lib/CodeGen/TargetLoweringObjectFileImpl.cpp

   1 //===-- llvm/CodeGen/TargetLoweringObjectFileImpl.cpp - Object File Info --===//
   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 // This file implements classes used to handle lowerings specific to common
  11 // object file formats.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
  16 #include "llvm/Constants.h"
  17 #include "llvm/DerivedTypes.h"
  18 #include "llvm/Function.h"
  19 #include "llvm/GlobalVariable.h"
  20 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
  21 #include "llvm/MC/MCContext.h"
  22 #include "llvm/MC/MCExpr.h"
  23 #include "llvm/MC/MCSectionMachO.h"
  24 #include "llvm/MC/MCSectionELF.h"
  25 #include "llvm/MC/MCSectionCOFF.h"
  26 #include "llvm/MC/MCStreamer.h"
  27 #include "llvm/MC/MCSymbol.h"
  28 #include "llvm/Target/Mangler.h"
  29 #include "llvm/Target/TargetData.h"
  30 #include "llvm/Target/TargetMachine.h"
  31 #include "llvm/Target/TargetOptions.h"
  32 #include "llvm/Support/Dwarf.h"
  33 #include "llvm/Support/ELF.h"
  34 #include "llvm/Support/ErrorHandling.h"
  35 #include "llvm/Support/raw_ostream.h"
  36 #include "llvm/ADT/SmallString.h"
  37 #include "llvm/ADT/StringExtras.h"
  38 #include "llvm/ADT/Triple.h"
  39 using namespace llvm;
  40 using namespace dwarf;
  41
  42 //===----------------------------------------------------------------------===//
  43 //                                  ELF
  44 //===----------------------------------------------------------------------===//
  45
  46 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
  47                                              const TargetMachine &TM) {
  48   TargetLoweringObjectFile::Initialize(Ctx, TM);
  49
  50   BSSSection =
  51     getContext().getELFSection(".bss", ELF::SHT_NOBITS,
  52                                ELF::SHF_WRITE |ELF::SHF_ALLOC,
  53                                SectionKind::getBSS());
  54
  55   TextSection =
  56     getContext().getELFSection(".text", ELF::SHT_PROGBITS,
  57                                ELF::SHF_EXECINSTR |
  58                                ELF::SHF_ALLOC,
  59                                SectionKind::getText());
  60
  61   DataSection =
  62     getContext().getELFSection(".data", ELF::SHT_PROGBITS,
  63                                ELF::SHF_WRITE |ELF::SHF_ALLOC,
  64                                SectionKind::getDataRel());
  65
  66   ReadOnlySection =
  67     getContext().getELFSection(".rodata", ELF::SHT_PROGBITS,
  68                                ELF::SHF_ALLOC,
  69                                SectionKind::getReadOnly());
  70
  71   TLSDataSection =
  72     getContext().getELFSection(".tdata", ELF::SHT_PROGBITS,
  73                                ELF::SHF_ALLOC | ELF::SHF_TLS |
  74                                ELF::SHF_WRITE,
  75                                SectionKind::getThreadData());
  76
  77   TLSBSSSection =
  78     getContext().getELFSection(".tbss", ELF::SHT_NOBITS,
  79                                ELF::SHF_ALLOC | ELF::SHF_TLS |
  80                                ELF::SHF_WRITE,
  81                                SectionKind::getThreadBSS());
  82
  83   DataRelSection =
  84     getContext().getELFSection(".data.rel", ELF::SHT_PROGBITS,
  85                                ELF::SHF_ALLOC |ELF::SHF_WRITE,
  86                                SectionKind::getDataRel());
  87
  88   DataRelLocalSection =
  89     getContext().getELFSection(".data.rel.local", ELF::SHT_PROGBITS,
  90                                ELF::SHF_ALLOC |ELF::SHF_WRITE,
  91                                SectionKind::getDataRelLocal());
  92
  93   DataRelROSection =
  94     getContext().getELFSection(".data.rel.ro", ELF::SHT_PROGBITS,
  95                                ELF::SHF_ALLOC |ELF::SHF_WRITE,
  96                                SectionKind::getReadOnlyWithRel());
  97
  98   DataRelROLocalSection =
  99     getContext().getELFSection(".data.rel.ro.local", ELF::SHT_PROGBITS,
 100                                ELF::SHF_ALLOC |ELF::SHF_WRITE,
 101                                SectionKind::getReadOnlyWithRelLocal());
 102
 103   MergeableConst4Section =
 104     getContext().getELFSection(".rodata.cst4", ELF::SHT_PROGBITS,
 105                                ELF::SHF_ALLOC |ELF::SHF_MERGE,
 106                                SectionKind::getMergeableConst4());
 107
 108   MergeableConst8Section =
 109     getContext().getELFSection(".rodata.cst8", ELF::SHT_PROGBITS,
 110                                ELF::SHF_ALLOC |ELF::SHF_MERGE,
 111                                SectionKind::getMergeableConst8());
 112
 113   MergeableConst16Section =
 114     getContext().getELFSection(".rodata.cst16", ELF::SHT_PROGBITS,
 115                                ELF::SHF_ALLOC |ELF::SHF_MERGE,
 116                                SectionKind::getMergeableConst16());
 117
 118   StaticCtorSection =
 119     getContext().getELFSection(".ctors", ELF::SHT_PROGBITS,
 120                                ELF::SHF_ALLOC |ELF::SHF_WRITE,
 121                                SectionKind::getDataRel());
 122
 123   StaticDtorSection =
 124     getContext().getELFSection(".dtors", ELF::SHT_PROGBITS,
 125                                ELF::SHF_ALLOC |ELF::SHF_WRITE,
 126                                SectionKind::getDataRel());
 127
 128   // Exception Handling Sections.
