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::getPersonalityPICSymbol(StringRef Name) const { 182 Twine FullName = StringRef("DW.ref.") + Name; 183 return getContext().GetOrCreateSymbol(FullName); 184 } 185 186 void TargetLoweringObjectFileELF::emitPersonalityValue(MCStreamer &Streamer, 187 const TargetMachine &TM, 188 const MCSymbol *Sym) const { 189 MCSymbol *Label = getPersonalityPICSymbol(Sym->getName()); 190 Streamer.EmitSymbolAttribute(Label, MCSA_Hidden); 191 Streamer.EmitSymbolAttribute(Label, MCSA_Weak); 192 Twine SectionName = StringRef(".data.") + Label->getName(); 193 SmallString<64> NameData; 194 SectionName.toVector(NameData); 195 unsigned Flags = ELF::SHF_ALLOC | ELF::SHF_WRITE | ELF::SHF_GROUP; 196 const MCSection *Sec = getContext().getELFSection(NameData, 197 ELF::SHT_PROGBITS, 198 Flags, 199 SectionKind::getDataRel(), 200 0, Label->getName()); 201 Streamer.SwitchSection(Sec); 202 Streamer.EmitValueToAlignment(8); 203 Streamer.EmitSymbolAttribute(Label, MCSA_ELF_TypeObject); 204 const MCExpr *E = MCConstantExpr::Create(8, getContext()); 205 Streamer.EmitELFSize(Label, E); 206 Streamer.EmitLabel(Label); 207 208 unsigned Size = TM.getTargetData()->getPointerSize(); 209 Streamer.EmitSymbolValue(Sym, Size); 210 } 211 212 static SectionKind 213 getELFKindForNamedSection(StringRef Name, SectionKind K) { 214 // FIXME: Why is this here? Codegen is should not be in the business 215 // of figuring section flags. If the user wrote section(".eh_frame"), 216 // we should just pass that to MC which will defer to the assembly 217 // or use its default if producing an object file. 218 if (Name.empty() || Name[0] != '.') return K; 219 220 // Some lame default implementation based on some magic section names. 221 if (Name == ".bss" || 222 Name.startswith(".bss.") || 223 Name.startswith(".gnu.linkonce.b.") || 224 Name.startswith(".llvm.linkonce.b.") || 225 Name == ".sbss" || 226 Name.startswith(".sbss.") || 227 Name.startswith(".gnu.linkonce.sb.") || 228 Name.startswith(".llvm.linkonce.sb.")) 229 return SectionKind::getBSS(); 230 231 if (Name == ".tdata" || 232 Name.startswith(".tdata.") || 233 Name.startswith(".gnu.linkonce.td.") || 234 Name.startswith(".llvm.linkonce.td.")) 235 return SectionKind::getThreadData(); 236 237 if (Name == ".tbss" || 238 Name.startswith(".tbss.") || 239 Name.startswith(".gnu.linkonce.tb.") || 240 Name.startswith(".llvm.linkonce.tb.")) 241 return SectionKind::getThreadBSS(); 242 243 if (Name == ".eh_frame") 244 return SectionKind::getDataRel(); 245 246 return K; 247 } 248 249 250 static unsigned getELFSectionType(StringRef Name, SectionKind K) { 251 252 if (Name == ".init_array") 253 return ELF::SHT_INIT_ARRAY; 254 255 if (Name == ".fini_array") 256 return ELF::SHT_FINI_ARRAY; 257 258 if (Name == ".preinit_array") 259 return ELF::SHT_PREINIT_ARRAY; 260 261 if (K.isBSS() || K.isThreadBSS()) 262 return ELF::SHT_NOBITS; 263 264 return ELF::SHT_PROGBITS; 265 } 266 267 268 static unsigned 269 getELFSectionFlags(SectionKind K) { 270 unsigned Flags = 0; 271 272 if (!K.isMetadata()) 273 Flags |= ELF::SHF_ALLOC; 274 275 if (K.isText()) 276 Flags |= ELF::SHF_EXECINSTR; 277 278 if (K.isWriteable()) 279 Flags |= ELF::SHF_WRITE; 280 281 if (K.isThreadLocal()) 282 Flags |= ELF::SHF_TLS; 283 284 // K.isMergeableConst() is left out to honour PR4650 285 if (K.isMergeableCString() || K.isMergeableConst4() || 286 K.isMergeableConst8() || K.isMergeableConst16()) 287 Flags |= ELF::SHF_MERGE; 288 289 if (K.isMergeableCString()) 290 Flags |= ELF::SHF_STRINGS; 291 292 return Flags; 293 } 294 295 296 const MCSection *TargetLoweringObjectFileELF:: 297 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 298 Mangler *Mang, const TargetMachine &TM) const { 299 StringRef SectionName = GV->getSection(); 300 301 // Infer section flags from the section name if we can. 302 Kind = getELFKindForNamedSection(SectionName, Kind); 303 304 return getContext().getELFSection(SectionName, 305 getELFSectionType(SectionName, Kind), 306 getELFSectionFlags(Kind), Kind); 307 } 308 309 /// getSectionPrefixForGlobal - Return the section prefix name used by options 310 /// FunctionsSections and DataSections. 