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",
 187                          MachO::S_ATTR_DEBUG,
 188                          SectionKind::getMetadata());
 189   DwarfAccelObjCSection =
 190     Ctx->getMachOSection("__DWARF", "__apple_objc",
 191                          MachO::S_ATTR_DEBUG,
 192                          SectionKind::getMetadata());
 193   // 16 character section limit...
 194   DwarfAccelNamespaceSection =
 195     Ctx->getMachOSection("__DWARF", "__apple_namespac",
 196                          MachO::S_ATTR_DEBUG,
 197                          SectionKind::getMetadata());
 198   DwarfAccelTypesSection =
 199     Ctx->getMachOSection("__DWARF", "__apple_types",
 200                          MachO::S_ATTR_DEBUG,
 201                          SectionKind::getMetadata());
 202
 203   DwarfAbbrevSection =
 204     Ctx->getMachOSection("__DWARF", "__debug_abbrev",
 205                          MachO::S_ATTR_DEBUG,
 206                          SectionKind::getMetadata());
 207   DwarfInfoSection =
 208     Ctx->getMachOSection("__DWARF", "__debug_info",
 209                          MachO::S_ATTR_DEBUG,
 210                          SectionKind::getMetadata());
 211   DwarfLineSection =
 212     Ctx->getMachOSection("__DWARF", "__debug_line",
 213                          MachO::S_ATTR_DEBUG,
 214                          SectionKind::getMetadata());
 215   DwarfFrameSection =
 216     Ctx->getMachOSection("__DWARF", "__debug_frame",
 217                          MachO::S_ATTR_DEBUG,
 218                          SectionKind::getMetadata());
 219   DwarfPubNamesSection =
 220     Ctx->getMachOSection("__DWARF", "__debug_pubnames",
 221                          MachO::S_ATTR_DEBUG,
 222                          SectionKind::getMetadata());
 223   DwarfPubTypesSection =
 224     Ctx->getMachOSection("__DWARF", "__debug_pubtypes",
 225                          MachO::S_ATTR_DEBUG,
 226                          SectionKind::getMetadata());
 227   DwarfGnuPubNamesSection =
 228     Ctx->getMachOSection("__DWARF", "__debug_gnu_pubn",
 229                          MachO::S_ATTR_DEBUG,
 230                          SectionKind::getMetadata());
 231   DwarfGnuPubTypesSection =
 232     Ctx->getMachOSection("__DWARF", "__debug_gnu_pubt",
 233                          MachO::S_ATTR_DEBUG,
 234                          SectionKind::getMetadata());
 235   DwarfStrSection =
 236     Ctx->getMachOSection("__DWARF", "__debug_str",
 237                          MachO::S_ATTR_DEBUG,
 238                          SectionKind::getMetadata());
 239   DwarfLocSection =
 240     Ctx->getMachOSection("__DWARF", "__debug_loc",
 241                          MachO::S_ATTR_DEBUG,
 242                          SectionKind::getMetadata());
 243   DwarfARangesSection =
 244     Ctx->getMachOSection("__DWARF", "__debug_aranges",
 245                          MachO::S_ATTR_DEBUG,
 246                          SectionKind::getMetadata());
 247   DwarfRangesSection =
 248     Ctx->getMachOSection("__DWARF", "__debug_ranges",
 249                          MachO::S_ATTR_DEBUG,
 250                          SectionKind::getMetadata());
 251   DwarfMacroInfoSection =
 252     Ctx->getMachOSection("__DWARF", "__debug_macinfo",
 253                          MachO::S_ATTR_DEBUG,
 254                          SectionKind::getMetadata());
 255   DwarfDebugInlineSection =
 256     Ctx->getMachOSection("__DWARF", "__debug_inlined",
 257                          MachO::S_ATTR_DEBUG,
 258                          SectionKind::getMetadata());
 259   StackMapSection =
 260     Ctx->getMachOSection("__LLVM_STACKMAPS", "__llvm_stackmaps", 0,
 261                          SectionKind::getMetadata());
 262
 263   TLSExtraDataSection = TLSTLVSection;
 264 }
 265
 266 void MCObjectFileInfo::InitELFMCObjectFileInfo(Triple T) {
 267   switch (T.getArch()) {
 268   case Triple::mips:
 269   case Triple::mipsel:
 270     FDECFIEncoding = dwarf::DW_EH_PE_sdata4;
 271     break;
 272   case Triple::mips64:
 273   case Triple::mips64el:
 274     FDECFIEncoding = dwarf::DW_EH_PE_sdata8;
 275     break;
 276   default:
 277     FDECFIEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 278     break;
 279   }
 280
 281   switch (T.getArch()) {
 282   case Triple::arm:
 283   case Triple::armeb:
 284   case Triple::thumb:
 285   case Triple::thumbeb:
