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   FaultMapSection = Ctx->getMachOSection("__LLVM_FAULTMAPS", "__llvm_faultmaps",
 242                                          0, SectionKind::getMetadata());
 243
 244   TLSExtraDataSection = TLSTLVSection;
 245 }
 246
 247 void MCObjectFileInfo::initELFMCObjectFileInfo(Triple T) {
 248   switch (T.getArch()) {
 249   case Triple::mips:
 250   case Triple::mipsel:
 251     FDECFIEncoding = dwarf::DW_EH_PE_sdata4;
 252     break;
 253   case Triple::mips64:
 254   case Triple::mips64el:
 255     FDECFIEncoding = dwarf::DW_EH_PE_sdata8;
 256     break;
 257   case Triple::x86_64:
 258     FDECFIEncoding = dwarf::DW_EH_PE_pcrel |
 259                      ((CMModel == CodeModel::Large) ? dwarf::DW_EH_PE_sdata8
 260                                                     : dwarf::DW_EH_PE_sdata4);
 261
 262     break;
 263   default:
 264     FDECFIEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 265     break;
 266   }
 267
 268   switch (T.getArch()) {
 269   case Triple::arm:
 270   case Triple::armeb:
 271   case Triple::thumb:
 272   case Triple::thumbeb:
 273     if (Ctx->getAsmInfo()->getExceptionHandlingType() == ExceptionHandling::ARM)
 274       break;
 275     // Fallthrough if not using EHABI
 276   case Triple::ppc:
 277   case Triple::x86:
 278     PersonalityEncoding = (RelocM == Reloc::PIC_)
 279      ? dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
 280      : dwarf::DW_EH_PE_absptr;
 281     LSDAEncoding = (RelocM == Reloc::PIC_)
 282       ? dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
 283       : dwarf::DW_EH_PE_absptr;
 284     TTypeEncoding = (RelocM == Reloc::PIC_)
 285      ? dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
 286      : dwarf::DW_EH_PE_absptr;
 287     break;
 288   case Triple::x86_64:
 289     if (RelocM == Reloc::PIC_) {
 290       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 291         ((CMModel == CodeModel::Small || CMModel == CodeModel::Medium)
 292          ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
 293       LSDAEncoding = dwarf::DW_EH_PE_pcrel |
 294         (CMModel == CodeModel::Small
 295          ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
 296       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 297         ((CMModel == CodeModel::Small || CMModel == CodeModel::Medium)
 298          ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
 299     } else {
 300       PersonalityEncoding =
 301         (CMModel == CodeModel::Small || CMModel == CodeModel::Medium)
 302         ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
 303       LSDAEncoding = (CMModel == CodeModel::Small)
 304         ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
 305       TTypeEncoding = (CMModel == CodeModel::Small)
 306         ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
 307     }
 308     break;
 309   case Triple::aarch64:
 310   case Triple::aarch64_be:
 311     // The small model guarantees static code/data size < 4GB, but not where it
 312     // will be in memory. Most of these could end up >2GB away so even a signed
 313     // pc-relative 32-bit address is insufficient, theoretically.
 314     if (RelocM == Reloc::PIC_) {
 315       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 316         dwarf::DW_EH_PE_sdata8;
 317       LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8;
 318       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 319         dwarf::DW_EH_PE_sdata8;
 320     } else {
 321       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 322       LSDAEncoding = dwarf::DW_EH_PE_absptr;
 323       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 324     }
 325     break;
 326   case Triple::mips:
 327   case Triple::mipsel:
 328   case Triple::mips64:
 329   case Triple::mips64el:
 330     // MIPS uses indirect pointer to refer personality functions and types, so
 331     // that the eh_frame section can be read-only. DW.ref.personality will be
 332     // generated for relocation.
 333     PersonalityEncoding = dwarf::DW_EH_PE_indirect;
 334     // FIXME: The N64 ABI probably ought to use DW_EH_PE_sdata8 but we can't
 335     //        identify N64 from just a triple.