 129
 130   // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
 131   // it contains relocatable pointers.  In PIC mode, this is probably a big
 132   // runtime hit for C++ apps.  Either the contents of the LSDA need to be
 133   // adjusted or this should be a data section.
 134   LSDASection =
 135     getContext().getELFSection(".gcc_except_table", ELF::SHT_PROGBITS,
 136                                ELF::SHF_ALLOC,
 137                                SectionKind::getReadOnly());
 138   // Debug Info Sections.
 139   DwarfAbbrevSection =
 140     getContext().getELFSection(".debug_abbrev", ELF::SHT_PROGBITS, 0,
 141                                SectionKind::getMetadata());
 142   DwarfInfoSection =
 143     getContext().getELFSection(".debug_info", ELF::SHT_PROGBITS, 0,
 144                                SectionKind::getMetadata());
 145   DwarfLineSection =
 146     getContext().getELFSection(".debug_line", ELF::SHT_PROGBITS, 0,
 147                                SectionKind::getMetadata());
 148   DwarfFrameSection =
 149     getContext().getELFSection(".debug_frame", ELF::SHT_PROGBITS, 0,
 150                                SectionKind::getMetadata());
 151   DwarfPubNamesSection =
 152     getContext().getELFSection(".debug_pubnames", ELF::SHT_PROGBITS, 0,
 153                                SectionKind::getMetadata());
 154   DwarfPubTypesSection =
 155     getContext().getELFSection(".debug_pubtypes", ELF::SHT_PROGBITS, 0,
 156                                SectionKind::getMetadata());
 157   DwarfStrSection =
 158     getContext().getELFSection(".debug_str", ELF::SHT_PROGBITS, 0,
 159                                SectionKind::getMetadata());
 160   DwarfLocSection =
 161     getContext().getELFSection(".debug_loc", ELF::SHT_PROGBITS, 0,
 162                                SectionKind::getMetadata());
 163   DwarfARangesSection =
 164     getContext().getELFSection(".debug_aranges", ELF::SHT_PROGBITS, 0,
 165                                SectionKind::getMetadata());
 166   DwarfRangesSection =
 167     getContext().getELFSection(".debug_ranges", ELF::SHT_PROGBITS, 0,
 168                                SectionKind::getMetadata());
 169   DwarfMacroInfoSection =
 170     getContext().getELFSection(".debug_macinfo", ELF::SHT_PROGBITS, 0,
 171                                SectionKind::getMetadata());
 172 }
 173
 174 const MCSection *TargetLoweringObjectFileELF::getEHFrameSection() const {
 175   return getContext().getELFSection(".eh_frame", ELF::SHT_PROGBITS,
 176                                     ELF::SHF_ALLOC,
 177                                     SectionKind::getDataRel());
 178 }
 179
 180 MCSymbol *
 181 TargetLoweringObjectFileELF::getCFIPersonalitySymbol(const GlobalValue *GV,
 182                                                      Mangler *Mang,
 183                                                 MachineModuleInfo *MMI) const {
 184   unsigned Encoding = getPersonalityEncoding();
 185   switch (Encoding & 0x70) {
 186   default:
 187     report_fatal_error("We do not support this DWARF encoding yet!");
 188   case dwarf::DW_EH_PE_absptr:
 189     return  Mang->getSymbol(GV);
 190     break;
 191   case dwarf::DW_EH_PE_pcrel: {
 192     Twine FullName = StringRef("DW.ref.") + Mang->getSymbol(GV)->getName();
 193     return getContext().GetOrCreateSymbol(FullName);
 194     break;
 195   }
 196   }
 197 }
 198
 199 void TargetLoweringObjectFileELF::emitPersonalityValue(MCStreamer &Streamer,
 200                                                        const TargetMachine &TM,
 201                                                        const MCSymbol *Sym) const {
 202   Twine FullName = StringRef("DW.ref.") + Sym->getName();
 203   MCSymbol *Label = getContext().GetOrCreateSymbol(FullName);
 204   Streamer.EmitSymbolAttribute(Label, MCSA_Hidden);
 205   Streamer.EmitSymbolAttribute(Label, MCSA_Weak);
 206   Twine SectionName = StringRef(".data.") + Label->getName();
 207   SmallString<64> NameData;
 208   SectionName.toVector(NameData);
 209   unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP;
 210   const MCSection *Sec = getContext().getELFSection(NameData,
 211                                                     ELF::SHT_PROGBITS,
 212                                                     Flags,
 213                                                     SectionKind::getDataRel(),
 214                                                     0, Label->getName());
 215   Streamer.SwitchSection(Sec);
 216   Streamer.EmitValueToAlignment(8);
 217   Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject);
 218   const MCExpr *E = MCConstantExpr::Create(8, getContext());
 219   Streamer.EmitELFSize(Label, E);
 220   Streamer.EmitLabel(Label);
 221
 222   unsigned Size = TM.getTargetData()->getPointerSize();
 223   Streamer.EmitSymbolValue(Sym, Size);
 224 }
 225
 226 static SectionKind
 227 getELFKindForNamedSection(StringRef Name, SectionKind K) {
 228   // N.B.: The defaults used in here are no the same ones used in MC.
 229   // We follow gcc, MC follows gas. For example, given ".section .eh_frame",
 230   // both gas and MC will produce a section with no flags. Given
 231   // section(".eh_frame") gcc will produce
 232   // .section   .eh_frame,"a",@progbits
 233   if (Name.empty() || Name[0] != '.') return K;
 234
 235   // Some lame default implementation based on some magic section names.