 286     if (Ctx->getAsmInfo()->getExceptionHandlingType() == ExceptionHandling::ARM)
 287       break;
 288     // Fallthrough if not using EHABI
 289   case Triple::x86:
 290     PersonalityEncoding = (RelocM == Reloc::PIC_)
 291      ? dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
 292      : dwarf::DW_EH_PE_absptr;
 293     LSDAEncoding = (RelocM == Reloc::PIC_)
 294       ? dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
 295       : dwarf::DW_EH_PE_absptr;
 296     TTypeEncoding = (RelocM == Reloc::PIC_)
 297      ? dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
 298      : dwarf::DW_EH_PE_absptr;
 299     break;
 300   case Triple::x86_64:
 301     if (RelocM == Reloc::PIC_) {
 302       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 303         ((CMModel == CodeModel::Small || CMModel == CodeModel::Medium)
 304          ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
 305       LSDAEncoding = dwarf::DW_EH_PE_pcrel |
 306         (CMModel == CodeModel::Small
 307          ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
 308       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 309         ((CMModel == CodeModel::Small || CMModel == CodeModel::Medium)
 310          ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
 311     } else {
 312       PersonalityEncoding =
 313         (CMModel == CodeModel::Small || CMModel == CodeModel::Medium)
 314         ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
 315       LSDAEncoding = (CMModel == CodeModel::Small)
 316         ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
 317       TTypeEncoding = (CMModel == CodeModel::Small)
 318         ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
 319     }
 320     break;
 321   case Triple::aarch64:
 322   case Triple::aarch64_be:
 323     // The small model guarantees static code/data size < 4GB, but not where it
 324     // will be in memory. Most of these could end up >2GB away so even a signed
 325     // pc-relative 32-bit address is insufficient, theoretically.
 326     if (RelocM == Reloc::PIC_) {
 327       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 328         dwarf::DW_EH_PE_sdata8;
 329       LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8;
 330       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 331         dwarf::DW_EH_PE_sdata8;
 332     } else {
 333       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 334       LSDAEncoding = dwarf::DW_EH_PE_absptr;
 335       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 336     }
 337     break;
 338   case Triple::mips:
 339   case Triple::mipsel:
 340     // MIPS uses indirect pointer to refer personality functions, so that the
 341     // eh_frame section can be read-only.  DW.ref.personality will be generated
 342     // for relocation.
 343     PersonalityEncoding = dwarf::DW_EH_PE_indirect;
 344     break;
 345   case Triple::ppc64:
 346   case Triple::ppc64le:
 347     PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 348       dwarf::DW_EH_PE_udata8;
 349     LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8;
 350     TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 351       dwarf::DW_EH_PE_udata8;
 352     break;
 353   case Triple::sparc:
 354     if (RelocM == Reloc::PIC_) {
 355       LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 356       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 357         dwarf::DW_EH_PE_sdata4;
 358       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 359         dwarf::DW_EH_PE_sdata4;
 360     } else {
 361       LSDAEncoding = dwarf::DW_EH_PE_absptr;
 362       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 363       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 364     }
 365     break;
 366   case Triple::sparcv9:
 367     LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 368     if (RelocM == Reloc::PIC_) {
 369       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 370         dwarf::DW_EH_PE_sdata4;
 371       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 372         dwarf::DW_EH_PE_sdata4;
 373     } else {
 374       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 375       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 376     }
 377     break;
 378   case Triple::systemz:
 379     // All currently-defined code models guarantee that 4-byte PC-relative
 380     // values will be in range.
