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/ErrorHandling.h"
  33 #include "llvm/Support/raw_ostream.h"
  34 #include "llvm/ADT/SmallString.h"
  35 #include "llvm/ADT/StringExtras.h"
  36 #include "llvm/ADT/Triple.h"
  37 using namespace llvm;
  38 using namespace dwarf;
  39
  40 //===----------------------------------------------------------------------===//
  41 //                                  ELF
  42 //===----------------------------------------------------------------------===//
  43
  44 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
  45                                              const TargetMachine &TM) {
  46   TargetLoweringObjectFile::Initialize(Ctx, TM);
  47
  48   BSSSection =
  49     getContext().getELFSection(".bss", MCSectionELF::SHT_NOBITS,
  50                                MCSectionELF::SHF_WRITE |MCSectionELF::SHF_ALLOC,
  51                                SectionKind::getBSS());
  52
  53   TextSection =
  54     getContext().getELFSection(".text", MCSectionELF::SHT_PROGBITS,
  55                                MCSectionELF::SHF_EXECINSTR |
  56                                MCSectionELF::SHF_ALLOC,
  57                                SectionKind::getText());
  58
  59   DataSection =
  60     getContext().getELFSection(".data", MCSectionELF::SHT_PROGBITS,
  61                                MCSectionELF::SHF_WRITE |MCSectionELF::SHF_ALLOC,
  62                                SectionKind::getDataRel());
  63
  64   ReadOnlySection =
  65     getContext().getELFSection(".rodata", MCSectionELF::SHT_PROGBITS,
  66                                MCSectionELF::SHF_ALLOC,
  67                                SectionKind::getReadOnly());
  68
  69   TLSDataSection =
  70     getContext().getELFSection(".tdata", MCSectionELF::SHT_PROGBITS,
  71                                MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
  72                                MCSectionELF::SHF_WRITE,
  73                                SectionKind::getThreadData());
  74
  75   TLSBSSSection =
  76     getContext().getELFSection(".tbss", MCSectionELF::SHT_NOBITS,
  77                                MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
  78                                MCSectionELF::SHF_WRITE,
  79                                SectionKind::getThreadBSS());
  80
  81   DataRelSection =
  82     getContext().getELFSection(".data.rel", MCSectionELF::SHT_PROGBITS,
  83                                MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
  84                                SectionKind::getDataRel());
  85
  86   DataRelLocalSection =
  87     getContext().getELFSection(".data.rel.local", MCSectionELF::SHT_PROGBITS,
  88                                MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
  89                                SectionKind::getDataRelLocal());
  90
  91   DataRelROSection =
  92     getContext().getELFSection(".data.rel.ro", MCSectionELF::SHT_PROGBITS,
  93                                MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
  94                                SectionKind::getReadOnlyWithRel());
  95
  96   DataRelROLocalSection =
  97     getContext().getELFSection(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS,
  98                                MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
  99                                SectionKind::getReadOnlyWithRelLocal());
 100
 101   MergeableConst4Section =
 102     getContext().getELFSection(".rodata.cst4", MCSectionELF::SHT_PROGBITS,
 103                                MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_MERGE,
 104                                SectionKind::getMergeableConst4());
 105
 106   MergeableConst8Section =
 107     getContext().getELFSection(".rodata.cst8", MCSectionELF::SHT_PROGBITS,
 108                                MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_MERGE,
 109                                SectionKind::getMergeableConst8());
 110
 111   MergeableConst16Section =
 112     getContext().getELFSection(".rodata.cst16", MCSectionELF::SHT_PROGBITS,
 113                                MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_MERGE,
 114                                SectionKind::getMergeableConst16());
 115
 116   StaticCtorSection =
 117     getContext().getELFSection(".ctors", MCSectionELF::SHT_PROGBITS,
 118                                MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
 119                                SectionKind::getDataRel());
 120
 121   StaticDtorSection =
 122     getContext().getELFSection(".dtors", MCSectionELF::SHT_PROGBITS,
 123                                MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
 124                                SectionKind::getDataRel());
 125
 126   // Exception Handling Sections.
 127
 128   // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
 129   // it contains relocatable pointers.  In PIC mode, this is probably a big
 130   // runtime hit for C++ apps.  Either the contents of the LSDA need to be
 131   // adjusted or this should be a data section.
 132   LSDASection =
 133     getContext().getELFSection(".gcc_except_table", MCSectionELF::SHT_PROGBITS,
 134                                MCSectionELF::SHF_ALLOC,
 135                                SectionKind::getReadOnly());
 136   EHFrameSection =
 137     getContext().getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS,
 138                                MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE,
 139                                SectionKind::getDataRel());
 140
 141   // Debug Info Sections.
