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::arm64 || 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   return false;
  35 }
  36
  37 void MCObjectFileInfo::InitMachOMCObjectFileInfo(Triple T) {
  38   // MachO
  39   IsFunctionEHFrameSymbolPrivate = false;
  40   SupportsWeakOmittedEHFrame = false;
  41
  42   if (T.isOSDarwin() &&
  43       (T.getArch() == Triple::arm64 || T.getArch() == Triple::aarch64))
  44     SupportsCompactUnwindWithoutEHFrame = true;
  45
  46   PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel
  47     | dwarf::DW_EH_PE_sdata4;
  48   LSDAEncoding = FDECFIEncoding = dwarf::DW_EH_PE_pcrel;
  49   TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
  50     dwarf::DW_EH_PE_sdata4;
  51
  52   // .comm doesn't support alignment before Leopard.
  53   if (T.isMacOSX() && T.isMacOSXVersionLT(10, 5))
  54     CommDirectiveSupportsAlignment = false;
  55
  56   TextSection // .text
  57     = Ctx->getMachOSection("__TEXT", "__text",
  58                            MachO::S_ATTR_PURE_INSTRUCTIONS,
  59                            SectionKind::getText());
  60   DataSection // .data
  61     = Ctx->getMachOSection("__DATA", "__data", 0,
  62                            SectionKind::getDataRel());
  63
  64   // BSSSection might not be expected initialized on msvc.
  65   BSSSection = nullptr;
  66
  67   TLSDataSection // .tdata
  68     = Ctx->getMachOSection("__DATA", "__thread_data",
  69                            MachO::S_THREAD_LOCAL_REGULAR,
  70                            SectionKind::getDataRel());
  71   TLSBSSSection // .tbss
  72     = Ctx->getMachOSection("__DATA", "__thread_bss",
  73                            MachO::S_THREAD_LOCAL_ZEROFILL,
  74                            SectionKind::getThreadBSS());
  75
  76   // TODO: Verify datarel below.
  77   TLSTLVSection // .tlv
  78     = Ctx->getMachOSection("__DATA", "__thread_vars",
  79                            MachO::S_THREAD_LOCAL_VARIABLES,
  80                            SectionKind::getDataRel());
  81
  82   TLSThreadInitSection
  83     = Ctx->getMachOSection("__DATA", "__thread_init",
  84                           MachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
  85                           SectionKind::getDataRel());
  86
  87   CStringSection // .cstring
  88     = Ctx->getMachOSection("__TEXT", "__cstring",
  89                            MachO::S_CSTRING_LITERALS,
  90                            SectionKind::getMergeable1ByteCString());
  91   UStringSection
  92     = Ctx->getMachOSection("__TEXT","__ustring", 0,
  93                            SectionKind::getMergeable2ByteCString());
  94   FourByteConstantSection // .literal4
  95     = Ctx->getMachOSection("__TEXT", "__literal4",
  96                            MachO::S_4BYTE_LITERALS,
  97                            SectionKind::getMergeableConst4());
  98   EightByteConstantSection // .literal8
  99     = Ctx->getMachOSection("__TEXT", "__literal8",
 100                            MachO::S_8BYTE_LITERALS,
 101                            SectionKind::getMergeableConst8());
 102
 103   SixteenByteConstantSection // .literal16
 104       = Ctx->getMachOSection("__TEXT", "__literal16",
 105                              MachO::S_16BYTE_LITERALS,
 106                              SectionKind::getMergeableConst16());
 107
 108   ReadOnlySection  // .const
 109     = Ctx->getMachOSection("__TEXT", "__const", 0,
 110                            SectionKind::getReadOnly());
 111
 112   TextCoalSection
 113     = Ctx->getMachOSection("__TEXT", "__textcoal_nt",
 114                            MachO::S_COALESCED |
 115                            MachO::S_ATTR_PURE_INSTRUCTIONS,
 116                            SectionKind::getText());
 117   ConstTextCoalSection
 118     = Ctx->getMachOSection("__TEXT", "__const_coal",
 119                            MachO::S_COALESCED,
 120                            SectionKind::getReadOnly());
 121   ConstDataSection  // .const_data
 122     = Ctx->getMachOSection("__DATA", "__const", 0,
 123                            SectionKind::getReadOnlyWithRel());
 124   DataCoalSection
 125     = Ctx->getMachOSection("__DATA","__datacoal_nt",
 126                            MachO::S_COALESCED,
 127                            SectionKind::getDataRel());
 128   DataCommonSection
 129     = Ctx->getMachOSection("__DATA","__common",
 130                            MachO::S_ZEROFILL,
 131                            SectionKind::getBSS());
 132   DataBSSSection
 133     = Ctx->getMachOSection("__DATA","__bss", MachO::S_ZEROFILL,
 134                            SectionKind::getBSS());
 135
 136
 137   LazySymbolPointerSection
 138     = Ctx->getMachOSection("__DATA", "__la_symbol_ptr",
 139                            MachO::S_LAZY_SYMBOL_POINTERS,
 140                            SectionKind::getMetadata());
 141   NonLazySymbolPointerSection
 142     = Ctx->getMachOSection("__DATA", "__nl_symbol_ptr",
 143                            MachO::S_NON_LAZY_SYMBOL_POINTERS,
 144                            SectionKind::getMetadata());
 145
 146   if (RelocM == Reloc::Static) {
 147     StaticCtorSection
 148       = Ctx->getMachOSection("__TEXT", "__constructor", 0,
 149                              SectionKind::getDataRel());
 150     StaticDtorSection
 151       = Ctx->getMachOSection("__TEXT", "__destructor", 0,
 152                              SectionKind::getDataRel());
 153   } else {
 154     StaticCtorSection
 155       = Ctx->getMachOSection("__DATA", "__mod_init_func",
 156                              MachO::S_MOD_INIT_FUNC_POINTERS,
 157                              SectionKind::getDataRel());
 158     StaticDtorSection
 159       = Ctx->getMachOSection("__DATA", "__mod_term_func",
 160                              MachO::S_MOD_TERM_FUNC_POINTERS,
 161                              SectionKind::getDataRel());
 162   }
 163
 164   // Exception Handling.
