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 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) {
 270   if (Kind.isText())                 return ".gnu.linkonce.t.";
 271   if (Kind.isReadOnly())             return ".gnu.linkonce.r.";
 272
 273   if (Kind.isThreadData())           return ".gnu.linkonce.td.";
 274   if (Kind.isThreadBSS())            return ".gnu.linkonce.tb.";
 275
 276   if (Kind.isDataNoRel())            return ".gnu.linkonce.d.";
 277   if (Kind.isDataRelLocal())         return ".gnu.linkonce.d.rel.local.";
 278   if (Kind.isDataRel())              return ".gnu.linkonce.d.rel.";
 279   if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local.";
 280
 281   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 282   return ".gnu.linkonce.d.rel.ro.";
 283 }
 284
 285 /// getSectionPrefixForGlobal - Return the section prefix name used by options
 286 /// FunctionsSections and DataSections.
 287 static const char *getSectionPrefixForGlobal(SectionKind Kind) {
 288   if (Kind.isText())                 return ".text.";
 289   if (Kind.isReadOnly())             return ".rodata.";
 290
 291   if (Kind.isThreadData())           return ".tdata.";
 292   if (Kind.isThreadBSS())            return ".tbss.";
 293
 294   if (Kind.isDataNoRel())            return ".data.";
 295   if (Kind.isDataRelLocal())         return ".data.rel.local.";
 296   if (Kind.isDataRel())              return ".data.rel.";
 297   if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local.";
 298
 299   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 300   return ".data.rel.ro.";
 301 }
 302
 303
 304 const MCSection *TargetLoweringObjectFileELF::
 305 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 306                        Mangler *Mang, const TargetMachine &TM) const {
 307   // If we have -ffunction-section or -fdata-section then we should emit the
 308   // global value to a uniqued section specifically for it.
 309   bool EmitUniquedSection;
 310   if (Kind.isText())
 311     EmitUniquedSection = TM.getFunctionSections();
 312   else
 313     EmitUniquedSection = TM.getDataSections();
 314
 315   // If this global is linkonce/weak and the target handles this by emitting it
 316   // into a 'uniqued' section name, create and return the section now.
 317   if ((GV->isWeakForLinker() || EmitUniquedSection) &&
 318       !Kind.isCommon() && !Kind.isBSS()) {
 319     const char *Prefix;
 320     if (GV->isWeakForLinker())
 321       Prefix = getSectionPrefixForUniqueGlobal(Kind);
 322     else {
 323       assert(EmitUniquedSection);
 324       Prefix = getSectionPrefixForGlobal(Kind);
 325     }
 326
 327     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
 328     MCSymbol *Sym = Mang->getSymbol(GV);
 329     Name.append(Sym->getName().begin(), Sym->getName().end());
 330     return getContext().getELFSection(Name.str(),
 331                                       getELFSectionType(Name.str(), Kind),
 332                                       getELFSectionFlags(Kind), Kind);
 333   }
 334
 335   if (Kind.isText()) return TextSection;
 336
 337   if (Kind.isMergeable1ByteCString() ||
 338       Kind.isMergeable2ByteCString() ||
 339       Kind.isMergeable4ByteCString()) {
 340
 341     // We also need alignment here.
 342     // FIXME: this is getting the alignment of the character, not the
 343     // alignment of the global!
 344     unsigned Align =
 345       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
 346
 347     const char *SizeSpec = ".rodata.str1.";
 348     if (Kind.isMergeable2ByteCString())
 349       SizeSpec = ".rodata.str2.";
 350     else if (Kind.isMergeable4ByteCString())
 351       SizeSpec = ".rodata.str4.";
 352     else
 353       assert(Kind.isMergeable1ByteCString() && "unknown string width");
 354
 355
 356     std::string Name = SizeSpec + utostr(Align);
 357     return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
 358                                       ELF::SHF_ALLOC |
 359                                       ELF::SHF_MERGE |
 360                                       ELF::SHF_STRINGS,
 361                                       Kind);
 362   }
 363
 364   if (Kind.isMergeableConst()) {
 365     if (Kind.isMergeableConst4() && MergeableConst4Section)
 366       return MergeableConst4Section;
 367     if (Kind.isMergeableConst8() && MergeableConst8Section)
 368       return MergeableConst8Section;
 369     if (Kind.isMergeableConst16() && MergeableConst16Section)
 370       return MergeableConst16Section;
 371     return ReadOnlySection;  // .const
 372   }
 373
 374   if (Kind.isReadOnly())             return ReadOnlySection;
 375
 376   if (Kind.isThreadData())           return TLSDataSection;
 377   if (Kind.isThreadBSS())            return TLSBSSSection;
 378
 379   // Note: we claim that common symbols are put in BSSSection, but they are
 380   // really emitted with the magic .comm directive, which creates a symbol table
 381   // entry but not a section.
