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/ADT/Twine.h"
11#include "llvm/BinaryFormat/ELF.h"
12#include "llvm/MC/MCAsmInfo.h"
13#include "llvm/MC/MCExpr.h"
14#include "llvm/Support/ErrorHandling.h"
15#include "llvm/Support/raw_ostream.h"
16#include "llvm/TargetParser/Triple.h"
17#include <cassert>
18
19using namespace llvm;
20
21// Decides whether a '.section' directive
22// should be printed before the section name.
23bool MCSectionELF::shouldOmitSectionDirective(StringRef Name,
24 const MCAsmInfo &MAI) const {
25 if (isUnique())
26 return false;
27
28 return MAI.shouldOmitSectionDirective(SectionName: Name);
29}
30
31static void printName(raw_ostream &OS, StringRef Name) {
32 if (Name.find_first_not_of(Chars: "0123456789_."
33 "abcdefghijklmnopqrstuvwxyz"
34 "ABCDEFGHIJKLMNOPQRSTUVWXYZ") == Name.npos) {
35 OS << Name;
36 return;
37 }
38 OS << '"';
39 for (const char *B = Name.begin(), *E = Name.end(); B < E; ++B) {
40 if (*B == '"') // Unquoted "
41 OS << "\\\"";
42 else if (*B != '\\') // Neither " or backslash
43 OS << *B;
44 else if (B + 1 == E) // Trailing backslash
45 OS << "\\\\";
46 else {
47 OS << B[0] << B[1]; // Quoted character
48 ++B;
49 }
50 }
51 OS << '"';
52}
53
54void MCSectionELF::printSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
55 raw_ostream &OS,
56 uint32_t Subsection) const {
57 if (shouldOmitSectionDirective(Name: getName(), MAI)) {
58 OS << '\t' << getName();
59 if (Subsection)
60 OS << '\t' << Subsection;
61 OS << '\n';
62 return;
63 }
64
65 OS << "\t.section\t";
66 printName(OS, Name: getName());
67
68 // Handle the weird solaris syntax if desired.
69 if (MAI.usesSunStyleELFSectionSwitchSyntax() &&
70 !(Flags & ELF::SHF_MERGE)) {
71 if (Flags & ELF::SHF_ALLOC)
72 OS << ",#alloc";
73 if (Flags & ELF::SHF_EXECINSTR)
74 OS << ",#execinstr";
75 if (Flags & ELF::SHF_WRITE)
76 OS << ",#write";
77 if (Flags & ELF::SHF_EXCLUDE)
78 OS << ",#exclude";
79 if (Flags & ELF::SHF_TLS)
80 OS << ",#tls";
81 OS << '\n';
82 return;
83 }
84
85 OS << ",\"";
86 if (Flags & ELF::SHF_ALLOC)
87 OS << 'a';
88 if (Flags & ELF::SHF_EXCLUDE)
89 OS << 'e';
90 if (Flags & ELF::SHF_EXECINSTR)
91 OS << 'x';
92 if (Flags & ELF::SHF_WRITE)
93 OS << 'w';
94 if (Flags & ELF::SHF_MERGE)
95 OS << 'M';
96 if (Flags & ELF::SHF_STRINGS)
97 OS << 'S';
98 if (Flags & ELF::SHF_TLS)
99 OS << 'T';
100 if (Flags & ELF::SHF_LINK_ORDER)
101 OS << 'o';
102 if (Flags & ELF::SHF_GROUP)
103 OS << 'G';
104 if (Flags & ELF::SHF_GNU_RETAIN)
105 OS << 'R';
106
107 // If there are os-specific flags, print them.
108 if (T.isOSSolaris())
109 if (Flags & ELF::SHF_SUNW_NODISCARD)
110 OS << 'R';
111
112 // If there are target-specific flags, print them.
