(ID, InsertPoint)) {
 347     replaceAllUsesWith(N);
 348     destroy();
 349     return;
 350   }
 351
 352   // InsertPoint will have been set by the FindNodeOrInsertPos call.
 353   pImpl->MDNodeSet.InsertNode(this, InsertPoint);
 354
 355   // If this MDValue was previously function-local but no longer is, clear
 356   // its function-local flag.
 357   if (isFunctionLocal() && !isFunctionLocalValue(To)) {
 358     bool isStillFunctionLocal = false;
 359     for (unsigned i = 0, e = getNumOperands(); i != e; ++i) {
 360       Value *V = getOperand(i);
 361       if (!V) continue;
 362       if (isFunctionLocalValue(V)) {
 363         isStillFunctionLocal = true;
 364         break;
 365       }
 366     }
 367     if (!isStillFunctionLocal)
 368       setValueSubclassData(getSubclassDataFromValue() & ~FunctionLocalBit);
 369   }
 370 }
 371
 372 //===----------------------------------------------------------------------===//
 373 // NamedMDNode implementation.
 374 //
 375
 376 static SmallVector<TrackingVH<MDNode>, 4> &getNMDOps(void *Operands) {
 377   return *(SmallVector<TrackingVH<MDNode>, 4>*)Operands;
 378 }
 379
 380 NamedMDNode::NamedMDNode(const Twine &N)
 381   : Name(N.str()), Parent(0),
 382     Operands(new SmallVector<TrackingVH<MDNode>, 4>()) {
 383 }
 384
 385 NamedMDNode::~NamedMDNode() {
 386   dropAllReferences();
 387   delete &getNMDOps(Operands);
 388 }
 389
 390 /// getNumOperands - Return number of NamedMDNode operands.
 391 unsigned NamedMDNode::getNumOperands() const {
 392   return (unsigned)getNMDOps(Operands).size();
 393 }
 394
 395 /// getOperand - Return specified operand.
 396 MDNode *NamedMDNode::getOperand(unsigned i) const {
 397   assert(i < getNumOperands() && "Invalid Operand number!");
 398   return dyn_cast<MDNode>(&*getNMDOps(Operands)[i]);
 399 }
 400
 401 /// addOperand - Add metadata Operand.
 402 void NamedMDNode::addOperand(MDNode *M) {
 403   assert(!M->isFunctionLocal() &&
 404          "NamedMDNode operands must not be function-local!");
 405   getNMDOps(Operands).push_back(TrackingVH<MDNode>(M));
 406 }
 407
 408 /// eraseFromParent - Drop all references and remove the node from parent
 409 /// module.
 410 void NamedMDNode::eraseFromParent() {
 411   getParent()->eraseNamedMetadata(this);
 412 }
 413
 414 /// dropAllReferences - Remove all uses and clear node vector.
 415 void NamedMDNode::dropAllReferences() {
 416   getNMDOps(Operands).clear();
 417 }
 418
 419 /// getName - Return a constant reference to this named metadata's name.
 420 StringRef NamedMDNode::getName() const {
 421   return StringRef(Name);
 422 }
 423
 424 //===----------------------------------------------------------------------===//
 425 // Instruction Metadata method implementations.
 426 //
 427
 428 void Instruction::setMetadata(const char *Kind, MDNode *Node) {
 429   if (Node == 0 && !hasMetadata()) return;
 430   setMetadata(getContext().getMDKindID(Kind), Node);
 431 }
 432
 433 MDNode *Instruction::getMetadataImpl(const char *Kind) const {
 434   return getMetadataImpl(getContext().getMDKindID(Kind));
 435 }
 436
 437 /// setMetadata - Set the metadata of of the specified kind to the specified
 438 /// node.  This updates/replaces metadata if already present, or removes it if
 439 /// Node is null.
 440 void Instruction::setMetadata(unsigned KindID, MDNode *Node) {
 441   if (Node == 0 && !hasMetadata()) return;
 442
 443   // Handle 'dbg' as a special case since it is not stored in the hash table.
 444   if (KindID == LLVMContext::MD_dbg) {
 445     DbgLoc = DebugLoc::getFromDILocation(Node);
 446     return;
 447   }
 448
 449   // Handle the case when we're adding/updating metadata on an instruction.
 450   if (Node) {
 451     LLVMContextImpl::MDMapTy &Info = getContext().pImpl->MetadataStore[this];
 452     assert(!Info.empty() == hasMetadataHashEntry() &&
 453            "HasMetadata bit is wonked");
 454     if (Info.empty()) {
 455       setHasMetadataHashEntry(true);
 456     } else {
 457       // Handle replacement of an existing value.
