TargetLoweringObjectFileImpl.cpp

//===-- llvm/CodeGen/TargetLoweringObjectFileImpl.cpp - Object File Info --===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements classes used to handle lowerings specific to common
// object file formats.
//
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/GlobalVariable.h"
#include "llvm/CodeGen/MachineModuleInfoImpls.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCExpr.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSectionCOFF.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Target/Mangler.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/ELF.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Triple.h"
using namespace llvm;
using namespace dwarf;

//===----------------------------------------------------------------------===//
//                                  ELF
//===----------------------------------------------------------------------===//

void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
                                             const TargetMachine &TM) {
  TargetLoweringObjectFile::Initialize(Ctx, TM);

  BSSSection =
    getContext().getELFSection(".bss", ELF::SHT_NOBITS,
                               ELF::SHF_WRITE |ELF::SHF_ALLOC,
                               SectionKind::getBSS());

  TextSection =
    getContext().getELFSection(".text", ELF::SHT_PROGBITS,
                               ELF::SHF_EXECINSTR |
                               ELF::SHF_ALLOC,
                               SectionKind::getText());

  DataSection =
    getContext().getELFSection(".data", ELF::SHT_PROGBITS,
                               ELF::SHF_WRITE |ELF::SHF_ALLOC,
                               SectionKind::getDataRel());

  ReadOnlySection =
    getContext().getELFSection(".rodata", ELF::SHT_PROGBITS,
                               ELF::SHF_ALLOC,
                               SectionKind::getReadOnly());

  TLSDataSection =
    getContext().getELFSection(".tdata", ELF::SHT_PROGBITS,
                               ELF::SHF_ALLOC | ELF::SHF_TLS |
                               ELF::SHF_WRITE,
                               SectionKind::getThreadData());

  TLSBSSSection =
    getContext().getELFSection(".tbss", ELF::SHT_NOBITS,
                               ELF::SHF_ALLOC | ELF::SHF_TLS |
                               ELF::SHF_WRITE,
                               SectionKind::getThreadBSS());

  DataRelSection =
    getContext().getELFSection(".data.rel", ELF::SHT_PROGBITS,
                               ELF::SHF_ALLOC |ELF::SHF_WRITE,
                               SectionKind::getDataRel());

  DataRelLocalSection =
    getContext().getELFSection(".data.rel.local", ELF::SHT_PROGBITS,
                               ELF::SHF_ALLOC |ELF::SHF_WRITE,
                               SectionKind::getDataRelLocal());

  DataRelROSection =
    getContext().getELFSection(".data.rel.ro", ELF::SHT_PROGBITS,
                               ELF::SHF_ALLOC |ELF::SHF_WRITE,
                               SectionKind::getReadOnlyWithRel());

  DataRelROLocalSection =
    getContext().getELFSection(".data.rel.ro.local", ELF::SHT_PROGBITS,
                               ELF::SHF_ALLOC |ELF::SHF_WRITE,
                               SectionKind::getReadOnlyWithRelLocal());

  MergeableConst4Section =
    getContext().getELFSection(".rodata.cst4", ELF::SHT_PROGBITS,
                               ELF::SHF_ALLOC |ELF::SHF_MERGE,
                               SectionKind::getMergeableConst4());

  MergeableConst8Section =
    getContext().getELFSection(".rodata.cst8", ELF::SHT_PROGBITS,
                               ELF::SHF_ALLOC |ELF::SHF_MERGE,
                               SectionKind::getMergeableConst8());

  MergeableConst16Section =
    getContext().getELFSection(".rodata.cst16", ELF::SHT_PROGBITS,
                               ELF::SHF_ALLOC |ELF::SHF_MERGE,
                               SectionKind::getMergeableConst16());

  StaticCtorSection =
    getContext().getELFSection(".ctors", ELF::SHT_PROGBITS,
                               ELF::SHF_ALLOC |ELF::SHF_WRITE,
                               SectionKind::getDataRel());

  StaticDtorSection =
    getContext().getELFSection(".dtors", ELF::SHT_PROGBITS,
                               ELF::SHF_ALLOC |ELF::SHF_WRITE,
                               SectionKind::getDataRel());

  // Exception Handling Sections.

  // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
  // it contains relocatable pointers.  In PIC mode, this is probably a big
  // runtime hit for C++ apps.  Either the contents of the LSDA need to be
  // adjusted or this should be a data section.
  LSDASection =
    getContext().getELFSection(".gcc_except_table", ELF::SHT_PROGBITS,
                               ELF::SHF_ALLOC,
                               SectionKind::getReadOnly());
  // Debug Info Sections.
  DwarfAbbrevSection =
    getContext().getELFSection(".debug_abbrev", ELF::SHT_PROGBITS, 0,
                               SectionKind::getMetadata());
  DwarfInfoSection =
    getContext().getELFSection(".debug_info", ELF::SHT_PROGBITS, 0,
                               SectionKind::getMetadata());
  DwarfLineSection =
    getContext().getELFSection(".debug_line", ELF::SHT_PROGBITS, 0,
                               SectionKind::getMetadata());
  DwarfFrameSection =
    getContext().getELFSection(".debug_frame", ELF::SHT_PROGBITS, 0,
                               SectionKind::getMetadata());
  DwarfPubNamesSection =
    getContext().getELFSection(".debug_pubnames", ELF::SHT_PROGBITS, 0,
                               SectionKind::getMetadata());
  DwarfPubTypesSection =
    getContext().getELFSection(".debug_pubtypes", ELF::SHT_PROGBITS, 0,
                               SectionKind::getMetadata());
  DwarfStrSection =
    getContext().getELFSection(".debug_str", ELF::SHT_PROGBITS, 0,
                               SectionKind::getMetadata());
  DwarfLocSection =
    getContext().getELFSection(".debug_loc", ELF::SHT_PROGBITS, 0,
                               SectionKind::getMetadata());
  DwarfARangesSection =
    getContext().getELFSection(".debug_aranges", ELF::SHT_PROGBITS, 0,
                               SectionKind::getMetadata());
  DwarfRangesSection =
    getContext().getELFSection(".debug_ranges", ELF::SHT_PROGBITS, 0,
                               SectionKind::getMetadata());
  DwarfMacroInfoSection =
    getContext().getELFSection(".debug_macinfo", ELF::SHT_PROGBITS, 0,
                               SectionKind::getMetadata());
}

const MCSection *TargetLoweringObjectFileELF::getEHFrameSection() const {
  return getContext().getELFSection(".eh_frame", ELF::SHT_PROGBITS,
                                    ELF::SHF_ALLOC,
                                    SectionKind::getDataRel());
}

static SectionKind
getELFKindForNamedSection(StringRef Name, SectionKind K) {
  // FIXME: Why is this here? Codegen is should not be in the business
  // of figuring section flags. If the user wrote section(".eh_frame"),
  // we should just pass that to MC which will defer to the assembly
  // or use its default if producing an object file.
  if (Name.empty() || Name[0] != '.') return K;

  // Some lame default implementation based on some magic section names.
  if (Name == ".bss" ||
      Name.startswith(".bss.") ||
      Name.startswith(".gnu.linkonce.b.") ||
      Name.startswith(".llvm.linkonce.b.") ||
      Name == ".sbss" ||
      Name.startswith(".sbss.") ||
      Name.startswith(".gnu.linkonce.sb.") ||
      Name.startswith(".llvm.linkonce.sb."))
    return SectionKind::getBSS();

  if (Name == ".tdata" ||
      Name.startswith(".tdata.") ||
      Name.startswith(".gnu.linkonce.td.") ||