MCSection.h revision ff4bc460c52c1f285d8a56da173641bf92d49e3f 
1//===- MCSection.h - 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 MCSection class.
11//
12//===----------------------------------------------------------------------===//
13
14#ifndef LLVM_MC_MCSECTION_H
15#define LLVM_MC_MCSECTION_H
16
17#include <string>
18#include "llvm/ADT/StringRef.h"
19#include "llvm/MC/SectionKind.h"
20
21namespace llvm {
22  class MCContext;
23  class TargetAsmInfo;
24  class raw_ostream;
25
26  /// MCSection - Instances of this class represent a uniqued identifier for a
27  /// section in the current translation unit.  The MCContext class uniques and
28  /// creates these.
29  class MCSection {
30    MCSection(const MCSection&);      // DO NOT IMPLEMENT
31    void operator=(const MCSection&); // DO NOT IMPLEMENT
32  protected:
33    MCSection(SectionKind K) : Kind(K) {}
34    SectionKind Kind;
35  public:
36    virtual ~MCSection();
37
38    SectionKind getKind() const { return Kind; }
39
40    virtual void PrintSwitchToSection(const TargetAsmInfo &TAI,
41                                      raw_ostream &OS) const = 0;
42  };
43
44
45  class MCSectionELF : public MCSection {
46    std::string Name;
47
48    /// IsDirective - This is true if the section name is a directive, not
49    /// something that should be printed with ".section".
50    ///
51    /// FIXME: This is a hack.  Switch to a semantic view of the section instead
52    /// of a syntactic one.
53    bool IsDirective;
54
55    MCSectionELF(const StringRef &Name, bool IsDirective, SectionKind K,
56                 MCContext &Ctx);
57  public:
58
59    static MCSectionELF *Create(const StringRef &Name, bool IsDirective,
60                                SectionKind K, MCContext &Ctx);
61
62    const std::string &getName() const { return Name; }
63    bool isDirective() const { return IsDirective; }
64
65
66    virtual void PrintSwitchToSection(const TargetAsmInfo &TAI,
67                                      raw_ostream &OS) const;
68  };
69
70
71  /// MCSectionMachO - This represents a section on a Mach-O system (used by
72  /// Mac OS X).  On a Mac system, these are also described in
73  /// /usr/include/mach-o/loader.h.
74  class MCSectionMachO : public MCSection {
75    char SegmentName[16];  // Not necessarily null terminated!
76    char SectionName[16];  // Not necessarily null terminated!
77
78    /// TypeAndAttributes - This is the SECTION_TYPE and SECTION_ATTRIBUTES
79    /// field of a section, drawn from the enums below.
80    unsigned TypeAndAttributes;
81
82    /// Reserved2 - The 'reserved2' field of a section, used to represent the
83    /// size of stubs, for example.
84    unsigned Reserved2;
85
86    MCSectionMachO(const StringRef &Segment, const StringRef &Section,
87                   unsigned TAA, unsigned reserved2, SectionKind K)
88      : MCSection(K), TypeAndAttributes(TAA), Reserved2(reserved2) {
89      assert(Segment.size() <= 16 && Section.size() <= 16 &&
90             "Segment or section string too long");
91      for (unsigned i = 0; i != 16; ++i) {
92        if (i < Segment.size())
93          SegmentName[i] = Segment[i];
94        else
95          SegmentName[i] = 0;
96
97        if (i < Section.size())
98          SectionName[i] = Section[i];
99        else
100          SectionName[i] = 0;
101      }
102    }
103  public:
104
105    static MCSectionMachO *Create(const StringRef &Segment,
106                                  const StringRef &Section,
107                                  unsigned TypeAndAttributes,
108                                  unsigned Reserved2,
109                                  SectionKind K, MCContext &Ctx);
110
111    /// These are the section type and attributes fields.  A MachO section can
112    /// have only one Type, but can have any of the attributes specified.
113    enum {
114      // TypeAndAttributes bitmasks.
115      SECTION_TYPE       = 0x000000FFU,
116      SECTION_ATTRIBUTES = 0xFFFFFF00U,
117
118      // Valid section types.
119
120      /// S_REGULAR - Regular section.
121      S_REGULAR                    = 0x00U,
122      /// S_ZEROFILL - Zero fill on demand section.
123      S_ZEROFILL                   = 0x01U,
124      /// S_CSTRING_LITERALS - Section with literal C strings.
125      S_CSTRING_LITERALS           = 0x02U,
126      /// S_4BYTE_LITERALS - Section with 4 byte literals.
127      S_4BYTE_LITERALS             = 0x03U,
128      /// S_8BYTE_LITERALS - Section with 8 byte literals.
129      S_8BYTE_LITERALS             = 0x04U,
130      /// S_LITERAL_POINTERS - Section with pointers to literals.
131      S_LITERAL_POINTERS           = 0x05U,
132      /// S_NON_LAZY_SYMBOL_POINTERS - Section with non-lazy symbol pointers.
133      S_NON_LAZY_SYMBOL_POINTERS   = 0x06U,
134      /// S_LAZY_SYMBOL_POINTERS - Section with lazy symbol pointers.
135      S_LAZY_SYMBOL_POINTERS       = 0x07U,
136      /// S_SYMBOL_STUBS - Section with symbol stubs, byte size of stub in
137      /// the Reserved2 field.