311 static const char *getSectionPrefixForGlobal(SectionKind Kind) { 312 if (Kind.isText()) return ".text."; 313 if (Kind.isReadOnly()) return ".rodata."; 314 315 if (Kind.isThreadData()) return ".tdata."; 316 if (Kind.isThreadBSS()) return ".tbss."; 317 318 if (Kind.isDataNoRel()) return ".data."; 319 if (Kind.isDataRelLocal()) return ".data.rel.local."; 320 if (Kind.isDataRel()) return ".data.rel."; 321 if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local."; 322 323 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 324 return ".data.rel.ro."; 325 } 326 327 328 const MCSection *TargetLoweringObjectFileELF:: 329 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 330 Mangler *Mang, const TargetMachine &TM) const { 331 // If we have -ffunction-section or -fdata-section then we should emit the 332 // global value to a uniqued section specifically for it. 333 bool EmitUniquedSection; 334 if (Kind.isText()) 335 EmitUniquedSection = TM.getFunctionSections(); 336 else 337 EmitUniquedSection = TM.getDataSections(); 338 339 // If this global is linkonce/weak and the target handles this by emitting it 340 // into a 'uniqued' section name, create and return the section now. 341 if ((GV->isWeakForLinker() || EmitUniquedSection) && 342 !Kind.isCommon() && !Kind.isBSS()) { 343 const char *Prefix; 344 Prefix = getSectionPrefixForGlobal(Kind); 345 346 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 347 MCSymbol *Sym = Mang->getSymbol(GV); 348 Name.append(Sym->getName().begin(), Sym->getName().end()); 349 StringRef Group = ""; 350 unsigned Flags = getELFSectionFlags(Kind); 351 if (GV->isWeakForLinker()) { 352 Group = Sym->getName(); 353 Flags |= ELF::SHF_GROUP; 354 } 355 356 return getContext().getELFSection(Name.str(), 357 getELFSectionType(Name.str(), Kind), 358 Flags, Kind, 0, Group); 359 } 360 361 if (Kind.isText()) return TextSection; 362 363 if (Kind.isMergeable1ByteCString() || 364 Kind.isMergeable2ByteCString() || 365 Kind.isMergeable4ByteCString()) { 366 367 // We also need alignment here. 368 // FIXME: this is getting the alignment of the character, not the 369 // alignment of the global! 370 unsigned Align = 371 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)); 372 373 const char *SizeSpec = ".rodata.str1."; 374 if (Kind.isMergeable2ByteCString()) 375 SizeSpec = ".rodata.str2."; 376 else if (Kind.isMergeable4ByteCString()) 377 SizeSpec = ".rodata.str4."; 378 else 379 assert(Kind.isMergeable1ByteCString() && "unknown string width"); 380 381 382 std::string Name = SizeSpec + utostr(Align); 383 return getContext().getELFSection(Name, ELF::SHT_PROGBITS, 384 ELF::SHF_ALLOC | 385 ELF::SHF_MERGE | 386 ELF::SHF_STRINGS, 387 Kind); 388 } 389 390 if (Kind.isMergeableConst()) { 391 if (Kind.isMergeableConst4() && MergeableConst4Section) 392 return MergeableConst4Section; 393 if (Kind.isMergeableConst8() && MergeableConst8Section) 394 return MergeableConst8Section; 395 if (Kind.isMergeableConst16() && MergeableConst16Section) 396 return MergeableConst16Section; 397 return ReadOnlySection; // .const 398 } 399 400 if (Kind.isReadOnly()) return ReadOnlySection; 401 402 if (Kind.isThreadData()) return TLSDataSection; 403 if (Kind.isThreadBSS()) return TLSBSSSection; 404 405 // Note: we claim that common symbols are put in BSSSection, but they are 406 // really emitted with the magic .comm directive, which creates a symbol table 407 // entry but not a section. 