1 //===- lib/MC/MCSectionELF.cpp - ELF Code Section Representation ----------===//
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 #include "llvm/MC/MCSectionELF.h"
11 #include "llvm/ADT/Triple.h"
12 #include "llvm/BinaryFormat/ELF.h"
13 #include "llvm/MC/MCAsmInfo.h"
14 #include "llvm/MC/MCExpr.h"
15 #include "llvm/Support/ErrorHandling.h"
16 #include "llvm/Support/raw_ostream.h"
17 #include <cassert>
18
19 using namespace llvm;
20
21 MCSectionELF::~MCSectionELF() = default; // anchor.
22
23 // Decides whether a '.section' directive
24 // should be printed before the section name.
ShouldOmitSectionDirective(StringRef Name,const MCAsmInfo & MAI) const25 bool MCSectionELF::ShouldOmitSectionDirective(StringRef Name,
26 const MCAsmInfo &MAI) const {
27 if (isUnique())
28 return false;
29
30 return MAI.shouldOmitSectionDirective(Name);
31 }
32
printName(raw_ostream & OS,StringRef Name)33 static void printName(raw_ostream &OS, StringRef Name) {
34 if (Name.find_first_not_of("0123456789_."
35 "abcdefghijklmnopqrstuvwxyz"
36 "ABCDEFGHIJKLMNOPQRSTUVWXYZ") == Name.npos) {
37 OS << Name;
38 return;
39 }
40 OS << '"';
41 for (const char *B = Name.begin(), *E = Name.end(); B < E; ++B) {
42 if (*B == '"') // Unquoted "
43 OS << "\\\"";
44 else if (*B != '\\') // Neither " or backslash
45 OS << *B;
46 else if (B + 1 == E) // Trailing backslash
47 OS << "\\\\";
48 else {
49 OS << B[0] << B[1]; // Quoted character
50 ++B;
51 }
52 }
53 OS << '"';
54 }
55
PrintSwitchToSection(const MCAsmInfo & MAI,const Triple & T,raw_ostream & OS,const MCExpr * Subsection) const56 void MCSectionELF::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
57 raw_ostream &OS,
58 const MCExpr *Subsection) const {
59 if (ShouldOmitSectionDirective(SectionName, MAI)) {
60 OS << '\t' << getSectionName();
61 if (Subsection) {
62 OS << '\t';
63 Subsection->print(OS, &MAI);
64 }
65 OS << '\n';
66 return;
67 }
68
69 OS << "\t.section\t";
70 printName(OS, getSectionName());
71
72 // Handle the weird solaris syntax if desired.
73 if (MAI.usesSunStyleELFSectionSwitchSyntax() &&
74 !(Flags & ELF::SHF_MERGE)) {
75 if (Flags & ELF::SHF_ALLOC)
76 OS << ",#alloc";
77 if (Flags & ELF::SHF_EXECINSTR)
78 OS << ",#execinstr";
79 if (Flags & ELF::SHF_WRITE)
80 OS << ",#write";
81 if (Flags & ELF::SHF_EXCLUDE)
82 OS << ",#exclude";
83 if (Flags & ELF::SHF_TLS)
84 OS << ",#tls";
85 OS << '\n';
86 return;
87 }
88
89 OS << ",\"";
90 if (Flags & ELF::SHF_ALLOC)
91 OS << 'a';
92 if (Flags & ELF::SHF_EXCLUDE)
93 OS << 'e';
94 if (Flags & ELF::SHF_EXECINSTR)
95 OS << 'x';
96 if (Flags & ELF::SHF_GROUP)
97 OS << 'G';
98 if (Flags & ELF::SHF_WRITE)
99 OS << 'w';
100 if (Flags & ELF::SHF_MERGE)
101 OS << 'M';
102 if (Flags & ELF::SHF_STRINGS)
103 OS << 'S';
104 if (Flags & ELF::SHF_TLS)
105 OS << 'T';
106 if (Flags & ELF::SHF_LINK_ORDER)
107 OS << 'o';
108
109 // If there are target-specific flags, print them.
110 Triple::ArchType Arch = T.getArch();
111 if (Arch == Triple::xcore) {
112 if (Flags & ELF::XCORE_SHF_CP_SECTION)
113 OS << 'c';
114 if (Flags & ELF::XCORE_SHF_DP_SECTION)
115 OS << 'd';
116 } else if (T.isARM() || T.isThumb()) {
117 if (Flags & ELF::SHF_ARM_PURECODE)
118 OS << 'y';
119 }
120
121 OS << '"';
122
123 OS << ',';
124
125 // If comment string is '@', e.g. as on ARM - use '%' instead
126 if (MAI.getCommentString()[0] == '@')
127 OS << '%';
128 else
129 OS << '@';
130
131 if (Type == ELF::SHT_INIT_ARRAY)
132 OS << "init_array";
133 else if (Type == ELF::SHT_FINI_ARRAY)
134 OS << "fini_array";
135 else if (Type == ELF::SHT_PREINIT_ARRAY)
136 OS << "preinit_array";
137 else if (Type == ELF::SHT_NOBITS)
138 OS << "nobits";
139 else if (Type == ELF::SHT_NOTE)
140 OS << "note";
141 else if (Type == ELF::SHT_PROGBITS)
142 OS << "progbits";
143 else if (Type == ELF::SHT_X86_64_UNWIND)
144 OS << "unwind";
145 else if (Type == ELF::SHT_MIPS_DWARF)
146 // Print hex value of the flag while we do not have
147 // any standard symbolic representation of the flag.
148 OS << "0x7000001e";
149 else if (Type == ELF::SHT_LLVM_ODRTAB)
150 OS << "llvm_odrtab";
151 else if (Type == ELF::SHT_LLVM_LINKER_OPTIONS)
152 OS << "llvm_linker_options";
153 else if (Type == ELF::SHT_LLVM_CALL_GRAPH_PROFILE)
154 OS << "llvm_call_graph_profile";
155 else
156 report_fatal_error("unsupported type 0x" + Twine::utohexstr(Type) +
157 " for section " + getSectionName());
158
159 if (EntrySize) {
160 assert(Flags & ELF::SHF_MERGE);
161 OS << "," << EntrySize;
162 }
163
164 if (Flags & ELF::SHF_GROUP) {
165 OS << ",";
166 printName(OS, Group->getName());
167 OS << ",comdat";
168 }
169
170 if (Flags & ELF::SHF_LINK_ORDER) {
171 assert(AssociatedSymbol);
172 OS << ",";
173 printName(OS, AssociatedSymbol->getName());
174 }
175
176 if (isUnique())
177 OS << ",unique," << UniqueID;
178
179 OS << '\n';
180
181 if (Subsection) {
182 OS << "\t.subsection\t";
183 Subsection->print(OS, &MAI);
184 OS << '\n';
185 }
186 }
187
UseCodeAlign() const188 bool MCSectionELF::UseCodeAlign() const {
189 return getFlags() & ELF::SHF_EXECINSTR;
190 }
191
isVirtualSection() const192 bool MCSectionELF::isVirtualSection() const {
193 return getType() == ELF::SHT_NOBITS;
194 }
195