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llvm-mirror/lib/MC/MCObjectFileInfo.cpp
Alex Richardson 53f757e913 [MIPS][ELF] Use PC-relative relocations in .eh_frame when possible 
When compiling position-independent executables, we now use
DW_EH_PE_pcrel | DW_EH_PE_sdata4. However, the MIPS ABI does not define a
64-bit PC-relative ELF relocation so we cannot use sdata8 for the large
code model case. When using the large code model, we fall back to the
previous behaviour of generating absolute relocations.

With this change clang-generated .o files can be linked by LLD without
having to pass -Wl,-z,notext (which creates text relocations).
This is simpler than the approach used by ld.bfd, which rewrites the
.eh_frame section to convert absolute relocations into relative references.

I saw in D13104 that apparently ld.bfd did not accept pc-relative relocations
for MIPS ouput at some point. However, I also checked that recent ld.bfd
can process the clang-generated .o files so this no longer seems true.

Reviewed By: atanasyan
Differential Revision: https://reviews.llvm.org/D72228
2020-01-13 14:14:03 +00:00

894 lines
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//===-- MCObjectFileInfo.cpp - Object File Information --------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Triple.h"
#include "llvm/BinaryFormat/COFF.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/MC/MCAsmInfo.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCSectionCOFF.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCSectionWasm.h"
#include "llvm/MC/MCSectionXCOFF.h"
using namespace llvm;
static bool useCompactUnwind(const Triple &T) {
// Only on darwin.
if (!T.isOSDarwin())
return false;
// aarch64 always has it.
if (T.getArch() == Triple::aarch64 || T.getArch() == Triple::aarch64_32)
return true;
// armv7k always has it.
if (T.isWatchABI())
return true;
// Use it on newer version of OS X.
if (T.isMacOSX() && !T.isMacOSXVersionLT(10, 6))
return true;
// And the iOS simulator.
if (T.isiOS() && T.isX86())
return true;
return false;
}
void MCObjectFileInfo::initMachOMCObjectFileInfo(const Triple &T) {
// MachO
SupportsWeakOmittedEHFrame = false;
EHFrameSection = Ctx->getMachOSection(
"__TEXT", "__eh_frame",
MachO::S_COALESCED | MachO::S_ATTR_NO_TOC |
MachO::S_ATTR_STRIP_STATIC_SYMS | MachO::S_ATTR_LIVE_SUPPORT,
SectionKind::getReadOnly());
if (T.isOSDarwin() &&
(T.getArch() == Triple::aarch64 || T.getArch() == Triple::aarch64_32))
SupportsCompactUnwindWithoutEHFrame = true;
if (T.isWatchABI())
OmitDwarfIfHaveCompactUnwind = true;
FDECFIEncoding = dwarf::DW_EH_PE_pcrel;
// .comm doesn't support alignment before Leopard.
if (T.isMacOSX() && T.isMacOSXVersionLT(10, 5))
CommDirectiveSupportsAlignment = false;
TextSection // .text
= Ctx->getMachOSection("__TEXT", "__text",
MachO::S_ATTR_PURE_INSTRUCTIONS,
SectionKind::getText());
DataSection // .data
= Ctx->getMachOSection("__DATA", "__data", 0, SectionKind::getData());
// BSSSection might not be expected initialized on msvc.
BSSSection = nullptr;
TLSDataSection // .tdata
= Ctx->getMachOSection("__DATA", "__thread_data",
MachO::S_THREAD_LOCAL_REGULAR,
SectionKind::getData());
TLSBSSSection // .tbss
= Ctx->getMachOSection("__DATA", "__thread_bss",
MachO::S_THREAD_LOCAL_ZEROFILL,
SectionKind::getThreadBSS());
// TODO: Verify datarel below.
