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/MCSymbol.h"
  27 #include "llvm/Target/Mangler.h"
  28 #include "llvm/Target/TargetData.h"
  29 #include "llvm/Target/TargetMachine.h"
  30 #include "llvm/Target/TargetOptions.h"
  31 #include "llvm/Support/Dwarf.h"
  32 #include "llvm/Support/ELF.h"
  33 #include "llvm/Support/ErrorHandling.h"
  34 #include "llvm/Support/raw_ostream.h"
  35 #include "llvm/ADT/SmallString.h"
  36 #include "llvm/ADT/StringExtras.h"
  37 #include "llvm/ADT/Triple.h"
  38 using namespace llvm;
  39 using namespace dwarf;
  40
  41 //===----------------------------------------------------------------------===//
  42 //                                  ELF
  43 //===----------------------------------------------------------------------===//
  44
  45 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
  46                                              const TargetMachine &TM) {
  47   TargetLoweringObjectFile::Initialize(Ctx, TM);
  48
  49   BSSSection =
  50     getContext().getELFSection(".bss", ELF::SHT_NOBITS,
  51                                ELF::SHF_WRITE |ELF::SHF_ALLOC,
  52                                SectionKind::getBSS());
  53
  54   TextSection =
  55     getContext().getELFSection(".text", ELF::SHT_PROGBITS,
  56                                ELF::SHF_EXECINSTR |
  57                                ELF::SHF_ALLOC,
  58                                SectionKind::getText());
  59
  60   DataSection =
  61     getContext().getELFSection(".data", ELF::SHT_PROGBITS,
  62                                ELF::SHF_WRITE |ELF::SHF_ALLOC,
  63                                SectionKind::getDataRel());
  64
  65   ReadOnlySection =
  66     getContext().getELFSection(".rodata", ELF::SHT_PROGBITS,
  67                                ELF::SHF_ALLOC,
  68                                SectionKind::getReadOnly());
  69
  70   TLSDataSection =
  71     getContext().getELFSection(".tdata", ELF::SHT_PROGBITS,
  72                                ELF::SHF_ALLOC | ELF::SHF_TLS |
  73                                ELF::SHF_WRITE,
  74                                SectionKind::getThreadData());
  75
  76   TLSBSSSection =
  77     getContext().getELFSection(".tbss", ELF::SHT_NOBITS,
  78                                ELF::SHF_ALLOC | ELF::SHF_TLS |
  79                                ELF::SHF_WRITE,
  80                                SectionKind::getThreadBSS());
  81
  82   DataRelSection =
  83     getContext().getELFSection(".data.rel", ELF::SHT_PROGBITS,
  84                                ELF::SHF_ALLOC |ELF::SHF_WRITE,
  85                                SectionKind::getDataRel());
  86
  87   DataRelLocalSection =
  88     getContext().getELFSection(".data.rel.local", ELF::SHT_PROGBITS,
  89                                ELF::SHF_ALLOC |ELF::SHF_WRITE,
  90                                SectionKind::getDataRelLocal());
  91
  92   DataRelROSection =
  93     getContext().getELFSection(".data.rel.ro", ELF::SHT_PROGBITS,
  94                                ELF::SHF_ALLOC |ELF::SHF_WRITE,
  95                                SectionKind::getReadOnlyWithRel());
  96
  97   DataRelROLocalSection =
  98     getContext().getELFSection(".data.rel.ro.local", ELF::SHT_PROGBITS,
  99                                ELF::SHF_ALLOC |ELF::SHF_WRITE,
 100                                SectionKind::getReadOnlyWithRelLocal());
 101
 102   MergeableConst4Section =
 103     getContext().getELFSection(".rodata.cst4", ELF::SHT_PROGBITS,
 104                                ELF::SHF_ALLOC |ELF::SHF_MERGE,
 105                                SectionKind::getMergeableConst4());
 106
 107   MergeableConst8Section =
 108     getContext().getELFSection(".rodata.cst8", ELF::SHT_PROGBITS,
 109                                ELF::SHF_ALLOC |ELF::SHF_MERGE,
 110                                SectionKind::getMergeableConst8());
 111
 112   MergeableConst16Section =
 113     getContext().getELFSection(".rodata.cst16", ELF::SHT_PROGBITS,
 114                                ELF::SHF_ALLOC |ELF::SHF_MERGE,
 115                                SectionKind::getMergeableConst16());
 116
 117   StaticCtorSection =
 118     getContext().getELFSection(".ctors", ELF::SHT_PROGBITS,
 119                                ELF::SHF_ALLOC |ELF::SHF_WRITE,
 120                                SectionKind::getDataRel());
 121
 122   StaticDtorSection =
 123     getContext().getELFSection(".dtors", ELF::SHT_PROGBITS,
 124                                ELF::SHF_ALLOC |ELF::SHF_WRITE,
 125                                SectionKind::getDataRel());
 126
 127   // Exception Handling Sections.
 128
 129   // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
 130   // it contains relocatable pointers.  In PIC mode, this is probably a big
 131   // runtime hit for C++ apps.  Either the contents of the LSDA need to be
 132   // adjusted or this should be a data section.