 236   if (Name == ".bss" ||
 237       Name.startswith(".bss.") ||
 238       Name.startswith(".gnu.linkonce.b.") ||
 239       Name.startswith(".llvm.linkonce.b.") ||
 240       Name == ".sbss" ||
 241       Name.startswith(".sbss.") ||
 242       Name.startswith(".gnu.linkonce.sb.") ||
 243       Name.startswith(".llvm.linkonce.sb."))
 244     return SectionKind::getBSS();
 245
 246   if (Name == ".tdata" ||
 247       Name.startswith(".tdata.") ||
 248       Name.startswith(".gnu.linkonce.td.") ||
 249       Name.startswith(".llvm.linkonce.td."))
 250     return SectionKind::getThreadData();
 251
 252   if (Name == ".tbss" ||
 253       Name.startswith(".tbss.") ||
 254       Name.startswith(".gnu.linkonce.tb.") ||
 255       Name.startswith(".llvm.linkonce.tb."))
 256     return SectionKind::getThreadBSS();
 257
 258   if (Name == ".eh_frame")
 259     return SectionKind::getReadOnlyWithRel();
 260
 261   return K;
 262 }
 263
 264
 265 static unsigned getELFSectionType(StringRef Name, SectionKind K) {
 266
 267   if (Name == ".init_array")
 268     return ELF::SHT_INIT_ARRAY;
 269
 270   if (Name == ".fini_array")
 271     return ELF::SHT_FINI_ARRAY;
 272
 273   if (Name == ".preinit_array")
 274     return ELF::SHT_PREINIT_ARRAY;
 275
 276   if (K.isBSS() || K.isThreadBSS())
 277     return ELF::SHT_NOBITS;
 278
 279   return ELF::SHT_PROGBITS;
 280 }
 281
 282
 283 static unsigned
 284 getELFSectionFlags(SectionKind K) {
 285   unsigned Flags = 0;
 286
 287   if (!K.isMetadata())
 288     Flags |= ELF::SHF_ALLOC;
 289
 290   if (K.isText())
 291     Flags |= ELF::SHF_EXECINSTR;
 292
 293   if (K.isWriteable() && !K.isReadOnlyWithRel())
 294     Flags |= ELF::SHF_WRITE;
 295
 296   if (K.isThreadLocal())
 297     Flags |= ELF::SHF_TLS;
 298
 299   // K.isMergeableConst() is left out to honour PR4650
 300   if (K.isMergeableCString() || K.isMergeableConst4() ||
 301       K.isMergeableConst8() || K.isMergeableConst16())
 302     Flags |= ELF::SHF_MERGE;
 303
 304   if (K.isMergeableCString())
 305     Flags |= ELF::SHF_STRINGS;
 306
 307   return Flags;
 308 }
 309
 310
 311 const MCSection *TargetLoweringObjectFileELF::
 312 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 313                          Mangler *Mang, const TargetMachine &TM) const {
 314   StringRef SectionName = GV->getSection();
 315
 316   // Infer section flags from the section name if we can.
 317   Kind = getELFKindForNamedSection(SectionName, Kind);
 318
 319   return getContext().getELFSection(SectionName,
 320                                     getELFSectionType(SectionName, Kind),
 321                                     getELFSectionFlags(Kind), Kind);
 322 }
 323
 324 /// getSectionPrefixForGlobal - Return the section prefix name used by options
 325 /// FunctionsSections and DataSections.
 326 static const char *getSectionPrefixForGlobal(SectionKind Kind) {
 327   if (Kind.isText())                 return ".text.";
 328   if (Kind.isReadOnly())             return ".rodata.";
 329
 330   if (Kind.isThreadData())           return ".tdata.";
 331   if (Kind.isThreadBSS())            return ".tbss.";
 332
 333   if (Kind.isDataNoRel())            return ".data.";
 334   if (Kind.isDataRelLocal())         return ".data.rel.local.";
 335   if (Kind.isDataRel())              return ".data.rel.";
 336   if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local.";
 337
 338   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 339   return ".data.rel.ro.";
 340 }
 341
 342
 343 const MCSection *TargetLoweringObjectFileELF::
 344 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 345                        Mangler *Mang, const TargetMachine &TM) const {
 346   // If we have -ffunction-section or -fdata-section then we should emit the
 347   // global value to a uniqued section specifically for it.
 348   bool EmitUniquedSection;
 349   if (Kind.isText())
 350     EmitUniquedSection = TM.getFunctionSections();
 351   else
 352     EmitUniquedSection = TM.getDataSections();
 353
 354   // If this global is linkonce/weak and the target handles this by emitting it
 355   // into a 'uniqued' section name, create and return the section now.
 356   if ((GV->isWeakForLinker() || EmitUniquedSection) &&
 357       !Kind.isCommon() && !Kind.isBSS()) {
 358     const char *Prefix;
 359     Prefix = getSectionPrefixForGlobal(Kind);
 360
 361     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
 362     MCSymbol *Sym = Mang->getSymbol(GV);
 363     Name.append(Sym->getName().begin(), Sym->getName().end());
 364     StringRef Group = "";
 365     unsigned Flags = getELFSectionFlags(Kind);
 366     if (GV->isWeakForLinker()) {
 367       Group = Sym->getName();
 368       Flags |= ELF::SHF_GROUP;
 369     }
 370
 371     return getContext().getELFSection(Name.str(),
 372                                       getELFSectionType(Name.str(), Kind),
 373                                       Flags, Kind, 0, Group);
 374   }
 375
 376   if (Kind.isText()) return TextSection;
 377
 378   if (Kind.isMergeable1ByteCString() ||
 379       Kind.isMergeable2ByteCString() ||
 380       Kind.isMergeable4ByteCString()) {
 381
 382     // We also need alignment here.
 383     // FIXME: this is getting the alignment of the character, not the
 384     // alignment of the global!
