lib/MC/MCSectionELF.cpp

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