 165   LSDASection = Ctx->getMachOSection("__TEXT", "__gcc_except_tab", 0,
 166                                      SectionKind::getReadOnlyWithRel());
 167
 168   COFFDebugSymbolsSection = nullptr;
 169
 170   if (useCompactUnwind(T)) {
 171     CompactUnwindSection =
 172         Ctx->getMachOSection("__LD", "__compact_unwind", MachO::S_ATTR_DEBUG,
 173                              SectionKind::getReadOnly());
 174
 175     if (T.getArch() == Triple::x86_64 || T.getArch() == Triple::x86)
 176       CompactUnwindDwarfEHFrameOnly = 0x04000000;
 177     else if (T.getArch() == Triple::arm64 || T.getArch() == Triple::aarch64)
 178       CompactUnwindDwarfEHFrameOnly = 0x03000000;
 179   }
 180
 181   // Debug Information.
 182   DwarfAccelNamesSection =
 183     Ctx->getMachOSection("__DWARF", "__apple_names",
 184                          MachO::S_ATTR_DEBUG,
 185                          SectionKind::getMetadata());
 186   DwarfAccelObjCSection =
 187     Ctx->getMachOSection("__DWARF", "__apple_objc",
 188                          MachO::S_ATTR_DEBUG,
 189                          SectionKind::getMetadata());
 190   // 16 character section limit...
 191   DwarfAccelNamespaceSection =
 192     Ctx->getMachOSection("__DWARF", "__apple_namespac",
 193                          MachO::S_ATTR_DEBUG,
 194                          SectionKind::getMetadata());
 195   DwarfAccelTypesSection =
 196     Ctx->getMachOSection("__DWARF", "__apple_types",
 197                          MachO::S_ATTR_DEBUG,
 198                          SectionKind::getMetadata());
 199
 200   DwarfAbbrevSection =
 201     Ctx->getMachOSection("__DWARF", "__debug_abbrev",
 202                          MachO::S_ATTR_DEBUG,
 203                          SectionKind::getMetadata());
 204   DwarfInfoSection =
 205     Ctx->getMachOSection("__DWARF", "__debug_info",
 206                          MachO::S_ATTR_DEBUG,
 207                          SectionKind::getMetadata());
 208   DwarfLineSection =
 209     Ctx->getMachOSection("__DWARF", "__debug_line",
 210                          MachO::S_ATTR_DEBUG,
 211                          SectionKind::getMetadata());
 212   DwarfFrameSection =
 213     Ctx->getMachOSection("__DWARF", "__debug_frame",
 214                          MachO::S_ATTR_DEBUG,
 215                          SectionKind::getMetadata());
 216   DwarfPubNamesSection =
 217     Ctx->getMachOSection("__DWARF", "__debug_pubnames",
 218                          MachO::S_ATTR_DEBUG,
 219                          SectionKind::getMetadata());
 220   DwarfPubTypesSection =
 221     Ctx->getMachOSection("__DWARF", "__debug_pubtypes",
 222                          MachO::S_ATTR_DEBUG,
 223                          SectionKind::getMetadata());
 224   DwarfGnuPubNamesSection =
 225     Ctx->getMachOSection("__DWARF", "__debug_gnu_pubn",
 226                          MachO::S_ATTR_DEBUG,
 227                          SectionKind::getMetadata());
 228   DwarfGnuPubTypesSection =
 229     Ctx->getMachOSection("__DWARF", "__debug_gnu_pubt",
 230                          MachO::S_ATTR_DEBUG,
 231                          SectionKind::getMetadata());
 232   DwarfStrSection =
 233     Ctx->getMachOSection("__DWARF", "__debug_str",
 234                          MachO::S_ATTR_DEBUG,
 235                          SectionKind::getMetadata());
 236   DwarfLocSection =
 237     Ctx->getMachOSection("__DWARF", "__debug_loc",
 238                          MachO::S_ATTR_DEBUG,
 239                          SectionKind::getMetadata());
 240   DwarfARangesSection =
 241     Ctx->getMachOSection("__DWARF", "__debug_aranges",
 242                          MachO::S_ATTR_DEBUG,
 243                          SectionKind::getMetadata());
 244   DwarfRangesSection =
 245     Ctx->getMachOSection("__DWARF", "__debug_ranges",
 246                          MachO::S_ATTR_DEBUG,
 247                          SectionKind::getMetadata());
 248   DwarfMacroInfoSection =
 249     Ctx->getMachOSection("__DWARF", "__debug_macinfo",
