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   // FIXME: Why is this here? Codegen is should not be in the business
 182   // of figuring section flags. If the user wrote section(".eh_frame"),
 183   // we should just pass that to MC which will defer to the assembly
 184   // or use its default if producing an object file.
 185   if (Name.empty() || Name[0] != '.') return K;
 186
 187   // Some lame default implementation based on some magic section names.
 188   if (Name == ".bss" ||
 189       Name.startswith(".bss.") ||
 190       Name.startswith(".gnu.linkonce.b.") ||
 191       Name.startswith(".llvm.linkonce.b.") ||
 192       Name == ".sbss" ||
 193       Name.startswith(".sbss.") ||
 194       Name.startswith(".gnu.linkonce.sb.") ||
 195       Name.startswith(".llvm.linkonce.sb."))
 196     return SectionKind::getBSS();
 197
 198   if (Name == ".tdata" ||
 199       Name.startswith(".tdata.") ||
 200       Name.startswith(".gnu.linkonce.td.") ||
 201       Name.startswith(".llvm.linkonce.td."))
 202     return SectionKind::getThreadData();
 203
 204   if (Name == ".tbss" ||
 205       Name.startswith(".tbss.") ||
 206       Name.startswith(".gnu.linkonce.tb.") ||
 207       Name.startswith(".llvm.linkonce.tb."))
 208     return SectionKind::getThreadBSS();
 209
 210   if (Name == ".eh_frame")
 211     return SectionKind::getDataRel();
 212
 213   return K;
 214 }
 215
 216
 217 static unsigned getELFSectionType(StringRef Name, SectionKind K) {
 218
 219   if (Name == ".init_array")
 220     return ELF::SHT_INIT_ARRAY;
 221
 222   if (Name == ".fini_array")
 223     return ELF::SHT_FINI_ARRAY;
 224
 225   if (Name == ".preinit_array")
 226     return ELF::SHT_PREINIT_ARRAY;
 227
 228   if (K.isBSS() || K.isThreadBSS())
 229     return ELF::SHT_NOBITS;
 230
 231   return ELF::SHT_PROGBITS;
 232 }
 233
 234
 235 static unsigned
 236 getELFSectionFlags(SectionKind K) {
 237   unsigned Flags = 0;
 238
 239   if (!K.isMetadata())
 240     Flags |= ELF::SHF_ALLOC;
 241
 242   if (K.isText())
 243     Flags |= ELF::SHF_EXECINSTR;
 244
 245   if (K.isWriteable())
 246     Flags |= ELF::SHF_WRITE;
 247
 248   if (K.isThreadLocal())
 249     Flags |= ELF::SHF_TLS;
 250
 251   // K.isMergeableConst() is left out to honour PR4650
 252   if (K.isMergeableCString() || K.isMergeableConst4() ||
 253       K.isMergeableConst8() || K.isMergeableConst16())
 254     Flags |= ELF::SHF_MERGE;
 255
 256   if (K.isMergeableCString())
 257     Flags |= ELF::SHF_STRINGS;
 258
 259   return Flags;
 260 }
 261
 262
 263 const MCSection *TargetLoweringObjectFileELF::
 264 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 265                          Mangler *Mang, const TargetMachine &TM) const {
 266   StringRef SectionName = GV->getSection();
 267
 268   // Infer section flags from the section name if we can.
 269   Kind = getELFKindForNamedSection(SectionName, Kind);
 270
 271   return getContext().getELFSection(SectionName,
 272                                     getELFSectionType(SectionName, Kind),
 273                                     getELFSectionFlags(Kind), Kind);
 274 }
 275
 276 /// getSectionPrefixForGlobal - Return the section prefix name used by options
 277 /// FunctionsSections and DataSections.
 278 static const char *getSectionPrefixForGlobal(SectionKind Kind) {
 279   if (Kind.isText())                 return ".text.";
 280   if (Kind.isReadOnly())             return ".rodata.";
 281
 282   if (Kind.isThreadData())           return ".tdata.";
 283   if (Kind.isThreadBSS())            return ".tbss.";
 284
 285   if (Kind.isDataNoRel())            return ".data.";
 286   if (Kind.isDataRelLocal())         return ".data.rel.local.";
 287   if (Kind.isDataRel())              return ".data.rel.";
 288   if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local.";
 289
 290   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 291   return ".data.rel.ro.";
 292 }
 293
 294
 295 const MCSection *TargetLoweringObjectFileELF::
 296 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 297                        Mangler *Mang, const TargetMachine &TM) const {
 298   // If we have -ffunction-section or -fdata-section then we should emit the
 299   // global value to a uniqued section specifically for it.
