lib/MC/MCObjectFileInfo.cpp

   1 //===-- MObjectFileInfo.cpp - Object File Information ---------------------===//
   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/MCObjectFileInfo.h"
  11 #include "llvm/ADT/StringExtras.h"
  12 #include "llvm/ADT/Triple.h"
  13 #include "llvm/MC/MCAsmInfo.h"
  14 #include "llvm/MC/MCContext.h"
  15 #include "llvm/MC/MCSection.h"
  16 #include "llvm/MC/MCSectionCOFF.h"
  17 #include "llvm/MC/MCSectionELF.h"
  18 #include "llvm/MC/MCSectionMachO.h"
  19 using namespace llvm;
  20
  21 static bool useCompactUnwind(const Triple &T) {
  22   // Only on darwin.
  23   if (!T.isOSDarwin())
  24     return false;
  25
  26   // aarch64 always has it.
  27   if (T.getArch() == Triple::aarch64)
  28     return true;
  29
  30   // Use it on newer version of OS X.
  31   if (T.isMacOSX() && !T.isMacOSXVersionLT(10, 6))
  32     return true;
  33
  34   // And the iOS simulator.
  35   if (T.isiOS() &&
  36       (T.getArch() == Triple::x86_64 || T.getArch() == Triple::x86))
  37     return true;
  38
  39   return false;
  40 }
  41
  42 void MCObjectFileInfo::InitMachOMCObjectFileInfo(Triple T) {
  43   // MachO
  44   SupportsWeakOmittedEHFrame = false;
  45
  46   if (T.isOSDarwin() && T.getArch() == Triple::aarch64)
  47     SupportsCompactUnwindWithoutEHFrame = true;
  48
  49   PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel
  50     | dwarf::DW_EH_PE_sdata4;
  51   LSDAEncoding = FDECFIEncoding = dwarf::DW_EH_PE_pcrel;
  52   TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
  53     dwarf::DW_EH_PE_sdata4;
  54
  55   // .comm doesn't support alignment before Leopard.
  56   if (T.isMacOSX() && T.isMacOSXVersionLT(10, 5))
  57     CommDirectiveSupportsAlignment = false;
  58
  59   TextSection // .text
  60     = Ctx->getMachOSection("__TEXT", "__text",
  61                            MachO::S_ATTR_PURE_INSTRUCTIONS,
  62                            SectionKind::getText());
  63   DataSection // .data
  64     = Ctx->getMachOSection("__DATA", "__data", 0,
  65                            SectionKind::getDataRel());
  66
  67   // BSSSection might not be expected initialized on msvc.
  68   BSSSection = nullptr;
  69
  70   TLSDataSection // .tdata
  71     = Ctx->getMachOSection("__DATA", "__thread_data",
  72                            MachO::S_THREAD_LOCAL_REGULAR,
  73                            SectionKind::getDataRel());
  74   TLSBSSSection // .tbss
  75     = Ctx->getMachOSection("__DATA", "__thread_bss",
  76                            MachO::S_THREAD_LOCAL_ZEROFILL,
  77                            SectionKind::getThreadBSS());
  78
  79   // TODO: Verify datarel below.
  80   TLSTLVSection // .tlv
  81     = Ctx->getMachOSection("__DATA", "__thread_vars",
  82                            MachO::S_THREAD_LOCAL_VARIABLES,
  83                            SectionKind::getDataRel());
  84
  85   TLSThreadInitSection
  86     = Ctx->getMachOSection("__DATA", "__thread_init",
  87                           MachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
  88                           SectionKind::getDataRel());
  89
  90   CStringSection // .cstring
  91     = Ctx->getMachOSection("__TEXT", "__cstring",
  92                            MachO::S_CSTRING_LITERALS,
  93                            SectionKind::getMergeable1ByteCString());
  94   UStringSection
  95     = Ctx->getMachOSection("__TEXT","__ustring", 0,
  96                            SectionKind::getMergeable2ByteCString());
  97   FourByteConstantSection // .literal4
  98     = Ctx->getMachOSection("__TEXT", "__literal4",
  99                            MachO::S_4BYTE_LITERALS,
 100                            SectionKind::getMergeableConst4());
 101   EightByteConstantSection // .literal8
 102     = Ctx->getMachOSection("__TEXT", "__literal8",
 103                            MachO::S_8BYTE_LITERALS,
 104                            SectionKind::getMergeableConst8());