 382   if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
 383
 384   if (Kind.isDataNoRel())            return DataSection;
 385   if (Kind.isDataRelLocal())         return DataRelLocalSection;
 386   if (Kind.isDataRel())              return DataRelSection;
 387   if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
 388
 389   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 390   return DataRelROSection;
 391 }
 392
 393 /// getSectionForConstant - Given a mergeable constant with the
 394 /// specified size and relocation information, return a section that it
 395 /// should be placed in.
 396 const MCSection *TargetLoweringObjectFileELF::
 397 getSectionForConstant(SectionKind Kind) const {
 398   if (Kind.isMergeableConst4() && MergeableConst4Section)
 399     return MergeableConst4Section;
 400   if (Kind.isMergeableConst8() && MergeableConst8Section)
 401     return MergeableConst8Section;
 402   if (Kind.isMergeableConst16() && MergeableConst16Section)
 403     return MergeableConst16Section;
 404   if (Kind.isReadOnly())
 405     return ReadOnlySection;
 406
 407   if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
 408   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 409   return DataRelROSection;
 410 }
 411
 412 const MCExpr *TargetLoweringObjectFileELF::
 413 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
 414                                MachineModuleInfo *MMI,
 415                                unsigned Encoding, MCStreamer &Streamer) const {
 416
 417   if (Encoding & dwarf::DW_EH_PE_indirect) {
 418     MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
 419
 420     SmallString<128> Name;
 421     Mang->getNameWithPrefix(Name, GV, true);
 422     Name += ".DW.stub";
 423
 424     // Add information about the stub reference to ELFMMI so that the stub
 425     // gets emitted by the asmprinter.
 426     MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
 427     MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
 428     if (StubSym.getPointer() == 0) {
 429       MCSymbol *Sym = Mang->getSymbol(GV);
 430       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
 431     }
 432
 433     return TargetLoweringObjectFile::
 434       getExprForDwarfReference(SSym, Mang, MMI,
 435                                Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
 436   }
 437
 438   return TargetLoweringObjectFile::
 439     getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
 440 }
 441
 442 //===----------------------------------------------------------------------===//
 443 //                                 MachO
 444 //===----------------------------------------------------------------------===//
 445
 446 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
 447                                                const TargetMachine &TM) {
 448   // _foo.eh symbols are currently always exported so that the linker knows
 449   // about them.  This is not necessary on 10.6 and later, but it
 450   // doesn't hurt anything.
 451   // FIXME: I need to get this from Triple.
 452   IsFunctionEHSymbolGlobal = true;
 453   IsFunctionEHFrameSymbolPrivate = false;
 454   SupportsWeakOmittedEHFrame = false;
 455
 456   Triple T(((LLVMTargetMachine&)TM).getTargetTriple());
 457   if (T.getOS() == Triple::Darwin) {
 458     switch (T.getDarwinMajorNumber()) {
 459     case 7:  // 10.3 Panther.
 460     case 8:  // 10.4 Tiger.
 461       CommDirectiveSupportsAlignment = false;
 462       break;
 463     case 9:   // 10.5 Leopard.
 464     case 10:  // 10.6 SnowLeopard.
 465       break;
 466     }
 467   }
 468
 469   TargetLoweringObjectFile::Initialize(Ctx, TM);
 470
 471   TextSection // .text
 472     = getContext().getMachOSection("__TEXT", "__text",
 473                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 474                                    SectionKind::getText());
 475   DataSection // .data
 476     = getContext().getMachOSection("__DATA", "__data", 0,
 477                                    SectionKind::getDataRel());
 478
 479   TLSDataSection // .tdata
 480     = getContext().getMachOSection("__DATA", "__thread_data",
 481                                    MCSectionMachO::S_THREAD_LOCAL_REGULAR,
 482                                    SectionKind::getDataRel());
 483   TLSBSSSection // .tbss
 484     = getContext().getMachOSection("__DATA", "__thread_bss",
 485                                    MCSectionMachO::S_THREAD_LOCAL_ZEROFILL,
 486                                    SectionKind::getThreadBSS());
 487
 488   // TODO: Verify datarel below.
