lib/Target/TargetLoweringObjectFile.cpp

   1 //===-- llvm/Target/TargetLoweringObjectFile.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/Target/TargetLoweringObjectFile.h"
  16 #include "llvm/Constants.h"
  17 #include "llvm/DerivedTypes.h"
  18 #include "llvm/Function.h"
  19 #include "llvm/GlobalVariable.h"
  20 #include "llvm/MC/MCContext.h"
  21 #include "llvm/MC/MCExpr.h"
  22 #include "llvm/MC/MCSectionMachO.h"
  23 #include "llvm/MC/MCSectionELF.h"
  24 #include "llvm/Target/TargetData.h"
  25 #include "llvm/Target/TargetMachine.h"
  26 #include "llvm/Target/TargetOptions.h"
  27 #include "llvm/Support/ErrorHandling.h"
  28 #include "llvm/Support/Mangler.h"
  29 #include "llvm/ADT/SmallString.h"
  30 #include "llvm/ADT/StringExtras.h"
  31 using namespace llvm;
  32
  33 //===----------------------------------------------------------------------===//
  34 //                              Generic Code
  35 //===----------------------------------------------------------------------===//
  36
  37 TargetLoweringObjectFile::TargetLoweringObjectFile() : Ctx(0) {
  38   TextSection = 0;
  39   DataSection = 0;
  40   BSSSection = 0;
  41   ReadOnlySection = 0;
  42   StaticCtorSection = 0;
  43   StaticDtorSection = 0;
  44   LSDASection = 0;
  45   EHFrameSection = 0;
  46
  47   DwarfAbbrevSection = 0;
  48   DwarfInfoSection = 0;
  49   DwarfLineSection = 0;
  50   DwarfFrameSection = 0;
  51   DwarfPubNamesSection = 0;
  52   DwarfPubTypesSection = 0;
  53   DwarfDebugInlineSection = 0;
  54   DwarfStrSection = 0;
  55   DwarfLocSection = 0;
  56   DwarfARangesSection = 0;
  57   DwarfRangesSection = 0;
  58   DwarfMacroInfoSection = 0;
  59 }
  60
  61 TargetLoweringObjectFile::~TargetLoweringObjectFile() {
  62 }
  63
  64 static bool isSuitableForBSS(const GlobalVariable *GV) {
  65   Constant *C = GV->getInitializer();
  66
  67   // Must have zero initializer.
  68   if (!C->isNullValue())
  69     return false;
  70
  71   // Leave constant zeros in readonly constant sections, so they can be shared.
  72   if (GV->isConstant())
  73     return false;
  74
  75   // If the global has an explicit section specified, don't put it in BSS.
  76   if (!GV->getSection().empty())
  77     return false;
  78
  79   // If -nozero-initialized-in-bss is specified, don't ever use BSS.
  80   if (NoZerosInBSS)
  81     return false;
  82
  83   // Otherwise, put it in BSS!
  84   return true;
  85 }
  86
  87 /// IsNullTerminatedString - Return true if the specified constant (which is
  88 /// known to have a type that is an array of 1/2/4 byte elements) ends with a
  89 /// nul value and contains no other nuls in it.
  90 static bool IsNullTerminatedString(const Constant *C) {
  91   const ArrayType *ATy = cast<ArrayType>(C->getType());
  92
  93   // First check: is we have constant array of i8 terminated with zero
  94   if (const ConstantArray *CVA = dyn_cast<ConstantArray>(C)) {
  95     if (ATy->getNumElements() == 0) return false;
  96
  97     ConstantInt *Null =
  98       dyn_cast<ConstantInt>(CVA->getOperand(ATy->getNumElements()-1));
  99     if (Null == 0 || Null->getZExtValue() != 0)
 100       return false; // Not null terminated.
 101
 102     // Verify that the null doesn't occur anywhere else in the string.
 103     for (unsigned i = 0, e = ATy->getNumElements()-1; i != e; ++i)
 104       // Reject constantexpr elements etc.
 105       if (!isa<ConstantInt>(CVA->getOperand(i)) ||
 106           CVA->getOperand(i) == Null)
 107         return false;
 108     return true;
 109   }
 110
 111   // Another possibility: [1 x i8] zeroinitializer
 112   if (isa<ConstantAggregateZero>(C))
 113     return ATy->getNumElements() == 1;
 114
 115   return false;
 116 }
 117
 118 /// getKindForGlobal - This is a top-level target-independent classifier for
 119 /// a global variable.  Given an global variable and information from TM, it
 120 /// classifies the global in a variety of ways that make various target
 121 /// implementations simpler.  The target implementation is free to ignore this
 122 /// extra info of course.
 123 SectionKind TargetLoweringObjectFile::getKindForGlobal(const GlobalValue *GV,
 124                                                        const TargetMachine &TM){
 125   assert(!GV->isDeclaration() && !GV->hasAvailableExternallyLinkage() &&
 126          "Can only be used for global definitions");
 127
 128   Reloc::Model ReloModel = TM.getRelocationModel();
 129
 130   // Early exit - functions should be always in text sections.
 131   const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV);
 132   if (GVar == 0)
 133     return SectionKind::getText();
 134
 135   // Handle thread-local data first.
 136   if (GVar->isThreadLocal()) {
 137     if (isSuitableForBSS(GVar))
 138       return SectionKind::getThreadBSS();
 139     return SectionKind::getThreadData();
 140   }
 141
 142   // Variable can be easily put to BSS section.