 300   bool EmitUniquedSection;
 301   if (Kind.isText())
 302     EmitUniquedSection = TM.getFunctionSections();
 303   else
 304     EmitUniquedSection = TM.getDataSections();
 305
 306   // If this global is linkonce/weak and the target handles this by emitting it
 307   // into a 'uniqued' section name, create and return the section now.
 308   if ((GV->isWeakForLinker() || EmitUniquedSection) &&
 309       !Kind.isCommon() && !Kind.isBSS()) {
 310     const char *Prefix;
 311     Prefix = getSectionPrefixForGlobal(Kind);
 312
 313     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
 314     MCSymbol *Sym = Mang->getSymbol(GV);
 315     Name.append(Sym->getName().begin(), Sym->getName().end());
 316     StringRef Group = "";
 317     unsigned Flags = getELFSectionFlags(Kind);
 318     if (GV->isWeakForLinker()) {
 319       Group = Sym->getName();
 320       Flags |= ELF::SHF_GROUP;
 321     }
 322
 323     return getContext().getELFSection(Name.str(),
 324                                       getELFSectionType(Name.str(), Kind),
 325                                       Flags, Kind, 0, Group);
 326   }
 327
 328   if (Kind.isText()) return TextSection;
 329
 330   if (Kind.isMergeable1ByteCString() ||
 331       Kind.isMergeable2ByteCString() ||
 332       Kind.isMergeable4ByteCString()) {
 333
 334     // We also need alignment here.
 335     // FIXME: this is getting the alignment of the character, not the
 336     // alignment of the global!
 337     unsigned Align =
 338       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
 339
 340     const char *SizeSpec = ".rodata.str1.";
 341     if (Kind.isMergeable2ByteCString())
 342       SizeSpec = ".rodata.str2.";
 343     else if (Kind.isMergeable4ByteCString())
 344       SizeSpec = ".rodata.str4.";
 345     else
 346       assert(Kind.isMergeable1ByteCString() && "unknown string width");
 347
 348
 349     std::string Name = SizeSpec + utostr(Align);
 350     return getContext().getELFSection(Name, ELF::SHT_PROGBITS,
 351                                       ELF::SHF_ALLOC |
 352                                       ELF::SHF_MERGE |
 353                                       ELF::SHF_STRINGS,
 354                                       Kind);
 355   }
 356
 357   if (Kind.isMergeableConst()) {
 358     if (Kind.isMergeableConst4() && MergeableConst4Section)
 359       return MergeableConst4Section;
 360     if (Kind.isMergeableConst8() && MergeableConst8Section)
 361       return MergeableConst8Section;
 362     if (Kind.isMergeableConst16() && MergeableConst16Section)
 363       return MergeableConst16Section;
 364     return ReadOnlySection;  // .const
 365   }
 366
 367   if (Kind.isReadOnly())             return ReadOnlySection;
 368
 369   if (Kind.isThreadData())           return TLSDataSection;
 370   if (Kind.isThreadBSS())            return TLSBSSSection;
 371
 372   // Note: we claim that common symbols are put in BSSSection, but they are
 373   // really emitted with the magic .comm directive, which creates a symbol table
 374   // entry but not a section.
 375   if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
 376
 377   if (Kind.isDataNoRel())            return DataSection;
 378   if (Kind.isDataRelLocal())         return DataRelLocalSection;
 379   if (Kind.isDataRel())              return DataRelSection;
 380   if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
 381
 382   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 383   return DataRelROSection;
 384 }
 385
 386 /// getSectionForConstant - Given a mergeable constant with the
 387 /// specified size and relocation information, return a section that it
 388 /// should be placed in.
