CodeGenTBAA.h revision 9aaee92faa84a54a78cc298b1d281c4bce39c122 
1//===--- CodeGenTBAA.h - TBAA information for LLVM CodeGen ------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This is the code that manages TBAA information and defines the TBAA policy
11// for the optimizer to use.
12//
13//===----------------------------------------------------------------------===//
14
15#ifndef CLANG_CODEGEN_CODEGENTBAA_H
16#define CLANG_CODEGEN_CODEGENTBAA_H
17
18#include "clang/Basic/LLVM.h"
19#include "llvm/ADT/DenseMap.h"
20#include "llvm/IR/MDBuilder.h"
21
22namespace llvm {
23  class LLVMContext;
24  class MDNode;
25}
26
27namespace clang {
28  class ASTContext;
29  class CodeGenOptions;
30  class LangOptions;
31  class MangleContext;
32  class QualType;
33  class Type;
34
35namespace CodeGen {
36  class CGRecordLayout;
37
38  struct TBAAPathTag {
39    TBAAPathTag(const Type *B, const llvm::MDNode *A, uint64_t O)
40      : BaseT(B), AccessN(A), Offset(O) {}
41    const Type *BaseT;
42    const llvm::MDNode *AccessN;
43    uint64_t Offset;
44  };
45
46/// CodeGenTBAA - This class organizes the cross-module state that is used
47/// while lowering AST types to LLVM types.
48class CodeGenTBAA {
49  ASTContext &Context;
50  const CodeGenOptions &CodeGenOpts;
51  const LangOptions &Features;
52  MangleContext &MContext;
53
54  // MDHelper - Helper for creating metadata.
55  llvm::MDBuilder MDHelper;
56
57  /// MetadataCache - This maps clang::Types to scalar llvm::MDNodes describing
58  /// them.
59  llvm::DenseMap<const Type *, llvm::MDNode *> MetadataCache;
60  /// This maps clang::Types to a struct node in the type DAG.
61  llvm::DenseMap<const Type *, llvm::MDNode *> StructTypeMetadataCache;
62  /// This maps TBAAPathTags to a tag node.
63  llvm::DenseMap<TBAAPathTag, llvm::MDNode *> StructTagMetadataCache;
64  /// This maps a scalar type to a scalar tag node.
65  llvm::DenseMap<const llvm::MDNode *, llvm::MDNode *> ScalarTagMetadataCache;
66
67  /// StructMetadataCache - This maps clang::Types to llvm::MDNodes describing
68  /// them for struct assignments.
69  llvm::DenseMap<const Type *, llvm::MDNode *> StructMetadataCache;
70
71  llvm::MDNode *Root;
72  llvm::MDNode *Char;
73
74  /// getRoot - This is the mdnode for the root of the metadata type graph
75  /// for this translation unit.
76  llvm::MDNode *getRoot();
77
78  /// getChar - This is the mdnode for "char", which is special, and any types
79  /// considered to be equivalent to it.
80  llvm::MDNode *getChar();
81
82  /// CollectFields - Collect information about the fields of a type for
83  /// !tbaa.struct metadata formation. Return false for an unsupported type.
84  bool CollectFields(uint64_t BaseOffset,
85                     QualType Ty,
86                     SmallVectorImpl<llvm::MDBuilder::TBAAStructField> &Fields,
87                     bool MayAlias);
88
89  /// A wrapper function to create a scalar type. For struct-path aware TBAA,
90  /// the scalar type has the same format as the struct type: name, offset,
91  /// pointer to another node in the type DAG.
92  llvm::MDNode *createTBAAScalarType(StringRef Name, llvm::MDNode *Parent);
93
94public:
95  CodeGenTBAA(ASTContext &Ctx, llvm::LLVMContext &VMContext,
96              const CodeGenOptions &CGO,
97              const LangOptions &Features,
98              MangleContext &MContext);
99  ~CodeGenTBAA();
100
101  /// getTBAAInfo - Get the TBAA MDNode to be used for a dereference
102  /// of the given type.
103  llvm::MDNode *getTBAAInfo(QualType QTy);
104
105  /// getTBAAInfoForVTablePtr - Get the TBAA MDNode to be used for a
106  /// dereference of a vtable pointer.
107  llvm::MDNode *getTBAAInfoForVTablePtr();
108
109  /// getTBAAStructInfo - Get the TBAAStruct MDNode to be used for a memcpy of
110  /// the given type.
111  llvm::MDNode *getTBAAStructInfo(QualType QTy);
112
113  /// Get the MDNode in the type DAG for given struct type QType.
114  llvm::MDNode *getTBAAStructTypeInfo(QualType QType);
115  /// Get the tag MDNode for a given base type, the actual scalar access MDNode
116  /// and offset into the base type.
117  llvm::MDNode *getTBAAStructTagInfo(QualType BaseQType,
118                                     llvm::MDNode *AccessNode, uint64_t Offset);
119
120  /// Get the scalar tag MDNode for a given scalar type.
121  llvm::MDNode *getTBAAScalarTagInfo(llvm::MDNode *AccessNode);
122};
123
124}  // end namespace CodeGen
125}  // end namespace clang
126
127namespace llvm {
128
129template<> struct DenseMapInfo<clang::CodeGen::TBAAPathTag> {
130  static clang::CodeGen::TBAAPathTag getEmptyKey() {
131    return clang::CodeGen::TBAAPathTag(
132      DenseMapInfo<const clang::Type *>::getEmptyKey(),
133      DenseMapInfo<const MDNode *>::getEmptyKey(),
134      DenseMapInfo<uint64_t>::getEmptyKey());
135  }
136
137  static clang::CodeGen::TBAAPathTag getTombstoneKey() {
138    return clang::CodeGen::TBAAPathTag(
139      DenseMapInfo<const clang::Type *>::getTombstoneKey(),
140      DenseMapInfo<const MDNode *>::getTombstoneKey(),
141      DenseMapInfo<uint64_t>::getTombstoneKey());
142  }
143
144  static unsigned getHashValue(const clang::CodeGen::TBAAPathTag &Val) {
145    return DenseMapInfo<const clang::Type *>::getHashValue(Val.BaseT) ^
146           DenseMapInfo<const MDNode *>::getHashValue(Val.AccessN) ^
147           DenseMapInfo<uint64_t>::getHashValue(Val.Offset);
148  }
149
150  static bool isEqual(const clang::CodeGen::TBAAPathTag &LHS,
151                      const clang::CodeGen::TBAAPathTag &RHS) {
152    return LHS.BaseT == RHS.BaseT &&
153           LHS.AccessN == RHS.AccessN &&
154           LHS.Offset == RHS.Offset;
155  }
156};
157
158}  // end namespace llvm
159
160#endif
161