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