 458       for (unsigned i = 0, e = Info.size(); i != e; ++i)
 459         if (Info[i].first == KindID) {
 460           Info[i].second = Node;
 461           return;
 462         }
 463     }
 464
 465     // No replacement, just add it to the list.
 466     Info.push_back(std::make_pair(KindID, Node));
 467     return;
 468   }
 469
 470   // Otherwise, we're removing metadata from an instruction.
 471   assert(hasMetadataHashEntry() &&
 472          getContext().pImpl->MetadataStore.count(this) &&
 473          "HasMetadata bit out of date!");
 474   LLVMContextImpl::MDMapTy &Info = getContext().pImpl->MetadataStore[this];
 475
 476   // Common case is removing the only entry.
 477   if (Info.size() == 1 && Info[0].first == KindID) {
 478     getContext().pImpl->MetadataStore.erase(this);
 479     setHasMetadataHashEntry(false);
 480     return;
 481   }
 482
 483   // Handle removal of an existing value.
 484   for (unsigned i = 0, e = Info.size(); i != e; ++i)
 485     if (Info[i].first == KindID) {
 486       Info[i] = Info.back();
 487       Info.pop_back();
 488       assert(!Info.empty() && "Removing last entry should be handled above");
 489       return;
 490     }
 491   // Otherwise, removing an entry that doesn't exist on the instruction.
 492 }
 493
 494 MDNode *Instruction::getMetadataImpl(unsigned KindID) const {
 495   // Handle 'dbg' as a special case since it is not stored in the hash table.
 496   if (KindID == LLVMContext::MD_dbg)
 497     return DbgLoc.getAsMDNode(getContext());
 498
 499   if (!hasMetadataHashEntry()) return 0;
 500
 501   LLVMContextImpl::MDMapTy &Info = getContext().pImpl->MetadataStore[this];
 502   assert(!Info.empty() && "bit out of sync with hash table");
 503
 504   for (LLVMContextImpl::MDMapTy::iterator I = Info.begin(), E = Info.end();
 505        I != E; ++I)
 506     if (I->first == KindID)
 507       return I->second;
 508   return 0;
 509 }
 510
 511 void Instruction::getAllMetadataImpl(SmallVectorImpl<std::pair<unsigned,
 512                                        MDNode*> > &Result) const {
 513   Result.clear();
 514
 515   // Handle 'dbg' as a special case since it is not stored in the hash table.
 516   if (!DbgLoc.isUnknown()) {
 517     Result.push_back(std::make_pair((unsigned)LLVMContext::MD_dbg,
 518                                     DbgLoc.getAsMDNode(getContext())));
 519     if (!hasMetadataHashEntry()) return;
 520   }
 521
 522   assert(hasMetadataHashEntry() &&
 523          getContext().pImpl->MetadataStore.count(this) &&
 524          "Shouldn't have called this");
 525   const LLVMContextImpl::MDMapTy &Info =
 526     getContext().pImpl->MetadataStore.find(this)->second;
 527   assert(!Info.empty() && "Shouldn't have called this");
 528
 529   Result.append(Info.begin(), Info.end());
 530
 531   // Sort the resulting array so it is stable.
 532   if (Result.size() > 1)
 533     array_pod_sort(Result.begin(), Result.end());
 534 }
 535
 536 void Instruction::
 537 getAllMetadataOtherThanDebugLocImpl(SmallVectorImpl<std::pair<unsigned,
 538                                     MDNode*> > &Result) const {
 539   Result.clear();
 540   assert(hasMetadataHashEntry() &&
 541          getContext().pImpl->MetadataStore.count(this) &&
 542          "Shouldn't have called this");
 543   const LLVMContextImpl::MDMapTy &Info =
 544   getContext().pImpl->MetadataStore.find(this)->second;
 545   assert(!Info.empty() && "Shouldn't have called this");
 546
 547   Result.append(Info.begin(), Info.end());
 548
 549   // Sort the resulting array so it is stable.
 550   if (Result.size() > 1)
 551     array_pod_sort(Result.begin(), Result.end());
 552 }
 553
 554
 555 /// clearMetadataHashEntries - Clear all hashtable-based metadata from
 556 /// this instruction.
 557 void Instruction::clearMetadataHashEntries() {
 558   assert(hasMetadataHashEntry() && "Caller should check");
 559   getContext().pImpl->MetadataStore.erase(this);
 560   setHasMetadataHashEntry(false);
 561 }
 562