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/MCStreamer.h" 27 #include "llvm/MC/MCSymbol.h" 28 #include "llvm/Target/Mangler.h" 29 #include "llvm/Target/TargetData.h" 30 #include "llvm/Target/TargetMachine.h" 31 #include "llvm/Target/TargetOptions.h" 32 #include "llvm/Support/Dwarf.h" 33 #include "llvm/Support/ELF.h" 34 #include "llvm/Support/ErrorHandling.h" 35 #include "llvm/Support/raw_ostream.h" 36 #include "llvm/ADT/SmallString.h" 37 #include "llvm/ADT/StringExtras.h" 38 #include "llvm/ADT/Triple.h" 39 using namespace llvm; 40 using namespace dwarf; 41 42 //===----------------------------------------------------------------------===// 43 // ELF 44 //===----------------------------------------------------------------------===// 45 46 MCSymbol * 47 TargetLoweringObjectFileELF::getCFIPersonalitySymbol(const GlobalValue *GV, 48 Mangler *Mang, 49 MachineModuleInfo *MMI) const { 50 unsigned Encoding = getPersonalityEncoding(); 51 switch (Encoding & 0x70) { 52 default: 53 report_fatal_error("We do not support this DWARF encoding yet!"); 54 case dwarf::DW_EH_PE_absptr: 55 return Mang->getSymbol(GV); 56 case dwarf::DW_EH_PE_pcrel: { 57 return getContext().GetOrCreateSymbol(StringRef("DW.ref.") + 58 Mang->getSymbol(GV)->getName()); 59 } 60 } 61 } 62 63 void TargetLoweringObjectFileELF::emitPersonalityValue(MCStreamer &Streamer, 64 const TargetMachine &TM, 65 const MCSymbol *Sym) const { 66 SmallString<64> NameData("DW.ref."); 67 NameData += Sym->getName(); 68 MCSymbol *Label = getContext().GetOrCreateSymbol(NameData); 69 Streamer.EmitSymbolAttribute(Label, MCSA_Hidden); 70 Streamer.EmitSymbolAttribute(Label, MCSA_Weak); 71 StringRef Prefix = ".data."; 72 NameData.insert(NameData.begin(), Prefix.begin(), Prefix.end()); 73 unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP; 74 const MCSection *Sec = getContext().getELFSection(NameData, 75 ELF::SHT_PROGBITS, 76 Flags, 77 SectionKind::getDataRel(), 78 0, Label->getName()); 79 Streamer.SwitchSection(Sec); 80 Streamer.EmitValueToAlignment(8); 81 Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject); 82 const MCExpr *E = MCConstantExpr::Create(8, getContext()); 83 Streamer.EmitELFSize(Label, E); 84 Streamer.EmitLabel(Label); 85 86 unsigned Size = TM.getTargetData()->getPointerSize(); 87 Streamer.EmitSymbolValue(Sym, Size); 88 } 89 90 static SectionKind 91 getELFKindForNamedSection(StringRef Name, SectionKind K) { 92 // N.B.: The defaults used in here are no the same ones used in MC. 93 // We follow gcc, MC follows gas. For example, given ".section .eh_frame", 94 // both gas and MC will produce a section with no flags. Given 95 // section(".eh_frame") gcc will produce 96 // .section .eh_frame,"a",@progbits 97 if (Name.empty() || Name[0] != '.') return K; 98 99 // Some lame default implementation based on some magic section names. 100 if (Name == ".bss" || 101 Name.startswith(".bss.") || 102 Name.startswith(".gnu.linkonce.b.") || 103 Name.startswith(".llvm.linkonce.b.") || 104 Name == ".sbss" || 105 Name.startswith(".sbss.") || 106 Name.startswith(".gnu.linkonce.sb.") || 107 Name.startswith(".llvm.linkonce.sb.")) 108 return SectionKind::getBSS(); 109 110 if (Name == ".tdata" || 111 Name.startswith(".tdata.") || 112 Name.startswith(".gnu.linkonce.td.") || 113 Name.startswith(".llvm.linkonce.td.")) 114 return SectionKind::getThreadData(); 115 116 if (Name == ".tbss" || 117 Name.startswith(".tbss.") || 118 Name.startswith(".gnu.linkonce.tb.") || 119 Name.startswith(".llvm.linkonce.tb.")) 120 return SectionKind::getThreadBSS(); 121 122 return K; 123 } 124 125 126 static unsigned getELFSectionType(StringRef Name, SectionKind K) { 127 128 if (Name == ".init_array") 129 return ELF::SHT_INIT_ARRAY; 130 131 if (Name == ".fini_array") 132 return ELF::SHT_FINI_ARRAY; 133 134 if (Name == ".preinit_array") 135 return ELF::SHT_PREINIT_ARRAY; 136 137 if (K.isBSS() || K.isThreadBSS()) 138 return ELF::SHT_NOBITS; 139 140 return ELF::SHT_PROGBITS; 141 } 142 143 144 static unsigned 145 getELFSectionFlags(SectionKind K) { 146 unsigned Flags = 0; 147 148 if (!K.isMetadata()) 149 Flags |= ELF::SHF_ALLOC; 150 151 if (K.isText()) 152 Flags |= ELF::SHF_EXECINSTR; 153 154 if (K.isWriteable()) 155 Flags |= ELF::SHF_WRITE; 156 157 if (K.isThreadLocal()) 158 Flags |= ELF::SHF_TLS; 159 160 // K.isMergeableConst() is left out to honour PR4650 161 if (K.isMergeableCString() || K.isMergeableConst4() || 162 K.isMergeableConst8() || K.isMergeableConst16()) 163 Flags |= ELF::SHF_MERGE; 164 165 if (K.isMergeableCString()) 166 Flags |= ELF::SHF_STRINGS; 167 168 return Flags; 169 } 170 171 172 const MCSection *TargetLoweringObjectFileELF:: 173 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 174 Mangler *Mang, const TargetMachine &TM) const { 175 StringRef SectionName = GV->getSection(); 176 177 // Infer section flags from the section name if we can. 178 Kind = getELFKindForNamedSection(SectionName, Kind); 179 180 return getContext().getELFSection(SectionName, 181 getELFSectionType(SectionName, Kind), 182 getELFSectionFlags(Kind), Kind); 183 } 184 185 /// getSectionPrefixForGlobal - Return the section prefix name used by options 186 /// FunctionsSections and DataSections. 187 static const char *getSectionPrefixForGlobal(SectionKind Kind) { 188 if (Kind.isText()) return ".text."; 189 if (Kind.isReadOnly()) return ".rodata."; 190 191 if (Kind.isThreadData()) return ".tdata."; 192 if (Kind.isThreadBSS()) return ".tbss."; 193 194 if (Kind.isDataNoRel()) return ".data."; 195 if (Kind.isDataRelLocal()) return ".data.rel.local."; 196 if (Kind.isDataRel()) return ".data.rel."; 197 if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local."; 198 199 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 200 return ".data.rel.ro."; 201 } 202 203 204 const MCSection *TargetLoweringObjectFileELF:: 205 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 206 Mangler *Mang, const TargetMachine &TM) const { 207 // If we have -ffunction-section or -fdata-section then we should emit the 208 // global value to a uniqued section specifically for it. 209 bool EmitUniquedSection; 210 if (Kind.isText()) 211 EmitUniquedSection = TM.getFunctionSections(); 212 else 213 EmitUniquedSection = TM.getDataSections(); 214 215 // If this global is linkonce/weak and the target handles this by emitting it 216 // into a 'uniqued' section name, create and return the section now. 217 if ((GV->isWeakForLinker() || EmitUniquedSection) && 218 !Kind.isCommon() && !Kind.isBSS()) { 219 const char *Prefix; 220 Prefix = getSectionPrefixForGlobal(Kind); 221 222 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 223 MCSymbol *Sym = Mang->getSymbol(GV); 224 Name.append(Sym->getName().begin(), Sym->getName().end()); 225 StringRef Group = ""; 226 unsigned Flags = getELFSectionFlags(Kind); 227 if (GV->isWeakForLinker()) { 228 Group = Sym->getName(); 229 Flags |= ELF::SHF_GROUP; 230 } 231 232 return getContext().getELFSection(Name.str(), 233 getELFSectionType(Name.str(), Kind), 234 Flags, Kind, 0, Group); 235 } 236 237 if (Kind.isText()) return TextSection; 238 239 if (Kind.isMergeable1ByteCString() || 240 Kind.isMergeable2ByteCString() || 241 Kind.isMergeable4ByteCString()) { 242 243 // We also need alignment here. 244 // FIXME: this is getting the alignment of the character, not the 245 // alignment of the global! 246 unsigned Align = 247 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)); 248 249 const char *SizeSpec = ".rodata.str1."; 250 if (Kind.isMergeable2ByteCString()) 251 SizeSpec = ".rodata.str2."; 252 else if (Kind.isMergeable4ByteCString()) 253 SizeSpec = ".rodata.str4."; 254 else 255 assert(Kind.isMergeable1ByteCString() && "unknown string width"); 256 257 258 std::string Name = SizeSpec + utostr(Align); 259 return getContext().getELFSection(Name, ELF::SHT_PROGBITS, 260 ELF::SHF_ALLOC | 261 ELF::SHF_MERGE | 262 ELF::SHF_STRINGS, 263 Kind); 264 } 265 266 if (Kind.isMergeableConst()) { 267 if (Kind.isMergeableConst4() && MergeableConst4Section) 268 return MergeableConst4Section; 269 if (Kind.isMergeableConst8() && MergeableConst8Section) 270 return MergeableConst8Section; 271 if (Kind.isMergeableConst16() && MergeableConst16Section) 272 return MergeableConst16Section; 273 return ReadOnlySection; // .const 274 } 275 276 if (Kind.isReadOnly()) return ReadOnlySection; 277 278 if (Kind.isThreadData()) return TLSDataSection; 279 if (Kind.isThreadBSS()) return TLSBSSSection; 280 281 // Note: we claim that common symbols are put in BSSSection, but they are 282 // really emitted with the magic .comm directive, which creates a symbol table 283 // entry but not a section. 