TLSTLVSection // .tlv
= Ctx->getMachOSection("__DATA", "__thread_vars",
MachO::S_THREAD_LOCAL_VARIABLES,
SectionKind::getData());
TLSThreadInitSection = Ctx->getMachOSection(
"__DATA", "__thread_init", MachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
SectionKind::getData());
CStringSection // .cstring
= Ctx->getMachOSection("__TEXT", "__cstring",
MachO::S_CSTRING_LITERALS,
SectionKind::getMergeable1ByteCString());
UStringSection
= Ctx->getMachOSection("__TEXT","__ustring", 0,
SectionKind::getMergeable2ByteCString());
FourByteConstantSection // .literal4
= Ctx->getMachOSection("__TEXT", "__literal4",
MachO::S_4BYTE_LITERALS,
SectionKind::getMergeableConst4());
EightByteConstantSection // .literal8
= Ctx->getMachOSection("__TEXT", "__literal8",
MachO::S_8BYTE_LITERALS,
SectionKind::getMergeableConst8());
SixteenByteConstantSection // .literal16
= Ctx->getMachOSection("__TEXT", "__literal16",
MachO::S_16BYTE_LITERALS,
SectionKind::getMergeableConst16());
ReadOnlySection // .const
= Ctx->getMachOSection("__TEXT", "__const", 0,
SectionKind::getReadOnly());
// If the target is not powerpc, map the coal sections to the non-coal
// sections.
//
// "__TEXT/__textcoal_nt" => section "__TEXT/__text"
// "__TEXT/__const_coal" => section "__TEXT/__const"
// "__DATA/__datacoal_nt" => section "__DATA/__data"
Triple::ArchType ArchTy = T.getArch();
ConstDataSection // .const_data
= Ctx->getMachOSection("__DATA", "__const", 0,
SectionKind::getReadOnlyWithRel());
if (ArchTy == Triple::ppc || ArchTy == Triple::ppc64) {
TextCoalSection
= Ctx->getMachOSection("__TEXT", "__textcoal_nt",
MachO::S_COALESCED |
MachO::S_ATTR_PURE_INSTRUCTIONS,
SectionKind::getText());
ConstTextCoalSection
= Ctx->getMachOSection("__TEXT", "__const_coal",
MachO::S_COALESCED,
SectionKind::getReadOnly());
DataCoalSection = Ctx->getMachOSection(
"__DATA", "__datacoal_nt", MachO::S_COALESCED, SectionKind::getData());
ConstDataCoalSection = DataCoalSection;
} else {
TextCoalSection = TextSection;
ConstTextCoalSection = ReadOnlySection;
DataCoalSection = DataSection;
ConstDataCoalSection = ConstDataSection;
}
DataCommonSection
= Ctx->getMachOSection("__DATA","__common",
MachO::S_ZEROFILL,
SectionKind::getBSS());
DataBSSSection
= Ctx->getMachOSection("__DATA","__bss", MachO::S_ZEROFILL,
SectionKind::getBSS());
LazySymbolPointerSection
= Ctx->getMachOSection("__DATA", "__la_symbol_ptr",
MachO::S_LAZY_SYMBOL_POINTERS,
SectionKind::getMetadata());
NonLazySymbolPointerSection
= Ctx->getMachOSection("__DATA", "__nl_symbol_ptr",
MachO::S_NON_LAZY_SYMBOL_POINTERS,
SectionKind::getMetadata());
ThreadLocalPointerSection
= Ctx->getMachOSection("__DATA", "__thread_ptr",
MachO::S_THREAD_LOCAL_VARIABLE_POINTERS,
SectionKind::getMetadata());
// Exception Handling.
LSDASection = Ctx->getMachOSection("__TEXT", "__gcc_except_tab", 0,
SectionKind::getReadOnlyWithRel());
COFFDebugSymbolsSection = nullptr;
COFFDebugTypesSection = nullptr;
COFFGlobalTypeHashesSection = nullptr;
if (useCompactUnwind(T)) {
CompactUnwindSection =
Ctx->getMachOSection("__LD", "__compact_unwind", MachO::S_ATTR_DEBUG,
SectionKind::getReadOnly());
if (T.isX86())
CompactUnwindDwarfEHFrameOnly = 0x04000000; // UNWIND_X86_64_MODE_DWARF
else if (T.getArch() == Triple::aarch64 || T.getArch() == Triple::aarch64_32)
CompactUnwindDwarfEHFrameOnly = 0x03000000; // UNWIND_ARM64_MODE_DWARF
else if (T.getArch() == Triple::arm || T.getArch() == Triple::thumb)
CompactUnwindDwarfEHFrameOnly = 0x04000000; // UNWIND_ARM_MODE_DWARF
}
// Debug Information.
