llvm/lib/Bitcode/Writer/ValueEnumerator.h

   1 //===- Bitcode/Writer/ValueEnumerator.h - Number values ---------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This class gives values and types Unique ID's.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #ifndef LLVM_LIB_BITCODE_WRITER_VALUEENUMERATOR_H
  14 #define LLVM_LIB_BITCODE_WRITER_VALUEENUMERATOR_H
  15
  16 #include "llvm/ADT/ArrayRef.h"
  17 #include "llvm/ADT/DenseMap.h"
  18 #include "llvm/ADT/UniqueVector.h"
  19 #include "llvm/IR/Attributes.h"
  20 #include "llvm/IR/UseListOrder.h"
  21 #include <cassert>
  22 #include <cstdint>
  23 #include <utility>
  24 #include <vector>
  25
  26 namespace llvm {
  27
  28 class BasicBlock;
  29 class Comdat;
  30 class DIArgList;
  31 class Function;
  32 class Instruction;
  33 class LocalAsMetadata;
  34 class MDNode;
  35 class Metadata;
  36 class Module;
  37 class NamedMDNode;
  38 class raw_ostream;
  39 class Type;
  40 class Value;
  41 class ValueSymbolTable;
  42
  43 class ValueEnumerator {
  44 public:
  45   using TypeList = std::vector<Type *>;
  46
  47   // For each value, we remember its Value* and occurrence frequency.
  48   using ValueList = std::vector<std::pair<const Value *, unsigned>>;
  49
  50   /// Attribute groups as encoded in bitcode are almost AttributeSets, but they
  51   /// include the AttributeList index, so we have to track that in our map.
  52   using IndexAndAttrSet = std::pair<unsigned, AttributeSet>;
  53
  54   UseListOrderStack UseListOrders;
  55
  56 private:
  57   using TypeMapType = DenseMap<Type *, unsigned>;
  58   TypeMapType TypeMap;
  59   TypeList Types;
  60
  61   using ValueMapType = DenseMap<const Value *, unsigned>;
  62   ValueMapType ValueMap;
  63   ValueList Values;
  64
  65   using ComdatSetType = UniqueVector<const Comdat *>;
  66   ComdatSetType Comdats;
  67
  68   std::vector<const Metadata *> MDs;
  69   std::vector<const Metadata *> FunctionMDs;
  70
  71   /// Index of information about a piece of metadata.
  72   struct MDIndex {
  73     unsigned F = 0;  ///< The ID of the function for this metadata, if any.
  74     unsigned ID = 0; ///< The implicit ID of this metadata in bitcode.
  75
  76     MDIndex() = default;
  77     explicit MDIndex(unsigned F) : F(F) {}
  78
  79     /// Check if this has a function tag, and it's different from NewF.
  80     bool hasDifferentFunction(unsigned NewF) const { return F && F != NewF; }
  81
  82     /// Fetch the MD this references out of the given metadata array.
  83     const Metadata *get(ArrayRef<const Metadata *> MDs) const {
  84       assert(ID && "Expected non-zero ID");
  85       assert(ID <= MDs.size() && "Expected valid ID");
  86       return MDs[ID - 1];
  87     }
  88   };
  89
  90   using MetadataMapType = DenseMap<const Metadata *, MDIndex>;
  91   MetadataMapType MetadataMap;
  92
  93   /// Range of metadata IDs, as a half-open range.
  94   struct MDRange {
  95     unsigned First = 0;
  96     unsigned Last = 0;
  97
  98     /// Number of strings in the prefix of the metadata range.
  99     unsigned NumStrings = 0;
 100
 101     MDRange() = default;
 102     explicit MDRange(unsigned First) : First(First) {}
 103   };
 104   SmallDenseMap<unsigned, MDRange, 1> FunctionMDInfo;
 105
 106   bool ShouldPreserveUseListOrder;
 107
 108   using AttributeGroupMapType = DenseMap<IndexAndAttrSet, unsigned>;
 109   AttributeGroupMapType AttributeGroupMap;
 110   std::vector<IndexAndAttrSet> AttributeGroups;
 111
 112   using AttributeListMapType = DenseMap<AttributeList, unsigned>;
 113   AttributeListMapType AttributeListMap;
 114   std::vector<AttributeList> AttributeLists;
 115
 116   /// GlobalBasicBlockIDs - This map memoizes the basic block ID's referenced by
 117   /// the "getGlobalBasicBlockID" method.