 389 const MCSection *TargetLoweringObjectFileELF::
 390 getSectionForConstant(SectionKind Kind) const {
 391   if (Kind.isMergeableConst4() && MergeableConst4Section)
 392     return MergeableConst4Section;
 393   if (Kind.isMergeableConst8() && MergeableConst8Section)
 394     return MergeableConst8Section;
 395   if (Kind.isMergeableConst16() && MergeableConst16Section)
 396     return MergeableConst16Section;
 397   if (Kind.isReadOnly())
 398     return ReadOnlySection;
 399
 400   if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
 401   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 402   return DataRelROSection;
 403 }
 404
 405 const MCExpr *TargetLoweringObjectFileELF::
 406 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
 407                                MachineModuleInfo *MMI,
 408                                unsigned Encoding, MCStreamer &Streamer) const {
 409
 410   if (Encoding & dwarf::DW_EH_PE_indirect) {
 411     MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
 412
 413     SmallString<128> Name;
 414     Mang->getNameWithPrefix(Name, GV, true);
 415     Name += ".DW.stub";
 416
 417     // Add information about the stub reference to ELFMMI so that the stub
 418     // gets emitted by the asmprinter.
 419     MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
 420     MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
 421     if (StubSym.getPointer() == 0) {
 422       MCSymbol *Sym = Mang->getSymbol(GV);
 423       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
 424     }
 425
 426     return TargetLoweringObjectFile::
 427       getExprForDwarfReference(SSym, Mang, MMI,
 428                                Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
 429   }
 430
 431   return TargetLoweringObjectFile::
 432     getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
 433 }
 434
 435 //===----------------------------------------------------------------------===//
 436 //                                 MachO
 437 //===----------------------------------------------------------------------===//
 438
 439 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
 440                                                const TargetMachine &TM) {
 441   // _foo.eh symbols are currently always exported so that the linker knows
 442   // about them.  This is not necessary on 10.6 and later, but it
 443   // doesn't hurt anything.
 444   // FIXME: I need to get this from Triple.
 445   IsFunctionEHSymbolGlobal = true;
 446   IsFunctionEHFrameSymbolPrivate = false;
 447   SupportsWeakOmittedEHFrame = false;
 448
 449   Triple T(((LLVMTargetMachine&)TM).getTargetTriple());
 450   if (T.getOS() == Triple::Darwin) {
 451     switch (T.getDarwinMajorNumber()) {
 452     case 7:  // 10.3 Panther.
 453     case 8:  // 10.4 Tiger.
 454       CommDirectiveSupportsAlignment = false;
 455       break;
 456     case 9:   // 10.5 Leopard.
 457     case 10:  // 10.6 SnowLeopard.
 458       break;
 459     }
 460   }
 461
 462   TargetLoweringObjectFile::Initialize(Ctx, TM);
 463
 464   TextSection // .text
 465     = getContext().getMachOSection("__TEXT", "__text",
 466                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 467                                    SectionKind::getText());
 468   DataSection // .data
 469     = getContext().getMachOSection("__DATA", "__data", 0,
 470                                    SectionKind::getDataRel());
 471
 472   TLSDataSection // .tdata
 473     = getContext().getMachOSection("__DATA", "__thread_data",
 474                                    MCSectionMachO::S_THREAD_LOCAL_REGULAR,
 475                                    SectionKind::getDataRel());
 476   TLSBSSSection // .tbss
 477     = getContext().getMachOSection("__DATA", "__thread_bss",
 478                                    MCSectionMachO::S_THREAD_LOCAL_ZEROFILL,
 479                                    SectionKind::getThreadBSS());
 480
 481   // TODO: Verify datarel below.
 482   TLSTLVSection // .tlv
 483     = getContext().getMachOSection("__DATA", "__thread_vars",
 484                                    MCSectionMachO::S_THREAD_LOCAL_VARIABLES,
 485                                    SectionKind::getDataRel());
 486
 487   TLSThreadInitSection
 488     = getContext().getMachOSection("__DATA", "__thread_init",
 489                           MCSectionMachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
 490                           SectionKind::getDataRel());
 491
 492   CStringSection // .cstring
 493     = getContext().getMachOSection("__TEXT", "__cstring",
 494                                    MCSectionMachO::S_CSTRING_LITERALS,
 495                                    SectionKind::getMergeable1ByteCString());
 496   UStringSection
 497     = getContext().getMachOSection("__TEXT","__ustring", 0,
 498                                    SectionKind::getMergeable2ByteCString());
 499   FourByteConstantSection // .literal4
 500     = getContext().getMachOSection("__TEXT", "__literal4",
 501                                    MCSectionMachO::S_4BYTE_LITERALS,
 502                                    SectionKind::getMergeableConst4());
 503   EightByteConstantSection // .literal8
 504     = getContext().getMachOSection("__TEXT", "__literal8",
 505                                    MCSectionMachO::S_8BYTE_LITERALS,
 506                                    SectionKind::getMergeableConst8());
 507
 508   // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
 509   // to using it in -static mode.
