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 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx, 47 const TargetMachine &TM) { 48 TargetLoweringObjectFile::Initialize(Ctx, TM); 49 50 BSSSection = 51 getContext().getELFSection(".bss", ELF::SHT_NOBITS, 52 ELF::SHF_WRITE |ELF::SHF_ALLOC, 53 SectionKind::getBSS()); 54 55 TextSection = 56 getContext().getELFSection(".text", ELF::SHT_PROGBITS, 57 ELF::SHF_EXECINSTR | 58 ELF::SHF_ALLOC, 59 SectionKind::getText()); 60 61 DataSection = 62 getContext().getELFSection(".data", ELF::SHT_PROGBITS, 63 ELF::SHF_WRITE |ELF::SHF_ALLOC, 64 SectionKind::getDataRel()); 65 66 ReadOnlySection = 67 getContext().getELFSection(".rodata", ELF::SHT_PROGBITS, 68 ELF::SHF_ALLOC, 69 SectionKind::getReadOnly()); 70 71 TLSDataSection = 72 getContext().getELFSection(".tdata", ELF::SHT_PROGBITS, 73 ELF::SHF_ALLOC | ELF::SHF_TLS | 74 ELF::SHF_WRITE, 75 SectionKind::getThreadData()); 76 77 TLSBSSSection = 78 getContext().getELFSection(".tbss", ELF::SHT_NOBITS, 79 ELF::SHF_ALLOC | ELF::SHF_TLS | 80 ELF::SHF_WRITE, 81 SectionKind::getThreadBSS()); 82 83 DataRelSection = 84 getContext().getELFSection(".data.rel", ELF::SHT_PROGBITS, 85 ELF::SHF_ALLOC |ELF::SHF_WRITE, 86 SectionKind::getDataRel()); 87 88 DataRelLocalSection = 89 getContext().getELFSection(".data.rel.local", ELF::SHT_PROGBITS, 90 ELF::SHF_ALLOC |ELF::SHF_WRITE, 91 SectionKind::getDataRelLocal()); 92 93 DataRelROSection = 94 getContext().getELFSection(".data.rel.ro", ELF::SHT_PROGBITS, 95 ELF::SHF_ALLOC |ELF::SHF_WRITE, 96 SectionKind::getReadOnlyWithRel()); 97 98 DataRelROLocalSection = 99 getContext().getELFSection(".data.rel.ro.local", ELF::SHT_PROGBITS, 100 ELF::SHF_ALLOC |ELF::SHF_WRITE, 101 SectionKind::getReadOnlyWithRelLocal()); 102 103 MergeableConst4Section = 104 getContext().getELFSection(".rodata.cst4", ELF::SHT_PROGBITS, 105 ELF::SHF_ALLOC |ELF::SHF_MERGE, 106 SectionKind::getMergeableConst4()); 107 108 MergeableConst8Section = 109 getContext().getELFSection(".rodata.cst8", ELF::SHT_PROGBITS, 110 ELF::SHF_ALLOC |ELF::SHF_MERGE, 111 SectionKind::getMergeableConst8()); 112 113 MergeableConst16Section = 114 getContext().getELFSection(".rodata.cst16", ELF::SHT_PROGBITS, 115 ELF::SHF_ALLOC |ELF::SHF_MERGE, 116 SectionKind::getMergeableConst16()); 117 118 StaticCtorSection = 119 getContext().getELFSection(".ctors", ELF::SHT_PROGBITS, 120 ELF::SHF_ALLOC |ELF::SHF_WRITE, 121 SectionKind::getDataRel()); 122 123 StaticDtorSection = 124 getContext().getELFSection(".dtors", ELF::SHT_PROGBITS, 125 ELF::SHF_ALLOC |ELF::SHF_WRITE, 126 SectionKind::getDataRel()); 127 128 // Exception Handling Sections. 129 130 // FIXME: We're emitting LSDA info into a readonly section on ELF, even though 131 // it contains relocatable pointers. In PIC mode, this is probably a big 132 // runtime hit for C++ apps. Either the contents of the LSDA need to be 133 // adjusted or this should be a data section. 134 LSDASection = 135 getContext().getELFSection(".gcc_except_table", ELF::SHT_PROGBITS, 136 ELF::SHF_ALLOC, 137 SectionKind::getReadOnly()); 138 // Debug Info Sections. 139 DwarfAbbrevSection = 140 getContext().getELFSection(".debug_abbrev", ELF::SHT_PROGBITS, 0, 141 SectionKind::getMetadata()); 142 DwarfInfoSection = 143 getContext().getELFSection(".debug_info", ELF::SHT_PROGBITS, 0, 144 SectionKind::getMetadata()); 145 DwarfLineSection = 146 getContext().getELFSection(".debug_line", ELF::SHT_PROGBITS, 0, 147 SectionKind::getMetadata()); 148 DwarfFrameSection = 149 getContext().getELFSection(".debug_frame", ELF::SHT_PROGBITS, 0, 150 SectionKind::getMetadata()); 151 DwarfPubNamesSection = 152 getContext().getELFSection(".debug_pubnames", ELF::SHT_PROGBITS, 0, 153 SectionKind::getMetadata()); 154 DwarfPubTypesSection = 155 getContext().getELFSection(".debug_pubtypes", ELF::SHT_PROGBITS, 0, 156 SectionKind::getMetadata()); 157 DwarfStrSection = 158 getContext().getELFSection(".debug_str", ELF::SHT_PROGBITS, 0, 159 SectionKind::getMetadata()); 160 DwarfLocSection = 161 getContext().getELFSection(".debug_loc", ELF::SHT_PROGBITS, 0, 162 SectionKind::getMetadata()); 163 DwarfARangesSection = 164 getContext().getELFSection(".debug_aranges", ELF::SHT_PROGBITS, 0, 165 SectionKind::getMetadata()); 166 DwarfRangesSection = 167 getContext().getELFSection(".debug_ranges", ELF::SHT_PROGBITS, 0, 168 SectionKind::getMetadata()); 169 DwarfMacroInfoSection = 170 getContext().getELFSection(".debug_macinfo", ELF::SHT_PROGBITS, 0, 171 SectionKind::getMetadata()); 172 } 173 174 const MCSection *TargetLoweringObjectFileELF::getEHFrameSection() const { 175 return