 118   mutable DenseMap<const BasicBlock*, unsigned> GlobalBasicBlockIDs;
 119
 120   using InstructionMapType = DenseMap<const Instruction *, unsigned>;
 121   InstructionMapType InstructionMap;
 122   unsigned InstructionCount;
 123
 124   /// BasicBlocks - This contains all the basic blocks for the currently
 125   /// incorporated function.  Their reverse mapping is stored in ValueMap.
 126   std::vector<const BasicBlock*> BasicBlocks;
 127
 128   /// When a function is incorporated, this is the size of the Values list
 129   /// before incorporation.
 130   unsigned NumModuleValues;
 131
 132   /// When a function is incorporated, this is the size of the Metadatas list
 133   /// before incorporation.
 134   unsigned NumModuleMDs = 0;
 135   unsigned NumMDStrings = 0;
 136
 137   unsigned FirstFuncConstantID;
 138   unsigned FirstInstID;
 139
 140 public:
 141   ValueEnumerator(const Module &M, bool ShouldPreserveUseListOrder);
 142   ValueEnumerator(const ValueEnumerator &) = delete;
 143   ValueEnumerator &operator=(const ValueEnumerator &) = delete;
 144
 145   void dump() const;
 146   void print(raw_ostream &OS, const ValueMapType &Map, const char *Name) const;
 147   void print(raw_ostream &OS, const MetadataMapType &Map,
 148              const char *Name) const;
 149
 150   unsigned getValueID(const Value *V) const;
 151
 152   unsigned getMetadataID(const Metadata *MD) const {
 153     auto ID = getMetadataOrNullID(MD);
 154     assert(ID != 0 && "Metadata not in slotcalculator!");
 155     return ID - 1;
 156   }
 157
 158   unsigned getMetadataOrNullID(const Metadata *MD) const {
 159     return MetadataMap.lookup(MD).ID;
 160   }
 161
 162   unsigned numMDs() const { return MDs.size(); }
 163
 164   bool shouldPreserveUseListOrder() const { return ShouldPreserveUseListOrder; }
 165
 166   unsigned getTypeID(Type *T) const {
 167     TypeMapType::const_iterator I = TypeMap.find(T);
 168     assert(I != TypeMap.end() && "Type not in ValueEnumerator!");
 169     return I->second-1;
 170   }
 171
 172   unsigned getInstructionID(const Instruction *I) const;
 173   void setInstructionID(const Instruction *I);
 174
 175   unsigned getAttributeListID(AttributeList PAL) const {
 176     if (PAL.isEmpty()) return 0;  // Null maps to zero.
 177     AttributeListMapType::const_iterator I = AttributeListMap.find(PAL);
 178     assert(I != AttributeListMap.end() && "Attribute not in ValueEnumerator!");
 179     return I->second;
 180   }
 181
 182   unsigned getAttributeGroupID(IndexAndAttrSet Group) const {
 183     if (!Group.second.hasAttributes())
 184       return 0; // Null maps to zero.
 185     AttributeGroupMapType::const_iterator I = AttributeGroupMap.find(Group);
 186     assert(I != AttributeGroupMap.end() && "Attribute not in ValueEnumerator!");
 187     return I->second;
 188   }
 189
 190   /// getFunctionConstantRange - Return the range of values that corresponds to
 191   /// function-local constants.
 192   void getFunctionConstantRange(unsigned &Start, unsigned &End) const {
 193     Start = FirstFuncConstantID;
 194     End = FirstInstID;
 195   }
 196
 197   const ValueList &getValues() const { return Values; }
 198
 199   /// Check whether the current block has any metadata to emit.
 200   bool hasMDs() const { return NumModuleMDs < MDs.size(); }
 201
 202   /// Get the MDString metadata for this block.
 203   ArrayRef<const Metadata *> getMDStrings() const {
 204     return ArrayRef(MDs).slice(NumModuleMDs, NumMDStrings);
 205   }
 206
 207   /// Get the non-MDString metadata for this block.