 381     if (RelocM == Reloc::PIC_) {
 382       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 383         dwarf::DW_EH_PE_sdata4;
 384       LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 385       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 386         dwarf::DW_EH_PE_sdata4;
 387     } else {
 388       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 389       LSDAEncoding = dwarf::DW_EH_PE_absptr;
 390       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 391     }
 392     break;
 393   default:
 394     break;
 395   }
 396
 397   // Solaris requires different flags for .eh_frame to seemingly every other
 398   // platform.
 399   EHSectionType = ELF::SHT_PROGBITS;
 400   EHSectionFlags = ELF::SHF_ALLOC;
 401   if (T.getOS() == Triple::Solaris) {
 402     if (T.getArch() == Triple::x86_64)
 403       EHSectionType = ELF::SHT_X86_64_UNWIND;
 404     else
 405       EHSectionFlags |= ELF::SHF_WRITE;
 406   }
 407
 408
 409   // ELF
 410   BSSSection =
 411     Ctx->getELFSection(".bss", ELF::SHT_NOBITS,
 412                        ELF::SHF_WRITE | ELF::SHF_ALLOC,
 413                        SectionKind::getBSS());
 414
 415   TextSection =
 416     Ctx->getELFSection(".text", ELF::SHT_PROGBITS,
 417                        ELF::SHF_EXECINSTR |
 418                        ELF::SHF_ALLOC,
 419                        SectionKind::getText());
 420
 421   DataSection =
 422     Ctx->getELFSection(".data", ELF::SHT_PROGBITS,
 423                        ELF::SHF_WRITE |ELF::SHF_ALLOC,
 424                        SectionKind::getDataRel());
 425
 426   ReadOnlySection =
 427     Ctx->getELFSection(".rodata", ELF::SHT_PROGBITS,
 428                        ELF::SHF_ALLOC,
 429                        SectionKind::getReadOnly());
 430
 431   TLSDataSection =
 432     Ctx->getELFSection(".tdata", ELF::SHT_PROGBITS,
 433                        ELF::SHF_ALLOC | ELF::SHF_TLS |
 434                        ELF::SHF_WRITE,
 435                        SectionKind::getThreadData());
 436
 437   TLSBSSSection =
 438     Ctx->getELFSection(".tbss", ELF::SHT_NOBITS,
 439                        ELF::SHF_ALLOC | ELF::SHF_TLS |
 440                        ELF::SHF_WRITE,
 441                        SectionKind::getThreadBSS());
 442
 443   DataRelSection =
 444     Ctx->getELFSection(".data.rel", ELF::SHT_PROGBITS,
 445                        ELF::SHF_ALLOC |ELF::SHF_WRITE,
 446                        SectionKind::getDataRel());
 447
 448   DataRelLocalSection =
 449     Ctx->getELFSection(".data.rel.local", ELF::SHT_PROGBITS,
 450                        ELF::SHF_ALLOC |ELF::SHF_WRITE,
 451                        SectionKind::getDataRelLocal());
 452
 453   DataRelROSection =
 454     Ctx->getELFSection(".data.rel.ro", ELF::SHT_PROGBITS,
 455                        ELF::SHF_ALLOC |ELF::SHF_WRITE,
 456                        SectionKind::getReadOnlyWithRel());
 457
 458   DataRelROLocalSection =
 459     Ctx->getELFSection(".data.rel.ro.local", ELF::SHT_PROGBITS,
 460                        ELF::SHF_ALLOC |ELF::SHF_WRITE,
 461                        SectionKind::getReadOnlyWithRelLocal());
 462
 463   MergeableConst4Section =
 464     Ctx->getELFSection(".rodata.cst4", ELF::SHT_PROGBITS,
 465                        ELF::SHF_ALLOC |ELF::SHF_MERGE,
 466                        SectionKind::getMergeableConst4());
 467
 468   MergeableConst8Section =
 469     Ctx->getELFSection(".rodata.cst8", ELF::SHT_PROGBITS,
 470                        ELF::SHF_ALLOC |ELF::SHF_MERGE,
 471                        SectionKind::getMergeableConst8());
 472
 473   MergeableConst16Section =
 474     Ctx->getELFSection(".rodata.cst16", ELF::SHT_PROGBITS,
 475                        ELF::SHF_ALLOC |ELF::SHF_MERGE,
 476                        SectionKind::getMergeableConst16());
 477
 478   StaticCtorSection =
 479     Ctx->getELFSection(".ctors", ELF::SHT_PROGBITS,
 480                        ELF::SHF_ALLOC |ELF::SHF_WRITE,
 481                        SectionKind::getDataRel());
 482
 483   StaticDtorSection =
 484     Ctx->getELFSection(".dtors", ELF::SHT_PROGBITS,
 485                        ELF::SHF_ALLOC |ELF::SHF_WRITE,
 486                        SectionKind::getDataRel());
 487
 488   // Exception Handling Sections.