DwarfDebugNamesSection =
Ctx->getMachOSection("__DWARF", "__debug_names", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "debug_names_begin");
DwarfAccelNamesSection =
Ctx->getMachOSection("__DWARF", "__apple_names", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "names_begin");
DwarfAccelObjCSection =
Ctx->getMachOSection("__DWARF", "__apple_objc", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "objc_begin");
// 16 character section limit...
DwarfAccelNamespaceSection =
Ctx->getMachOSection("__DWARF", "__apple_namespac", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "namespac_begin");
DwarfAccelTypesSection =
Ctx->getMachOSection("__DWARF", "__apple_types", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "types_begin");
DwarfSwiftASTSection =
Ctx->getMachOSection("__DWARF", "__swift_ast", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfAbbrevSection =
Ctx->getMachOSection("__DWARF", "__debug_abbrev", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "section_abbrev");
DwarfInfoSection =
Ctx->getMachOSection("__DWARF", "__debug_info", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "section_info");
DwarfLineSection =
Ctx->getMachOSection("__DWARF", "__debug_line", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "section_line");
DwarfLineStrSection =
Ctx->getMachOSection("__DWARF", "__debug_line_str", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "section_line_str");
DwarfFrameSection =
Ctx->getMachOSection("__DWARF", "__debug_frame", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfPubNamesSection =
Ctx->getMachOSection("__DWARF", "__debug_pubnames", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfPubTypesSection =
Ctx->getMachOSection("__DWARF", "__debug_pubtypes", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfGnuPubNamesSection =
Ctx->getMachOSection("__DWARF", "__debug_gnu_pubn", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfGnuPubTypesSection =
Ctx->getMachOSection("__DWARF", "__debug_gnu_pubt", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfStrSection =
Ctx->getMachOSection("__DWARF", "__debug_str", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "info_string");
DwarfStrOffSection =
Ctx->getMachOSection("__DWARF", "__debug_str_offs", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "section_str_off");
DwarfAddrSection =
Ctx->getMachOSection("__DWARF", "__debug_addr", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "section_info");
DwarfLocSection =
Ctx->getMachOSection("__DWARF", "__debug_loc", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "section_debug_loc");
DwarfLoclistsSection =
Ctx->getMachOSection("__DWARF", "__debug_loclists", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "section_debug_loc");
DwarfARangesSection =
Ctx->getMachOSection("__DWARF", "__debug_aranges", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfRangesSection =
Ctx->getMachOSection("__DWARF", "__debug_ranges", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "debug_range");
DwarfRnglistsSection =
Ctx->getMachOSection("__DWARF", "__debug_rnglists", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "debug_range");
DwarfMacinfoSection =
Ctx->getMachOSection("__DWARF", "__debug_macinfo", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata(), "debug_macinfo");
DwarfDebugInlineSection =
Ctx->getMachOSection("__DWARF", "__debug_inlined", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfCUIndexSection =
Ctx->getMachOSection("__DWARF", "__debug_cu_index", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
DwarfTUIndexSection =
Ctx->getMachOSection("__DWARF", "__debug_tu_index", MachO::S_ATTR_DEBUG,
SectionKind::getMetadata());
StackMapSection = Ctx->getMachOSection("__LLVM_STACKMAPS", "__llvm_stackmaps",
0, SectionKind::getMetadata());
FaultMapSection = Ctx->getMachOSection("__LLVM_FAULTMAPS", "__llvm_faultmaps",
0, SectionKind::getMetadata());
RemarksSection = Ctx->getMachOSection(
"__LLVM", "__remarks", MachO::S_ATTR_DEBUG, SectionKind::getMetadata());
TLSExtraDataSection = TLSTLVSection;
}
void MCObjectFileInfo::initELFMCObjectFileInfo(const Triple &T, bool Large) {
switch (T.getArch()) {
case Triple::mips:
case Triple::mipsel:
case Triple::mips64:
case Triple::mips64el:
// We cannot use DW_EH_PE_sdata8 for the large PositionIndependent case
// since there is no R_MIPS_PC64 relocation (only a 32-bit version).