 208   ArrayRef<const Metadata *> getNonMDStrings() const {
 209     return ArrayRef(MDs).slice(NumModuleMDs).slice(NumMDStrings);
 210   }
 211
 212   const TypeList &getTypes() const { return Types; }
 213
 214   const std::vector<const BasicBlock*> &getBasicBlocks() const {
 215     return BasicBlocks;
 216   }
 217
 218   const std::vector<AttributeList> &getAttributeLists() const { return AttributeLists; }
 219
 220   const std::vector<IndexAndAttrSet> &getAttributeGroups() const {
 221     return AttributeGroups;
 222   }
 223
 224   const ComdatSetType &getComdats() const { return Comdats; }
 225   unsigned getComdatID(const Comdat *C) const;
 226
 227   /// getGlobalBasicBlockID - This returns the function-specific ID for the
 228   /// specified basic block.  This is relatively expensive information, so it
 229   /// should only be used by rare constructs such as address-of-label.
 230   unsigned getGlobalBasicBlockID(const BasicBlock *BB) const;
 231
 232   /// incorporateFunction/purgeFunction - If you'd like to deal with a function,
 233   /// use these two methods to get its data into the ValueEnumerator!
 234   void incorporateFunction(const Function &F);
 235
 236   void purgeFunction();
 237   uint64_t computeBitsRequiredForTypeIndicies() const;
 238
 239 private:
 240   void OptimizeConstants(unsigned CstStart, unsigned CstEnd);
 241
 242   /// Reorder the reachable metadata.
 243   ///
 244   /// This is not just an optimization, but is mandatory for emitting MDString
 245   /// correctly.
 246   void organizeMetadata();
 247
 248   /// Drop the function tag from the transitive operands of the given node.
 249   void dropFunctionFromMetadata(MetadataMapType::value_type &FirstMD);
 250
 251   /// Incorporate the function metadata.
 252   ///
 253   /// This should be called before enumerating LocalAsMetadata for the
 254   /// function.
 255   void incorporateFunctionMetadata(const Function &F);
 256
 257   /// Enumerate a single instance of metadata with the given function tag.
 258   ///
 259   /// If \c MD has already been enumerated, check that \c F matches its
 260   /// function tag.  If not, call \a dropFunctionFromMetadata().
 261   ///
 262   /// Otherwise, mark \c MD as visited.  Assign it an ID, or just return it if
 263   /// it's an \a MDNode.
 264   const MDNode *enumerateMetadataImpl(unsigned F, const Metadata *MD);
 265
 266   unsigned getMetadataFunctionID(const Function *F) const;
 267
 268   /// Enumerate reachable metadata in (almost) post-order.
 269   ///
 270   /// Enumerate all the metadata reachable from MD.  We want to minimize the
 271   /// cost of reading bitcode records, and so the primary consideration is that
 272   /// operands of uniqued nodes are resolved before the nodes are read.  This
 273   /// avoids re-uniquing them on the context and factors away RAUW support.
 274   ///
 275   /// This algorithm guarantees that subgraphs of uniqued nodes are in
 276   /// post-order.  Distinct subgraphs reachable only from a single uniqued node
 277   /// will be in post-order.
 278   ///
 279   /// \note The relative order of a distinct and uniqued node is irrelevant.
 280   /// \a organizeMetadata() will later partition distinct nodes ahead of
 281   /// uniqued ones.
 282   ///{
 283   void EnumerateMetadata(const Function *F, const Metadata *MD);
 284   void EnumerateMetadata(unsigned F, const Metadata *MD);
 285   ///}
 286
 287   void EnumerateFunctionLocalMetadata(const Function &F,
 288                                       const LocalAsMetadata *Local);
 289   void EnumerateFunctionLocalMetadata(unsigned F, const LocalAsMetadata *Local);
 290   void EnumerateFunctionLocalListMetadata(const Function &F,
 291                                           const DIArgList *ArgList);
 292   void EnumerateFunctionLocalListMetadata(unsigned F, const DIArgList *Arglist);
 293   void EnumerateNamedMDNode(const NamedMDNode *NMD);
 294   void EnumerateValue(const Value *V);
 295   void EnumerateType(Type *T);
 296   void EnumerateOperandType(const Value *V);
 297   void EnumerateAttributes(AttributeList PAL);
 298
 299   void EnumerateValueSymbolTable(const ValueSymbolTable &ST);
 300   void EnumerateNamedMetadata(const Module &M);
 301 };
 302
 303 } // end namespace llvm
 304
 305 #endif // LLVM_LIB_BITCODE_WRITER_VALUEENUMERATOR_H