CGRecordLayout.h revision 206084 
1//===--- CGRecordLayout.h - LLVM Record Layout Information ------*- 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#ifndef CLANG_CODEGEN_CGRECORDLAYOUT_H
11#define CLANG_CODEGEN_CGRECORDLAYOUT_H
12
13#include "llvm/ADT/DenseMap.h"
14#include "clang/AST/Decl.h"
15namespace llvm {
16  class Type;
17}
18
19namespace clang {
20namespace CodeGen {
21
22/// CGRecordLayout - This class handles struct and union layout info while
23/// lowering AST types to LLVM types.
24///
25/// These layout objects are only created on demand as IR generation requires.
26class CGRecordLayout {
27  friend class CodeGenTypes;
28
29  CGRecordLayout(const CGRecordLayout&); // DO NOT IMPLEMENT
30  void operator=(const CGRecordLayout&); // DO NOT IMPLEMENT
31
32public:
33  struct BitFieldInfo {
34    BitFieldInfo(unsigned FieldNo,
35                 unsigned Start,
36                 unsigned Size)
37      : FieldNo(FieldNo), Start(Start), Size(Size) {}
38
39    unsigned FieldNo;
40    unsigned Start;
41    unsigned Size;
42  };
43
44private:
45  /// The LLVMType corresponding to this record layout.
46  const llvm::Type *LLVMType;
47
48  /// Map from (non-bit-field) struct field to the corresponding llvm struct
49  /// type field no. This info is populated by record builder.
50  llvm::DenseMap<const FieldDecl *, unsigned> FieldInfo;
51
52  /// Map from (bit-field) struct field to the corresponding llvm struct type
53  /// field no. This info is populated by record builder.
54  llvm::DenseMap<const FieldDecl *, BitFieldInfo> BitFields;
55
56  /// Whether one of the fields in this record layout is a pointer to data
57  /// member, or a struct that contains pointer to data member.
58  bool ContainsPointerToDataMember : 1;
59
60public:
61  CGRecordLayout(const llvm::Type *T, bool ContainsPointerToDataMember)
62    : LLVMType(T), ContainsPointerToDataMember(ContainsPointerToDataMember) {}
63
64  /// \brief Return the LLVM type associated with this record.
65  const llvm::Type *getLLVMType() const {
66    return LLVMType;
67  }
68
69  /// \brief Check whether this struct contains pointers to data members.
70  bool containsPointerToDataMember() const {
71    return ContainsPointerToDataMember;
72  }
73
74  /// \brief Return the BitFieldInfo that corresponds to the field FD.
75  unsigned getLLVMFieldNo(const FieldDecl *FD) const {
76    assert(!FD->isBitField() && "Invalid call for bit-field decl!");
77    assert(FieldInfo.count(FD) && "Invalid field for record!");
78    return FieldInfo.lookup(FD);
79  }
80
81  /// \brief Return llvm::StructType element number that corresponds to the
82  /// field FD.
83  const BitFieldInfo &getBitFieldInfo(const FieldDecl *FD) const {
84    assert(FD->isBitField() && "Invalid call for non bit-field decl!");
85    llvm::DenseMap<const FieldDecl *, BitFieldInfo>::const_iterator
86      it = BitFields.find(FD);
87    assert(it != BitFields.end()  && "Unable to find bitfield info");
88    return it->second;
89  }
90};
91
92}  // end namespace CodeGen
93}  // end namespace clang
94
95#endif
96