 489   TLSTLVSection // .tlv
 490     = getContext().getMachOSection("__DATA", "__thread_vars",
 491                                    MCSectionMachO::S_THREAD_LOCAL_VARIABLES,
 492                                    SectionKind::getDataRel());
 493
 494   TLSThreadInitSection
 495     = getContext().getMachOSection("__DATA", "__thread_init",
 496                           MCSectionMachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
 497                           SectionKind::getDataRel());
 498
 499   CStringSection // .cstring
 500     = getContext().getMachOSection("__TEXT", "__cstring",
 501                                    MCSectionMachO::S_CSTRING_LITERALS,
 502                                    SectionKind::getMergeable1ByteCString());
 503   UStringSection
 504     = getContext().getMachOSection("__TEXT","__ustring", 0,
 505                                    SectionKind::getMergeable2ByteCString());
 506   FourByteConstantSection // .literal4
 507     = getContext().getMachOSection("__TEXT", "__literal4",
 508                                    MCSectionMachO::S_4BYTE_LITERALS,
 509                                    SectionKind::getMergeableConst4());
 510   EightByteConstantSection // .literal8
 511     = getContext().getMachOSection("__TEXT", "__literal8",
 512                                    MCSectionMachO::S_8BYTE_LITERALS,
 513                                    SectionKind::getMergeableConst8());
 514
 515   // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
 516   // to using it in -static mode.
 517   SixteenByteConstantSection = 0;
 518   if (TM.getRelocationModel() != Reloc::Static &&
 519       TM.getTargetData()->getPointerSize() == 32)
 520     SixteenByteConstantSection =   // .literal16
 521       getContext().getMachOSection("__TEXT", "__literal16",
 522                                    MCSectionMachO::S_16BYTE_LITERALS,
 523                                    SectionKind::getMergeableConst16());
 524
 525   ReadOnlySection  // .const
 526     = getContext().getMachOSection("__TEXT", "__const", 0,
 527                                    SectionKind::getReadOnly());
 528
 529   TextCoalSection
 530     = getContext().getMachOSection("__TEXT", "__textcoal_nt",
 531                                    MCSectionMachO::S_COALESCED |
 532                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 533                                    SectionKind::getText());
 534   ConstTextCoalSection
 535     = getContext().getMachOSection("__TEXT", "__const_coal",
 536                                    MCSectionMachO::S_COALESCED,
 537                                    SectionKind::getReadOnly());
 538   ConstDataSection  // .const_data
 539     = getContext().getMachOSection("__DATA", "__const", 0,
 540                                    SectionKind::getReadOnlyWithRel());
 541   DataCoalSection
 542     = getContext().getMachOSection("__DATA","__datacoal_nt",
 543                                    MCSectionMachO::S_COALESCED,
 544                                    SectionKind::getDataRel());
 545   DataCommonSection
 546     = getContext().getMachOSection("__DATA","__common",
 547                                    MCSectionMachO::S_ZEROFILL,
 548                                    SectionKind::getBSS());
 549   DataBSSSection
 550     = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
 551                                    SectionKind::getBSS());
 552
 553
 554   LazySymbolPointerSection
 555     = getContext().getMachOSection("__DATA", "__la_symbol_ptr",
 556                                    MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
 557                                    SectionKind::getMetadata());
 558   NonLazySymbolPointerSection
 559     = getContext().getMachOSection("__DATA", "__nl_symbol_ptr",
 560                                    MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
 561                                    SectionKind::getMetadata());
 562
 563   if (TM.getRelocationModel() == Reloc::Static) {
 564     StaticCtorSection
 565       = getContext().getMachOSection("__TEXT", "__constructor", 0,
 566                                      SectionKind::getDataRel());
 567     StaticDtorSection
 568       = getContext().getMachOSection("__TEXT", "__destructor", 0,
 569                                      SectionKind::getDataRel());
 570   } else {
 571     StaticCtorSection
 572       = getContext().getMachOSection("__DATA", "__mod_init_func",
 573                                      MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
 574                                      SectionKind::getDataRel());
 575     StaticDtorSection
 576       = getContext().getMachOSection("__DATA", "__mod_term_func",
 577                                      MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
 578                                      SectionKind::getDataRel());
 579   }
 580
 581   // Exception Handling.