 133   LSDASection =
 134     getContext().getELFSection(".gcc_except_table", ELF::SHT_PROGBITS,
 135                                ELF::SHF_ALLOC,
 136                                SectionKind::getReadOnly());
 137   // Debug Info Sections.
 138   DwarfAbbrevSection =
 139     getContext().getELFSection(".debug_abbrev", ELF::SHT_PROGBITS, 0,
 140                                SectionKind::getMetadata());
 141   DwarfInfoSection =
 142     getContext().getELFSection(".debug_info", ELF::SHT_PROGBITS, 0,
 143                                SectionKind::getMetadata());
 144   DwarfLineSection =
 145     getContext().getELFSection(".debug_line", ELF::SHT_PROGBITS, 0,
 146                                SectionKind::getMetadata());
 147   DwarfFrameSection =
 148     getContext().getELFSection(".debug_frame", ELF::SHT_PROGBITS, 0,
 149                                SectionKind::getMetadata());
 150   DwarfPubNamesSection =
 151     getContext().getELFSection(".debug_pubnames", ELF::SHT_PROGBITS, 0,
 152                                SectionKind::getMetadata());
 153   DwarfPubTypesSection =
 154     getContext().getELFSection(".debug_pubtypes", ELF::SHT_PROGBITS, 0,
 155                                SectionKind::getMetadata());
 156   DwarfStrSection =
 157     getContext().getELFSection(".debug_str", ELF::SHT_PROGBITS, 0,
 158                                SectionKind::getMetadata());
 159   DwarfLocSection =
 160     getContext().getELFSection(".debug_loc", ELF::SHT_PROGBITS, 0,
 161                                SectionKind::getMetadata());
 162   DwarfARangesSection =
 163     getContext().getELFSection(".debug_aranges", ELF::SHT_PROGBITS, 0,
 164                                SectionKind::getMetadata());
 165   DwarfRangesSection =
 166     getContext().getELFSection(".debug_ranges", ELF::SHT_PROGBITS, 0,
 167                                SectionKind::getMetadata());
 168   DwarfMacroInfoSection =
 169     getContext().getELFSection(".debug_macinfo", ELF::SHT_PROGBITS, 0,
 170                                SectionKind::getMetadata());
 171 }
 172
 173 const MCSection *TargetLoweringObjectFileELF::getEHFrameSection() const {
 174   return getContext().getELFSection(".eh_frame", ELF::SHT_PROGBITS,
 175                                     ELF::SHF_ALLOC,
 176                                     SectionKind::getDataRel());
 177 }
 178
 179 static SectionKind
 180 getELFKindForNamedSection(StringRef Name, SectionKind K) {
 181   if (Name.empty() || Name[0] != '.') return K;
 182
 183   // Some lame default implementation based on some magic section names.
 184   if (Name == ".bss" ||
 185       Name.startswith(".bss.") ||
 186       Name.startswith(".gnu.linkonce.b.") ||
 187       Name.startswith(".llvm.linkonce.b.") ||
 188       Name == ".sbss" ||
 189       Name.startswith(".sbss.") ||
 190       Name.startswith(".gnu.linkonce.sb.") ||
 191       Name.startswith(".llvm.linkonce.sb."))
 192     return SectionKind::getBSS();
 193
 194   if (Name == ".tdata" ||
 195       Name.startswith(".tdata.") ||
 196       Name.startswith(".gnu.linkonce.td.") ||
 197       Name.startswith(".llvm.linkonce.td."))
 198     return SectionKind::getThreadData();
 199
 200   if (Name == ".tbss" ||
 201       Name.startswith(".tbss.") ||
 202       Name.startswith(".gnu.linkonce.tb.") ||
 203       Name.startswith(".llvm.linkonce.tb."))
 204     return SectionKind::getThreadBSS();
 205
 206   return K;
 207 }
 208
 209
 210 static unsigned getELFSectionType(StringRef Name, SectionKind K) {
 211
 212   if (Name == ".init_array")
 213     return ELF::SHT_INIT_ARRAY;
 214
 215   if (Name == ".fini_array")
 216     return ELF::SHT_FINI_ARRAY;
 217
 218   if (Name == ".preinit_array")
 219     return ELF::SHT_PREINIT_ARRAY;
 220
 221   if (K.isBSS() || K.isThreadBSS())
 222     return ELF::SHT_NOBITS;
 223
 224   return ELF::SHT_PROGBITS;
 225 }
 226
 227
 228 static unsigned
 229 getELFSectionFlags(SectionKind K) {
 230   unsigned Flags = 0;
 231
 232   if (!K.isMetadata())
 233     Flags |= ELF::SHF_ALLOC;
 234
 235   if (K.isText())
 236     Flags |= ELF::SHF_EXECINSTR;
 237
 238   if (K.isWriteable())
 239     Flags |= ELF::SHF_WRITE;
 240
 241   if (K.isThreadLocal())
 242     Flags |= ELF::SHF_TLS;
 243
 244   // K.isMergeableConst() is left out to honour PR4650
 245   if (K.isMergeableCString() || K.isMergeableConst4() ||
 246       K.isMergeableConst8() || K.isMergeableConst16())
 247     Flags |= ELF::SHF_MERGE;
 248
 249   if (K.isMergeableCString())
 250     Flags |= ELF::SHF_STRINGS;
 251
 252   return Flags;
 253 }
 254
 255
 256 const MCSection *TargetLoweringObjectFileELF::
 257 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 258                          Mangler *Mang, const TargetMachine &TM) const {
 259   StringRef SectionName = GV->getSection();
 260
 261   // Infer section flags from the section name if we can.