284 if (Kind.isBSS() || Kind.isCommon()) return BSSSection; 285 286 if (Kind.isDataNoRel()) return DataSection; 287 if (Kind.isDataRelLocal()) return DataRelLocalSection; 288 if (Kind.isDataRel()) return DataRelSection; 289 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 290 291 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 292 return DataRelROSection; 293 } 294 295 /// getSectionForConstant - Given a mergeable constant with the 296 /// specified size and relocation information, return a section that it 297 /// should be placed in. 298 const MCSection *TargetLoweringObjectFileELF:: 299 getSectionForConstant(SectionKind Kind) const { 300 if (Kind.isMergeableConst4() && MergeableConst4Section) 301 return MergeableConst4Section; 302 if (Kind.isMergeableConst8() && MergeableConst8Section) 303 return MergeableConst8Section; 304 if (Kind.isMergeableConst16() && MergeableConst16Section) 305 return MergeableConst16Section; 306 if (Kind.isReadOnly()) 307 return ReadOnlySection; 308 309 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 310 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 311 return DataRelROSection; 312 } 313 314 const MCExpr *TargetLoweringObjectFileELF:: 315 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 316 MachineModuleInfo *MMI, 317 unsigned Encoding, MCStreamer &Streamer) const { 318 319 if (Encoding & dwarf::DW_EH_PE_indirect) { 320 MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>(); 321 322 SmallString<128> Name; 323 Mang->getNameWithPrefix(Name, GV, true); 324 Name += ".DW.stub"; 325 326 // Add information about the stub reference to ELFMMI so that the stub 327 // gets emitted by the asmprinter. 328 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); 329 MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym); 330 if (StubSym.getPointer() == 0) { 331 MCSymbol *Sym = Mang->getSymbol(GV); 332 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 333 } 334 335 return TargetLoweringObjectFile:: 336 getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 337 } 338 339 return TargetLoweringObjectFile:: 340 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); 341 } 342 343 //===----------------------------------------------------------------------===// 344 // MachO 345 //===----------------------------------------------------------------------===// 346 347 const MCSection *TargetLoweringObjectFileMachO:: 348 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 349 Mangler *Mang, const TargetMachine &TM) const { 350 // Parse the section specifier and create it if valid. 351 StringRef Segment, Section; 352 unsigned TAA = 0, StubSize = 0; 353 bool TAAParsed; 354 std::string ErrorCode = 355 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, 356 TAA, TAAParsed, StubSize); 357 if (!ErrorCode.empty()) { 358 // If invalid, report the error with report_fatal_error. 359 report_fatal_error("Global variable '" + GV->getName() + 360 "' has an invalid section specifier '" + 361 GV->getSection() + "': " + ErrorCode + "."); 362 } 363 364 // Get the section. 365 const MCSectionMachO *S = 366 getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind); 367 368 // If TAA wasn't set by ParseSectionSpecifier() above, 369 // use the value returned by getMachOSection() as a default. 370 if (!TAAParsed) 371 TAA = S->getTypeAndAttributes(); 372 373 // Okay, now that we got the section, verify that the TAA & StubSize agree. 374 // If the user declared multiple globals with different section flags, we need 375 // to reject it here. 376 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) { 377 // If invalid, report the error with report_fatal_error. 