 105
 106   SixteenByteConstantSection // .literal16
 107       = Ctx->getMachOSection("__TEXT", "__literal16",
 108                              MachO::S_16BYTE_LITERALS,
 109                              SectionKind::getMergeableConst16());
 110
 111   ReadOnlySection  // .const
 112     = Ctx->getMachOSection("__TEXT", "__const", 0,
 113                            SectionKind::getReadOnly());
 114
 115   TextCoalSection
 116     = Ctx->getMachOSection("__TEXT", "__textcoal_nt",
 117                            MachO::S_COALESCED |
 118                            MachO::S_ATTR_PURE_INSTRUCTIONS,
 119                            SectionKind::getText());
 120   ConstTextCoalSection
 121     = Ctx->getMachOSection("__TEXT", "__const_coal",
 122                            MachO::S_COALESCED,
 123                            SectionKind::getReadOnly());
 124   ConstDataSection  // .const_data
 125     = Ctx->getMachOSection("__DATA", "__const", 0,
 126                            SectionKind::getReadOnlyWithRel());
 127   DataCoalSection
 128     = Ctx->getMachOSection("__DATA","__datacoal_nt",
 129                            MachO::S_COALESCED,
 130                            SectionKind::getDataRel());
 131   DataCommonSection
 132     = Ctx->getMachOSection("__DATA","__common",
 133                            MachO::S_ZEROFILL,
 134                            SectionKind::getBSS());
 135   DataBSSSection
 136     = Ctx->getMachOSection("__DATA","__bss", MachO::S_ZEROFILL,
 137                            SectionKind::getBSS());
 138
 139
 140   LazySymbolPointerSection
 141     = Ctx->getMachOSection("__DATA", "__la_symbol_ptr",
 142                            MachO::S_LAZY_SYMBOL_POINTERS,
 143                            SectionKind::getMetadata());
 144   NonLazySymbolPointerSection
 145     = Ctx->getMachOSection("__DATA", "__nl_symbol_ptr",
 146                            MachO::S_NON_LAZY_SYMBOL_POINTERS,
 147                            SectionKind::getMetadata());
 148
 149   if (RelocM == Reloc::Static) {
 150     StaticCtorSection
 151       = Ctx->getMachOSection("__TEXT", "__constructor", 0,
 152                              SectionKind::getDataRel());
 153     StaticDtorSection
 154       = Ctx->getMachOSection("__TEXT", "__destructor", 0,
 155                              SectionKind::getDataRel());
 156   } else {
 157     StaticCtorSection
 158       = Ctx->getMachOSection("__DATA", "__mod_init_func",
 159                              MachO::S_MOD_INIT_FUNC_POINTERS,
 160                              SectionKind::getDataRel());
 161     StaticDtorSection
 162       = Ctx->getMachOSection("__DATA", "__mod_term_func",
 163                              MachO::S_MOD_TERM_FUNC_POINTERS,
 164                              SectionKind::getDataRel());
 165   }
 166
 167   // Exception Handling.
 168   LSDASection = Ctx->getMachOSection("__TEXT", "__gcc_except_tab", 0,
 169                                      SectionKind::getReadOnlyWithRel());
 170
 171   COFFDebugSymbolsSection = nullptr;
 172
 173   if (useCompactUnwind(T)) {
 174     CompactUnwindSection =
 175         Ctx->getMachOSection("__LD", "__compact_unwind", MachO::S_ATTR_DEBUG,
 176                              SectionKind::getReadOnly());
 177
 178     if (T.getArch() == Triple::x86_64 || T.getArch() == Triple::x86)
 179       CompactUnwindDwarfEHFrameOnly = 0x04000000;
 180     else if (T.getArch() == Triple::aarch64)
 181       CompactUnwindDwarfEHFrameOnly = 0x03000000;
 182   }
 183
 184   // Debug Information.
 185   DwarfAccelNamesSection =
 186       Ctx->getMachOSection("__DWARF", "__apple_names", MachO::S_ATTR_DEBUG,
 187                            SectionKind::getMetadata(), "names_begin");
 188   DwarfAccelObjCSection =
 189       Ctx->getMachOSection("__DWARF", "__apple_objc", MachO::S_ATTR_DEBUG,
 190                            SectionKind::getMetadata(), "objc_begin");
 191   // 16 character section limit...