 142   DwarfAbbrevSection =
 143     getContext().getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0,
 144                                SectionKind::getMetadata());
 145   DwarfInfoSection =
 146     getContext().getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0,
 147                                SectionKind::getMetadata());
 148   DwarfLineSection =
 149     getContext().getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0,
 150                                SectionKind::getMetadata());
 151   DwarfFrameSection =
 152     getContext().getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0,
 153                                SectionKind::getMetadata());
 154   DwarfPubNamesSection =
 155     getContext().getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0,
 156                                SectionKind::getMetadata());
 157   DwarfPubTypesSection =
 158     getContext().getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0,
 159                                SectionKind::getMetadata());
 160   DwarfStrSection =
 161     getContext().getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0,
 162                                SectionKind::getMetadata());
 163   DwarfLocSection =
 164     getContext().getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0,
 165                                SectionKind::getMetadata());
 166   DwarfARangesSection =
 167     getContext().getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0,
 168                                SectionKind::getMetadata());
 169   DwarfRangesSection =
 170     getContext().getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0,
 171                                SectionKind::getMetadata());
 172   DwarfMacroInfoSection =
 173     getContext().getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0,
 174                                SectionKind::getMetadata());
 175 }
 176
 177
 178 static SectionKind
 179 getELFKindForNamedSection(StringRef Name, SectionKind K) {
 180   if (Name.empty() || Name[0] != '.') return K;
 181
 182   // Some lame default implementation based on some magic section names.
 183   if (Name == ".bss" ||
 184       Name.startswith(".bss.") ||
 185       Name.startswith(".gnu.linkonce.b.") ||
 186       Name.startswith(".llvm.linkonce.b.") ||
 187       Name == ".sbss" ||
 188       Name.startswith(".sbss.") ||
 189       Name.startswith(".gnu.linkonce.sb.") ||
 190       Name.startswith(".llvm.linkonce.sb."))
 191     return SectionKind::getBSS();
 192
 193   if (Name == ".tdata" ||
 194       Name.startswith(".tdata.") ||
 195       Name.startswith(".gnu.linkonce.td.") ||
 196       Name.startswith(".llvm.linkonce.td."))
 197     return SectionKind::getThreadData();
 198
 199   if (Name == ".tbss" ||
 200       Name.startswith(".tbss.") ||
 201       Name.startswith(".gnu.linkonce.tb.") ||
 202       Name.startswith(".llvm.linkonce.tb."))
 203     return SectionKind::getThreadBSS();
 204
 205   return K;
 206 }
 207
 208
 209 static unsigned getELFSectionType(StringRef Name, SectionKind K) {
 210
 211   if (Name == ".init_array")
 212     return MCSectionELF::SHT_INIT_ARRAY;
 213
 214   if (Name == ".fini_array")
 215     return MCSectionELF::SHT_FINI_ARRAY;
 216
 217   if (Name == ".preinit_array")
 218     return MCSectionELF::SHT_PREINIT_ARRAY;
 219
 220   if (K.isBSS() || K.isThreadBSS())
 221     return MCSectionELF::SHT_NOBITS;
 222
 223   return MCSectionELF::SHT_PROGBITS;
 224 }
 225
 226
 227 static unsigned
 228 getELFSectionFlags(SectionKind K) {
 229   unsigned Flags = 0;
 230
 231   if (!K.isMetadata())
 232     Flags |= MCSectionELF::SHF_ALLOC;
 233
 234   if (K.isText())
 235     Flags |= MCSectionELF::SHF_EXECINSTR;
 236
 237   if (K.isWriteable())
 238     Flags |= MCSectionELF::SHF_WRITE;
 239
 240   if (K.isThreadLocal())
 241     Flags |= MCSectionELF::SHF_TLS;
 242
 243   // K.isMergeableConst() is left out to honour PR4650
 244   if (K.isMergeableCString() || K.isMergeableConst4() ||
 245       K.isMergeableConst8() || K.isMergeableConst16())
 246     Flags |= MCSectionELF::SHF_MERGE;
 247
 248   if (K.isMergeableCString())
 249     Flags |= MCSectionELF::SHF_STRINGS;
 250
 251   return Flags;
 252 }
 253
 254
 255 const MCSection *TargetLoweringObjectFileELF::
 256 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 257                          Mangler *Mang, const TargetMachine &TM) const {
 258   StringRef SectionName = GV->getSection();
 259
 260   // Infer section flags from the section name if we can.
 261   Kind = getELFKindForNamedSection(SectionName, Kind);
 262
 263   return getContext().getELFSection(SectionName,
 264                                     getELFSectionType(SectionName, Kind),
 265                                     getELFSectionFlags(Kind), Kind);
 266 }
 267
 268 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) {
 269   if (Kind.isText())                 return ".gnu.linkonce.t.";
 270   if (Kind.isReadOnly())             return ".gnu.linkonce.r.";
 271
 272   if (Kind.isThreadData())           return ".gnu.linkonce.td.";
 273   if (Kind.isThreadBSS())            return ".gnu.linkonce.tb.";
 274
 275   if (Kind.isDataNoRel())            return ".gnu.linkonce.d.";
 276   if (Kind.isDataRelLocal())         return ".gnu.linkonce.d.rel.local.";
 277   if (Kind.isDataRel())              return ".gnu.linkonce.d.rel.";
 278   if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local.";
 279
 280   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 281   return ".gnu.linkonce.d.rel.ro.";
 282 }
 283
 284 /// getSectionPrefixForGlobal - Return the section prefix name used by options
 285 /// FunctionsSections and DataSections.
