1//===- lib/MC/MCSectionELF.cpp - ELF Code Section Representation ----------===//
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#include "llvm/MC/MCSectionELF.h"
10#include "llvm/BinaryFormat/ELF.h"
11#include "llvm/MC/MCAsmInfo.h"
12#include "llvm/MC/MCExpr.h"
13#include "llvm/Support/ErrorHandling.h"
14#include "llvm/Support/raw_ostream.h"
15#include "llvm/TargetParser/Triple.h"
16#include <cassert>
17
18using namespace llvm;
19
20// Decides whether a '.section' directive
21// should be printed before the section name.
22bool MCSectionELF::shouldOmitSectionDirective(StringRef Name,
23 const MCAsmInfo &MAI) const {
24 if (isUnique())
25 return false;
26
27 return MAI.shouldOmitSectionDirective(SectionName: Name);
28}
29
30static void printName(raw_ostream &OS, StringRef Name) {
31 if (Name.find_first_not_of(Chars: "0123456789_."
32 "abcdefghijklmnopqrstuvwxyz"
33 "ABCDEFGHIJKLMNOPQRSTUVWXYZ") == Name.npos) {
34 OS << Name;
35 return;
36 }
37 OS << '"';
38 for (const char *B = Name.begin(), *E = Name.end(); B < E; ++B) {
39 if (*B == '"') // Unquoted "
40 OS << "\\\"";
41 else if (*B != '\\') // Neither " or backslash
42 OS << *B;
43 else if (B + 1 == E) // Trailing backslash
44 OS << "\\\\";
45 else {
46 OS << B[0] << B[1]; // Quoted character
47 ++B;
48 }
49 }
50 OS << '"';
51}
52
53void MCSectionELF::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
54 raw_ostream &OS,
55 const MCExpr *Subsection) const {
56 if (shouldOmitSectionDirective(Name: getName(), MAI)) {
57 OS << '\t' << getName();
58 if (Subsection) {
59 OS << '\t';
60 Subsection->print(OS, MAI: &MAI);
61 }
62 OS << '\n';
63 return;
64 }
65
66 OS << "\t.section\t";
67 printName(OS, Name: getName());
68
69 // Handle the weird solaris syntax if desired.
70 if (MAI.usesSunStyleELFSectionSwitchSyntax() &&
71 !(Flags & ELF::SHF_MERGE)) {
72 if (Flags & ELF::SHF_ALLOC)
73 OS << ",#alloc";
74 if (Flags & ELF::SHF_EXECINSTR)
75 OS << ",#execinstr";
76 if (Flags & ELF::SHF_WRITE)
77 OS << ",#write";
78 if (Flags & ELF::SHF_EXCLUDE)
79 OS << ",#exclude";
80 if (Flags & ELF::SHF_TLS)
81 OS << ",#tls";
82 OS << '\n';
83 return;
84 }
85
86 OS << ",\"";
87 if (Flags & ELF::SHF_ALLOC)
88 OS << 'a';
89 if (Flags & ELF::SHF_EXCLUDE)
90 OS << 'e';
91 if (Flags & ELF::SHF_EXECINSTR)
92 OS << 'x';
93 if (Flags & ELF::SHF_WRITE)
94 OS << 'w';
95 if (Flags & ELF::SHF_MERGE)
96 OS << 'M';
97 if (Flags & ELF::SHF_STRINGS)
98 OS << 'S';
99 if (Flags & ELF::SHF_TLS)
100 OS << 'T';
101 if (Flags & ELF::SHF_LINK_ORDER)
102 OS << 'o';
103 if (Flags & ELF::SHF_GROUP)
104 OS << 'G';
105 if (Flags & ELF::SHF_GNU_RETAIN)
106 OS << 'R';
107
108 // If there are os-specific flags, print them.
109 if (T.isOSSolaris())
110 if (Flags & ELF::SHF_SUNW_NODISCARD)
111 OS << 'R';
112
113 // If there are target-specific flags, print them.