378 report_fatal_error("Global variable '" + GV->getName() + 379 "' section type or attributes does not match previous" 380 " section specifier"); 381 } 382 383 return S; 384 } 385 386 const MCSection *TargetLoweringObjectFileMachO:: 387 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 388 Mangler *Mang, const TargetMachine &TM) const { 389 390 // Handle thread local data. 391 if (Kind.isThreadBSS()) return TLSBSSSection; 392 if (Kind.isThreadData()) return TLSDataSection; 393 394 if (Kind.isText()) 395 return GV->isWeakForLinker() ? TextCoalSection : TextSection; 396 397 // If this is weak/linkonce, put this in a coalescable section, either in text 398 // or data depending on if it is writable. 399 if (GV->isWeakForLinker()) { 400 if (Kind.isReadOnly()) 401 return ConstTextCoalSection; 402 return DataCoalSection; 403 } 404 405 // FIXME: Alignment check should be handled by section classifier. 406 if (Kind.isMergeable1ByteCString() && 407 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 408 return CStringSection; 409 410 // Do not put 16-bit arrays in the UString section if they have an 411 // externally visible label, this runs into issues with certain linker 412 // versions. 413 if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() && 414 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 415 return UStringSection; 416 417 if (Kind.isMergeableConst()) { 418 if (Kind.isMergeableConst4()) 419 return FourByteConstantSection; 420 if (Kind.isMergeableConst8()) 421 return EightByteConstantSection; 422 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 423 return SixteenByteConstantSection; 424 } 425 426 // Otherwise, if it is readonly, but not something we can specially optimize, 427 // just drop it in .const. 428 if (Kind.isReadOnly()) 429 return ReadOnlySection; 430 431 // If this is marked const, put it into a const section. But if the dynamic 432 // linker needs to write to it, put it in the data segment. 433 if (Kind.isReadOnlyWithRel()) 434 return ConstDataSection; 435 436 // Put zero initialized globals with strong external linkage in the 437 // DATA, __common section with the .zerofill directive. 438 if (Kind.isBSSExtern()) 439 return DataCommonSection; 440 441 // Put zero initialized globals with local linkage in __DATA,__bss directive 442 // with the .zerofill directive (aka .lcomm). 443 if (Kind.isBSSLocal()) 444 return DataBSSSection; 445 446 // Otherwise, just drop the variable in the normal data section. 447 return DataSection; 448 } 449 450 const MCSection * 451 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { 452 // If this constant requires a relocation, we have to put it in the data 453 // segment, not in the text segment. 454 if (Kind.isDataRel() || Kind.isReadOnlyWithRel()) 455 return ConstDataSection; 456 457 if (Kind.isMergeableConst4()) 458 return FourByteConstantSection; 459 if (Kind.isMergeableConst8()) 460 return EightByteConstantSection; 461 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 462 return SixteenByteConstantSection; 463 return ReadOnlySection; // .const 464 } 465 466 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide 467 /// not to emit the UsedDirective for some symbols in llvm.used. 468 // FIXME: REMOVE this (rdar://7071300) 469 bool TargetLoweringObjectFileMachO:: 470 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { 471 /// On Darwin, internally linked data beginning with "L" or "l" does not have 472 /// the directive emitted (this occurs in ObjC metadata). 473 if (!GV) return false; 474 475 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. 476 if (GV->hasLocalLinkage() && !isa<Function>(GV)) { 477 // FIXME: ObjC metadata is currently emitted as internal symbols that have 478 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and 479 // this horrible hack can go away. 480 MCSymbol *Sym = Mang->getSymbol(GV); 481 if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l') 482 return false; 483 } 484 485 return true; 486 } 487 488 const MCExpr *TargetLoweringObjectFileMachO:: 489 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 490 MachineModuleInfo *MMI, unsigned Encoding, 491 MCStreamer &Streamer) const { 492 // The mach-o version of this method defaults to returning a stub reference. 