 510   SixteenByteConstantSection = 0;
 511   if (TM.getRelocationModel() != Reloc::Static &&
 512       TM.getTargetData()->getPointerSize() == 32)
 513     SixteenByteConstantSection =   // .literal16
 514       getContext().getMachOSection("__TEXT", "__literal16",
 515                                    MCSectionMachO::S_16BYTE_LITERALS,
 516                                    SectionKind::getMergeableConst16());
 517
 518   ReadOnlySection  // .const
 519     = getContext().getMachOSection("__TEXT", "__const", 0,
 520                                    SectionKind::getReadOnly());
 521
 522   TextCoalSection
 523     = getContext().getMachOSection("__TEXT", "__textcoal_nt",
 524                                    MCSectionMachO::S_COALESCED |
 525                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 526                                    SectionKind::getText());
 527   ConstTextCoalSection
 528     = getContext().getMachOSection("__TEXT", "__const_coal",
 529                                    MCSectionMachO::S_COALESCED,
 530                                    SectionKind::getReadOnly());
 531   ConstDataSection  // .const_data
 532     = getContext().getMachOSection("__DATA", "__const", 0,
 533                                    SectionKind::getReadOnlyWithRel());
 534   DataCoalSection
 535     = getContext().getMachOSection("__DATA","__datacoal_nt",
 536                                    MCSectionMachO::S_COALESCED,
 537                                    SectionKind::getDataRel());
 538   DataCommonSection
 539     = getContext().getMachOSection("__DATA","__common",
 540                                    MCSectionMachO::S_ZEROFILL,
 541                                    SectionKind::getBSS());
 542   DataBSSSection
 543     = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
 544                                    SectionKind::getBSS());
 545
 546
 547   LazySymbolPointerSection
 548     = getContext().getMachOSection("__DATA", "__la_symbol_ptr",
 549                                    MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
 550                                    SectionKind::getMetadata());
 551   NonLazySymbolPointerSection
 552     = getContext().getMachOSection("__DATA", "__nl_symbol_ptr",
 553                                    MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
 554                                    SectionKind::getMetadata());
 555
 556   if (TM.getRelocationModel() == Reloc::Static) {
 557     StaticCtorSection
 558       = getContext().getMachOSection("__TEXT", "__constructor", 0,
 559                                      SectionKind::getDataRel());
 560     StaticDtorSection
 561       = getContext().getMachOSection("__TEXT", "__destructor", 0,
 562                                      SectionKind::getDataRel());
 563   } else {
 564     StaticCtorSection
 565       = getContext().getMachOSection("__DATA", "__mod_init_func",
 566                                      MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
 567                                      SectionKind::getDataRel());
 568     StaticDtorSection
 569       = getContext().getMachOSection("__DATA", "__mod_term_func",
 570                                      MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
 571                                      SectionKind::getDataRel());
 572   }
 573
 574   // Exception Handling.
 575   LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0,
 576                                              SectionKind::getReadOnlyWithRel());
 577   // Debug Information.