 286 static const char *getSectionPrefixForGlobal(SectionKind Kind) {
 287   if (Kind.isText())                 return ".text.";
 288   if (Kind.isReadOnly())             return ".rodata.";
 289
 290   if (Kind.isThreadData())           return ".tdata.";
 291   if (Kind.isThreadBSS())            return ".tbss.";
 292
 293   if (Kind.isDataNoRel())            return ".data.";
 294   if (Kind.isDataRelLocal())         return ".data.rel.local.";
 295   if (Kind.isDataRel())              return ".data.rel.";
 296   if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local.";
 297
 298   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 299   return ".data.rel.ro.";
 300 }
 301
 302
 303 const MCSection *TargetLoweringObjectFileELF::
 304 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 305                        Mangler *Mang, const TargetMachine &TM) const {
 306   // If we have -ffunction-section or -fdata-section then we should emit the
 307   // global value to a uniqued section specifically for it.
 308   bool EmitUniquedSection;
 309   if (Kind.isText())
 310     EmitUniquedSection = TM.getFunctionSections();
 311   else
 312     EmitUniquedSection = TM.getDataSections();
 313
 314   // If this global is linkonce/weak and the target handles this by emitting it
 315   // into a 'uniqued' section name, create and return the section now.
 316   if ((GV->isWeakForLinker() || EmitUniquedSection) &&
 317       !Kind.isCommon() && !Kind.isBSS()) {
 318     const char *Prefix;
 319     if (GV->isWeakForLinker())
 320       Prefix = getSectionPrefixForUniqueGlobal(Kind);
 321     else {
 322       assert(EmitUniquedSection);
 323       Prefix = getSectionPrefixForGlobal(Kind);
 324     }
 325
 326     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
 327     MCSymbol *Sym = Mang->getSymbol(GV);
 328     Name.append(Sym->getName().begin(), Sym->getName().end());
 329     return getContext().getELFSection(Name.str(),
 330                                       getELFSectionType(Name.str(), Kind),
 331                                       getELFSectionFlags(Kind), Kind);
 332   }
 333
 334   if (Kind.isText()) return TextSection;
 335
 336   if (Kind.isMergeable1ByteCString() ||
 337       Kind.isMergeable2ByteCString() ||
 338       Kind.isMergeable4ByteCString()) {
 339
 340     // We also need alignment here.
 341     // FIXME: this is getting the alignment of the character, not the
 342     // alignment of the global!
 343     unsigned Align =
 344       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
 345
 346     const char *SizeSpec = ".rodata.str1.";
 347     if (Kind.isMergeable2ByteCString())
 348       SizeSpec = ".rodata.str2.";
 349     else if (Kind.isMergeable4ByteCString())
 350       SizeSpec = ".rodata.str4.";
 351     else
 352       assert(Kind.isMergeable1ByteCString() && "unknown string width");
 353
 354
 355     std::string Name = SizeSpec + utostr(Align);
 356     return getContext().getELFSection(Name, MCSectionELF::SHT_PROGBITS,
 357                                       MCSectionELF::SHF_ALLOC |
 358                                       MCSectionELF::SHF_MERGE |
 359                                       MCSectionELF::SHF_STRINGS,
 360                                       Kind);
 361   }
 362
 363   if (Kind.isMergeableConst()) {
 364     if (Kind.isMergeableConst4() && MergeableConst4Section)
 365       return MergeableConst4Section;
 366     if (Kind.isMergeableConst8() && MergeableConst8Section)
 367       return MergeableConst8Section;
 368     if (Kind.isMergeableConst16() && MergeableConst16Section)
 369       return MergeableConst16Section;
 370     return ReadOnlySection;  // .const
 371   }
 372
 373   if (Kind.isReadOnly())             return ReadOnlySection;
 374
 375   if (Kind.isThreadData())           return TLSDataSection;
 376   if (Kind.isThreadBSS())            return TLSBSSSection;
 377
 378   // Note: we claim that common symbols are put in BSSSection, but they are
 379   // really emitted with the magic .comm directive, which creates a symbol table
 380   // entry but not a section.
 381   if (Kind.isBSS() || Kind.isCommon()) return BSSSection;
 382
 383   if (Kind.isDataNoRel())            return DataSection;
 384   if (Kind.isDataRelLocal())         return DataRelLocalSection;
 385   if (Kind.isDataRel())              return DataRelSection;
 386   if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
 387
 388   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 389   return DataRelROSection;
 390 }
 391
 392 /// getSectionForConstant - Given a mergeable constant with the
 393 /// specified size and relocation information, return a section that it
 394 /// should be placed in.
