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
26namespace llvm {
27
28class BasicBlock;
29class Comdat;
30class DIArgList;
31class Function;
32class Instruction;
33class LocalAsMetadata;
34class MDNode;
35class Metadata;
36class Module;
37class NamedMDNode;
38class raw_ostream;
39class Type;
40class Value;
41class ValueSymbolTable;
42
43class ValueEnumerator {
44public:
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
56private:
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
140public:
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
239private:
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
306