 578   DwarfAbbrevSection =
 579     getContext().getMachOSection("__DWARF", "__debug_abbrev",
 580                                  MCSectionMachO::S_ATTR_DEBUG,
 581                                  SectionKind::getMetadata());
 582   DwarfInfoSection =
 583     getContext().getMachOSection("__DWARF", "__debug_info",
 584                                  MCSectionMachO::S_ATTR_DEBUG,
 585                                  SectionKind::getMetadata());
 586   DwarfLineSection =
 587     getContext().getMachOSection("__DWARF", "__debug_line",
 588                                  MCSectionMachO::S_ATTR_DEBUG,
 589                                  SectionKind::getMetadata());
 590   DwarfFrameSection =
 591     getContext().getMachOSection("__DWARF", "__debug_frame",
 592                                  MCSectionMachO::S_ATTR_DEBUG,
 593                                  SectionKind::getMetadata());
 594   DwarfPubNamesSection =
 595     getContext().getMachOSection("__DWARF", "__debug_pubnames",
 596                                  MCSectionMachO::S_ATTR_DEBUG,
 597                                  SectionKind::getMetadata());
 598   DwarfPubTypesSection =
 599     getContext().getMachOSection("__DWARF", "__debug_pubtypes",
 600                                  MCSectionMachO::S_ATTR_DEBUG,
 601                                  SectionKind::getMetadata());
 602   DwarfStrSection =
 603     getContext().getMachOSection("__DWARF", "__debug_str",
 604                                  MCSectionMachO::S_ATTR_DEBUG,
 605                                  SectionKind::getMetadata());
 606   DwarfLocSection =
 607     getContext().getMachOSection("__DWARF", "__debug_loc",
 608                                  MCSectionMachO::S_ATTR_DEBUG,
 609                                  SectionKind::getMetadata());
 610   DwarfARangesSection =
 611     getContext().getMachOSection("__DWARF", "__debug_aranges",
 612                                  MCSectionMachO::S_ATTR_DEBUG,
 613                                  SectionKind::getMetadata());
 614   DwarfRangesSection =
 615     getContext().getMachOSection("__DWARF", "__debug_ranges",
 616                                  MCSectionMachO::S_ATTR_DEBUG,
 617                                  SectionKind::getMetadata());
 618   DwarfMacroInfoSection =
 619     getContext().getMachOSection("__DWARF", "__debug_macinfo",
 620                                  MCSectionMachO::S_ATTR_DEBUG,
 621                                  SectionKind::getMetadata());
 622   DwarfDebugInlineSection =
 623     getContext().getMachOSection("__DWARF", "__debug_inlined",
 624                                  MCSectionMachO::S_ATTR_DEBUG,
 625                                  SectionKind::getMetadata());
 626
 627   TLSExtraDataSection = TLSTLVSection;
 628 }
 629
 630 const MCSection *TargetLoweringObjectFileMachO::getEHFrameSection() const {
 631   return getContext().getMachOSection("__TEXT", "__eh_frame",
 632                                       MCSectionMachO::S_COALESCED |
 633                                       MCSectionMachO::S_ATTR_NO_TOC |
 634                                       MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
 635                                       MCSectionMachO::S_ATTR_LIVE_SUPPORT,
 636                                       SectionKind::getReadOnly());
 637 }
 638
 639 const MCSection *TargetLoweringObjectFileMachO::
 640 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 641                          Mangler *Mang, const TargetMachine &TM) const {
 642   // Parse the section specifier and create it if valid.
 643   StringRef Segment, Section;
 644   unsigned TAA = (unsigned)MCSectionMachO::SECTION_ATTRIBUTES, StubSize = 0;
 645   std::string ErrorCode =
 646     MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
 647                                           TAA, StubSize);
 648   if (!ErrorCode.empty()) {
 649     // If invalid, report the error with report_fatal_error.
 650     report_fatal_error("Global variable '" + GV->getNameStr() +
 651                       "' has an invalid section specifier '" + GV->getSection()+
 652                       "': " + ErrorCode + ".");
 653     // Fall back to dropping it into the data section.
 654     return DataSection;
 655   }
 656
 657   bool TAAWasSet = (TAA != MCSectionMachO::SECTION_ATTRIBUTES);
 658   if (!TAAWasSet)
 659     TAA = 0;      // Sensible default if this is a new section.
 660
 661   // Get the section.
 662   const MCSectionMachO *S =
 663     getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
 664
 665   // If TAA wasn't set by ParseSectionSpecifier() above,
 666   // use the value returned by getMachOSection() as a default.
 667   if (!TAAWasSet)
 668     TAA = S->getTypeAndAttributes();
 669
 670   // Okay, now that we got the section, verify that the TAA & StubSize agree.
 671   // If the user declared multiple globals with different section flags, we need
 672   // to reject it here.
 673   if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
 674     // If invalid, report the error with report_fatal_error.