 143   if (isSuitableForBSS(GVar))
 144     return SectionKind::getBSS();
 145
 146   Constant *C = GVar->getInitializer();
 147
 148   // If the global is marked constant, we can put it into a mergable section,
 149   // a mergable string section, or general .data if it contains relocations.
 150   if (GVar->isConstant()) {
 151     // If the initializer for the global contains something that requires a
 152     // relocation, then we may have to drop this into a wriable data section
 153     // even though it is marked const.
 154     switch (C->getRelocationInfo()) {
 155     default: assert(0 && "unknown relocation info kind");
 156     case Constant::NoRelocation:
 157       // If initializer is a null-terminated string, put it in a "cstring"
 158       // section of the right width.
 159       if (const ArrayType *ATy = dyn_cast<ArrayType>(C->getType())) {
 160         if (const IntegerType *ITy =
 161               dyn_cast<IntegerType>(ATy->getElementType())) {
 162           if ((ITy->getBitWidth() == 8 || ITy->getBitWidth() == 16 ||
 163                ITy->getBitWidth() == 32) &&
 164               IsNullTerminatedString(C)) {
 165             if (ITy->getBitWidth() == 8)
 166               return SectionKind::getMergeable1ByteCString();
 167             if (ITy->getBitWidth() == 16)
 168               return SectionKind::getMergeable2ByteCString();
 169
 170             assert(ITy->getBitWidth() == 32 && "Unknown width");
 171             return SectionKind::getMergeable4ByteCString();
 172           }
 173         }
 174       }
 175
 176       // Otherwise, just drop it into a mergable constant section.  If we have
 177       // a section for this size, use it, otherwise use the arbitrary sized
 178       // mergable section.
 179       switch (TM.getTargetData()->getTypeAllocSize(C->getType())) {
 180       case 4:  return SectionKind::getMergeableConst4();
 181       case 8:  return SectionKind::getMergeableConst8();
 182       case 16: return SectionKind::getMergeableConst16();
 183       default: return SectionKind::getMergeableConst();
 184       }
 185
 186     case Constant::LocalRelocation:
 187       // In static relocation model, the linker will resolve all addresses, so
 188       // the relocation entries will actually be constants by the time the app
 189       // starts up.  However, we can't put this into a mergable section, because
 190       // the linker doesn't take relocations into consideration when it tries to
 191       // merge entries in the section.
 192       if (ReloModel == Reloc::Static)
 193         return SectionKind::getReadOnly();
 194
 195       // Otherwise, the dynamic linker needs to fix it up, put it in the
 196       // writable data.rel.local section.
 197       return SectionKind::getReadOnlyWithRelLocal();
 198
 199     case Constant::GlobalRelocations:
 200       // In static relocation model, the linker will resolve all addresses, so
 201       // the relocation entries will actually be constants by the time the app
 202       // starts up.  However, we can't put this into a mergable section, because
 203       // the linker doesn't take relocations into consideration when it tries to
 204       // merge entries in the section.
 205       if (ReloModel == Reloc::Static)
 206         return SectionKind::getReadOnly();
 207
 208       // Otherwise, the dynamic linker needs to fix it up, put it in the
 209       // writable data.rel section.
 210       return SectionKind::getReadOnlyWithRel();
 211     }
 212   }
 213
 214   // Okay, this isn't a constant.  If the initializer for the global is going
 215   // to require a runtime relocation by the dynamic linker, put it into a more
 216   // specific section to improve startup time of the app.  This coalesces these
 217   // globals together onto fewer pages, improving the locality of the dynamic
 218   // linker.
 219   if (ReloModel == Reloc::Static)
 220     return SectionKind::getDataNoRel();
 221
 222   switch (C->getRelocationInfo()) {
 223   default: assert(0 && "unknown relocation info kind");
 224   case Constant::NoRelocation:
 225     return SectionKind::getDataNoRel();
 226   case Constant::LocalRelocation:
 227     return SectionKind::getDataRelLocal();
 228   case Constant::GlobalRelocations:
 229     return SectionKind::getDataRel();
 230   }
 231 }
 232
 233 /// SectionForGlobal - This method computes the appropriate section to emit
 234 /// the specified global variable or function definition.  This should not
 235 /// be passed external (or available externally) globals.
 236 const MCSection *TargetLoweringObjectFile::
 237 SectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang,
 238                  const TargetMachine &TM) const {
 239   // Select section name.
 240   if (GV->hasSection())
 241     return getExplicitSectionGlobal(GV, Kind, Mang, TM);
 242
 243
 244   // Use default section depending on the 'type' of global
 245   return SelectSectionForGlobal(GV, Kind, Mang, TM);
 246 }
 247
 248
 249 // Lame default implementation. Calculate the section name for global.
 250 const MCSection *
 251 TargetLoweringObjectFile::SelectSectionForGlobal(const GlobalValue *GV,
 252                                                  SectionKind Kind,
 253                                                  Mangler *Mang,
 254                                                  const TargetMachine &TM) const{
 255   assert(!Kind.isThreadLocal() && "Doesn't support TLS");
 256
 257   if (Kind.isText())
 258     return getTextSection();
 259
 260   if (Kind.isBSS() && BSSSection != 0)
 261     return BSSSection;
 262
 263   if (Kind.isReadOnly() && ReadOnlySection != 0)
 264     return ReadOnlySection;
 265
 266   return getDataSection();
 267 }
 268
 269 /// getSectionForConstant - Given a mergable constant with the
 270 /// specified size and relocation information, return a section that it
 271 /// should be placed in.
