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     unsigned MajNum = T.getDarwinMajorNumber();
 445     if (MajNum == 7 || MajNum == 8) // 10.3 Panther, 10.4 Tiger
 446       CommDirectiveSupportsAlignment = false;
 447     if (MajNum > 9)                 // 10.6 SnowLeopard
 448       IsFunctionEHSymbolGlobal = false;
 449   }
 450
 451   TargetLoweringObjectFile::Initialize(Ctx, TM);
 452
 453   TextSection // .text
 454     = getContext().getMachOSection("__TEXT", "__text",
 455                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 456                                    SectionKind::getText());
 457   DataSection // .data
 458     = getContext().getMachOSection("__DATA", "__data", 0,
 459                                    SectionKind::getDataRel());
 460
 461   TLSDataSection // .tdata
 462     = getContext().getMachOSection("__DATA", "__thread_data",
 463                                    MCSectionMachO::S_THREAD_LOCAL_REGULAR,
 464                                    SectionKind::getDataRel());
 465   TLSBSSSection // .tbss
 466     = getContext().getMachOSection("__DATA", "__thread_bss",
 467                                    MCSectionMachO::S_THREAD_LOCAL_ZEROFILL,
 468                                    SectionKind::getThreadBSS());
 469
 470   // TODO: Verify datarel below.
 471   TLSTLVSection // .tlv
 472     = getContext().getMachOSection("__DATA", "__thread_vars",
 473                                    MCSectionMachO::S_THREAD_LOCAL_VARIABLES,
 474                                    SectionKind::getDataRel());
 475
 476   TLSThreadInitSection
 477     = getContext().getMachOSection("__DATA", "__thread_init",
 478                           MCSectionMachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
 479                           SectionKind::getDataRel());
 480
 481   CStringSection // .cstring
 482     = getContext().getMachOSection("__TEXT", "__cstring",
 483                                    MCSectionMachO::S_CSTRING_LITERALS,
 484                                    SectionKind::getMergeable1ByteCString());
 485   UStringSection
 486     = getContext().getMachOSection("__TEXT","__ustring", 0,
 487                                    SectionKind::getMergeable2ByteCString());
 488   FourByteConstantSection // .literal4
 489     = getContext().getMachOSection("__TEXT", "__literal4",
 490                                    MCSectionMachO::S_4BYTE_LITERALS,
 491                                    SectionKind::getMergeableConst4());
 492   EightByteConstantSection // .literal8
 493     = getContext().getMachOSection("__TEXT", "__literal8",
 494                                    MCSectionMachO::S_8BYTE_LITERALS,
 495                                    SectionKind::getMergeableConst8());
 496
 497   // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
 498   // to using it in -static mode.
 499   SixteenByteConstantSection = 0;
 500   if (TM.getRelocationModel() != Reloc::Static &&
 501       TM.getTargetData()->getPointerSize() == 32)
 502     SixteenByteConstantSection =   // .literal16
 503       getContext().getMachOSection("__TEXT", "__literal16",
 504                                    MCSectionMachO::S_16BYTE_LITERALS,
 505                                    SectionKind::getMergeableConst16());
 506
 507   ReadOnlySection  // .const
 508     = getContext().getMachOSection("__TEXT", "__const", 0,
 509                                    SectionKind::getReadOnly());
 510
 511   TextCoalSection
 512     = getContext().getMachOSection("__TEXT", "__textcoal_nt",
 513                                    MCSectionMachO::S_COALESCED |
 514                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 515                                    SectionKind::getText());
 516   ConstTextCoalSection
 517     = getContext().getMachOSection("__TEXT", "__const_coal",
 518                                    MCSectionMachO::S_COALESCED,
 519                                    SectionKind::getReadOnly());
 520   ConstDataSection  // .const_data
 521     = getContext().getMachOSection("__DATA", "__const", 0,
 522                                    SectionKind::getReadOnlyWithRel());
 523   DataCoalSection
 524     = getContext().getMachOSection("__DATA","__datacoal_nt",
 525                                    MCSectionMachO::S_COALESCED,
