MCSectionMachO.h revision f2dc4aa562e2478a73fe5aeeeec16b1e496a0642 
1//===- MCSectionMachO.h - MachO Machine Code Sections -----------*- 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 file declares the MCSectionMachO class.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_MC_MCSECTIONMACHO_H
15#define LLVM_MC_MCSECTIONMACHO_H
16
17#include "llvm/MC/MCSection.h"
18
19namespace llvm {
20
21/// MCSectionMachO - This represents a section on a Mach-O system (used by
22/// Mac OS X).  On a Mac system, these are also described in
23/// /usr/include/mach-o/loader.h.
24class MCSectionMachO : public MCSection {
25  char SegmentName[16];  // Not necessarily null terminated!
26  char SectionName[16];  // Not necessarily null terminated!
27
28  /// TypeAndAttributes - This is the SECTION_TYPE and SECTION_ATTRIBUTES
29  /// field of a section, drawn from the enums below.
30  unsigned TypeAndAttributes;
31
32  /// Reserved2 - The 'reserved2' field of a section, used to represent the
33  /// size of stubs, for example.
34  unsigned Reserved2;
35
36  MCSectionMachO(StringRef Segment, StringRef Section,
37                 unsigned TAA, unsigned reserved2, SectionKind K);
38  friend class MCContext;
39public:
40
41  /// These are the section type and attributes fields.  A MachO section can
42  /// have only one Type, but can have any of the attributes specified.
43  enum {
44    // TypeAndAttributes bitmasks.
45    SECTION_TYPE       = 0x000000FFU,
46    SECTION_ATTRIBUTES = 0xFFFFFF00U,
47
48    // Valid section types.
49
50    /// S_REGULAR - Regular section.
51    S_REGULAR                    = 0x00U,
52    /// S_ZEROFILL - Zero fill on demand section.
53    S_ZEROFILL                   = 0x01U,
54    /// S_CSTRING_LITERALS - Section with literal C strings.
55    S_CSTRING_LITERALS           = 0x02U,
56    /// S_4BYTE_LITERALS - Section with 4 byte literals.
57    S_4BYTE_LITERALS             = 0x03U,
58    /// S_8BYTE_LITERALS - Section with 8 byte literals.
59    S_8BYTE_LITERALS             = 0x04U,
60    /// S_LITERAL_POINTERS - Section with pointers to literals.
61    S_LITERAL_POINTERS           = 0x05U,
62    /// S_NON_LAZY_SYMBOL_POINTERS - Section with non-lazy symbol pointers.
63    S_NON_LAZY_SYMBOL_POINTERS   = 0x06U,
64    /// S_LAZY_SYMBOL_POINTERS - Section with lazy symbol pointers.
65    S_LAZY_SYMBOL_POINTERS       = 0x07U,
66    /// S_SYMBOL_STUBS - Section with symbol stubs, byte size of stub in
67    /// the Reserved2 field.
68    S_SYMBOL_STUBS               = 0x08U,
69    /// S_SYMBOL_STUBS - Section with only function pointers for
70    /// initialization.
71    S_MOD_INIT_FUNC_POINTERS     = 0x09U,
72    /// S_MOD_INIT_FUNC_POINTERS - Section with only function pointers for
73    /// termination.
74    S_MOD_TERM_FUNC_POINTERS     = 0x0AU,
75    /// S_COALESCED - Section contains symbols that are to be coalesced.
76    S_COALESCED                  = 0x0BU,
77    /// S_GB_ZEROFILL - Zero fill on demand section (that can be larger than 4
78    /// gigabytes).
79    S_GB_ZEROFILL                = 0x0CU,
80    /// S_INTERPOSING - Section with only pairs of function pointers for
81    /// interposing.
82    S_INTERPOSING                = 0x0DU,
83    /// S_16BYTE_LITERALS - Section with only 16 byte literals.
84    S_16BYTE_LITERALS            = 0x0EU,
85    /// S_DTRACE_DOF - Section contains DTrace Object Format.
86    S_DTRACE_DOF                 = 0x0FU,
87    /// S_LAZY_DYLIB_SYMBOL_POINTERS - Section with lazy symbol pointers to
88    /// lazy loaded dylibs.
89    S_LAZY_DYLIB_SYMBOL_POINTERS = 0x10U,
90    /// S_THREAD_LOCAL_REGULAR - Section with ....
91    S_THREAD_LOCAL_REGULAR = 0x11U,
92    /// S_THREAD_LOCAL_ZEROFILL - Thread local zerofill section.
