1 //===-- llvm/CodeGen/TargetLoweringObjectFileImpl.cpp - Object File Info --===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements classes used to handle lowerings specific to common 11 // object file formats. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "llvm/CodeGen/TargetLoweringObjectFileImpl.h" 16 #include "llvm/Constants.h" 17 #include "llvm/DerivedTypes.h" 18 #include "llvm/Function.h" 19 #include "llvm/GlobalVariable.h" 20 #include "llvm/CodeGen/MachineModuleInfoImpls.h" 21 #include "llvm/MC/MCContext.h" 22 #include "llvm/MC/MCExpr.h" 23 #include "llvm/MC/MCSectionMachO.h" 24 #include "llvm/MC/MCSectionELF.h" 25 #include "llvm/MC/MCSectionCOFF.h" 26 #include "llvm/MC/MCSymbol.h" 27 #include "llvm/Target/Mangler.h" 28 #include "llvm/Target/TargetData.h" 29 #include "llvm/Target/TargetMachine.h" 30 #include "llvm/Target/TargetOptions.h" 31 #include "llvm/Support/Dwarf.h" 32 #include "llvm/Support/ErrorHandling.h" 33 #include "llvm/Support/raw_ostream.h" 34 #include "llvm/ADT/SmallString.h" 35 #include "llvm/ADT/StringExtras.h" 36 #include "llvm/ADT/Triple.h" 37 using namespace llvm; 38 using namespace dwarf; 39 40 //===----------------------------------------------------------------------===// 41 // ELF 42 //===----------------------------------------------------------------------===// 43 44 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx, 45 const TargetMachine &TM) { 46 TargetLoweringObjectFile::Initialize(Ctx, TM); 47 48 BSSSection = 49 getContext().getELFSection(".bss", MCSectionELF::SHT_NOBITS, 50 MCSectionELF::SHF_WRITE |MCSectionELF::SHF_ALLOC, 51 SectionKind::getBSS()); 52 53 TextSection = 54 getContext().getELFSection(".text", MCSectionELF::SHT_PROGBITS, 55 MCSectionELF::SHF_EXECINSTR | 56 MCSectionELF::SHF_ALLOC, 57 SectionKind::getText()); 58 59 DataSection = 60 getContext().getELFSection(".data", MCSectionELF::SHT_PROGBITS, 61 MCSectionELF::SHF_WRITE |MCSectionELF::SHF_ALLOC, 62 SectionKind::getDataRel()); 63 64 ReadOnlySection = 65 getContext().getELFSection(".rodata", MCSectionELF::SHT_PROGBITS, 66 MCSectionELF::SHF_ALLOC, 67 SectionKind::getReadOnly()); 68 69 TLSDataSection = 70 getContext().getELFSection(".tdata", MCSectionELF::SHT_PROGBITS, 71 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS | 72 MCSectionELF::SHF_WRITE, 73 SectionKind::getThreadData()); 74 75 TLSBSSSection = 76 getContext().getELFSection(".tbss", MCSectionELF::SHT_NOBITS, 77 MCSectionELF::SHF_ALLOC | MCSectionELF::SHF_TLS | 78 MCSectionELF::SHF_WRITE, 79 SectionKind::getThreadBSS()); 80 81 DataRelSection = 82 getContext().getELFSection(".data.rel", MCSectionELF::SHT_PROGBITS, 83 MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE, 84 SectionKind::getDataRel()); 85 86 DataRelLocalSection = 87 getContext().getELFSection(".data.rel.local", MCSectionELF::SHT_PROGBITS, 88 MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE, 89 SectionKind::getDataRelLocal()); 90 91 DataRelROSection = 92 getContext().getELFSection(".data.rel.ro", MCSectionELF::SHT_PROGBITS, 93 MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE, 94 SectionKind::getReadOnlyWithRel()); 95 96 DataRelROLocalSection = 97 getContext().getELFSection(".data.rel.ro.local", MCSectionELF::SHT_PROGBITS, 98 MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE, 99 SectionKind::getReadOnlyWithRelLocal()); 100 101 MergeableConst4Section = 102 getContext().getELFSection(".rodata.cst4", MCSectionELF::SHT_PROGBITS, 103 MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_MERGE, 104 SectionKind::getMergeableConst4()); 105 106 MergeableConst8Section = 107 getContext().getELFSection(".rodata.cst8", MCSectionELF::SHT_PROGBITS, 108 MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_MERGE, 109 SectionKind::getMergeableConst8()); 110 111 MergeableConst16Section = 112 getContext().getELFSection(".rodata.cst16", MCSectionELF::SHT_PROGBITS, 113 MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_MERGE, 114 SectionKind::getMergeableConst16()); 115 116 StaticCtorSection = 117 getContext().getELFSection(".ctors", MCSectionELF::SHT_PROGBITS, 118 MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE, 119 SectionKind::getDataRel()); 120 121 StaticDtorSection = 122 getContext().getELFSection(".dtors", MCSectionELF::SHT_PROGBITS, 123 MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE, 124 SectionKind::getDataRel()); 125 126 // Exception Handling Sections. 127 128 // FIXME: We're emitting LSDA info into a readonly section on ELF, even though 129 // it contains relocatable pointers. In PIC mode, this is probably a big 130 // runtime hit for C++ apps. Either the contents of the LSDA need to be 131 // adjusted or this should be a data section. 132 LSDASection = 133 getContext().getELFSection(".gcc_except_table", MCSectionELF::SHT_PROGBITS, 134 MCSectionELF::SHF_ALLOC, 135 SectionKind::getReadOnly()); 136 EHFrameSection = 137 getContext().getELFSection(".eh_frame", MCSectionELF::SHT_PROGBITS, 138 MCSectionELF::SHF_ALLOC |MCSectionELF::SHF_WRITE, 139 SectionKind::getDataRel()); 140 141 // Debug Info Sections. 142 DwarfAbbrevSection = 143 getContext().getELFSection(".debug_abbrev", MCSectionELF::SHT_PROGBITS, 0, 144 SectionKind::getMetadata()); 145 DwarfInfoSection = 146 getContext().getELFSection(".debug_info", MCSectionELF::SHT_PROGBITS, 0, 147 SectionKind::getMetadata()); 148 DwarfLineSection = 149 getContext().getELFSection(".debug_line", MCSectionELF::SHT_PROGBITS, 0, 150 SectionKind::getMetadata()); 151 DwarfFrameSection = 152 getContext().getELFSection(".debug_frame", MCSectionELF::SHT_PROGBITS, 0, 153 SectionKind::getMetadata()); 154 DwarfPubNamesSection = 155 getContext().getELFSection(".debug_pubnames", MCSectionELF::SHT_PROGBITS, 0, 156 SectionKind::getMetadata()); 157 DwarfPubTypesSection = 158 getContext().getELFSection(".debug_pubtypes", MCSectionELF::SHT_PROGBITS, 0, 159 SectionKind::getMetadata()); 160 DwarfStrSection = 161 getContext().getELFSection(".debug_str", MCSectionELF::SHT_PROGBITS, 0, 162 SectionKind::getMetadata()); 163 DwarfLocSection = 164 getContext().getELFSection(".debug_loc", MCSectionELF::SHT_PROGBITS, 0, 165 SectionKind::getMetadata()); 166 DwarfARangesSection = 167 getContext().getELFSection(".debug_aranges", MCSectionELF::SHT_PROGBITS, 0, 168 SectionKind::getMetadata()); 169 DwarfRangesSection = 170 getContext().getELFSection(".debug_ranges", MCSectionELF::SHT_PROGBITS, 0, 171 SectionKind::getMetadata()); 172 DwarfMacroInfoSection = 173 getContext().getELFSection(".debug_macinfo", MCSectionELF::SHT_PROGBITS, 0, 174 SectionKind::getMetadata()); 175 } 176 177 178 static SectionKind 179 getELFKindForNamedSection(StringRef Name, SectionKind K) { 180 if (Name.empty() || Name[0] != '.') return K; 181 182 // Some lame default implementation based on some magic section names. 