 262   Kind = getELFKindForNamedSection(SectionName, Kind);
 263
 264   return getContext().getELFSection(SectionName,
 265                                     getELFSectionType(SectionName, Kind),
 266                                     getELFSectionFlags(Kind), Kind);
 267 }
 268
 269 /// getSectionPrefixForGlobal - Return the section prefix name used by options
 270 /// FunctionsSections and DataSections.
 271 static const char *getSectionPrefixForGlobal(SectionKind Kind) {
 272   if (Kind.isText())                 return ".text.";
 273   if (Kind.isReadOnly())             return ".rodata.";
 274
 275   if (Kind.isThreadData())           return ".tdata.";
 276   if (Kind.isThreadBSS())            return ".tbss.";
 277
 278   if (Kind.isDataNoRel())            return ".data.";
 279   if (Kind.isDataRelLocal())         return ".data.rel.local.";
 280   if (Kind.isDataRel())              return ".data.rel.";
 281   if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local.";
 282
 283   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 284   return ".data.rel.ro.";
 285 }
 286
 287
 288 const MCSection *TargetLoweringObjectFileELF::
 289 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 290                        Mangler *Mang, const TargetMachine &TM) const {
 291   // If we have -ffunction-section or -fdata-section then we should emit the
 292   // global value to a uniqued section specifically for it.
 293   bool EmitUniquedSection;
 294   if (Kind.isText())
 295     EmitUniquedSection = TM.getFunctionSections();
 296   else
 297     EmitUniquedSection = TM.getDataSections();
 298
 299   // If this global is linkonce/weak and the target handles this by emitting it
 300   // into a 'uniqued' section name, create and return the section now.
 301   if ((GV->isWeakForLinker() || EmitUniquedSection) &&
 302       !Kind.isCommon() && !Kind.isBSS()) {
 303     const char *Prefix;
 304     Prefix = getSectionPrefixForGlobal(Kind);
 305
 306     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
 307     MCSymbol *Sym = Mang->getSymbol(GV);
 308     Name.append(Sym->getName().begin(), Sym->getName().end());
 309     StringRef Group = "";
 310     unsigned Flags = getELFSectionFlags(Kind);
 311     if (GV->isWeakForLinker()) {
 312       Group = Sym->getName();
 313       Flags |= ELF::SHF_GROUP;
 314     }
 315
 316     return getContext().getELFSection(Name.str(),
 317                                       getELFSectionType(Name.str(), Kind),
 318                                       Flags, Kind, 0, Group);
 319   }
 320
 321   if (Kind.isText()) return TextSection;
 322
 323   if (Kind.isMergeable1ByteCString() ||
 324       Kind.isMergeable2ByteCString() ||
 325       Kind.isMergeable4ByteCString()) {
 326
 327     // We also need alignment here.
 328     // FIXME: this is getting the alignment of the character, not the
 329     // alignment of the global!
 330     unsigned Align =
 331       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
 332
 333     const char *SizeSpec = ".rodata.str1.";
 334     if (Kind.isMergeable2ByteCString())
 335       SizeSpec = ".rodata.str2.";
 336     else if (Kind.isMergeable4ByteCString())
 337       SizeSpec = ".rodata.str4.";
 338     else
 339       assert(Kind.isMergeable1ByteCString() && "unknown string width");
 340
 341
 342     std::string Name = SizeSpec + utostr(Align);
 343     return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
 344                                       ELF::SHF_ALLOC |
 345                                       ELF::SHF_MERGE |
 346                                       ELF::SHF_STRINGS,
 347                                       Kind);
 348   }
 349
 350   if (Kind.isMergeableConst()) {
 351     if (Kind.isMergeableConst4() && MergeableConst4Section)
 352       return MergeableConst4Section;
 353     if (Kind.isMergeableConst8() && MergeableConst8Section)
 354       return MergeableConst8Section;
 355     if (Kind.isMergeableConst16() && MergeableConst16Section)
 356       return MergeableConst16Section;
 357     return ReadOnlySection;  // .const
 358   }
 359
 360   if (Kind.isReadOnly())             return ReadOnlySection;
 361
 362   if (Kind.isThreadData())           return TLSDataSection;
 363   if (Kind.isThreadBSS())            return TLSBSSSection;
 364
 365   // Note: we claim that common symbols are put in BSSSection, but they are
 366   // really emitted with the magic .comm directive, which creates a symbol table
 367   // entry but not a section.
 368   if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
 369
 370   if (Kind.isDataNoRel())            return DataSection;
 371   if (Kind.isDataRelLocal())         return DataRelLocalSection;
 372   if (Kind.isDataRel())              return DataRelSection;
 373   if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
 374
 375   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 376   return DataRelROSection;
 377 }
 378
 379 /// getSectionForConstant - Given a mergeable constant with the
 380 /// specified size and relocation information, return a section that it
 381 /// should be placed in.