 526                                    SectionKind::getDataRel());
 527   DataCommonSection
 528     = getContext().getMachOSection("__DATA","__common",
 529                                    MCSectionMachO::S_ZEROFILL,
 530                                    SectionKind::getBSS());
 531   DataBSSSection
 532     = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
 533                                    SectionKind::getBSS());
 534
 535
 536   LazySymbolPointerSection
 537     = getContext().getMachOSection("__DATA", "__la_symbol_ptr",
 538                                    MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
 539                                    SectionKind::getMetadata());
 540   NonLazySymbolPointerSection
 541     = getContext().getMachOSection("__DATA", "__nl_symbol_ptr",
 542                                    MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
 543                                    SectionKind::getMetadata());
 544
 545   if (TM.getRelocationModel() == Reloc::Static) {
 546     StaticCtorSection
 547       = getContext().getMachOSection("__TEXT", "__constructor", 0,
 548                                      SectionKind::getDataRel());
 549     StaticDtorSection
 550       = getContext().getMachOSection("__TEXT", "__destructor", 0,
 551                                      SectionKind::getDataRel());
 552   } else {
 553     StaticCtorSection
 554       = getContext().getMachOSection("__DATA", "__mod_init_func",
 555                                      MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
 556                                      SectionKind::getDataRel());
 557     StaticDtorSection
 558       = getContext().getMachOSection("__DATA", "__mod_term_func",
 559                                      MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
 560                                      SectionKind::getDataRel());
 561   }
 562
 563   // Exception Handling.
 564   LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0,
 565                                              SectionKind::getReadOnlyWithRel());
 566   // Debug Information.
 567   DwarfAbbrevSection =
 568     getContext().getMachOSection("__DWARF", "__debug_abbrev",
 569                                  MCSectionMachO::S_ATTR_DEBUG,
 570                                  SectionKind::getMetadata());
 571   DwarfInfoSection =
 572     getContext().getMachOSection("__DWARF", "__debug_info",
 573                                  MCSectionMachO::S_ATTR_DEBUG,
 574                                  SectionKind::getMetadata());
 575   DwarfLineSection =
 576     getContext().getMachOSection("__DWARF", "__debug_line",
 577                                  MCSectionMachO::S_ATTR_DEBUG,
 578                                  SectionKind::getMetadata());
 579   DwarfFrameSection =
 580     getContext().getMachOSection("__DWARF", "__debug_frame",
 581                                  MCSectionMachO::S_ATTR_DEBUG,
 582                                  SectionKind::getMetadata());
 583   DwarfPubNamesSection =
 584     getContext().getMachOSection("__DWARF", "__debug_pubnames",
 585                                  MCSectionMachO::S_ATTR_DEBUG,
 586                                  SectionKind::getMetadata());
 587   DwarfPubTypesSection =
 588     getContext().getMachOSection("__DWARF", "__debug_pubtypes",
 589                                  MCSectionMachO::S_ATTR_DEBUG,
 590                                  SectionKind::getMetadata());
 591   DwarfStrSection =
 592     getContext().getMachOSection("__DWARF", "__debug_str",
 593                                  MCSectionMachO::S_ATTR_DEBUG,
 594                                  SectionKind::getMetadata());
 595   DwarfLocSection =
 596     getContext().getMachOSection("__DWARF", "__debug_loc",
 597                                  MCSectionMachO::S_ATTR_DEBUG,
 598                                  SectionKind::getMetadata());
 599   DwarfARangesSection =
 600     getContext().getMachOSection("__DWARF", "__debug_aranges",
 601                                  MCSectionMachO::S_ATTR_DEBUG,
 602                                  SectionKind::getMetadata());
 603   DwarfRangesSection =
 604     getContext().getMachOSection("__DWARF", "__debug_ranges",
