LLVM  3.7.0
SectionKind.h
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1 //===-- llvm/Target/TargetLoweringObjectFile.h - Object Info ----*- 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 implements classes used to handle lowerings specific to common
11 // object file formats.
12 //
13 //===----------------------------------------------------------------------===//
14 
15 #ifndef LLVM_MC_SECTIONKIND_H
16 #define LLVM_MC_SECTIONKIND_H
17 
18 namespace llvm {
19 
20 /// SectionKind - This is a simple POD value that classifies the properties of
21 /// a section. A section is classified into the deepest possible
22 /// classification, and then the target maps them onto their sections based on
23 /// what capabilities they have.
24 ///
25 /// The comments below describe these as if they were an inheritance hierarchy
26 /// in order to explain the predicates below.
27 ///
28 class SectionKind {
29  enum Kind {
30  /// Metadata - Debug info sections or other metadata.
31  Metadata,
32 
33  /// Text - Text section, used for functions and other executable code.
34  Text,
35 
36  /// ReadOnly - Data that is never written to at program runtime by the
37  /// program or the dynamic linker. Things in the top-level readonly
38  /// SectionKind are not mergeable.
39  ReadOnly,
40 
41  /// MergableCString - Any null-terminated string which allows merging.
42  /// These values are known to end in a nul value of the specified size,
43  /// not otherwise contain a nul value, and be mergable. This allows the
44  /// linker to unique the strings if it so desires.
45 
46  /// Mergeable1ByteCString - 1 byte mergable, null terminated, string.
47  Mergeable1ByteCString,
48 
49  /// Mergeable2ByteCString - 2 byte mergable, null terminated, string.
50  Mergeable2ByteCString,
51 
52  /// Mergeable4ByteCString - 4 byte mergable, null terminated, string.
53  Mergeable4ByteCString,
54 
55  /// MergeableConst - These are sections for merging fixed-length
56  /// constants together. For example, this can be used to unique
57  /// constant pool entries etc.
58 
59  /// MergeableConst4 - This is a section used by 4-byte constants,
60  /// for example, floats.
61  MergeableConst4,
62 
63  /// MergeableConst8 - This is a section used by 8-byte constants,
64  /// for example, doubles.
65  MergeableConst8,
66 
67  /// MergeableConst16 - This is a section used by 16-byte constants,
68  /// for example, vectors.
69  MergeableConst16,
70 
71  /// Writeable - This is the base of all segments that need to be written
72  /// to during program runtime.
73 
74  /// ThreadLocal - This is the base of all TLS segments. All TLS
75  /// objects must be writeable, otherwise there is no reason for them to
76  /// be thread local!
77 
78  /// ThreadBSS - Zero-initialized TLS data objects.
79  ThreadBSS,
80 
81  /// ThreadData - Initialized TLS data objects.
82  ThreadData,
83 
84  /// GlobalWriteableData - Writeable data that is global (not thread
85  /// local).
86 
87  /// BSS - Zero initialized writeable data.
88  BSS,
89 
90  /// BSSLocal - This is BSS (zero initialized and writable) data
91  /// which has local linkage.
92  BSSLocal,
93 
94  /// BSSExtern - This is BSS data with normal external linkage.
95  BSSExtern,
96 
97  /// Common - Data with common linkage. These represent tentative
98  /// definitions, which always have a zero initializer and are never
99  /// marked 'constant'.
100  Common,
101 
102  /// DataRel - This is the most general form of data that is written
103  /// to by the program, it can have random relocations to arbitrary
104  /// globals.
105  DataRel,
106 
107  /// DataRelLocal - This is writeable data that has a non-zero
108  /// initializer and has relocations in it, but all of the
109  /// relocations are known to be within the final linked image
110  /// the global is linked into.
111  DataRelLocal,
112 
113  /// DataNoRel - This is writeable data that has a non-zero
114  /// initializer, but whose initializer is known to have no
115  /// relocations.