493 494 if (Encoding & DW_EH_PE_indirect) { 495 MachineModuleInfoMachO &MachOMMI = 496 MMI->getObjFileInfo<MachineModuleInfoMachO>(); 497 498 SmallString<128> Name; 499 Mang->getNameWithPrefix(Name, GV, true); 500 Name += "$non_lazy_ptr"; 501 502 // Add information about the stub reference to MachOMMI so that the stub 503 // gets emitted by the asmprinter. 504 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); 505 MachineModuleInfoImpl::StubValueTy &StubSym = 506 GV->hasHiddenVisibility() ? MachOMMI.getHiddenGVStubEntry(SSym) : 507 MachOMMI.getGVStubEntry(SSym); 508 if (StubSym.getPointer() == 0) { 509 MCSymbol *Sym = Mang->getSymbol(GV); 510 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 511 } 512 513 return TargetLoweringObjectFile:: 514 getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 515 } 516 517 return TargetLoweringObjectFile:: 518 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); 519 } 520 521 MCSymbol *TargetLoweringObjectFileMachO:: 522 getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang, 523 MachineModuleInfo *MMI) const { 524 // The mach-o version of this method defaults to returning a stub reference. 525 MachineModuleInfoMachO &MachOMMI = 526 MMI->getObjFileInfo<MachineModuleInfoMachO>(); 527 528 SmallString<128> Name; 529 Mang->getNameWithPrefix(Name, GV, true); 530 Name += "$non_lazy_ptr"; 531 532 // Add information about the stub reference to MachOMMI so that the stub 533 // gets emitted by the asmprinter. 534 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); 535 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym); 536 if (StubSym.getPointer() == 0) { 537 MCSymbol *Sym = Mang->getSymbol(GV); 538 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 539 } 540 541 return SSym; 542 } 543 544 //===----------------------------------------------------------------------===// 545 // COFF 546 //===----------------------------------------------------------------------===// 547 548 static unsigned 549 getCOFFSectionFlags(SectionKind K) { 550 unsigned Flags = 0; 551 552 if (K.isMetadata()) 553 Flags |= 554 COFF::IMAGE_SCN_MEM_DISCARDABLE; 555 else if (K.isText()) 556 Flags |= 557 COFF::IMAGE_SCN_MEM_EXECUTE | 558 COFF::IMAGE_SCN_MEM_READ | 559 COFF::IMAGE_SCN_CNT_CODE; 560 else if (K.isBSS ()) 561 Flags |= 562 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA | 563 COFF::IMAGE_SCN_MEM_READ | 564 COFF::IMAGE_SCN_MEM_WRITE; 565 else if (K.isReadOnly()) 566 Flags |= 567 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 568 COFF::IMAGE_SCN_MEM_READ; 569 else if (K.isWriteable()) 570 Flags |= 571 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 572 COFF::IMAGE_SCN_MEM_READ | 573 COFF::IMAGE_SCN_MEM_WRITE; 574 575 return Flags; 576 } 577 578 const MCSection *TargetLoweringObjectFileCOFF:: 579 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 580 Mangler *Mang, const TargetMachine &TM) const { 581 return getContext().getCOFFSection(GV->getSection(), 582 getCOFFSectionFlags(Kind), 583 Kind); 584 } 585 586 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { 587 if (Kind.isText()) 588 return ".text$"; 589 if (Kind.isBSS ()) 590 return ".bss$"; 591 if (Kind.isWriteable()) 592 return ".data$"; 593 return ".rdata$"; 594 } 595 596 597 const MCSection *TargetLoweringObjectFileCOFF:: 598 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 599 Mangler *Mang, const TargetMachine &TM) const { 600 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 601 602 // If this global is linkonce/weak and the target handles this by emitting it 603 // into a 'uniqued' section name, create and return the section now. 604 if (GV->isWeakForLinker()) { 605 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); 606 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 607 MCSymbol *Sym = Mang->getSymbol(GV); 608 Name.append(Sym->getName().begin() + 1, Sym->getName().end()); 609 610 unsigned Characteristics = getCOFFSectionFlags(Kind); 611 612 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT; 613 614 return getContext().getCOFFSection(Name.str(), Characteristics, 615 COFF::IMAGE_COMDAT_SELECT_ANY, Kind); 616 } 617 618 if (Kind.isText()) 619 return getTextSection(); 620 621 return getDataSection(); 622 } 623 624