 605                                  MCSectionMachO::S_ATTR_DEBUG,
 606                                  SectionKind::getMetadata());
 607   DwarfMacroInfoSection =
 608     getContext().getMachOSection("__DWARF", "__debug_macinfo",
 609                                  MCSectionMachO::S_ATTR_DEBUG,
 610                                  SectionKind::getMetadata());
 611   DwarfDebugInlineSection =
 612     getContext().getMachOSection("__DWARF", "__debug_inlined",
 613                                  MCSectionMachO::S_ATTR_DEBUG,
 614                                  SectionKind::getMetadata());
 615
 616   TLSExtraDataSection = TLSTLVSection;
 617 }
 618
 619 const MCSection *TargetLoweringObjectFileMachO::getEHFrameSection() const {
 620   return getContext().getMachOSection("__TEXT", "__eh_frame",
 621                                       MCSectionMachO::S_COALESCED |
 622                                       MCSectionMachO::S_ATTR_NO_TOC |
 623                                       MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
 624                                       MCSectionMachO::S_ATTR_LIVE_SUPPORT,
 625                                       SectionKind::getReadOnly());
 626 }
 627
 628 const MCSection *TargetLoweringObjectFileMachO::
 629 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 630                          Mangler *Mang, const TargetMachine &TM) const {
 631   // Parse the section specifier and create it if valid.
 632   StringRef Segment, Section;
 633   unsigned TAA = (unsigned)MCSectionMachO::SECTION_ATTRIBUTES, StubSize = 0;
 634   std::string ErrorCode =
 635     MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
 636                                           TAA, StubSize);
 637   if (!ErrorCode.empty()) {
 638     // If invalid, report the error with report_fatal_error.
 639     report_fatal_error("Global variable '" + GV->getNameStr() +
 640                       "' has an invalid section specifier '" + GV->getSection()+
 641                       "': " + ErrorCode + ".");
 642     // Fall back to dropping it into the data section.
 643     return DataSection;
 644   }
 645
 646   bool TAAWasSet = (TAA != MCSectionMachO::SECTION_ATTRIBUTES);
 647   if (!TAAWasSet)
 648     TAA = 0;      // Sensible default if this is a new section.
 649
 650   // Get the section.
 651   const MCSectionMachO *S =
 652     getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
 653
 654   // If TAA wasn't set by ParseSectionSpecifier() above,
 655   // use the value returned by getMachOSection() as a default.
 656   if (!TAAWasSet)
 657     TAA = S->getTypeAndAttributes();
 658
 659   // Okay, now that we got the section, verify that the TAA & StubSize agree.
 660   // If the user declared multiple globals with different section flags, we need
 661   // to reject it here.
 662   if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
 663     // If invalid, report the error with report_fatal_error.
 664     report_fatal_error("Global variable '" + GV->getNameStr() +
 665                       "' section type or attributes does not match previous"
 666                       " section specifier");
 667   }
 668
 669   return S;
 670 }
 671
 672 const MCSection *TargetLoweringObjectFileMachO::
 673 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 674                        Mangler *Mang, const TargetMachine &TM) const {
 675
 676   // Handle thread local data.
 677   if (Kind.isThreadBSS()) return TLSBSSSection;
 678   if (Kind.isThreadData()) return TLSDataSection;
 679
 680   if (Kind.isText())
 681     return GV->isWeakForLinker() ? TextCoalSection : TextSection;
 682
 683   // If this is weak/linkonce, put this in a coalescable section, either in text
 684   // or data depending on if it is writable.
 685   if (GV->isWeakForLinker()) {
 686     if (Kind.isReadOnly())
 687       return ConstTextCoalSection;
 688     return DataCoalSection;
 689   }
 690
 691   // FIXME: Alignment check should be handled by section classifier.
 692   if (Kind.isMergeable1ByteCString() &&
 693       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
 694     return CStringSection;
 695
 696   // Do not put 16-bit arrays in the UString section if they have an
 697   // externally visible label, this runs into issues with certain linker
 698   // versions.