 250                          MachO::S_ATTR_DEBUG,
 251                          SectionKind::getMetadata());
 252   DwarfDebugInlineSection =
 253     Ctx->getMachOSection("__DWARF", "__debug_inlined",
 254                          MachO::S_ATTR_DEBUG,
 255                          SectionKind::getMetadata());
 256   StackMapSection =
 257     Ctx->getMachOSection("__LLVM_STACKMAPS", "__llvm_stackmaps", 0,
 258                          SectionKind::getMetadata());
 259
 260   TLSExtraDataSection = TLSTLVSection;
 261 }
 262
 263 void MCObjectFileInfo::InitELFMCObjectFileInfo(Triple T) {
 264   switch (T.getArch()) {
 265   case Triple::mips:
 266   case Triple::mipsel:
 267     FDECFIEncoding = dwarf::DW_EH_PE_sdata4;
 268     break;
 269   case Triple::mips64:
 270   case Triple::mips64el:
 271     FDECFIEncoding = dwarf::DW_EH_PE_sdata8;
 272     break;
 273   default:
 274     FDECFIEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 275     break;
 276   }
 277
 278   switch (T.getArch()) {
 279   case Triple::arm:
 280   case Triple::armeb:
 281   case Triple::thumb:
 282   case Triple::thumbeb:
 283     if (Ctx->getAsmInfo()->getExceptionHandlingType() == ExceptionHandling::ARM)
 284       break;
 285     // Fallthrough if not using EHABI
 286   case Triple::x86:
 287     PersonalityEncoding = (RelocM == Reloc::PIC_)
 288      ? dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
 289      : dwarf::DW_EH_PE_absptr;
 290     LSDAEncoding = (RelocM == Reloc::PIC_)
 291       ? dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
 292       : dwarf::DW_EH_PE_absptr;
 293     TTypeEncoding = (RelocM == Reloc::PIC_)
 294      ? dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4
 295      : dwarf::DW_EH_PE_absptr;
 296     break;
 297   case Triple::x86_64:
 298     if (RelocM == Reloc::PIC_) {
 299       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 300         ((CMModel == CodeModel::Small || CMModel == CodeModel::Medium)
 301          ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
 302       LSDAEncoding = dwarf::DW_EH_PE_pcrel |
 303         (CMModel == CodeModel::Small
 304          ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
 305       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 306         ((CMModel == CodeModel::Small || CMModel == CodeModel::Medium)
 307          ? dwarf::DW_EH_PE_sdata4 : dwarf::DW_EH_PE_sdata8);
 308     } else {
 309       PersonalityEncoding =
 310         (CMModel == CodeModel::Small || CMModel == CodeModel::Medium)
 311         ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
 312       LSDAEncoding = (CMModel == CodeModel::Small)
 313         ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
 314       TTypeEncoding = (CMModel == CodeModel::Small)
 315         ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_absptr;
 316     }
 317     break;
 318   case Triple::aarch64:
 319   case Triple::aarch64_be:
 320   case Triple::arm64:
 321   case Triple::arm64_be:
 322     // The small model guarantees static code/data size < 4GB, but not where it
 323     // will be in memory. Most of these could end up >2GB away so even a signed
 324     // pc-relative 32-bit address is insufficient, theoretically.
 325     if (RelocM == Reloc::PIC_) {
 326       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 327         dwarf::DW_EH_PE_sdata8;
 328       LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata8;
 329       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 330         dwarf::DW_EH_PE_sdata8;
 331     } else {
 332       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 333       LSDAEncoding = dwarf::DW_EH_PE_absptr;
 334       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 335     }
 336     break;
 337   case Triple::mips:
 338   case Triple::mipsel:
 339     // MIPS uses indirect pointer to refer personality functions, so that the
 340     // eh_frame section can be read-only.  DW.ref.personality will be generated
 341     // for relocation.