 395 const MCSection *TargetLoweringObjectFileELF::
 396 getSectionForConstant(SectionKind Kind) const {
 397   if (Kind.isMergeableConst4() && MergeableConst4Section)
 398     return MergeableConst4Section;
 399   if (Kind.isMergeableConst8() && MergeableConst8Section)
 400     return MergeableConst8Section;
 401   if (Kind.isMergeableConst16() && MergeableConst16Section)
 402     return MergeableConst16Section;
 403   if (Kind.isReadOnly())
 404     return ReadOnlySection;
 405
 406   if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
 407   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 408   return DataRelROSection;
 409 }
 410
 411 const MCExpr *TargetLoweringObjectFileELF::
 412 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
 413                                MachineModuleInfo *MMI,
 414                                unsigned Encoding, MCStreamer &Streamer) const {
 415
 416   if (Encoding & dwarf::DW_EH_PE_indirect) {
 417     MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>();
 418
 419     SmallString<128> Name;
 420     Mang->getNameWithPrefix(Name, GV, true);
 421     Name += ".DW.stub";
 422
 423     // Add information about the stub reference to ELFMMI so that the stub
 424     // gets emitted by the asmprinter.
 425     MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
 426     MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym);
 427     if (StubSym.getPointer() == 0) {
 428       MCSymbol *Sym = Mang->getSymbol(GV);
 429       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
 430     }
 431
 432     return TargetLoweringObjectFile::
 433       getExprForDwarfReference(SSym, Mang, MMI,
 434                                Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
 435   }
 436
 437   return TargetLoweringObjectFile::
 438     getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
 439 }
 440
 441 //===----------------------------------------------------------------------===//
 442 //                                 MachO
 443 //===----------------------------------------------------------------------===//
 444
 445 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
 446                                                const TargetMachine &TM) {
 447   // _foo.eh symbols are currently always exported so that the linker knows
 448   // about them.  This is not necessary on 10.6 and later, but it
 449   // doesn't hurt anything.
 450   // FIXME: I need to get this from Triple.
 451   IsFunctionEHSymbolGlobal = true;
 452   IsFunctionEHFrameSymbolPrivate = false;
 453   SupportsWeakOmittedEHFrame = false;
 454
 455   Triple T(((LLVMTargetMachine&)TM).getTargetTriple());
 456   if (T.getOS() == Triple::Darwin) {
 457     switch (T.getDarwinMajorNumber()) {
 458     case 7:  // 10.3 Panther.
 459     case 8:  // 10.4 Tiger.
 460       CommDirectiveSupportsAlignment = false;
 461       break;
 462     case 9:   // 10.5 Leopard.
 463     case 10:  // 10.6 SnowLeopard.
 464       break;
 465     }
 466   }
 467
 468   TargetLoweringObjectFile::Initialize(Ctx, TM);
 469
 470   TextSection // .text
 471     = getContext().getMachOSection("__TEXT", "__text",
 472                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 473                                    SectionKind::getText());
 474   DataSection // .data
 475     = getContext().getMachOSection("__DATA", "__data", 0,
 476                                    SectionKind::getDataRel());
 477
 478   TLSDataSection // .tdata
 479     = getContext().getMachOSection("__DATA", "__thread_data",
 480                                    MCSectionMachO::S_THREAD_LOCAL_REGULAR,
 481                                    SectionKind::getDataRel());
 482   TLSBSSSection // .tbss
 483     = getContext().getMachOSection("__DATA", "__thread_bss",
 484                                    MCSectionMachO::S_THREAD_LOCAL_ZEROFILL,
 485                                    SectionKind::getThreadBSS());
 486
 487   // TODO: Verify datarel below.
 488   TLSTLVSection // .tlv
 489     = getContext().getMachOSection("__DATA", "__thread_vars",
 490                                    MCSectionMachO::S_THREAD_LOCAL_VARIABLES,
 491                                    SectionKind::getDataRel());
 492
 493   TLSThreadInitSection
 494     = getContext().getMachOSection("__DATA", "__thread_init",
 495                           MCSectionMachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS,
 496                           SectionKind::getDataRel());
 497
 498   CStringSection // .cstring
 499     = getContext().getMachOSection("__TEXT", "__cstring",
 500                                    MCSectionMachO::S_CSTRING_LITERALS,
 501                                    SectionKind::getMergeable1ByteCString());
 502   UStringSection
 503     = getContext().getMachOSection("__TEXT","__ustring", 0,
 504                                    SectionKind::getMergeable2ByteCString());
 505   FourByteConstantSection // .literal4
 506     = getContext().getMachOSection("__TEXT", "__literal4",
 507                                    MCSectionMachO::S_4BYTE_LITERALS,
 508                                    SectionKind::getMergeableConst4());
 509   EightByteConstantSection // .literal8
 510     = getContext().getMachOSection("__TEXT", "__literal8",
 511                                    MCSectionMachO::S_8BYTE_LITERALS,
 512                                    SectionKind::getMergeableConst8());
 513
 514   // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
 515   // to using it in -static mode.