 699   if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
 700       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
 701     return UStringSection;
 702
 703   if (Kind.isMergeableConst()) {
 704     if (Kind.isMergeableConst4())
 705       return FourByteConstantSection;
 706     if (Kind.isMergeableConst8())
 707       return EightByteConstantSection;
 708     if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 709       return SixteenByteConstantSection;
 710   }
 711
 712   // Otherwise, if it is readonly, but not something we can specially optimize,
 713   // just drop it in .const.
 714   if (Kind.isReadOnly())
 715     return ReadOnlySection;
 716
 717   // If this is marked const, put it into a const section.  But if the dynamic
 718   // linker needs to write to it, put it in the data segment.
 719   if (Kind.isReadOnlyWithRel())
 720     return ConstDataSection;
 721
 722   // Put zero initialized globals with strong external linkage in the
 723   // DATA, __common section with the .zerofill directive.
 724   if (Kind.isBSSExtern())
 725     return DataCommonSection;
 726
 727   // Put zero initialized globals with local linkage in __DATA,__bss directive
 728   // with the .zerofill directive (aka .lcomm).
 729   if (Kind.isBSSLocal())
 730     return DataBSSSection;
 731
 732   // Otherwise, just drop the variable in the normal data section.
 733   return DataSection;
 734 }
 735
 736 const MCSection *
 737 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
 738   // If this constant requires a relocation, we have to put it in the data
 739   // segment, not in the text segment.
 740   if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
 741     return ConstDataSection;
 742
 743   if (Kind.isMergeableConst4())
 744     return FourByteConstantSection;
 745   if (Kind.isMergeableConst8())
 746     return EightByteConstantSection;
 747   if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 748     return SixteenByteConstantSection;
 749   return ReadOnlySection;  // .const
 750 }
 751
 752 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
 753 /// not to emit the UsedDirective for some symbols in llvm.used.
 754 // FIXME: REMOVE this (rdar://7071300)
 755 bool TargetLoweringObjectFileMachO::
 756 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
 757   /// On Darwin, internally linked data beginning with "L" or "l" does not have
 758   /// the directive emitted (this occurs in ObjC metadata).
 759   if (!GV) return false;
 760
 761   // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
 762   if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
 763     // FIXME: ObjC metadata is currently emitted as internal symbols that have
 764     // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
 765     // this horrible hack can go away.
 766     MCSymbol *Sym = Mang->getSymbol(GV);
 767     if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
 768       return false;
 769   }
 770
 771   return true;
 772 }
 773
 774 const MCExpr *TargetLoweringObjectFileMachO::
 775 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
 776                                MachineModuleInfo *MMI, unsigned Encoding,
 777                                MCStreamer &Streamer) const {
 778   // The mach-o version of this method defaults to returning a stub reference.
 779
 780   if (Encoding & DW_EH_PE_indirect) {
 781     MachineModuleInfoMachO &MachOMMI =
 782       MMI->getObjFileInfo<MachineModuleInfoMachO>();
 783
 784     SmallString<128> Name;
 785     Mang->getNameWithPrefix(Name, GV, true);
 786     Name += "$non_lazy_ptr";
 787
 788     // Add information about the stub reference to MachOMMI so that the stub
 789     // gets emitted by the asmprinter.