 192   DwarfAccelNamespaceSection =
 193       Ctx->getMachOSection("__DWARF", "__apple_namespac", MachO::S_ATTR_DEBUG,
 194                            SectionKind::getMetadata(), "namespac_begin");
 195   DwarfAccelTypesSection =
 196       Ctx->getMachOSection("__DWARF", "__apple_types", MachO::S_ATTR_DEBUG,
 197                            SectionKind::getMetadata(), "types_begin");
 198
 199   DwarfAbbrevSection =
 200       Ctx->getMachOSection("__DWARF", "__debug_abbrev", MachO::S_ATTR_DEBUG,
 201                            SectionKind::getMetadata(), "section_abbrev");
 202   DwarfInfoSection =
 203       Ctx->getMachOSection("__DWARF", "__debug_info", MachO::S_ATTR_DEBUG,
 204                            SectionKind::getMetadata(), "section_info");
 205   DwarfLineSection =
 206       Ctx->getMachOSection("__DWARF", "__debug_line", MachO::S_ATTR_DEBUG,
 207                            SectionKind::getMetadata(), "section_line");
 208   DwarfFrameSection =
 209       Ctx->getMachOSection("__DWARF", "__debug_frame", MachO::S_ATTR_DEBUG,
 210                            SectionKind::getMetadata());
 211   DwarfPubNamesSection =
 212       Ctx->getMachOSection("__DWARF", "__debug_pubnames", MachO::S_ATTR_DEBUG,
 213                            SectionKind::getMetadata());
 214   DwarfPubTypesSection =
 215       Ctx->getMachOSection("__DWARF", "__debug_pubtypes", MachO::S_ATTR_DEBUG,
 216                            SectionKind::getMetadata());
 217   DwarfGnuPubNamesSection =
 218       Ctx->getMachOSection("__DWARF", "__debug_gnu_pubn", MachO::S_ATTR_DEBUG,
 219                            SectionKind::getMetadata());
 220   DwarfGnuPubTypesSection =
 221       Ctx->getMachOSection("__DWARF", "__debug_gnu_pubt", MachO::S_ATTR_DEBUG,
 222                            SectionKind::getMetadata());
 223   DwarfStrSection =
 224       Ctx->getMachOSection("__DWARF", "__debug_str", MachO::S_ATTR_DEBUG,
 225                            SectionKind::getMetadata(), "info_string");
 226   DwarfLocSection =
 227       Ctx->getMachOSection("__DWARF", "__debug_loc", MachO::S_ATTR_DEBUG,
 228                            SectionKind::getMetadata(), "section_debug_loc");
 229   DwarfARangesSection =
 230       Ctx->getMachOSection("__DWARF", "__debug_aranges", MachO::S_ATTR_DEBUG,
 231                            SectionKind::getMetadata());
 232   DwarfRangesSection =
 233       Ctx->getMachOSection("__DWARF", "__debug_ranges", MachO::S_ATTR_DEBUG,
 234                            SectionKind::getMetadata(), "debug_range");
 235   DwarfDebugInlineSection =
 236       Ctx->getMachOSection("__DWARF", "__debug_inlined", MachO::S_ATTR_DEBUG,
 237                            SectionKind::getMetadata());
 238   StackMapSection = Ctx->getMachOSection("__LLVM_STACKMAPS", "__llvm_stackmaps",
 239                                          0, SectionKind::getMetadata());
 240
 241   TLSExtraDataSection = TLSTLVSection;
 242 }
 243
 244 void MCObjectFileInfo::InitELFMCObjectFileInfo(Triple T) {
 245   switch (T.getArch()) {
 246   case Triple::mips:
 247   case Triple::mipsel:
 248     FDECFIEncoding = dwarf::DW_EH_PE_sdata4;
 249     break;
 250   case Triple::mips64:
 251   case Triple::mips64el:
 252     FDECFIEncoding = dwarf::DW_EH_PE_sdata8;
 253     break;
 254   case Triple::x86_64:
 255     FDECFIEncoding = dwarf::DW_EH_PE_pcrel |
 256                      ((CMModel == CodeModel::Large) ? dwarf::DW_EH_PE_sdata8
 257                                                     : dwarf::DW_EH_PE_sdata4);
 258
 259     break;
 260   default:
 261     FDECFIEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 262     break;
 263   }
 264
 265   switch (T.getArch()) {
 266   case Triple::arm:
 267   case Triple::armeb:
 268   case Triple::thumb:
 269   case Triple::thumbeb:
 270     if (Ctx->getAsmInfo()->getExceptionHandlingType() == ExceptionHandling::ARM)
 271       break;
 272     // Fallthrough if not using EHABI
 273   case Triple::ppc:
 274   case Triple::x86:
 275     PersonalityEncoding = (RelocM == Reloc::PIC_)
 276      ? dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
 277      : dwarf::DW_EH_PE_absptr;
 278     LSDAEncoding = (RelocM == Reloc::PIC_)
 279       ? dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
 280       : dwarf::DW_EH_PE_absptr;
 281     TTypeEncoding = (RelocM == Reloc::PIC_)
 282      ? dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
 283      : dwarf::DW_EH_PE_absptr;
 284     break;
 285   case Triple::x86_64:
 286     if (RelocM == Reloc::PIC_) {
 287       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 288         ((CMModel == CodeModel::Small || CMModel == CodeModel::Medium)
 289          ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
 290       LSDAEncoding = dwarf::DW_EH_PE_pcrel |
 291         (CMModel == CodeModel::Small
 292          ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
 293       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 294         ((CMModel == CodeModel::Small || CMModel == CodeModel::Medium)
 295          ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
 296     } else {
 297       PersonalityEncoding =
 298         (CMModel == CodeModel::Small || CMModel == CodeModel::Medium)
 299         ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
 300       LSDAEncoding = (CMModel == CodeModel::Small)
 301         ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
 302       TTypeEncoding = (CMModel == CodeModel::Small)
 303         ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
 304     }
 305     break;
 306   case Triple::aarch64:
 307   case Triple::aarch64_be:
 308     // The small model guarantees static code/data size < 4GB, but not where it
 309     // will be in memory. Most of these could end up >2GB away so even a signed
 310     // pc-relative 32-bit address is insufficient, theoretically.
