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/Triple.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 <cassert>
17
18 using namespace llvm;
19
20 // Decides whether a '.section' directive
21 // should be printed before the section name.
ShouldOmitSectionDirective(StringRef Name,const MCAsmInfo & MAI) const22 bool MCSectionELF::ShouldOmitSectionDirective(StringRef Name,
23 const MCAsmInfo &MAI) const {
24 if (isUnique())
25 return false;
26
27 return MAI.shouldOmitSectionDirective(Name);
28 }
29
printName(raw_ostream & OS,StringRef Name)30 static void printName(raw_ostream &OS, StringRef Name) {
31 if (Name.find_first_not_of("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
PrintSwitchToSection(const MCAsmInfo & MAI,const Triple & T,raw_ostream & OS,const MCExpr * Subsection) const53 void MCSectionELF::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
54 raw_ostream &OS,
55 const MCExpr *Subsection) const {
56 if (ShouldOmitSectionDirective(getName(), MAI)) {
57 OS << '\t' << getName();
58 if (Subsection) {
59 OS << '\t';
60 Subsection->print(OS, &MAI);
61 }
62 OS << '\n';
63 return;
64 }
65
66 OS << "\t.section\t";
67 printName(OS, 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_GROUP)
94 OS << 'G';
95 if (Flags & ELF::SHF_WRITE)
96 OS << 'w';
97 if (Flags & ELF::SHF_MERGE)
98 OS << 'M';
99 if (Flags & ELF::SHF_STRINGS)
100 OS << 'S';
101 if (Flags & ELF::SHF_TLS)
102 OS << 'T';
103 if (Flags & ELF::SHF_LINK_ORDER)
104 OS << 'o';
105 if (Flags & ELF::SHF_GNU_RETAIN)
106 OS << 'R';
107
108 // If there are target-specific flags, print them.
109 Triple::ArchType Arch = T.getArch();
110 if (Arch == Triple::xcore) {
111 if (Flags & ELF::XCORE_SHF_CP_SECTION)
112 OS << 'c';
113 if (Flags & ELF::XCORE_SHF_DP_SECTION)
114 OS << 'd';
115 } else if (T.isARM() || T.isThumb()) {
116 if (Flags & ELF::SHF_ARM_PURECODE)
117 OS << 'y';
118 } else if (Arch == Triple::hexagon) {
119 if (Flags & ELF::SHF_HEX_GPREL)
120 OS << 's';
121 }
122
123 OS << '"';
124
125 OS << ',';
126
127 // If comment string is '@', e.g. as on ARM - use '%' instead
128 if (MAI.getCommentString()[0] == '@')
129 OS << '%';
130 else
131 OS << '@';
132
133 if (Type == ELF::SHT_INIT_ARRAY)
134 OS << "init_array";
135 else if (Type == ELF::SHT_FINI_ARRAY)
136 OS << "fini_array";
137 else if (Type == ELF::SHT_PREINIT_ARRAY)
138 OS << "preinit_array";
139 else if (Type == ELF::SHT_NOBITS)
140 OS << "nobits";
141 else if (Type == ELF::SHT_NOTE)
142 OS << "note";
143 else if (Type == ELF::SHT_PROGBITS)
144 OS << "progbits";
145 else if (Type == ELF::SHT_X86_64_UNWIND)
146 OS << "unwind";
147 else if (Type == ELF::SHT_MIPS_DWARF)
148 // Print hex value of the flag while we do not have
149 // any standard symbolic representation of the flag.
150 OS << "0x7000001e";
151 else if (Type == ELF::SHT_LLVM_ODRTAB)
152 OS << "llvm_odrtab";
153 else if (Type == ELF::SHT_LLVM_LINKER_OPTIONS)
154 OS << "llvm_linker_options";
155 else if (Type == ELF::SHT_LLVM_CALL_GRAPH_PROFILE)
156 OS << "llvm_call_graph_profile";
157 else if (Type == ELF::SHT_LLVM_DEPENDENT_LIBRARIES)
158 OS << "llvm_dependent_libraries";
159 else if (Type == ELF::SHT_LLVM_SYMPART)
160 OS << "llvm_sympart";
161 else if (Type == ELF::SHT_LLVM_BB_ADDR_MAP)
162 OS << "llvm_bb_addr_map";
163 else
164 report_fatal_error("unsupported type 0x" + Twine::utohexstr(Type) +
165 " for section " + getName());
166
167 if (EntrySize) {
168 assert(Flags & ELF::SHF_MERGE);
169 OS << "," << EntrySize;
170 }
171
172 if (Flags & ELF::SHF_GROUP) {
173 OS << ",";
174 printName(OS, Group.getPointer()->getName());
175 if (isComdat())
176 OS << ",comdat";
177 }
178
179 if (Flags & ELF::SHF_LINK_ORDER) {
180 OS << ",";
181 if (LinkedToSym)
182 printName(OS, LinkedToSym->getName());
183 else
184 OS << '0';
185 }
186
187 if (isUnique())
188 OS << ",unique," << UniqueID;
189
190 OS << '\n';
191
192 if (Subsection) {
193 OS << "\t.subsection\t";
194 Subsection->print(OS, &MAI);
195 OS << '\n';
196 }
197 }
198
UseCodeAlign() const199 bool MCSectionELF::UseCodeAlign() const {
200 return getFlags() & ELF::SHF_EXECINSTR;
201 }
202
isVirtualSection() const203 bool MCSectionELF::isVirtualSection() const {
204 return getType() == ELF::SHT_NOBITS;
205 }
206
getVirtualSectionKind() const207 StringRef MCSectionELF::getVirtualSectionKind() const { return "SHT_NOBITS"; }
208