getContext().getELFSection(".eh_frame", ELF::SHT_PROGBITS, 176 ELF::SHF_ALLOC, 177 SectionKind::getDataRel()); 178 } 179 180 MCSymbol * 181 TargetLoweringObjectFileELF::getCFIPersonalitySymbol(const GlobalValue *GV, 182 Mangler *Mang, 183 MachineModuleInfo *MMI) const { 184 unsigned Encoding = getPersonalityEncoding(); 185 switch (Encoding & 0x70) { 186 default: 187 report_fatal_error("We do not support this DWARF encoding yet!"); 188 case dwarf::DW_EH_PE_absptr: 189 return Mang->getSymbol(GV); 190 break; 191 case dwarf::DW_EH_PE_pcrel: { 192 Twine FullName = StringRef("DW.ref.") + Mang->getSymbol(GV)->getName(); 193 return getContext().GetOrCreateSymbol(FullName); 194 break; 195 } 196 } 197 } 198 199 void TargetLoweringObjectFileELF::emitPersonalityValue(MCStreamer &Streamer, 200 const TargetMachine &TM, 201 const MCSymbol *Sym) const { 202 Twine FullName = StringRef("DW.ref.") + Sym->getName(); 203 MCSymbol *Label = getContext().GetOrCreateSymbol(FullName); 204 Streamer.EmitSymbolAttribute(Label, MCSA_Hidden); 205 Streamer.EmitSymbolAttribute(Label, MCSA_Weak); 206 Twine SectionName = StringRef(".data.") + Label->getName(); 207 SmallString<64> NameData; 208 SectionName.toVector(NameData); 209 unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP; 210 const MCSection *Sec = getContext().getELFSection(NameData, 211 ELF::SHT_PROGBITS, 212 Flags, 213 SectionKind::getDataRel(), 214 0, Label->getName()); 215 Streamer.SwitchSection(Sec); 216 Streamer.EmitValueToAlignment(8); 217 Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject); 218 const MCExpr *E = MCConstantExpr::Create(8, getContext()); 219 Streamer.EmitELFSize(Label, E); 220 Streamer.EmitLabel(Label); 221 222 unsigned Size = TM.getTargetData()->getPointerSize(); 223 Streamer.EmitSymbolValue(Sym, Size); 224 } 225 226 static SectionKind 227 getELFKindForNamedSection(StringRef Name, SectionKind K) { 228 // FIXME: Why is this here? Codegen is should not be in the business 229 // of figuring section flags. If the user wrote section(".eh_frame"), 230 // we should just pass that to MC which will defer to the assembly 231 // or use its default if producing an object file. 232 if (Name.empty() || Name[0] != '.') return K; 233 234 // Some lame default implementation based on some magic section names. 235 if (Name == ".bss" || 236 Name.startswith(".bss.") || 237 Name.startswith(".gnu.linkonce.b.") || 238 Name.startswith(".llvm.linkonce.b.") || 239 Name == ".sbss" || 240 Name.startswith(".sbss.") || 241 Name.startswith(".gnu.linkonce.sb.") || 242 Name.startswith(".llvm.linkonce.sb.")) 243 return SectionKind::getBSS(); 244 245 if (Name == ".tdata" || 246 Name.startswith(".tdata.") || 247 Name.startswith(".gnu.linkonce.td.") || 248 Name.startswith(".llvm.linkonce.td.")) 249 return SectionKind::getThreadData(); 250 251 if (Name == ".tbss" || 252 Name.startswith(".tbss.") || 253 Name.startswith(".gnu.linkonce.tb.") || 254 Name.startswith(".llvm.linkonce.tb.")) 255 return SectionKind::getThreadBSS(); 256 257 if (Name == ".eh_frame") 258 return SectionKind::getReadOnlyWithRel(); 259 260 return K; 261 } 262 263 264 static unsigned getELFSectionType(StringRef Name, SectionKind K) { 265 266 if (Name == ".init_array") 267 return ELF::SHT_INIT_ARRAY; 268 269 if (Name == ".fini_array") 270 return ELF::SHT_FINI_ARRAY; 271 272 if (Name == ".preinit_array") 273 return ELF::SHT_PREINIT_ARRAY; 274 275 if (K.isBSS() || K.isThreadBSS()) 276 return ELF::SHT_NOBITS; 277 278 return ELF::SHT_PROGBITS; 279 } 280 281 282 static unsigned 283 getELFSectionFlags(SectionKind K) { 284 unsigned Flags = 0; 285 286 if (!K.isMetadata()) 287 Flags |= ELF::SHF_ALLOC; 288 289 if (K.isText()) 290 Flags |= ELF::SHF_EXECINSTR; 291 292 if (K.isWriteable() && !K.isReadOnlyWithRel()) 293 Flags |= ELF::SHF_WRITE; 294 295 if (K.isThreadLocal()) 296 Flags |= ELF::SHF_TLS; 297 298 // K.isMergeableConst() is left out to honour PR4650 299 if (K.isMergeableCString() || K.isMergeableConst4() || 300 K.isMergeableConst8() || K.isMergeableConst16()) 301 Flags |= ELF::SHF_MERGE; 302 303 if (K.isMergeableCString()) 304 Flags |= ELF::SHF_STRINGS; 305 306 return Flags; 307 } 308 309 310 const MCSection *TargetLoweringObjectFileELF:: 311 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 312 Mangler *Mang, const TargetMachine &TM) const { 313 StringRef SectionName = GV->getSection(); 314 315 // Infer section flags from the section name if we can. 316 Kind = getELFKindForNamedSection(SectionName, Kind); 317 318 return getContext().getELFSection(SectionName, 319 getELFSectionType(SectionName, Kind), 320 getELFSectionFlags(Kind), Kind); 321 } 322 323 /// getSectionPrefixForGlobal - Return the section prefix name used by options 324 /// FunctionsSections and DataSections. 