113 Triple::ArchType Arch = T.getArch();
114 if (Arch == Triple::xcore) {
115 if (Flags & ELF::XCORE_SHF_CP_SECTION)
116 OS << 'c';
117 if (Flags & ELF::XCORE_SHF_DP_SECTION)
118 OS << 'd';
119 } else if (T.isARM() || T.isThumb()) {
120 if (Flags & ELF::SHF_ARM_PURECODE)
121 OS << 'y';
122 } else if (T.isAArch64()) {
123 if (Flags & ELF::SHF_AARCH64_PURECODE)
124 OS << 'y';
125 } else if (Arch == Triple::hexagon) {
126 if (Flags & ELF::SHF_HEX_GPREL)
127 OS << 's';
128 } else if (Arch == Triple::x86_64) {
129 if (Flags & ELF::SHF_X86_64_LARGE)
130 OS << 'l';
131 }
132
133 OS << '"';
134
135 OS << ',';
136
137 // If comment string is '@', e.g. as on ARM - use '%' instead
138 if (MAI.getCommentString()[0] == '@')
139 OS << '%';
140 else
141 OS << '@';
142
143 if (Type == ELF::SHT_INIT_ARRAY)
144 OS << "init_array";
145 else if (Type == ELF::SHT_FINI_ARRAY)
146 OS << "fini_array";
147 else if (Type == ELF::SHT_PREINIT_ARRAY)
148 OS << "preinit_array";
149 else if (Type == ELF::SHT_NOBITS)
150 OS << "nobits";
151 else if (Type == ELF::SHT_NOTE)
152 OS << "note";
153 else if (Type == ELF::SHT_PROGBITS)
154 OS << "progbits";
155 else if (Type == ELF::SHT_X86_64_UNWIND)
156 OS << "unwind";
157 else if (Type == ELF::SHT_MIPS_DWARF)
158 // Print hex value of the flag while we do not have
159 // any standard symbolic representation of the flag.
160 OS << "0x7000001e";
161 else if (Type == ELF::SHT_LLVM_ODRTAB)
162 OS << "llvm_odrtab";
163 else if (Type == ELF::SHT_LLVM_LINKER_OPTIONS)
164 OS << "llvm_linker_options";
165 else if (Type == ELF::SHT_LLVM_CALL_GRAPH_PROFILE)
166 OS << "llvm_call_graph_profile";
167 else if (Type == ELF::SHT_LLVM_DEPENDENT_LIBRARIES)
168 OS << "llvm_dependent_libraries";
169 else if (Type == ELF::SHT_LLVM_SYMPART)
170 OS << "llvm_sympart";
171 else if (Type == ELF::SHT_LLVM_BB_ADDR_MAP)
172 OS << "llvm_bb_addr_map";
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 if (Type == ELF::SHT_LLVM_JT_SIZES)
178 OS << "llvm_jt_sizes";
179 else
180 OS << "0x" << Twine::utohexstr(Val: Type);
181
182 if (EntrySize) {
183 assert(Flags & ELF::SHF_MERGE);
184 OS << "," << EntrySize;
185 }
186
187 if (Flags & ELF::SHF_LINK_ORDER) {
188 OS << ",";
189 if (LinkedToSym)
190 printName(OS, Name: LinkedToSym->getName());
191 else
192 OS << '0';
193 }
194
195 if (Flags & ELF::SHF_GROUP) {
196 OS << ",";
197 printName(OS, Name: Group.getPointer()->getName());
198 if (isComdat())
199 OS << ",comdat";
200 }
201
202 if (isUnique())
203 OS << ",unique," << UniqueID;
204
205 OS << '\n';
206
207 if (Subsection) {
208 OS << "\t.subsection\t" << Subsection;
209 OS << '\n';
210 }
211}
212
213bool MCSectionELF::useCodeAlign() const {
214 return getFlags() & ELF::SHF_EXECINSTR;
215}
216
217StringRef MCSectionELF::getVirtualSectionKind() const { return "SHT_NOBITS"; }
218