 675     report_fatal_error("Global variable '" + GV->getNameStr() +
 676                       "' section type or attributes does not match previous"
 677                       " section specifier");
 678   }
 679
 680   return S;
 681 }
 682
 683 const MCSection *TargetLoweringObjectFileMachO::
 684 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 685                        Mangler *Mang, const TargetMachine &TM) const {
 686
 687   // Handle thread local data.
 688   if (Kind.isThreadBSS()) return TLSBSSSection;
 689   if (Kind.isThreadData()) return TLSDataSection;
 690
 691   if (Kind.isText())
 692     return GV->isWeakForLinker() ? TextCoalSection : TextSection;
 693
 694   // If this is weak/linkonce, put this in a coalescable section, either in text
 695   // or data depending on if it is writable.
 696   if (GV->isWeakForLinker()) {
 697     if (Kind.isReadOnly())
 698       return ConstTextCoalSection;
 699     return DataCoalSection;
 700   }
 701
 702   // FIXME: Alignment check should be handled by section classifier.
 703   if (Kind.isMergeable1ByteCString() &&
 704       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
 705     return CStringSection;
 706
 707   // Do not put 16-bit arrays in the UString section if they have an
 708   // externally visible label, this runs into issues with certain linker
 709   // versions.
 710   if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
 711       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
 712     return UStringSection;
 713
 714   if (Kind.isMergeableConst()) {
 715     if (Kind.isMergeableConst4())
 716       return FourByteConstantSection;
 717     if (Kind.isMergeableConst8())
 718       return EightByteConstantSection;
 719     if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 720       return SixteenByteConstantSection;
 721   }
 722
 723   // Otherwise, if it is readonly, but not something we can specially optimize,
 724   // just drop it in .const.
 725   if (Kind.isReadOnly())
 726     return ReadOnlySection;
 727
 728   // If this is marked const, put it into a const section.  But if the dynamic
 729   // linker needs to write to it, put it in the data segment.
 730   if (Kind.isReadOnlyWithRel())
 731     return ConstDataSection;
 732
 733   // Put zero initialized globals with strong external linkage in the
 734   // DATA, __common section with the .zerofill directive.
 735   if (Kind.isBSSExtern())
 736     return DataCommonSection;
 737
 738   // Put zero initialized globals with local linkage in __DATA,__bss directive
 739   // with the .zerofill directive (aka .lcomm).
 740   if (Kind.isBSSLocal())
 741     return DataBSSSection;
 742
 743   // Otherwise, just drop the variable in the normal data section.
 744   return DataSection;
 745 }
 746
 747 const MCSection *
 748 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
 749   // If this constant requires a relocation, we have to put it in the data
 750   // segment, not in the text segment.
 751   if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
 752     return ConstDataSection;
 753
 754   if (Kind.isMergeableConst4())
 755     return FourByteConstantSection;
 756   if (Kind.isMergeableConst8())
 757     return EightByteConstantSection;
 758   if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 759     return SixteenByteConstantSection;
 760   return ReadOnlySection;  // .const
 761 }
 762
 763 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
 764 /// not to emit the UsedDirective for some symbols in llvm.used.
 765 // FIXME: REMOVE this (rdar://7071300)
 766 bool TargetLoweringObjectFileMachO::
 767 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
 768   /// On Darwin, internally linked data beginning with "L" or "l" does not have
 769   /// the directive emitted (this occurs in ObjC metadata).
 770   if (!GV) return false;
 771
 772   // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
 773   if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
 774     // FIXME: ObjC metadata is currently emitted as internal symbols that have
 775     // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
 776     // this horrible hack can go away.
 777     MCSymbol *Sym = Mang->getSymbol(GV);
 778     if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
 779       return false;
 780   }
 781
 782   return true;
 783 }
 784
 785 const MCExpr *TargetLoweringObjectFileMachO::
 786 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
 787                                MachineModuleInfo *MMI, unsigned Encoding,
 788                                MCStreamer &Streamer) const {
 789   // The mach-o version of this method defaults to returning a stub reference.
 790
 791   if (Encoding & DW_EH_PE_indirect) {
 792     MachineModuleInfoMachO &MachOMMI =
 793       MMI->getObjFileInfo<MachineModuleInfoMachO>();
 794
 795     SmallString<128> Name;
 796     Mang->getNameWithPrefix(Name, GV, true);
 797     Name += "$non_lazy_ptr";
 798
 799     // Add information about the stub reference to MachOMMI so that the stub
 800     // gets emitted by the asmprinter.