 385     unsigned Align =
 386       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
 387
 388     const char *SizeSpec = ".rodata.str1.";
 389     if (Kind.isMergeable2ByteCString())
 390       SizeSpec = ".rodata.str2.";
 391     else if (Kind.isMergeable4ByteCString())
 392       SizeSpec = ".rodata.str4.";
 393     else
 394       assert(Kind.isMergeable1ByteCString() && "unknown string width");
 395
 396
 397     std::string Name = SizeSpec + utostr(Align);
 398     return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
 399                                       ELF::SHF_ALLOC |
 400                                       ELF::SHF_MERGE |
 401                                       ELF::SHF_STRINGS,
 402                                       Kind);
 403   }
 404
 405   if (Kind.isMergeableConst()) {
 406     if (Kind.isMergeableConst4() && MergeableConst4Section)
 407       return MergeableConst4Section;
 408     if (Kind.isMergeableConst8() && MergeableConst8Section)
 409       return MergeableConst8Section;
 410     if (Kind.isMergeableConst16() && MergeableConst16Section)
 411       return MergeableConst16Section;
 412     return ReadOnlySection;  // .const
 413   }
 414
 415   if (Kind.isReadOnly())             return ReadOnlySection;
 416
 417   if (Kind.isThreadData())           return TLSDataSection;
 418   if (Kind.isThreadBSS())            return TLSBSSSection;
 419
 420   // Note: we claim that common symbols are put in BSSSection, but they are
 421   // really emitted with the magic .comm directive, which creates a symbol table
 422   // entry but not a section.
 423   if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
 424
 425   if (Kind.isDataNoRel())            return DataSection;
 426   if (Kind.isDataRelLocal())         return DataRelLocalSection;
 427   if (Kind.isDataRel())              return DataRelSection;
 428   if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
 429
 430   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 431   return DataRelROSection;
 432 }
 433
 434 /// getSectionForConstant - Given a mergeable constant with the
 435 /// specified size and relocation information, return a section that it
 436 /// should be placed in.
 437 const MCSection *TargetLoweringObjectFileELF::
 438 getSectionForConstant(SectionKind Kind) const {
 439   if (Kind.isMergeableConst4() && MergeableConst4Section)
 440     return MergeableConst4Section;
 441   if (Kind.isMergeableConst8() && MergeableConst8Section)
 442     return MergeableConst8Section;
 443   if (Kind.isMergeableConst16() && MergeableConst16Section)
 444     return MergeableConst16Section;
 445   if (Kind.isReadOnly())
 446     return ReadOnlySection;
 447
 448   if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
 449   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 450   return DataRelROSection;
 451 }
 452
 453 const MCExpr *TargetLoweringObjectFileELF::
 454 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
 455                                MachineModuleInfo *MMI,
 456                                unsigned Encoding, MCStreamer &Streamer) const {
 457
 458   if (Encoding & dwarf::DW_EH_PE_indirect) {
 459     MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
 460
 461     SmallString<128> Name;
 462     Mang->getNameWithPrefix(Name, GV, true);
 463     Name += ".DW.stub";
 464
 465     // Add information about the stub reference to ELFMMI so that the stub
 466     // gets emitted by the asmprinter.
 467     MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
 468     MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
 469     if (StubSym.getPointer() == 0) {
 470       MCSymbol *Sym = Mang->getSymbol(GV);
 471       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
 472     }
 473
 474     return TargetLoweringObjectFile::
 475       getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
 476   }
 477
 478   return TargetLoweringObjectFile::
 479     getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
 480 }
 481
 482 //===----------------------------------------------------------------------===//
 483 //                                 MachO
 484 //===----------------------------------------------------------------------===//
 485
 486 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
 487                                                const TargetMachine &TM) {
 488   IsFunctionEHFrameSymbolPrivate = false;
 489   SupportsWeakOmittedEHFrame = false;
 490
 491   // .comm doesn't support alignment before Leopard.
 492   Triple T(((LLVMTargetMachine&)TM).getTargetTriple());
 493   if (T.isMacOSX() && T.isMacOSXVersionLT(10, 5))
 494     CommDirectiveSupportsAlignment = false;
 495
 496   TargetLoweringObjectFile::Initialize(Ctx, TM);
 497
 498   TextSection // .text
 499     = getContext().getMachOSection("__TEXT", "__text",
 500                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 501                                    SectionKind::getText());
 502   DataSection // .data
 503     = getContext().getMachOSection("__DATA", "__data", 0,
 504                                    SectionKind::getDataRel());
 505
 506   TLSDataSection // .tdata
 507     = getContext().getMachOSection("__DATA", "__thread_data",
 508                                    MCSectionMachO::S_THREAD_LOCAL_REGULAR,
 509                                    SectionKind::getDataRel());
 510   TLSBSSSection // .tbss
 511     = getContext().getMachOSection("__DATA", "__thread_bss",
 512                                    MCSectionMachO::S_THREAD_LOCAL_ZEROFILL,
 513                                    SectionKind::getThreadBSS());
 514
 515   // TODO: Verify datarel below.
 516   TLSTLVSection // .tlv
 517     = getContext().getMachOSection("__DATA", "__thread_vars",
 518                                    MCSectionMachO::S_THREAD_LOCAL_VARIABLES,
 519                                    SectionKind::getDataRel());
 520
 521   TLSThreadInitSection
 522     = getContext().getMachOSection("__DATA", "__thread_init",
 523                           MCSectionMachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
 524                           SectionKind::getDataRel());
 525
 526   CStringSection // .cstring
 527     = getContext().getMachOSection("__TEXT", "__cstring",
 528                                    MCSectionMachO::S_CSTRING_LITERALS,
 529                                    SectionKind::getMergeable1ByteCString());
 530   UStringSection
 531     = getContext().getMachOSection("__TEXT","__ustring", 0,
 532                                    SectionKind::getMergeable2ByteCString());
 533   FourByteConstantSection // .literal4
 534     = getContext().getMachOSection("__TEXT", "__literal4",
 535                                    MCSectionMachO::S_4BYTE_LITERALS,
 536                                    SectionKind::getMergeableConst4());
 537   EightByteConstantSection // .literal8
 538     = getContext().getMachOSection("__TEXT", "__literal8",
 539                                    MCSectionMachO::S_8BYTE_LITERALS,
 540                                    SectionKind::getMergeableConst8());
 541
 542   // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
 543   // to using it in -static mode.
