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 "LLVMContextImpl.h"
  15 #include "llvm/Metadata.h"
  16 #include "llvm/LLVMContext.h"
  17 #include "llvm/Module.h"
  18 #include "SymbolTableListTraitsImpl.h"
  19 using namespace llvm;
  20
  21 //===----------------------------------------------------------------------===//
  22 //MetadataBase implementation
  23 //
  24
  25 /// resizeOperands - Metadata keeps track of other metadata uses using
  26 /// OperandList. Resize this list to hold anticipated number of metadata
  27 /// operands.
  28 void MetadataBase::resizeOperands(unsigned NumOps) {
  29   unsigned e = getNumOperands();
  30   if (NumOps == 0) {
  31     NumOps = e*2;
  32     if (NumOps < 2) NumOps = 2;
  33   } else if (NumOps > NumOperands) {
  34     // No resize needed.
  35     if (ReservedSpace >= NumOps) return;
  36   } else if (NumOps == NumOperands) {
  37     if (ReservedSpace == NumOps) return;
  38   } else {
  39     return;
  40   }
  41
  42   ReservedSpace = NumOps;
  43   Use *OldOps = OperandList;
  44   Use *NewOps = allocHungoffUses(NumOps);
  45   std::copy(OldOps, OldOps + e, NewOps);
  46   OperandList = NewOps;
  47   if (OldOps) Use::zap(OldOps, OldOps + e, true);
  48 }
  49 //===----------------------------------------------------------------------===//
  50 //MDString implementation
  51 //
  52 MDString *MDString::get(LLVMContext &Context, const StringRef &Str) {
  53   LLVMContextImpl *pImpl = Context.pImpl;
  54   sys::SmartScopedWriter<true> Writer(pImpl->ConstantsLock);
  55   StringMapEntry<MDString *> &Entry =
  56     pImpl->MDStringCache.GetOrCreateValue(Str);
  57   MDString *&S = Entry.getValue();
  58   if (!S) S = new MDString(Context, Entry.getKeyData(),
  59                            Entry.getKeyLength());
  60
  61   return S;
  62 }
  63
  64 //===----------------------------------------------------------------------===//
  65 //MDNode implementation
  66 //
  67 MDNode::MDNode(LLVMContext &C, Value*const* Vals, unsigned NumVals)
  68   : MetadataBase(Type::getMetadataTy(C), Value::MDNodeVal) {
  69   NumOperands = 0;
  70   resizeOperands(NumVals);
  71   for (unsigned i = 0; i != NumVals; ++i) {
  72     // Only record metadata uses.
  73     if (MetadataBase *MB = dyn_cast_or_null<MetadataBase>(Vals[i]))
  74       OperandList[NumOperands++] = MB;
  75     else if(Vals[i] &&
  76             Vals[i]->getType()->getTypeID() == Type::MetadataTyID)
  77       OperandList[NumOperands++] = Vals[i];
  78     Node.push_back(ElementVH(Vals[i], this));
  79   }
  80 }
  81
  82 void MDNode::Profile(FoldingSetNodeID &ID) const {
  83   for (const_elem_iterator I = elem_begin(), E = elem_end(); I != E; ++I)
  84     ID.AddPointer(*I);
  85 }
  86
  87 MDNode *MDNode::get(LLVMContext &Context, Value*const* Vals, unsigned NumVals) {
  88   LLVMContextImpl *pImpl = Context.pImpl;
  89   FoldingSetNodeID ID;
  90   for (unsigned i = 0; i != NumVals; ++i)
  91     ID.AddPointer(Vals[i]);
  92
  93   pImpl->ConstantsLock.reader_acquire();
  94   void *InsertPoint;
  95   MDNode *N = pImpl->MDNodeSet.FindNodeOrInsertPos(ID, InsertPoint);
  96   pImpl->ConstantsLock.reader_release();
  97
  98   if (!N) {
  99     sys::SmartScopedWriter<true> Writer(pImpl->ConstantsLock);
 100     N = pImpl->MDNodeSet.FindNodeOrInsertPos(ID, InsertPoint);
 101     if (!N) {
 102       // InsertPoint will have been set by the FindNodeOrInsertPos call.
 103       N = new MDNode(Context, Vals, NumVals);
 104       pImpl->MDNodeSet.InsertNode(N, InsertPoint);
 105     }
 106   }
 107
 108   return N;
 109 }
 110
 111 /// dropAllReferences - Remove all uses and clear node vector.
 112 void MDNode::dropAllReferences() {
 113   User::dropAllReferences();
 114   Node.clear();
 115 }
 116
 117 MDNode::~MDNode() {
 118   {
 119     LLVMContextImpl *pImpl = getType()->getContext().pImpl;
 120     sys::SmartScopedWriter<true> Writer(pImpl->ConstantsLock);
 121     pImpl->MDNodeSet.RemoveNode(this);
 122   }
 123   dropAllReferences();
 124 }
 125
 126 // Replace value from this node's element list.
 127 void MDNode::replaceElement(Value *From, Value *To) {
 128   if (From == To || !getType())
 129     return;
 130   LLVMContext &Context = getType()->getContext();
 131   LLVMContextImpl *pImpl = Context.pImpl;
 132
 133   // Find value. This is a linear search, do something if it consumes
 134   // lot of time. It is possible that to have multiple instances of
 135   // From in this MDNode's element list.
