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/Basic/LLVM.h" 19 #include "llvm/ADT/DenseMap.h" 20 #include "llvm/IR/MDBuilder.h" 21 22 namespace llvm { 23 class LLVMContext; 24 class MDNode; 25 } 26 27 namespace clang { 28 class ASTContext; 29 class CodeGenOptions; 30 class LangOptions; 31 class MangleContext; 32 class QualType; 33 class Type; 34 35 namespace 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. 48 class 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 94 public: 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 126 127 namespace llvm { 128 129 template<> 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