 342     PersonalityEncoding = dwarf::DW_EH_PE_indirect;
 343     break;
 344   case Triple::ppc64:
 345   case Triple::ppc64le:
 346     PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 347       dwarf::DW_EH_PE_udata8;
 348     LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_udata8;
 349     TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 350       dwarf::DW_EH_PE_udata8;
 351     break;
 352   case Triple::sparc:
 353     if (RelocM == Reloc::PIC_) {
 354       LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 355       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 356         dwarf::DW_EH_PE_sdata4;
 357       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 358         dwarf::DW_EH_PE_sdata4;
 359     } else {
 360       LSDAEncoding = dwarf::DW_EH_PE_absptr;
 361       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 362       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 363     }
 364     break;
 365   case Triple::sparcv9:
 366     LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 367     if (RelocM == Reloc::PIC_) {
 368       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 369         dwarf::DW_EH_PE_sdata4;
 370       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 371         dwarf::DW_EH_PE_sdata4;
 372     } else {
 373       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 374       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 375     }
 376     break;
 377   case Triple::systemz:
 378     // All currently-defined code models guarantee that 4-byte PC-relative
 379     // values will be in range.
 380     if (RelocM == Reloc::PIC_) {
 381       PersonalityEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 382         dwarf::DW_EH_PE_sdata4;
 383       LSDAEncoding = dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4;
 384       TTypeEncoding = dwarf::DW_EH_PE_indirect | dwarf::DW_EH_PE_pcrel |
 385         dwarf::DW_EH_PE_sdata4;
 386     } else {
 387       PersonalityEncoding = dwarf::DW_EH_PE_absptr;
 388       LSDAEncoding = dwarf::DW_EH_PE_absptr;
 389       TTypeEncoding = dwarf::DW_EH_PE_absptr;
 390     }
 391     break;
 392   default:
 393     break;
 394   }
 395
 396   // Solaris requires different flags for .eh_frame to seemingly every other
 397   // platform.
 398   EHSectionType = ELF::SHT_PROGBITS;
 399   EHSectionFlags = ELF::SHF_ALLOC;
 400   if (T.getOS() == Triple::Solaris) {
 401     if (T.getArch() == Triple::x86_64)
 402       EHSectionType = ELF::SHT_X86_64_UNWIND;
 403     else
 404       EHSectionFlags |= ELF::SHF_WRITE;
 405   }
 406
 407
 408   // ELF
 409   BSSSection =
 410     Ctx->getELFSection(".bss", ELF::SHT_NOBITS,
 411                        ELF::SHF_WRITE | ELF::SHF_ALLOC,
 412                        SectionKind::getBSS());
 413
 414   TextSection =
 415     Ctx->getELFSection(".text", ELF::SHT_PROGBITS,
 416                        ELF::SHF_EXECINSTR |
 417                        ELF::SHF_ALLOC,
 418                        SectionKind::getText());
 419
 420   DataSection =
 421     Ctx->getELFSection(".data", ELF::SHT_PROGBITS,
 422                        ELF::SHF_WRITE |ELF::SHF_ALLOC,
 423                        SectionKind::getDataRel());
 424
 425   ReadOnlySection =
 426     Ctx->getELFSection(".rodata", ELF::SHT_PROGBITS,
 427                        ELF::SHF_ALLOC,
 428                        SectionKind::getReadOnly());
 429
 430   TLSDataSection =
 431     Ctx->getELFSection(".tdata", ELF::SHT_PROGBITS,
 432                        ELF::SHF_ALLOC | ELF::SHF_TLS |
 433                        ELF::SHF_WRITE,
 434                        SectionKind::getThreadData());
 435
 436   TLSBSSSection =
 437     Ctx->getELFSection(".tbss", ELF::SHT_NOBITS,
 438                        ELF::SHF_ALLOC | ELF::SHF_TLS |
 439                        ELF::SHF_WRITE,
 440                        SectionKind::getThreadBSS());
 441
 442   DataRelSection =
 443     Ctx->getELFSection(".data.rel", ELF::SHT_PROGBITS,
 444                        ELF::SHF_ALLOC |ELF::SHF_WRITE,
 445                        SectionKind::getDataRel());
 446
 447   DataRelLocalSection =
 448     Ctx->getELFSection(".data.rel.local", ELF::SHT_PROGBITS,
 449                        ELF::SHF_ALLOC |ELF::SHF_WRITE,
 450                        SectionKind::getDataRelLocal());
 451
 452   DataRelROSection =
 453     Ctx->getELFSection(".data.rel.ro", ELF::SHT_PROGBITS,
 454                        ELF::SHF_ALLOC |ELF::SHF_WRITE,
 455                        SectionKind::getReadOnlyWithRel());
 456
 457   DataRelROLocalSection =
 458     Ctx->getELFSection(".data.rel.ro.local", ELF::SHT_PROGBITS,
 459                        ELF::SHF_ALLOC |ELF::SHF_WRITE,
 460                        SectionKind::getReadOnlyWithRelLocal());
 461
 462   MergeableConst4Section =
 463     Ctx->getELFSection(".rodata.cst4", ELF::SHT_PROGBITS,
 464                        ELF::SHF_ALLOC |ELF::SHF_MERGE,
 465                        SectionKind::getMergeableConst4());
 466
 467   MergeableConst8Section =
 468     Ctx->getELFSection(".rodata.cst8", ELF::SHT_PROGBITS,
 469                        ELF::SHF_ALLOC |ELF::SHF_MERGE,
 470                        SectionKind::getMergeableConst8());
 471
 472   MergeableConst16Section =
 473     Ctx->getELFSection(".rodata.cst16", ELF::SHT_PROGBITS,
 474                        ELF::SHF_ALLOC |ELF::SHF_MERGE,
 475                        SectionKind::getMergeableConst16());
 476
 477   StaticCtorSection =
 478     Ctx->getELFSection(".ctors", ELF::SHT_PROGBITS,
 479                        ELF::SHF_ALLOC |ELF::SHF_WRITE,
 480                        SectionKind::getDataRel());
 481
 482   StaticDtorSection =
 483     Ctx->getELFSection(".dtors", ELF::SHT_PROGBITS,
 484                        ELF::SHF_ALLOC |ELF::SHF_WRITE,
 485                        SectionKind::getDataRel());
 486
 487   // Exception Handling Sections.