 544   SixteenByteConstantSection = 0;
 545   if (TM.getRelocationModel() != Reloc::Static &&
 546       TM.getTargetData()->getPointerSize() == 32)
 547     SixteenByteConstantSection =   // .literal16
 548       getContext().getMachOSection("__TEXT", "__literal16",
 549                                    MCSectionMachO::S_16BYTE_LITERALS,
 550                                    SectionKind::getMergeableConst16());
 551
 552   ReadOnlySection  // .const
 553     = getContext().getMachOSection("__TEXT", "__const", 0,
 554                                    SectionKind::getReadOnly());
 555
 556   TextCoalSection
 557     = getContext().getMachOSection("__TEXT", "__textcoal_nt",
 558                                    MCSectionMachO::S_COALESCED |
 559                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 560                                    SectionKind::getText());
 561   ConstTextCoalSection
 562     = getContext().getMachOSection("__TEXT", "__const_coal",
 563                                    MCSectionMachO::S_COALESCED,
 564                                    SectionKind::getReadOnly());
 565   ConstDataSection  // .const_data
 566     = getContext().getMachOSection("__DATA", "__const", 0,
 567                                    SectionKind::getReadOnlyWithRel());
 568   DataCoalSection
 569     = getContext().getMachOSection("__DATA","__datacoal_nt",
 570                                    MCSectionMachO::S_COALESCED,
 571                                    SectionKind::getDataRel());
 572   DataCommonSection
 573     = getContext().getMachOSection("__DATA","__common",
 574                                    MCSectionMachO::S_ZEROFILL,
 575                                    SectionKind::getBSS());
 576   DataBSSSection
 577     = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
 578                                    SectionKind::getBSS());
 579
 580
 581   LazySymbolPointerSection
 582     = getContext().getMachOSection("__DATA", "__la_symbol_ptr",
 583                                    MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
 584                                    SectionKind::getMetadata());
 585   NonLazySymbolPointerSection
 586     = getContext().getMachOSection("__DATA", "__nl_symbol_ptr",
 587                                    MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
 588                                    SectionKind::getMetadata());
 589
 590   if (TM.getRelocationModel() == Reloc::Static) {
 591     StaticCtorSection
 592       = getContext().getMachOSection("__TEXT", "__constructor", 0,
 593                                      SectionKind::getDataRel());
 594     StaticDtorSection
 595       = getContext().getMachOSection("__TEXT", "__destructor", 0,
 596                                      SectionKind::getDataRel());
 597   } else {
 598     StaticCtorSection
 599       = getContext().getMachOSection("__DATA", "__mod_init_func",
 600                                      MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
 601                                      SectionKind::getDataRel());
 602     StaticDtorSection
 603       = getContext().getMachOSection("__DATA", "__mod_term_func",
 604                                      MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
 605                                      SectionKind::getDataRel());
 606   }
 607
 608   // Exception Handling.
 609   LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0,
 610                                              SectionKind::getReadOnlyWithRel());
 611   // Debug Information.
 612   DwarfAbbrevSection =
 613     getContext().getMachOSection("__DWARF", "__debug_abbrev",
 614                                  MCSectionMachO::S_ATTR_DEBUG,
 615                                  SectionKind::getMetadata());
 616   DwarfInfoSection =
 617     getContext().getMachOSection("__DWARF", "__debug_info",
 618                                  MCSectionMachO::S_ATTR_DEBUG,
 619                                  SectionKind::getMetadata());
 620   DwarfLineSection =
 621     getContext().getMachOSection("__DWARF", "__debug_line",
 622                                  MCSectionMachO::S_ATTR_DEBUG,
 623                                  SectionKind::getMetadata());
 624   DwarfFrameSection =
 625     getContext().getMachOSection("__DWARF", "__debug_frame",
 626                                  MCSectionMachO::S_ATTR_DEBUG,
 627                                  SectionKind::getMetadata());
 628   DwarfPubNamesSection =
 629     getContext().getMachOSection("__DWARF", "__debug_pubnames",
 630                                  MCSectionMachO::S_ATTR_DEBUG,
 631                                  SectionKind::getMetadata());
 632   DwarfPubTypesSection =
 633     getContext().getMachOSection("__DWARF", "__debug_pubtypes",
 634                                  MCSectionMachO::S_ATTR_DEBUG,
 635                                  SectionKind::getMetadata());
 636   DwarfStrSection =
 637     getContext().getMachOSection("__DWARF", "__debug_str",
 638                                  MCSectionMachO::S_ATTR_DEBUG,
 639                                  SectionKind::getMetadata());
 640   DwarfLocSection =
 641     getContext().getMachOSection("__DWARF", "__debug_loc",
 642                                  MCSectionMachO::S_ATTR_DEBUG,
 643                                  SectionKind::getMetadata());
 644   DwarfARangesSection =
 645     getContext().getMachOSection("__DWARF", "__debug_aranges",
 646                                  MCSectionMachO::S_ATTR_DEBUG,
 647                                  SectionKind::getMetadata());
 648   DwarfRangesSection =
 649     getContext().getMachOSection("__DWARF", "__debug_ranges",
 650                                  MCSectionMachO::S_ATTR_DEBUG,
 651                                  SectionKind::getMetadata());
 652   DwarfMacroInfoSection =
 653     getContext().getMachOSection("__DWARF", "__debug_macinfo",
 654                                  MCSectionMachO::S_ATTR_DEBUG,
 655                                  SectionKind::getMetadata());
 656   DwarfDebugInlineSection =
 657     getContext().getMachOSection("__DWARF", "__debug_inlined",
 658                                  MCSectionMachO::S_ATTR_DEBUG,
 659                                  SectionKind::getMetadata());
 660
 661   TLSExtraDataSection = TLSTLVSection;
 662 }
 663
 664 const MCSection *TargetLoweringObjectFileMachO::getEHFrameSection() const {
 665   return getContext().getMachOSection("__TEXT", "__eh_frame",
 666                                       MCSectionMachO::S_COALESCED |
 667                                       MCSectionMachO::S_ATTR_NO_TOC |
 668                                       MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
 669                                       MCSectionMachO::S_ATTR_LIVE_SUPPORT,
 670                                       SectionKind::getReadOnly());
 671 }
 672
 673 const MCSection *TargetLoweringObjectFileMachO::
 674 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 675                          Mangler *Mang, const TargetMachine &TM) const {
 676   // Parse the section specifier and create it if valid.