 582   LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0,
 583                                              SectionKind::getReadOnlyWithRel());
 584   // Debug Information.
 585   DwarfAbbrevSection =
 586     getContext().getMachOSection("__DWARF", "__debug_abbrev",
 587                                  MCSectionMachO::S_ATTR_DEBUG,
 588                                  SectionKind::getMetadata());
 589   DwarfInfoSection =
 590     getContext().getMachOSection("__DWARF", "__debug_info",
 591                                  MCSectionMachO::S_ATTR_DEBUG,
 592                                  SectionKind::getMetadata());
 593   DwarfLineSection =
 594     getContext().getMachOSection("__DWARF", "__debug_line",
 595                                  MCSectionMachO::S_ATTR_DEBUG,
 596                                  SectionKind::getMetadata());
 597   DwarfFrameSection =
 598     getContext().getMachOSection("__DWARF", "__debug_frame",
 599                                  MCSectionMachO::S_ATTR_DEBUG,
 600                                  SectionKind::getMetadata());
 601   DwarfPubNamesSection =
 602     getContext().getMachOSection("__DWARF", "__debug_pubnames",
 603                                  MCSectionMachO::S_ATTR_DEBUG,
 604                                  SectionKind::getMetadata());
 605   DwarfPubTypesSection =
 606     getContext().getMachOSection("__DWARF", "__debug_pubtypes",
 607                                  MCSectionMachO::S_ATTR_DEBUG,
 608                                  SectionKind::getMetadata());
 609   DwarfStrSection =
 610     getContext().getMachOSection("__DWARF", "__debug_str",
 611                                  MCSectionMachO::S_ATTR_DEBUG,
 612                                  SectionKind::getMetadata());
 613   DwarfLocSection =
 614     getContext().getMachOSection("__DWARF", "__debug_loc",
 615                                  MCSectionMachO::S_ATTR_DEBUG,
 616                                  SectionKind::getMetadata());
 617   DwarfARangesSection =
 618     getContext().getMachOSection("__DWARF", "__debug_aranges",
 619                                  MCSectionMachO::S_ATTR_DEBUG,
 620                                  SectionKind::getMetadata());
 621   DwarfRangesSection =
 622     getContext().getMachOSection("__DWARF", "__debug_ranges",
 623                                  MCSectionMachO::S_ATTR_DEBUG,
 624                                  SectionKind::getMetadata());
 625   DwarfMacroInfoSection =
 626     getContext().getMachOSection("__DWARF", "__debug_macinfo",
 627                                  MCSectionMachO::S_ATTR_DEBUG,
 628                                  SectionKind::getMetadata());
 629   DwarfDebugInlineSection =
 630     getContext().getMachOSection("__DWARF", "__debug_inlined",
 631                                  MCSectionMachO::S_ATTR_DEBUG,
 632                                  SectionKind::getMetadata());
 633
 634   TLSExtraDataSection = TLSTLVSection;
 635 }
 636
 637 const MCSection *TargetLoweringObjectFileMachO::getEHFrameSection() const {
 638   return getContext().getMachOSection("__TEXT", "__eh_frame",
 639                                       MCSectionMachO::S_COALESCED |
 640                                       MCSectionMachO::S_ATTR_NO_TOC |
 641                                       MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
 642                                       MCSectionMachO::S_ATTR_LIVE_SUPPORT,
 643                                       SectionKind::getReadOnly());
 644 }
 645
 646 const MCSection *TargetLoweringObjectFileMachO::
 647 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 648                          Mangler *Mang, const TargetMachine &TM) const {
 649   // Parse the section specifier and create it if valid.
 650   StringRef Segment, Section;
 651   unsigned TAA, StubSize;
 652   std::string ErrorCode =
 653     MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
 654                                           TAA, StubSize);
 655   if (!ErrorCode.empty()) {
 656     // If invalid, report the error with report_fatal_error.
 657     report_fatal_error("Global variable '" + GV->getNameStr() +
 658                       "' has an invalid section specifier '" + GV->getSection()+
 659                       "': " + ErrorCode + ".");
 660     // Fall back to dropping it into the data section.
 661     return DataSection;
 662   }
 663
 664   // Get the section.
 665   const MCSectionMachO *S =
 666     getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
 667
 668   // Okay, now that we got the section, verify that the TAA & StubSize agree.