 790     MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
 791     MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
 792     if (StubSym.getPointer() == 0) {
 793       MCSymbol *Sym = Mang->getSymbol(GV);
 794       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
 795     }
 796
 797     return TargetLoweringObjectFile::
 798       getExprForDwarfReference(SSym, Mang, MMI,
 799                                Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
 800   }
 801
 802   return TargetLoweringObjectFile::
 803     getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
 804 }
 805
 806 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const {
 807   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
 808 }
 809
 810 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const {
 811   return DW_EH_PE_pcrel;
 812 }
 813
 814 unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const {
 815   return DW_EH_PE_pcrel;
 816 }
 817
 818 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const {
 819   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
 820 }
 821
 822 //===----------------------------------------------------------------------===//
 823 //                                  COFF
 824 //===----------------------------------------------------------------------===//
 825
 826 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
 827                                               const TargetMachine &TM) {
 828   TargetLoweringObjectFile::Initialize(Ctx, TM);
 829   TextSection =
 830     getContext().getCOFFSection(".text",
 831                                 COFF::IMAGE_SCN_CNT_CODE |
 832                                 COFF::IMAGE_SCN_MEM_EXECUTE |
 833                                 COFF::IMAGE_SCN_MEM_READ,
 834                                 SectionKind::getText());
 835   DataSection =
 836     getContext().getCOFFSection(".data",
 837                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 838                                 COFF::IMAGE_SCN_MEM_READ |
 839                                 COFF::IMAGE_SCN_MEM_WRITE,
 840                                 SectionKind::getDataRel());
 841   ReadOnlySection =
 842     getContext().getCOFFSection(".rdata",
 843                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 844                                 COFF::IMAGE_SCN_MEM_READ,
 845                                 SectionKind::getReadOnly());
 846   StaticCtorSection =
 847     getContext().getCOFFSection(".ctors",
 848                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 849                                 COFF::IMAGE_SCN_MEM_READ |
 850                                 COFF::IMAGE_SCN_MEM_WRITE,
 851                                 SectionKind::getDataRel());
 852   StaticDtorSection =
 853     getContext().getCOFFSection(".dtors",
 854                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 855                                 COFF::IMAGE_SCN_MEM_READ |
 856                                 COFF::IMAGE_SCN_MEM_WRITE,
 857                                 SectionKind::getDataRel());
 858
 859   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
 860   // though it contains relocatable pointers.  In PIC mode, this is probably a
 861   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
 862   // adjusted or this should be a data section.
 863   LSDASection =
 864     getContext().getCOFFSection(".gcc_except_table",
 865                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 866                                 COFF::IMAGE_SCN_MEM_READ,
 867                                 SectionKind::getReadOnly());
 868   // Debug info.
 869   DwarfAbbrevSection =
 870     getContext().getCOFFSection(".debug_abbrev",
 871                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 872                                 COFF::IMAGE_SCN_MEM_READ,
 873                                 SectionKind::getMetadata());
 874   DwarfInfoSection =
 875     getContext().getCOFFSection(".debug_info",
 876                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 877                                 COFF::IMAGE_SCN_MEM_READ,
 878                                 SectionKind::getMetadata());
 879   DwarfLineSection =
 880     getContext().getCOFFSection(".debug_line",
 881                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 882                                 COFF::IMAGE_SCN_MEM_READ,
 883                                 SectionKind::getMetadata());
 884   DwarfFrameSection =
 885     getContext().getCOFFSection(".debug_frame",
 886                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 887                                 COFF::IMAGE_SCN_MEM_READ,
 888                                 SectionKind::getMetadata());
 889   DwarfPubNamesSection =
 890     getContext().getCOFFSection(".debug_pubnames",
 891                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 892                                 COFF::IMAGE_SCN_MEM_READ,