 488
 489   // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
 490   // it contains relocatable pointers.  In PIC mode, this is probably a big
 491   // runtime hit for C++ apps.  Either the contents of the LSDA need to be
 492   // adjusted or this should be a data section.
 493   LSDASection =
 494     Ctx->getELFSection(".gcc_except_table", ELF::SHT_PROGBITS,
 495                        ELF::SHF_ALLOC,
 496                        SectionKind::getReadOnly());
 497
 498   COFFDebugSymbolsSection = nullptr;
 499
 500   // Debug Info Sections.
 501   DwarfAbbrevSection =
 502     Ctx->getELFSection(".debug_abbrev", ELF::SHT_PROGBITS, 0,
 503                        SectionKind::getMetadata());
 504   DwarfInfoSection =
 505     Ctx->getELFSection(".debug_info", ELF::SHT_PROGBITS, 0,
 506                        SectionKind::getMetadata());
 507   DwarfLineSection =
 508     Ctx->getELFSection(".debug_line", ELF::SHT_PROGBITS, 0,
 509                        SectionKind::getMetadata());
 510   DwarfFrameSection =
 511     Ctx->getELFSection(".debug_frame", ELF::SHT_PROGBITS, 0,
 512                        SectionKind::getMetadata());
 513   DwarfPubNamesSection =
 514     Ctx->getELFSection(".debug_pubnames", ELF::SHT_PROGBITS, 0,
 515                        SectionKind::getMetadata());
 516   DwarfPubTypesSection =
 517     Ctx->getELFSection(".debug_pubtypes", ELF::SHT_PROGBITS, 0,
 518                        SectionKind::getMetadata());
 519   DwarfGnuPubNamesSection =
 520     Ctx->getELFSection(".debug_gnu_pubnames", ELF::SHT_PROGBITS, 0,
 521                        SectionKind::getMetadata());
 522   DwarfGnuPubTypesSection =
 523     Ctx->getELFSection(".debug_gnu_pubtypes", ELF::SHT_PROGBITS, 0,
 524                        SectionKind::getMetadata());
 525   DwarfStrSection =
 526     Ctx->getELFSection(".debug_str", ELF::SHT_PROGBITS,
 527                        ELF::SHF_MERGE | ELF::SHF_STRINGS,
 528                        SectionKind::getMergeable1ByteCString());
 529   DwarfLocSection =
 530     Ctx->getELFSection(".debug_loc", ELF::SHT_PROGBITS, 0,
 531                        SectionKind::getMetadata());
 532   DwarfARangesSection =
 533     Ctx->getELFSection(".debug_aranges", ELF::SHT_PROGBITS, 0,
 534                        SectionKind::getMetadata());
 535   DwarfRangesSection =
 536     Ctx->getELFSection(".debug_ranges", ELF::SHT_PROGBITS, 0,
 537                        SectionKind::getMetadata());
 538   DwarfMacroInfoSection =
 539     Ctx->getELFSection(".debug_macinfo", ELF::SHT_PROGBITS, 0,
 540                        SectionKind::getMetadata());
 541
 542   // DWARF5 Experimental Debug Info
 543
 544   // Accelerator Tables
 545   DwarfAccelNamesSection =
 546     Ctx->getELFSection(".apple_names", ELF::SHT_PROGBITS, 0,
 547                        SectionKind::getMetadata());
 548   DwarfAccelObjCSection =
 549     Ctx->getELFSection(".apple_objc", ELF::SHT_PROGBITS, 0,
 550                        SectionKind::getMetadata());
 551   DwarfAccelNamespaceSection =
 552     Ctx->getELFSection(".apple_namespaces", ELF::SHT_PROGBITS, 0,
 553                        SectionKind::getMetadata());
 554   DwarfAccelTypesSection =
 555     Ctx->getELFSection(".apple_types", ELF::SHT_PROGBITS, 0,
 556                        SectionKind::getMetadata());
 557
 558   // Fission Sections
 559   DwarfInfoDWOSection =
 560     Ctx->getELFSection(".debug_info.dwo", ELF::SHT_PROGBITS, 0,
 561                        SectionKind::getMetadata());
 562   DwarfAbbrevDWOSection =
 563     Ctx->getELFSection(".debug_abbrev.dwo", ELF::SHT_PROGBITS, 0,
 564                        SectionKind::getMetadata());
 565   DwarfStrDWOSection =
 566     Ctx->getELFSection(".debug_str.dwo", ELF::SHT_PROGBITS,
 567                        ELF::SHF_MERGE | ELF::SHF_STRINGS,
 568                        SectionKind::getMergeable1ByteCString());
 569   DwarfLineDWOSection =
 570     Ctx->getELFSection(".debug_line.dwo", ELF::SHT_PROGBITS, 0,
 571                        SectionKind::getMetadata());
 572   DwarfLocDWOSection =
 573     Ctx->getELFSection(".debug_loc.dwo", ELF::SHT_PROGBITS, 0,