 336     TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 337                     dwarf::DW_EH_PE_sdata4;
 338     // We don't support PC-relative LSDA references in GAS so we use the default
 339     // DW_EH_PE_absptr for those.
 340     break;
 341   case Triple::ppc64:
 342   case Triple::ppc64le:
 343     PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 344       dwarf::DW_EH_PE_udata8;
 345     LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8;
 346     TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 347       dwarf::DW_EH_PE_udata8;
 348     break;
 349   case Triple::sparcel:
 350   case Triple::sparc:
 351     if (RelocM == Reloc::PIC_) {
 352       LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 353       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 354         dwarf::DW_EH_PE_sdata4;
 355       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 356         dwarf::DW_EH_PE_sdata4;
 357     } else {
 358       LSDAEncoding = dwarf::DW_EH_PE_absptr;
 359       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 360       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 361     }
 362     break;
 363   case Triple::sparcv9:
 364     LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 365     if (RelocM == Reloc::PIC_) {
 366       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 367         dwarf::DW_EH_PE_sdata4;
 368       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 369         dwarf::DW_EH_PE_sdata4;
 370     } else {
 371       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 372       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 373     }
 374     break;
 375   case Triple::systemz:
 376     // All currently-defined code models guarantee that 4-byte PC-relative
 377     // values will be in range.
 378     if (RelocM == Reloc::PIC_) {
 379       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 380         dwarf::DW_EH_PE_sdata4;
 381       LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 382       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 383         dwarf::DW_EH_PE_sdata4;
 384     } else {
 385       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 386       LSDAEncoding = dwarf::DW_EH_PE_absptr;
 387       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 388     }
 389     break;
 390   default:
 391     break;
 392   }
 393
 394   // Solaris requires different flags for .eh_frame to seemingly every other
 395   // platform.
 396   EHSectionType = ELF::SHT_PROGBITS;
 397   EHSectionFlags = ELF::SHF_ALLOC;
 398   if (T.isOSSolaris()) {
 399     if (T.getArch() == Triple::x86_64)
 400       EHSectionType = ELF::SHT_X86_64_UNWIND;
 401     else
 402       EHSectionFlags |= ELF::SHF_WRITE;
 403   }
 404
 405
 406   // ELF
 407   BSSSection = Ctx->getELFSection(".bss", ELF::SHT_NOBITS,
 408                                   ELF::SHF_WRITE | ELF::SHF_ALLOC);
 409
 410   TextSection = Ctx->getELFSection(".text", ELF::SHT_PROGBITS,
 411                                    ELF::SHF_EXECINSTR | ELF::SHF_ALLOC);
 412
 413   DataSection = Ctx->getELFSection(".data", ELF::SHT_PROGBITS,
 414                                    ELF::SHF_WRITE | ELF::SHF_ALLOC);
 415
 416   ReadOnlySection =
 417       Ctx->getELFSection(".rodata", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
 418
 419   TLSDataSection =
 420       Ctx->getELFSection(".tdata", ELF::SHT_PROGBITS,
 421                          ELF::SHF_ALLOC | ELF::SHF_TLS | ELF::SHF_WRITE);
 422
 423   TLSBSSSection = Ctx->getELFSection(
 424       ".tbss", ELF::SHT_NOBITS, ELF::SHF_ALLOC | ELF::SHF_TLS | ELF::SHF_WRITE);
 425
 426   DataRelSection = Ctx->getELFSection(".data.rel", ELF::SHT_PROGBITS,