 382 const MCSection *TargetLoweringObjectFileELF::
 383 getSectionForConstant(SectionKind Kind) const {
 384   if (Kind.isMergeableConst4() && MergeableConst4Section)
 385     return MergeableConst4Section;
 386   if (Kind.isMergeableConst8() && MergeableConst8Section)
 387     return MergeableConst8Section;
 388   if (Kind.isMergeableConst16() && MergeableConst16Section)
 389     return MergeableConst16Section;
 390   if (Kind.isReadOnly())
 391     return ReadOnlySection;
 392
 393   if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
 394   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 395   return DataRelROSection;
 396 }
 397
 398 const MCExpr *TargetLoweringObjectFileELF::
 399 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
 400                                MachineModuleInfo *MMI,
 401                                unsigned Encoding, MCStreamer &Streamer) const {
 402
 403   if (Encoding & dwarf::DW_EH_PE_indirect) {
 404     MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
 405
 406     SmallString<128> Name;
 407     Mang->getNameWithPrefix(Name, GV, true);
 408     Name += ".DW.stub";
 409
 410     // Add information about the stub reference to ELFMMI so that the stub
 411     // gets emitted by the asmprinter.
 412     MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
 413     MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
 414     if (StubSym.getPointer() == 0) {
 415       MCSymbol *Sym = Mang->getSymbol(GV);
 416       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
 417     }
 418
 419     return TargetLoweringObjectFile::
 420       getExprForDwarfReference(SSym, Mang, MMI,
 421                                Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
 422   }
 423
 424   return TargetLoweringObjectFile::
 425     getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
 426 }
 427
 428 //===----------------------------------------------------------------------===//
 429 //                                 MachO
 430 //===----------------------------------------------------------------------===//
 431
 432 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
 433                                                const TargetMachine &TM) {
 434   // _foo.eh symbols are currently always exported so that the linker knows
 435   // about them.  This is not necessary on 10.6 and later, but it
 436   // doesn't hurt anything.
 437   // FIXME: I need to get this from Triple.
 438   IsFunctionEHSymbolGlobal = true;
 439   IsFunctionEHFrameSymbolPrivate = false;
 440   SupportsWeakOmittedEHFrame = false;
 441
 442   Triple T(((LLVMTargetMachine&)TM).getTargetTriple());
 443   if (T.getOS() == Triple::Darwin) {
 444     switch (T.getDarwinMajorNumber()) {
 445     case 7:  // 10.3 Panther.
 446     case 8:  // 10.4 Tiger.
 447       CommDirectiveSupportsAlignment = false;
 448       break;
 449     case 9:   // 10.5 Leopard.
 450     case 10:  // 10.6 SnowLeopard.
 451       break;
 452     }
 453   }
 454
 455   TargetLoweringObjectFile::Initialize(Ctx, TM);
 456
 457   TextSection // .text
 458     = getContext().getMachOSection("__TEXT", "__text",
 459                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 460                                    SectionKind::getText());
 461   DataSection // .data
 462     = getContext().getMachOSection("__DATA", "__data", 0,
 463                                    SectionKind::getDataRel());
 464
 465   TLSDataSection // .tdata
 466     = getContext().getMachOSection("__DATA", "__thread_data",
 467                                    MCSectionMachO::S_THREAD_LOCAL_REGULAR,
 468                                    SectionKind::getDataRel());
 469   TLSBSSSection // .tbss
 470     = getContext().getMachOSection("__DATA", "__thread_bss",
 471                                    MCSectionMachO::S_THREAD_LOCAL_ZEROFILL,
 472                                    SectionKind::getThreadBSS());
 473
 474   // TODO: Verify datarel below.
 475   TLSTLVSection // .tlv
 476     = getContext().getMachOSection("__DATA", "__thread_vars",
 477                                    MCSectionMachO::S_THREAD_LOCAL_VARIABLES,
 478                                    SectionKind::getDataRel());
 479
 480   TLSThreadInitSection
 481     = getContext().getMachOSection("__DATA", "__thread_init",
 482                           MCSectionMachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
 483                           SectionKind::getDataRel());
 484
 485   CStringSection // .cstring
 486     = getContext().getMachOSection("__TEXT", "__cstring",
 487                                    MCSectionMachO::S_CSTRING_LITERALS,
 488                                    SectionKind::getMergeable1ByteCString());
 489   UStringSection
 490     = getContext().getMachOSection("__TEXT","__ustring", 0,
 491                                    SectionKind::getMergeable2ByteCString());
 492   FourByteConstantSection // .literal4
 493     = getContext().getMachOSection("__TEXT", "__literal4",
 494                                    MCSectionMachO::S_4BYTE_LITERALS,
 495                                    SectionKind::getMergeableConst4());
 496   EightByteConstantSection // .literal8
 497     = getContext().getMachOSection("__TEXT", "__literal8",
 498                                    MCSectionMachO::S_8BYTE_LITERALS,
 499                                    SectionKind::getMergeableConst8());
 500
 501   // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
 502   // to using it in -static mode.