 893                                 SectionKind::getMetadata());
 894   DwarfPubTypesSection =
 895     getContext().getCOFFSection(".debug_pubtypes",
 896                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 897                                 COFF::IMAGE_SCN_MEM_READ,
 898                                 SectionKind::getMetadata());
 899   DwarfStrSection =
 900     getContext().getCOFFSection(".debug_str",
 901                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 902                                 COFF::IMAGE_SCN_MEM_READ,
 903                                 SectionKind::getMetadata());
 904   DwarfLocSection =
 905     getContext().getCOFFSection(".debug_loc",
 906                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 907                                 COFF::IMAGE_SCN_MEM_READ,
 908                                 SectionKind::getMetadata());
 909   DwarfARangesSection =
 910     getContext().getCOFFSection(".debug_aranges",
 911                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 912                                 COFF::IMAGE_SCN_MEM_READ,
 913                                 SectionKind::getMetadata());
 914   DwarfRangesSection =
 915     getContext().getCOFFSection(".debug_ranges",
 916                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 917                                 COFF::IMAGE_SCN_MEM_READ,
 918                                 SectionKind::getMetadata());
 919   DwarfMacroInfoSection =
 920     getContext().getCOFFSection(".debug_macinfo",
 921                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 922                                 COFF::IMAGE_SCN_MEM_READ,
 923                                 SectionKind::getMetadata());
 924
 925   DrectveSection =
 926     getContext().getCOFFSection(".drectve",
 927                                 COFF::IMAGE_SCN_LNK_INFO,
 928                                 SectionKind::getMetadata());
 929 }
 930
 931 const MCSection *TargetLoweringObjectFileCOFF::getEHFrameSection() const {
 932   return getContext().getCOFFSection(".eh_frame",
 933                                      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 934                                      COFF::IMAGE_SCN_MEM_READ |
 935                                      COFF::IMAGE_SCN_MEM_WRITE,
 936                                      SectionKind::getDataRel());
 937 }
 938
 939
 940 static unsigned
 941 getCOFFSectionFlags(SectionKind K) {
 942   unsigned Flags = 0;
 943
 944   if (K.isMetadata())
 945     Flags |=
 946       COFF::IMAGE_SCN_MEM_DISCARDABLE;
 947   else if (K.isText())
 948     Flags |=
 949       COFF::IMAGE_SCN_MEM_EXECUTE |
 950       COFF::IMAGE_SCN_MEM_READ |
 951       COFF::IMAGE_SCN_CNT_CODE;
 952   else if (K.isBSS ())
 953     Flags |=
 954       COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
 955       COFF::IMAGE_SCN_MEM_READ |
 956       COFF::IMAGE_SCN_MEM_WRITE;
 957   else if (K.isReadOnly())
 958     Flags |=
 959       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 960       COFF::IMAGE_SCN_MEM_READ;
 961   else if (K.isWriteable())
 962     Flags |=
 963       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 964       COFF::IMAGE_SCN_MEM_READ |
 965       COFF::IMAGE_SCN_MEM_WRITE;
 966
 967   return Flags;
 968 }
 969
 970 const MCSection *TargetLoweringObjectFileCOFF::
 971 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 972                          Mangler *Mang, const TargetMachine &TM) const {
 973   return getContext().getCOFFSection(GV->getSection(),
 974                                      getCOFFSectionFlags(Kind),
 975                                      Kind);
 976 }
 977
 978 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
 979   if (Kind.isText())
 980     return ".text$";
 981   if (Kind.isBSS ())
 982     return ".bss$";
 983   if (Kind.isWriteable())
 984     return ".data$";
 985   return ".rdata$";
 986 }
 987
 988
 989 const MCSection *TargetLoweringObjectFileCOFF::
 990 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 991                        Mangler *Mang, const TargetMachine &TM) const {
 992   assert(!Kind.isThreadLocal() && "Doesn't support TLS");
 993
 994   // If this global is linkonce/weak and the target handles this by emitting it
 995   // into a 'uniqued' section name, create and return the section now.
 996   if (GV->isWeakForLinker()) {
 997     const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
 998     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
 999     MCSymbol *Sym = Mang->getSymbol(GV);
1000     Name.append(Sym->getName().begin() + 1, Sym->getName().end());
1001
1002     unsigned Characteristics = getCOFFSectionFlags(Kind);
1003
1004     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
1005
1006     return getContext().getCOFFSection(Name.str(), Characteristics,
1007                           COFF::IMAGE_COMDAT_SELECT_ANY, Kind);
1008   }
1009
1010   if (Kind.isText())
1011     return getTextSection();
1012
1013   return getDataSection();
1014 }
1015