if (PositionIndependent && !Large)
FDECFIEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
else
FDECFIEncoding = Ctx->getAsmInfo()->getCodePointerSize() == 4
? dwarf::DW_EH_PE_sdata4
: dwarf::DW_EH_PE_sdata8;
break;
case Triple::ppc64:
case Triple::ppc64le:
case Triple::x86_64:
FDECFIEncoding = dwarf::DW_EH_PE_pcrel |
(Large ? dwarf::DW_EH_PE_sdata8 : dwarf::DW_EH_PE_sdata4);
break;
case Triple::bpfel:
case Triple::bpfeb:
FDECFIEncoding = dwarf::DW_EH_PE_sdata8;
break;
case Triple::hexagon:
FDECFIEncoding =
PositionIndependent ? dwarf::DW_EH_PE_pcrel : dwarf::DW_EH_PE_absptr;
break;
default:
FDECFIEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
break;
}
unsigned EHSectionType = T.getArch() == Triple::x86_64
? ELF::SHT_X86_64_UNWIND
: ELF::SHT_PROGBITS;
// Solaris requires different flags for .eh_frame to seemingly every other
// platform.
unsigned EHSectionFlags = ELF::SHF_ALLOC;
if (T.isOSSolaris() && T.getArch() != Triple::x86_64)
EHSectionFlags |= ELF::SHF_WRITE;
// ELF
BSSSection = Ctx->getELFSection(".bss", ELF::SHT_NOBITS,
ELF::SHF_WRITE | ELF::SHF_ALLOC);
TextSection = Ctx->getELFSection(".text", ELF::SHT_PROGBITS,
ELF::SHF_EXECINSTR | ELF::SHF_ALLOC);
DataSection = Ctx->getELFSection(".data", ELF::SHT_PROGBITS,
ELF::SHF_WRITE | ELF::SHF_ALLOC);
ReadOnlySection =
Ctx->getELFSection(".rodata", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
TLSDataSection =
Ctx->getELFSection(".tdata", ELF::SHT_PROGBITS,
ELF::SHF_ALLOC | ELF::SHF_TLS | ELF::SHF_WRITE);
TLSBSSSection = Ctx->getELFSection(
".tbss", ELF::SHT_NOBITS, ELF::SHF_ALLOC | ELF::SHF_TLS | ELF::SHF_WRITE);
DataRelROSection = Ctx->getELFSection(".data.rel.ro", ELF::SHT_PROGBITS,
ELF::SHF_ALLOC | ELF::SHF_WRITE);
MergeableConst4Section =
Ctx->getELFSection(".rodata.cst4", ELF::SHT_PROGBITS,
ELF::SHF_ALLOC | ELF::SHF_MERGE, 4, "");
MergeableConst8Section =
Ctx->getELFSection(".rodata.cst8", ELF::SHT_PROGBITS,
ELF::SHF_ALLOC | ELF::SHF_MERGE, 8, "");
MergeableConst16Section =
Ctx->getELFSection(".rodata.cst16", ELF::SHT_PROGBITS,
ELF::SHF_ALLOC | ELF::SHF_MERGE, 16, "");
MergeableConst32Section =
Ctx->getELFSection(".rodata.cst32", ELF::SHT_PROGBITS,
ELF::SHF_ALLOC | ELF::SHF_MERGE, 32, "");
// 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 = Ctx->getELFSection(".gcc_except_table", ELF::SHT_PROGBITS,
ELF::SHF_ALLOC);
COFFDebugSymbolsSection = nullptr;
COFFDebugTypesSection = nullptr;
unsigned DebugSecType = ELF::SHT_PROGBITS;
// MIPS .debug_* sections should have SHT_MIPS_DWARF section type
// to distinguish among sections contain DWARF and ECOFF debug formats.
// Sections with ECOFF debug format are obsoleted and marked by SHT_PROGBITS.
if (T.isMIPS())
DebugSecType = ELF::SHT_MIPS_DWARF;
// Debug Info Sections.