 503   SixteenByteConstantSection = 0;
 504   if (TM.getRelocationModel() != Reloc::Static &&
 505       TM.getTargetData()->getPointerSize() == 32)
 506     SixteenByteConstantSection =   // .literal16
 507       getContext().getMachOSection("__TEXT", "__literal16",
 508                                    MCSectionMachO::S_16BYTE_LITERALS,
 509                                    SectionKind::getMergeableConst16());
 510
 511   ReadOnlySection  // .const
 512     = getContext().getMachOSection("__TEXT", "__const", 0,
 513                                    SectionKind::getReadOnly());
 514
 515   TextCoalSection
 516     = getContext().getMachOSection("__TEXT", "__textcoal_nt",
 517                                    MCSectionMachO::S_COALESCED |
 518                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 519                                    SectionKind::getText());
 520   ConstTextCoalSection
 521     = getContext().getMachOSection("__TEXT", "__const_coal",
 522                                    MCSectionMachO::S_COALESCED,
 523                                    SectionKind::getReadOnly());
 524   ConstDataSection  // .const_data
 525     = getContext().getMachOSection("__DATA", "__const", 0,
 526                                    SectionKind::getReadOnlyWithRel());
 527   DataCoalSection
 528     = getContext().getMachOSection("__DATA","__datacoal_nt",
 529                                    MCSectionMachO::S_COALESCED,
 530                                    SectionKind::getDataRel());
 531   DataCommonSection
 532     = getContext().getMachOSection("__DATA","__common",
 533                                    MCSectionMachO::S_ZEROFILL,
 534                                    SectionKind::getBSS());
 535   DataBSSSection
 536     = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
 537                                    SectionKind::getBSS());
 538
 539
 540   LazySymbolPointerSection
 541     = getContext().getMachOSection("__DATA", "__la_symbol_ptr",
 542                                    MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
 543                                    SectionKind::getMetadata());
 544   NonLazySymbolPointerSection
 545     = getContext().getMachOSection("__DATA", "__nl_symbol_ptr",
 546                                    MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
 547                                    SectionKind::getMetadata());
 548
 549   if (TM.getRelocationModel() == Reloc::Static) {
 550     StaticCtorSection
 551       = getContext().getMachOSection("__TEXT", "__constructor", 0,
 552                                      SectionKind::getDataRel());
 553     StaticDtorSection
 554       = getContext().getMachOSection("__TEXT", "__destructor", 0,
 555                                      SectionKind::getDataRel());
 556   } else {
 557     StaticCtorSection
 558       = getContext().getMachOSection("__DATA", "__mod_init_func",
 559                                      MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
 560                                      SectionKind::getDataRel());
 561     StaticDtorSection
 562       = getContext().getMachOSection("__DATA", "__mod_term_func",
 563                                      MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
 564                                      SectionKind::getDataRel());
 565   }
 566
 567   // Exception Handling.
 568   LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0,
 569                                              SectionKind::getReadOnlyWithRel());
 570   // Debug Information.
 571   DwarfAbbrevSection =
 572     getContext().getMachOSection("__DWARF", "__debug_abbrev",
 573                                  MCSectionMachO::S_ATTR_DEBUG,
 574                                  SectionKind::getMetadata());
 575   DwarfInfoSection =
 576     getContext().getMachOSection("__DWARF", "__debug_info",
 577                                  MCSectionMachO::S_ATTR_DEBUG,
 578                                  SectionKind::getMetadata());
 579   DwarfLineSection =
 580     getContext().getMachOSection("__DWARF", "__debug_line",
 581                                  MCSectionMachO::S_ATTR_DEBUG,
 582                                  SectionKind::getMetadata());
 583   DwarfFrameSection =
 584     getContext().getMachOSection("__DWARF", "__debug_frame",
 585                                  MCSectionMachO::S_ATTR_DEBUG,
 586                                  SectionKind::getMetadata());
 587   DwarfPubNamesSection =
 588     getContext().getMachOSection("__DWARF", "__debug_pubnames",
 589                                  MCSectionMachO::S_ATTR_DEBUG,
 590                                  SectionKind::getMetadata());
 591   DwarfPubTypesSection =
 592     getContext().getMachOSection("__DWARF", "__debug_pubtypes",
 593                                  MCSectionMachO::S_ATTR_DEBUG,
 594                                  SectionKind::getMetadata());
 595   DwarfStrSection =
 596     getContext().getMachOSection("__DWARF", "__debug_str",
 597                                  MCSectionMachO::S_ATTR_DEBUG,
 598                                  SectionKind::getMetadata());
 599   DwarfLocSection =
 600     getContext().getMachOSection("__DWARF", "__debug_loc",
 601                                  MCSectionMachO::S_ATTR_DEBUG,
 602                                  SectionKind::getMetadata());
 603   DwarfARangesSection =
 604     getContext().getMachOSection("__DWARF", "__debug_aranges",
 605                                  MCSectionMachO::S_ATTR_DEBUG,
 606                                  SectionKind::getMetadata());
 607   DwarfRangesSection =
 608     getContext().getMachOSection("__DWARF", "__debug_ranges",
 609                                  MCSectionMachO::S_ATTR_DEBUG,
 610                                  SectionKind::getMetadata());
 611   DwarfMacroInfoSection =
 612     getContext().getMachOSection("__DWARF", "__debug_macinfo",
 613                                  MCSectionMachO::S_ATTR_DEBUG,
 614                                  SectionKind::getMetadata());
 615   DwarfDebugInlineSection =
 616     getContext().getMachOSection("__DWARF", "__debug_inlined",
 617                                  MCSectionMachO::S_ATTR_DEBUG,
 618                                  SectionKind::getMetadata());
 619
 620   TLSExtraDataSection = TLSTLVSection;
 621 }
 622
 623 const MCSection *TargetLoweringObjectFileMachO::getEHFrameSection() const {
 624   return getContext().getMachOSection("__TEXT", "__eh_frame",
 625                                       MCSectionMachO::S_COALESCED |
 626                                       MCSectionMachO::S_ATTR_NO_TOC |
 627                                       MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
 628                                       MCSectionMachO::S_ATTR_LIVE_SUPPORT,
 629                                       SectionKind::getReadOnly());
 630 }
 631
 632 const MCSection *TargetLoweringObjectFileMachO::
 633 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 634                          Mangler *Mang, const TargetMachine &TM) const {
 635   // Parse the section specifier and create it if valid.