 272 const MCSection *
 273 TargetLoweringObjectFile::getSectionForConstant(SectionKind Kind) const {
 274   if (Kind.isReadOnly() && ReadOnlySection != 0)
 275     return ReadOnlySection;
 276
 277   return DataSection;
 278 }
 279
 280 /// getSymbolForDwarfGlobalReference - Return an MCExpr to use for a
 281 /// pc-relative reference to the specified global variable from exception
 282 /// handling information.  In addition to the symbol, this returns
 283 /// by-reference:
 284 ///
 285 /// IsIndirect - True if the returned symbol is actually a stub that contains
 286 ///    the address of the symbol, false if the symbol is the global itself.
 287 ///
 288 /// IsPCRel - True if the symbol reference is already pc-relative, false if
 289 ///    the caller needs to subtract off the address of the reference from the
 290 ///    symbol.
 291 ///
 292 const MCExpr *TargetLoweringObjectFile::
 293 getSymbolForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
 294                                  MachineModuleInfo *MMI,
 295                                  bool &IsIndirect, bool &IsPCRel) const {
 296   // The generic implementation of this just returns a direct reference to the
 297   // symbol.
 298   IsIndirect = false;
 299   IsPCRel    = false;
 300
 301   SmallString<128> Name;
 302   Mang->getNameWithPrefix(Name, GV, false);
 303   return MCSymbolRefExpr::Create(Name.str(), getContext());
 304 }
 305
 306
 307 //===----------------------------------------------------------------------===//
 308 //                                  ELF
 309 //===----------------------------------------------------------------------===//
 310 typedef StringMap<const MCSectionELF*> ELFUniqueMapTy;
 311
 312 TargetLoweringObjectFileELF::~TargetLoweringObjectFileELF() {
 313   // If we have the section uniquing map, free it.
 314   delete (ELFUniqueMapTy*)UniquingMap;
 315 }
 316
 317 const MCSection *TargetLoweringObjectFileELF::
 318 getELFSection(StringRef Section, unsigned Type, unsigned Flags,
 319               SectionKind Kind, bool IsExplicit) const {
 320   if (UniquingMap == 0)
 321     UniquingMap = new ELFUniqueMapTy();
 322   ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)UniquingMap;
 323
 324   // Do the lookup, if we have a hit, return it.
 325   const MCSectionELF *&Entry = Map[Section];
 326   if (Entry) return Entry;
 327
 328   return Entry = MCSectionELF::Create(Section, Type, Flags, Kind, IsExplicit,
 329                                       getContext());
 330 }
 331
 332 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx,
 333                                              const TargetMachine &TM) {
 334   if (UniquingMap != 0)
 335     ((ELFUniqueMapTy*)UniquingMap)->clear();
 336   TargetLoweringObjectFile::Initialize(Ctx, TM);
 337
 338   BSSSection =
 339     getELFSection(".bss", MCSectionELF::SHT_NOBITS,
 340                   MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
 341                   SectionKind::getBSS());
 342
 343   TextSection =
 344     getELFSection(".text", MCSectionELF::SHT_PROGBITS,
 345                   MCSectionELF::SHF_EXECINSTR | MCSectionELF::SHF_ALLOC,
 346                   SectionKind::getText());
 347
 348   DataSection =
 349     getELFSection(".data", MCSectionELF::SHT_PROGBITS,
 350                   MCSectionELF::SHF_WRITE | MCSectionELF::SHF_ALLOC,
 351                   SectionKind::getDataRel());
 352
 353   ReadOnlySection =
 354     getELFSection(".rodata", MCSectionELF::SHT_PROGBITS,
 355                   MCSectionELF::SHF_ALLOC,
 356                   SectionKind::getReadOnly());
 357
 358   TLSDataSection =
 359     getELFSection(".tdata", MCSectionELF::SHT_PROGBITS,
 360                   MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
 361                   MCSectionELF::SHF_WRITE, SectionKind::getThreadData());
 362
 363   TLSBSSSection =
 364     getELFSection(".tbss", MCSectionELF::SHT_NOBITS,
 365                   MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS |
 366                   MCSectionELF::SHF_WRITE, SectionKind::getThreadBSS());
 367
 368   DataRelSection =
 369     getELFSection(".data.rel", MCSectionELF::SHT_PROGBITS,
 370                   MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
 371                   SectionKind::getDataRel());
 372
 373   DataRelLocalSection =
 374     getELFSection(".data.rel.local", MCSectionELF::SHT_PROGBITS,
 375                   MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
 376                   SectionKind::getDataRelLocal());
 377
 378   DataRelROSection =
 379     getELFSection(".data.rel.ro", MCSectionELF::SHT_PROGBITS,
 380                   MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
 381                   SectionKind::getReadOnlyWithRel());
 382
 383   DataRelROLocalSection =
 384     getELFSection(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS,
 385                   MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
 386                   SectionKind::getReadOnlyWithRelLocal());
 387
 388   MergeableConst4Section =
 389     getELFSection(".rodata.cst4", MCSectionELF::SHT_PROGBITS,
 390                   MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
 391                   SectionKind::getMergeableConst4());
 392
 393   MergeableConst8Section =
 394     getELFSection(".rodata.cst8", MCSectionELF::SHT_PROGBITS,
 395                   MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
 396                   SectionKind::getMergeableConst8());
 397
 398   MergeableConst16Section =
 399     getELFSection(".rodata.cst16", MCSectionELF::SHT_PROGBITS,
 400                   MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_MERGE,
 401                   SectionKind::getMergeableConst16());
 402
 403   StaticCtorSection =
 404     getELFSection(".ctors", MCSectionELF::SHT_PROGBITS,
 405                   MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
 406                   SectionKind::getDataRel());
 407
 408   StaticDtorSection =
 409     getELFSection(".dtors", MCSectionELF::SHT_PROGBITS,
 410                   MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
 411                   SectionKind::getDataRel());
 412
 413   // Exception Handling Sections.