DwarfAbbrevSection =
Ctx->getELFSection(".debug_abbrev", DebugSecType, 0);
DwarfInfoSection = Ctx->getELFSection(".debug_info", DebugSecType, 0);
DwarfLineSection = Ctx->getELFSection(".debug_line", DebugSecType, 0);
DwarfLineStrSection =
Ctx->getELFSection(".debug_line_str", DebugSecType,
ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
DwarfFrameSection = Ctx->getELFSection(".debug_frame", DebugSecType, 0);
DwarfPubNamesSection =
Ctx->getELFSection(".debug_pubnames", DebugSecType, 0);
DwarfPubTypesSection =
Ctx->getELFSection(".debug_pubtypes", DebugSecType, 0);
DwarfGnuPubNamesSection =
Ctx->getELFSection(".debug_gnu_pubnames", DebugSecType, 0);
DwarfGnuPubTypesSection =
Ctx->getELFSection(".debug_gnu_pubtypes", DebugSecType, 0);
DwarfStrSection =
Ctx->getELFSection(".debug_str", DebugSecType,
ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
DwarfLocSection = Ctx->getELFSection(".debug_loc", DebugSecType, 0);
DwarfARangesSection =
Ctx->getELFSection(".debug_aranges", DebugSecType, 0);
DwarfRangesSection =
Ctx->getELFSection(".debug_ranges", DebugSecType, 0);
DwarfMacinfoSection =
Ctx->getELFSection(".debug_macinfo", DebugSecType, 0);
// DWARF5 Experimental Debug Info
// Accelerator Tables
DwarfDebugNamesSection =
Ctx->getELFSection(".debug_names", ELF::SHT_PROGBITS, 0);
DwarfAccelNamesSection =
Ctx->getELFSection(".apple_names", ELF::SHT_PROGBITS, 0);
DwarfAccelObjCSection =
Ctx->getELFSection(".apple_objc", ELF::SHT_PROGBITS, 0);
DwarfAccelNamespaceSection =
Ctx->getELFSection(".apple_namespaces", ELF::SHT_PROGBITS, 0);
DwarfAccelTypesSection =
Ctx->getELFSection(".apple_types", ELF::SHT_PROGBITS, 0);
// String Offset and Address Sections
DwarfStrOffSection =
Ctx->getELFSection(".debug_str_offsets", DebugSecType, 0);
DwarfAddrSection = Ctx->getELFSection(".debug_addr", DebugSecType, 0);
DwarfRnglistsSection = Ctx->getELFSection(".debug_rnglists", DebugSecType, 0);
DwarfLoclistsSection = Ctx->getELFSection(".debug_loclists", DebugSecType, 0);
// Fission Sections
DwarfInfoDWOSection =
Ctx->getELFSection(".debug_info.dwo", DebugSecType, ELF::SHF_EXCLUDE);
DwarfTypesDWOSection =
Ctx->getELFSection(".debug_types.dwo", DebugSecType, ELF::SHF_EXCLUDE);
DwarfAbbrevDWOSection =
Ctx->getELFSection(".debug_abbrev.dwo", DebugSecType, ELF::SHF_EXCLUDE);
DwarfStrDWOSection = Ctx->getELFSection(
".debug_str.dwo", DebugSecType,
ELF::SHF_MERGE | ELF::SHF_STRINGS | ELF::SHF_EXCLUDE, 1, "");
DwarfLineDWOSection =
Ctx->getELFSection(".debug_line.dwo", DebugSecType, ELF::SHF_EXCLUDE);
DwarfLocDWOSection =
Ctx->getELFSection(".debug_loc.dwo", DebugSecType, ELF::SHF_EXCLUDE);
DwarfStrOffDWOSection = Ctx->getELFSection(".debug_str_offsets.dwo",
DebugSecType, ELF::SHF_EXCLUDE);
DwarfRnglistsDWOSection =
Ctx->getELFSection(".debug_rnglists.dwo", DebugSecType, ELF::SHF_EXCLUDE);
DwarfMacinfoDWOSection =
Ctx->getELFSection(".debug_macinfo.dwo", DebugSecType, ELF::SHF_EXCLUDE);
DwarfLoclistsDWOSection =
Ctx->getELFSection(".debug_loclists.dwo", DebugSecType, ELF::SHF_EXCLUDE);
// DWP Sections
DwarfCUIndexSection =
Ctx->getELFSection(".debug_cu_index", DebugSecType, 0);
DwarfTUIndexSection =
Ctx->getELFSection(".debug_tu_index", DebugSecType, 0);
StackMapSection =
Ctx->getELFSection(".llvm_stackmaps", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
FaultMapSection =
Ctx->getELFSection(".llvm_faultmaps", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
EHFrameSection =
Ctx->getELFSection(".eh_frame", EHSectionType, EHSectionFlags);
StackSizesSection = Ctx->getELFSection(".stack_sizes", ELF::SHT_PROGBITS, 0);
}
void MCObjectFileInfo::initCOFFMCObjectFileInfo(const Triple &T) {
EHFrameSection =
Ctx->getCOFFSection(".eh_frame", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getData());
// Set the `IMAGE_SCN_MEM_16BIT` flag when compiling for thumb mode. This is
// used to indicate to the linker that the text segment contains thumb instructions
// and to set the ISA selection bit for calls accordingly.