 636   StringRef Segment, Section;
 637   unsigned TAA = (unsigned)MCSectionMachO::SECTION_ATTRIBUTES, StubSize = 0;
 638   std::string ErrorCode =
 639     MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
 640                                           TAA, StubSize);
 641   if (!ErrorCode.empty()) {
 642     // If invalid, report the error with report_fatal_error.
 643     report_fatal_error("Global variable '" + GV->getNameStr() +
 644                       "' has an invalid section specifier '" + GV->getSection()+
 645                       "': " + ErrorCode + ".");
 646     // Fall back to dropping it into the data section.
 647     return DataSection;
 648   }
 649
 650   bool TAAWasSet = (TAA != MCSectionMachO::SECTION_ATTRIBUTES);
 651   if (!TAAWasSet)
 652     TAA = 0;      // Sensible default if this is a new section.
 653
 654   // Get the section.
 655   const MCSectionMachO *S =
 656     getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
 657
 658   // If TAA wasn't set by ParseSectionSpecifier() above,
 659   // use the value returned by getMachOSection() as a default.
 660   if (!TAAWasSet)
 661     TAA = S->getTypeAndAttributes();
 662
 663   // Okay, now that we got the section, verify that the TAA & StubSize agree.
 664   // If the user declared multiple globals with different section flags, we need
 665   // to reject it here.
 666   if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
 667     // If invalid, report the error with report_fatal_error.
 668     report_fatal_error("Global variable '" + GV->getNameStr() +
 669                       "' section type or attributes does not match previous"
 670                       " section specifier");
 671   }
 672
 673   return S;
 674 }
 675
 676 const MCSection *TargetLoweringObjectFileMachO::
 677 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 678                        Mangler *Mang, const TargetMachine &TM) const {
 679
 680   // Handle thread local data.
 681   if (Kind.isThreadBSS()) return TLSBSSSection;
 682   if (Kind.isThreadData()) return TLSDataSection;
 683
 684   if (Kind.isText())
 685     return GV->isWeakForLinker() ? TextCoalSection : TextSection;
 686
 687   // If this is weak/linkonce, put this in a coalescable section, either in text
 688   // or data depending on if it is writable.
 689   if (GV->isWeakForLinker()) {
 690     if (Kind.isReadOnly())
 691       return ConstTextCoalSection;
 692     return DataCoalSection;
 693   }
 694
 695   // FIXME: Alignment check should be handled by section classifier.
 696   if (Kind.isMergeable1ByteCString() &&
 697       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
 698     return CStringSection;
 699
 700   // Do not put 16-bit arrays in the UString section if they have an
 701   // externally visible label, this runs into issues with certain linker
 702   // versions.
 703   if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
 704       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
 705     return UStringSection;
 706
 707   if (Kind.isMergeableConst()) {
 708     if (Kind.isMergeableConst4())
 709       return FourByteConstantSection;
 710     if (Kind.isMergeableConst8())
 711       return EightByteConstantSection;
 712     if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 713       return SixteenByteConstantSection;
 714   }
 715
 716   // Otherwise, if it is readonly, but not something we can specially optimize,
 717   // just drop it in .const.
 718   if (Kind.isReadOnly())
 719     return ReadOnlySection;
 720
 721   // If this is marked const, put it into a const section.  But if the dynamic
 722   // linker needs to write to it, put it in the data segment.
 723   if (Kind.isReadOnlyWithRel())
 724     return ConstDataSection;
 725
 726   // Put zero initialized globals with strong external linkage in the
 727   // DATA, __common section with the .zerofill directive.
 728   if (Kind.isBSSExtern())
 729     return DataCommonSection;
 730
 731   // Put zero initialized globals with local linkage in __DATA,__bss directive
 732   // with the .zerofill directive (aka .lcomm).
 733   if (Kind.isBSSLocal())
 734     return DataBSSSection;
 735
 736   // Otherwise, just drop the variable in the normal data section.