 427                                       ELF::SHF_ALLOC | ELF::SHF_WRITE);
 428
 429   DataRelLocalSection = Ctx->getELFSection(".data.rel.local", ELF::SHT_PROGBITS,
 430                                            ELF::SHF_ALLOC | ELF::SHF_WRITE);
 431
 432   DataRelROSection = Ctx->getELFSection(".data.rel.ro", ELF::SHT_PROGBITS,
 433                                         ELF::SHF_ALLOC | ELF::SHF_WRITE);
 434
 435   DataRelROLocalSection = Ctx->getELFSection(
 436       ".data.rel.ro.local", ELF::SHT_PROGBITS, ELF::SHF_ALLOC | ELF::SHF_WRITE);
 437
 438   MergeableConst4Section =
 439       Ctx->getELFSection(".rodata.cst4", ELF::SHT_PROGBITS,
 440                          ELF::SHF_ALLOC | ELF::SHF_MERGE, 4, "");
 441
 442   MergeableConst8Section =
 443       Ctx->getELFSection(".rodata.cst8", ELF::SHT_PROGBITS,
 444                          ELF::SHF_ALLOC | ELF::SHF_MERGE, 8, "");
 445
 446   MergeableConst16Section =
 447       Ctx->getELFSection(".rodata.cst16", ELF::SHT_PROGBITS,
 448                          ELF::SHF_ALLOC | ELF::SHF_MERGE, 16, "");
 449
 450   StaticCtorSection = Ctx->getELFSection(".ctors", ELF::SHT_PROGBITS,
 451                                          ELF::SHF_ALLOC | ELF::SHF_WRITE);
 452
 453   StaticDtorSection = Ctx->getELFSection(".dtors", ELF::SHT_PROGBITS,
 454                                          ELF::SHF_ALLOC | ELF::SHF_WRITE);
 455
 456   // Exception Handling Sections.
 457
 458   // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
 459   // it contains relocatable pointers.  In PIC mode, this is probably a big
 460   // runtime hit for C++ apps.  Either the contents of the LSDA need to be
 461   // adjusted or this should be a data section.
 462   LSDASection = Ctx->getELFSection(".gcc_except_table", ELF::SHT_PROGBITS,
 463                                    ELF::SHF_ALLOC);
 464
 465   COFFDebugSymbolsSection = nullptr;
 466
 467   // Debug Info Sections.
 468   DwarfAbbrevSection = Ctx->getELFSection(".debug_abbrev", ELF::SHT_PROGBITS, 0,
 469                                           "section_abbrev");
 470   DwarfInfoSection =
 471       Ctx->getELFSection(".debug_info", ELF::SHT_PROGBITS, 0, "section_info");
 472   DwarfLineSection = Ctx->getELFSection(".debug_line", ELF::SHT_PROGBITS, 0);
 473   DwarfFrameSection = Ctx->getELFSection(".debug_frame", ELF::SHT_PROGBITS, 0);
 474   DwarfPubNamesSection =
 475       Ctx->getELFSection(".debug_pubnames", ELF::SHT_PROGBITS, 0);
 476   DwarfPubTypesSection =
 477       Ctx->getELFSection(".debug_pubtypes", ELF::SHT_PROGBITS, 0);
 478   DwarfGnuPubNamesSection =
 479       Ctx->getELFSection(".debug_gnu_pubnames", ELF::SHT_PROGBITS, 0);
 480   DwarfGnuPubTypesSection =
 481       Ctx->getELFSection(".debug_gnu_pubtypes", ELF::SHT_PROGBITS, 0);
 482   DwarfStrSection =
 483       Ctx->getELFSection(".debug_str", ELF::SHT_PROGBITS,
 484                          ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
 485   DwarfLocSection = Ctx->getELFSection(".debug_loc", ELF::SHT_PROGBITS, 0);
 486   DwarfARangesSection =
 487       Ctx->getELFSection(".debug_aranges", ELF::SHT_PROGBITS, 0);
 488   DwarfRangesSection =
 489       Ctx->getELFSection(".debug_ranges", ELF::SHT_PROGBITS, 0, "debug_range");
 490
 491   // DWARF5 Experimental Debug Info
 492
 493   // Accelerator Tables
 494   DwarfAccelNamesSection =
 495       Ctx->getELFSection(".apple_names", ELF::SHT_PROGBITS, 0, "names_begin");
 496   DwarfAccelObjCSection =
 497       Ctx->getELFSection(".apple_objc", ELF::SHT_PROGBITS, 0, "objc_begin");
 498   DwarfAccelNamespaceSection = Ctx->getELFSection(
 499       ".apple_namespaces", ELF::SHT_PROGBITS, 0, "namespac_begin");
 500   DwarfAccelTypesSection =