114 Triple::ArchType Arch = T.getArch();
115 if (Arch == Triple::xcore) {
116 if (Flags & ELF::XCORE_SHF_CP_SECTION)
117 OS << 'c';
118 if (Flags & ELF::XCORE_SHF_DP_SECTION)
119 OS << 'd';
120 } else if (T.isARM() || T.isThumb()) {
121 if (Flags & ELF::SHF_ARM_PURECODE)
122 OS << 'y';
123 } else if (Arch == Triple::hexagon) {
124 if (Flags & ELF::SHF_HEX_GPREL)
125 OS << 's';
126 } else if (Arch == Triple::x86_64) {
127 if (Flags & ELF::SHF_X86_64_LARGE)
128 OS << 'l';
129 }
130
131 OS << '"';
132
133 OS << ',';
134
135 // If comment string is '@', e.g. as on ARM - use '%' instead
136 if (MAI.getCommentString()[0] == '@')
137 OS << '%';
138 else
139 OS << '@';
140
141 if (Type == ELF::SHT_INIT_ARRAY)
142 OS << "init_array";
143 else if (Type == ELF::SHT_FINI_ARRAY)
144 OS << "fini_array";
145 else if (Type == ELF::SHT_PREINIT_ARRAY)
146 OS << "preinit_array";
147 else if (Type == ELF::SHT_NOBITS)
148 OS << "nobits";
149 else if (Type == ELF::SHT_NOTE)
150 OS << "note";
151 else if (Type == ELF::SHT_PROGBITS)
152 OS << "progbits";
153 else if (Type == ELF::SHT_X86_64_UNWIND)
154 OS << "unwind";
155 else if (Type == ELF::SHT_MIPS_DWARF)
156 // Print hex value of the flag while we do not have
157 // any standard symbolic representation of the flag.
158 OS << "0x7000001e";
159 else if (Type == ELF::SHT_LLVM_ODRTAB)
160 OS << "llvm_odrtab";
161 else if (Type == ELF::SHT_LLVM_LINKER_OPTIONS)
162 OS << "llvm_linker_options";
163 else if (Type == ELF::SHT_LLVM_CALL_GRAPH_PROFILE)
164 OS << "llvm_call_graph_profile";
165 else if (Type == ELF::SHT_LLVM_DEPENDENT_LIBRARIES)
166 OS << "llvm_dependent_libraries";
167 else if (Type == ELF::SHT_LLVM_SYMPART)
168 OS << "llvm_sympart";
169 else if (Type == ELF::SHT_LLVM_BB_ADDR_MAP)
170 OS << "llvm_bb_addr_map";
171 else if (Type == ELF::SHT_LLVM_BB_ADDR_MAP_V0)
172 OS << "llvm_bb_addr_map_v0";
173 else if (Type == ELF::SHT_LLVM_OFFLOADING)
174 OS << "llvm_offloading";
175 else if (Type == ELF::SHT_LLVM_LTO)
176 OS << "llvm_lto";
177 else
178 report_fatal_error(reason: "unsupported type 0x" + Twine::utohexstr(Val: Type) +
179 " for section " + getName());
180
181 if (EntrySize) {
182 assert(Flags & ELF::SHF_MERGE);
183 OS << "," << EntrySize;
184 }
185
186 if (Flags & ELF::SHF_LINK_ORDER) {
187 OS << ",";
188 if (LinkedToSym)
189 printName(OS, Name: LinkedToSym->getName());
190 else
191 OS << '0';
192 }
193
194 if (Flags & ELF::SHF_GROUP) {
195 OS << ",";
196 printName(OS, Name: Group.getPointer()->getName());
197 if (isComdat())
198 OS << ",comdat";
199 }
200
201 if (isUnique())
202 OS << ",unique," << UniqueID;
203
204 OS << '\n';
205
206 if (Subsection) {
207 OS << "\t.subsection\t";
208 Subsection->print(OS, MAI: &MAI);
209 OS << '\n';
210 }
211}
212
213bool MCSectionELF::useCodeAlign() const {
214 return getFlags() & ELF::SHF_EXECINSTR;
215}
216
217bool MCSectionELF::isVirtualSection() const {
218 return getType() == ELF::SHT_NOBITS;
219}
220
221StringRef MCSectionELF::getVirtualSectionKind() const { return "SHT_NOBITS"; }
222

source code of llvm/lib/MC/MCSectionELF.cpp