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