 677   StringRef Segment, Section;
 678   unsigned TAA = 0, StubSize = 0;
 679   bool TAAParsed;
 680   std::string ErrorCode =
 681     MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
 682                                           TAA, TAAParsed, StubSize);
 683   if (!ErrorCode.empty()) {
 684     // If invalid, report the error with report_fatal_error.
 685     report_fatal_error("Global variable '" + GV->getNameStr() +
 686                       "' has an invalid section specifier '" + GV->getSection()+
 687                       "': " + ErrorCode + ".");
 688     // Fall back to dropping it into the data section.
 689     return DataSection;
 690   }
 691
 692   // Get the section.
 693   const MCSectionMachO *S =
 694     getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
 695
 696   // If TAA wasn't set by ParseSectionSpecifier() above,
 697   // use the value returned by getMachOSection() as a default.
 698   if (!TAAParsed)
 699     TAA = S->getTypeAndAttributes();
 700
 701   // Okay, now that we got the section, verify that the TAA & StubSize agree.
 702   // If the user declared multiple globals with different section flags, we need
 703   // to reject it here.
 704   if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
 705     // If invalid, report the error with report_fatal_error.
 706     report_fatal_error("Global variable '" + GV->getNameStr() +
 707                       "' section type or attributes does not match previous"
 708                       " section specifier");
 709   }
 710
 711   return S;
 712 }
 713
 714 const MCSection *TargetLoweringObjectFileMachO::
 715 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 716                        Mangler *Mang, const TargetMachine &TM) const {
 717
 718   // Handle thread local data.
 719   if (Kind.isThreadBSS()) return TLSBSSSection;
 720   if (Kind.isThreadData()) return TLSDataSection;
 721
 722   if (Kind.isText())
 723     return GV->isWeakForLinker() ? TextCoalSection : TextSection;
 724
 725   // If this is weak/linkonce, put this in a coalescable section, either in text
 726   // or data depending on if it is writable.
 727   if (GV->isWeakForLinker()) {
 728     if (Kind.isReadOnly())
 729       return ConstTextCoalSection;
 730     return DataCoalSection;
 731   }
 732
 733   // FIXME: Alignment check should be handled by section classifier.
 734   if (Kind.isMergeable1ByteCString() &&
 735       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
 736     return CStringSection;
 737
 738   // Do not put 16-bit arrays in the UString section if they have an
 739   // externally visible label, this runs into issues with certain linker
 740   // versions.
 741   if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
 742       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
 743     return UStringSection;
 744
 745   if (Kind.isMergeableConst()) {
 746     if (Kind.isMergeableConst4())
 747       return FourByteConstantSection;
 748     if (Kind.isMergeableConst8())
 749       return EightByteConstantSection;
 750     if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 751       return SixteenByteConstantSection;
 752   }
 753
 754   // Otherwise, if it is readonly, but not something we can specially optimize,
 755   // just drop it in .const.
 756   if (Kind.isReadOnly())
 757     return ReadOnlySection;
 758
 759   // If this is marked const, put it into a const section.  But if the dynamic
 760   // linker needs to write to it, put it in the data segment.
 761   if (Kind.isReadOnlyWithRel())
 762     return ConstDataSection;
 763
 764   // Put zero initialized globals with strong external linkage in the
 765   // DATA, __common section with the .zerofill directive.
 766   if (Kind.isBSSExtern())
 767     return DataCommonSection;
 768
 769   // Put zero initialized globals with local linkage in __DATA,__bss directive
 770   // with the .zerofill directive (aka .lcomm).
 771   if (Kind.isBSSLocal())
 772     return DataBSSSection;
 773
 774   // Otherwise, just drop the variable in the normal data section.
 775   return DataSection;
 776 }
 777
 778 const MCSection *
 779 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
 780   // If this constant requires a relocation, we have to put it in the data
 781   // segment, not in the text segment.
 782   if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
 783     return ConstDataSection;
 784
 785   if (Kind.isMergeableConst4())
 786     return FourByteConstantSection;
 787   if (Kind.isMergeableConst8())
 788     return EightByteConstantSection;
 789   if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 790     return SixteenByteConstantSection;
 791   return ReadOnlySection;  // .const
 792 }
 793
 794 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
 795 /// not to emit the UsedDirective for some symbols in llvm.used.
 796 // FIXME: REMOVE this (rdar://7071300)
 797 bool TargetLoweringObjectFileMachO::
 798 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
 799   /// On Darwin, internally linked data beginning with "L" or "l" does not have
 800   /// the directive emitted (this occurs in ObjC metadata).
 801   if (!GV) return false;
 802
 803   // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
 804   if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
 805     // FIXME: ObjC metadata is currently emitted as internal symbols that have
 806     // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
 807     // this horrible hack can go away.