 737   return DataSection;
 738 }
 739
 740 const MCSection *
 741 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
 742   // If this constant requires a relocation, we have to put it in the data
 743   // segment, not in the text segment.
 744   if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
 745     return ConstDataSection;
 746
 747   if (Kind.isMergeableConst4())
 748     return FourByteConstantSection;
 749   if (Kind.isMergeableConst8())
 750     return EightByteConstantSection;
 751   if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 752     return SixteenByteConstantSection;
 753   return ReadOnlySection;  // .const
 754 }
 755
 756 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
 757 /// not to emit the UsedDirective for some symbols in llvm.used.
 758 // FIXME: REMOVE this (rdar://7071300)
 759 bool TargetLoweringObjectFileMachO::
 760 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
 761   /// On Darwin, internally linked data beginning with "L" or "l" does not have
 762   /// the directive emitted (this occurs in ObjC metadata).
 763   if (!GV) return false;
 764
 765   // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
 766   if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
 767     // FIXME: ObjC metadata is currently emitted as internal symbols that have
 768     // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
 769     // this horrible hack can go away.
 770     MCSymbol *Sym = Mang->getSymbol(GV);
 771     if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
 772       return false;
 773   }
 774
 775   return true;
 776 }
 777
 778 const MCExpr *TargetLoweringObjectFileMachO::
 779 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
 780                                MachineModuleInfo *MMI, unsigned Encoding,
 781                                MCStreamer &Streamer) const {
 782   // The mach-o version of this method defaults to returning a stub reference.
 783
 784   if (Encoding & DW_EH_PE_indirect) {
 785     MachineModuleInfoMachO &MachOMMI =
 786       MMI->getObjFileInfo<MachineModuleInfoMachO>();
 787
 788     SmallString<128> Name;
 789     Mang->getNameWithPrefix(Name, GV, true);
 790     Name += "$non_lazy_ptr";
 791
 792     // Add information about the stub reference to MachOMMI so that the stub
 793     // gets emitted by the asmprinter.
 794     MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
 795     MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
 796     if (StubSym.getPointer() == 0) {
 797       MCSymbol *Sym = Mang->getSymbol(GV);
 798       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
 799     }
 800
 801     return TargetLoweringObjectFile::
 802       getExprForDwarfReference(SSym, Mang, MMI,
 803                                Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
 804   }
 805
 806   return TargetLoweringObjectFile::
 807     getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
 808 }
 809
 810 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const {
 811   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
 812 }
 813
 814 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const {
 815   return DW_EH_PE_pcrel;
 816 }
 817
 818 unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const {
 819   return DW_EH_PE_pcrel;
 820 }
 821
 822 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const {
 823   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
 824 }
 825
 826 //===----------------------------------------------------------------------===//
 827 //                                  COFF
 828 //===----------------------------------------------------------------------===//
 829
 830 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
 831                                               const TargetMachine &TM) {
 832   TargetLoweringObjectFile::Initialize(Ctx, TM);
 833   TextSection =
 834     getContext().getCOFFSection(".text",
 835                                 COFF::IMAGE_SCN_CNT_CODE |
 836                                 COFF::IMAGE_SCN_MEM_EXECUTE |
 837                                 COFF::IMAGE_SCN_MEM_READ,
 838                                 SectionKind::getText());
 839   DataSection =
 840     getContext().getCOFFSection(".data",
 841                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 842                                 COFF::IMAGE_SCN_MEM_READ |
 843                                 COFF::IMAGE_SCN_MEM_WRITE,
 844                                 SectionKind::getDataRel());
 845   ReadOnlySection =
 846     getContext().getCOFFSection(".rdata",
 847                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 848                                 COFF::IMAGE_SCN_MEM_READ,
 849                                 SectionKind::getReadOnly());
 850   StaticCtorSection =
 851     getContext().getCOFFSection(".ctors",
 852                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 853                                 COFF::IMAGE_SCN_MEM_READ |
 854                                 COFF::IMAGE_SCN_MEM_WRITE,
 855                                 SectionKind::getDataRel());
 856   StaticDtorSection =
 857     getContext().getCOFFSection(".dtors",
 858                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 859                                 COFF::IMAGE_SCN_MEM_READ |
 860                                 COFF::IMAGE_SCN_MEM_WRITE,
 861                                 SectionKind::getDataRel());
 862
 863   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
 864   // though it contains relocatable pointers.  In PIC mode, this is probably a
 865   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
 866   // adjusted or this should be a data section.
 867   LSDASection =
 868     getContext().getCOFFSection(".gcc_except_table",
 869                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 870                                 COFF::IMAGE_SCN_MEM_READ,
 871                                 SectionKind::getReadOnly());
 872   // Debug info.
