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