 489
 490   // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
 491   // it contains relocatable pointers.  In PIC mode, this is probably a big
 492   // runtime hit for C++ apps.  Either the contents of the LSDA need to be
 493   // adjusted or this should be a data section.
 494   LSDASection =
 495     Ctx->getELFSection(".gcc_except_table", ELF::SHT_PROGBITS,
 496                        ELF::SHF_ALLOC,
 497                        SectionKind::getReadOnly());
 498
 499   COFFDebugSymbolsSection = nullptr;
 500
 501   // Debug Info Sections.
 502   DwarfAbbrevSection =
 503     Ctx->getELFSection(".debug_abbrev", ELF::SHT_PROGBITS, 0,
 504                        SectionKind::getMetadata());
 505   DwarfInfoSection =
 506     Ctx->getELFSection(".debug_info", ELF::SHT_PROGBITS, 0,
 507                        SectionKind::getMetadata());
 508   DwarfLineSection =
 509     Ctx->getELFSection(".debug_line", ELF::SHT_PROGBITS, 0,
 510                        SectionKind::getMetadata());
 511   DwarfFrameSection =
 512     Ctx->getELFSection(".debug_frame", ELF::SHT_PROGBITS, 0,
 513                        SectionKind::getMetadata());
 514   DwarfPubNamesSection =
 515     Ctx->getELFSection(".debug_pubnames", ELF::SHT_PROGBITS, 0,
 516                        SectionKind::getMetadata());
 517   DwarfPubTypesSection =
 518     Ctx->getELFSection(".debug_pubtypes", ELF::SHT_PROGBITS, 0,
 519                        SectionKind::getMetadata());
 520   DwarfGnuPubNamesSection =
 521     Ctx->getELFSection(".debug_gnu_pubnames", ELF::SHT_PROGBITS, 0,
 522                        SectionKind::getMetadata());
 523   DwarfGnuPubTypesSection =
 524     Ctx->getELFSection(".debug_gnu_pubtypes", ELF::SHT_PROGBITS, 0,
 525                        SectionKind::getMetadata());
 526   DwarfStrSection =
 527     Ctx->getELFSection(".debug_str", ELF::SHT_PROGBITS,
 528                        ELF::SHF_MERGE | ELF::SHF_STRINGS,
 529                        SectionKind::getMergeable1ByteCString());
 530   DwarfLocSection =
 531     Ctx->getELFSection(".debug_loc", ELF::SHT_PROGBITS, 0,
 532                        SectionKind::getMetadata());
 533   DwarfARangesSection =
 534     Ctx->getELFSection(".debug_aranges", ELF::SHT_PROGBITS, 0,
 535                        SectionKind::getMetadata());
 536   DwarfRangesSection =
 537     Ctx->getELFSection(".debug_ranges", ELF::SHT_PROGBITS, 0,
 538                        SectionKind::getMetadata());
 539   DwarfMacroInfoSection =
 540     Ctx->getELFSection(".debug_macinfo", ELF::SHT_PROGBITS, 0,
 541                        SectionKind::getMetadata());
 542
 543   // DWARF5 Experimental Debug Info
 544
 545   // Accelerator Tables
 546   DwarfAccelNamesSection =
 547     Ctx->getELFSection(".apple_names", ELF::SHT_PROGBITS, 0,
 548                        SectionKind::getMetadata());
 549   DwarfAccelObjCSection =
 550     Ctx->getELFSection(".apple_objc", ELF::SHT_PROGBITS, 0,
 551                        SectionKind::getMetadata());
 552   DwarfAccelNamespaceSection =
 553     Ctx->getELFSection(".apple_namespaces", ELF::SHT_PROGBITS, 0,
 554                        SectionKind::getMetadata());
 555   DwarfAccelTypesSection =
 556     Ctx->getELFSection(".apple_types", ELF::SHT_PROGBITS, 0,
 557                        SectionKind::getMetadata());
 558
 559   // Fission Sections
 560   DwarfInfoDWOSection =
 561     Ctx->getELFSection(".debug_info.dwo", ELF::SHT_PROGBITS, 0,
 562                        SectionKind::getMetadata());
 563   DwarfAbbrevDWOSection =
 564     Ctx->getELFSection(".debug_abbrev.dwo", ELF::SHT_PROGBITS, 0,
 565                        SectionKind::getMetadata());
 566   DwarfStrDWOSection =
 567     Ctx->getELFSection(".debug_str.dwo", ELF::SHT_PROGBITS,
 568                        ELF::SHF_MERGE | ELF::SHF_STRINGS,
