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 24 namespace clang { 25 class ASTContext; 26 class CodeGenOptions; 27 class LangOptions; 28 class MangleContext; 29 class QualType; 30 class Type; 31 32 namespace 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. 45 class 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 91 public: 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 123 124 namespace llvm { 125 126 template<> 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