 516   SixteenByteConstantSection = 0;
 517   if (TM.getRelocationModel() != Reloc::Static &&
 518       TM.getTargetData()->getPointerSize() == 32)
 519     SixteenByteConstantSection =   // .literal16
 520       getContext().getMachOSection("__TEXT", "__literal16",
 521                                    MCSectionMachO::S_16BYTE_LITERALS,
 522                                    SectionKind::getMergeableConst16());
 523
 524   ReadOnlySection  // .const
 525     = getContext().getMachOSection("__TEXT", "__const", 0,
 526                                    SectionKind::getReadOnly());
 527
 528   TextCoalSection
 529     = getContext().getMachOSection("__TEXT", "__textcoal_nt",
 530                                    MCSectionMachO::S_COALESCED |
 531                                    MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 532                                    SectionKind::getText());
 533   ConstTextCoalSection
 534     = getContext().getMachOSection("__TEXT", "__const_coal",
 535                                    MCSectionMachO::S_COALESCED,
 536                                    SectionKind::getReadOnly());
 537   ConstDataSection  // .const_data
 538     = getContext().getMachOSection("__DATA", "__const", 0,
 539                                    SectionKind::getReadOnlyWithRel());
 540   DataCoalSection
 541     = getContext().getMachOSection("__DATA","__datacoal_nt",
 542                                    MCSectionMachO::S_COALESCED,
 543                                    SectionKind::getDataRel());
 544   DataCommonSection
 545     = getContext().getMachOSection("__DATA","__common",
 546                                    MCSectionMachO::S_ZEROFILL,
 547                                    SectionKind::getBSS());
 548   DataBSSSection
 549     = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL,
 550                                    SectionKind::getBSS());
 551
 552
 553   LazySymbolPointerSection
 554     = getContext().getMachOSection("__DATA", "__la_symbol_ptr",
 555                                    MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
 556                                    SectionKind::getMetadata());
 557   NonLazySymbolPointerSection
 558     = getContext().getMachOSection("__DATA", "__nl_symbol_ptr",
 559                                    MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
 560                                    SectionKind::getMetadata());
 561
 562   if (TM.getRelocationModel() == Reloc::Static) {
 563     StaticCtorSection
 564       = getContext().getMachOSection("__TEXT", "__constructor", 0,
 565                                      SectionKind::getDataRel());
 566     StaticDtorSection
 567       = getContext().getMachOSection("__TEXT", "__destructor", 0,
 568                                      SectionKind::getDataRel());
 569   } else {
 570     StaticCtorSection
 571       = getContext().getMachOSection("__DATA", "__mod_init_func",
 572                                      MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
 573                                      SectionKind::getDataRel());
 574     StaticDtorSection
 575       = getContext().getMachOSection("__DATA", "__mod_term_func",
 576                                      MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
 577                                      SectionKind::getDataRel());
 578   }
 579
 580   // Exception Handling.
 581   LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0,
 582                                              SectionKind::getReadOnlyWithRel());
 583   EHFrameSection =
 584     getContext().getMachOSection("__TEXT", "__eh_frame",
 585                                  MCSectionMachO::S_COALESCED |
 586                                  MCSectionMachO::S_ATTR_NO_TOC |
 587                                  MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
 588                                  MCSectionMachO::S_ATTR_LIVE_SUPPORT,
 589                                  SectionKind::getReadOnly());
 590
 591   // Debug Information.
 592   DwarfAbbrevSection =
 593     getContext().getMachOSection("__DWARF", "__debug_abbrev",
 594                                  MCSectionMachO::S_ATTR_DEBUG,
 595                                  SectionKind::getMetadata());
 596   DwarfInfoSection =
 597     getContext().getMachOSection("__DWARF", "__debug_info",
 598                                  MCSectionMachO::S_ATTR_DEBUG,
 599                                  SectionKind::getMetadata());
 600   DwarfLineSection =
 601     getContext().getMachOSection("__DWARF", "__debug_line",
 602                                  MCSectionMachO::S_ATTR_DEBUG,
 603                                  SectionKind::getMetadata());
 604   DwarfFrameSection =
 605     getContext().getMachOSection("__DWARF", "__debug_frame",
 606                                  MCSectionMachO::S_ATTR_DEBUG,
 607                                  SectionKind::getMetadata());
 608   DwarfPubNamesSection =
 609     getContext().getMachOSection("__DWARF", "__debug_pubnames",
 610                                  MCSectionMachO::S_ATTR_DEBUG,
 611                                  SectionKind::getMetadata());
 612   DwarfPubTypesSection =
 613     getContext().getMachOSection("__DWARF", "__debug_pubtypes",
 614                                  MCSectionMachO::S_ATTR_DEBUG,
 615                                  SectionKind::getMetadata());
 616   DwarfStrSection =
 617     getContext().getMachOSection("__DWARF", "__debug_str",
 618                                  MCSectionMachO::S_ATTR_DEBUG,
 619                                  SectionKind::getMetadata());
 620   DwarfLocSection =
 621     getContext().getMachOSection("__DWARF", "__debug_loc",
 622                                  MCSectionMachO::S_ATTR_DEBUG,
 623                                  SectionKind::getMetadata());
 624   DwarfARangesSection =
 625     getContext().getMachOSection("__DWARF", "__debug_aranges",
 626                                  MCSectionMachO::S_ATTR_DEBUG,
 627                                  SectionKind::getMetadata());
 628   DwarfRangesSection =
 629     getContext().getMachOSection("__DWARF", "__debug_ranges",
 630                                  MCSectionMachO::S_ATTR_DEBUG,
 631                                  SectionKind::getMetadata());
 632   DwarfMacroInfoSection =
 633     getContext().getMachOSection("__DWARF", "__debug_macinfo",
 634                                  MCSectionMachO::S_ATTR_DEBUG,
 635                                  SectionKind::getMetadata());
 636   DwarfDebugInlineSection =
 637     getContext().getMachOSection("__DWARF", "__debug_inlined",
 638                                  MCSectionMachO::S_ATTR_DEBUG,
 639                                  SectionKind::getMetadata());
 640
 641   TLSExtraDataSection = TLSTLVSection;
 642 }
 643
 644 const MCSection *TargetLoweringObjectFileMachO::
 645 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 646                          Mangler *Mang, const TargetMachine &TM) const {
 647   // Parse the section specifier and create it if valid.