325 static const char *getSectionPrefixForGlobal(SectionKind Kind) { 326 if (Kind.isText()) return ".text."; 327 if (Kind.isReadOnly()) return ".rodata."; 328 329 if (Kind.isThreadData()) return ".tdata."; 330 if (Kind.isThreadBSS()) return ".tbss."; 331 332 if (Kind.isDataNoRel()) return ".data."; 333 if (Kind.isDataRelLocal()) return ".data.rel.local."; 334 if (Kind.isDataRel()) return ".data.rel."; 335 if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local."; 336 337 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 338 return ".data.rel.ro."; 339 } 340 341 342 const MCSection *TargetLoweringObjectFileELF:: 343 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 344 Mangler *Mang, const TargetMachine &TM) const { 345 // If we have -ffunction-section or -fdata-section then we should emit the 346 // global value to a uniqued section specifically for it. 347 bool EmitUniquedSection; 348 if (Kind.isText()) 349 EmitUniquedSection = TM.getFunctionSections(); 350 else 351 EmitUniquedSection = TM.getDataSections(); 352 353 // If this global is linkonce/weak and the target handles this by emitting it 354 // into a 'uniqued' section name, create and return the section now. 355 if ((GV->isWeakForLinker() || EmitUniquedSection) && 356 !Kind.isCommon() && !Kind.isBSS()) { 357 const char *Prefix; 358 Prefix = getSectionPrefixForGlobal(Kind); 359 360 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 361 MCSymbol *Sym = Mang->getSymbol(GV); 362 Name.append(Sym->getName().begin(), Sym->getName().end()); 363 StringRef Group = ""; 364 unsigned Flags = getELFSectionFlags(Kind); 365 if (GV->isWeakForLinker()) { 366 Group = Sym->getName(); 367 Flags |= ELF::SHF_GROUP; 368 } 369 370 return getContext().getELFSection(Name.str(), 371 getELFSectionType(Name.str(), Kind), 372 Flags, Kind, 0, Group); 373 } 374 375 if (Kind.isText()) return TextSection; 376 377 if (Kind.isMergeable1ByteCString() || 378 Kind.isMergeable2ByteCString() || 379 Kind.isMergeable4ByteCString()) { 380 381 // We also need alignment here. 382 // FIXME: this is getting the alignment of the character, not the 383 // alignment of the global! 384 unsigned Align = 385 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)); 386 387 const char *SizeSpec = ".rodata.str1."; 388 if (Kind.isMergeable2ByteCString()) 389 SizeSpec = ".rodata.str2."; 390 else if (Kind.isMergeable4ByteCString()) 391 SizeSpec = ".rodata.str4."; 392 else 393 assert(Kind.isMergeable1ByteCString() && "unknown string width"); 394 395 396 std::string Name = SizeSpec + utostr(Align); 397 return getContext().getELFSection(Name, ELF::SHT_PROGBITS, 398 ELF::SHF_ALLOC | 399 ELF::SHF_MERGE | 400 ELF::SHF_STRINGS, 401 Kind); 402 } 403 404 if (Kind.isMergeableConst()) { 405 if (Kind.isMergeableConst4() && MergeableConst4Section) 406 return MergeableConst4Section; 407 if (Kind.isMergeableConst8() && MergeableConst8Section) 408 return MergeableConst8Section; 409 if (Kind.isMergeableConst16() && MergeableConst16Section) 410 return MergeableConst16Section; 411 return ReadOnlySection; // .const 412 } 413 414 if (Kind.isReadOnly()) return ReadOnlySection; 415 416 if (Kind.isThreadData()) return TLSDataSection; 417 if (Kind.isThreadBSS()) return TLSBSSSection; 418 419 // Note: we claim that common symbols are put in BSSSection, but they are 420 // really emitted with the magic .comm directive, which creates a symbol table 421 // entry but not a section. 422 if (Kind.isBSS() || Kind.isCommon()) return BSSSection; 423 424 if (Kind.isDataNoRel()) return DataSection; 425 if (Kind.isDataRelLocal()) return DataRelLocalSection; 426 if (Kind.isDataRel()) return DataRelSection; 427 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 428 429 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 430 return DataRelROSection; 431 } 432 433 /// getSectionForConstant - Given a mergeable constant with the 434 /// specified size and relocation information, return a section that it 435 /// should be placed in. 436 const MCSection *TargetLoweringObjectFileELF:: 437 getSectionForConstant(SectionKind Kind) const { 438 if (Kind.isMergeableConst4() && MergeableConst4Section) 439 return MergeableConst4Section; 440 if (Kind.isMergeableConst8() && MergeableConst8Section) 441 return MergeableConst8Section; 442 if (Kind.isMergeableConst16() && MergeableConst16Section) 443 return MergeableConst16Section; 444 if (Kind.isReadOnly()) 445 return ReadOnlySection; 446 447 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 448 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 449 return DataRelROSection; 450 } 451 452 const MCExpr *TargetLoweringObjectFileELF:: 453 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 454 MachineModuleInfo *MMI, 455 unsigned Encoding, MCStreamer &Streamer) const { 456 457 if (Encoding & dwarf::DW_EH_PE_indirect) { 458 MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>(); 459 460 SmallString<128> Name; 461 Mang->getNameWithPrefix(Name, GV, true); 462 Name += ".DW.stub"; 463 464 // Add information about the stub reference to ELFMMI so that the stub 465 // gets emitted by the asmprinter. 