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/MCSymbol.h"
14 #include "llvm/Support/raw_ostream.h"
15 using namespace llvm;
16 
17 MCSectionELF::~MCSectionELF() {} // anchor.
18 
19 // ShouldOmitSectionDirective - Decides whether a '.section' directive
20 // should be printed before the section name
21 bool MCSectionELF::ShouldOmitSectionDirective(StringRef Name,
22                                               const MCAsmInfo &MAI) const {
23 
24   // FIXME: Does .section .bss/.data/.text work everywhere??
25   if (Name == ".text" || Name == ".data" ||
26       (Name == ".bss" && !MAI.usesELFSectionDirectiveForBSS()))
27     return true;
28 
29   return false;
30 }
31 
32 // ShouldPrintSectionType - Only prints the section type if supported
33 bool MCSectionELF::ShouldPrintSectionType(unsigned Ty) const {
34   if (IsExplicit && !(Ty == SHT_NOBITS || Ty == SHT_PROGBITS))
35     return false;
36 
37   return true;
38 }
39 
40 void MCSectionELF::PrintSwitchToSection(const MCAsmInfo &MAI,
41                                         raw_ostream &OS) const {
42 
43   if (ShouldOmitSectionDirective(SectionName, MAI)) {
44     OS << '\t' << getSectionName() << '\n';
45     return;
46   }
47 
48   OS << "\t.section\t" << getSectionName();
49 
50   // Handle the weird solaris syntax if desired.
51   if (MAI.usesSunStyleELFSectionSwitchSyntax() &&
52       !(Flags & MCSectionELF::SHF_MERGE)) {
53     if (Flags & MCSectionELF::SHF_ALLOC)
54       OS << ",#alloc";
55     if (Flags & MCSectionELF::SHF_EXECINSTR)
56       OS << ",#execinstr";
57     if (Flags & MCSectionELF::SHF_WRITE)
58       OS << ",#write";
59     if (Flags & MCSectionELF::SHF_TLS)
60       OS << ",#tls";
61     OS << '\n';
62     return;
63   }
64 
65   OS << ",\"";
66   if (Flags & MCSectionELF::SHF_ALLOC)
67     OS << 'a';
68   if (Flags & MCSectionELF::SHF_EXECINSTR)
69     OS << 'x';
70   if (Flags & MCSectionELF::SHF_WRITE)
71     OS << 'w';
72   if (Flags & MCSectionELF::SHF_MERGE)
73     OS << 'M';
74   if (Flags & MCSectionELF::SHF_STRINGS)
75     OS << 'S';
76   if (Flags & MCSectionELF::SHF_TLS)
77     OS << 'T';
78 
79   // If there are target-specific flags, print them.
80   if (Flags & MCSectionELF::XCORE_SHF_CP_SECTION)
81     OS << 'c';
82   if (Flags & MCSectionELF::XCORE_SHF_DP_SECTION)
83     OS << 'd';
84 
85   OS << '"';
86 
87   if (ShouldPrintSectionType(Type)) {
88     OS << ',';
89 
90     // If comment string is '@', e.g. as on ARM - use '%' instead
91     if (MAI.getCommentString()[0] == '@')
92       OS << '%';
93     else
94       OS << '@';
95 
96     if (Type == MCSectionELF::SHT_INIT_ARRAY)
97       OS << "init_array";
98     else if (Type == MCSectionELF::SHT_FINI_ARRAY)
99       OS << "fini_array";
100     else if (Type == MCSectionELF::SHT_PREINIT_ARRAY)
101       OS << "preinit_array";
102     else if (Type == MCSectionELF::SHT_NOBITS)
103       OS << "nobits";
104     else if (Type == MCSectionELF::SHT_PROGBITS)
105       OS << "progbits";
106 
107     if (getKind().isMergeable1ByteCString()) {
108       OS << ",1";
109     } else if (getKind().isMergeable2ByteCString()) {
110       OS << ",2";
111     } else if (getKind().isMergeable4ByteCString() ||
112                getKind().isMergeableConst4()) {
113       OS << ",4";
114     } else if (getKind().isMergeableConst8()) {
115       OS << ",8";
116     } else if (getKind().isMergeableConst16()) {
117       OS << ",16";
118     }
119   }
120 
121   OS << '\n';
122 }
123 
124 // HasCommonSymbols - True if this section holds common symbols, this is
125 // indicated on the ELF object file by a symbol with SHN_COMMON section
126 // header index.
127 bool MCSectionELF::HasCommonSymbols() const {
128 
129   if (StringRef(SectionName).startswith(".gnu.linkonce."))
130     return true;
131 
132   return false;
133 }
134 
135 
136