 648   StringRef Segment, Section;
 649   unsigned TAA, StubSize;
 650   std::string ErrorCode =
 651     MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
 652                                           TAA, StubSize);
 653   if (!ErrorCode.empty()) {
 654     // If invalid, report the error with report_fatal_error.
 655     report_fatal_error("Global variable '" + GV->getNameStr() +
 656                       "' has an invalid section specifier '" + GV->getSection()+
 657                       "': " + ErrorCode + ".");
 658     // Fall back to dropping it into the data section.
 659     return DataSection;
 660   }
 661
 662   // Get the section.
 663   const MCSectionMachO *S =
 664     getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind);
 665
 666   // Okay, now that we got the section, verify that the TAA & StubSize agree.
 667   // If the user declared multiple globals with different section flags, we need
 668   // to reject it here.
 669   if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
 670     // If invalid, report the error with report_fatal_error.
 671     report_fatal_error("Global variable '" + GV->getNameStr() +
 672                       "' section type or attributes does not match previous"
 673                       " section specifier");
 674   }
 675
 676   return S;
 677 }
 678
 679 const MCSection *TargetLoweringObjectFileMachO::
 680 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 681                        Mangler *Mang, const TargetMachine &TM) const {
 682
 683   // Handle thread local data.
 684   if (Kind.isThreadBSS()) return TLSBSSSection;
 685   if (Kind.isThreadData()) return TLSDataSection;
 686
 687   if (Kind.isText())
 688     return GV->isWeakForLinker() ? TextCoalSection : TextSection;
 689
 690   // If this is weak/linkonce, put this in a coalescable section, either in text
 691   // or data depending on if it is writable.
 692   if (GV->isWeakForLinker()) {
 693     if (Kind.isReadOnly())
 694       return ConstTextCoalSection;
 695     return DataCoalSection;
 696   }
 697
 698   // FIXME: Alignment check should be handled by section classifier.
 699   if (Kind.isMergeable1ByteCString() &&
 700       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
 701     return CStringSection;
 702
 703   // Do not put 16-bit arrays in the UString section if they have an
 704   // externally visible label, this runs into issues with certain linker
 705   // versions.
 706   if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() &&
 707       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32)
 708     return UStringSection;
 709
 710   if (Kind.isMergeableConst()) {
 711     if (Kind.isMergeableConst4())
 712       return FourByteConstantSection;
 713     if (Kind.isMergeableConst8())
 714       return EightByteConstantSection;
 715     if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 716       return SixteenByteConstantSection;
 717   }
 718
 719   // Otherwise, if it is readonly, but not something we can specially optimize,
 720   // just drop it in .const.
 721   if (Kind.isReadOnly())
 722     return ReadOnlySection;
 723
 724   // If this is marked const, put it into a const section.  But if the dynamic
 725   // linker needs to write to it, put it in the data segment.
 726   if (Kind.isReadOnlyWithRel())
 727     return ConstDataSection;
 728
 729   // Put zero initialized globals with strong external linkage in the
 730   // DATA, __common section with the .zerofill directive.
 731   if (Kind.isBSSExtern())
 732     return DataCommonSection;
 733
 734   // Put zero initialized globals with local linkage in __DATA,__bss directive
 735   // with the .zerofill directive (aka .lcomm).
 736   if (Kind.isBSSLocal())
 737     return DataBSSSection;
 738
 739   // Otherwise, just drop the variable in the normal data section.
 740   return DataSection;
 741 }
 742
 743 const MCSection *
 744 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
 745   // If this constant requires a relocation, we have to put it in the data
 746   // segment, not in the text segment.
 747   if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
 748     return ConstDataSection;
 749
 750   if (Kind.isMergeableConst4())
 751     return FourByteConstantSection;
 752   if (Kind.isMergeableConst8())
 753     return EightByteConstantSection;
 754   if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 755     return SixteenByteConstantSection;
 756   return ReadOnlySection;  // .const
 757 }
 758
 759 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
 760 /// not to emit the UsedDirective for some symbols in llvm.used.