 669   // If the user declared multiple globals with different section flags, we need
 670   // to reject it here.
 671   if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
 672     // If invalid, report the error with report_fatal_error.
 673     report_fatal_error("Global variable '" + GV->getNameStr() +
 674                       "' section type or attributes does not match previous"
 675                       " section specifier");
 676   }
 677
 678   return S;
 679 }
 680
 681 const MCSection *TargetLoweringObjectFileMachO::
 682 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 683                        Mangler *Mang, const TargetMachine &TM) const {
 684
 685   // Handle thread local data.
 686   if (Kind.isThreadBSS()) return TLSBSSSection;
 687   if (Kind.isThreadData()) return TLSDataSection;
 688
 689   if (Kind.isText())
 690     return GV->isWeakForLinker() ? TextCoalSection : TextSection;
 691
 692   // If this is weak/linkonce, put this in a coalescable section, either in text
 693   // or data depending on if it is writable.
 694   if (GV->isWeakForLinker()) {
 695     if (Kind.isReadOnly())
 696       return ConstTextCoalSection;
 697     return DataCoalSection;
 698   }
 699
 700   // FIXME: Alignment check should be handled by section classifier.
 701   if (Kind.isMergeable1ByteCString() &&
 702       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
 703     return CStringSection;
 704
 705   // Do not put 16-bit arrays in the UString section if they have an
 706   // externally visible label, this runs into issues with certain linker
 707   // versions.
 708   if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
 709       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
 710     return UStringSection;
 711
 712   if (Kind.isMergeableConst()) {
 713     if (Kind.isMergeableConst4())
 714       return FourByteConstantSection;
 715     if (Kind.isMergeableConst8())
 716       return EightByteConstantSection;
 717     if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 718       return SixteenByteConstantSection;
 719   }
 720
 721   // Otherwise, if it is readonly, but not something we can specially optimize,
 722   // just drop it in .const.
 723   if (Kind.isReadOnly())
 724     return ReadOnlySection;
 725
 726   // If this is marked const, put it into a const section.  But if the dynamic
 727   // linker needs to write to it, put it in the data segment.
 728   if (Kind.isReadOnlyWithRel())
 729     return ConstDataSection;
 730
 731   // Put zero initialized globals with strong external linkage in the
 732   // DATA, __common section with the .zerofill directive.
 733   if (Kind.isBSSExtern())
 734     return DataCommonSection;
 735
 736   // Put zero initialized globals with local linkage in __DATA,__bss directive
 737   // with the .zerofill directive (aka .lcomm).
 738   if (Kind.isBSSLocal())
 739     return DataBSSSection;
 740
 741   // Otherwise, just drop the variable in the normal data section.
 742   return DataSection;
 743 }
 744
 745 const MCSection *
 746 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
 747   // If this constant requires a relocation, we have to put it in the data
 748   // segment, not in the text segment.
 749   if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
 750     return ConstDataSection;
 751
 752   if (Kind.isMergeableConst4())
 753     return FourByteConstantSection;
 754   if (Kind.isMergeableConst8())
 755     return EightByteConstantSection;
 756   if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 757     return SixteenByteConstantSection;
 758   return ReadOnlySection;  // .const
 759 }
 760
 761 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
 762 /// not to emit the UsedDirective for some symbols in llvm.used.
 763 // FIXME: REMOVE this (rdar://7071300)
 764 bool TargetLoweringObjectFileMachO::
 765 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
 766   /// On Darwin, internally linked data beginning with "L" or "l" does not have
 767   /// the directive emitted (this occurs in ObjC metadata).
 768   if (!GV) return false;
 769
 770   // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
 771   if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
 772     // FIXME: ObjC metadata is currently emitted as internal symbols that have
 773     // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
 774     // this horrible hack can go away.
 775     MCSymbol *Sym = Mang->getSymbol(GV);
 776     if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
 777       return false;
 778   }
 779
 780   return true;
 781 }
 782
 783 const MCExpr *TargetLoweringObjectFileMachO::
 784 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
 785                                MachineModuleInfo *MMI, unsigned Encoding,
 786                                MCStreamer &Streamer) const {
 787   // The mach-o version of this method defaults to returning a stub reference.