 311     if (RelocM == Reloc::PIC_) {
 312       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 313         dwarf::DW_EH_PE_sdata8;
 314       LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8;
 315       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 316         dwarf::DW_EH_PE_sdata8;
 317     } else {
 318       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 319       LSDAEncoding = dwarf::DW_EH_PE_absptr;
 320       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 321     }
 322     break;
 323   case Triple::mips:
 324   case Triple::mipsel:
 325   case Triple::mips64:
 326   case Triple::mips64el:
 327     // MIPS uses indirect pointer to refer personality functions and types, so
 328     // that the eh_frame section can be read-only. DW.ref.personality will be
 329     // generated for relocation.
 330     PersonalityEncoding = dwarf::DW_EH_PE_indirect;
 331     TTypeEncoding = SelectMipsTTypeEncoding();
 332     // We don't support PC-relative LSDA references in GAS so we use the default
 333     // DW_EH_PE_absptr for those.
 334     break;
 335   case Triple::ppc64:
 336   case Triple::ppc64le:
 337     PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 338       dwarf::DW_EH_PE_udata8;
 339     LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8;
 340     TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 341       dwarf::DW_EH_PE_udata8;
 342     break;
 343   case Triple::sparcel:
 344   case Triple::sparc:
 345     if (RelocM == Reloc::PIC_) {
 346       LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 347       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 348         dwarf::DW_EH_PE_sdata4;
 349       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 350         dwarf::DW_EH_PE_sdata4;
 351     } else {
 352       LSDAEncoding = dwarf::DW_EH_PE_absptr;
 353       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 354       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 355     }
 356     break;
 357   case Triple::sparcv9:
 358     LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 359     if (RelocM == Reloc::PIC_) {
 360       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 361         dwarf::DW_EH_PE_sdata4;
 362       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 363         dwarf::DW_EH_PE_sdata4;
 364     } else {
 365       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 366       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 367     }
 368     break;
 369   case Triple::systemz:
 370     // All currently-defined code models guarantee that 4-byte PC-relative
 371     // values will be in range.
 372     if (RelocM == Reloc::PIC_) {
 373       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 374         dwarf::DW_EH_PE_sdata4;
 375       LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 376       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 377         dwarf::DW_EH_PE_sdata4;
 378     } else {
 379       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 380       LSDAEncoding = dwarf::DW_EH_PE_absptr;
 381       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 382     }
 383     break;
 384   default:
 385     break;
 386   }
 387
 388   // Solaris requires different flags for .eh_frame to seemingly every other
 389   // platform.
 390   EHSectionType = ELF::SHT_PROGBITS;
 391   EHSectionFlags = ELF::SHF_ALLOC;
 392   if (T.isOSSolaris()) {
 393     if (T.getArch() == Triple::x86_64)
 394       EHSectionType = ELF::SHT_X86_64_UNWIND;
 395     else
 396       EHSectionFlags |= ELF::SHF_WRITE;
 397   }
 398
 399
 400   // ELF
 401   BSSSection = Ctx->getELFSection(".bss", ELF::SHT_NOBITS,
 402                                   ELF::SHF_WRITE | ELF::SHF_ALLOC);
 403
 404   TextSection = Ctx->getELFSection(".text", ELF::SHT_PROGBITS,
 405                                    ELF::SHF_EXECINSTR | ELF::SHF_ALLOC);
 406
 407   DataSection = Ctx->getELFSection(".data", ELF::SHT_PROGBITS,
 408                                    ELF::SHF_WRITE | ELF::SHF_ALLOC);
 409
 410   ReadOnlySection =
 411       Ctx->getELFSection(".rodata", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