 808     MCSymbol *Sym = Mang->getSymbol(GV);
 809     if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
 810       return false;
 811   }
 812
 813   return true;
 814 }
 815
 816 const MCExpr *TargetLoweringObjectFileMachO::
 817 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
 818                                MachineModuleInfo *MMI, unsigned Encoding,
 819                                MCStreamer &Streamer) const {
 820   // The mach-o version of this method defaults to returning a stub reference.
 821
 822   if (Encoding & DW_EH_PE_indirect) {
 823     MachineModuleInfoMachO &MachOMMI =
 824       MMI->getObjFileInfo<MachineModuleInfoMachO>();
 825
 826     SmallString<128> Name;
 827     Mang->getNameWithPrefix(Name, GV, true);
 828     Name += "$non_lazy_ptr";
 829
 830     // Add information about the stub reference to MachOMMI so that the stub
 831     // gets emitted by the asmprinter.
 832     MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
 833     MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
 834     if (StubSym.getPointer() == 0) {
 835       MCSymbol *Sym = Mang->getSymbol(GV);
 836       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
 837     }
 838
 839     return TargetLoweringObjectFile::
 840       getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
 841   }
 842
 843   return TargetLoweringObjectFile::
 844     getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
 845 }
 846
 847 MCSymbol *TargetLoweringObjectFileMachO::
 848 getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang,
 849                         MachineModuleInfo *MMI) const {
 850   // The mach-o version of this method defaults to returning a stub reference.
 851   MachineModuleInfoMachO &MachOMMI =
 852     MMI->getObjFileInfo<MachineModuleInfoMachO>();
 853
 854   SmallString<128> Name;
 855   Mang->getNameWithPrefix(Name, GV, true);
 856   Name += "$non_lazy_ptr";
 857
 858   // Add information about the stub reference to MachOMMI so that the stub
 859   // gets emitted by the asmprinter.
 860   MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
 861   MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
 862   if (StubSym.getPointer() == 0) {
 863     MCSymbol *Sym = Mang->getSymbol(GV);
 864     StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
 865   }
 866
 867   return SSym;
 868 }
 869
 870 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const {
 871   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
 872 }
 873
 874 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const {
 875   return DW_EH_PE_pcrel;
 876 }
 877
 878 unsigned TargetLoweringObjectFileMachO::getFDEEncoding(bool CFI) const {
 879   return DW_EH_PE_pcrel;
 880 }
 881
 882 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const {
 883   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
 884 }
 885
 886 //===----------------------------------------------------------------------===//
 887 //                                  COFF
 888 //===----------------------------------------------------------------------===//
 889
 890 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
 891                                               const TargetMachine &TM) {
 892   TargetLoweringObjectFile::Initialize(Ctx, TM);
 893   TextSection =
 894     getContext().getCOFFSection(".text",
 895                                 COFF::IMAGE_SCN_CNT_CODE |
 896                                 COFF::IMAGE_SCN_MEM_EXECUTE |
 897                                 COFF::IMAGE_SCN_MEM_READ,
 898                                 SectionKind::getText());
 899   DataSection =
 900     getContext().getCOFFSection(".data",
 901                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 902                                 COFF::IMAGE_SCN_MEM_READ |
 903                                 COFF::IMAGE_SCN_MEM_WRITE,
 904                                 SectionKind::getDataRel());
 905   ReadOnlySection =
 906     getContext().getCOFFSection(".rdata",
 907                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 908                                 COFF::IMAGE_SCN_MEM_READ,
 909                                 SectionKind::getReadOnly());
 910   StaticCtorSection =
 911     getContext().getCOFFSection(".ctors",
 912                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 913                                 COFF::IMAGE_SCN_MEM_READ |
 914                                 COFF::IMAGE_SCN_MEM_WRITE,
 915                                 SectionKind::getDataRel());
 916   StaticDtorSection =
 917     getContext().getCOFFSection(".dtors",
 918                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 919                                 COFF::IMAGE_SCN_MEM_READ |
 920                                 COFF::IMAGE_SCN_MEM_WRITE,
 921                                 SectionKind::getDataRel());
 922
 923   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
 924   // though it contains relocatable pointers.  In PIC mode, this is probably a
 925   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
 926   // adjusted or this should be a data section.
 927   LSDASection =
 928     getContext().getCOFFSection(".gcc_except_table",
 929                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 930                                 COFF::IMAGE_SCN_MEM_READ,
 931                                 SectionKind::getReadOnly());
 932   // Debug info.
