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llvm-mirror/lib/CodeGen/TargetLoweringObjectFileImpl.cpp
Rafael Espindola 8e44a53856 Explain FIXME. 
llvm-svn: 131952
2011-05-24 03:10:31 +00:00

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//===-- 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/MCStreamer.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());
}
MCSymbol *
TargetLoweringObjectFileELF::getCFIPersonalitySymbol(const GlobalValue *GV,
Mangler *Mang,
MachineModuleInfo *MMI) const {
unsigned Encoding = getPersonalityEncoding();
switch (Encoding & 0x70) {
default:
report_fatal_error("We do not support this DWARF encoding yet!");
case dwarf::DW_EH_PE_absptr:
return Mang->getSymbol(GV);
break;
case dwarf::DW_EH_PE_pcrel: {
Twine FullName = StringRef("DW.ref.") + Mang->getSymbol(GV)->getName();
return getContext().GetOrCreateSymbol(FullName);
break;
}
}
}
void TargetLoweringObjectFileELF::emitPersonalityValue(MCStreamer &Streamer,
const TargetMachine &TM,
const MCSymbol *Sym) const {
Twine FullName = StringRef("DW.ref.") + Sym->getName();
MCSymbol *Label = getContext().GetOrCreateSymbol(FullName);
Streamer.EmitSymbolAttribute(Label, MCSA_Hidden);
Streamer.EmitSymbolAttribute(Label, MCSA_Weak);
Twine SectionName = StringRef(".data.") + Label->getName();
SmallString<64> NameData;
SectionName.toVector(NameData);
unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP;
const MCSection *Sec = getContext().getELFSection(NameData,
ELF::SHT_PROGBITS,
Flags,
SectionKind::getDataRel(),
0, Label->getName());
Streamer.SwitchSection(Sec);
Streamer.EmitValueToAlignment(8);
Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject);
const MCExpr *E = MCConstantExpr::Create(8, getContext());
Streamer.EmitELFSize(Label, E);
Streamer.EmitLabel(Label);
unsigned Size = TM.getTargetData()->getPointerSize();
Streamer.EmitSymbolValue(Sym, Size);
}
static SectionKind
getELFKindForNamedSection(StringRef Name, SectionKind K) {
// N.B.: The defaults used in here are no the same ones used in MC.
// We follow gcc, MC follows gas. For example, given ".section .eh_frame",
// both gas and MC will produce a section with no flags. Given
// section(".eh_frame") gcc will produce
// .section .eh_frame,"a",@progbits
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.") ||
Name.startswith(".llvm.linkonce.td."))
return SectionKind::getThreadData();
if (Name == ".tbss" ||
Name.startswith(".tbss.") ||
Name.startswith(".gnu.linkonce.tb.") ||
Name.startswith(".llvm.linkonce.tb."))
return SectionKind::getThreadBSS();
if (Name == ".eh_frame")
return SectionKind::getReadOnlyWithRel();
return K;
}
static unsigned getELFSectionType(StringRef Name, SectionKind K) {
if (Name == ".init_array")
return ELF::SHT_INIT_ARRAY;
if (Name == ".fini_array")
return ELF::SHT_FINI_ARRAY;
if (Name == ".preinit_array")
return ELF::SHT_PREINIT_ARRAY;
if (K.isBSS() || K.isThreadBSS())
return ELF::SHT_NOBITS;
return ELF::SHT_PROGBITS;
}
static unsigned
getELFSectionFlags(SectionKind K) {
unsigned Flags = 0;
if (!K.isMetadata())
Flags |= ELF::SHF_ALLOC;
if (K.isText())
Flags |= ELF::SHF_EXECINSTR;
if (K.isWriteable() && !K.isReadOnlyWithRel())
Flags |= ELF::SHF_WRITE;
if (K.isThreadLocal())
Flags |= ELF::SHF_TLS;
// K.isMergeableConst() is left out to honour PR4650
if (K.isMergeableCString() || K.isMergeableConst4() ||
K.isMergeableConst8() || K.isMergeableConst16())
Flags |= ELF::SHF_MERGE;
if (K.isMergeableCString())
Flags |= ELF::SHF_STRINGS;
return Flags;
}
const MCSection *TargetLoweringObjectFileELF::
getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
Mangler *Mang, const TargetMachine &TM) const {
StringRef SectionName = GV->getSection();
// Infer section flags from the section name if we can.