 412
 413   TLSDataSection =
 414       Ctx->getELFSection(".tdata", ELF::SHT_PROGBITS,
 415                          ELF::SHF_ALLOC | ELF::SHF_TLS | ELF::SHF_WRITE);
 416
 417   TLSBSSSection = Ctx->getELFSection(
 418       ".tbss", ELF::SHT_NOBITS, ELF::SHF_ALLOC | ELF::SHF_TLS | ELF::SHF_WRITE);
 419
 420   DataRelSection = Ctx->getELFSection(".data.rel", ELF::SHT_PROGBITS,
 421                                       ELF::SHF_ALLOC | ELF::SHF_WRITE);
 422
 423   DataRelLocalSection = Ctx->getELFSection(".data.rel.local", ELF::SHT_PROGBITS,
 424                                            ELF::SHF_ALLOC | ELF::SHF_WRITE);
 425
 426   DataRelROSection = Ctx->getELFSection(".data.rel.ro", ELF::SHT_PROGBITS,
 427                                         ELF::SHF_ALLOC | ELF::SHF_WRITE);
 428
 429   DataRelROLocalSection = Ctx->getELFSection(
 430       ".data.rel.ro.local", ELF::SHT_PROGBITS, ELF::SHF_ALLOC | ELF::SHF_WRITE);
 431
 432   MergeableConst4Section =
 433       Ctx->getELFSection(".rodata.cst4", ELF::SHT_PROGBITS,
 434                          ELF::SHF_ALLOC | ELF::SHF_MERGE, 4, "");
 435
 436   MergeableConst8Section =
 437       Ctx->getELFSection(".rodata.cst8", ELF::SHT_PROGBITS,
 438                          ELF::SHF_ALLOC | ELF::SHF_MERGE, 8, "");
 439
 440   MergeableConst16Section =
 441       Ctx->getELFSection(".rodata.cst16", ELF::SHT_PROGBITS,
 442                          ELF::SHF_ALLOC | ELF::SHF_MERGE, 16, "");
 443
 444   StaticCtorSection = Ctx->getELFSection(".ctors", ELF::SHT_PROGBITS,
 445                                          ELF::SHF_ALLOC | ELF::SHF_WRITE);
 446
 447   StaticDtorSection = Ctx->getELFSection(".dtors", ELF::SHT_PROGBITS,
 448                                          ELF::SHF_ALLOC | ELF::SHF_WRITE);
 449
 450   // Exception Handling Sections.
 451
 452   // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
 453   // it contains relocatable pointers.  In PIC mode, this is probably a big
 454   // runtime hit for C++ apps.  Either the contents of the LSDA need to be
 455   // adjusted or this should be a data section.
 456   LSDASection = Ctx->getELFSection(".gcc_except_table", ELF::SHT_PROGBITS,
 457                                    ELF::SHF_ALLOC);
 458
 459   COFFDebugSymbolsSection = nullptr;
 460
 461   // Debug Info Sections.
 462   DwarfAbbrevSection = Ctx->getELFSection(".debug_abbrev", ELF::SHT_PROGBITS, 0,
 463                                           "section_abbrev");
 464   DwarfInfoSection =
 465       Ctx->getELFSection(".debug_info", ELF::SHT_PROGBITS, 0, "section_info");
 466   DwarfLineSection = Ctx->getELFSection(".debug_line", ELF::SHT_PROGBITS, 0);
 467   DwarfFrameSection = Ctx->getELFSection(".debug_frame", ELF::SHT_PROGBITS, 0);
 468   DwarfPubNamesSection =
 469       Ctx->getELFSection(".debug_pubnames", ELF::SHT_PROGBITS, 0);
 470   DwarfPubTypesSection =
 471       Ctx->getELFSection(".debug_pubtypes", ELF::SHT_PROGBITS, 0);
 472   DwarfGnuPubNamesSection =
 473       Ctx->getELFSection(".debug_gnu_pubnames", ELF::SHT_PROGBITS, 0);
 474   DwarfGnuPubTypesSection =
 475       Ctx->getELFSection(".debug_gnu_pubtypes", ELF::SHT_PROGBITS, 0);
 476   DwarfStrSection =
 477       Ctx->getELFSection(".debug_str", ELF::SHT_PROGBITS,
 478                          ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
 479   DwarfLocSection = Ctx->getELFSection(".debug_loc", ELF::SHT_PROGBITS, 0);
 480   DwarfARangesSection =
 481       Ctx->getELFSection(".debug_aranges", ELF::SHT_PROGBITS, 0);
 482   DwarfRangesSection =
 483       Ctx->getELFSection(".debug_ranges", ELF::SHT_PROGBITS, 0, "debug_range");
 484
 485   // DWARF5 Experimental Debug Info
 486
 487   // Accelerator Tables
 488   DwarfAccelNamesSection =
 489       Ctx->getELFSection(".apple_names", ELF::SHT_PROGBITS, 0, "names_begin");
 490   DwarfAccelObjCSection =
 491       Ctx->getELFSection(".apple_objc", ELF::SHT_PROGBITS, 0, "objc_begin");
 492   DwarfAccelNamespaceSection = Ctx->getELFSection(
 493       ".apple_namespaces", ELF::SHT_PROGBITS, 0, "namespac_begin");
 494   DwarfAccelTypesSection =
 495       Ctx->getELFSection(".apple_types", ELF::SHT_PROGBITS, 0, "types_begin");
