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