 569                        SectionKind::getMergeable1ByteCString());
 570   DwarfLineDWOSection =
 571     Ctx->getELFSection(".debug_line.dwo", ELF::SHT_PROGBITS, 0,
 572                        SectionKind::getMetadata());
 573   DwarfLocDWOSection =
 574     Ctx->getELFSection(".debug_loc.dwo", ELF::SHT_PROGBITS, 0,
 575                        SectionKind::getMetadata());
 576   DwarfStrOffDWOSection =
 577     Ctx->getELFSection(".debug_str_offsets.dwo", ELF::SHT_PROGBITS, 0,
 578                        SectionKind::getMetadata());
 579   DwarfAddrSection =
 580     Ctx->getELFSection(".debug_addr", ELF::SHT_PROGBITS, 0,
 581                        SectionKind::getMetadata());
 582 }
 583
 584
 585 void MCObjectFileInfo::InitCOFFMCObjectFileInfo(Triple T) {
 586   bool IsWoA = T.getArch() == Triple::arm || T.getArch() == Triple::thumb;
 587
 588   // The object file format cannot represent common symbols with explicit
 589   // alignments.
 590   CommDirectiveSupportsAlignment = false;
 591
 592   // COFF
 593   BSSSection =
 594     Ctx->getCOFFSection(".bss",
 595                         COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
 596                         COFF::IMAGE_SCN_MEM_READ |
 597                         COFF::IMAGE_SCN_MEM_WRITE,
 598                         SectionKind::getBSS());
 599   TextSection =
 600     Ctx->getCOFFSection(".text",
 601                         (IsWoA ? COFF::IMAGE_SCN_MEM_16BIT
 602                                : (COFF::SectionCharacteristics)0) |
 603                         COFF::IMAGE_SCN_CNT_CODE |
 604                         COFF::IMAGE_SCN_MEM_EXECUTE |
 605                         COFF::IMAGE_SCN_MEM_READ,
 606                         SectionKind::getText());
 607   DataSection =
 608     Ctx->getCOFFSection(".data",
 609                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 610                         COFF::IMAGE_SCN_MEM_READ |
 611                         COFF::IMAGE_SCN_MEM_WRITE,
 612                         SectionKind::getDataRel());
 613   ReadOnlySection =
 614     Ctx->getCOFFSection(".rdata",
 615                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 616                         COFF::IMAGE_SCN_MEM_READ,
 617                         SectionKind::getReadOnly());
 618
 619   if (T.isKnownWindowsMSVCEnvironment() || T.isWindowsItaniumEnvironment()) {
 620     StaticCtorSection =
 621       Ctx->getCOFFSection(".CRT$XCU",
 622                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 623                           COFF::IMAGE_SCN_MEM_READ,
 624                           SectionKind::getReadOnly());
 625     StaticDtorSection =
 626       Ctx->getCOFFSection(".CRT$XTX",
 627                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 628                           COFF::IMAGE_SCN_MEM_READ,
 629                           SectionKind::getReadOnly());
 630   } else {
 631     StaticCtorSection =
 632       Ctx->getCOFFSection(".ctors",
 633                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 634                           COFF::IMAGE_SCN_MEM_READ |
 635                           COFF::IMAGE_SCN_MEM_WRITE,
 636                           SectionKind::getDataRel());
 637     StaticDtorSection =
 638       Ctx->getCOFFSection(".dtors",
 639                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 640                           COFF::IMAGE_SCN_MEM_READ |
 641                           COFF::IMAGE_SCN_MEM_WRITE,
 642                           SectionKind::getDataRel());
 643   }
 644
 645   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
 646   // though it contains relocatable pointers.  In PIC mode, this is probably a
 647   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