408 if (Kind.isBSS() || Kind.isCommon()) return BSSSection; 409 410 if (Kind.isDataNoRel()) return DataSection; 411 if (Kind.isDataRelLocal()) return DataRelLocalSection; 412 if (Kind.isDataRel()) return DataRelSection; 413 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 414 415 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 416 return DataRelROSection; 417 } 418 419 /// getSectionForConstant - Given a mergeable constant with the 420 /// specified size and relocation information, return a section that it 421 /// should be placed in. 422 const MCSection *TargetLoweringObjectFileELF:: 423 getSectionForConstant(SectionKind Kind) const { 424 if (Kind.isMergeableConst4() && MergeableConst4Section) 425 return MergeableConst4Section; 426 if (Kind.isMergeableConst8() && MergeableConst8Section) 427 return MergeableConst8Section; 428 if (Kind.isMergeableConst16() && MergeableConst16Section) 429 return MergeableConst16Section; 430 if (Kind.isReadOnly()) 431 return ReadOnlySection; 432 433 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 434 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 435 return DataRelROSection; 436 } 437 438 const MCExpr *TargetLoweringObjectFileELF:: 439 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 440 MachineModuleInfo *MMI, 441 unsigned Encoding, MCStreamer &Streamer) const { 442 443 if (Encoding & dwarf::DW_EH_PE_indirect) { 444 MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>(); 445 446 SmallString<128> Name; 447 Mang->getNameWithPrefix(Name, GV, true); 448 Name += ".DW.stub"; 449 450 // Add information about the stub reference to ELFMMI so that the stub 451 // gets emitted by the asmprinter. 452 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); 453 MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym); 454 if (StubSym.getPointer() == 0) { 455 MCSymbol *Sym = Mang->getSymbol(GV); 456 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 457 } 458 459 return TargetLoweringObjectFile:: 460 getExprForDwarfReference(SSym, Mang, MMI, 461 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 462 } 463 464 return TargetLoweringObjectFile:: 465 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); 466 } 467 468 //===----------------------------------------------------------------------===// 469 // MachO 470 //===----------------------------------------------------------------------===// 471 472 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx, 473 const TargetMachine &TM) { 474 // _foo.eh symbols are currently always exported so that the linker knows 475 // about them. This is not necessary on 10.6 and later, but it 476 // doesn't hurt anything. 477 // FIXME: I need to get this from Triple. 478 IsFunctionEHSymbolGlobal = true; 479 IsFunctionEHFrameSymbolPrivate = false; 480 SupportsWeakOmittedEHFrame = false; 481 482 // .comm doesn't support alignment before Leopard. 483 Triple T(((LLVMTargetMachine&)TM).getTargetTriple()); 484 if (T.isMacOSX() && T.isMacOSXVersionLT(10, 5)) 485 CommDirectiveSupportsAlignment = false; 486 487 TargetLoweringObjectFile::Initialize(Ctx, TM); 488 489 TextSection // .text 490 = getContext().getMachOSection("__TEXT", "__text", 491 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 492 SectionKind::getText()); 493 DataSection // .data 494 = getContext().getMachOSection("__DATA", "__data", 0, 495 SectionKind::getDataRel()); 496 497 TLSDataSection // .tdata 498 = getContext().getMachOSection("__DATA", "__thread_data", 499 MCSectionMachO::S_THREAD_LOCAL_REGULAR, 500 SectionKind::getDataRel()); 501 TLSBSSSection // .tbss 502 = getContext().getMachOSection("__DATA", "__thread_bss", 503 MCSectionMachO::S_THREAD_LOCAL_ZEROFILL, 504 SectionKind::getThreadBSS()); 505 506 // TODO: Verify datarel below. 