const bool IsThumb = T.getArch() == Triple::thumb;
CommDirectiveSupportsAlignment = true;
// COFF
BSSSection = Ctx->getCOFFSection(
".bss", COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
SectionKind::getBSS());
TextSection = Ctx->getCOFFSection(
".text",
(IsThumb ? COFF::IMAGE_SCN_MEM_16BIT : (COFF::SectionCharacteristics)0) |
COFF::IMAGE_SCN_CNT_CODE | COFF::IMAGE_SCN_MEM_EXECUTE |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getText());
DataSection = Ctx->getCOFFSection(
".data", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE,
SectionKind::getData());
ReadOnlySection = Ctx->getCOFFSection(
".rdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
SectionKind::getReadOnly());
if (T.getArch() == Triple::x86_64 || T.getArch() == Triple::aarch64) {
// On Windows 64 with SEH, the LSDA is emitted into the .xdata section
LSDASection = nullptr;
} else {
LSDASection = Ctx->getCOFFSection(".gcc_except_table",
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getReadOnly());
}
// Debug info.
COFFDebugSymbolsSection =
Ctx->getCOFFSection(".debug$S", (COFF::IMAGE_SCN_MEM_DISCARDABLE |
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ),
SectionKind::getMetadata());
COFFDebugTypesSection =
Ctx->getCOFFSection(".debug$T", (COFF::IMAGE_SCN_MEM_DISCARDABLE |
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ),
SectionKind::getMetadata());
COFFGlobalTypeHashesSection = Ctx->getCOFFSection(
".debug$H",
(COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ),
SectionKind::getMetadata());
DwarfAbbrevSection = Ctx->getCOFFSection(
".debug_abbrev",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "section_abbrev");
DwarfInfoSection = Ctx->getCOFFSection(
".debug_info",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "section_info");
DwarfLineSection = Ctx->getCOFFSection(
".debug_line",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "section_line");
DwarfLineStrSection = Ctx->getCOFFSection(
".debug_line_str",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "section_line_str");
DwarfFrameSection = Ctx->getCOFFSection(
".debug_frame",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfPubNamesSection = Ctx->getCOFFSection(
".debug_pubnames",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfPubTypesSection = Ctx->getCOFFSection(
".debug_pubtypes",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfGnuPubNamesSection = Ctx->getCOFFSection(
".debug_gnu_pubnames",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfGnuPubTypesSection = Ctx->getCOFFSection(
".debug_gnu_pubtypes",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfStrSection = Ctx->getCOFFSection(
".debug_str",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "info_string");
DwarfStrOffSection = Ctx->getCOFFSection(
".debug_str_offsets",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "section_str_off");
DwarfLocSection = Ctx->getCOFFSection(
".debug_loc",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "section_debug_loc");
DwarfARangesSection = Ctx->getCOFFSection(
".debug_aranges",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfRangesSection = Ctx->getCOFFSection(
".debug_ranges",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "debug_range");
DwarfMacinfoSection = Ctx->getCOFFSection(
".debug_macinfo",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "debug_macinfo");
DwarfMacinfoDWOSection = Ctx->getCOFFSection(
".debug_macinfo.dwo",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "debug_macinfo.dwo");
DwarfInfoDWOSection = Ctx->getCOFFSection(
".debug_info.dwo",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "section_info_dwo");
DwarfTypesDWOSection = Ctx->getCOFFSection(
".debug_types.dwo",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "section_types_dwo");
DwarfAbbrevDWOSection = Ctx->getCOFFSection(
".debug_abbrev.dwo",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "section_abbrev_dwo");
DwarfStrDWOSection = Ctx->getCOFFSection(
".debug_str.dwo",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "skel_string");
DwarfLineDWOSection = Ctx->getCOFFSection(
