src/llvm/include/llvm/MC/SectionKind.h

   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         MergeableConst,
  59
  60             /// MergeableConst4 - This is a section used by 4-byte constants,
  61             /// for example, floats.
  62             MergeableConst4,
  63
  64             /// MergeableConst8 - This is a section used by 8-byte constants,
  65             /// for example, doubles.
  66             MergeableConst8,
  67
  68             /// MergeableConst16 - This is a section used by 16-byte constants,
  69             /// for example, vectors.
  70             MergeableConst16,
  71
  72     /// Writeable - This is the base of all segments that need to be written
  73     /// to during program runtime.
  74
  75        /// ThreadLocal - This is the base of all TLS segments.  All TLS
  76        /// objects must be writeable, otherwise there is no reason for them to
  77        /// be thread local!
  78
  79            /// ThreadBSS - Zero-initialized TLS data objects.
  80            ThreadBSS,
  81
  82            /// ThreadData - Initialized TLS data objects.
  83            ThreadData,
  84
  85        /// GlobalWriteableData - Writeable data that is global (not thread
  86        /// local).
  87
  88            /// BSS - Zero initialized writeable data.
  89            BSS,
  90
  91                /// BSSLocal - This is BSS (zero initialized and writable) data
  92                /// which has local linkage.
  93                BSSLocal,
  94
  95                /// BSSExtern - This is BSS data with normal external linkage.
  96                BSSExtern,
  97
  98            /// Common - Data with common linkage.  These represent tentative
  99            /// definitions, which always have a zero initializer and are never
 100            /// marked 'constant'.
 101            Common,
 102
 103            /// DataRel - This is the most general form of data that is written
 104            /// to by the program, it can have random relocations to arbitrary
 105            /// globals.
 106            DataRel,
 107
 108                /// DataRelLocal - This is writeable data that has a non-zero
 109                /// initializer and has relocations in it, but all of the
 110                /// relocations are known to be within the final linked image
 111                /// the global is linked into.
 112                DataRelLocal,
 113
 114                    /// DataNoRel - This is writeable data that has a non-zero
 115                    /// initializer, but whose initializer is known to have no
 116                    /// relocations.
 117                    DataNoRel,
 118
 119            /// ReadOnlyWithRel - These are global variables that are never
 120            /// written to by the program, but that have relocations, so they
 121            /// must be stuck in a writeable section so that the dynamic linker
 122            /// can write to them.  If it chooses to, the dynamic linker can
 123            /// mark the pages these globals end up on as read-only after it is
 124            /// done with its relocation phase.
 125            ReadOnlyWithRel,
 126
 127                /// ReadOnlyWithRelLocal - This is data that is readonly by the
 128                /// program, but must be writeable so that the dynamic linker
 129                /// can perform relocations in it.  This is used when we know
 130                /// that all the relocations are to globals in this final
 131                /// linked image.
 132                ReadOnlyWithRelLocal
 133
 134   } K : 8;
 135 public:
 136
 137   bool isMetadata() const { return K == Metadata; }
 138   bool isText() const { return K == Text; }
 139
 140   bool isReadOnly() const {
 141     return K == ReadOnly || isMergeableCString() ||
 142            isMergeableConst();
 143   }
 144
 145   bool isMergeableCString() const {
 146     return K == Mergeable1ByteCString || K == Mergeable2ByteCString ||
 147            K == Mergeable4ByteCString;
 148   }
 149   bool isMergeable1ByteCString() const { return K == Mergeable1ByteCString; }
 150   bool isMergeable2ByteCString() const { return K == Mergeable2ByteCString; }
 151   bool isMergeable4ByteCString() const { return K == Mergeable4ByteCString; }
 152
 153   bool isMergeableConst() const {
 154     return K == MergeableConst || K == MergeableConst4 ||
 155            K == MergeableConst8 || K == MergeableConst16;
 156   }
 157   bool isMergeableConst4() const { return K == MergeableConst4; }
 158   bool isMergeableConst8() const { return K == MergeableConst8; }
 159   bool isMergeableConst16() const { return K == MergeableConst16; }
 160
 161   bool isWriteable() const {
 162     return isThreadLocal() || isGlobalWriteableData();
 163   }
 164
 165   bool isThreadLocal() const {
 166     return K == ThreadData || K == ThreadBSS;
 167   }
 168
 169   bool isThreadBSS() const { return K == ThreadBSS; }
 170   bool isThreadData() const { return K == ThreadData; }
 171
 172   bool isGlobalWriteableData() const {
 173     return isBSS() || isCommon() || isDataRel() || isReadOnlyWithRel();
 174   }
 175
 176   bool isBSS() const { return K == BSS || K == BSSLocal || K == BSSExtern; }
 177   bool isBSSLocal() const { return K == BSSLocal; }
 178   bool isBSSExtern() const { return K == BSSExtern; }
 179
 180   bool isCommon() const { return K == Common; }
 181
 182   bool isDataRel() const {
 183     return K == DataRel || K == DataRelLocal || K == DataNoRel;
 184   }
 185
 186   bool isDataRelLocal() const {
 187     return K == DataRelLocal || K == DataNoRel;
 188   }
 189
 190   bool isDataNoRel() const { return K == DataNoRel; }
 191
 192   bool isReadOnlyWithRel() const {
 193     return K == ReadOnlyWithRel || K == ReadOnlyWithRelLocal;
 194   }
 195
 196   bool isReadOnlyWithRelLocal() const {
 197     return K == ReadOnlyWithRelLocal;
 198   }
 199 private:
 200   static SectionKind get(Kind K) {
 201     SectionKind Res;
 202     Res.K = K;
 203     return Res;
 204   }
 205 public:
 206
 207   static SectionKind getMetadata() { return get(Metadata); }
 208   static SectionKind getText() { return get(Text); }
 209   static SectionKind getReadOnly() { return get(ReadOnly); }
 210   static SectionKind getMergeable1ByteCString() {
 211     return get(Mergeable1ByteCString);
 212   }
 213   static SectionKind getMergeable2ByteCString() {
 214     return get(Mergeable2ByteCString);
 215   }
 216   static SectionKind getMergeable4ByteCString() {
 217     return get(Mergeable4ByteCString);
 218   }
 219   static SectionKind getMergeableConst() { return get(MergeableConst); }
 220   static SectionKind getMergeableConst4() { return get(MergeableConst4); }
 221   static SectionKind getMergeableConst8() { return get(MergeableConst8); }
 222   static SectionKind getMergeableConst16() { return get(MergeableConst16); }
 223   static SectionKind getThreadBSS() { return get(ThreadBSS); }
 224   static SectionKind getThreadData() { return get(ThreadData); }
 225   static SectionKind getBSS() { return get(BSS); }
 226   static SectionKind getBSSLocal() { return get(BSSLocal); }
 227   static SectionKind getBSSExtern() { return get(BSSExtern); }
 228   static SectionKind getCommon() { return get(Common); }
 229   static SectionKind getDataRel() { return get(DataRel); }
 230   static SectionKind getDataRelLocal() { return get(DataRelLocal); }
 231   static SectionKind getDataNoRel() { return get(DataNoRel); }
 232   static SectionKind getReadOnlyWithRel() { return get(ReadOnlyWithRel); }
 233   static SectionKind getReadOnlyWithRelLocal(){
 234     return get(ReadOnlyWithRelLocal);
 235   }
 236 };
 237
 238 } // end namespace llvm
 239
 240 #endif