93    S_THREAD_LOCAL_ZEROFILL = 0x12U,
94    /// S_THREAD_LOCAL_VARIABLES - Section with thread local variable structure
95    /// data.
96    S_THREAD_LOCAL_VARIABLES = 0x13U,
97    /// S_THREAD_LOCAL_VARIABLE_POINTERS - Section with ....
98    S_THREAD_LOCAL_VARIABLE_POINTERS = 0x14U,
99    /// S_THREAD_LOCAL_INIT_FUNCTION_POINTERS - Section with thread local
100    /// variable initialization pointers to functions.
101    S_THREAD_LOCAL_INIT_FUNCTION_POINTERS = 0x15U,
102
103    LAST_KNOWN_SECTION_TYPE = S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
104
105
106    // Valid section attributes.
107
108    /// S_ATTR_PURE_INSTRUCTIONS - Section contains only true machine
109    /// instructions.
110    S_ATTR_PURE_INSTRUCTIONS   = 1U << 31,
111    /// S_ATTR_NO_TOC - Section contains coalesced symbols that are not to be
112    /// in a ranlib table of contents.
113    S_ATTR_NO_TOC              = 1U << 30,
114    /// S_ATTR_STRIP_STATIC_SYMS - Ok to strip static symbols in this section
115    /// in files with the MY_DYLDLINK flag.
116    S_ATTR_STRIP_STATIC_SYMS   = 1U << 29,
117    /// S_ATTR_NO_DEAD_STRIP - No dead stripping.
118    S_ATTR_NO_DEAD_STRIP       = 1U << 28,
119    /// S_ATTR_LIVE_SUPPORT - Blocks are live if they reference live blocks.
120    S_ATTR_LIVE_SUPPORT        = 1U << 27,
121    /// S_ATTR_SELF_MODIFYING_CODE - Used with i386 code stubs written on by
122    /// dyld.
123    S_ATTR_SELF_MODIFYING_CODE = 1U << 26,
124    /// S_ATTR_DEBUG - A debug section.
125    S_ATTR_DEBUG               = 1U << 25,
126    /// S_ATTR_SOME_INSTRUCTIONS - Section contains some machine instructions.
127    S_ATTR_SOME_INSTRUCTIONS   = 1U << 10,
128    /// S_ATTR_EXT_RELOC - Section has external relocation entries.
129    S_ATTR_EXT_RELOC           = 1U << 9,
130    /// S_ATTR_LOC_RELOC - Section has local relocation entries.
131    S_ATTR_LOC_RELOC           = 1U << 8
132  };
133
134  StringRef getSegmentName() const {
135    // SegmentName is not necessarily null terminated!
136    if (SegmentName[15])
137      return StringRef(SegmentName, 16);
138    return StringRef(SegmentName);
139  }
140  StringRef getSectionName() const {
141    // SectionName is not necessarily null terminated!
142    if (SectionName[15])
143      return StringRef(SectionName, 16);
144    return StringRef(SectionName);
145  }
146
147  unsigned getTypeAndAttributes() const { return TypeAndAttributes; }
148  unsigned getStubSize() const { return Reserved2; }
149
150  unsigned getType() const { return TypeAndAttributes & SECTION_TYPE; }
151  bool hasAttribute(unsigned Value) const {
152    return (TypeAndAttributes & Value) != 0;
153  }
154
155  /// ParseSectionSpecifier - Parse the section specifier indicated by "Spec".
156  /// This is a string that can appear after a .section directive in a mach-o
157  /// flavored .s file.  If successful, this fills in the specified Out
158  /// parameters and returns an empty string.  When an invalid section
159  /// specifier is present, this returns a string indicating the problem.
160  static std::string ParseSectionSpecifier(StringRef Spec,       // In.
161                                           StringRef &Segment,   // Out.
162                                           StringRef &Section,   // Out.
163                                           unsigned  &TAA,       // Out.
164                                           unsigned  &StubSize); // Out.
165
166  virtual void PrintSwitchToSection(const MCAsmInfo &MAI,
167                                    raw_ostream &OS) const;
168  virtual bool UseCodeAlign() const;
169  virtual bool isVirtualSection() const;
170
171  static bool classof(const MCSection *S) {
172    return S->getVariant() == SV_MachO;
173  }
174  static bool classof(const MCSectionMachO *) { return true; }
175};
176
177} // end namespace llvm
178
179#endif
180