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      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 
     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 /// CodeGenTBAA - This class organizes the cross-module state that is used
     39 /// while lowering AST types to LLVM types.
     40 class CodeGenTBAA {
     41   ASTContext &Context;
     42   const CodeGenOptions &CodeGenOpts;
     43   const LangOptions &Features;
     44   MangleContext &MContext;
     45 
     46   // MDHelper - Helper for creating metadata.
     47   llvm::MDBuilder MDHelper;
     48 
     49   /// MetadataCache - This maps clang::Types to llvm::MDNodes describing them.
     50   llvm::DenseMap<const Type *, llvm::MDNode *> MetadataCache;
     51 
     52   /// StructMetadataCache - This maps clang::Types to llvm::MDNodes describing
     53   /// them for struct assignments.
     54   llvm::DenseMap<const Type *, llvm::MDNode *> StructMetadataCache;
     55 
     56   llvm::MDNode *Root;
     57   llvm::MDNode *Char;
     58 
     59   /// getRoot - This is the mdnode for the root of the metadata type graph
     60   /// for this translation unit.
     61   llvm::MDNode *getRoot();
     62 
     63   /// getChar - This is the mdnode for "char", which is special, and any types
     64   /// considered to be equivalent to it.
     65   llvm::MDNode *getChar();
     66 
     67   /// CollectFields - Collect information about the fields of a type for
     68   /// !tbaa.struct metadata formation. Return false for an unsupported type.
     69   bool CollectFields(uint64_t BaseOffset,
     70                      QualType Ty,
     71                      SmallVectorImpl<llvm::MDBuilder::TBAAStructField> &Fields,
     72                      bool MayAlias);
     73 
     74 public:
     75   CodeGenTBAA(ASTContext &Ctx, llvm::LLVMContext &VMContext,
     76               const CodeGenOptions &CGO,
     77               const LangOptions &Features,
     78               MangleContext &MContext);
     79   ~CodeGenTBAA();
     80 
     81   /// getTBAAInfo - Get the TBAA MDNode to be used for a dereference
     82   /// of the given type.
     83   llvm::MDNode *getTBAAInfo(QualType QTy);
     84 
     85   /// getTBAAInfoForVTablePtr - Get the TBAA MDNode to be used for a
     86   /// dereference of a vtable pointer.
     87   llvm::MDNode *getTBAAInfoForVTablePtr();
     88 
     89   /// getTBAAStructInfo - Get the TBAAStruct MDNode to be used for a memcpy of
     90   /// the given type.
     91   llvm::MDNode *getTBAAStructInfo(QualType QTy);
     92 };
     93 
     94 }  // end namespace CodeGen
     95 }  // end namespace clang
     96 
     97 #endif
     98