 788
 789   if (Encoding & DW_EH_PE_indirect) {
 790     MachineModuleInfoMachO &MachOMMI =
 791       MMI->getObjFileInfo<MachineModuleInfoMachO>();
 792
 793     SmallString<128> Name;
 794     Mang->getNameWithPrefix(Name, GV, true);
 795     Name += "$non_lazy_ptr";
 796
 797     // Add information about the stub reference to MachOMMI so that the stub
 798     // gets emitted by the asmprinter.
 799     MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
 800     MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
 801     if (StubSym.getPointer() == 0) {
 802       MCSymbol *Sym = Mang->getSymbol(GV);
 803       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
 804     }
 805
 806     return TargetLoweringObjectFile::
 807       getExprForDwarfReference(SSym, Mang, MMI,
 808                                Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
 809   }
 810
 811   return TargetLoweringObjectFile::
 812     getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
 813 }
 814
 815 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const {
 816   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
 817 }
 818
 819 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const {
 820   return DW_EH_PE_pcrel;
 821 }
 822
 823 unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const {
 824   return DW_EH_PE_pcrel;
 825 }
 826
 827 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const {
 828   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
 829 }
 830
 831 //===----------------------------------------------------------------------===//
 832 //                                  COFF
 833 //===----------------------------------------------------------------------===//
 834
 835 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
 836                                               const TargetMachine &TM) {
 837   TargetLoweringObjectFile::Initialize(Ctx, TM);
 838   TextSection =
 839     getContext().getCOFFSection(".text",
 840                                 COFF::IMAGE_SCN_CNT_CODE |
 841                                 COFF::IMAGE_SCN_MEM_EXECUTE |
 842                                 COFF::IMAGE_SCN_MEM_READ,
 843                                 SectionKind::getText());
 844   DataSection =
 845     getContext().getCOFFSection(".data",
 846                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 847                                 COFF::IMAGE_SCN_MEM_READ |
 848                                 COFF::IMAGE_SCN_MEM_WRITE,
 849                                 SectionKind::getDataRel());
 850   ReadOnlySection =
 851     getContext().getCOFFSection(".rdata",
 852                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 853                                 COFF::IMAGE_SCN_MEM_READ,
 854                                 SectionKind::getReadOnly());
 855   StaticCtorSection =
 856     getContext().getCOFFSection(".ctors",
 857                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 858                                 COFF::IMAGE_SCN_MEM_READ |
 859                                 COFF::IMAGE_SCN_MEM_WRITE,
 860                                 SectionKind::getDataRel());
 861   StaticDtorSection =
 862     getContext().getCOFFSection(".dtors",
 863                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 864                                 COFF::IMAGE_SCN_MEM_READ |
 865                                 COFF::IMAGE_SCN_MEM_WRITE,
 866                                 SectionKind::getDataRel());
 867
 868   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
 869   // though it contains relocatable pointers.  In PIC mode, this is probably a
 870   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
 871   // adjusted or this should be a data section.
 872   LSDASection =
 873     getContext().getCOFFSection(".gcc_except_table",
 874                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 875                                 COFF::IMAGE_SCN_MEM_READ,
 876                                 SectionKind::getReadOnly());
 877   // Debug info.
 878   DwarfAbbrevSection =
 879     getContext().getCOFFSection(".debug_abbrev",
 880                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 881                                 COFF::IMAGE_SCN_MEM_READ,
 882                                 SectionKind::getMetadata());
 883   DwarfInfoSection =
 884     getContext().getCOFFSection(".debug_info",
 885                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 886                                 COFF::IMAGE_SCN_MEM_READ,
 887                                 SectionKind::getMetadata());
 888   DwarfLineSection =
 889     getContext().getCOFFSection(".debug_line",
 890                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 891                                 COFF::IMAGE_SCN_MEM_READ,
 892                                 SectionKind::getMetadata());
 893   DwarfFrameSection =
 894     getContext().getCOFFSection(".debug_frame",
 895                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 896                                 COFF::IMAGE_SCN_MEM_READ,
 897                                 SectionKind::getMetadata());
 898   DwarfPubNamesSection =