 873   DwarfAbbrevSection =
 874     getContext().getCOFFSection(".debug_abbrev",
 875                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 876                                 COFF::IMAGE_SCN_MEM_READ,
 877                                 SectionKind::getMetadata());
 878   DwarfInfoSection =
 879     getContext().getCOFFSection(".debug_info",
 880                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 881                                 COFF::IMAGE_SCN_MEM_READ,
 882                                 SectionKind::getMetadata());
 883   DwarfLineSection =
 884     getContext().getCOFFSection(".debug_line",
 885                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 886                                 COFF::IMAGE_SCN_MEM_READ,
 887                                 SectionKind::getMetadata());
 888   DwarfFrameSection =
 889     getContext().getCOFFSection(".debug_frame",
 890                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 891                                 COFF::IMAGE_SCN_MEM_READ,
 892                                 SectionKind::getMetadata());
 893   DwarfPubNamesSection =
 894     getContext().getCOFFSection(".debug_pubnames",
 895                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 896                                 COFF::IMAGE_SCN_MEM_READ,
 897                                 SectionKind::getMetadata());
 898   DwarfPubTypesSection =
 899     getContext().getCOFFSection(".debug_pubtypes",
 900                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 901                                 COFF::IMAGE_SCN_MEM_READ,
 902                                 SectionKind::getMetadata());
 903   DwarfStrSection =
 904     getContext().getCOFFSection(".debug_str",
 905                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 906                                 COFF::IMAGE_SCN_MEM_READ,
 907                                 SectionKind::getMetadata());
 908   DwarfLocSection =
 909     getContext().getCOFFSection(".debug_loc",
 910                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 911                                 COFF::IMAGE_SCN_MEM_READ,
 912                                 SectionKind::getMetadata());
 913   DwarfARangesSection =
 914     getContext().getCOFFSection(".debug_aranges",
 915                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 916                                 COFF::IMAGE_SCN_MEM_READ,
 917                                 SectionKind::getMetadata());
 918   DwarfRangesSection =
 919     getContext().getCOFFSection(".debug_ranges",
 920                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 921                                 COFF::IMAGE_SCN_MEM_READ,
 922                                 SectionKind::getMetadata());
 923   DwarfMacroInfoSection =
 924     getContext().getCOFFSection(".debug_macinfo",
 925                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 926                                 COFF::IMAGE_SCN_MEM_READ,
 927                                 SectionKind::getMetadata());
 928
 929   DrectveSection =
 930     getContext().getCOFFSection(".drectve",
 931                                 COFF::IMAGE_SCN_LNK_INFO,
 932                                 SectionKind::getMetadata());
 933 }
 934
 935 const MCSection *TargetLoweringObjectFileCOFF::getEHFrameSection() const {
 936   return getContext().getCOFFSection(".eh_frame",
 937                                      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 938                                      COFF::IMAGE_SCN_MEM_READ |
 939                                      COFF::IMAGE_SCN_MEM_WRITE,
 940                                      SectionKind::getDataRel());
 941 }
 942
 943
 944 static unsigned
 945 getCOFFSectionFlags(SectionKind K) {
 946   unsigned Flags = 0;
 947
 948   if (K.isMetadata())
 949     Flags |=
 950       COFF::IMAGE_SCN_MEM_DISCARDABLE;
 951   else if (K.isText())
 952     Flags |=
 953       COFF::IMAGE_SCN_MEM_EXECUTE |
 954       COFF::IMAGE_SCN_MEM_READ |
 955       COFF::IMAGE_SCN_CNT_CODE;
 956   else if (K.isBSS ())
 957     Flags |=
 958       COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
 959       COFF::IMAGE_SCN_MEM_READ |
 960       COFF::IMAGE_SCN_MEM_WRITE;
 961   else if (K.isReadOnly())
 962     Flags |=
 963       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 964       COFF::IMAGE_SCN_MEM_READ;
 965   else if (K.isWriteable())
 966     Flags |=
 967       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 968       COFF::IMAGE_SCN_MEM_READ |
 969       COFF::IMAGE_SCN_MEM_WRITE;
 970
 971   return Flags;
 972 }
 973
 974 const MCSection *TargetLoweringObjectFileCOFF::
 975 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 976                          Mangler *Mang, const TargetMachine &TM) const {
 977   return getContext().getCOFFSection(GV->getSection(),
 978                                      getCOFFSectionFlags(Kind),
 979                                      Kind);
 980 }
 981
 982 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
 983   if (Kind.isText())
 984     return ".text$";
 985   if (Kind.isBSS ())
 986     return ".bss$";
 987   if (Kind.isWriteable())
 988     return ".data$";
 989   return ".rdata$";
 990 }
 991
 992
 993 const MCSection *TargetLoweringObjectFileCOFF::
 994 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 995                        Mangler *Mang, const TargetMachine &TM) const {
 996   assert(!Kind.isThreadLocal() && "Doesn't support TLS");
 997
 998   // If this global is linkonce/weak and the target handles this by emitting it
 999   // into a 'uniqued' section name, create and return the section now.
1000   if (GV->isWeakForLinker()) {
1001     const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
1002     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
1003     MCSymbol *Sym = Mang->getSymbol(GV);
1004     Name.append(Sym->getName().begin() + 1, Sym->getName().end());
1005
1006     unsigned Characteristics = getCOFFSectionFlags(Kind);
1007
1008     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
1009
1010     return getContext().getCOFFSection(Name.str(), Characteristics,
1011                           COFF::IMAGE_COMDAT_SELECT_ANY, Kind);
1012   }
1013
1014   if (Kind.isText())
1015     return getTextSection();
1016
1017   return getDataSection();
1018 }
1019