 414
 415   // FIXME: We're emitting LSDA info into a readonly section on ELF, even though
 416   // it contains relocatable pointers.  In PIC mode, this is probably a big
 417   // runtime hit for C++ apps.  Either the contents of the LSDA need to be
 418   // adjusted or this should be a data section.
 419   LSDASection =
 420     getELFSection(".gcc_except_table", MCSectionELF::SHT_PROGBITS,
 421                   MCSectionELF::SHF_ALLOC, SectionKind::getReadOnly());
 422   EHFrameSection =
 423     getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS,
 424                   MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_WRITE,
 425                   SectionKind::getDataRel());
 426
 427   // Debug Info Sections.
 428   DwarfAbbrevSection =
 429     getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0,
 430                   SectionKind::getMetadata());
 431   DwarfInfoSection =
 432     getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0,
 433                   SectionKind::getMetadata());
 434   DwarfLineSection =
 435     getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0,
 436                   SectionKind::getMetadata());
 437   DwarfFrameSection =
 438     getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0,
 439                   SectionKind::getMetadata());
 440   DwarfPubNamesSection =
 441     getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0,
 442                   SectionKind::getMetadata());
 443   DwarfPubTypesSection =
 444     getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0,
 445                   SectionKind::getMetadata());
 446   DwarfStrSection =
 447     getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0,
 448                   SectionKind::getMetadata());
 449   DwarfLocSection =
 450     getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0,
 451                   SectionKind::getMetadata());
 452   DwarfARangesSection =
 453     getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0,
 454                   SectionKind::getMetadata());
 455   DwarfRangesSection =
 456     getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0,
 457                   SectionKind::getMetadata());
 458   DwarfMacroInfoSection =
 459     getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0,
 460                   SectionKind::getMetadata());
 461 }
 462
 463
 464 static SectionKind
 465 getELFKindForNamedSection(const char *Name, SectionKind K) {
 466   if (Name[0] != '.') return K;
 467
 468   // Some lame default implementation based on some magic section names.
 469   if (strcmp(Name, ".bss") == 0 ||
 470       strncmp(Name, ".bss.", 5) == 0 ||
 471       strncmp(Name, ".gnu.linkonce.b.", 16) == 0 ||
 472       strncmp(Name, ".llvm.linkonce.b.", 17) == 0 ||
 473       strcmp(Name, ".sbss") == 0 ||
 474       strncmp(Name, ".sbss.", 6) == 0 ||
 475       strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 ||
 476       strncmp(Name, ".llvm.linkonce.sb.", 18) == 0)
 477     return SectionKind::getBSS();
 478
 479   if (strcmp(Name, ".tdata") == 0 ||
 480       strncmp(Name, ".tdata.", 7) == 0 ||
 481       strncmp(Name, ".gnu.linkonce.td.", 17) == 0 ||
 482       strncmp(Name, ".llvm.linkonce.td.", 18) == 0)
 483     return SectionKind::getThreadData();
 484
 485   if (strcmp(Name, ".tbss") == 0 ||
 486       strncmp(Name, ".tbss.", 6) == 0 ||
 487       strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 ||
 488       strncmp(Name, ".llvm.linkonce.tb.", 18) == 0)
 489     return SectionKind::getThreadBSS();
 490
 491   return K;
 492 }
 493
 494
 495 static unsigned
 496 getELFSectionType(const char *Name, SectionKind K) {
 497
 498   if (strcmp(Name, ".init_array") == 0)
 499     return MCSectionELF::SHT_INIT_ARRAY;
 500
 501   if (strcmp(Name, ".fini_array") == 0)
 502     return MCSectionELF::SHT_FINI_ARRAY;
 503
 504   if (strcmp(Name, ".preinit_array") == 0)
 505     return MCSectionELF::SHT_PREINIT_ARRAY;
 506
 507   if (K.isBSS() || K.isThreadBSS())
 508     return MCSectionELF::SHT_NOBITS;
 509
 510   return MCSectionELF::SHT_PROGBITS;
 511 }
 512
 513
 514 static unsigned
 515 getELFSectionFlags(SectionKind K) {
 516   unsigned Flags = 0;
 517
 518   if (!K.isMetadata())
 519     Flags |= MCSectionELF::SHF_ALLOC;
 520
 521   if (K.isText())
 522     Flags |= MCSectionELF::SHF_EXECINSTR;
 523
 524   if (K.isWriteable())
 525     Flags |= MCSectionELF::SHF_WRITE;
 526
 527   if (K.isThreadLocal())
 528     Flags |= MCSectionELF::SHF_TLS;
 529
 530   // K.isMergeableConst() is left out to honour PR4650
 531   if (K.isMergeableCString() || K.isMergeableConst4() ||
 532       K.isMergeableConst8() || K.isMergeableConst16())
 533     Flags |= MCSectionELF::SHF_MERGE;
 534
 535   if (K.isMergeableCString())
 536     Flags |= MCSectionELF::SHF_STRINGS;
 537
 538   return Flags;
 539 }
 540
 541
 542 const MCSection *TargetLoweringObjectFileELF::
 543 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 544                          Mangler *Mang, const TargetMachine &TM) const {
 545   const char *SectionName = GV->getSection().c_str();
 546
 547   // Infer section flags from the section name if we can.