466 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); 467 MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym); 468 if (StubSym.getPointer() == 0) { 469 MCSymbol *Sym = Mang->getSymbol(GV); 470 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 471 } 472 473 return TargetLoweringObjectFile:: 474 getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 475 } 476 477 return TargetLoweringObjectFile:: 478 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); 479 } 480 481 //===----------------------------------------------------------------------===// 482 // MachO 483 //===----------------------------------------------------------------------===// 484 485 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx, 486 const TargetMachine &TM) { 487 IsFunctionEHFrameSymbolPrivate = false; 488 SupportsWeakOmittedEHFrame = false; 489 490 // .comm doesn't support alignment before Leopard. 491 Triple T(((LLVMTargetMachine&)TM).getTargetTriple()); 492 if (T.isMacOSX() && T.isMacOSXVersionLT(10, 5)) 493 CommDirectiveSupportsAlignment = false; 494 495 TargetLoweringObjectFile::Initialize(Ctx, TM); 496 497 TextSection // .text 498 = getContext().getMachOSection("__TEXT", "__text", 499 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 500 SectionKind::getText()); 501 DataSection // .data 502 = getContext().getMachOSection("__DATA", "__data", 0, 503 SectionKind::getDataRel()); 504 505 TLSDataSection // .tdata 506 = getContext().getMachOSection("__DATA", "__thread_data", 507 MCSectionMachO::S_THREAD_LOCAL_REGULAR, 508 SectionKind::getDataRel()); 509 TLSBSSSection // .tbss 510 = getContext().getMachOSection("__DATA", "__thread_bss", 511 MCSectionMachO::S_THREAD_LOCAL_ZEROFILL, 512 SectionKind::getThreadBSS()); 513 514 // TODO: Verify datarel below. 515 TLSTLVSection // .tlv 516 = getContext().getMachOSection("__DATA", "__thread_vars", 517 MCSectionMachO::S_THREAD_LOCAL_VARIABLES, 518 SectionKind::getDataRel()); 519 520 TLSThreadInitSection 521 = getContext().getMachOSection("__DATA", "__thread_init", 522 MCSectionMachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS, 523 SectionKind::getDataRel()); 524 525 CStringSection // .cstring 526 = getContext().getMachOSection("__TEXT", "__cstring", 527 MCSectionMachO::S_CSTRING_LITERALS, 528 SectionKind::getMergeable1ByteCString()); 529 UStringSection 530 = getContext().getMachOSection("__TEXT","__ustring", 0, 531 SectionKind::getMergeable2ByteCString()); 532 FourByteConstantSection // .literal4 533 = getContext().getMachOSection("__TEXT", "__literal4", 534 MCSectionMachO::S_4BYTE_LITERALS, 535 SectionKind::getMergeableConst4()); 536 EightByteConstantSection // .literal8 537 = getContext().getMachOSection("__TEXT", "__literal8", 538 MCSectionMachO::S_8BYTE_LITERALS, 539 SectionKind::getMergeableConst8()); 540 541 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back 542 // to using it in -static mode. 543 SixteenByteConstantSection = 0; 544 if (TM.getRelocationModel() != Reloc::Static && 545 TM.getTargetData()->getPointerSize() == 32) 546 SixteenByteConstantSection = // .literal16 547 getContext().getMachOSection("__TEXT", "__literal16", 548 MCSectionMachO::S_16BYTE_LITERALS, 549 SectionKind::getMergeableConst16()); 550 551 ReadOnlySection // .const 552 = getContext().getMachOSection("__TEXT", "__const", 0, 553 SectionKind::getReadOnly()); 554 555 TextCoalSection 556 = getContext().getMachOSection("__TEXT", "__textcoal_nt", 557 MCSectionMachO::S_COALESCED | 558 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 559 SectionKind::getText()); 560 ConstTextCoalSection 561 = getContext().getMachOSection("__TEXT", "__const_coal", 562 MCSectionMachO::S_COALESCED, 563 SectionKind::getReadOnly()); 564 ConstDataSection // .const_data 565 = getContext().getMachOSection("__DATA", "__const", 0, 566 SectionKind::getReadOnlyWithRel()); 567 DataCoalSection 568 = getContext().getMachOSection("__DATA","__datacoal_nt", 569 MCSectionMachO::S_COALESCED, 570 SectionKind::getDataRel()); 571 DataCommonSection 572 = getContext().getMachOSection("__DATA","__common", 573 MCSectionMachO::S_ZEROFILL, 574 SectionKind::getBSS()); 575 DataBSSSection 576 = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL, 577 SectionKind::getBSS()); 578 579 580 LazySymbolPointerSection 581 = getContext().getMachOSection("__DATA", "__la_symbol_ptr", 582 MCSectionMachO::S_LAZY_SYMBOL_POINTERS, 583 SectionKind::getMetadata()); 584 NonLazySymbolPointerSection 585 = getContext().getMachOSection("__DATA", "__nl_symbol_ptr", 586 MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS, 587 SectionKind::getMetadata()); 588 589 if (TM.getRelocationModel() == Reloc::Static) { 590 StaticCtorSection 591 = getContext().getMachOSection("__TEXT", "__constructor", 0, 592 SectionKind::getDataRel()); 593 StaticDtorSection 594 = getContext().getMachOSection("__TEXT", "__destructor", 0, 595 SectionKind::getDataRel()); 596 } else { 597 StaticCtorSection 598 = getContext().getMachOSection("__DATA", "__mod_init_func", 599 MCSectionMachO::S_MOD_INIT_FUNC_POINTERS, 600 SectionKind::getDataRel()); 601 StaticDtorSection 602 = getContext().getMachOSection("__DATA", "__mod_term_func", 603 MCSectionMachO::S_MOD_TERM_FUNC_POINTERS, 604 SectionKind::getDataRel()); 605 } 606 607 // Exception Handling. 608 LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0, 609 SectionKind::getReadOnlyWithRel()); 610 // Debug Information. 611 DwarfAbbrevSection = 612 getContext().getMachOSection("__DWARF", "__debug_abbrev", 613 MCSectionMachO::S_ATTR_DEBUG, 614 SectionKind::getMetadata()); 615 DwarfInfoSection = 616 getContext().getMachOSection("__DWARF", "__debug_info", 617 MCSectionMachO::S_ATTR_DEBUG, 618 SectionKind::getMetadata()); 619 DwarfLineSection = 620 getContext().getMachOSection("__DWARF", "__debug_line", 621 MCSectionMachO::S_ATTR_DEBUG, 622 SectionKind::getMetadata()); 623 DwarfFrameSection = 624 getContext().getMachOSection("__DWARF", "__debug_frame", 625 MCSectionMachO::S_ATTR_DEBUG, 626 SectionKind::getMetadata()); 627 DwarfPubNamesSection = 628 getContext().getMachOSection("__DWARF", "__debug_pubnames", 629 MCSectionMachO::S_ATTR_DEBUG, 630 SectionKind::getMetadata()); 631 DwarfPubTypesSection = 632 getContext().getMachOSection("__DWARF", "__debug_pubtypes", 633 MCSectionMachO::S_ATTR_DEBUG, 634 SectionKind::getMetadata()); 635 DwarfStrSection = 636 getContext().getMachOSection("__DWARF", "__debug_str", 637 MCSectionMachO::S_ATTR_DEBUG, 638 SectionKind::getMetadata()); 639 DwarfLocSection = 640 getContext().getMachOSection("__DWARF", "__debug_loc", 641 MCSectionMachO::S_ATTR_DEBUG, 642 SectionKind::getMetadata()); 643 DwarfARangesSection = 644 getContext().getMachOSection("__DWARF", "__debug_aranges", 645 MCSectionMachO::S_ATTR_DEBUG, 646 SectionKind::getMetadata()); 647 DwarfRangesSection = 648 getContext().getMachOSection("__DWARF", "__debug_ranges", 649 MCSectionMachO::S_ATTR_DEBUG, 650 SectionKind::getMetadata()); 651 DwarfMacroInfoSection = 652 getContext().getMachOSection("__DWARF", "__debug_macinfo", 653 MCSectionMachO::S_ATTR_DEBUG, 654 SectionKind::getMetadata()); 655 DwarfDebugInlineSection = 656 getContext().getMachOSection("__DWARF", "__debug_inlined", 657 MCSectionMachO::S_ATTR_DEBUG, 658 SectionKind::getMetadata()); 659 660 TLSExtraDataSection = TLSTLVSection; 661 } 662 663 const MCSection *TargetLoweringObjectFileMachO::getEHFrameSection() const { 664 return getContext().getMachOSection("__TEXT", "__eh_frame", 665 MCSectionMachO::S_COALESCED | 666 MCSectionMachO::S_ATTR_NO_TOC | 667 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS | 668 MCSectionMachO::S_ATTR_LIVE_SUPPORT, 669 SectionKind::getReadOnly()); 670 } 671 672 const MCSection *TargetLoweringObjectFileMachO:: 673 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 674 Mangler *Mang, const TargetMachine &TM) const { 675 // Parse the section specifier and create it if valid. 676 StringRef Segment, Section; 677 unsigned TAA = 0, StubSize = 0; 678 bool TAAParsed; 679 std::string ErrorCode = 680 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, 681 TAA, TAAParsed, StubSize); 682 if (!ErrorCode.empty()) { 683 // If invalid, report the error with report_fatal_error. 684 report_fatal_error("Global variable '" + GV->getNameStr() + 685 "' has an invalid section specifier '" + GV->getSection()+ 686 "': " + ErrorCode + "."); 687 // Fall back to dropping it into the data section. 688 return DataSection; 689 } 690 691 // Get the section. 692 const MCSectionMachO *S = 693 getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind); 694 695 // If TAA wasn't set by ParseSectionSpecifier() above, 696 // use the value returned by getMachOSection() as a default. 