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(Val: 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(Val: 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(Val: 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(Val: 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(N: NumModuleMDs, M: NumMDStrings);
205 }
206
207 /// Get the non-MDString metadata for this block.
208 ArrayRef<const Metadata *> getNonMDStrings() const {
209 return ArrayRef(MDs).slice(N: NumModuleMDs).slice(N: 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 computeBitsRequiredForTypeIndices() 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