 501       Ctx->getELFSection(".apple_types", ELF::SHT_PROGBITS, 0, "types_begin");
 502
 503   // Fission Sections
 504   DwarfInfoDWOSection =
 505       Ctx->getELFSection(".debug_info.dwo", ELF::SHT_PROGBITS, 0);
 506   DwarfTypesDWOSection =
 507       Ctx->getELFSection(".debug_types.dwo", ELF::SHT_PROGBITS, 0);
 508   DwarfAbbrevDWOSection =
 509       Ctx->getELFSection(".debug_abbrev.dwo", ELF::SHT_PROGBITS, 0);
 510   DwarfStrDWOSection =
 511       Ctx->getELFSection(".debug_str.dwo", ELF::SHT_PROGBITS,
 512                          ELF::SHF_MERGE | ELF::SHF_STRINGS, 1, "");
 513   DwarfLineDWOSection =
 514       Ctx->getELFSection(".debug_line.dwo", ELF::SHT_PROGBITS, 0);
 515   DwarfLocDWOSection =
 516       Ctx->getELFSection(".debug_loc.dwo", ELF::SHT_PROGBITS, 0, "skel_loc");
 517   DwarfStrOffDWOSection =
 518       Ctx->getELFSection(".debug_str_offsets.dwo", ELF::SHT_PROGBITS, 0);
 519   DwarfAddrSection =
 520       Ctx->getELFSection(".debug_addr", ELF::SHT_PROGBITS, 0, "addr_sec");
 521
 522   StackMapSection =
 523       Ctx->getELFSection(".llvm_stackmaps", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
 524
 525   FaultMapSection =
 526       Ctx->getELFSection(".llvm_faultmaps", ELF::SHT_PROGBITS, ELF::SHF_ALLOC);
 527 }
 528
 529 void MCObjectFileInfo::initCOFFMCObjectFileInfo(Triple T) {
 530   bool IsWoA = T.getArch() == Triple::arm || T.getArch() == Triple::thumb;
 531
 532   CommDirectiveSupportsAlignment = true;
 533
 534   // COFF
 535   BSSSection = Ctx->getCOFFSection(
 536       ".bss", COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
 537                   COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
 538       SectionKind::getBSS());
 539   TextSection = Ctx->getCOFFSection(
 540       ".text",
 541       (IsWoA ? COFF::IMAGE_SCN_MEM_16BIT : (COFF::SectionCharacteristics)0) |
 542           COFF::IMAGE_SCN_CNT_CODE | COFF::IMAGE_SCN_MEM_EXECUTE |
 543           COFF::IMAGE_SCN_MEM_READ,
 544       SectionKind::getText());
 545   DataSection = Ctx->getCOFFSection(
 546       ".data", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
 547                    COFF::IMAGE_SCN_MEM_WRITE,
 548       SectionKind::getDataRel());
 549   ReadOnlySection = Ctx->getCOFFSection(
 550       ".rdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
 551       SectionKind::getReadOnly());
 552
 553   if (T.isKnownWindowsMSVCEnvironment() || T.isWindowsItaniumEnvironment()) {
 554     StaticCtorSection =
 555         Ctx->getCOFFSection(".CRT$XCU", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 556                                             COFF::IMAGE_SCN_MEM_READ,
 557                             SectionKind::getReadOnly());
 558     StaticDtorSection =
 559         Ctx->getCOFFSection(".CRT$XTX", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 560                                             COFF::IMAGE_SCN_MEM_READ,
 561                             SectionKind::getReadOnly());
 562   } else {
 563     StaticCtorSection = Ctx->getCOFFSection(
 564         ".ctors", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 565                       COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
 566         SectionKind::getDataRel());
 567     StaticDtorSection = Ctx->getCOFFSection(
 568         ".dtors", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 569                       COFF::IMAGE_SCN_MEM_READ | COFF::IMAGE_SCN_MEM_WRITE,
 570         SectionKind::getDataRel());
 571   }
 572
 573   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
 574   // though it contains relocatable pointers.  In PIC mode, this is probably a
 575   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
 576   // adjusted or this should be a data section.