 548   Kind = getELFKindForNamedSection(SectionName, Kind);
 549
 550   return getELFSection(SectionName,
 551                        getELFSectionType(SectionName, Kind),
 552                        getELFSectionFlags(Kind), Kind, true);
 553 }
 554
 555 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) {
 556   if (Kind.isText())                 return ".gnu.linkonce.t.";
 557   if (Kind.isReadOnly())             return ".gnu.linkonce.r.";
 558
 559   if (Kind.isThreadData())           return ".gnu.linkonce.td.";
 560   if (Kind.isThreadBSS())            return ".gnu.linkonce.tb.";
 561
 562   if (Kind.isBSS())                  return ".gnu.linkonce.b.";
 563   if (Kind.isDataNoRel())            return ".gnu.linkonce.d.";
 564   if (Kind.isDataRelLocal())         return ".gnu.linkonce.d.rel.local.";
 565   if (Kind.isDataRel())              return ".gnu.linkonce.d.rel.";
 566   if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local.";
 567
 568   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 569   return ".gnu.linkonce.d.rel.ro.";
 570 }
 571
 572 const MCSection *TargetLoweringObjectFileELF::
 573 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 574                        Mangler *Mang, const TargetMachine &TM) const {
 575
 576   // If this global is linkonce/weak and the target handles this by emitting it
 577   // into a 'uniqued' section name, create and return the section now.
 578   if (GV->isWeakForLinker()) {
 579     const char *Prefix = getSectionPrefixForUniqueGlobal(Kind);
 580     std::string Name = Mang->makeNameProper(GV->getNameStr());
 581
 582     return getELFSection((Prefix+Name).c_str(),
 583                          getELFSectionType((Prefix+Name).c_str(), Kind),
 584                          getELFSectionFlags(Kind),
 585                          Kind);
 586   }
 587
 588   if (Kind.isText()) return TextSection;
 589
 590   if (Kind.isMergeable1ByteCString() ||
 591       Kind.isMergeable2ByteCString() ||
 592       Kind.isMergeable4ByteCString()) {
 593
 594     // We also need alignment here.
 595     // FIXME: this is getting the alignment of the character, not the
 596     // alignment of the global!
 597     unsigned Align =
 598       TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV));
 599
 600     const char *SizeSpec = ".rodata.str1.";
 601     if (Kind.isMergeable2ByteCString())
 602       SizeSpec = ".rodata.str2.";
 603     else if (Kind.isMergeable4ByteCString())
 604       SizeSpec = ".rodata.str4.";
 605     else
 606       assert(Kind.isMergeable1ByteCString() && "unknown string width");
 607
 608
 609     std::string Name = SizeSpec + utostr(Align);
 610     return getELFSection(Name.c_str(), MCSectionELF::SHT_PROGBITS,
 611                          MCSectionELF::SHF_ALLOC |
 612                          MCSectionELF::SHF_MERGE |
 613                          MCSectionELF::SHF_STRINGS,
 614                          Kind);
 615   }
 616
 617   if (Kind.isMergeableConst()) {
 618     if (Kind.isMergeableConst4() && MergeableConst4Section)
 619       return MergeableConst4Section;
 620     if (Kind.isMergeableConst8() && MergeableConst8Section)
 621       return MergeableConst8Section;
 622     if (Kind.isMergeableConst16() && MergeableConst16Section)
 623       return MergeableConst16Section;
 624     return ReadOnlySection;  // .const
 625   }
 626
 627   if (Kind.isReadOnly())             return ReadOnlySection;
 628
 629   if (Kind.isThreadData())           return TLSDataSection;
 630   if (Kind.isThreadBSS())            return TLSBSSSection;
 631
 632   if (Kind.isBSS())                  return BSSSection;
 633
 634   if (Kind.isDataNoRel())            return DataSection;
 635   if (Kind.isDataRelLocal())         return DataRelLocalSection;
 636   if (Kind.isDataRel())              return DataRelSection;
 637   if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
 638
 639   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 640   return DataRelROSection;
 641 }
 642
 643 /// getSectionForConstant - Given a mergeable constant with the
 644 /// specified size and relocation information, return a section that it
 645 /// should be placed in.
 646 const MCSection *TargetLoweringObjectFileELF::
 647 getSectionForConstant(SectionKind Kind) const {
 648   if (Kind.isMergeableConst4() && MergeableConst4Section)
 649     return MergeableConst4Section;
 650   if (Kind.isMergeableConst8() && MergeableConst8Section)
 651     return MergeableConst8Section;
 652   if (Kind.isMergeableConst16() && MergeableConst16Section)
 653     return MergeableConst16Section;
 654   if (Kind.isReadOnly())
 655     return ReadOnlySection;
 656
 657   if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection;
 658   assert(Kind.isReadOnlyWithRel() && "Unknown section kind");
 659   return DataRelROSection;
 660 }
 661
 662 //===----------------------------------------------------------------------===//
 663 //                                 MachO
 664 //===----------------------------------------------------------------------===//
 665
 666 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy;
 667
 668 TargetLoweringObjectFileMachO::~TargetLoweringObjectFileMachO() {
 669   // If we have the MachO uniquing map, free it.