507 TLSTLVSection // .tlv 508 = getContext().getMachOSection("__DATA", "__thread_vars", 509 MCSectionMachO::S_THREAD_LOCAL_VARIABLES, 510 SectionKind::getDataRel()); 511 512 TLSThreadInitSection 513 = getContext().getMachOSection("__DATA", "__thread_init", 514 MCSectionMachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS, 515 SectionKind::getDataRel()); 516 517 CStringSection // .cstring 518 = getContext().getMachOSection("__TEXT", "__cstring", 519 MCSectionMachO::S_CSTRING_LITERALS, 520 SectionKind::getMergeable1ByteCString()); 521 UStringSection 522 = getContext().getMachOSection("__TEXT","__ustring", 0, 523 SectionKind::getMergeable2ByteCString()); 524 FourByteConstantSection // .literal4 525 = getContext().getMachOSection("__TEXT", "__literal4", 526 MCSectionMachO::S_4BYTE_LITERALS, 527 SectionKind::getMergeableConst4()); 528 EightByteConstantSection // .literal8 529 = getContext().getMachOSection("__TEXT", "__literal8", 530 MCSectionMachO::S_8BYTE_LITERALS, 531 SectionKind::getMergeableConst8()); 532 533 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back 534 // to using it in -static mode. 535 SixteenByteConstantSection = 0; 536 if (TM.getRelocationModel() != Reloc::Static && 537 TM.getTargetData()->getPointerSize() == 32) 538 SixteenByteConstantSection = // .literal16 539 getContext().getMachOSection("__TEXT", "__literal16", 540 MCSectionMachO::S_16BYTE_LITERALS, 541 SectionKind::getMergeableConst16()); 542 543 ReadOnlySection // .const 544 = getContext().getMachOSection("__TEXT", "__const", 0, 545 SectionKind::getReadOnly()); 546 547 TextCoalSection 548 = getContext().getMachOSection("__TEXT", "__textcoal_nt", 549 MCSectionMachO::S_COALESCED | 550 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 551 SectionKind::getText()); 552 ConstTextCoalSection 553 = getContext().getMachOSection("__TEXT", "__const_coal", 554 MCSectionMachO::S_COALESCED, 555 SectionKind::getReadOnly()); 556 ConstDataSection // .const_data 557 = getContext().getMachOSection("__DATA", "__const", 0, 558 SectionKind::getReadOnlyWithRel()); 559 DataCoalSection 560 = getContext().getMachOSection("__DATA","__datacoal_nt", 561 MCSectionMachO::S_COALESCED, 562 SectionKind::getDataRel()); 563 DataCommonSection 564 = getContext().getMachOSection("__DATA","__common", 565 MCSectionMachO::S_ZEROFILL, 566 SectionKind::getBSS()); 567 DataBSSSection 568 = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL, 569 SectionKind::getBSS()); 570 571 572 LazySymbolPointerSection 573 = getContext().getMachOSection("__DATA", "__la_symbol_ptr", 574 MCSectionMachO::S_LAZY_SYMBOL_POINTERS, 575 SectionKind::getMetadata()); 576 NonLazySymbolPointerSection 577 = getContext().getMachOSection("__DATA", "__nl_symbol_ptr", 578 MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS, 579 SectionKind::getMetadata()); 580 581 if (TM.getRelocationModel() == Reloc::Static) { 582 StaticCtorSection 583 = getContext().getMachOSection("__TEXT", "__constructor", 0, 584 SectionKind::getDataRel()); 585 StaticDtorSection 586 = getContext().getMachOSection("__TEXT", "__destructor", 0, 587 SectionKind::getDataRel()); 588 } else { 589 StaticCtorSection 590 = getContext().getMachOSection("__DATA", "__mod_init_func", 591 MCSectionMachO::S_MOD_INIT_FUNC_POINTERS, 592 SectionKind::getDataRel()); 593 StaticDtorSection 594 = getContext().getMachOSection("__DATA", "__mod_term_func", 595 MCSectionMachO::S_MOD_TERM_FUNC_POINTERS, 596 SectionKind::getDataRel()); 597 } 598 599 // Exception Handling. 600 LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0, 601 SectionKind::getReadOnlyWithRel()); 602 // Debug Information. 