116  DataNoRel,
117 
118  /// ReadOnlyWithRel - These are global variables that are never
119  /// written to by the program, but that have relocations, so they
120  /// must be stuck in a writeable section so that the dynamic linker
121  /// can write to them. If it chooses to, the dynamic linker can
122  /// mark the pages these globals end up on as read-only after it is
123  /// done with its relocation phase.
124  ReadOnlyWithRel,
125 
126  /// ReadOnlyWithRelLocal - This is data that is readonly by the
127  /// program, but must be writeable so that the dynamic linker
128  /// can perform relocations in it. This is used when we know
129  /// that all the relocations are to globals in this final
130  /// linked image.
131  ReadOnlyWithRelLocal
132 
133  } K : 8;
134 public:
135 
136  bool isMetadata() const { return K == Metadata; }
137  bool isText() const { return K == Text; }
138 
139  bool isReadOnly() const {
140  return K == ReadOnly || isMergeableCString() ||
142  }
143 
144  bool isMergeableCString() const {
145  return K == Mergeable1ByteCString || K == Mergeable2ByteCString ||
146  K == Mergeable4ByteCString;
147  }
148  bool isMergeable1ByteCString() const { return K == Mergeable1ByteCString; }
149  bool isMergeable2ByteCString() const { return K == Mergeable2ByteCString; }
150  bool isMergeable4ByteCString() const { return K == Mergeable4ByteCString; }
151 
152  bool isMergeableConst() const {
153  return K == MergeableConst4 || K == MergeableConst8 ||
154  K == MergeableConst16;
155  }
156  bool isMergeableConst4() const { return K == MergeableConst4; }
157  bool isMergeableConst8() const { return K == MergeableConst8; }
158  bool isMergeableConst16() const { return K == MergeableConst16; }
159 
160  bool isWriteable() const {
161  return isThreadLocal() || isGlobalWriteableData();
162  }
163 
164  bool isThreadLocal() const {
165  return K == ThreadData || K == ThreadBSS;
166  }
167 
168  bool isThreadBSS() const { return K == ThreadBSS; }
169  bool isThreadData() const { return K == ThreadData; }
170 
171  bool isGlobalWriteableData() const {
172  return isBSS() || isCommon() || isDataRel() || isReadOnlyWithRel();
173  }
174 
175  bool isBSS() const { return K == BSS || K == BSSLocal || K == BSSExtern; }
176  bool isBSSLocal() const { return K == BSSLocal; }
177  bool isBSSExtern() const { return K == BSSExtern; }
178 
179  bool isCommon() const { return K == Common; }
180 
181  bool isDataRel() const {
182  return K == DataRel || K == DataRelLocal || K == DataNoRel;
183  }
184 
185  bool isDataRelLocal() const {
186  return K == DataRelLocal || K == DataNoRel;
187  }
188 
189  bool isDataNoRel() const { return K == DataNoRel; }
190 
191  bool isReadOnlyWithRel() const {
192  return K == ReadOnlyWithRel || K == ReadOnlyWithRelLocal;
193  }
194 
195  bool isReadOnlyWithRelLocal() const {
196  return K == ReadOnlyWithRelLocal;
197  }
198 private:
199  static SectionKind get(Kind K) {
200  SectionKind Res;
201  Res.K = K;
202  return Res;
203  }
204 public:
205 
206  static SectionKind getMetadata() { return get(Metadata); }
207  static SectionKind getText() { return get(Text); }
208  static SectionKind getReadOnly() { return get(ReadOnly); }
210  return get(Mergeable1ByteCString);
211  }
213  return get(Mergeable2ByteCString);
214  }
216  return get(Mergeable4ByteCString);
217  }
218  static SectionKind getMergeableConst4() { return get(MergeableConst4); }
219  static SectionKind getMergeableConst8() { return get(MergeableConst8); }
220  static SectionKind getMergeableConst16() { return get(MergeableConst16); }
221  static SectionKind getThreadBSS() { return get(ThreadBSS); }