 574                        SectionKind::getMetadata());
 575   DwarfStrOffDWOSection =
 576     Ctx->getELFSection(".debug_str_offsets.dwo", ELF::SHT_PROGBITS, 0,
 577                        SectionKind::getMetadata());
 578   DwarfAddrSection =
 579     Ctx->getELFSection(".debug_addr", ELF::SHT_PROGBITS, 0,
 580                        SectionKind::getMetadata());
 581 }
 582
 583
 584 void MCObjectFileInfo::InitCOFFMCObjectFileInfo(Triple T) {
 585   bool IsWoA = T.getArch() == Triple::arm || T.getArch() == Triple::thumb;
 586
 587   // The object file format cannot represent common symbols with explicit
 588   // alignments.
 589   CommDirectiveSupportsAlignment = false;
 590
 591   // COFF
 592   BSSSection =
 593     Ctx->getCOFFSection(".bss",
 594                         COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
 595                         COFF::IMAGE_SCN_MEM_READ |
 596                         COFF::IMAGE_SCN_MEM_WRITE,
 597                         SectionKind::getBSS());
 598   TextSection =
 599     Ctx->getCOFFSection(".text",
 600                         (IsWoA ? COFF::IMAGE_SCN_MEM_16BIT
 601                                : (COFF::SectionCharacteristics)0) |
 602                         COFF::IMAGE_SCN_CNT_CODE |
 603                         COFF::IMAGE_SCN_MEM_EXECUTE |
 604                         COFF::IMAGE_SCN_MEM_READ,
 605                         SectionKind::getText());
 606   DataSection =
 607     Ctx->getCOFFSection(".data",
 608                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 609                         COFF::IMAGE_SCN_MEM_READ |
 610                         COFF::IMAGE_SCN_MEM_WRITE,
 611                         SectionKind::getDataRel());
 612   ReadOnlySection =
 613     Ctx->getCOFFSection(".rdata",
 614                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 615                         COFF::IMAGE_SCN_MEM_READ,
 616                         SectionKind::getReadOnly());
 617
 618   if (T.isKnownWindowsMSVCEnvironment() || T.isWindowsItaniumEnvironment()) {
 619     StaticCtorSection =
 620       Ctx->getCOFFSection(".CRT$XCU",
 621                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 622                           COFF::IMAGE_SCN_MEM_READ,
 623                           SectionKind::getReadOnly());
 624     StaticDtorSection =
 625       Ctx->getCOFFSection(".CRT$XTX",
 626                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 627                           COFF::IMAGE_SCN_MEM_READ,
 628                           SectionKind::getReadOnly());
 629   } else {
 630     StaticCtorSection =
 631       Ctx->getCOFFSection(".ctors",
 632                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 633                           COFF::IMAGE_SCN_MEM_READ |
 634                           COFF::IMAGE_SCN_MEM_WRITE,
 635                           SectionKind::getDataRel());
 636     StaticDtorSection =
 637       Ctx->getCOFFSection(".dtors",
 638                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 639                           COFF::IMAGE_SCN_MEM_READ |
 640                           COFF::IMAGE_SCN_MEM_WRITE,
 641                           SectionKind::getDataRel());
 642   }
 643
 644   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
 645   // though it contains relocatable pointers.  In PIC mode, this is probably a
 646   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
 647   // adjusted or this should be a data section.
 648   assert(T.isOSWindows() && "Windows is the only supported COFF target");
 649   if (T.getArch() == Triple::x86_64) {
 650     // On Windows 64 with SEH, the LSDA is emitted into the .xdata section
 651     LSDASection = 0;
 652   } else {
 653     LSDASection = Ctx->getCOFFSection(".gcc_except_table",
 654                                       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 655                                           COFF::IMAGE_SCN_MEM_READ,
 656                                       SectionKind::getReadOnly());
 657   }
 658
 659   // Debug info.