603 DwarfAbbrevSection = 604 getContext().getMachOSection("__DWARF", "__debug_abbrev", 605 MCSectionMachO::S_ATTR_DEBUG, 606 SectionKind::getMetadata()); 607 DwarfInfoSection = 608 getContext().getMachOSection("__DWARF", "__debug_info", 609 MCSectionMachO::S_ATTR_DEBUG, 610 SectionKind::getMetadata()); 611 DwarfLineSection = 612 getContext().getMachOSection("__DWARF", "__debug_line", 613 MCSectionMachO::S_ATTR_DEBUG, 614 SectionKind::getMetadata()); 615 DwarfFrameSection = 616 getContext().getMachOSection("__DWARF", "__debug_frame", 617 MCSectionMachO::S_ATTR_DEBUG, 618 SectionKind::getMetadata()); 619 DwarfPubNamesSection = 620 getContext().getMachOSection("__DWARF", "__debug_pubnames", 621 MCSectionMachO::S_ATTR_DEBUG, 622 SectionKind::getMetadata()); 623 DwarfPubTypesSection = 624 getContext().getMachOSection("__DWARF", "__debug_pubtypes", 625 MCSectionMachO::S_ATTR_DEBUG, 626 SectionKind::getMetadata()); 627 DwarfStrSection = 628 getContext().getMachOSection("__DWARF", "__debug_str", 629 MCSectionMachO::S_ATTR_DEBUG, 630 SectionKind::getMetadata()); 631 DwarfLocSection = 632 getContext().getMachOSection("__DWARF", "__debug_loc", 633 MCSectionMachO::S_ATTR_DEBUG, 634 SectionKind::getMetadata()); 635 DwarfARangesSection = 636 getContext().getMachOSection("__DWARF", "__debug_aranges", 637 MCSectionMachO::S_ATTR_DEBUG, 638 SectionKind::getMetadata()); 639 DwarfRangesSection = 640 getContext().getMachOSection("__DWARF", "__debug_ranges", 641 MCSectionMachO::S_ATTR_DEBUG, 642 SectionKind::getMetadata()); 643 DwarfMacroInfoSection = 644 getContext().getMachOSection("__DWARF", "__debug_macinfo", 645 MCSectionMachO::S_ATTR_DEBUG, 646 SectionKind::getMetadata()); 647 DwarfDebugInlineSection = 648 getContext().getMachOSection("__DWARF", "__debug_inlined", 649 MCSectionMachO::S_ATTR_DEBUG, 650 SectionKind::getMetadata()); 651 652 TLSExtraDataSection = TLSTLVSection; 653 } 654 655 const MCSection *TargetLoweringObjectFileMachO::getEHFrameSection() const { 656 return getContext().getMachOSection("__TEXT", "__eh_frame", 657 MCSectionMachO::S_COALESCED | 658 MCSectionMachO::S_ATTR_NO_TOC | 659 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS | 660 MCSectionMachO::S_ATTR_LIVE_SUPPORT, 661 SectionKind::getReadOnly()); 662 } 663 664 const MCSection *TargetLoweringObjectFileMachO:: 665 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 666 Mangler *Mang, const TargetMachine &TM) const { 667 // Parse the section specifier and create it if valid. 668 StringRef Segment, Section; 669 unsigned TAA = 0, StubSize = 0; 670 bool TAAParsed; 671 std::string ErrorCode = 672 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, 673 TAA, TAAParsed, StubSize); 674 if (!ErrorCode.empty()) { 675 // If invalid, report the error with report_fatal_error. 676 report_fatal_error("Global variable '" + GV->getNameStr() + 677 "' has an invalid section specifier '" + GV->getSection()+ 678 "': " + ErrorCode + "."); 679 // Fall back to dropping it into the data section. 680 return DataSection; 681 } 682 683 // Get the section. 684 const MCSectionMachO *S = 685 getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind); 686 687 // If TAA wasn't set by ParseSectionSpecifier() above, 688 // use the value returned by getMachOSection() as a default. 689 if (!TAAParsed) 690 TAA = S->getTypeAndAttributes(); 691 692 // Okay, now that we got the section, verify that the TAA & StubSize agree. 693 // If the user declared multiple globals with different section flags, we need 694 // to reject it here. 695 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) { 696 // If invalid, report the error with report_fatal_error. 697 report_fatal_error("Global variable '" + GV->getNameStr() + 698 "' section type or attributes does not match previous" 699 " section specifier"); 700 } 701 702 return S; 703 } 704 705 const MCSection *TargetLoweringObjectFileMachO:: 706 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 707 Mangler *Mang, const TargetMachine &TM) const { 708 709 // Handle thread local data. 710 if (Kind.isThreadBSS()) return TLSBSSSection; 711 if (Kind.isThreadData()) return TLSDataSection; 712 713 if (Kind.isText()) 714 return GV->isWeakForLinker() ? TextCoalSection : TextSection; 715 716 // If this is weak/linkonce, put this in a coalescable section, either in text 717 // or data depending on if it is writable. 