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