 496
 497   // Fission Sections
 498   DwarfInfoDWOSection =
 499       Ctx->getELFSection(".debug_info.dwo", ELF::SHT_PROGBITS, 0);
 500   DwarfTypesDWOSection =
 501       Ctx->getELFSection(".debug_types.dwo", ELF::SHT_PROGBITS, 0);
 502   DwarfAbbrevDWOSection =
 503       Ctx->getELFSection(".debug_abbrev.dwo", ELF::SHT_PROGBITS, 0);
 504   DwarfStrDWOSection =
 505       Ctx->getELFSection(".debug_str.dwo", ELF::SHT_PROGBITS,
 506                          ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
 507   DwarfLineDWOSection =
 508       Ctx->getELFSection(".debug_line.dwo", ELF::SHT_PROGBITS, 0);
 509   DwarfLocDWOSection =
 510       Ctx->getELFSection(".debug_loc.dwo", ELF::SHT_PROGBITS, 0, "skel_loc");
 511   DwarfStrOffDWOSection =
 512       Ctx->getELFSection(".debug_str_offsets.dwo", ELF::SHT_PROGBITS, 0);
 513   DwarfAddrSection =
 514       Ctx->getELFSection(".debug_addr", ELF::SHT_PROGBITS, 0, "addr_sec");
 515
 516   StackMapSection =
 517       Ctx->getELFSection(".llvm_stackmaps", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
 518 }
 519
 520 void MCObjectFileInfo::InitCOFFMCObjectFileInfo(Triple T) {
 521   bool IsWoA = T.getArch() == Triple::arm || T.getArch() == Triple::thumb;
 522
 523   CommDirectiveSupportsAlignment = true;
 524
 525   // COFF
 526   BSSSection = Ctx->getCOFFSection(
 527       ".bss", COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
 528                   COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
 529       SectionKind::getBSS());
 530   TextSection = Ctx->getCOFFSection(
 531       ".text",
 532       (IsWoA ? COFF::IMAGE_SCN_MEM_16BIT : (COFF::SectionCharacteristics)0) |
 533           COFF::IMAGE_SCN_CNT_CODE | COFF::IMAGE_SCN_MEM_EXECUTE |
 534           COFF::IMAGE_SCN_MEM_READ,
 535       SectionKind::getText());
 536   DataSection = Ctx->getCOFFSection(
 537       ".data", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
 538                    COFF::IMAGE_SCN_MEM_WRITE,
 539       SectionKind::getDataRel());
 540   ReadOnlySection = Ctx->getCOFFSection(
 541       ".rdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
 542       SectionKind::getReadOnly());
 543
 544   if (T.isKnownWindowsMSVCEnvironment() || T.isWindowsItaniumEnvironment()) {
 545     StaticCtorSection =
 546         Ctx->getCOFFSection(".CRT$XCU", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 547                                             COFF::IMAGE_SCN_MEM_READ,
 548                             SectionKind::getReadOnly());
 549     StaticDtorSection =
 550         Ctx->getCOFFSection(".CRT$XTX", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 551                                             COFF::IMAGE_SCN_MEM_READ,
 552                             SectionKind::getReadOnly());
 553   } else {
 554     StaticCtorSection = Ctx->getCOFFSection(
 555         ".ctors", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 556                       COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
 557         SectionKind::getDataRel());
 558     StaticDtorSection = Ctx->getCOFFSection(
 559         ".dtors", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 560                       COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
 561         SectionKind::getDataRel());
 562   }
 563
 564   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
 565   // though it contains relocatable pointers.  In PIC mode, this is probably a
 566   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
 567   // adjusted or this should be a data section.
 568   assert(T.isOSWindows() && "Windows is the only supported COFF target");
 569   if (T.getArch() == Triple::x86_64) {
 570     // On Windows 64 with SEH, the LSDA is emitted into the .xdata section
 571     LSDASection = 0;
 572   } else {
 573     LSDASection = Ctx->getCOFFSection(".gcc_except_table",
 574                                       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 575                                           COFF::IMAGE_SCN_MEM_READ,
 576                                       SectionKind::getReadOnly());
 577   }
 578
 579   // Debug info.