 648   // adjusted or this should be a data section.
 649   assert(T.isOSWindows() && "Windows is the only supported COFF target");
 650   if (T.getArch() == Triple::x86_64) {
 651     // On Windows 64 with SEH, the LSDA is emitted into the .xdata section
 652     LSDASection = 0;
 653   } else {
 654     LSDASection = Ctx->getCOFFSection(".gcc_except_table",
 655                                       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 656                                           COFF::IMAGE_SCN_MEM_READ,
 657                                       SectionKind::getReadOnly());
 658   }
 659
 660   // Debug info.
 661   COFFDebugSymbolsSection =
 662     Ctx->getCOFFSection(".debug$S",
 663                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 664                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 665                         COFF::IMAGE_SCN_MEM_READ,
 666                         SectionKind::getMetadata());
 667
 668   DwarfAbbrevSection =
 669     Ctx->getCOFFSection(".debug_abbrev",
 670                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 671                         COFF::IMAGE_SCN_MEM_READ,
 672                         SectionKind::getMetadata());
 673   DwarfInfoSection =
 674     Ctx->getCOFFSection(".debug_info",
 675                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 676                         COFF::IMAGE_SCN_MEM_READ,
 677                         SectionKind::getMetadata());
 678   DwarfLineSection =
 679     Ctx->getCOFFSection(".debug_line",
 680                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 681                         COFF::IMAGE_SCN_MEM_READ,
 682                         SectionKind::getMetadata());
 683   DwarfFrameSection =
 684     Ctx->getCOFFSection(".debug_frame",
 685                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 686                         COFF::IMAGE_SCN_MEM_READ,
 687                         SectionKind::getMetadata());
 688   DwarfPubNamesSection =
 689     Ctx->getCOFFSection(".debug_pubnames",
 690                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 691                         COFF::IMAGE_SCN_MEM_READ,
 692                         SectionKind::getMetadata());
 693   DwarfPubTypesSection =
 694     Ctx->getCOFFSection(".debug_pubtypes",
 695                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 696                         COFF::IMAGE_SCN_MEM_READ,
 697                         SectionKind::getMetadata());
 698   DwarfGnuPubNamesSection =
 699     Ctx->getCOFFSection(".debug_gnu_pubnames",
 700                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 701                         COFF::IMAGE_SCN_MEM_READ,
 702                         SectionKind::getMetadata());
 703   DwarfGnuPubTypesSection =
 704     Ctx->getCOFFSection(".debug_gnu_pubtypes",
 705                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 706                         COFF::IMAGE_SCN_MEM_READ,
 707                         SectionKind::getMetadata());
 708   DwarfStrSection =
 709     Ctx->getCOFFSection(".debug_str",
 710                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 711                         COFF::IMAGE_SCN_MEM_READ,
 712                         SectionKind::getMetadata());
 713   DwarfLocSection =
 714     Ctx->getCOFFSection(".debug_loc",
 715                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 716                         COFF::IMAGE_SCN_MEM_READ,
 717                         SectionKind::getMetadata());
 718   DwarfARangesSection =
 719     Ctx->getCOFFSection(".debug_aranges",
 720                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 721                         COFF::IMAGE_SCN_MEM_READ,