".debug_line.dwo",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfLocDWOSection = Ctx->getCOFFSection(
".debug_loc.dwo",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "skel_loc");
DwarfStrOffDWOSection = Ctx->getCOFFSection(
".debug_str_offsets.dwo",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "section_str_off_dwo");
DwarfAddrSection = Ctx->getCOFFSection(
".debug_addr",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "addr_sec");
DwarfCUIndexSection = Ctx->getCOFFSection(
".debug_cu_index",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfTUIndexSection = Ctx->getCOFFSection(
".debug_tu_index",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
DwarfDebugNamesSection = Ctx->getCOFFSection(
".debug_names",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "debug_names_begin");
DwarfAccelNamesSection = Ctx->getCOFFSection(
".apple_names",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "names_begin");
DwarfAccelNamespaceSection = Ctx->getCOFFSection(
".apple_namespaces",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "namespac_begin");
DwarfAccelTypesSection = Ctx->getCOFFSection(
".apple_types",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "types_begin");
DwarfAccelObjCSection = Ctx->getCOFFSection(
".apple_objc",
COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata(), "objc_begin");
DrectveSection = Ctx->getCOFFSection(
".drectve", COFF::IMAGE_SCN_LNK_INFO | COFF::IMAGE_SCN_LNK_REMOVE,
SectionKind::getMetadata());
PDataSection = Ctx->getCOFFSection(
".pdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
SectionKind::getData());
XDataSection = Ctx->getCOFFSection(
".xdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
SectionKind::getData());
SXDataSection = Ctx->getCOFFSection(".sxdata", COFF::IMAGE_SCN_LNK_INFO,
SectionKind::getMetadata());
GFIDsSection = Ctx->getCOFFSection(".gfids$y",
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
GLJMPSection = Ctx->getCOFFSection(".gljmp$y",
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getMetadata());
TLSDataSection = Ctx->getCOFFSection(
".tls$", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
COFF::IMAGE_SCN_MEM_WRITE,
SectionKind::getData());
StackMapSection = Ctx->getCOFFSection(".llvm_stackmaps",
COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
COFF::IMAGE_SCN_MEM_READ,
SectionKind::getReadOnly());
}
void MCObjectFileInfo::initWasmMCObjectFileInfo(const Triple &T) {
TextSection = Ctx->getWasmSection(".text", SectionKind::getText());
DataSection = Ctx->getWasmSection(".data", SectionKind::getData());
DwarfLineSection =
Ctx->getWasmSection(".debug_line", SectionKind::getMetadata());
DwarfLineStrSection =
Ctx->getWasmSection(".debug_line_str", SectionKind::getMetadata());
DwarfStrSection =
Ctx->getWasmSection(".debug_str", SectionKind::getMetadata());
DwarfLocSection =
Ctx->getWasmSection(".debug_loc", SectionKind::getMetadata());
DwarfAbbrevSection =
Ctx->getWasmSection(".debug_abbrev", SectionKind::getMetadata());
DwarfARangesSection = Ctx->getWasmSection(".debug_aranges", SectionKind::getMetadata());
DwarfRangesSection =
Ctx->getWasmSection(".debug_ranges", SectionKind::getMetadata());
DwarfMacinfoSection =
Ctx->getWasmSection(".debug_macinfo", SectionKind::getMetadata());
DwarfAddrSection = Ctx->getWasmSection(".debug_addr", SectionKind::getMetadata());
DwarfCUIndexSection = Ctx->getWasmSection(".debug_cu_index", SectionKind::getMetadata());
DwarfTUIndexSection = Ctx->getWasmSection(".debug_tu_index", SectionKind::getMetadata());
DwarfInfoSection =
Ctx->getWasmSection(".debug_info", SectionKind::getMetadata());
DwarfFrameSection = Ctx->getWasmSection(".debug_frame", SectionKind::getMetadata());
DwarfPubNamesSection = Ctx->getWasmSection(".debug_pubnames", SectionKind::getMetadata());
DwarfPubTypesSection = Ctx->getWasmSection(".debug_pubtypes", SectionKind::getMetadata());
// Wasm use data section for LSDA.
// TODO Consider putting each function's exception table in a separate
// section, as in -function-sections, to facilitate lld's --gc-section.
LSDASection = Ctx->getWasmSection(".rodata.gcc_except_table",
SectionKind::getReadOnlyWithRel());
// TODO: Define more sections.