 670   delete (MachOUniqueMapTy*)UniquingMap;
 671 }
 672
 673
 674 const MCSectionMachO *TargetLoweringObjectFileMachO::
 675 getMachOSection(StringRef Segment, StringRef Section,
 676                 unsigned TypeAndAttributes,
 677                 unsigned Reserved2, SectionKind Kind) const {
 678   // We unique sections by their segment/section pair.  The returned section
 679   // may not have the same flags as the requested section, if so this should be
 680   // diagnosed by the client as an error.
 681
 682   // Create the map if it doesn't already exist.
 683   if (UniquingMap == 0)
 684     UniquingMap = new MachOUniqueMapTy();
 685   MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)UniquingMap;
 686
 687   // Form the name to look up.
 688   SmallString<64> Name;
 689   Name += Segment;
 690   Name.push_back(',');
 691   Name += Section;
 692
 693   // Do the lookup, if we have a hit, return it.
 694   const MCSectionMachO *&Entry = Map[Name.str()];
 695   if (Entry) return Entry;
 696
 697   // Otherwise, return a new section.
 698   return Entry = MCSectionMachO::Create(Segment, Section, TypeAndAttributes,
 699                                         Reserved2, Kind, getContext());
 700 }
 701
 702
 703 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx,
 704                                                const TargetMachine &TM) {
 705   if (UniquingMap != 0)
 706     ((MachOUniqueMapTy*)UniquingMap)->clear();
 707   TargetLoweringObjectFile::Initialize(Ctx, TM);
 708
 709   TextSection // .text
 710     = getMachOSection("__TEXT", "__text",
 711                       MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 712                       SectionKind::getText());
 713   DataSection // .data
 714     = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel());
 715
 716   CStringSection // .cstring
 717     = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS,
 718                       SectionKind::getMergeable1ByteCString());
 719   UStringSection
 720     = getMachOSection("__TEXT","__ustring", 0,
 721                       SectionKind::getMergeable2ByteCString());
 722   FourByteConstantSection // .literal4
 723     = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS,
 724                       SectionKind::getMergeableConst4());
 725   EightByteConstantSection // .literal8
 726     = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS,
 727                       SectionKind::getMergeableConst8());
 728
 729   // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back
 730   // to using it in -static mode.
 731   SixteenByteConstantSection = 0;
 732   if (TM.getRelocationModel() != Reloc::Static &&
 733       TM.getTargetData()->getPointerSize() == 32)
 734     SixteenByteConstantSection =   // .literal16
 735       getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS,
 736                       SectionKind::getMergeableConst16());
 737
 738   ReadOnlySection  // .const
 739     = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly());
 740
 741   TextCoalSection
 742     = getMachOSection("__TEXT", "__textcoal_nt",
 743                       MCSectionMachO::S_COALESCED |
 744                       MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
 745                       SectionKind::getText());
 746   ConstTextCoalSection
 747     = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED,
 748                       SectionKind::getText());
 749   ConstDataCoalSection
 750     = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED,
 751                       SectionKind::getText());
 752   ConstDataSection  // .const_data
 753     = getMachOSection("__DATA", "__const", 0,
 754                       SectionKind::getReadOnlyWithRel());
 755   DataCoalSection
 756     = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED,
 757                       SectionKind::getDataRel());
 758
 759
 760   LazySymbolPointerSection
 761     = getMachOSection("__DATA", "__la_symbol_ptr",
 762                       MCSectionMachO::S_LAZY_SYMBOL_POINTERS,
 763                       SectionKind::getMetadata());
 764   NonLazySymbolPointerSection
 765     = getMachOSection("__DATA", "__nl_symbol_ptr",
 766                       MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS,
 767                       SectionKind::getMetadata());
 768
 769   if (TM.getRelocationModel() == Reloc::Static) {
 770     StaticCtorSection
 771       = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel());
 772     StaticDtorSection
 773       = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel());
 774   } else {
 775     StaticCtorSection
 776       = getMachOSection("__DATA", "__mod_init_func",
 777                         MCSectionMachO::S_MOD_INIT_FUNC_POINTERS,
 778                         SectionKind::getDataRel());
 779     StaticDtorSection
 780       = getMachOSection("__DATA", "__mod_term_func",
 781                         MCSectionMachO::S_MOD_TERM_FUNC_POINTERS,
 782                         SectionKind::getDataRel());
 783   }
 784
 785   // Exception Handling.
 786   LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0,
 787                                 SectionKind::getDataRel());
 788   EHFrameSection =
 789     getMachOSection("__TEXT", "__eh_frame",
 790                     MCSectionMachO::S_COALESCED |
 791                     MCSectionMachO::S_ATTR_NO_TOC |
 792                     MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS |
 793                     MCSectionMachO::S_ATTR_LIVE_SUPPORT,
 794                     SectionKind::getReadOnly());
 795
 796   // Debug Information.