 722                         SectionKind::getMetadata());
 723   DwarfRangesSection =
 724     Ctx->getCOFFSection(".debug_ranges",
 725                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 726                         COFF::IMAGE_SCN_MEM_READ,
 727                         SectionKind::getMetadata());
 728   DwarfMacroInfoSection =
 729     Ctx->getCOFFSection(".debug_macinfo",
 730                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 731                         COFF::IMAGE_SCN_MEM_READ,
 732                         SectionKind::getMetadata());
 733   DwarfInfoDWOSection =
 734       Ctx->getCOFFSection(".debug_info.dwo",
 735                           COFF::IMAGE_SCN_MEM_DISCARDABLE |
 736                           COFF::IMAGE_SCN_MEM_READ,
 737                           SectionKind::getMetadata());
 738   DwarfAbbrevDWOSection =
 739       Ctx->getCOFFSection(".debug_abbrev.dwo",
 740                           COFF::IMAGE_SCN_MEM_DISCARDABLE |
 741                           COFF::IMAGE_SCN_MEM_READ,
 742                           SectionKind::getMetadata());
 743   DwarfStrDWOSection =
 744       Ctx->getCOFFSection(".debug_str.dwo",
 745                           COFF::IMAGE_SCN_MEM_DISCARDABLE |
 746                           COFF::IMAGE_SCN_MEM_READ,
 747                           SectionKind::getMetadata());
 748   DwarfLineDWOSection =
 749       Ctx->getCOFFSection(".debug_line.dwo",
 750                           COFF::IMAGE_SCN_MEM_DISCARDABLE |
 751                           COFF::IMAGE_SCN_MEM_READ,
 752                           SectionKind::getMetadata());
 753   DwarfLocDWOSection =
 754       Ctx->getCOFFSection(".debug_loc.dwo",
 755                           COFF::IMAGE_SCN_MEM_DISCARDABLE |
 756                           COFF::IMAGE_SCN_MEM_READ,
 757                           SectionKind::getMetadata());
 758   DwarfStrOffDWOSection =
 759       Ctx->getCOFFSection(".debug_str_offsets.dwo",
 760                           COFF::IMAGE_SCN_MEM_DISCARDABLE |
 761                           COFF::IMAGE_SCN_MEM_READ,
 762                           SectionKind::getMetadata());
 763
 764   DwarfAddrSection =
 765     Ctx->getCOFFSection(".debug_addr",
 766                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 767                         COFF::IMAGE_SCN_MEM_READ,
 768                         SectionKind::getMetadata());
 769
 770   DrectveSection =
 771     Ctx->getCOFFSection(".drectve",
 772                         COFF::IMAGE_SCN_LNK_INFO |
 773                         COFF::IMAGE_SCN_LNK_REMOVE,
 774                         SectionKind::getMetadata());
 775
 776   PDataSection =
 777     Ctx->getCOFFSection(".pdata",
 778                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 779                         COFF::IMAGE_SCN_MEM_READ,
 780                         SectionKind::getDataRel());
 781
 782   XDataSection =
 783     Ctx->getCOFFSection(".xdata",
 784                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 785                         COFF::IMAGE_SCN_MEM_READ,
 786                         SectionKind::getDataRel());
 787
 788   TLSDataSection =
 789     Ctx->getCOFFSection(".tls$",
 790                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 791                         COFF::IMAGE_SCN_MEM_READ |
 792                         COFF::IMAGE_SCN_MEM_WRITE,
 793                         SectionKind::getDataRel());
 794 }
 795
 796 void MCObjectFileInfo::InitMCObjectFileInfo(StringRef T, Reloc::Model relocm,
 797                                             CodeModel::Model cm,
 798                                             MCContext &ctx) {
 799   RelocM = relocm;
 800   CMModel = cm;
 801   Ctx = &ctx;
 802
 803   // Common.
