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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/ADT/StringRef.h"
18 #include "llvm/MC/MCSection.h"
19 
20 namespace llvm {
21 
22 /// MCSectionMachO - This represents a section on a Mach-O system (used by
23 /// Mac OS X).  On a Mac system, these are also described in
24 /// /usr/include/mach-o/loader.h.
25 class MCSectionMachO : public MCSection {
26   char SegmentName[16];  // Not necessarily null terminated!
27   char SectionName[16];  // Not necessarily null terminated!
28 
29   /// TypeAndAttributes - This is the SECTION_TYPE and SECTION_ATTRIBUTES
30   /// field of a section, drawn from the enums below.
31   unsigned TypeAndAttributes;
32 
33   /// Reserved2 - The 'reserved2' field of a section, used to represent the
34   /// size of stubs, for example.
35   unsigned Reserved2;
36 
37   MCSectionMachO(StringRef Segment, StringRef Section,
38                  unsigned TAA, unsigned reserved2, SectionKind K);
39   friend class MCContext;
40 public:
41 
42   /// These are the section type and attributes fields.  A MachO section can
43   /// have only one Type, but can have any of the attributes specified.
44   enum {
45     // TypeAndAttributes bitmasks.
46     SECTION_TYPE       = 0x000000FFU,
47     SECTION_ATTRIBUTES = 0xFFFFFF00U,
48 
49     // Valid section types.
50 
51     /// S_REGULAR - Regular section.
52     S_REGULAR                    = 0x00U,
53     /// S_ZEROFILL - Zero fill on demand section.
54     S_ZEROFILL                   = 0x01U,
55     /// S_CSTRING_LITERALS - Section with literal C strings.
56     S_CSTRING_LITERALS           = 0x02U,
57     /// S_4BYTE_LITERALS - Section with 4 byte literals.
58     S_4BYTE_LITERALS             = 0x03U,
59     /// S_8BYTE_LITERALS - Section with 8 byte literals.
60     S_8BYTE_LITERALS             = 0x04U,
61     /// S_LITERAL_POINTERS - Section with pointers to literals.
62     S_LITERAL_POINTERS           = 0x05U,
63     /// S_NON_LAZY_SYMBOL_POINTERS - Section with non-lazy symbol pointers.
64     S_NON_LAZY_SYMBOL_POINTERS   = 0x06U,
65     /// S_LAZY_SYMBOL_POINTERS - Section with lazy symbol pointers.
66     S_LAZY_SYMBOL_POINTERS       = 0x07U,
67     /// S_SYMBOL_STUBS - Section with symbol stubs, byte size of stub in
68     /// the Reserved2 field.
69     S_SYMBOL_STUBS               = 0x08U,
70     /// S_MOD_INIT_FUNC_POINTERS - Section with only function pointers for
71     /// initialization.
72     S_MOD_INIT_FUNC_POINTERS     = 0x09U,
73     /// S_MOD_TERM_FUNC_POINTERS - Section with only function pointers for
74     /// termination.
75     S_MOD_TERM_FUNC_POINTERS     = 0x0AU,
76     /// S_COALESCED - Section contains symbols that are to be coalesced.
77     S_COALESCED                  = 0x0BU,
78     /// S_GB_ZEROFILL - Zero fill on demand section (that can be larger than 4
79     /// gigabytes).
80     S_GB_ZEROFILL                = 0x0CU,
81     /// S_INTERPOSING - Section with only pairs of function pointers for
82     /// interposing.
83     S_INTERPOSING                = 0x0DU,
84     /// S_16BYTE_LITERALS - Section with only 16 byte literals.
85     S_16BYTE_LITERALS            = 0x0EU,
86     /// S_DTRACE_DOF - Section contains DTrace Object Format.
87     S_DTRACE_DOF                 = 0x0FU,
88     /// S_LAZY_DYLIB_SYMBOL_POINTERS - Section with lazy symbol pointers to
89     /// lazy loaded dylibs.
90     S_LAZY_DYLIB_SYMBOL_POINTERS = 0x10U,
91     /// S_THREAD_LOCAL_REGULAR - Section with ....
92     S_THREAD_LOCAL_REGULAR = 0x11U,
93     /// S_THREAD_LOCAL_ZEROFILL - Thread local zerofill section.
94     S_THREAD_LOCAL_ZEROFILL = 0x12U,
95     /// S_THREAD_LOCAL_VARIABLES - Section with thread local variable structure
96     /// data.
97     S_THREAD_LOCAL_VARIABLES = 0x13U,
98     /// S_THREAD_LOCAL_VARIABLE_POINTERS - Section with ....