 761 // FIXME: REMOVE this (rdar://7071300)
 762 bool TargetLoweringObjectFileMachO::
 763 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
 764   /// On Darwin, internally linked data beginning with "L" or "l" does not have
 765   /// the directive emitted (this occurs in ObjC metadata).
 766   if (!GV) return false;
 767
 768   // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
 769   if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
 770     // FIXME: ObjC metadata is currently emitted as internal symbols that have
 771     // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
 772     // this horrible hack can go away.
 773     MCSymbol *Sym = Mang->getSymbol(GV);
 774     if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l')
 775       return false;
 776   }
 777
 778   return true;
 779 }
 780
 781 const MCExpr *TargetLoweringObjectFileMachO::
 782 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
 783                                MachineModuleInfo *MMI, unsigned Encoding,
 784                                MCStreamer &Streamer) const {
 785   // The mach-o version of this method defaults to returning a stub reference.
 786
 787   if (Encoding & DW_EH_PE_indirect) {
 788     MachineModuleInfoMachO &MachOMMI =
 789       MMI->getObjFileInfo<MachineModuleInfoMachO>();
 790
 791     SmallString<128> Name;
 792     Mang->getNameWithPrefix(Name, GV, true);
 793     Name += "$non_lazy_ptr";
 794
 795     // Add information about the stub reference to MachOMMI so that the stub
 796     // gets emitted by the asmprinter.
 797     MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str());
 798     MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym);
 799     if (StubSym.getPointer() == 0) {
 800       MCSymbol *Sym = Mang->getSymbol(GV);
 801       StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage());
 802     }
 803
 804     return TargetLoweringObjectFile::
 805       getExprForDwarfReference(SSym, Mang, MMI,
 806                                Encoding & ~dwarf::DW_EH_PE_indirect, Streamer);
 807   }
 808
 809   return TargetLoweringObjectFile::
 810     getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer);
 811 }
 812
 813 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const {
 814   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
 815 }
 816
 817 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const {
 818   return DW_EH_PE_pcrel;
 819 }
 820
 821 unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const {
 822   return DW_EH_PE_pcrel;
 823 }
 824
 825 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const {
 826   return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4;
 827 }
 828
 829 //===----------------------------------------------------------------------===//
 830 //                                  COFF
 831 //===----------------------------------------------------------------------===//
 832
 833 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
 834                                               const TargetMachine &TM) {
 835   TargetLoweringObjectFile::Initialize(Ctx, TM);
 836   TextSection =
 837     getContext().getCOFFSection(".text",
 838                                 COFF::IMAGE_SCN_CNT_CODE |
 839                                 COFF::IMAGE_SCN_MEM_EXECUTE |
 840                                 COFF::IMAGE_SCN_MEM_READ,
 841                                 SectionKind::getText());
 842   DataSection =
 843     getContext().getCOFFSection(".data",
 844                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 845                                 COFF::IMAGE_SCN_MEM_READ |
 846                                 COFF::IMAGE_SCN_MEM_WRITE,
 847                                 SectionKind::getDataRel());
 848   ReadOnlySection =
 849     getContext().getCOFFSection(".rdata",
 850                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 851                                 COFF::IMAGE_SCN_MEM_READ,
 852                                 SectionKind::getReadOnly());
 853   StaticCtorSection =
 854     getContext().getCOFFSection(".ctors",
 855                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 856                                 COFF::IMAGE_SCN_MEM_READ |
 857                                 COFF::IMAGE_SCN_MEM_WRITE,
 858                                 SectionKind::getDataRel());
 859   StaticDtorSection =
 860     getContext().getCOFFSection(".dtors",
 861                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 862                                 COFF::IMAGE_SCN_MEM_READ |
 863                                 COFF::IMAGE_SCN_MEM_WRITE,
 864                                 SectionKind::getDataRel());
 865
 866   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
 867   // though it contains relocatable pointers.  In PIC mode, this is probably a
 868   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
 869   // adjusted or this should be a data section.
 870   LSDASection =
 871     getContext().getCOFFSection(".gcc_except_table",
 872                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 873                                 COFF::IMAGE_SCN_MEM_READ,
 874                                 SectionKind::getReadOnly());
 875   EHFrameSection =
 876     getContext().getCOFFSection(".eh_frame",
 877                                 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 878                                 COFF::IMAGE_SCN_MEM_READ |
 879                                 COFF::IMAGE_SCN_MEM_WRITE,
 880                                 SectionKind::getDataRel());
 881
 882   // Debug info.