 933   DwarfAbbrevSection =
 934     getContext().getCOFFSection(".debug_abbrev",
 935                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 936                                 COFF::IMAGE_SCN_MEM_READ,
 937                                 SectionKind::getMetadata());
 938   DwarfInfoSection =
 939     getContext().getCOFFSection(".debug_info",
 940                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 941                                 COFF::IMAGE_SCN_MEM_READ,
 942                                 SectionKind::getMetadata());
 943   DwarfLineSection =
 944     getContext().getCOFFSection(".debug_line",
 945                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 946                                 COFF::IMAGE_SCN_MEM_READ,
 947                                 SectionKind::getMetadata());
 948   DwarfFrameSection =
 949     getContext().getCOFFSection(".debug_frame",
 950                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 951                                 COFF::IMAGE_SCN_MEM_READ,
 952                                 SectionKind::getMetadata());
 953   DwarfPubNamesSection =
 954     getContext().getCOFFSection(".debug_pubnames",
 955                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 956                                 COFF::IMAGE_SCN_MEM_READ,
 957                                 SectionKind::getMetadata());
 958   DwarfPubTypesSection =
 959     getContext().getCOFFSection(".debug_pubtypes",
 960                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 961                                 COFF::IMAGE_SCN_MEM_READ,
 962                                 SectionKind::getMetadata());
 963   DwarfStrSection =
 964     getContext().getCOFFSection(".debug_str",
 965                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 966                                 COFF::IMAGE_SCN_MEM_READ,
 967                                 SectionKind::getMetadata());
 968   DwarfLocSection =
 969     getContext().getCOFFSection(".debug_loc",
 970                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 971                                 COFF::IMAGE_SCN_MEM_READ,
 972                                 SectionKind::getMetadata());
 973   DwarfARangesSection =
 974     getContext().getCOFFSection(".debug_aranges",
 975                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 976                                 COFF::IMAGE_SCN_MEM_READ,
 977                                 SectionKind::getMetadata());
 978   DwarfRangesSection =
 979     getContext().getCOFFSection(".debug_ranges",
 980                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 981                                 COFF::IMAGE_SCN_MEM_READ,
 982                                 SectionKind::getMetadata());
 983   DwarfMacroInfoSection =
 984     getContext().getCOFFSection(".debug_macinfo",
 985                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 986                                 COFF::IMAGE_SCN_MEM_READ,
 987                                 SectionKind::getMetadata());
 988
 989   DrectveSection =
 990     getContext().getCOFFSection(".drectve",
 991                                 COFF::IMAGE_SCN_LNK_INFO,
 992                                 SectionKind::getMetadata());
 993
 994   PDataSection =
 995     getContext().getCOFFSection(".pdata",
 996                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 997                                 COFF::IMAGE_SCN_MEM_READ |
 998                                 COFF::IMAGE_SCN_MEM_WRITE,
 999                                 SectionKind::getDataRel());
1000
1001   XDataSection =
1002     getContext().getCOFFSection(".xdata",
1003                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1004                                 COFF::IMAGE_SCN_MEM_READ |
1005                                 COFF::IMAGE_SCN_MEM_WRITE,
1006                                 SectionKind::getDataRel());
1007 }
1008
1009 const MCSection *TargetLoweringObjectFileCOFF::getEHFrameSection() const {
1010   return getContext().getCOFFSection(".eh_frame",
1011                                      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1012                                      COFF::IMAGE_SCN_MEM_READ |
1013                                      COFF::IMAGE_SCN_MEM_WRITE,
1014                                      SectionKind::getDataRel());
1015 }
1016
1017 const MCSection *TargetLoweringObjectFileCOFF::getWin64EHFuncTableSection(
1018                                                        StringRef suffix) const {
1019   if (suffix == "")
1020     return PDataSection;
1021   return getContext().getCOFFSection((".pdata"+suffix).str(),
1022                                      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1023                                      COFF::IMAGE_SCN_MEM_READ |
1024                                      COFF::IMAGE_SCN_MEM_WRITE,
1025                                      SectionKind::getDataRel());
1026 }
1027
1028 const MCSection *TargetLoweringObjectFileCOFF::getWin64EHTableSection(
1029                                                        StringRef suffix) const {
1030   if (suffix == "")
1031     return XDataSection;
1032   return getContext().getCOFFSection((".xdata"+suffix).str(),
1033                                      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1034                                      COFF::IMAGE_SCN_MEM_READ |
1035                                      COFF::IMAGE_SCN_MEM_WRITE,
1036                                      SectionKind::getDataRel());
1037 }
1038
1039
1040 static unsigned
1041 getCOFFSectionFlags(SectionKind K) {
1042   unsigned Flags = 0;
1043
1044   if (K.isMetadata())
1045     Flags |=
1046       COFF::IMAGE_SCN_MEM_DISCARDABLE;
1047   else if (K.isText())
1048     Flags |=
1049       COFF::IMAGE_SCN_MEM_EXECUTE |
1050       COFF::IMAGE_SCN_MEM_READ |
1051       COFF::IMAGE_SCN_CNT_CODE;
1052   else if (K.isBSS ())
1053     Flags |=
1054       COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
1055       COFF::IMAGE_SCN_MEM_READ |
1056       COFF::IMAGE_SCN_MEM_WRITE;
1057   else if (K.isReadOnly())
1058     Flags |=
1059       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1060       COFF::IMAGE_SCN_MEM_READ;
1061   else if (K.isWriteable())
1062     Flags |=
1063       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
1064       COFF::IMAGE_SCN_MEM_READ |
1065       COFF::IMAGE_SCN_MEM_WRITE;
1066
1067   return Flags;
1068 }
1069
1070 const MCSection *TargetLoweringObjectFileCOFF::
1071 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
1072                          Mangler *Mang, const TargetMachine &TM) const {
1073   return getContext().getCOFFSection(GV->getSection(),
1074                                      getCOFFSectionFlags(Kind),
1075                                      Kind);
1076 }
1077
1078 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
1079   if (Kind.isText())
1080     return ".text$";
1081   if (Kind.isBSS ())
1082     return ".bss$";
1083   if (Kind.isWriteable())
1084     return ".data$";
1085   return ".rdata$";
1086 }
1087
1088
1089 const MCSection *TargetLoweringObjectFileCOFF::
1090 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
1091                        Mangler *Mang, const TargetMachine &TM) const {
1092   assert(!Kind.isThreadLocal() && "Doesn't support TLS");
1093
1094   // If this global is linkonce/weak and the target handles this by emitting it
1095   // into a 'uniqued' section name, create and return the section now.
1096   if (GV->isWeakForLinker()) {
1097     const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
1098     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
1099     MCSymbol *Sym = Mang->getSymbol(GV);
1100     Name.append(Sym->getName().begin() + 1, Sym->getName().end());
1101
1102     unsigned Characteristics = getCOFFSectionFlags(Kind);
1103
1104     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
1105
1106     return getContext().getCOFFSection(Name.str(), Characteristics,
1107                           COFF::IMAGE_COMDAT_SELECT_ANY, Kind);
1108   }
1109
1110   if (Kind.isText())
1111     return getTextSection();
1112
1113   return getDataSection();
1114 }
1115