 899     getContext().getCOFFSection(".debug_pubnames",
 900                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 901                                 COFF::IMAGE_SCN_MEM_READ,
 902                                 SectionKind::getMetadata());
 903   DwarfPubTypesSection =
 904     getContext().getCOFFSection(".debug_pubtypes",
 905                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 906                                 COFF::IMAGE_SCN_MEM_READ,
 907                                 SectionKind::getMetadata());
 908   DwarfStrSection =
 909     getContext().getCOFFSection(".debug_str",
 910                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 911                                 COFF::IMAGE_SCN_MEM_READ,
 912                                 SectionKind::getMetadata());
 913   DwarfLocSection =
 914     getContext().getCOFFSection(".debug_loc",
 915                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 916                                 COFF::IMAGE_SCN_MEM_READ,
 917                                 SectionKind::getMetadata());
 918   DwarfARangesSection =
 919     getContext().getCOFFSection(".debug_aranges",
 920                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 921                                 COFF::IMAGE_SCN_MEM_READ,
 922                                 SectionKind::getMetadata());
 923   DwarfRangesSection =
 924     getContext().getCOFFSection(".debug_ranges",
 925                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 926                                 COFF::IMAGE_SCN_MEM_READ,
 927                                 SectionKind::getMetadata());
 928   DwarfMacroInfoSection =
 929     getContext().getCOFFSection(".debug_macinfo",
 930                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 931                                 COFF::IMAGE_SCN_MEM_READ,
 932                                 SectionKind::getMetadata());
 933
 934   DrectveSection =
 935     getContext().getCOFFSection(".drectve",
 936                                 COFF::IMAGE_SCN_LNK_INFO,
 937                                 SectionKind::getMetadata());
 938 }
 939
 940 const MCSection *TargetLoweringObjectFileCOFF::getEHFrameSection() const {
 941   return getContext().getCOFFSection(".eh_frame",
 942                                      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 943                                      COFF::IMAGE_SCN_MEM_READ |
 944                                      COFF::IMAGE_SCN_MEM_WRITE,
 945                                      SectionKind::getDataRel());
 946 }
 947
 948
 949 static unsigned
 950 getCOFFSectionFlags(SectionKind K) {
 951   unsigned Flags = 0;
 952
 953   if (K.isMetadata())
 954     Flags |=
 955       COFF::IMAGE_SCN_MEM_DISCARDABLE;
 956   else if (K.isText())
 957     Flags |=
 958       COFF::IMAGE_SCN_MEM_EXECUTE |
 959       COFF::IMAGE_SCN_MEM_READ |
 960       COFF::IMAGE_SCN_CNT_CODE;
 961   else if (K.isBSS ())
 962     Flags |=
 963       COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
 964       COFF::IMAGE_SCN_MEM_READ |
 965       COFF::IMAGE_SCN_MEM_WRITE;
 966   else if (K.isReadOnly())
 967     Flags |=
 968       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 969       COFF::IMAGE_SCN_MEM_READ;
 970   else if (K.isWriteable())
 971     Flags |=
 972       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 973       COFF::IMAGE_SCN_MEM_READ |
 974       COFF::IMAGE_SCN_MEM_WRITE;
 975
 976   return Flags;
 977 }
 978
 979 const MCSection *TargetLoweringObjectFileCOFF::
 980 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 981                          Mangler *Mang, const TargetMachine &TM) const {
 982   return getContext().getCOFFSection(GV->getSection(),
 983                                      getCOFFSectionFlags(Kind),
 984                                      Kind);
 985 }
 986
 987 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
 988   if (Kind.isText())
 989     return ".text$";
 990   if (Kind.isBSS ())
 991     return ".bss$";
 992   if (Kind.isWriteable())
 993     return ".data$";
 994   return ".rdata$";
 995 }
 996
 997
 998 const MCSection *TargetLoweringObjectFileCOFF::
 999 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
1000                        Mangler *Mang, const TargetMachine &TM) const {
1001   assert(!Kind.isThreadLocal() && "Doesn't support TLS");
1002
1003   // If this global is linkonce/weak and the target handles this by emitting it
1004   // into a 'uniqued' section name, create and return the section now.
1005   if (GV->isWeakForLinker()) {
1006     const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
1007     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
1008     MCSymbol *Sym = Mang->getSymbol(GV);
1009     Name.append(Sym->getName().begin() + 1, Sym->getName().end());
1010
1011     unsigned Characteristics = getCOFFSectionFlags(Kind);
1012
1013     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
1014
1015     return getContext().getCOFFSection(Name.str(), Characteristics,
1016                           COFF::IMAGE_COMDAT_SELECT_ANY, Kind);
1017   }
1018
1019   if (Kind.isText())
1020     return getTextSection();
1021
1022   return getDataSection();
1023 }
1024