 136   SmallVector<unsigned, 4> Indexes;
 137   unsigned Index = 0;
 138   for (SmallVector<ElementVH, 4>::iterator I = Node.begin(),
 139          E = Node.end(); I != E; ++I, ++Index) {
 140     Value *V = *I;
 141     if (V && V == From)
 142       Indexes.push_back(Index);
 143   }
 144
 145   if (Indexes.empty())
 146     return;
 147
 148   // Remove "this" from the context map.
 149   {
 150     sys::SmartScopedWriter<true> Writer(pImpl->ConstantsLock);
 151     pImpl->MDNodeSet.RemoveNode(this);
 152   }
 153
 154   // MDNode only lists metadata elements in operand list, because MDNode
 155   // used by MDNode is considered a valid use. However on the side, MDNode
 156   // using a non-metadata value is not considered a "use" of non-metadata
 157   // value.
 158   SmallVector<unsigned, 4> OpIndexes;
 159   unsigned OpIndex = 0;
 160   for (User::op_iterator OI = op_begin(), OE = op_end();
 161        OI != OE; ++OI, OpIndex++) {
 162     if (*OI == From)
 163       OpIndexes.push_back(OpIndex);
 164   }
 165   if (MetadataBase *MDTo = dyn_cast_or_null<MetadataBase>(To)) {
 166     for (SmallVector<unsigned, 4>::iterator OI = OpIndexes.begin(),
 167            OE = OpIndexes.end(); OI != OE; ++OI)
 168       setOperand(*OI, MDTo);
 169   } else {
 170     for (SmallVector<unsigned, 4>::iterator OI = OpIndexes.begin(),
 171            OE = OpIndexes.end(); OI != OE; ++OI)
 172       setOperand(*OI, 0);
 173   }
 174
 175   // Replace From element(s) in place.
 176   for (SmallVector<unsigned, 4>::iterator I = Indexes.begin(), E = Indexes.end();
 177        I != E; ++I) {
 178     unsigned Index = *I;
 179     Node[Index] = ElementVH(To, this);
 180   }
 181
 182   // Insert updated "this" into the context's folding node set.
 183   // If a node with same element list already exist then before inserting
 184   // updated "this" into the folding node set, replace all uses of existing
 185   // node with updated "this" node.
 186   FoldingSetNodeID ID;
 187   Profile(ID);
 188   pImpl->ConstantsLock.reader_acquire();
 189   void *InsertPoint;
 190   MDNode *N = pImpl->MDNodeSet.FindNodeOrInsertPos(ID, InsertPoint);
 191   pImpl->ConstantsLock.reader_release();
 192
 193   if (N) {
 194     N->replaceAllUsesWith(this);
 195     delete N;
 196     N = 0;
 197   }
 198
 199   {
 200     sys::SmartScopedWriter<true> Writer(pImpl->ConstantsLock);
 201     N = pImpl->MDNodeSet.FindNodeOrInsertPos(ID, InsertPoint);
 202     if (!N) {
 203       // InsertPoint will have been set by the FindNodeOrInsertPos call.
 204       N = this;
 205       pImpl->MDNodeSet.InsertNode(N, InsertPoint);
 206     }
 207   }
 208 }
 209
 210 //===----------------------------------------------------------------------===//
 211 //NamedMDNode implementation
 212 //
 213 NamedMDNode::NamedMDNode(LLVMContext &C, const Twine &N,
 214                          MetadataBase*const* MDs,
 215                          unsigned NumMDs, Module *ParentModule)
 216   : MetadataBase(Type::getMetadataTy(C), Value::NamedMDNodeVal), Parent(0) {
 217   setName(N);
 218   NumOperands = 0;
 219   resizeOperands(NumMDs);
 220
 221   for (unsigned i = 0; i != NumMDs; ++i) {
 222     if (MDs[i])
 223       OperandList[NumOperands++] = MDs[i];
 224     Node.push_back(WeakMetadataVH(MDs[i]));
 225   }
 226   if (ParentModule)
 227     ParentModule->getNamedMDList().push_back(this);
 228 }
 229
 230 NamedMDNode *NamedMDNode::Create(const NamedMDNode *NMD, Module *M) {
 231   assert (NMD && "Invalid source NamedMDNode!");
 232   SmallVector<MetadataBase *, 4> Elems;
 233   for (unsigned i = 0, e = NMD->getNumElements(); i != e; ++i)
 234     Elems.push_back(NMD->getElement(i));
 235   return new NamedMDNode(NMD->getContext(), NMD->getName().data(),
 236                          Elems.data(), Elems.size(), M);
 237 }
 238
 239 /// eraseFromParent - Drop all references and remove the node from parent
 240 /// module.
 241 void NamedMDNode::eraseFromParent() {
 242   getParent()->getNamedMDList().erase(this);
 243 }
 244
 245 /// dropAllReferences - Remove all uses and clear node vector.
 246 void NamedMDNode::dropAllReferences() {
 247   User::dropAllReferences();
 248   Node.clear();
 249 }
 250
 251 NamedMDNode::~NamedMDNode() {
 252   dropAllReferences();
 253 }