 580   COFFDebugSymbolsSection =
 581       Ctx->getCOFFSection(".debug$S", COFF::IMAGE_SCN_MEM_DISCARDABLE |
 582                                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 583                                           COFF::IMAGE_SCN_MEM_READ,
 584                           SectionKind::getMetadata());
 585
 586   DwarfAbbrevSection = Ctx->getCOFFSection(
 587       ".debug_abbrev",
 588       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 589           COFF::IMAGE_SCN_MEM_READ,
 590       SectionKind::getMetadata(), "section_abbrev");
 591   DwarfInfoSection = Ctx->getCOFFSection(
 592       ".debug_info",
 593       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 594           COFF::IMAGE_SCN_MEM_READ,
 595       SectionKind::getMetadata(), "section_info");
 596   DwarfLineSection = Ctx->getCOFFSection(
 597       ".debug_line",
 598       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 599           COFF::IMAGE_SCN_MEM_READ,
 600       SectionKind::getMetadata(), "section_line");
 601
 602   DwarfFrameSection = Ctx->getCOFFSection(
 603       ".debug_frame",
 604       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 605           COFF::IMAGE_SCN_MEM_READ,
 606       SectionKind::getMetadata());
 607   DwarfPubNamesSection = Ctx->getCOFFSection(
 608       ".debug_pubnames",
 609       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 610           COFF::IMAGE_SCN_MEM_READ,
 611       SectionKind::getMetadata());
 612   DwarfPubTypesSection = Ctx->getCOFFSection(
 613       ".debug_pubtypes",
 614       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 615           COFF::IMAGE_SCN_MEM_READ,
 616       SectionKind::getMetadata());
 617   DwarfGnuPubNamesSection = Ctx->getCOFFSection(
 618       ".debug_gnu_pubnames",
 619       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 620           COFF::IMAGE_SCN_MEM_READ,
 621       SectionKind::getMetadata());
 622   DwarfGnuPubTypesSection = Ctx->getCOFFSection(
 623       ".debug_gnu_pubtypes",
 624       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 625           COFF::IMAGE_SCN_MEM_READ,
 626       SectionKind::getMetadata());
 627   DwarfStrSection = Ctx->getCOFFSection(
 628       ".debug_str",
 629       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 630           COFF::IMAGE_SCN_MEM_READ,
 631       SectionKind::getMetadata(), "info_string");
 632   DwarfLocSection = Ctx->getCOFFSection(
 633       ".debug_loc",
 634       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 635           COFF::IMAGE_SCN_MEM_READ,
 636       SectionKind::getMetadata(), "section_debug_loc");
 637   DwarfARangesSection = Ctx->getCOFFSection(
 638       ".debug_aranges",
 639       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 640           COFF::IMAGE_SCN_MEM_READ,
 641       SectionKind::getMetadata());
 642   DwarfRangesSection = Ctx->getCOFFSection(
 643       ".debug_ranges",
 644       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 645           COFF::IMAGE_SCN_MEM_READ,
 646       SectionKind::getMetadata(), "debug_range");
 647   DwarfInfoDWOSection = Ctx->getCOFFSection(
 648       ".debug_info.dwo",
 649       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 650           COFF::IMAGE_SCN_MEM_READ,
 651       SectionKind::getMetadata(), "section_info_dwo");
 652   DwarfTypesDWOSection = Ctx->getCOFFSection(
 653       ".debug_types.dwo",
 654       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 655           COFF::IMAGE_SCN_MEM_READ,
 656       SectionKind::getMetadata(), "section_types_dwo");
 657   DwarfAbbrevDWOSection = Ctx->getCOFFSection(
 658       ".debug_abbrev.dwo",
 659       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 660           COFF::IMAGE_SCN_MEM_READ,
 661       SectionKind::getMetadata(), "section_abbrev_dwo");
 662   DwarfStrDWOSection = Ctx->getCOFFSection(
 663       ".debug_str.dwo",
 664       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 665           COFF::IMAGE_SCN_MEM_READ,
 666       SectionKind::getMetadata(), "skel_string");
 667   DwarfLineDWOSection = Ctx->getCOFFSection(
 668       ".debug_line.dwo",
 669       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 670           COFF::IMAGE_SCN_MEM_READ,
 671       SectionKind::getMetadata());
 672   DwarfLocDWOSection = Ctx->getCOFFSection(
 673       ".debug_loc.dwo",
 674       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 675           COFF::IMAGE_SCN_MEM_READ,
 676       SectionKind::getMetadata(), "skel_loc");
 677   DwarfStrOffDWOSection = Ctx->getCOFFSection(
 678       ".debug_str_offsets.dwo",
 679       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 680           COFF::IMAGE_SCN_MEM_READ,
 681       SectionKind::getMetadata());
 682   DwarfAddrSection = Ctx->getCOFFSection(
 683       ".debug_addr",
 684       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 685           COFF::IMAGE_SCN_MEM_READ,
 686       SectionKind::getMetadata(), "addr_sec");
 687   DwarfAccelNamesSection = Ctx->getCOFFSection(
 688       ".apple_names",
 689       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 690           COFF::IMAGE_SCN_MEM_READ,
 691       SectionKind::getMetadata(), "names_begin");
 692   DwarfAccelNamespaceSection = Ctx->getCOFFSection(
 693       ".apple_namespaces",
 694       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 695           COFF::IMAGE_SCN_MEM_READ,
 696       SectionKind::getMetadata(), "namespac_begin");
 697   DwarfAccelTypesSection = Ctx->getCOFFSection(
 698       ".apple_types",
 699       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 700           COFF::IMAGE_SCN_MEM_READ,
 701       SectionKind::getMetadata(), "types_begin");
 702   DwarfAccelObjCSection = Ctx->getCOFFSection(
 703       ".apple_objc",
 704       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 705           COFF::IMAGE_SCN_MEM_READ,
 706       SectionKind::getMetadata(), "objc_begin");
 707
 708   DrectveSection = Ctx->getCOFFSection(
 709       ".drectve", COFF::IMAGE_SCN_LNK_INFO | COFF::IMAGE_SCN_LNK_REMOVE,
 710       SectionKind::getMetadata());
 711
 712   PDataSection = Ctx->getCOFFSection(
 713       ".pdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
 714       SectionKind::getDataRel());
 715
 716   XDataSection = Ctx->getCOFFSection(
 717       ".xdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
 718       SectionKind::getDataRel());
 719
 720   TLSDataSection = Ctx->getCOFFSection(
 721       ".tls$", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
 722                    COFF::IMAGE_SCN_MEM_WRITE,
 723       SectionKind::getDataRel());
 724 }
 725
 726 void MCObjectFileInfo::InitMCObjectFileInfo(StringRef T, Reloc::Model relocm,
 727                                             CodeModel::Model cm,
 728                                             MCContext &ctx) {
 729   RelocM = relocm;
 730   CMModel = cm;
 731   Ctx = &ctx;
 732
 733   // Common.