99     S_THREAD_LOCAL_VARIABLE_POINTERS = 0x14U,
100     /// S_THREAD_LOCAL_INIT_FUNCTION_POINTERS - Section with thread local
101     /// variable initialization pointers to functions.
102     S_THREAD_LOCAL_INIT_FUNCTION_POINTERS = 0x15U,
103 
104     LAST_KNOWN_SECTION_TYPE = S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
105 
106 
107     // Valid section attributes.
108 
109     /// S_ATTR_PURE_INSTRUCTIONS - Section contains only true machine
110     /// instructions.
111     S_ATTR_PURE_INSTRUCTIONS   = 1U << 31,
112     /// S_ATTR_NO_TOC - Section contains coalesced symbols that are not to be
113     /// in a ranlib table of contents.
114     S_ATTR_NO_TOC              = 1U << 30,
115     /// S_ATTR_STRIP_STATIC_SYMS - Ok to strip static symbols in this section
116     /// in files with the MY_DYLDLINK flag.
117     S_ATTR_STRIP_STATIC_SYMS   = 1U << 29,
118     /// S_ATTR_NO_DEAD_STRIP - No dead stripping.
119     S_ATTR_NO_DEAD_STRIP       = 1U << 28,
120     /// S_ATTR_LIVE_SUPPORT - Blocks are live if they reference live blocks.
121     S_ATTR_LIVE_SUPPORT        = 1U << 27,
122     /// S_ATTR_SELF_MODIFYING_CODE - Used with i386 code stubs written on by
123     /// dyld.
124     S_ATTR_SELF_MODIFYING_CODE = 1U << 26,
125     /// S_ATTR_DEBUG - A debug section.
126     S_ATTR_DEBUG               = 1U << 25,
127     /// S_ATTR_SOME_INSTRUCTIONS - Section contains some machine instructions.
128     S_ATTR_SOME_INSTRUCTIONS   = 1U << 10,
129     /// S_ATTR_EXT_RELOC - Section has external relocation entries.
130     S_ATTR_EXT_RELOC           = 1U << 9,
131     /// S_ATTR_LOC_RELOC - Section has local relocation entries.
132     S_ATTR_LOC_RELOC           = 1U << 8
133   };
134 
getSegmentName()135   StringRef getSegmentName() const {
136     // SegmentName is not necessarily null terminated!
137     if (SegmentName[15])
138       return StringRef(SegmentName, 16);
139     return StringRef(SegmentName);
140   }
getSectionName()141   StringRef getSectionName() const {
142     // SectionName is not necessarily null terminated!
143     if (SectionName[15])
144       return StringRef(SectionName, 16);
145     return StringRef(SectionName);
146   }
147 
getLabelBeginName()148   virtual std::string getLabelBeginName() const {
149     return StringRef(getSegmentName().str() + getSectionName().str() + "_begin");
150   }
151 
getLabelEndName()152   virtual std::string getLabelEndName() const {
153     return StringRef(getSegmentName().str() + getSectionName().str() + "_end");
154   }
155 
getTypeAndAttributes()156   unsigned getTypeAndAttributes() const { return TypeAndAttributes; }
getStubSize()157   unsigned getStubSize() const { return Reserved2; }
158 
getType()159   unsigned getType() const { return TypeAndAttributes & SECTION_TYPE; }
hasAttribute(unsigned Value)160   bool hasAttribute(unsigned Value) const {
161     return (TypeAndAttributes & Value) != 0;
162   }
163 
164   /// ParseSectionSpecifier - Parse the section specifier indicated by "Spec".
165   /// This is a string that can appear after a .section directive in a mach-o
166   /// flavored .s file.  If successful, this fills in the specified Out
167   /// parameters and returns an empty string.  When an invalid section
168   /// specifier is present, this returns a string indicating the problem.
169   /// If no TAA was parsed, TAA is not altered, and TAAWasSet becomes false.
170   static std::string ParseSectionSpecifier(StringRef Spec,       // In.
171                                            StringRef &Segment,   // Out.
172                                            StringRef &Section,   // Out.
173                                            unsigned  &TAA,       // Out.
174                                            bool      &TAAParsed, // Out.
175                                            unsigned  &StubSize); // Out.
176 
177   virtual void PrintSwitchToSection(const MCAsmInfo &MAI,
178                                     raw_ostream &OS,
179                                     const MCExpr *Subsection) const;
180   virtual bool UseCodeAlign() const;
181   virtual bool isVirtualSection() const;
182 
classof(const MCSection * S)183   static bool classof(const MCSection *S) {
184     return S->getVariant() == SV_MachO;
185   }
186 };
187 
188 } // end namespace llvm
189 
190 #endif
191