Kind = getELFKindForNamedSection(SectionName, Kind);
return getContext().getELFSection(SectionName,
getELFSectionType(SectionName, Kind),
getELFSectionFlags(Kind), Kind);
}
/// getSectionPrefixForGlobal - Return the section prefix name used by options
/// FunctionsSections and DataSections.
static const char *getSectionPrefixForGlobal(SectionKind Kind) {
if (Kind.isText()) return ".text.";
if (Kind.isReadOnly()) return ".rodata.";
if (Kind.isThreadData()) return ".tdata.";
if (Kind.isThreadBSS()) return ".tbss.";
if (Kind.isDataNoRel()) return ".data.";
if (Kind.isDataRelLocal()) return ".data.rel.local.";
if (Kind.isDataRel()) return ".data.rel.";
if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local.";
assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
return ".data.rel.ro.";
}
const MCSection *TargetLoweringObjectFileELF::
SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
Mangler *Mang, const TargetMachine &TM) const {
// If we have -ffunction-section or -fdata-section then we should emit the
// global value to a uniqued section specifically for it.
bool EmitUniquedSection;
if (Kind.isText())
EmitUniquedSection = TM.getFunctionSections();
else
EmitUniquedSection = TM.getDataSections();
// If this global is linkonce/weak and the target handles this by emitting it
// into a 'uniqued' section name, create and return the section now.
if ((GV->isWeakForLinker() || EmitUniquedSection) &&
!Kind.isCommon() && !Kind.isBSS()) {
const char *Prefix;
Prefix = getSectionPrefixForGlobal(Kind);
SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
MCSymbol *Sym = Mang->getSymbol(GV);
Name.append(Sym->getName().begin(), Sym->getName().end());
StringRef Group = "";
unsigned Flags = getELFSectionFlags(Kind);
if (GV->isWeakForLinker()) {
Group = Sym->getName();
Flags |= ELF::SHF_GROUP;
}
return getContext().getELFSection(Name.str(),
getELFSectionType(Name.str(), Kind),
Flags, Kind, 0, Group);
}
if (Kind.isText()) return TextSection;
if (Kind.isMergeable1ByteCString() ||
Kind.isMergeable2ByteCString() ||
Kind.isMergeable4ByteCString()) {
// We also need alignment here.
// FIXME: this is getting the alignment of the character, not the
// alignment of the global!
unsigned Align =
TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
const char *SizeSpec = ".rodata.str1.";
if (Kind.isMergeable2ByteCString())
SizeSpec = ".rodata.str2.";
else if (Kind.isMergeable4ByteCString())
SizeSpec = ".rodata.str4.";
else
assert(Kind.isMergeable1ByteCString() && "unknown string width");
std::string Name = SizeSpec + utostr(Align);
return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
ELF::SHF_ALLOC |
ELF::SHF_MERGE |
ELF::SHF_STRINGS,
Kind);
}
if (Kind.isMergeableConst()) {
if (Kind.isMergeableConst4() && MergeableConst4Section)
return MergeableConst4Section;
if (Kind.isMergeableConst8() && MergeableConst8Section)
return MergeableConst8Section;
if (Kind.isMergeableConst16() && MergeableConst16Section)
return MergeableConst16Section;
return ReadOnlySection; // .const
}
if (Kind.isReadOnly()) return ReadOnlySection;
if (Kind.isThreadData()) return TLSDataSection;
if (Kind.isThreadBSS()) return TLSBSSSection;
// Note: we claim that common symbols are put in BSSSection, but they are
// really emitted with the magic .comm directive, which creates a symbol table
// entry but not a section.
if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
if (Kind.isDataNoRel()) return DataSection;
if (Kind.isDataRelLocal()) return DataRelLocalSection;
if (Kind.isDataRel()) return DataRelSection;
if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
return DataRelROSection;
}
/// getSectionForConstant - Given a mergeable constant with the
/// specified size and relocation information, return a section that it
/// should be placed in.
const MCSection *TargetLoweringObjectFileELF::
getSectionForConstant(SectionKind Kind) const {
if (Kind.isMergeableConst4() && MergeableConst4Section)
return MergeableConst4Section;
if (Kind.isMergeableConst8() && MergeableConst8Section)
return MergeableConst8Section;
if (Kind.isMergeableConst16() && MergeableConst16Section)
return MergeableConst16Section;
if (Kind.isReadOnly())
return ReadOnlySection;
if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
return DataRelROSection;
}
const MCExpr *TargetLoweringObjectFileELF::
getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
MachineModuleInfo *MMI,
unsigned Encoding, MCStreamer &Streamer) const {
if (Encoding & dwarf::DW_EH_PE_indirect) {
MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
SmallString<128> Name;
Mang->getNameWithPrefix(Name, GV, true);
Name += ".DW.stub";
// Add information about the stub reference to ELFMMI so that the stub
// gets emitted by the asmprinter.
MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
if (StubSym.getPointer() == 0) {
MCSymbol *Sym = Mang->getSymbol(GV);
StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
}
return TargetLoweringObjectFile::
getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
}
return TargetLoweringObjectFile::
getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
}
//===----------------------------------------------------------------------===//
// MachO
//===----------------------------------------------------------------------===//
void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
const TargetMachine &TM) {
IsFunctionEHFrameSymbolPrivate = false;
SupportsWeakOmittedEHFrame = false;
// .comm doesn't support alignment before Leopard.
Triple T(((LLVMTargetMachine&)TM).getTargetTriple());
if (T.isMacOSX() && T.isMacOSXVersionLT(10, 5))
CommDirectiveSupportsAlignment = false;
TargetLoweringObjectFile::Initialize(Ctx, TM);
TextSection // .text
= getContext().getMachOSection("__TEXT", "__text",
MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
SectionKind::getText());
DataSection // .data
= getContext().getMachOSection("__DATA", "__data", 0,
SectionKind::getDataRel());
TLSDataSection // .tdata
= getContext().getMachOSection("__DATA", "__thread_data",
MCSectionMachO::S_THREAD_LOCAL_REGULAR,
SectionKind::getDataRel());
TLSBSSSection // .tbss
= getContext().getMachOSection("__DATA", "__thread_bss",
MCSectionMachO::S_THREAD_LOCAL_ZEROFILL,
SectionKind::getThreadBSS());
// TODO: Verify datarel below.
TLSTLVSection // .tlv
= getContext().getMachOSection("__DATA", "__thread_vars",
MCSectionMachO::S_THREAD_LOCAL_VARIABLES,
SectionKind::getDataRel());
TLSThreadInitSection
= getContext().getMachOSection("__DATA", "__thread_init",
MCSectionMachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
SectionKind::getDataRel());
CStringSection // .cstring
= getContext().getMachOSection("__TEXT", "__cstring",
MCSectionMachO::S_CSTRING_LITERALS,
SectionKind::getMergeable1ByteCString());
UStringSection
= getContext().getMachOSection("__TEXT","__ustring", 0,
SectionKind::getMergeable2ByteCString());
FourByteConstantSection // .literal4
= getContext().getMachOSection("__TEXT", "__literal4",
MCSectionMachO::S_4BYTE_LITERALS,
SectionKind::getMergeableConst4());
EightByteConstantSection // .literal8
= getContext().getMachOSection("__TEXT", "__literal8",
MCSectionMachO::S_8BYTE_LITERALS,
SectionKind::getMergeableConst8());
// ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
// to using it in -static mode.
SixteenByteConstantSection = 0;
if (TM.getRelocationModel() != Reloc::Static &&
TM.getTargetData()->getPointerSize() == 32)
SixteenByteConstantSection = // .literal16
getContext().getMachOSection("__TEXT", "__literal16",
MCSectionMachO::S_16BYTE_LITERALS,
SectionKind::getMergeableConst16());
ReadOnlySection // .const
= getContext().getMachOSection("__TEXT", "__const", 0,
SectionKind::getReadOnly());
TextCoalSection
= getContext().getMachOSection("__TEXT", "__textcoal_nt",
MCSectionMachO::S_COALESCED |
MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
SectionKind::getText());
ConstTextCoalSection
= getContext().getMachOSection("__TEXT", "__const_coal",
MCSectionMachO::S_COALESCED,
SectionKind::getReadOnly());
ConstDataSection // .const_data
= getContext().getMachOSection("__DATA", "__const", 0,
SectionKind::getReadOnlyWithRel());
DataCoalSection
= getContext().getMachOSection("__DATA","__datacoal_nt",
MCSectionMachO::S_COALESCED,
SectionKind::getDataRel());
DataCommonSection
= getContext().getMachOSection("__DATA","__common",
MCSectionMachO::S_ZEROFILL,
SectionKind::getBSS());
DataBSSSection
= getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
SectionKind::getBSS());
LazySymbolPointerSection
= getContext().getMachOSection("__DATA", "__la_symbol_ptr",
MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
SectionKind::getMetadata());
NonLazySymbolPointerSection
= getContext().getMachOSection("__DATA", "__nl_symbol_ptr",
MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
SectionKind::getMetadata());
if (TM.getRelocationModel() == Reloc::Static) {
StaticCtorSection
= getContext().getMachOSection("__TEXT", "__constructor", 0,
SectionKind::getDataRel());
StaticDtorSection
= getContext().getMachOSection("__TEXT", "__destructor", 0,
SectionKind::getDataRel());
} else {
StaticCtorSection
= getContext().getMachOSection("__DATA", "__mod_init_func",
MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
SectionKind::getDataRel());
StaticDtorSection
= getContext().getMachOSection("__DATA", "__mod_term_func",
MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
SectionKind::getDataRel());
}
// Exception Handling.
LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0,
SectionKind::getReadOnlyWithRel());
// Debug Information.
DwarfAbbrevSection =
getContext().getMachOSection("__DWARF", "__debug_abbrev",
MCSectionMachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfInfoSection =
getContext().getMachOSection("__DWARF", "__debug_info",
MCSectionMachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfLineSection =
getContext().getMachOSection("__DWARF", "__debug_line",
MCSectionMachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfFrameSection =
getContext().getMachOSection("__DWARF", "__debug_frame",
MCSectionMachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfPubNamesSection =
getContext().getMachOSection("__DWARF", "__debug_pubnames",
MCSectionMachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfPubTypesSection =
getContext().getMachOSection("__DWARF", "__debug_pubtypes",
MCSectionMachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfStrSection =
getContext().getMachOSection("__DWARF", "__debug_str",
MCSectionMachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfLocSection =
getContext().getMachOSection("__DWARF", "__debug_loc",
MCSectionMachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfARangesSection =
getContext().getMachOSection("__DWARF", "__debug_aranges",
MCSectionMachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfRangesSection =
getContext().getMachOSection("__DWARF", "__debug_ranges",
MCSectionMachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfMacroInfoSection =
getContext().getMachOSection("__DWARF", "__debug_macinfo",
MCSectionMachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfDebugInlineSection =
getContext().getMachOSection("__DWARF", "__debug_inlined",
MCSectionMachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
TLSExtraDataSection = TLSTLVSection;
}
const MCSection *TargetLoweringObjectFileMachO::getEHFrameSection() const {
return getContext().getMachOSection("__TEXT", "__eh_frame",
MCSectionMachO::S_COALESCED |
MCSectionMachO::S_ATTR_NO_TOC |
MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
MCSectionMachO::S_ATTR_LIVE_SUPPORT,
SectionKind::getReadOnly());
}
const MCSection *TargetLoweringObjectFileMachO::
getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
Mangler *Mang, const TargetMachine &TM) const {
// Parse the section specifier and create it if valid.
StringRef Segment, Section;
unsigned TAA = 0, StubSize = 0;
bool TAAParsed;
std::string ErrorCode =
MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
TAA, TAAParsed, StubSize);
if (!ErrorCode.empty()) {
// If invalid, report the error with report_fatal_error.
report_fatal_error("Global variable '" + GV->getNameStr() +
"' has an invalid section specifier '" + GV->getSection()+
"': " + ErrorCode + ".");
// Fall back to dropping it into the data section.
return DataSection;
}
// Get the section.
const MCSectionMachO *S =
getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
// If TAA wasn't set by ParseSectionSpecifier() above,
// use the value returned by getMachOSection() as a default.
if (!TAAParsed)
TAA = S->getTypeAndAttributes();
// Okay, now that we got the section, verify that the TAA & StubSize agree.
// If the user declared multiple globals with different section flags, we need
// to reject it here.
if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
// If invalid, report the error with report_fatal_error.
report_fatal_error("Global variable '" + GV->getNameStr() +
"' section type or attributes does not match previous"
" section specifier");
}
return S;
}
const MCSection *TargetLoweringObjectFileMachO::
SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
Mangler *Mang, const TargetMachine &TM) const {
// Handle thread local data.
if (Kind.isThreadBSS()) return TLSBSSSection;
if (Kind.isThreadData()) return TLSDataSection;
if (Kind.isText())
return GV->isWeakForLinker() ? TextCoalSection : TextSection;
// If this is weak/linkonce, put this in a coalescable section, either in text
// or data depending on if it is writable.
if (GV->isWeakForLinker()) {
if (Kind.isReadOnly())
return ConstTextCoalSection;
return DataCoalSection;
}
// FIXME: Alignment check should be handled by section classifier.