222  static SectionKind getThreadData() { return get(ThreadData); }
223  static SectionKind getBSS() { return get(BSS); }
224  static SectionKind getBSSLocal() { return get(BSSLocal); }
225  static SectionKind getBSSExtern() { return get(BSSExtern); }
226  static SectionKind getCommon() { return get(Common); }
227  static SectionKind getDataRel() { return get(DataRel); }
228  static SectionKind getDataRelLocal() { return get(DataRelLocal); }
229  static SectionKind getDataNoRel() { return get(DataNoRel); }
230  static SectionKind getReadOnlyWithRel() { return get(ReadOnlyWithRel); }
232  return get(ReadOnlyWithRelLocal);
233  }
234 };
235 
236 } // end namespace llvm
237 
238 #endif
static SectionKind getReadOnlyWithRelLocal()
Definition: SectionKind.h:231
bool isMergeableConst() const
Definition: SectionKind.h:152
bool isBSSExtern() const
Definition: SectionKind.h:177
static SectionKind getDataRel()
Definition: SectionKind.h:227
bool isMergeable2ByteCString() const
Definition: SectionKind.h:149
bool isBSS() const
Definition: SectionKind.h:175
static SectionKind getDataRelLocal()
Definition: SectionKind.h:228
bool isReadOnlyWithRel() const
Definition: SectionKind.h:191
static SectionKind getMergeableConst8()
Definition: SectionKind.h:219
static SectionKind getMergeableConst16()
Definition: SectionKind.h:220
static SectionKind getMergeable1ByteCString()
Definition: SectionKind.h:209
static SectionKind getCommon()
Definition: SectionKind.h:226
static SectionKind getMergeableConst4()
Definition: SectionKind.h:218
bool isMergeableCString() const
Definition: SectionKind.h:144
static SectionKind getBSS()
Definition: SectionKind.h:223
static SectionKind getMergeable4ByteCString()
Definition: SectionKind.h:215
bool isWriteable() const
Definition: SectionKind.h:160
bool isMergeable4ByteCString() const
Definition: SectionKind.h:150
static SectionKind getThreadData()
Definition: SectionKind.h:222
bool isMergeableConst16() const
Definition: SectionKind.h:158
bool isDataNoRel() const
Definition: SectionKind.h:189
bool isMetadata() const
Definition: SectionKind.h:136
static SectionKind getBSSLocal()
Definition: SectionKind.h:224
bool isText() const
Definition: SectionKind.h:137
bool isThreadData() const
Definition: SectionKind.h:169
bool isMergeable1ByteCString() const
Definition: SectionKind.h:148
SectionKind - This is a simple POD value that classifies the properties of a section.
Definition: SectionKind.h:28
bool isBSSLocal() const
Definition: SectionKind.h:176
bool isThreadBSS() const
Definition: SectionKind.h:168
bool isThreadLocal() const
Definition: SectionKind.h:164
static SectionKind getThreadBSS()
Definition: SectionKind.h:221
bool isGlobalWriteableData() const
Definition: SectionKind.h:171
static SectionKind getDataNoRel()
Definition: SectionKind.h:229
static SectionKind getMetadata()
Definition: SectionKind.h:206
static SectionKind getReadOnlyWithRel()
Definition: SectionKind.h:230
bool isMergeableConst8() const
Definition: SectionKind.h:157
static SectionKind getMergeable2ByteCString()
Definition: SectionKind.h:212
static SectionKind getBSSExtern()
Definition: SectionKind.h:225
bool isCommon() const
Definition: SectionKind.h:179
bool isMergeableConst4() const
Definition: SectionKind.h:156
bool isReadOnlyWithRelLocal() const
Definition: SectionKind.h:195
bool isDataRel() const
Definition: SectionKind.h:181
static SectionKind getReadOnly()
Definition: SectionKind.h:208
Root of the metadata hierarchy.
Definition: Metadata.h:45
bool isDataRelLocal() const
Definition: SectionKind.h:185
bool isReadOnly() const
Definition: SectionKind.h:139
static SectionKind getText()
Definition: SectionKind.h:207