 801     MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
 802     MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
 803     if (StubSym.getPointer() == 0) {
 804       MCSymbol *Sym = Mang->getSymbol(GV);
 805       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
 806     }
 807
 808     return TargetLoweringObjectFile::
 809       getExprForDwarfReference(SSym, Mang, MMI,
 810                                Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
 811   }
 812
 813   return TargetLoweringObjectFile::
 814     getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
 815 }
 816
 817 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const {
 818   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
 819 }
 820
 821 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const {
 822   return DW_EH_PE_pcrel;
 823 }
 824
 825 unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const {
 826   return DW_EH_PE_pcrel;
 827 }
 828
 829 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const {
 830   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
 831 }
 832
 833 //===----------------------------------------------------------------------===//
 834 //                                  COFF
 835 //===----------------------------------------------------------------------===//
 836
 837 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
 838                                               const TargetMachine &TM) {
 839   TargetLoweringObjectFile::Initialize(Ctx, TM);
 840   TextSection =
 841     getContext().getCOFFSection(".text",
 842                                 COFF::IMAGE_SCN_CNT_CODE |
 843                                 COFF::IMAGE_SCN_MEM_EXECUTE |
 844                                 COFF::IMAGE_SCN_MEM_READ,
 845                                 SectionKind::getText());
 846   DataSection =
 847     getContext().getCOFFSection(".data",
 848                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 849                                 COFF::IMAGE_SCN_MEM_READ |
 850                                 COFF::IMAGE_SCN_MEM_WRITE,
 851                                 SectionKind::getDataRel());
 852   ReadOnlySection =
 853     getContext().getCOFFSection(".rdata",
 854                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 855                                 COFF::IMAGE_SCN_MEM_READ,
 856                                 SectionKind::getReadOnly());
 857   StaticCtorSection =
 858     getContext().getCOFFSection(".ctors",
 859                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 860                                 COFF::IMAGE_SCN_MEM_READ |
 861                                 COFF::IMAGE_SCN_MEM_WRITE,
 862                                 SectionKind::getDataRel());
 863   StaticDtorSection =
 864     getContext().getCOFFSection(".dtors",
 865                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 866                                 COFF::IMAGE_SCN_MEM_READ |
 867                                 COFF::IMAGE_SCN_MEM_WRITE,
 868                                 SectionKind::getDataRel());
 869
 870   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
 871   // though it contains relocatable pointers.  In PIC mode, this is probably a
 872   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
 873   // adjusted or this should be a data section.
 874   LSDASection =
 875     getContext().getCOFFSection(".gcc_except_table",
 876                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 877                                 COFF::IMAGE_SCN_MEM_READ,
 878                                 SectionKind::getReadOnly());
 879   // Debug info.
 880   DwarfAbbrevSection =
 881     getContext().getCOFFSection(".debug_abbrev",
 882                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 883                                 COFF::IMAGE_SCN_MEM_READ,
 884                                 SectionKind::getMetadata());
 885   DwarfInfoSection =
 886     getContext().getCOFFSection(".debug_info",
 887                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 888                                 COFF::IMAGE_SCN_MEM_READ,
 889                                 SectionKind::getMetadata());
 890   DwarfLineSection =
 891     getContext().getCOFFSection(".debug_line",
 892                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 893                                 COFF::IMAGE_SCN_MEM_READ,
 894                                 SectionKind::getMetadata());
 895   DwarfFrameSection =
 896     getContext().getCOFFSection(".debug_frame",
 897                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 898                                 COFF::IMAGE_SCN_MEM_READ,
 899                                 SectionKind::getMetadata());
 900   DwarfPubNamesSection =
 901     getContext().getCOFFSection(".debug_pubnames",
 902                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 903                                 COFF::IMAGE_SCN_MEM_READ,