if (Kind.isMergeable1ByteCString() &&
TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
return CStringSection;
// Do not put 16-bit arrays in the UString section if they have an
// externally visible label, this runs into issues with certain linker
// versions.
if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
return UStringSection;
if (Kind.isMergeableConst()) {
if (Kind.isMergeableConst4())
return FourByteConstantSection;
if (Kind.isMergeableConst8())
return EightByteConstantSection;
if (Kind.isMergeableConst16() && SixteenByteConstantSection)
return SixteenByteConstantSection;
}
// Otherwise, if it is readonly, but not something we can specially optimize,
// just drop it in .const.
if (Kind.isReadOnly())
return ReadOnlySection;
// If this is marked const, put it into a const section. But if the dynamic
// linker needs to write to it, put it in the data segment.
if (Kind.isReadOnlyWithRel())
return ConstDataSection;
// Put zero initialized globals with strong external linkage in the
// DATA, __common section with the .zerofill directive.
if (Kind.isBSSExtern())
return DataCommonSection;
// Put zero initialized globals with local linkage in __DATA,__bss directive
// with the .zerofill directive (aka .lcomm).
if (Kind.isBSSLocal())
return DataBSSSection;
// Otherwise, just drop the variable in the normal data section.
return DataSection;
}
const MCSection *
TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
// If this constant requires a relocation, we have to put it in the data
// segment, not in the text segment.
if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
return ConstDataSection;
if (Kind.isMergeableConst4())
return FourByteConstantSection;
if (Kind.isMergeableConst8())
return EightByteConstantSection;
if (Kind.isMergeableConst16() && SixteenByteConstantSection)
return SixteenByteConstantSection;
return ReadOnlySection; // .const
}
/// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
/// not to emit the UsedDirective for some symbols in llvm.used.
// FIXME: REMOVE this (rdar://7071300)
bool TargetLoweringObjectFileMachO::
shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
/// On Darwin, internally linked data beginning with "L" or "l" does not have
/// the directive emitted (this occurs in ObjC metadata).
if (!GV) return false;
// Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
// FIXME: ObjC metadata is currently emitted as internal symbols that have
// \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and
// this horrible hack can go away.
MCSymbol *Sym = Mang->getSymbol(GV);
if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
return false;
}
return true;
}
const MCExpr *TargetLoweringObjectFileMachO::
getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
MachineModuleInfo *MMI, unsigned Encoding,
MCStreamer &Streamer) const {
// The mach-o version of this method defaults to returning a stub reference.
if (Encoding & DW_EH_PE_indirect) {
MachineModuleInfoMachO &MachOMMI =
MMI->getObjFileInfo<MachineModuleInfoMachO>();
SmallString<128> Name;
Mang->getNameWithPrefix(Name, GV, true);
Name += "$non_lazy_ptr";
// Add information about the stub reference to MachOMMI so that the stub
// gets emitted by the asmprinter.
MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
if (StubSym.getPointer() == 0) {
MCSymbol *Sym = Mang->getSymbol(GV);
StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
}
return TargetLoweringObjectFile::
getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
}
return TargetLoweringObjectFile::
getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
}
MCSymbol *TargetLoweringObjectFileMachO::
getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang,
MachineModuleInfo *MMI) const {
// The mach-o version of this method defaults to returning a stub reference.
MachineModuleInfoMachO &MachOMMI =
MMI->getObjFileInfo<MachineModuleInfoMachO>();
SmallString<128> Name;
Mang->getNameWithPrefix(Name, GV, true);
Name += "$non_lazy_ptr";
// Add information about the stub reference to MachOMMI so that the stub
// gets emitted by the asmprinter.
MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
if (StubSym.getPointer() == 0) {
MCSymbol *Sym = Mang->getSymbol(GV);
StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
}
return SSym;
}
unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const {
return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
}
unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const {
return DW_EH_PE_pcrel;
}
unsigned TargetLoweringObjectFileMachO::getFDEEncoding(bool CFI) const {
return DW_EH_PE_pcrel;
}
unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const {
return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
}
//===----------------------------------------------------------------------===//
// COFF
//===----------------------------------------------------------------------===//
void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
const TargetMachine &TM) {
TargetLoweringObjectFile::Initialize(Ctx, TM);
TextSection =
getContext().getCOFFSection(".text",
COFF::IMAGE_SCN_CNT_CODE |
COFF::IMAGE_SCN_MEM_EXECUTE |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getText());
DataSection =
getContext().getCOFFSection(".data",
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE,
SectionKind::getDataRel());
ReadOnlySection =
getContext().getCOFFSection(".rdata",
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getReadOnly());
StaticCtorSection =
getContext().getCOFFSection(".ctors",
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE,
SectionKind::getDataRel());
StaticDtorSection =
getContext().getCOFFSection(".dtors",
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE,
SectionKind::getDataRel());
// FIXME: We're emitting LSDA info into a readonly section on COFF, 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().getCOFFSection(".gcc_except_table",
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getReadOnly());
// Debug info.
