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