718 if (GV->isWeakForLinker()) { 719 if (Kind.isReadOnly()) 720 return ConstTextCoalSection; 721 return DataCoalSection; 722 } 723 724 // FIXME: Alignment check should be handled by section classifier. 725 if (Kind.isMergeable1ByteCString() && 726 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 727 return CStringSection; 728 729 // Do not put 16-bit arrays in the UString section if they have an 730 // externally visible label, this runs into issues with certain linker 731 // versions. 732 if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() && 733 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 734 return UStringSection; 735 736 if (Kind.isMergeableConst()) { 737 if (Kind.isMergeableConst4()) 738 return FourByteConstantSection; 739 if (Kind.isMergeableConst8()) 740 return EightByteConstantSection; 741 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 742 return SixteenByteConstantSection; 743 } 744 745 // Otherwise, if it is readonly, but not something we can specially optimize, 746 // just drop it in .const. 747 if (Kind.isReadOnly()) 748 return ReadOnlySection; 749 750 // If this is marked const, put it into a const section. But if the dynamic 751 // linker needs to write to it, put it in the data segment. 752 if (Kind.isReadOnlyWithRel()) 753 return ConstDataSection; 754 755 // Put zero initialized globals with strong external linkage in the 756 // DATA, __common section with the .zerofill directive. 757 if (Kind.isBSSExtern()) 758 return DataCommonSection; 759 760 // Put zero initialized globals with local linkage in __DATA,__bss directive 761 // with the .zerofill directive (aka .lcomm). 762 if (Kind.isBSSLocal()) 763 return DataBSSSection; 764 765 // Otherwise, just drop the variable in the normal data section. 766 return DataSection; 767 } 768 769 const MCSection * 770 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { 771 // If this constant requires a relocation, we have to put it in the data 772 // segment, not in the text segment. 773 if (Kind.isDataRel() || Kind.isReadOnlyWithRel()) 774 return ConstDataSection; 775 776 if (Kind.isMergeableConst4()) 777 return FourByteConstantSection; 778 if (Kind.isMergeableConst8()) 779 return EightByteConstantSection; 780 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 781 return SixteenByteConstantSection; 782 return ReadOnlySection; // .const 783 } 784 785 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide 786 /// not to emit the UsedDirective for some symbols in llvm.used. 787 // FIXME: REMOVE this (rdar://7071300) 788 bool TargetLoweringObjectFileMachO:: 789 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { 790 /// On Darwin, internally linked data beginning with "L" or "l" does not have 791 /// the directive emitted (this occurs in ObjC metadata). 792 if (!GV) return false; 793 794 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. 795 if (GV->hasLocalLinkage() && !isa<Function>(GV)) { 796 // FIXME: ObjC metadata is currently emitted as internal symbols that have 797 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and 798 // this horrible hack can go away. 799 MCSymbol *Sym = Mang->getSymbol(GV); 800 if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l') 801 return false; 802 } 803 804 return true; 805 } 806 807 const MCExpr *TargetLoweringObjectFileMachO:: 808 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 809 MachineModuleInfo *MMI, unsigned Encoding, 810 MCStreamer &Streamer) const { 811 // The mach-o version of this method defaults to returning a stub reference. 812 813 if (Encoding & DW_EH_PE_indirect) { 814 MachineModuleInfoMachO &MachOMMI = 815 MMI->getObjFileInfo<MachineModuleInfoMachO>(); 816 817 SmallString<128> Name; 818 Mang->getNameWithPrefix(Name, GV, true); 819 Name += "$non_lazy_ptr"; 820 821 // Add information about the stub reference to MachOMMI so that the stub 822 // gets emitted by the asmprinter. 