 797   DwarfAbbrevSection =
 798     getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG,
 799                     SectionKind::getMetadata());
 800   DwarfInfoSection =
 801     getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG,
 802                     SectionKind::getMetadata());
 803   DwarfLineSection =
 804     getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG,
 805                     SectionKind::getMetadata());
 806   DwarfFrameSection =
 807     getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG,
 808                     SectionKind::getMetadata());
 809   DwarfPubNamesSection =
 810     getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG,
 811                     SectionKind::getMetadata());
 812   DwarfPubTypesSection =
 813     getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG,
 814                     SectionKind::getMetadata());
 815   DwarfStrSection =
 816     getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG,
 817                     SectionKind::getMetadata());
 818   DwarfLocSection =
 819     getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG,
 820                     SectionKind::getMetadata());
 821   DwarfARangesSection =
 822     getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG,
 823                     SectionKind::getMetadata());
 824   DwarfRangesSection =
 825     getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG,
 826                     SectionKind::getMetadata());
 827   DwarfMacroInfoSection =
 828     getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG,
 829                     SectionKind::getMetadata());
 830   DwarfDebugInlineSection =
 831     getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG,
 832                     SectionKind::getMetadata());
 833 }
 834
 835 const MCSection *TargetLoweringObjectFileMachO::
 836 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
 837                          Mangler *Mang, const TargetMachine &TM) const {
 838   // Parse the section specifier and create it if valid.
 839   StringRef Segment, Section;
 840   unsigned TAA, StubSize;
 841   std::string ErrorCode =
 842     MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section,
 843                                           TAA, StubSize);
 844   if (!ErrorCode.empty()) {
 845     // If invalid, report the error with llvm_report_error.
 846     llvm_report_error("Global variable '" + GV->getNameStr() +
 847                       "' has an invalid section specifier '" + GV->getSection()+
 848                       "': " + ErrorCode + ".");
 849     // Fall back to dropping it into the data section.
 850     return DataSection;
 851   }
 852
 853   // Get the section.
 854   const MCSectionMachO *S =
 855     getMachOSection(Segment, Section, TAA, StubSize, Kind);
 856
 857   // Okay, now that we got the section, verify that the TAA & StubSize agree.
 858   // If the user declared multiple globals with different section flags, we need
 859   // to reject it here.
 860   if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) {
 861     // If invalid, report the error with llvm_report_error.
 862     llvm_report_error("Global variable '" + GV->getNameStr() +
 863                       "' section type or attributes does not match previous"
 864                       " section specifier");
 865   }
 866
 867   return S;
 868 }
 869
 870 const MCSection *TargetLoweringObjectFileMachO::
 871 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
 872                        Mangler *Mang, const TargetMachine &TM) const {
 873   assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS");
 874
 875   if (Kind.isText())
 876     return GV->isWeakForLinker() ? TextCoalSection : TextSection;
 877
 878   // If this is weak/linkonce, put this in a coalescable section, either in text
 879   // or data depending on if it is writable.
 880   if (GV->isWeakForLinker()) {
 881     if (Kind.isReadOnly())
 882       return ConstTextCoalSection;
 883     return DataCoalSection;
 884   }
 885
 886   // FIXME: Alignment check should be handled by section classifier.
 887   if (Kind.isMergeable1ByteCString() ||
 888       Kind.isMergeable2ByteCString()) {
 889     if (TM.getTargetData()->getPreferredAlignment(
 890                                               cast<GlobalVariable>(GV)) < 32) {
 891       if (Kind.isMergeable1ByteCString())
 892         return CStringSection;
 893       assert(Kind.isMergeable2ByteCString());
 894       return UStringSection;
 895     }
 896   }
 897
 898   if (Kind.isMergeableConst()) {
 899     if (Kind.isMergeableConst4())
 900       return FourByteConstantSection;
 901     if (Kind.isMergeableConst8())
 902       return EightByteConstantSection;
 903     if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 904       return SixteenByteConstantSection;
 905   }
 906
 907   // Otherwise, if it is readonly, but not something we can specially optimize,
 908   // just drop it in .const.
 909   if (Kind.isReadOnly())
 910     return ReadOnlySection;
 911
 912   // If this is marked const, put it into a const section.  But if the dynamic
 913   // linker needs to write to it, put it in the data segment.
 914   if (Kind.isReadOnlyWithRel())
 915     return ConstDataSection;
 916
 917   // Otherwise, just drop the variable in the normal data section.
 918   return DataSection;
 919 }
 920
 921 const MCSection *
 922 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const {
 923   // If this constant requires a relocation, we have to put it in the data
 924   // segment, not in the text segment.
 925   if (Kind.isDataRel() || Kind.isReadOnlyWithRel())
 926     return ConstDataSection;
 927
 928   if (Kind.isMergeableConst4())
 929     return FourByteConstantSection;
 930   if (Kind.isMergeableConst8())
 931     return EightByteConstantSection;
 932   if (Kind.isMergeableConst16() && SixteenByteConstantSection)
 933     return SixteenByteConstantSection;
 934   return ReadOnlySection;  // .const
 935 }
 936
 937 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide
 938 /// not to emit the UsedDirective for some symbols in llvm.used.
 939 // FIXME: REMOVE this (rdar://7071300)
 940 bool TargetLoweringObjectFileMachO::
 941 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const {
 942   /// On Darwin, internally linked data beginning with "L" or "l" does not have
 943   /// the directive emitted (this occurs in ObjC metadata).
 944   if (!GV) return false;
 945
 946   // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix.
 947   if (GV->hasLocalLinkage() && !isa<Function>(GV)) {
 948     // FIXME: ObjC metadata is currently emitted as internal symbols that have
 949     // \1L and \0l prefixes on them.  Fix them to be Private/LinkerPrivate and
 950     // this horrible hack can go away.
 951     const std::string &Name = Mang->getMangledName(GV);
 952     if (Name[0] == 'L' || Name[0] == 'l')
 953       return false;
 954   }
 955
 956   return true;
 957 }
 958
 959 const MCExpr *TargetLoweringObjectFileMachO::
 960 getSymbolForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang,
 961                                  MachineModuleInfo *MMI,
 962                                  bool &IsIndirect, bool &IsPCRel) const {
 963   // The mach-o version of this method defaults to returning a stub reference.
