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 20 MCSectionELF::~MCSectionELF() {} // anchor. 21 22 // ShouldOmitSectionDirective - Decides whether a '.section' directive 23 // should be printed before the section name 24 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 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 58 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 } 152 153 bool MCSectionELF::UseCodeAlign() const { 154 return getFlags() & ELF::SHF_EXECINSTR; 155 } 156 157 bool MCSectionELF::isVirtualSection() const { 158 return getType() == ELF::SHT_NOBITS; 159 } 160 161 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