 660   COFFDebugSymbolsSection =
 661     Ctx->getCOFFSection(".debug$S",
 662                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 663                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 664                         COFF::IMAGE_SCN_MEM_READ,
 665                         SectionKind::getMetadata());
 666
 667   DwarfAbbrevSection =
 668     Ctx->getCOFFSection(".debug_abbrev",
 669                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 670                         COFF::IMAGE_SCN_MEM_READ,
 671                         SectionKind::getMetadata());
 672   DwarfInfoSection =
 673     Ctx->getCOFFSection(".debug_info",
 674                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 675                         COFF::IMAGE_SCN_MEM_READ,
 676                         SectionKind::getMetadata());
 677   DwarfLineSection =
 678     Ctx->getCOFFSection(".debug_line",
 679                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 680                         COFF::IMAGE_SCN_MEM_READ,
 681                         SectionKind::getMetadata());
 682   DwarfFrameSection =
 683     Ctx->getCOFFSection(".debug_frame",
 684                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 685                         COFF::IMAGE_SCN_MEM_READ,
 686                         SectionKind::getMetadata());
 687   DwarfPubNamesSection =
 688     Ctx->getCOFFSection(".debug_pubnames",
 689                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 690                         COFF::IMAGE_SCN_MEM_READ,
 691                         SectionKind::getMetadata());
 692   DwarfPubTypesSection =
 693     Ctx->getCOFFSection(".debug_pubtypes",
 694                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 695                         COFF::IMAGE_SCN_MEM_READ,
 696                         SectionKind::getMetadata());
 697   DwarfGnuPubNamesSection =
 698     Ctx->getCOFFSection(".debug_gnu_pubnames",
 699                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 700                         COFF::IMAGE_SCN_MEM_READ,
 701                         SectionKind::getMetadata());
 702   DwarfGnuPubTypesSection =
 703     Ctx->getCOFFSection(".debug_gnu_pubtypes",
 704                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 705                         COFF::IMAGE_SCN_MEM_READ,
 706                         SectionKind::getMetadata());
 707   DwarfStrSection =
 708     Ctx->getCOFFSection(".debug_str",
 709                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 710                         COFF::IMAGE_SCN_MEM_READ,
 711                         SectionKind::getMetadata());
 712   DwarfLocSection =
 713     Ctx->getCOFFSection(".debug_loc",
 714                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 715                         COFF::IMAGE_SCN_MEM_READ,
 716                         SectionKind::getMetadata());
 717   DwarfARangesSection =
 718     Ctx->getCOFFSection(".debug_aranges",
 719                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 720                         COFF::IMAGE_SCN_MEM_READ,
 721                         SectionKind::getMetadata());
 722   DwarfRangesSection =
 723     Ctx->getCOFFSection(".debug_ranges",
 724                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 725                         COFF::IMAGE_SCN_MEM_READ,
 726                         SectionKind::getMetadata());
 727   DwarfMacroInfoSection =
 728     Ctx->getCOFFSection(".debug_macinfo",
 729                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 730                         COFF::IMAGE_SCN_MEM_READ,
 731                         SectionKind::getMetadata());
 732   DwarfInfoDWOSection =
 733       Ctx->getCOFFSection(".debug_info.dwo",
 734                           COFF::IMAGE_SCN_MEM_DISCARDABLE |
 735                           COFF::IMAGE_SCN_MEM_READ,
 736                           SectionKind::getMetadata());
 737   DwarfAbbrevDWOSection =
 738       Ctx->getCOFFSection(".debug_abbrev.dwo",
 739                           COFF::IMAGE_SCN_MEM_DISCARDABLE |
 740                           COFF::IMAGE_SCN_MEM_READ,
 741                           SectionKind::getMetadata());
 742   DwarfStrDWOSection =
 743       Ctx->getCOFFSection(".debug_str.dwo",
 744                           COFF::IMAGE_SCN_MEM_DISCARDABLE |
 745                           COFF::IMAGE_SCN_MEM_READ,
 746                           SectionKind::getMetadata());
 747   DwarfLineDWOSection =
 748       Ctx->getCOFFSection(".debug_line.dwo",
 749                           COFF::IMAGE_SCN_MEM_DISCARDABLE |
 750                           COFF::IMAGE_SCN_MEM_READ,
 751                           SectionKind::getMetadata());
 752   DwarfLocDWOSection =
 753       Ctx->getCOFFSection(".debug_loc.dwo",