 883   DwarfAbbrevSection =
 884     getContext().getCOFFSection(".debug_abbrev",
 885                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 886                                 COFF::IMAGE_SCN_MEM_READ,
 887                                 SectionKind::getMetadata());
 888   DwarfInfoSection =
 889     getContext().getCOFFSection(".debug_info",
 890                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 891                                 COFF::IMAGE_SCN_MEM_READ,
 892                                 SectionKind::getMetadata());
 893   DwarfLineSection =
 894     getContext().getCOFFSection(".debug_line",
 895                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 896                                 COFF::IMAGE_SCN_MEM_READ,
 897                                 SectionKind::getMetadata());
 898   DwarfFrameSection =
 899     getContext().getCOFFSection(".debug_frame",
 900                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 901                                 COFF::IMAGE_SCN_MEM_READ,
 902                                 SectionKind::getMetadata());
 903   DwarfPubNamesSection =
 904     getContext().getCOFFSection(".debug_pubnames",
 905                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 906                                 COFF::IMAGE_SCN_MEM_READ,
 907                                 SectionKind::getMetadata());
 908   DwarfPubTypesSection =
 909     getContext().getCOFFSection(".debug_pubtypes",
 910                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 911                                 COFF::IMAGE_SCN_MEM_READ,
 912                                 SectionKind::getMetadata());
 913   DwarfStrSection =
 914     getContext().getCOFFSection(".debug_str",
 915                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 916                                 COFF::IMAGE_SCN_MEM_READ,
 917                                 SectionKind::getMetadata());
 918   DwarfLocSection =
 919     getContext().getCOFFSection(".debug_loc",
 920                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 921                                 COFF::IMAGE_SCN_MEM_READ,
 922                                 SectionKind::getMetadata());
 923   DwarfARangesSection =
 924     getContext().getCOFFSection(".debug_aranges",
 925                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 926                                 COFF::IMAGE_SCN_MEM_READ,
 927                                 SectionKind::getMetadata());
 928   DwarfRangesSection =
 929     getContext().getCOFFSection(".debug_ranges",
 930                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 931                                 COFF::IMAGE_SCN_MEM_READ,
 932                                 SectionKind::getMetadata());
 933   DwarfMacroInfoSection =
 934     getContext().getCOFFSection(".debug_macinfo",
 935                                 COFF::IMAGE_SCN_MEM_DISCARDABLE |
 936                                 COFF::IMAGE_SCN_MEM_READ,
 937                                 SectionKind::getMetadata());
 938
 939   DrectveSection =
 940     getContext().getCOFFSection(".drectve",
 941                                 COFF::IMAGE_SCN_LNK_INFO,
 942                                 SectionKind::getMetadata());
 943 }
 944
 945 static unsigned
 946 getCOFFSectionFlags(SectionKind K) {
 947   unsigned Flags = 0;
 948
 949   if (K.isMetadata())
 950     Flags |=
 951       COFF::IMAGE_SCN_MEM_DISCARDABLE;
 952   else if (K.isText())
 953     Flags |=
 954       COFF::IMAGE_SCN_MEM_EXECUTE |
 955       COFF::IMAGE_SCN_MEM_READ |
 956       COFF::IMAGE_SCN_CNT_CODE;
 957   else if (K.isBSS ())
 958     Flags |=
 959       COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA |
 960       COFF::IMAGE_SCN_MEM_READ |
 961       COFF::IMAGE_SCN_MEM_WRITE;
 962   else if (K.isReadOnly())
 963     Flags |=
 964       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 965       COFF::IMAGE_SCN_MEM_READ;
 966   else if (K.isWriteable())
 967     Flags |=
 968       COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
 969       COFF::IMAGE_SCN_MEM_READ |
 970       COFF::IMAGE_SCN_MEM_WRITE;
 971
 972   return Flags;
 973 }
 974
 975 const MCSection *TargetLoweringObjectFileCOFF::
 976 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 977                          Mangler *Mang, const TargetMachine &TM) const {
 978   return getContext().getCOFFSection(GV->getSection(),
 979                                      getCOFFSectionFlags(Kind),
 980                                      Kind);
 981 }
 982
 983 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
 984   if (Kind.isText())
 985     return ".text$";
 986   if (Kind.isBSS ())
 987     return ".bss$";
 988   if (Kind.isWriteable())
 989     return ".data$";
 990   return ".rdata$";
 991 }
 992
 993
 994 const MCSection *TargetLoweringObjectFileCOFF::
 995 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 996                        Mangler *Mang, const TargetMachine &TM) const {
 997   assert(!Kind.isThreadLocal() && "Doesn't support TLS");
 998
 999   // If this global is linkonce/weak and the target handles this by emitting it
1000   // into a 'uniqued' section name, create and return the section now.
1001   if (GV->isWeakForLinker()) {
1002     const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
1003     SmallString<128> Name(Prefix, Prefix+strlen(Prefix));
1004     MCSymbol *Sym = Mang->getSymbol(GV);
1005     Name.append(Sym->getName().begin() + 1, Sym->getName().end());
1006
1007     unsigned Characteristics = getCOFFSectionFlags(Kind);
1008
1009     Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT;
1010
1011     return getContext().getCOFFSection(Name.str(), Characteristics,
1012                           COFF::IMAGE_COMDAT_SELECT_ANY, Kind);
1013   }
1014
1015   if (Kind.isText())
1016     return getTextSection();
1017
1018   return getDataSection();
1019 }
1020