1//===--- CodeGenTBAA.h - TBAA information for LLVM CodeGen ------*- 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 is the code that manages TBAA information and defines the TBAA policy
10// for the optimizer to use.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_CLANG_LIB_CODEGEN_CODEGENTBAA_H
15#define LLVM_CLANG_LIB_CODEGEN_CODEGENTBAA_H
16
17#include "clang/AST/Type.h"
18#include "clang/Basic/LLVM.h"
19#include "llvm/ADT/DenseMap.h"
20#include "llvm/IR/MDBuilder.h"
21#include "llvm/IR/Metadata.h"
22
23namespace clang {
24 class ASTContext;
25 class CodeGenOptions;
26 class LangOptions;
27 class MangleContext;
28 class QualType;
29 class Type;
30
31namespace CodeGen {
32class CGRecordLayout;
33
34// TBAAAccessKind - A kind of TBAA memory access descriptor.
35enum class TBAAAccessKind : unsigned {
36 Ordinary,
37 MayAlias,
38 Incomplete,
39};
40
41// TBAAAccessInfo - Describes a memory access in terms of TBAA.
42struct TBAAAccessInfo {
43 TBAAAccessInfo(TBAAAccessKind Kind, llvm::MDNode *BaseType,
44 llvm::MDNode *AccessType, uint64_t Offset, uint64_t Size)
45 : Kind(Kind), BaseType(BaseType), AccessType(AccessType),
46 Offset(Offset), Size(Size)
47 {}
48
49 TBAAAccessInfo(llvm::MDNode *BaseType, llvm::MDNode *AccessType,
50 uint64_t Offset, uint64_t Size)
51 : TBAAAccessInfo(TBAAAccessKind::Ordinary, BaseType, AccessType,
52 Offset, Size)
53 {}
54
55 explicit TBAAAccessInfo(llvm::MDNode *AccessType, uint64_t Size)
56 : TBAAAccessInfo(/* BaseType= */ nullptr, AccessType, /* Offset= */ 0, Size)
57 {}
58
59 TBAAAccessInfo()
60 : TBAAAccessInfo(/* AccessType= */ nullptr, /* Size= */ 0)
61 {}
62
63 static TBAAAccessInfo getMayAliasInfo() {
64 return TBAAAccessInfo(TBAAAccessKind::MayAlias,
65 /* BaseType= */ nullptr, /* AccessType= */ nullptr,
66 /* Offset= */ 0, /* Size= */ 0);
67 }
68
69 bool isMayAlias() const { return Kind == TBAAAccessKind::MayAlias; }
70
71 static TBAAAccessInfo getIncompleteInfo() {
72 return TBAAAccessInfo(TBAAAccessKind::Incomplete,
73 /* BaseType= */ nullptr, /* AccessType= */ nullptr,
74 /* Offset= */ 0, /* Size= */ 0);
75 }
76
77 bool isIncomplete() const { return Kind == TBAAAccessKind::Incomplete; }
78
79 bool operator==(const TBAAAccessInfo &Other) const {
80 return Kind == Other.Kind &&
81 BaseType == Other.BaseType &&
82 AccessType == Other.AccessType &&
83 Offset == Other.Offset &&
84 Size == Other.Size;
85 }
86
87 bool operator!=(const TBAAAccessInfo &Other) const {
88 return !(*this == Other);
89 }
90
91 explicit operator bool() const {
92 return *this != TBAAAccessInfo();
93 }
94
95 /// Kind - The kind of the access descriptor.
96 TBAAAccessKind Kind;
97
98 /// BaseType - The base/leading access type. May be null if this access
99 /// descriptor represents an access that is not considered to be an access
100 /// to an aggregate or union member.
101 llvm::MDNode *BaseType;
102
103 /// AccessType - The final access type. May be null if there is no TBAA
104 /// information available about this access.
105 llvm::MDNode *AccessType;
106
107 /// Offset - The byte offset of the final access within the base one. Must be
108 /// zero if the base access type is not specified.
109 uint64_t Offset;
110
111 /// Size - The size of access, in bytes.
112 uint64_t Size;
113};
114
115/// CodeGenTBAA - This class organizes the cross-module state that is used
116/// while lowering AST types to LLVM types.
117class CodeGenTBAA {
118 ASTContext &Context;
119 llvm::Module &Module;
120 const CodeGenOptions &CodeGenOpts;
121 const LangOptions &Features;
122 MangleContext &MContext;
123
124 // MDHelper - Helper for creating metadata.
125 llvm::MDBuilder MDHelper;
126
127 /// MetadataCache - This maps clang::Types to scalar llvm::MDNodes describing
128 /// them.
129 llvm::DenseMap<const Type *, llvm::MDNode *> MetadataCache;
130 /// This maps clang::Types to a base access type in the type DAG.
131 llvm::DenseMap<const Type *, llvm::MDNode *> BaseTypeMetadataCache;
132 /// This maps TBAA access descriptors to tag nodes.
133 llvm::DenseMap<TBAAAccessInfo, llvm::MDNode *> AccessTagMetadataCache;
134
135 /// StructMetadataCache - This maps clang::Types to llvm::MDNodes describing
136 /// them for struct assignments.
137 llvm::DenseMap<const Type *, llvm::MDNode *> StructMetadataCache;
138
139 llvm::MDNode *Root;
140 llvm::MDNode *Char;
141
142 /// getRoot - This is the mdnode for the root of the metadata type graph
143 /// for this translation unit.
144 llvm::MDNode *getRoot();
145
146 /// getChar - This is the mdnode for "char", which is special, and any types
147 /// considered to be equivalent to it.
