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
18using namespace llvm;
19
20MCSectionELF::~MCSectionELF() {} // anchor.
21
22// ShouldOmitSectionDirective - Decides whether a '.section' directive
23// should be printed before the section name
24bool 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
35static 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
58void 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
153bool MCSectionELF::UseCodeAlign() const {
154  return getFlags() & ELF::SHF_EXECINSTR;
155}
156
157bool MCSectionELF::isVirtualSection() const {
158  return getType() == ELF::SHT_NOBITS;
159}
160
161unsigned 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