DwarfAbbrevSection =
getContext().getCOFFSection(".debug_abbrev",
COFF::IMAGE_SCN_MEM_DISCARDABLE |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfInfoSection =
getContext().getCOFFSection(".debug_info",
COFF::IMAGE_SCN_MEM_DISCARDABLE |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfLineSection =
getContext().getCOFFSection(".debug_line",
COFF::IMAGE_SCN_MEM_DISCARDABLE |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfFrameSection =
getContext().getCOFFSection(".debug_frame",
COFF::IMAGE_SCN_MEM_DISCARDABLE |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfPubNamesSection =
getContext().getCOFFSection(".debug_pubnames",
COFF::IMAGE_SCN_MEM_DISCARDABLE |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfPubTypesSection =
getContext().getCOFFSection(".debug_pubtypes",
COFF::IMAGE_SCN_MEM_DISCARDABLE |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfStrSection =
getContext().getCOFFSection(".debug_str",
COFF::IMAGE_SCN_MEM_DISCARDABLE |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfLocSection =
getContext().getCOFFSection(".debug_loc",
COFF::IMAGE_SCN_MEM_DISCARDABLE |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfARangesSection =
getContext().getCOFFSection(".debug_aranges",
COFF::IMAGE_SCN_MEM_DISCARDABLE |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfRangesSection =
getContext().getCOFFSection(".debug_ranges",
COFF::IMAGE_SCN_MEM_DISCARDABLE |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfMacroInfoSection =
getContext().getCOFFSection(".debug_macinfo",
COFF::IMAGE_SCN_MEM_DISCARDABLE |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DrectveSection =
getContext().getCOFFSection(".drectve",
COFF::IMAGE_SCN_LNK_INFO,
SectionKind::getMetadata());
PDataSection =
getContext().getCOFFSection(".pdata",
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE,
SectionKind::getDataRel());
XDataSection =
getContext().getCOFFSection(".xdata",
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE,
SectionKind::getDataRel());
}
const MCSection *TargetLoweringObjectFileCOFF::getEHFrameSection() const {
return getContext().getCOFFSection(".eh_frame",
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE,
SectionKind::getDataRel());
}
static unsigned
getCOFFSectionFlags(SectionKind K) {
unsigned Flags = 0;
if (K.isMetadata())
Flags |=
COFF::IMAGE_SCN_MEM_DISCARDABLE;
else if (K.isText())
Flags |=
COFF::IMAGE_SCN_MEM_EXECUTE |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_CNT_CODE;
else if (K.isBSS ())
Flags |=
COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE;
else if (K.isReadOnly())
Flags |=
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ;
else if (K.isWriteable())
Flags |=
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE;
return Flags;
}
const MCSection *TargetLoweringObjectFileCOFF::
getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
Mangler *Mang, const TargetMachine &TM) const {
return getContext().getCOFFSection(GV->getSection(),
getCOFFSectionFlags(Kind),
Kind);
}
static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
if (Kind.isText())
return ".text$";
if (Kind.isBSS ())
return ".bss$";
if (Kind.isWriteable())
return ".data$";
return ".rdata$";
}
const MCSection *TargetLoweringObjectFileCOFF::
SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
Mangler *Mang, const TargetMachine &TM) const {
assert(!Kind.isThreadLocal() && "Doesn't support TLS");
// If this global is linkonce/weak and the target handles this by emitting it
// into a 'uniqued' section name, create and return the section now.
if (GV->isWeakForLinker()) {
const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
MCSymbol *Sym = Mang->getSymbol(GV);
Name.append(Sym->getName().begin() + 1, Sym->getName().end());
unsigned Characteristics = getCOFFSectionFlags(Kind);
Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
return getContext().getCOFFSection(Name.str(), Characteristics,
COFF::IMAGE_COMDAT_SELECT_ANY, Kind);
}
if (Kind.isText())
return getTextSection();
return getDataSection();
}
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