697 if (!TAAParsed) 698 TAA = S->getTypeAndAttributes(); 699 700 // Okay, now that we got the section, verify that the TAA & StubSize agree. 701 // If the user declared multiple globals with different section flags, we need 702 // to reject it here. 703 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) { 704 // If invalid, report the error with report_fatal_error. 705 report_fatal_error("Global variable '" + GV->getNameStr() + 706 "' section type or attributes does not match previous" 707 " section specifier"); 708 } 709 710 return S; 711 } 712 713 const MCSection *TargetLoweringObjectFileMachO:: 714 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 715 Mangler *Mang, const TargetMachine &TM) const { 716 717 // Handle thread local data. 718 if (Kind.isThreadBSS()) return TLSBSSSection; 719 if (Kind.isThreadData()) return TLSDataSection; 720 721 if (Kind.isText()) 722 return GV->isWeakForLinker() ? TextCoalSection : TextSection; 723 724 // If this is weak/linkonce, put this in a coalescable section, either in text 725 // or data depending on if it is writable. 726 if (GV->isWeakForLinker()) { 727 if (Kind.isReadOnly()) 728 return ConstTextCoalSection; 729 return DataCoalSection; 730 } 731 732 // FIXME: Alignment check should be handled by section classifier. 733 if (Kind.isMergeable1ByteCString() && 734 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 735 return CStringSection; 736 737 // Do not put 16-bit arrays in the UString section if they have an 738 // externally visible label, this runs into issues with certain linker 739 // versions. 740 if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() && 741 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 742 return UStringSection; 743 744 if (Kind.isMergeableConst()) { 745 if (Kind.isMergeableConst4()) 746 return FourByteConstantSection; 747 if (Kind.isMergeableConst8()) 748 return EightByteConstantSection; 749 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 750 return SixteenByteConstantSection; 751 } 752 753 // Otherwise, if it is readonly, but not something we can specially optimize, 754 // just drop it in .const. 755 if (Kind.isReadOnly()) 756 return ReadOnlySection; 757 758 // If this is marked const, put it into a const section. But if the dynamic 759 // linker needs to write to it, put it in the data segment. 760 if (Kind.isReadOnlyWithRel()) 761 return ConstDataSection; 762 763 // Put zero initialized globals with strong external linkage in the 764 // DATA, __common section with the .zerofill directive. 765 if (Kind.isBSSExtern()) 766 return DataCommonSection; 767 768 // Put zero initialized globals with local linkage in __DATA,__bss directive 769 // with the .zerofill directive (aka .lcomm). 770 if (Kind.isBSSLocal()) 771 return DataBSSSection; 772 773 // Otherwise, just drop the variable in the normal data section. 774 return DataSection; 775 } 776 777 const MCSection * 778 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { 779 // If this constant requires a relocation, we have to put it in the data 780 // segment, not in the text segment. 781 if (Kind.isDataRel() || Kind.isReadOnlyWithRel()) 782 return ConstDataSection; 783 784 if (Kind.isMergeableConst4()) 785 return FourByteConstantSection; 786 if (Kind.isMergeableConst8()) 787 return EightByteConstantSection; 788 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 789 return SixteenByteConstantSection; 790 return ReadOnlySection; // .const 791 } 792 793 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide 794 /// not to emit the UsedDirective for some symbols in llvm.used. 795 // FIXME: REMOVE this (rdar://7071300) 796 bool TargetLoweringObjectFileMachO:: 797 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { 798 /// On Darwin, internally linked data beginning with "L" or "l" does not have 799 /// the directive emitted (this occurs in ObjC metadata). 800 if (!GV) return false; 801 802 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. 803 if (GV->hasLocalLinkage() && !isa<Function>(GV)) { 804 // FIXME: ObjC metadata is currently emitted as internal symbols that have 805 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and 806 // this horrible hack can go away. 807 MCSymbol *Sym = Mang->getSymbol(GV); 808 if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l') 809 return false; 810 } 811 812 return true; 813 } 814 815 const MCExpr *TargetLoweringObjectFileMachO:: 816 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 817 MachineModuleInfo *MMI, unsigned Encoding, 818 MCStreamer &Streamer) const { 819 // The mach-o version of this method defaults to returning a stub reference. 