 577   assert(T.isOSWindows() && "Windows is the only supported COFF target");
 578   if (T.getArch() == Triple::x86_64) {
 579     // On Windows 64 with SEH, the LSDA is emitted into the .xdata section
 580     LSDASection = 0;
 581   } else {
 582     LSDASection = Ctx->getCOFFSection(".gcc_except_table",
 583                                       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 584                                           COFF::IMAGE_SCN_MEM_READ,
 585                                       SectionKind::getReadOnly());
 586   }
 587
 588   // Debug info.
 589   COFFDebugSymbolsSection =
 590       Ctx->getCOFFSection(".debug$S", COFF::IMAGE_SCN_MEM_DISCARDABLE |
 591                                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 592                                           COFF::IMAGE_SCN_MEM_READ,
 593                           SectionKind::getMetadata());
 594
 595   DwarfAbbrevSection = Ctx->getCOFFSection(
 596       ".debug_abbrev",
 597       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 598           COFF::IMAGE_SCN_MEM_READ,
 599       SectionKind::getMetadata(), "section_abbrev");
 600   DwarfInfoSection = Ctx->getCOFFSection(
 601       ".debug_info",
 602       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 603           COFF::IMAGE_SCN_MEM_READ,
 604       SectionKind::getMetadata(), "section_info");
 605   DwarfLineSection = Ctx->getCOFFSection(
 606       ".debug_line",
 607       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 608           COFF::IMAGE_SCN_MEM_READ,
 609       SectionKind::getMetadata(), "section_line");
 610
 611   DwarfFrameSection = Ctx->getCOFFSection(
 612       ".debug_frame",
 613       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 614           COFF::IMAGE_SCN_MEM_READ,
 615       SectionKind::getMetadata());
 616   DwarfPubNamesSection = Ctx->getCOFFSection(
 617       ".debug_pubnames",
 618       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 619           COFF::IMAGE_SCN_MEM_READ,
 620       SectionKind::getMetadata());
 621   DwarfPubTypesSection = Ctx->getCOFFSection(
 622       ".debug_pubtypes",
 623       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 624           COFF::IMAGE_SCN_MEM_READ,
 625       SectionKind::getMetadata());
 626   DwarfGnuPubNamesSection = Ctx->getCOFFSection(
 627       ".debug_gnu_pubnames",
 628       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 629           COFF::IMAGE_SCN_MEM_READ,
 630       SectionKind::getMetadata());
 631   DwarfGnuPubTypesSection = Ctx->getCOFFSection(
 632       ".debug_gnu_pubtypes",
 633       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 634           COFF::IMAGE_SCN_MEM_READ,
 635       SectionKind::getMetadata());
 636   DwarfStrSection = Ctx->getCOFFSection(
 637       ".debug_str",
 638       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 639           COFF::IMAGE_SCN_MEM_READ,
 640       SectionKind::getMetadata(), "info_string");
 641   DwarfLocSection = Ctx->getCOFFSection(
 642       ".debug_loc",
 643       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 644           COFF::IMAGE_SCN_MEM_READ,
 645       SectionKind::getMetadata(), "section_debug_loc");
 646   DwarfARangesSection = Ctx->getCOFFSection(
 647       ".debug_aranges",
 648       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 649           COFF::IMAGE_SCN_MEM_READ,
 650       SectionKind::getMetadata());
 651   DwarfRangesSection = Ctx->getCOFFSection(
 652       ".debug_ranges",
 653       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 654           COFF::IMAGE_SCN_MEM_READ,
 655       SectionKind::getMetadata(), "debug_range");
 656   DwarfInfoDWOSection = Ctx->getCOFFSection(
 657       ".debug_info.dwo",
 658       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 659           COFF::IMAGE_SCN_MEM_READ,
 660       SectionKind::getMetadata(), "section_info_dwo");
 661   DwarfTypesDWOSection = Ctx->getCOFFSection(
 662       ".debug_types.dwo",