 734   CommDirectiveSupportsAlignment = true;
 735   SupportsWeakOmittedEHFrame = true;
 736   SupportsCompactUnwindWithoutEHFrame = false;
 737
 738   PersonalityEncoding = LSDAEncoding = FDECFIEncoding = TTypeEncoding =
 739       dwarf::DW_EH_PE_absptr;
 740
 741   CompactUnwindDwarfEHFrameOnly = 0;
 742
 743   EHFrameSection = nullptr;             // Created on demand.
 744   CompactUnwindSection = nullptr;       // Used only by selected targets.
 745   DwarfAccelNamesSection = nullptr;     // Used only by selected targets.
 746   DwarfAccelObjCSection = nullptr;      // Used only by selected targets.
 747   DwarfAccelNamespaceSection = nullptr; // Used only by selected targets.
 748   DwarfAccelTypesSection = nullptr;     // Used only by selected targets.
 749
 750   TT = Triple(T);
 751
 752   Triple::ArchType Arch = TT.getArch();
 753   // FIXME: Checking for Arch here to filter out bogus triples such as
 754   // cellspu-apple-darwin. Perhaps we should fix in Triple?
 755   if ((Arch == Triple::x86 || Arch == Triple::x86_64 ||
 756        Arch == Triple::arm || Arch == Triple::thumb ||
 757        Arch == Triple::aarch64 ||
 758        Arch == Triple::ppc || Arch == Triple::ppc64 ||
 759        Arch == Triple::UnknownArch) &&
 760       TT.isOSBinFormatMachO()) {
 761     Env = IsMachO;
 762     InitMachOMCObjectFileInfo(TT);
 763   } else if ((Arch == Triple::x86 || Arch == Triple::x86_64 ||
 764               Arch == Triple::arm || Arch == Triple::thumb) &&
 765              (TT.isOSWindows() && TT.getObjectFormat() == Triple::COFF)) {
 766     Env = IsCOFF;
 767     InitCOFFMCObjectFileInfo(TT);
 768   } else {
 769     Env = IsELF;
 770     InitELFMCObjectFileInfo(TT);
 771   }
 772 }
 773
 774 MCSection *MCObjectFileInfo::getDwarfTypesSection(uint64_t Hash) const {
 775   return Ctx->getELFSection(".debug_types", ELF::SHT_PROGBITS, ELF::SHF_GROUP,
 776                             0, utostr(Hash));
 777 }
 778
 779 void MCObjectFileInfo::InitEHFrameSection() {
 780   if (Env == IsMachO)
 781     EHFrameSection =
 782       Ctx->getMachOSection("__TEXT", "__eh_frame",
 783                            MachO::S_COALESCED |
 784                            MachO::S_ATTR_NO_TOC |
 785                            MachO::S_ATTR_STRIP_STATIC_SYMS |
 786                            MachO::S_ATTR_LIVE_SUPPORT,
 787                            SectionKind::getReadOnly());
 788   else if (Env == IsELF)
 789     EHFrameSection =
 790         Ctx->getELFSection(".eh_frame", EHSectionType, EHSectionFlags);
 791   else
 792     EHFrameSection =
 793       Ctx->getCOFFSection(".eh_frame",
 794                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 795                           COFF::IMAGE_SCN_MEM_READ |
 796                           COFF::IMAGE_SCN_MEM_WRITE,
 797                           SectionKind::getDataRel());
 798 }
 799
 800 unsigned MCObjectFileInfo::SelectMipsTTypeEncoding() const {
 801   // FIXME: The N64 ABI ought to use DW_EH_PE_sdata8 but we can't
 802   //        identify N64 from just a triple. We currently fix this by
 803   //        overriding this function in MipsTargetObjectFile.
 804   return dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 805          dwarf::DW_EH_PE_sdata4;
 806 }