823 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); 824 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym); 825 if (StubSym.getPointer() == 0) { 826 MCSymbol *Sym = Mang->getSymbol(GV); 827 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 828 } 829 830 return TargetLoweringObjectFile:: 831 getExprForDwarfReference(SSym, Mang, MMI, 832 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 833 } 834 835 return TargetLoweringObjectFile:: 836 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); 837 } 838 839 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const { 840 return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4; 841 } 842 843 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const { 844 return DW_EH_PE_pcrel; 845 } 846 847 unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const { 848 return DW_EH_PE_pcrel; 849 } 850 851 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const { 852 return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4; 853 } 854 855 //===----------------------------------------------------------------------===// 856 // COFF 857 //===----------------------------------------------------------------------===// 858 859 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx, 860 const TargetMachine &TM) { 861 TargetLoweringObjectFile::Initialize(Ctx, TM); 862 TextSection = 863 getContext().getCOFFSection(".text", 864 COFF::IMAGE_SCN_CNT_CODE | 865 COFF::IMAGE_SCN_MEM_EXECUTE | 866 COFF::IMAGE_SCN_MEM_READ, 867 SectionKind::getText()); 868 DataSection = 869 getContext().getCOFFSection(".data", 870 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 871 COFF::IMAGE_SCN_MEM_READ | 872 COFF::IMAGE_SCN_MEM_WRITE, 873 SectionKind::getDataRel()); 874 ReadOnlySection = 875 getContext().getCOFFSection(".rdata", 876 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 877 COFF::IMAGE_SCN_MEM_READ, 878 SectionKind::getReadOnly()); 879 StaticCtorSection = 880 getContext().getCOFFSection(".ctors", 881 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 882 COFF::IMAGE_SCN_MEM_READ | 883 COFF::IMAGE_SCN_MEM_WRITE, 884 SectionKind::getDataRel()); 885 StaticDtorSection = 886 getContext().getCOFFSection(".dtors", 887 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 888 COFF::IMAGE_SCN_MEM_READ | 889 COFF::IMAGE_SCN_MEM_WRITE, 890 SectionKind::getDataRel()); 891 892 // FIXME: We're emitting LSDA info into a readonly section on COFF, even 893 // though it contains relocatable pointers. In PIC mode, this is probably a 894 // big runtime hit for C++ apps. Either the contents of the LSDA need to be 895 // adjusted or this should be a data section. 896 LSDASection = 897 getContext().getCOFFSection(".gcc_except_table", 898 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 899 COFF::IMAGE_SCN_MEM_READ, 900 SectionKind::getReadOnly()); 901 // Debug info. 902 DwarfAbbrevSection = 903 getContext().getCOFFSection(".debug_abbrev", 904 COFF::IMAGE_SCN_MEM_DISCARDABLE | 905 COFF::IMAGE_SCN_MEM_READ, 906 SectionKind::getMetadata()); 907 DwarfInfoSection = 908 getContext().getCOFFSection(".debug_info", 909 COFF::IMAGE_SCN_MEM_DISCARDABLE | 910 COFF::IMAGE_SCN_MEM_READ, 911 SectionKind::getMetadata()); 912 DwarfLineSection = 913 getContext().getCOFFSection(".debug_line", 914 COFF::IMAGE_SCN_MEM_DISCARDABLE | 915 COFF::IMAGE_SCN_MEM_READ, 916 SectionKind::getMetadata()); 917 DwarfFrameSection = 918 getContext().getCOFFSection(".debug_frame", 919 COFF::IMAGE_SCN_MEM_DISCARDABLE | 920 COFF::IMAGE_SCN_MEM_READ, 921 SectionKind::getMetadata()); 922 DwarfPubNamesSection = 923 getContext().getCOFFSection(".debug_pubnames", 924 COFF::IMAGE_SCN_MEM_DISCARDABLE | 925 COFF::IMAGE_SCN_MEM_READ, 