 663       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 664           COFF::IMAGE_SCN_MEM_READ,
 665       SectionKind::getMetadata(), "section_types_dwo");
 666   DwarfAbbrevDWOSection = Ctx->getCOFFSection(
 667       ".debug_abbrev.dwo",
 668       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 669           COFF::IMAGE_SCN_MEM_READ,
 670       SectionKind::getMetadata(), "section_abbrev_dwo");
 671   DwarfStrDWOSection = Ctx->getCOFFSection(
 672       ".debug_str.dwo",
 673       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 674           COFF::IMAGE_SCN_MEM_READ,
 675       SectionKind::getMetadata(), "skel_string");
 676   DwarfLineDWOSection = Ctx->getCOFFSection(
 677       ".debug_line.dwo",
 678       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 679           COFF::IMAGE_SCN_MEM_READ,
 680       SectionKind::getMetadata());
 681   DwarfLocDWOSection = Ctx->getCOFFSection(
 682       ".debug_loc.dwo",
 683       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 684           COFF::IMAGE_SCN_MEM_READ,
 685       SectionKind::getMetadata(), "skel_loc");
 686   DwarfStrOffDWOSection = Ctx->getCOFFSection(
 687       ".debug_str_offsets.dwo",
 688       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 689           COFF::IMAGE_SCN_MEM_READ,
 690       SectionKind::getMetadata());
 691   DwarfAddrSection = Ctx->getCOFFSection(
 692       ".debug_addr",
 693       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 694           COFF::IMAGE_SCN_MEM_READ,
 695       SectionKind::getMetadata(), "addr_sec");
 696   DwarfAccelNamesSection = Ctx->getCOFFSection(
 697       ".apple_names",
 698       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 699           COFF::IMAGE_SCN_MEM_READ,
 700       SectionKind::getMetadata(), "names_begin");
 701   DwarfAccelNamespaceSection = Ctx->getCOFFSection(
 702       ".apple_namespaces",
 703       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 704           COFF::IMAGE_SCN_MEM_READ,
 705       SectionKind::getMetadata(), "namespac_begin");
 706   DwarfAccelTypesSection = Ctx->getCOFFSection(
 707       ".apple_types",
 708       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 709           COFF::IMAGE_SCN_MEM_READ,
 710       SectionKind::getMetadata(), "types_begin");
 711   DwarfAccelObjCSection = Ctx->getCOFFSection(
 712       ".apple_objc",
 713       COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 714           COFF::IMAGE_SCN_MEM_READ,
 715       SectionKind::getMetadata(), "objc_begin");
 716
 717   DrectveSection = Ctx->getCOFFSection(
 718       ".drectve", COFF::IMAGE_SCN_LNK_INFO | COFF::IMAGE_SCN_LNK_REMOVE,
 719       SectionKind::getMetadata());
 720
 721   PDataSection = Ctx->getCOFFSection(
 722       ".pdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
 723       SectionKind::getDataRel());
 724
 725   XDataSection = Ctx->getCOFFSection(
 726       ".xdata", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
 727       SectionKind::getDataRel());
 728
 729   SXDataSection = Ctx->getCOFFSection(".sxdata", COFF::IMAGE_SCN_LNK_INFO,
 730                                       SectionKind::getMetadata());
 731
 732   TLSDataSection = Ctx->getCOFFSection(
 733       ".tls$", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
 734                    COFF::IMAGE_SCN_MEM_WRITE,
 735       SectionKind::getDataRel());
 736
 737   StackMapSection = Ctx->getCOFFSection(".llvm_stackmaps",
 738                                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 739                                             COFF::IMAGE_SCN_MEM_READ,
 740                                         SectionKind::getReadOnly());
 741 }
 742
 743 void MCObjectFileInfo::InitMCObjectFileInfo(const Triple &TheTriple,
 744                                             Reloc::Model relocm,
 745                                             CodeModel::Model cm,
 746                                             MCContext &ctx) {
 747   RelocM = relocm;
 748   CMModel = cm;
 749   Ctx = &ctx;
 750
 751   // Common.