138      S_SYMBOL_STUBS               = 0x08U,
139      /// S_SYMBOL_STUBS - Section with only function pointers for
140      /// initialization.
141      S_MOD_INIT_FUNC_POINTERS     = 0x09U,
142      /// S_MOD_INIT_FUNC_POINTERS - Section with only function pointers for
143      /// termination.
144      S_MOD_TERM_FUNC_POINTERS     = 0x0AU,
145      /// S_COALESCED - Section contains symbols that are to be coalesced.
146      S_COALESCED                  = 0x0BU,
147      /// S_GB_ZEROFILL - Zero fill on demand section (that can be larger than 4
148      /// gigabytes).
149      S_GB_ZEROFILL                = 0x0CU,
150      /// S_INTERPOSING - Section with only pairs of function pointers for
151      /// interposing.
152      S_INTERPOSING                = 0x0DU,
153      /// S_16BYTE_LITERALS - Section with only 16 byte literals.
154      S_16BYTE_LITERALS            = 0x0EU,
155      /// S_DTRACE_DOF - Section contains DTrace Object Format.
156      S_DTRACE_DOF                 = 0x0FU,
157      /// S_LAZY_DYLIB_SYMBOL_POINTERS - Section with lazy symbol pointers to
158      /// lazy loaded dylibs.
159      S_LAZY_DYLIB_SYMBOL_POINTERS = 0x10U,
160
161      LAST_KNOWN_SECTION_TYPE = S_LAZY_DYLIB_SYMBOL_POINTERS,
162
163
164      // Valid section attributes.
165
166      /// S_ATTR_PURE_INSTRUCTIONS - Section contains only true machine
167      /// instructions.
168      S_ATTR_PURE_INSTRUCTIONS   = 1U << 31,
169      /// S_ATTR_NO_TOC - Section contains coalesced symbols that are not to be
170      /// in a ranlib table of contents.
171      S_ATTR_NO_TOC              = 1U << 30,
172      /// S_ATTR_STRIP_STATIC_SYMS - Ok to strip static symbols in this section
173      /// in files with the MY_DYLDLINK flag.
174      S_ATTR_STRIP_STATIC_SYMS   = 1U << 29,
175      /// S_ATTR_NO_DEAD_STRIP - No dead stripping.
176      S_ATTR_NO_DEAD_STRIP       = 1U << 28,
177      /// S_ATTR_LIVE_SUPPORT - Blocks are live if they reference live blocks.
178      S_ATTR_LIVE_SUPPORT        = 1U << 27,
179      /// S_ATTR_SELF_MODIFYING_CODE - Used with i386 code stubs written on by
180      /// dyld.
181      S_ATTR_SELF_MODIFYING_CODE = 1U << 26,
182      /// S_ATTR_DEBUG - A debug section.
183      S_ATTR_DEBUG               = 1U << 25,
184      /// S_ATTR_SOME_INSTRUCTIONS - Section contains some machine instructions.
185      S_ATTR_SOME_INSTRUCTIONS   = 1U << 10,
186      /// S_ATTR_EXT_RELOC - Section has external relocation entries.
187      S_ATTR_EXT_RELOC           = 1U << 9,
188      /// S_ATTR_LOC_RELOC - Section has local relocation entries.
189      S_ATTR_LOC_RELOC           = 1U << 8
190    };
191
192    StringRef getSegmentName() const {
193      // SegmentName is not necessarily null terminated!
194      if (SegmentName[15])
195        return StringRef(SegmentName, 16);
196      return StringRef(SegmentName);
197    }
198    StringRef getSectionName() const {
199      // SectionName is not necessarily null terminated!
200      if (SectionName[15])
201        return StringRef(SectionName, 16);
202      return StringRef(SectionName);
203    }
204
205    unsigned getTypeAndAttributes() const { return TypeAndAttributes; }
206
207
208    /// ParseSectionSpecifier - Parse the section specifier indicated by "Spec".
209    /// This is a string that can appear after a .section directive in a mach-o
210    /// flavored .s file.  If successful, this fills in the specified Out
211    /// parameters and returns an empty string.  When an invalid section
212    /// specifier is present, this returns a string indicating the problem.
213    static std::string ParseSectionSpecifier(StringRef Spec,       // In.
214                                             StringRef &Segment,   // Out.
215                                             StringRef &Section,   // Out.
216                                             unsigned  &TAA,       // Out.
217                                             unsigned  &StubSize); // Out.
218
219    virtual void PrintSwitchToSection(const TargetAsmInfo &TAI,
220                                      raw_ostream &OS) const;
221  };
222
223  class MCSectionCOFF : public MCSection {
224    std::string Name;
225
226    /// IsDirective - This is true if the section name is a directive, not
227    /// something that should be printed with ".section".
228    ///
229    /// FIXME: This is a hack.  Switch to a semantic view of the section instead
230    /// of a syntactic one.
231    bool IsDirective;
232
233    MCSectionCOFF(const StringRef &Name, bool IsDirective, SectionKind K,
234                  MCContext &Ctx);
235  public:
236
237    static MCSectionCOFF *Create(const StringRef &Name, bool IsDirective,
238                                   SectionKind K, MCContext &Ctx);
239
240    const std::string &getName() const { return Name; }
241    bool isDirective() const { return IsDirective; }
242
243    virtual void PrintSwitchToSection(const TargetAsmInfo &TAI,
244                                      raw_ostream &OS) const;
245  };
246
247} // end namespace llvm
248
249#endif
250