926 SectionKind::getMetadata()); 927 DwarfPubTypesSection = 928 getContext().getCOFFSection(".debug_pubtypes", 929 COFF::IMAGE_SCN_MEM_DISCARDABLE | 930 COFF::IMAGE_SCN_MEM_READ, 931 SectionKind::getMetadata()); 932 DwarfStrSection = 933 getContext().getCOFFSection(".debug_str", 934 COFF::IMAGE_SCN_MEM_DISCARDABLE | 935 COFF::IMAGE_SCN_MEM_READ, 936 SectionKind::getMetadata()); 937 DwarfLocSection = 938 getContext().getCOFFSection(".debug_loc", 939 COFF::IMAGE_SCN_MEM_DISCARDABLE | 940 COFF::IMAGE_SCN_MEM_READ, 941 SectionKind::getMetadata()); 942 DwarfARangesSection = 943 getContext().getCOFFSection(".debug_aranges", 944 COFF::IMAGE_SCN_MEM_DISCARDABLE | 945 COFF::IMAGE_SCN_MEM_READ, 946 SectionKind::getMetadata()); 947 DwarfRangesSection = 948 getContext().getCOFFSection(".debug_ranges", 949 COFF::IMAGE_SCN_MEM_DISCARDABLE | 950 COFF::IMAGE_SCN_MEM_READ, 951 SectionKind::getMetadata()); 952 DwarfMacroInfoSection = 953 getContext().getCOFFSection(".debug_macinfo", 954 COFF::IMAGE_SCN_MEM_DISCARDABLE | 955 COFF::IMAGE_SCN_MEM_READ, 956 SectionKind::getMetadata()); 957 958 DrectveSection = 959 getContext().getCOFFSection(".drectve", 960 COFF::IMAGE_SCN_LNK_INFO, 961 SectionKind::getMetadata()); 962 } 963 964 const MCSection *TargetLoweringObjectFileCOFF::getEHFrameSection() const { 965 return getContext().getCOFFSection(".eh_frame", 966 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 967 COFF::IMAGE_SCN_MEM_READ | 968 COFF::IMAGE_SCN_MEM_WRITE, 969 SectionKind::getDataRel()); 970 } 971 972 973 static unsigned 974 getCOFFSectionFlags(SectionKind K) { 975 unsigned Flags = 0; 976 977 if (K.isMetadata()) 978 Flags |= 979 COFF::IMAGE_SCN_MEM_DISCARDABLE; 980 else if (K.isText()) 981 Flags |= 982 COFF::IMAGE_SCN_MEM_EXECUTE | 983 COFF::IMAGE_SCN_MEM_READ | 984 COFF::IMAGE_SCN_CNT_CODE; 985 else if (K.isBSS ()) 986 Flags |= 987 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA | 988 COFF::IMAGE_SCN_MEM_READ | 989 COFF::IMAGE_SCN_MEM_WRITE; 990 else if (K.isReadOnly()) 991 Flags |= 992 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 993 COFF::IMAGE_SCN_MEM_READ; 994 else if (K.isWriteable()) 995 Flags |= 996 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 997 COFF::IMAGE_SCN_MEM_READ | 998 COFF::IMAGE_SCN_MEM_WRITE; 999 1000 return Flags; 1001 } 1002 1003 const MCSection *TargetLoweringObjectFileCOFF:: 1004 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 1005 Mangler *Mang, const TargetMachine &TM) const { 1006 return getContext().getCOFFSection(GV->getSection(), 1007 getCOFFSectionFlags(Kind), 1008 Kind); 1009 } 1010 1011 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { 1012 if (Kind.isText()) 1013 return ".text$"; 1014 if (Kind.isBSS ()) 1015 return ".bss$"; 1016 if (Kind.isWriteable()) 1017 return ".data$"; 1018 return ".rdata$"; 1019 } 1020 1021 1022 const MCSection *TargetLoweringObjectFileCOFF:: 1023 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 1024 Mangler *Mang, const TargetMachine &TM) const { 1025 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 1026 1027 // If this global is linkonce/weak and the target handles this by emitting it 1028 // into a 'uniqued' section name, create and return the section now. 1029 if (GV->isWeakForLinker()) { 1030 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); 1031 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 1032 MCSymbol *Sym = Mang->getSymbol(GV); 1033 Name.append(Sym->getName().begin() + 1, Sym->getName().end()); 1034 1035 unsigned Characteristics = getCOFFSectionFlags(Kind); 1036 1037 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT; 1038 1039 return getContext().getCOFFSection(Name.str(), Characteristics, 1040 COFF::IMAGE_COMDAT_SELECT_ANY, Kind); 1041 } 1042 1043 if (Kind.isText()) 1044 return getTextSection(); 1045 1046 return getDataSection(); 1047 } 1048 1049