 804   CommDirectiveSupportsAlignment = true;
 805   SupportsWeakOmittedEHFrame = true;
 806   SupportsCompactUnwindWithoutEHFrame = false;
 807
 808   PersonalityEncoding = LSDAEncoding = FDECFIEncoding = TTypeEncoding =
 809       dwarf::DW_EH_PE_absptr;
 810
 811   CompactUnwindDwarfEHFrameOnly = 0;
 812
 813   EHFrameSection = nullptr;             // Created on demand.
 814   CompactUnwindSection = nullptr;       // Used only by selected targets.
 815   DwarfAccelNamesSection = nullptr;     // Used only by selected targets.
 816   DwarfAccelObjCSection = nullptr;      // Used only by selected targets.
 817   DwarfAccelNamespaceSection = nullptr; // Used only by selected targets.
 818   DwarfAccelTypesSection = nullptr;     // Used only by selected targets.
 819
 820   TT = Triple(T);
 821
 822   Triple::ArchType Arch = TT.getArch();
 823   // FIXME: Checking for Arch here to filter out bogus triples such as
 824   // cellspu-apple-darwin. Perhaps we should fix in Triple?
 825   if ((Arch == Triple::x86 || Arch == Triple::x86_64 ||
 826        Arch == Triple::arm || Arch == Triple::thumb ||
 827        Arch == Triple::aarch64 ||
 828        Arch == Triple::ppc || Arch == Triple::ppc64 ||
 829        Arch == Triple::UnknownArch) &&
 830       (TT.isOSDarwin() || TT.isOSBinFormatMachO())) {
 831     Env = IsMachO;
 832     InitMachOMCObjectFileInfo(TT);
 833   } else if ((Arch == Triple::x86 || Arch == Triple::x86_64 ||
 834               Arch == Triple::arm || Arch == Triple::thumb) &&
 835              (TT.isOSWindows() && TT.getObjectFormat() == Triple::COFF)) {
 836     Env = IsCOFF;
 837     InitCOFFMCObjectFileInfo(TT);
 838   } else {
 839     Env = IsELF;
 840     InitELFMCObjectFileInfo(TT);
 841   }
 842 }
 843
 844 const MCSection *MCObjectFileInfo::getDwarfTypesSection(uint64_t Hash) const {
 845   return Ctx->getELFSection(".debug_types", ELF::SHT_PROGBITS, ELF::SHF_GROUP,
 846                             SectionKind::getMetadata(), 0, utostr(Hash));
 847 }
 848
 849 const MCSection *
 850 MCObjectFileInfo::getDwarfTypesDWOSection(uint64_t Hash) const {
 851   return Ctx->getELFSection(".debug_types.dwo", ELF::SHT_PROGBITS,
 852                             ELF::SHF_GROUP, SectionKind::getMetadata(), 0,
 853                             utostr(Hash));
 854 }
 855
 856 void MCObjectFileInfo::InitEHFrameSection() {
 857   if (Env == IsMachO)
 858     EHFrameSection =
 859       Ctx->getMachOSection("__TEXT", "__eh_frame",
 860                            MachO::S_COALESCED |
 861                            MachO::S_ATTR_NO_TOC |
 862                            MachO::S_ATTR_STRIP_STATIC_SYMS |
 863                            MachO::S_ATTR_LIVE_SUPPORT,
 864                            SectionKind::getReadOnly());
 865   else if (Env == IsELF)
 866     EHFrameSection =
 867       Ctx->getELFSection(".eh_frame", EHSectionType,
 868                          EHSectionFlags,
 869                          SectionKind::getDataRel());
 870   else
 871     EHFrameSection =
 872       Ctx->getCOFFSection(".eh_frame",
 873                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 874                           COFF::IMAGE_SCN_MEM_READ |
 875                           COFF::IMAGE_SCN_MEM_WRITE,
 876                           SectionKind::getDataRel());
 877 }