}
void MCObjectFileInfo::initXCOFFMCObjectFileInfo(const Triple &T) {
// The default csect for program code. Functions without a specified section
// get placed into this csect. The choice of csect name is not a property of
// the ABI or object file format. For example, the XL compiler uses an unnamed
// csect for program code.
TextSection = Ctx->getXCOFFSection(
".text", XCOFF::StorageMappingClass::XMC_PR, XCOFF::XTY_SD,
XCOFF::C_HIDEXT, SectionKind::getText());
DataSection = Ctx->getXCOFFSection(
".data", XCOFF::StorageMappingClass::XMC_RW, XCOFF::XTY_SD,
XCOFF::C_HIDEXT, SectionKind::getData());
ReadOnlySection = Ctx->getXCOFFSection(
".rodata", XCOFF::StorageMappingClass::XMC_RO, XCOFF::XTY_SD,
XCOFF::C_HIDEXT, SectionKind::getReadOnly());
}
void MCObjectFileInfo::InitMCObjectFileInfo(const Triple &TheTriple, bool PIC,
MCContext &ctx,
bool LargeCodeModel) {
PositionIndependent = PIC;
Ctx = &ctx;
// Common.
CommDirectiveSupportsAlignment = true;
SupportsWeakOmittedEHFrame = true;
SupportsCompactUnwindWithoutEHFrame = false;
OmitDwarfIfHaveCompactUnwind = false;
FDECFIEncoding = dwarf::DW_EH_PE_absptr;
CompactUnwindDwarfEHFrameOnly = 0;
EHFrameSection = nullptr; // Created on demand.
CompactUnwindSection = nullptr; // Used only by selected targets.
DwarfAccelNamesSection = nullptr; // Used only by selected targets.
DwarfAccelObjCSection = nullptr; // Used only by selected targets.
DwarfAccelNamespaceSection = nullptr; // Used only by selected targets.
DwarfAccelTypesSection = nullptr; // Used only by selected targets.
TT = TheTriple;
switch (TT.getObjectFormat()) {
case Triple::MachO:
Env = IsMachO;
initMachOMCObjectFileInfo(TT);
break;
case Triple::COFF:
if (!TT.isOSWindows())
report_fatal_error(
"Cannot initialize MC for non-Windows COFF object files.");
Env = IsCOFF;
initCOFFMCObjectFileInfo(TT);
break;
case Triple::ELF:
Env = IsELF;
initELFMCObjectFileInfo(TT, LargeCodeModel);
break;
case Triple::Wasm:
Env = IsWasm;
initWasmMCObjectFileInfo(TT);
break;
case Triple::XCOFF:
Env = IsXCOFF;
initXCOFFMCObjectFileInfo(TT);
break;
case Triple::UnknownObjectFormat:
report_fatal_error("Cannot initialize MC for unknown object file format.");
break;
}
}
MCSection *MCObjectFileInfo::getDwarfComdatSection(const char *Name,
uint64_t Hash) const {
switch (TT.getObjectFormat()) {
case Triple::ELF:
return Ctx->getELFSection(Name, ELF::SHT_PROGBITS, ELF::SHF_GROUP, 0,
utostr(Hash));
case Triple::MachO:
case Triple::COFF:
case Triple::Wasm:
case Triple::XCOFF:
case Triple::UnknownObjectFormat:
report_fatal_error("Cannot get DWARF comdat section for this object file "
"format: not implemented.");
break;
}
llvm_unreachable("Unknown ObjectFormatType");
}
MCSection *
MCObjectFileInfo::getStackSizesSection(const MCSection &TextSec) const {
if (Env != IsELF)
return StackSizesSection;
const MCSectionELF &ElfSec = static_cast<const MCSectionELF &>(TextSec);
unsigned Flags = ELF::SHF_LINK_ORDER;
StringRef GroupName;
if (const MCSymbol *Group = ElfSec.getGroup()) {
GroupName = Group->getName();
Flags |= ELF::SHF_GROUP;
}
const MCSymbol *Link = TextSec.getBeginSymbol();
auto It = StackSizesUniquing.insert({Link, StackSizesUniquing.size()});
unsigned UniqueID = It.first->second;
return Ctx->getELFSection(".stack_sizes", ELF::SHT_PROGBITS, Flags, 0,
GroupName, UniqueID, cast<MCSymbolELF>(Link));
}
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