 754                           COFF::IMAGE_SCN_MEM_DISCARDABLE |
 755                           COFF::IMAGE_SCN_MEM_READ,
 756                           SectionKind::getMetadata());
 757   DwarfStrOffDWOSection =
 758       Ctx->getCOFFSection(".debug_str_offsets.dwo",
 759                           COFF::IMAGE_SCN_MEM_DISCARDABLE |
 760                           COFF::IMAGE_SCN_MEM_READ,
 761                           SectionKind::getMetadata());
 762
 763   DwarfAddrSection =
 764     Ctx->getCOFFSection(".debug_addr",
 765                         COFF::IMAGE_SCN_MEM_DISCARDABLE |
 766                         COFF::IMAGE_SCN_MEM_READ,
 767                         SectionKind::getMetadata());
 768
 769   DrectveSection =
 770     Ctx->getCOFFSection(".drectve",
 771                         COFF::IMAGE_SCN_LNK_INFO |
 772                         COFF::IMAGE_SCN_LNK_REMOVE,
 773                         SectionKind::getMetadata());
 774
 775   PDataSection =
 776     Ctx->getCOFFSection(".pdata",
 777                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 778                         COFF::IMAGE_SCN_MEM_READ,
 779                         SectionKind::getDataRel());
 780
 781   XDataSection =
 782     Ctx->getCOFFSection(".xdata",
 783                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 784                         COFF::IMAGE_SCN_MEM_READ,
 785                         SectionKind::getDataRel());
 786
 787   TLSDataSection =
 788     Ctx->getCOFFSection(".tls$",
 789                         COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 790                         COFF::IMAGE_SCN_MEM_READ |
 791                         COFF::IMAGE_SCN_MEM_WRITE,
 792                         SectionKind::getDataRel());
 793 }
 794
 795 void MCObjectFileInfo::InitMCObjectFileInfo(StringRef TT, Reloc::Model relocm,
 796                                             CodeModel::Model cm,
 797                                             MCContext &ctx) {
 798   RelocM = relocm;
 799   CMModel = cm;
 800   Ctx = &ctx;
 801
 802   // Common.
 803   CommDirectiveSupportsAlignment = true;
 804   SupportsWeakOmittedEHFrame = true;
 805   IsFunctionEHFrameSymbolPrivate = 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   Triple T(TT);
 821   Triple::ArchType Arch = T.getArch();
 822   // FIXME: Checking for Arch here to filter out bogus triples such as
 823   // cellspu-apple-darwin. Perhaps we should fix in Triple?
 824   if ((Arch == Triple::x86 || Arch == Triple::x86_64 ||
 825        Arch == Triple::arm || Arch == Triple::thumb ||
 826        Arch == Triple::arm64 || Arch == Triple::aarch64 ||
 827        Arch == Triple::ppc || Arch == Triple::ppc64 ||
 828        Arch == Triple::UnknownArch) &&
 829       (T.isOSDarwin() || T.isOSBinFormatMachO())) {
 830     Env = IsMachO;
 831     InitMachOMCObjectFileInfo(T);
 832   } else if ((Arch == Triple::x86 || Arch == Triple::x86_64 ||
 833               Arch == Triple::arm || Arch == Triple::thumb) &&
 834              (T.isOSWindows() && T.getObjectFormat() == Triple::COFF)) {
 835     Env = IsCOFF;
 836     InitCOFFMCObjectFileInfo(T);
 837   } else {
 838     Env = IsELF;
 839     InitELFMCObjectFileInfo(T);
 840   }
 841 }
 842
 843 const MCSection *MCObjectFileInfo::getDwarfTypesSection(uint64_t Hash) const {
 844   return Ctx->getELFSection(".debug_types", ELF::SHT_PROGBITS, ELF::SHF_GROUP,
 845                             SectionKind::getMetadata(), 0, utostr(Hash));
 846 }
 847
 848 const MCSection *
 849 MCObjectFileInfo::getDwarfTypesDWOSection(uint64_t Hash) const {
 850   return Ctx->getELFSection(".debug_types.dwo", ELF::SHT_PROGBITS,
 851                             ELF::SHF_GROUP, SectionKind::getMetadata(), 0,
 852                             utostr(Hash));
 853 }
 854
 855 void MCObjectFileInfo::InitEHFrameSection() {
 856   if (Env == IsMachO)
 857     EHFrameSection =
 858       Ctx->getMachOSection("__TEXT", "__eh_frame",
 859                            MachO::S_COALESCED |
 860                            MachO::S_ATTR_NO_TOC |
 861                            MachO::S_ATTR_STRIP_STATIC_SYMS |
 862                            MachO::S_ATTR_LIVE_SUPPORT,
 863                            SectionKind::getReadOnly());
 864   else if (Env == IsELF)
 865     EHFrameSection =
 866       Ctx->getELFSection(".eh_frame", EHSectionType,
 867                          EHSectionFlags,
 868                          SectionKind::getDataRel());
 869   else
 870     EHFrameSection =
 871       Ctx->getCOFFSection(".eh_frame",
 872                           COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 873                           COFF::IMAGE_SCN_MEM_READ |
 874                           COFF::IMAGE_SCN_MEM_WRITE,
 875                           SectionKind::getDataRel());
 876 }