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/MCContext.h"
  12 #include "llvm/Support/raw_ostream.h"
  13 #include "llvm/MC/MCAsmInfo.h"
  14
  15 using namespace llvm;
  16
  17 MCSectionELF *MCSectionELF::
  18 Create(const StringRef &Section, unsigned Type, unsigned Flags,
  19        SectionKind K, bool isExplicit, MCContext &Ctx) {
  20   return new (Ctx) MCSectionELF(Section, Type, Flags, K, isExplicit);
  21 }
  22
  23 // ShouldOmitSectionDirective - Decides whether a '.section' directive
  24 // should be printed before the section name
  25 bool MCSectionELF::ShouldOmitSectionDirective(const char *Name,
  26                                         const MCAsmInfo &MAI) const {
  27
  28   // FIXME: Does .section .bss/.data/.text work everywhere??
  29   if (strcmp(Name, ".text") == 0 ||
  30       strcmp(Name, ".data") == 0 ||
  31       (strcmp(Name, ".bss") == 0 &&
  32        !MAI.usesELFSectionDirectiveForBSS()))
  33     return true;
  34
  35   return false;
  36 }
  37
  38 // ShouldPrintSectionType - Only prints the section type if supported
  39 bool MCSectionELF::ShouldPrintSectionType(unsigned Ty) const {
  40
  41   if (IsExplicit && !(Ty == SHT_NOBITS || Ty == SHT_PROGBITS))
  42     return false;
  43
  44   return true;
  45 }
  46
  47 void MCSectionELF::PrintSwitchToSection(const MCAsmInfo &MAI,
  48                                         raw_ostream &OS) const {
  49
  50   if (ShouldOmitSectionDirective(SectionName.c_str(), MAI)) {
  51     OS << '\t' << getSectionName() << '\n';
  52     return;
  53   }
  54
  55   OS << "\t.section\t" << getSectionName();
  56
  57   // Handle the weird solaris syntax if desired.
  58   if (MAI.usesSunStyleELFSectionSwitchSyntax() &&
  59       !(Flags & MCSectionELF::SHF_MERGE)) {
  60     if (Flags & MCSectionELF::SHF_ALLOC)
  61       OS << ",#alloc";
  62     if (Flags & MCSectionELF::SHF_EXECINSTR)
  63       OS << ",#execinstr";
  64     if (Flags & MCSectionELF::SHF_WRITE)
  65       OS << ",#write";
  66     if (Flags & MCSectionELF::SHF_TLS)
  67       OS << ",#tls";
  68   } else {
  69     OS << ",\"";
  70     if (Flags & MCSectionELF::SHF_ALLOC)
  71       OS << 'a';
  72     if (Flags & MCSectionELF::SHF_EXECINSTR)
  73       OS << 'x';
  74     if (Flags & MCSectionELF::SHF_WRITE)
  75       OS << 'w';
  76     if (Flags & MCSectionELF::SHF_MERGE)
  77       OS << 'M';
  78     if (Flags & MCSectionELF::SHF_STRINGS)
  79       OS << 'S';
  80     if (Flags & MCSectionELF::SHF_TLS)
  81       OS << 'T';
  82
  83     // If there are target-specific flags, print them.
  84     if (Flags & ~MCSectionELF::TARGET_INDEP_SHF)
  85       PrintTargetSpecificSectionFlags(MAI, OS);
  86
  87     OS << '"';
  88
  89     if (ShouldPrintSectionType(Type)) {
  90       OS << ',';
  91
  92       // If comment string is '@', e.g. as on ARM - use '%' instead
  93       if (MAI.getCommentString()[0] == '@')
  94         OS << '%';
  95       else
  96         OS << '@';
  97
  98       if (Type == MCSectionELF::SHT_INIT_ARRAY)
  99         OS << "init_array";
 100       else if (Type == MCSectionELF::SHT_FINI_ARRAY)
 101         OS << "fini_array";
 102       else if (Type == MCSectionELF::SHT_PREINIT_ARRAY)
 103         OS << "preinit_array";
 104       else if (Type == MCSectionELF::SHT_NOBITS)
 105         OS << "nobits";
 106       else if (Type == MCSectionELF::SHT_PROGBITS)
 107         OS << "progbits";
 108
 109       if (getKind().isMergeable1ByteCString()) {
 110         OS << ",1";
 111       } else if (getKind().isMergeable2ByteCString()) {
 112         OS << ",2";
 113       } else if (getKind().isMergeable4ByteCString() ||
 114                  getKind().isMergeableConst4()) {
 115         OS << ",4";
 116       } else if (getKind().isMergeableConst8()) {
 117         OS << ",8";
 118       } else if (getKind().isMergeableConst16()) {
 119         OS << ",16";
 120       }
 121     }
 122   }
 123
 124   OS << '\n';
 125 }
 126
 127 // HasCommonSymbols - True if this section holds common symbols, this is
 128 // indicated on the ELF object file by a symbol with SHN_COMMON section
 129 // header index.
 130 bool MCSectionELF::HasCommonSymbols() const {
 131
 132   if (strncmp(SectionName.c_str(), ".gnu.linkonce.", 14) == 0)
 133     return true;
 134
 135   return false;
 136 }
 137
 138