183 if (Name == ".bss" || 184 Name.startswith(".bss.") || 185 Name.startswith(".gnu.linkonce.b.") || 186 Name.startswith(".llvm.linkonce.b.") || 187 Name == ".sbss" || 188 Name.startswith(".sbss.") || 189 Name.startswith(".gnu.linkonce.sb.") || 190 Name.startswith(".llvm.linkonce.sb.")) 191 return SectionKind::getBSS(); 192 193 if (Name == ".tdata" || 194 Name.startswith(".tdata.") || 195 Name.startswith(".gnu.linkonce.td.") || 196 Name.startswith(".llvm.linkonce.td.")) 197 return SectionKind::getThreadData(); 198 199 if (Name == ".tbss" || 200 Name.startswith(".tbss.") || 201 Name.startswith(".gnu.linkonce.tb.") || 202 Name.startswith(".llvm.linkonce.tb.")) 203 return SectionKind::getThreadBSS(); 204 205 return K; 206 } 207 208 209 static unsigned getELFSectionType(StringRef Name, SectionKind K) { 210 211 if (Name == ".init_array") 212 return MCSectionELF::SHT_INIT_ARRAY; 213 214 if (Name == ".fini_array") 215 return MCSectionELF::SHT_FINI_ARRAY; 216 217 if (Name == ".preinit_array") 218 return MCSectionELF::SHT_PREINIT_ARRAY; 219 220 if (K.isBSS() || K.isThreadBSS()) 221 return MCSectionELF::SHT_NOBITS; 222 223 return MCSectionELF::SHT_PROGBITS; 224 } 225 226 227 static unsigned 228 getELFSectionFlags(SectionKind K) { 229 unsigned Flags = 0; 230 231 if (!K.isMetadata()) 232 Flags |= MCSectionELF::SHF_ALLOC; 233 234 if (K.isText()) 235 Flags |= MCSectionELF::SHF_EXECINSTR; 236 237 if (K.isWriteable()) 238 Flags |= MCSectionELF::SHF_WRITE; 239 240 if (K.isThreadLocal()) 241 Flags |= MCSectionELF::SHF_TLS; 242 243 // K.isMergeableConst() is left out to honour PR4650 244 if (K.isMergeableCString() || K.isMergeableConst4() || 245 K.isMergeableConst8() || K.isMergeableConst16()) 246 Flags |= MCSectionELF::SHF_MERGE; 247 248 if (K.isMergeableCString()) 249 Flags |= MCSectionELF::SHF_STRINGS; 250 251 return Flags; 252 } 253 254 255 const MCSection *TargetLoweringObjectFileELF:: 256 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 257 Mangler *Mang, const TargetMachine &TM) const { 258 StringRef SectionName = GV->getSection(); 259 260 // Infer section flags from the section name if we can. 261 Kind = getELFKindForNamedSection(SectionName, Kind); 262 263 return getContext().getELFSection(SectionName, 264 getELFSectionType(SectionName, Kind), 265 getELFSectionFlags(Kind), Kind, true); 266 } 267 268 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) { 269 if (Kind.isText()) return ".gnu.linkonce.t."; 270 if (Kind.isReadOnly()) return ".gnu.linkonce.r."; 271 272 if (Kind.isThreadData()) return ".gnu.linkonce.td."; 273 if (Kind.isThreadBSS()) return ".gnu.linkonce.tb."; 274 275 if (Kind.isDataNoRel()) return ".gnu.linkonce.d."; 276 if (Kind.isDataRelLocal()) return ".gnu.linkonce.d.rel.local."; 277 if (Kind.isDataRel()) return ".gnu.linkonce.d.rel."; 278 if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local."; 279 280 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 281 return ".gnu.linkonce.d.rel.ro."; 282 } 283 284 /// getSectionPrefixForGlobal - Return the section prefix name used by options 285 /// FunctionsSections and DataSections. 