148 llvm::MDNode *getChar();
149
150 /// CollectFields - Collect information about the fields of a type for
151 /// !tbaa.struct metadata formation. Return false for an unsupported type.
152 bool CollectFields(uint64_t BaseOffset,
153 QualType Ty,
154 SmallVectorImpl<llvm::MDBuilder::TBAAStructField> &Fields,
155 bool MayAlias);
156
157 /// createScalarTypeNode - A wrapper function to create a metadata node
158 /// describing a scalar type.
159 llvm::MDNode *createScalarTypeNode(StringRef Name, llvm::MDNode *Parent,
160 uint64_t Size);
161
162 /// getTypeInfoHelper - An internal helper function to generate metadata used
163 /// to describe accesses to objects of the given type.
164 llvm::MDNode *getTypeInfoHelper(const Type *Ty);
165
166 /// getBaseTypeInfoHelper - An internal helper function to generate metadata
167 /// used to describe accesses to objects of the given base type.
168 llvm::MDNode *getBaseTypeInfoHelper(const Type *Ty);
169
170public:
171 CodeGenTBAA(ASTContext &Ctx, llvm::Module &M, const CodeGenOptions &CGO,
172 const LangOptions &Features, MangleContext &MContext);
173 ~CodeGenTBAA();
174
175 /// getTypeInfo - Get metadata used to describe accesses to objects of the
176 /// given type.
177 llvm::MDNode *getTypeInfo(QualType QTy);
178
179 /// getAccessInfo - Get TBAA information that describes an access to
180 /// an object of the given type.
181 TBAAAccessInfo getAccessInfo(QualType AccessType);
182
183 /// getVTablePtrAccessInfo - Get the TBAA information that describes an
184 /// access to a virtual table pointer.
185 TBAAAccessInfo getVTablePtrAccessInfo(llvm::Type *VTablePtrType);
186
187 /// getTBAAStructInfo - Get the TBAAStruct MDNode to be used for a memcpy of
188 /// the given type.
189 llvm::MDNode *getTBAAStructInfo(QualType QTy);
190
191 /// getBaseTypeInfo - Get metadata that describes the given base access type.
192 /// Return null if the type is not suitable for use in TBAA access tags.
193 llvm::MDNode *getBaseTypeInfo(QualType QTy);
194
195 /// getAccessTagInfo - Get TBAA tag for a given memory access.
196 llvm::MDNode *getAccessTagInfo(TBAAAccessInfo Info);
197
198 /// mergeTBAAInfoForCast - Get merged TBAA information for the purpose of
199 /// type casts.
200 TBAAAccessInfo mergeTBAAInfoForCast(TBAAAccessInfo SourceInfo,
201 TBAAAccessInfo TargetInfo);
202
203 /// mergeTBAAInfoForConditionalOperator - Get merged TBAA information for the
204 /// purpose of conditional operator.
205 TBAAAccessInfo mergeTBAAInfoForConditionalOperator(TBAAAccessInfo InfoA,
206 TBAAAccessInfo InfoB);
207
208 /// mergeTBAAInfoForMemoryTransfer - Get merged TBAA information for the
209 /// purpose of memory transfer calls.
210 TBAAAccessInfo mergeTBAAInfoForMemoryTransfer(TBAAAccessInfo DestInfo,
211 TBAAAccessInfo SrcInfo);
212};
213
214} // end namespace CodeGen
215} // end namespace clang
216
217namespace llvm {
218
219template<> struct DenseMapInfo<clang::CodeGen::TBAAAccessInfo> {
220 static clang::CodeGen::TBAAAccessInfo getEmptyKey() {
221 unsigned UnsignedKey = DenseMapInfo<unsigned>::getEmptyKey();
222 return clang::CodeGen::TBAAAccessInfo(
223 static_cast<clang::CodeGen::TBAAAccessKind>(UnsignedKey),
224 DenseMapInfo<MDNode *>::getEmptyKey(),
225 DenseMapInfo<MDNode *>::getEmptyKey(),
226 DenseMapInfo<uint64_t>::getEmptyKey(),
227 DenseMapInfo<uint64_t>::getEmptyKey());
228 }
229
230 static clang::CodeGen::TBAAAccessInfo getTombstoneKey() {
231 unsigned UnsignedKey = DenseMapInfo<unsigned>::getTombstoneKey();
232 return clang::CodeGen::TBAAAccessInfo(
233 static_cast<clang::CodeGen::TBAAAccessKind>(UnsignedKey),
234 DenseMapInfo<MDNode *>::getTombstoneKey(),
235 DenseMapInfo<MDNode *>::getTombstoneKey(),
236 DenseMapInfo<uint64_t>::getTombstoneKey(),
237 DenseMapInfo<uint64_t>::getTombstoneKey());
238 }
239
240 static unsigned getHashValue(const clang::CodeGen::TBAAAccessInfo &Val) {
241 auto KindValue = static_cast<unsigned>(Val.Kind);
242 return DenseMapInfo<unsigned>::getHashValue(KindValue) ^
243 DenseMapInfo<MDNode *>::getHashValue(Val.BaseType) ^
244 DenseMapInfo<MDNode *>::getHashValue(Val.AccessType) ^
245 DenseMapInfo<uint64_t>::getHashValue(Val.Offset) ^
246 DenseMapInfo<uint64_t>::getHashValue(Val.Size);
247 }
248
249 static bool isEqual(const clang::CodeGen::TBAAAccessInfo &LHS,
250 const clang::CodeGen::TBAAAccessInfo &RHS) {
251 return LHS == RHS;
252 }
253};
254
255} // end namespace llvm
256
257#endif
258