1 //===-- llvm/MC/SectionKind.h - Classification of sections ------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #ifndef LLVM_MC_SECTIONKIND_H 10 #define LLVM_MC_SECTIONKIND_H 11 12 namespace llvm { 13 14 /// SectionKind - This is a simple POD value that classifies the properties of 15 /// a section. A section is classified into the deepest possible 16 /// classification, and then the target maps them onto their sections based on 17 /// what capabilities they have. 18 /// 19 /// The comments below describe these as if they were an inheritance hierarchy 20 /// in order to explain the predicates below. 21 /// 22 class SectionKind { 23 enum Kind { 24 /// Metadata - Debug info sections or other metadata. 25 Metadata, 26 27 /// Text - Text section, used for functions and other executable code. 28 Text, 29 30 /// ExecuteOnly, Text section that is not readable. 31 ExecuteOnly, 32 33 /// ReadOnly - Data that is never written to at program runtime by the 34 /// program or the dynamic linker. Things in the top-level readonly 35 /// SectionKind are not mergeable. 36 ReadOnly, 37 38 /// MergableCString - Any null-terminated string which allows merging. 39 /// These values are known to end in a nul value of the specified size, 40 /// not otherwise contain a nul value, and be mergable. This allows the 41 /// linker to unique the strings if it so desires. 42 43 /// Mergeable1ByteCString - 1 byte mergable, null terminated, string. 44 Mergeable1ByteCString, 45 46 /// Mergeable2ByteCString - 2 byte mergable, null terminated, string. 47 Mergeable2ByteCString, 48 49 /// Mergeable4ByteCString - 4 byte mergable, null terminated, string. 50 Mergeable4ByteCString, 51 52 /// MergeableConst - These are sections for merging fixed-length 53 /// constants together. For example, this can be used to unique 54 /// constant pool entries etc. 55 56 /// MergeableConst4 - This is a section used by 4-byte constants, 57 /// for example, floats. 58 MergeableConst4, 59 60 /// MergeableConst8 - This is a section used by 8-byte constants, 61 /// for example, doubles. 62 MergeableConst8, 63 64 /// MergeableConst16 - This is a section used by 16-byte constants, 65 /// for example, vectors. 66 MergeableConst16, 67 68 /// MergeableConst32 - This is a section used by 32-byte constants, 69 /// for example, vectors. 70 MergeableConst32, 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 /// ThreadBSSLocal - Zero-initialized TLS data objects with local linkage. 86 ThreadBSSLocal, 87 88 /// GlobalWriteableData - Writeable data that is global (not thread 89 /// local). 90 91 /// BSS - Zero initialized writeable data. 92 BSS, 93 94 /// BSSLocal - This is BSS (zero initialized and writable) data 95 /// which has local linkage. 96 BSSLocal, 97 98 /// BSSExtern - This is BSS data with normal external linkage. 99 BSSExtern, 100 101 /// Common - Data with common linkage. These represent tentative 102 /// definitions, which always have a zero initializer and are never 103 /// marked 'constant'. 104 Common, 105 106 /// This is writeable data that has a non-zero initializer. 107 Data, 108 109 /// ReadOnlyWithRel - These are global variables that are never 110 /// written to by the program, but that have relocations, so they 111 /// must be stuck in a writeable section so that the dynamic linker 112 /// can write to them. If it chooses to, the dynamic linker can 113 /// mark the pages these globals end up on as read-only after it is 114 /// done with its relocation phase. 115 ReadOnlyWithRel 116 } K : 8; 117 public: 118 119 bool isMetadata() const { return K == Metadata; } 120 121 bool isText() const { return K == Text || K == ExecuteOnly; } 122 123 bool isExecuteOnly() const { return K == ExecuteOnly; } 124 125 bool isReadOnly() const { 126 return K == ReadOnly || isMergeableCString() || 127 isMergeableConst(); 128 } 129 130 bool isMergeableCString() const { 131 return K == Mergeable1ByteCString || K == Mergeable2ByteCString || 132 K == Mergeable4ByteCString; 133 } 134 bool isMergeable1ByteCString() const { return K == Mergeable1ByteCString; } 135 bool isMergeable2ByteCString() const { return K == Mergeable2ByteCString; } 136 bool isMergeable4ByteCString() const { return K == Mergeable4ByteCString; } 137 138 bool isMergeableConst() const { 139 return K == MergeableConst4 || K == MergeableConst8 || 140 K == MergeableConst16 || K == MergeableConst32; 141 } 142 bool isMergeableConst4() const { return K == MergeableConst4; } 143 bool isMergeableConst8() const { return K == MergeableConst8; } 144 bool isMergeableConst16() const { return K == MergeableConst16; } 145 bool isMergeableConst32() const { return K == MergeableConst32; } 146 147 bool isWriteable() const { 148 return isThreadLocal() || isGlobalWriteableData(); 149 } 150 151 bool isThreadLocal() const { 152 return K == ThreadData || K == ThreadBSS || K == ThreadBSSLocal; 153 } 154 155 bool isThreadBSS() const { return K == ThreadBSS || K == ThreadBSSLocal; } 156 bool isThreadData() const { return K == ThreadData; } 157 bool isThreadBSSLocal() const { return K == ThreadBSSLocal; } 158 159 bool isGlobalWriteableData() const { 160 return isBSS() || isCommon() || isData() || isReadOnlyWithRel(); 161 } 162 163 bool isBSS() const { return K == BSS || K == BSSLocal || K == BSSExtern; } 164 bool isBSSLocal() const { return K == BSSLocal; } 165 bool isBSSExtern() const { return K == BSSExtern; } 166 167 bool isCommon() const { return K == Common; } 168 169 bool isData() const { return K == Data; } 170 171 bool isReadOnlyWithRel() const { 172 return K == ReadOnlyWithRel; 173 } 174 private: 175 static SectionKind get(Kind K) { 176 SectionKind Res; 177 Res.K = K; 178 return Res; 179 } 180 public: 181 182 static SectionKind getMetadata() { return get(Metadata); } 183 static SectionKind getText() { return get(Text); } 184 static SectionKind getExecuteOnly() { return get(ExecuteOnly); } 185 static SectionKind getReadOnly() { return get(ReadOnly); } 186 static SectionKind getMergeable1ByteCString() { 187 return get(Mergeable1ByteCString); 188 } 189 static SectionKind getMergeable2ByteCString() { 190 return get(Mergeable2ByteCString); 191 } 192 static SectionKind getMergeable4ByteCString() { 193 return get(Mergeable4ByteCString); 194 } 195 static SectionKind getMergeableConst4() { return get(MergeableConst4); } 196 static SectionKind getMergeableConst8() { return get(MergeableConst8); } 197 static SectionKind getMergeableConst16() { return get(MergeableConst16); } 198 static SectionKind getMergeableConst32() { return get(MergeableConst32); } 199 static SectionKind getThreadBSS() { return get(ThreadBSS); } 200 static SectionKind getThreadData() { return get(ThreadData); } 201 static SectionKind getThreadBSSLocal() { return get(ThreadBSSLocal); } 202 static SectionKind getBSS() { return get(BSS); } 203 static SectionKind getBSSLocal() { return get(BSSLocal); } 204 static SectionKind getBSSExtern() { return get(BSSExtern); } 205 static SectionKind getCommon() { return get(Common); } 206 static SectionKind getData() { return get(Data); } 207 static SectionKind getReadOnlyWithRel() { return get(ReadOnlyWithRel); } 208 }; 209 210 } // end namespace llvm 211 212 #endif 213
Indexes created Tue Feb 24 08:35:24 UTC 2026