820 821 if (Encoding & DW_EH_PE_indirect) { 822 MachineModuleInfoMachO &MachOMMI = 823 MMI->getObjFileInfo<MachineModuleInfoMachO>(); 824 825 SmallString<128> Name; 826 Mang->getNameWithPrefix(Name, GV, true); 827 Name += "$non_lazy_ptr"; 828 829 // Add information about the stub reference to MachOMMI so that the stub 830 // gets emitted by the asmprinter. 831 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); 832 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym); 833 if (StubSym.getPointer() == 0) { 834 MCSymbol *Sym = Mang->getSymbol(GV); 835 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 836 } 837 838 return TargetLoweringObjectFile:: 839 getExprForDwarfReference(SSym, Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 840 } 841 842 return TargetLoweringObjectFile:: 843 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); 844 } 845 846 MCSymbol *TargetLoweringObjectFileMachO:: 847 getCFIPersonalitySymbol(const GlobalValue *GV, Mangler *Mang, 848 MachineModuleInfo *MMI) const { 849 // The mach-o version of this method defaults to returning a stub reference. 850 MachineModuleInfoMachO &MachOMMI = 851 MMI->getObjFileInfo<MachineModuleInfoMachO>(); 852 853 SmallString<128> Name; 854 Mang->getNameWithPrefix(Name, GV, true); 855 Name += "$non_lazy_ptr"; 856 857 // Add information about the stub reference to MachOMMI so that the stub 858 // gets emitted by the asmprinter. 859 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); 860 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym); 861 if (StubSym.getPointer() == 0) { 862 MCSymbol *Sym = Mang->getSymbol(GV); 863 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 864 } 865 866 return SSym; 867 } 868 869 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const { 870 return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4; 871 } 872 873 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const { 874 return DW_EH_PE_pcrel; 875 } 876 877 unsigned TargetLoweringObjectFileMachO::getFDEEncoding(bool CFI) const { 878 return DW_EH_PE_pcrel; 879 } 880 881 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const { 882 return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4; 883 } 884 885 //===----------------------------------------------------------------------===// 886 // COFF 887 //===----------------------------------------------------------------------===// 888 889 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx, 890 const TargetMachine &TM) { 891 TargetLoweringObjectFile::Initialize(Ctx, TM); 892 TextSection = 893 getContext().getCOFFSection(".text", 894 COFF::IMAGE_SCN_CNT_CODE | 895 COFF::IMAGE_SCN_MEM_EXECUTE | 896 COFF::IMAGE_SCN_MEM_READ, 897 SectionKind::getText()); 898 DataSection = 899 getContext().getCOFFSection(".data", 900 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 901 COFF::IMAGE_SCN_MEM_READ | 902 COFF::IMAGE_SCN_MEM_WRITE, 903 SectionKind::getDataRel()); 904 ReadOnlySection = 905 getContext().getCOFFSection(".rdata", 906 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 907 COFF::IMAGE_SCN_MEM_READ, 908 SectionKind::getReadOnly()); 909 StaticCtorSection = 910 getContext().getCOFFSection(".ctors", 911 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 912 COFF::IMAGE_SCN_MEM_READ | 913 COFF::IMAGE_SCN_MEM_WRITE, 914 SectionKind::getDataRel()); 915 StaticDtorSection = 916 getContext().getCOFFSection(".dtors", 917 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 918 COFF::IMAGE_SCN_MEM_READ | 919 COFF::IMAGE_SCN_MEM_WRITE, 920 SectionKind::getDataRel()); 921 922 // FIXME: We're emitting LSDA info into a readonly section on COFF, even 923 // though it contains relocatable pointers. In PIC mode, this is probably a 924 // big runtime hit for C++ apps. Either the contents of the LSDA need to be 925 // adjusted or this should be a data section. 926 LSDASection = 927 getContext().getCOFFSection(".gcc_except_table", 928 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 929 COFF::IMAGE_SCN_MEM_READ, 930 SectionKind::getReadOnly()); 931 // Debug info. 932 DwarfAbbrevSection = 933 getContext().getCOFFSection(".debug_abbrev", 934 COFF::IMAGE_SCN_MEM_DISCARDABLE | 935 COFF::IMAGE_SCN_MEM_READ, 936 SectionKind::getMetadata()); 937 DwarfInfoSection = 938 getContext().getCOFFSection(".debug_info", 939 COFF::IMAGE_SCN_MEM_DISCARDABLE | 940 COFF::IMAGE_SCN_MEM_READ, 941 SectionKind::getMetadata()); 942 DwarfLineSection = 943 getContext().getCOFFSection(".debug_line", 944 COFF::IMAGE_SCN_MEM_DISCARDABLE | 945 COFF::IMAGE_SCN_MEM_READ, 946 SectionKind::getMetadata()); 947 DwarfFrameSection = 948 getContext().getCOFFSection(".debug_frame", 949 COFF::IMAGE_SCN_MEM_DISCARDABLE | 950 COFF::IMAGE_SCN_MEM_READ, 951 SectionKind::getMetadata()); 952 DwarfPubNamesSection = 953 getContext().getCOFFSection(".debug_pubnames", 954 COFF::IMAGE_SCN_MEM_DISCARDABLE | 955 COFF::IMAGE_SCN_MEM_READ, 956 SectionKind::getMetadata()); 957 DwarfPubTypesSection = 958 getContext().getCOFFSection(".debug_pubtypes", 959 COFF::IMAGE_SCN_MEM_DISCARDABLE | 960 COFF::IMAGE_SCN_MEM_READ, 961 SectionKind::getMetadata()); 962 DwarfStrSection = 963 getContext().getCOFFSection(".debug_str", 964 COFF::IMAGE_SCN_MEM_DISCARDABLE | 965 COFF::IMAGE_SCN_MEM_READ, 966 SectionKind::getMetadata()); 967 DwarfLocSection = 968 getContext().getCOFFSection(".debug_loc", 969 COFF::IMAGE_SCN_MEM_DISCARDABLE | 970 COFF::IMAGE_SCN_MEM_READ, 971 SectionKind::getMetadata()); 972 DwarfARangesSection = 973 getContext().getCOFFSection(".debug_aranges", 974 COFF::IMAGE_SCN_MEM_DISCARDABLE | 975 COFF::IMAGE_SCN_MEM_READ, 976 SectionKind::getMetadata()); 977 DwarfRangesSection = 978 getContext().getCOFFSection(".debug_ranges", 979 COFF::IMAGE_SCN_MEM_DISCARDABLE | 980 COFF::IMAGE_SCN_MEM_READ, 981 SectionKind::getMetadata()); 982 DwarfMacroInfoSection = 983 getContext().getCOFFSection(".debug_macinfo", 984 COFF::IMAGE_SCN_MEM_DISCARDABLE | 985 COFF::IMAGE_SCN_MEM_READ, 986 SectionKind::getMetadata()); 987 988 DrectveSection = 989 getContext().getCOFFSection(".drectve", 990 COFF::IMAGE_SCN_LNK_INFO, 991 SectionKind::getMetadata()); 992 993 PDataSection = 994 getContext().getCOFFSection(".pdata", 995 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 996 COFF::IMAGE_SCN_MEM_READ | 997 COFF::IMAGE_SCN_MEM_WRITE, 998 SectionKind::getDataRel()); 999 1000 XDataSection = 1001 getContext().getCOFFSection(".xdata", 1002 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 1003 COFF::IMAGE_SCN_MEM_READ | 1004 COFF::IMAGE_SCN_MEM_WRITE, 1005 SectionKind::getDataRel()); 1006 } 1007 1008 const MCSection *TargetLoweringObjectFileCOFF::getEHFrameSection() const { 1009 return getContext().getCOFFSection(".eh_frame", 1010 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 1011 COFF::IMAGE_SCN_MEM_READ | 1012 COFF::IMAGE_SCN_MEM_WRITE, 1013 SectionKind::getDataRel()); 1014 } 1015 1016 1017 static unsigned 1018 getCOFFSectionFlags(SectionKind K) { 1019 unsigned Flags = 0; 1020 1021 if (K.isMetadata()) 1022 Flags |= 1023 COFF::IMAGE_SCN_MEM_DISCARDABLE; 1024 else if (K.isText()) 1025 Flags |= 1026 COFF::IMAGE_SCN_MEM_EXECUTE | 1027 COFF::IMAGE_SCN_MEM_READ | 1028 COFF::IMAGE_SCN_CNT_CODE; 1029 else if (K.isBSS ()) 1030 Flags |= 1031 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA | 1032 COFF::IMAGE_SCN_MEM_READ | 1033 COFF::IMAGE_SCN_MEM_WRITE; 1034 else if (K.isReadOnly()) 1035 Flags |= 1036 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 1037 COFF::IMAGE_SCN_MEM_READ; 1038 else if (K.isWriteable()) 1039 Flags |= 1040 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 1041 COFF::IMAGE_SCN_MEM_READ | 1042 COFF::IMAGE_SCN_MEM_WRITE; 1043 1044 return Flags; 1045 } 1046 1047 const MCSection *TargetLoweringObjectFileCOFF:: 1048 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 1049 Mangler *Mang, const TargetMachine &TM) const { 1050 return getContext().getCOFFSection(GV->getSection(), 1051 getCOFFSectionFlags(Kind), 1052 Kind); 1053 } 1054 1055 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { 1056 if (Kind.isText()) 1057 return ".text$"; 1058 if (Kind.isBSS ()) 1059 return ".bss$"; 1060 if (Kind.isWriteable()) 1061 return ".data$"; 1062 return ".rdata$"; 1063 } 1064 1065 1066 const MCSection *TargetLoweringObjectFileCOFF:: 1067 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 1068 Mangler *Mang, const TargetMachine &TM) const { 1069 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 1070 1071 // If this global is linkonce/weak and the target handles this by emitting it 1072 // into a 'uniqued' section name, create and return the section now. 1073 if (GV->isWeakForLinker()) { 1074 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); 1075 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 1076 MCSymbol *Sym = Mang->getSymbol(GV); 1077 Name.append(Sym->getName().begin() + 1, Sym->getName().end()); 1078 1079 unsigned Characteristics = getCOFFSectionFlags(Kind); 1080 1081 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT; 1082 1083 return getContext().getCOFFSection(Name.str(), Characteristics, 1084 COFF::IMAGE_COMDAT_SELECT_ANY, Kind); 1085 } 1086 1087 if (Kind.isText()) 1088 return getTextSection(); 1089 1090 return getDataSection(); 1091 } 1092 1093