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/MC/MCAsmInfo.h"
12 #include "llvm/MC/MCContext.h"
13 #include "llvm/MC/MCExpr.h"
14 #include "llvm/MC/MCSymbol.h"
15 #include "llvm/Support/ELF.h"
16 #include "llvm/Support/raw_ostream.h"
17
18 using namespace llvm;
19
~MCSectionELF()20 MCSectionELF::~MCSectionELF() {} // anchor.
21
22 // ShouldOmitSectionDirective - Decides whether a '.section' directive
23 // should be printed before the section name
ShouldOmitSectionDirective(StringRef Name,const MCAsmInfo & MAI) const24 bool MCSectionELF::ShouldOmitSectionDirective(StringRef Name,
25 const MCAsmInfo &MAI) const {
26
27 // FIXME: Does .section .bss/.data/.text work everywhere??
28 if (Name == ".text" || Name == ".data" ||
29 (Name == ".bss" && !MAI.usesELFSectionDirectiveForBSS()))
30 return true;
31
32 return false;
33 }
34
printName(raw_ostream & OS,StringRef Name)35 static void printName(raw_ostream &OS, StringRef Name) {
36 if (Name.find_first_not_of("0123456789_."
37 "abcdefghijklmnopqrstuvwxyz"
38 "ABCDEFGHIJKLMNOPQRSTUVWXYZ") == Name.npos) {
39 OS << Name;
40 return;
41 }
42 OS << '"';
43 for (const char *B = Name.begin(), *E = Name.end(); B < E; ++B) {
44 if (*B == '"') // Unquoted "
45 OS << "\\\"";
46 else if (*B != '\\') // Neither " or backslash
47 OS << *B;
48 else if (B + 1 == E) // Trailing backslash
49 OS << "\\\\";
50 else {
51 OS << B[0] << B[1]; // Quoted character
52 ++B;
53 }
54 }
55 OS << '"';
56 }
57
PrintSwitchToSection(const MCAsmInfo & MAI,raw_ostream & OS,const MCExpr * Subsection) const58 void MCSectionELF::PrintSwitchToSection(const MCAsmInfo &MAI,
59 raw_ostream &OS,
60 const MCExpr *Subsection) const {
61
62 if (ShouldOmitSectionDirective(SectionName, MAI)) {
63 OS << '\t' << getSectionName();
64 if (Subsection)
65 OS << '\t' << *Subsection;
66 OS << '\n';
67 return;
68 }
69
70 OS << "\t.section\t";
71 printName(OS, getSectionName());
72
73 // Handle the weird solaris syntax if desired.
74 if (MAI.usesSunStyleELFSectionSwitchSyntax() &&
75 !(Flags & ELF::SHF_MERGE)) {
76 if (Flags & ELF::SHF_ALLOC)
77 OS << ",#alloc";
78 if (Flags & ELF::SHF_EXECINSTR)
79 OS << ",#execinstr";
80 if (Flags & ELF::SHF_WRITE)
81 OS << ",#write";
82 if (Flags & ELF::SHF_EXCLUDE)
83 OS << ",#exclude";
84 if (Flags & ELF::SHF_TLS)
85 OS << ",#tls";
86 OS << '\n';
87 return;
88 }
89
90 OS << ",\"";
91 if (Flags & ELF::SHF_ALLOC)
92 OS << 'a';
93 if (Flags & ELF::SHF_EXCLUDE)
94 OS << 'e';
95 if (Flags & ELF::SHF_EXECINSTR)
96 OS << 'x';
97 if (Flags & ELF::SHF_GROUP)
98 OS << 'G';
99 if (Flags & ELF::SHF_WRITE)
100 OS << 'w';
101 if (Flags & ELF::SHF_MERGE)
102 OS << 'M';
103 if (Flags & ELF::SHF_STRINGS)
104 OS << 'S';
105 if (Flags & ELF::SHF_TLS)
106 OS << 'T';
107
108 // If there are target-specific flags, print them.
109 if (Flags & ELF::XCORE_SHF_CP_SECTION)
110 OS << 'c';
111 if (Flags & ELF::XCORE_SHF_DP_SECTION)
112 OS << 'd';
113
114 OS << '"';
115
116 OS << ',';
117
118 // If comment string is '@', e.g. as on ARM - use '%' instead
119 if (MAI.getCommentString()[0] == '@')
120 OS << '%';
121 else
122 OS << '@';
123
124 if (Type == ELF::SHT_INIT_ARRAY)
125 OS << "init_array";
126 else if (Type == ELF::SHT_FINI_ARRAY)
127 OS << "fini_array";
128 else if (Type == ELF::SHT_PREINIT_ARRAY)
129 OS << "preinit_array";
130 else if (Type == ELF::SHT_NOBITS)
131 OS << "nobits";
132 else if (Type == ELF::SHT_NOTE)
133 OS << "note";
134 else if (Type == ELF::SHT_PROGBITS)
135 OS << "progbits";
136
137 if (EntrySize) {
138 assert(Flags & ELF::SHF_MERGE);
139 OS << "," << EntrySize;
140 }
141
142 if (Flags & ELF::SHF_GROUP) {
143 OS << ",";
144 printName(OS, Group->getName());
145 OS << ",comdat";
146 }
147 OS << '\n';
148
149 if (Subsection)
150 OS << "\t.subsection\t" << *Subsection << '\n';
151 }
152
UseCodeAlign() const153 bool MCSectionELF::UseCodeAlign() const {
154 return getFlags() & ELF::SHF_EXECINSTR;
155 }
156
isVirtualSection() const157 bool MCSectionELF::isVirtualSection() const {
158 return getType() == ELF::SHT_NOBITS;
159 }
160
DetermineEntrySize(SectionKind Kind)161 unsigned MCSectionELF::DetermineEntrySize(SectionKind Kind) {
162 if (Kind.isMergeable1ByteCString()) return 1;
163 if (Kind.isMergeable2ByteCString()) return 2;
164 if (Kind.isMergeable4ByteCString()) return 4;
165 if (Kind.isMergeableConst4()) return 4;
166 if (Kind.isMergeableConst8()) return 8;
167 if (Kind.isMergeableConst16()) return 16;
168 return 0;
169 }
170