 752   CommDirectiveSupportsAlignment = true;
 753   SupportsWeakOmittedEHFrame = true;
 754   SupportsCompactUnwindWithoutEHFrame = false;
 755
 756   PersonalityEncoding = LSDAEncoding = FDECFIEncoding = TTypeEncoding =
 757       dwarf::DW_EH_PE_absptr;
 758
 759   CompactUnwindDwarfEHFrameOnly = 0;
 760
 761   EHFrameSection = nullptr;             // Created on demand.
 762   CompactUnwindSection = nullptr;       // Used only by selected targets.
 763   DwarfAccelNamesSection = nullptr;     // Used only by selected targets.
 764   DwarfAccelObjCSection = nullptr;      // Used only by selected targets.
 765   DwarfAccelNamespaceSection = nullptr; // Used only by selected targets.
 766   DwarfAccelTypesSection = nullptr;     // Used only by selected targets.
 767
 768   TT = TheTriple;
 769
 770   Triple::ArchType Arch = TT.getArch();
 771   // FIXME: Checking for Arch here to filter out bogus triples such as
 772   // cellspu-apple-darwin. Perhaps we should fix in Triple?
 773   if ((Arch == Triple::x86 || Arch == Triple::x86_64 ||
 774        Arch == Triple::arm || Arch == Triple::thumb ||
 775        Arch == Triple::aarch64 ||
 776        Arch == Triple::ppc || Arch == Triple::ppc64 ||
 777        Arch == Triple::UnknownArch) &&
 778       TT.isOSBinFormatMachO()) {
 779     Env = IsMachO;
 780     initMachOMCObjectFileInfo(TT);
 781   } else if ((Arch == Triple::x86 || Arch == Triple::x86_64 ||
 782               Arch == Triple::arm || Arch == Triple::thumb) &&
 783              (TT.isOSWindows() && TT.getObjectFormat() == Triple::COFF)) {
 784     Env = IsCOFF;
 785     initCOFFMCObjectFileInfo(TT);
 786   } else {
 787     Env = IsELF;
 788     initELFMCObjectFileInfo(TT);
 789   }
 790 }
 791
 792 void MCObjectFileInfo::InitMCObjectFileInfo(StringRef TT, Reloc::Model RM,
 793                                             CodeModel::Model CM,
 794                                             MCContext &ctx) {
 795   InitMCObjectFileInfo(Triple(TT), RM, CM, ctx);
 796 }
 797
 798 MCSection *MCObjectFileInfo::getDwarfTypesSection(uint64_t Hash) const {
 799   return Ctx->getELFSection(".debug_types", ELF::SHT_PROGBITS, ELF::SHF_GROUP,
 800                             0, utostr(Hash));
 801 }
 802
 803 void MCObjectFileInfo::InitEHFrameSection() {
 804   if (Env == IsMachO)
 805     EHFrameSection =
 806       Ctx->getMachOSection("__TEXT", "__eh_frame",
 807                            MachO::S_COALESCED |
 808                            MachO::S_ATTR_NO_TOC |
 809                            MachO::S_ATTR_STRIP_STATIC_SYMS |
 810                            MachO::S_ATTR_LIVE_SUPPORT,
 811                            SectionKind::getReadOnly());
 812   else if (Env == IsELF)
 813     EHFrameSection =
 814         Ctx->getELFSection(".eh_frame", EHSectionType, EHSectionFlags);
 815   else
 816     EHFrameSection =
 817       Ctx->getCOFFSection(".eh_frame",
 818                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 819                           COFF::IMAGE_SCN_MEM_READ |
 820                           COFF::IMAGE_SCN_MEM_WRITE,
 821                           SectionKind::getDataRel());
 822 }