 964   IsIndirect = true;
 965   IsPCRel    = false;
 966
 967   SmallString<128> Name;
 968   Mang->getNameWithPrefix(Name, GV, true);
 969   Name += "$non_lazy_ptr";
 970   return MCSymbolRefExpr::Create(Name.str(), getContext());
 971 }
 972
 973
 974 //===----------------------------------------------------------------------===//
 975 //                                  COFF
 976 //===----------------------------------------------------------------------===//
 977
 978 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy;
 979
 980 TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() {
 981   delete (COFFUniqueMapTy*)UniquingMap;
 982 }
 983
 984
 985 const MCSection *TargetLoweringObjectFileCOFF::
 986 getCOFFSection(const char *Name, bool isDirective, SectionKind Kind) const {
 987   // Create the map if it doesn't already exist.
 988   if (UniquingMap == 0)
 989     UniquingMap = new MachOUniqueMapTy();
 990   COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap;
 991
 992   // Do the lookup, if we have a hit, return it.
 993   const MCSectionCOFF *&Entry = Map[Name];
 994   if (Entry) return Entry;
 995
 996   return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext());
 997 }
 998
 999 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx,
1000                                               const TargetMachine &TM) {
1001   if (UniquingMap != 0)
1002     ((COFFUniqueMapTy*)UniquingMap)->clear();
1003   TargetLoweringObjectFile::Initialize(Ctx, TM);
1004   TextSection = getCOFFSection("\t.text", true, SectionKind::getText());
1005   DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel());
1006   StaticCtorSection =
1007     getCOFFSection(".ctors", false, SectionKind::getDataRel());
1008   StaticDtorSection =
1009     getCOFFSection(".dtors", false, SectionKind::getDataRel());
1010
1011   // FIXME: We're emitting LSDA info into a readonly section on COFF, even
1012   // though it contains relocatable pointers.  In PIC mode, this is probably a
1013   // big runtime hit for C++ apps.  Either the contents of the LSDA need to be
1014   // adjusted or this should be a data section.
1015   LSDASection =
1016     getCOFFSection(".gcc_except_table", false, SectionKind::getReadOnly());
1017   EHFrameSection =
1018     getCOFFSection(".eh_frame", false, SectionKind::getDataRel());
1019
1020   // Debug info.
1021   // FIXME: Don't use 'directive' mode here.
1022   DwarfAbbrevSection =
1023     getCOFFSection("\t.section\t.debug_abbrev,\"dr\"",
1024                    true, SectionKind::getMetadata());
1025   DwarfInfoSection =
1026     getCOFFSection("\t.section\t.debug_info,\"dr\"",
1027                    true, SectionKind::getMetadata());
1028   DwarfLineSection =
1029     getCOFFSection("\t.section\t.debug_line,\"dr\"",
1030                    true, SectionKind::getMetadata());
1031   DwarfFrameSection =
1032     getCOFFSection("\t.section\t.debug_frame,\"dr\"",
1033                    true, SectionKind::getMetadata());
1034   DwarfPubNamesSection =
1035     getCOFFSection("\t.section\t.debug_pubnames,\"dr\"",
1036                    true, SectionKind::getMetadata());
1037   DwarfPubTypesSection =
1038     getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"",
1039                    true, SectionKind::getMetadata());
1040   DwarfStrSection =
1041     getCOFFSection("\t.section\t.debug_str,\"dr\"",
1042                    true, SectionKind::getMetadata());
1043   DwarfLocSection =
1044     getCOFFSection("\t.section\t.debug_loc,\"dr\"",
1045                    true, SectionKind::getMetadata());
1046   DwarfARangesSection =
1047     getCOFFSection("\t.section\t.debug_aranges,\"dr\"",
1048                    true, SectionKind::getMetadata());
1049   DwarfRangesSection =
1050     getCOFFSection("\t.section\t.debug_ranges,\"dr\"",
1051                    true, SectionKind::getMetadata());
1052   DwarfMacroInfoSection =
1053     getCOFFSection("\t.section\t.debug_macinfo,\"dr\"",
1054                    true, SectionKind::getMetadata());
1055 }
1056
1057 const MCSection *TargetLoweringObjectFileCOFF::
1058 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind,
1059                          Mangler *Mang, const TargetMachine &TM) const {
1060   return getCOFFSection(GV->getSection().c_str(), false, Kind);
1061 }
1062
1063 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) {
1064   if (Kind.isText())
1065     return ".text$linkonce";
1066   if (Kind.isWriteable())
1067     return ".data$linkonce";
1068   return ".rdata$linkonce";
1069 }
1070
1071
1072 const MCSection *TargetLoweringObjectFileCOFF::
1073 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind,
1074                        Mangler *Mang, const TargetMachine &TM) const {
1075   assert(!Kind.isThreadLocal() && "Doesn't support TLS");
1076
1077   // If this global is linkonce/weak and the target handles this by emitting it
1078   // into a 'uniqued' section name, create and return the section now.
1079   if (GV->isWeakForLinker()) {
1080     const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind);
1081     std::string Name = Mang->makeNameProper(GV->getNameStr());
1082     return getCOFFSection((Prefix+Name).c_str(), false, Kind);
1083   }
1084
1085   if (Kind.isText())
1086     return getTextSection();
1087
1088   return getDataSection();
1089 }
1090