 904                                 SectionKind::getMetadata());
 905   DwarfPubTypesSection =
 906     getContext().getCOFFSection(".debug_pubtypes",
 907                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 908                                 COFF::IMAGE_SCN_MEM_READ,
 909                                 SectionKind::getMetadata());
 910   DwarfStrSection =
 911     getContext().getCOFFSection(".debug_str",
 912                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 913                                 COFF::IMAGE_SCN_MEM_READ,
 914                                 SectionKind::getMetadata());
 915   DwarfLocSection =
 916     getContext().getCOFFSection(".debug_loc",
 917                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 918                                 COFF::IMAGE_SCN_MEM_READ,
 919                                 SectionKind::getMetadata());
 920   DwarfARangesSection =
 921     getContext().getCOFFSection(".debug_aranges",
 922                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 923                                 COFF::IMAGE_SCN_MEM_READ,
 924                                 SectionKind::getMetadata());
 925   DwarfRangesSection =
 926     getContext().getCOFFSection(".debug_ranges",
 927                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 928                                 COFF::IMAGE_SCN_MEM_READ,
 929                                 SectionKind::getMetadata());
 930   DwarfMacroInfoSection =
 931     getContext().getCOFFSection(".debug_macinfo",
 932                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 933                                 COFF::IMAGE_SCN_MEM_READ,
 934                                 SectionKind::getMetadata());
 935
 936   DrectveSection =
 937     getContext().getCOFFSection(".drectve",
 938                                 COFF::IMAGE_SCN_LNK_INFO,
 939                                 SectionKind::getMetadata());
 940 }
 941
 942 const MCSection *TargetLoweringObjectFileCOFF::getEHFrameSection() const {
 943   return getContext().getCOFFSection(".eh_frame",
 944                                      COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 945                                      COFF::IMAGE_SCN_MEM_READ |
 946                                      COFF::IMAGE_SCN_MEM_WRITE,
 947                                      SectionKind::getDataRel());
 948 }
 949
 950
 951 static unsigned
 952 getCOFFSectionFlags(SectionKind K) {
 953   unsigned Flags = 0;
 954
 955   if (K.isMetadata())
 956     Flags |=
 957       COFF::IMAGE_SCN_MEM_DISCARDABLE;
 958   else if (K.isText())
 959     Flags |=
 960       COFF::IMAGE_SCN_MEM_EXECUTE |
 961       COFF::IMAGE_SCN_MEM_READ |
 962       COFF::IMAGE_SCN_CNT_CODE;
 963   else if (K.isBSS ())
 964     Flags |=
 965       COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
 966       COFF::IMAGE_SCN_MEM_READ |
 967       COFF::IMAGE_SCN_MEM_WRITE;
 968   else if (K.isReadOnly())
 969     Flags |=
 970       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 971       COFF::IMAGE_SCN_MEM_READ;
 972   else if (K.isWriteable())
 973     Flags |=
 974       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 975       COFF::IMAGE_SCN_MEM_READ |
 976       COFF::IMAGE_SCN_MEM_WRITE;
 977
 978   return Flags;
 979 }
 980
 981 const MCSection *TargetLoweringObjectFileCOFF::
 982 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 983                          Mangler *Mang, const TargetMachine &TM) const {
 984   return getContext().getCOFFSection(GV->getSection(),
 985                                      getCOFFSectionFlags(Kind),
 986                                      Kind);
 987 }
 988
 989 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
 990   if (Kind.isText())
 991     return ".text$";
 992   if (Kind.isBSS ())
 993     return ".bss$";
 994   if (Kind.isWriteable())
 995     return ".data$";
 996   return ".rdata$";
 997 }
 998
 999
1000 const MCSection *TargetLoweringObjectFileCOFF::
1001 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
1002                        Mangler *Mang, const TargetMachine &TM) const {
1003   assert(!Kind.isThreadLocal() && "Doesn't support TLS");
1004
1005   // If this global is linkonce/weak and the target handles this by emitting it
1006   // into a 'uniqued' section name, create and return the section now.
1007   if (GV->isWeakForLinker()) {
1008     const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
1009     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
1010     MCSymbol *Sym = Mang->getSymbol(GV);
1011     Name.append(Sym->getName().begin() + 1, Sym->getName().end());
1012
1013     unsigned Characteristics = getCOFFSectionFlags(Kind);
1014
1015     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
1016
1017     return getContext().getCOFFSection(Name.str(), Characteristics,
1018                           COFF::IMAGE_COMDAT_SELECT_ANY, Kind);
1019   }
1020
1021   if (Kind.isText())
1022     return getTextSection();
1023
1024   return getDataSection();
1025 }
1026