286 static const char *getSectionPrefixForGlobal(SectionKind Kind) { 287 if (Kind.isText()) return ".text."; 288 if (Kind.isReadOnly()) return ".rodata."; 289 290 if (Kind.isThreadData()) return ".tdata."; 291 if (Kind.isThreadBSS()) return ".tbss."; 292 293 if (Kind.isDataNoRel()) return ".data."; 294 if (Kind.isDataRelLocal()) return ".data.rel.local."; 295 if (Kind.isDataRel()) return ".data.rel."; 296 if (Kind.isReadOnlyWithRelLocal()) return ".data.rel.ro.local."; 297 298 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 299 return ".data.rel.ro."; 300 } 301 302 303 const MCSection *TargetLoweringObjectFileELF:: 304 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 305 Mangler *Mang, const TargetMachine &TM) const { 306 // If we have -ffunction-section or -fdata-section then we should emit the 307 // global value to a uniqued section specifically for it. 308 bool EmitUniquedSection; 309 if (Kind.isText()) 310 EmitUniquedSection = TM.getFunctionSections(); 311 else 312 EmitUniquedSection = TM.getDataSections(); 313 314 // If this global is linkonce/weak and the target handles this by emitting it 315 // into a 'uniqued' section name, create and return the section now. 316 if ((GV->isWeakForLinker() || EmitUniquedSection) && 317 !Kind.isCommon() && !Kind.isBSS()) { 318 const char *Prefix; 319 if (GV->isWeakForLinker()) 320 Prefix = getSectionPrefixForUniqueGlobal(Kind); 321 else { 322 assert(EmitUniquedSection); 323 Prefix = getSectionPrefixForGlobal(Kind); 324 } 325 326 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 327 MCSymbol *Sym = Mang->getSymbol(GV); 328 Name.append(Sym->getName().begin(), Sym->getName().end()); 329 return getContext().getELFSection(Name.str(), 330 getELFSectionType(Name.str(), Kind), 331 getELFSectionFlags(Kind), Kind); 332 } 333 334 if (Kind.isText()) return TextSection; 335 336 if (Kind.isMergeable1ByteCString() || 337 Kind.isMergeable2ByteCString() || 338 Kind.isMergeable4ByteCString()) { 339 340 // We also need alignment here. 341 // FIXME: this is getting the alignment of the character, not the 342 // alignment of the global! 343 unsigned Align = 344 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)); 345 346 const char *SizeSpec = ".rodata.str1."; 347 if (Kind.isMergeable2ByteCString()) 348 SizeSpec = ".rodata.str2."; 349 else if (Kind.isMergeable4ByteCString()) 350 SizeSpec = ".rodata.str4."; 351 else 352 assert(Kind.isMergeable1ByteCString() && "unknown string width"); 353 354 355 std::string Name = SizeSpec + utostr(Align); 356 return getContext().getELFSection(Name, MCSectionELF::SHT_PROGBITS, 357 MCSectionELF::SHF_ALLOC | 358 MCSectionELF::SHF_MERGE | 359 MCSectionELF::SHF_STRINGS, 360 Kind); 361 } 362 363 if (Kind.isMergeableConst()) { 364 if (Kind.isMergeableConst4() && MergeableConst4Section) 365 return MergeableConst4Section; 366 if (Kind.isMergeableConst8() && MergeableConst8Section) 367 return MergeableConst8Section; 368 if (Kind.isMergeableConst16() && MergeableConst16Section) 369 return MergeableConst16Section; 370 return ReadOnlySection; // .const 371 } 372 373 if (Kind.isReadOnly()) return ReadOnlySection; 374 375 if (Kind.isThreadData()) return TLSDataSection; 376 if (Kind.isThreadBSS()) return TLSBSSSection; 377 378 // Note: we claim that common symbols are put in BSSSection, but they are 379 // really emitted with the magic .comm directive, which creates a symbol table 380 // entry but not a section. 381 if (Kind.isBSS() || Kind.isCommon()) return BSSSection; 382 383 if (Kind.isDataNoRel()) return DataSection; 384 if (Kind.isDataRelLocal()) return DataRelLocalSection; 385 if (Kind.isDataRel()) return DataRelSection; 386 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 387 388 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 389 return DataRelROSection; 390 } 391 392 /// getSectionForConstant - Given a mergeable constant with the 393 /// specified size and relocation information, return a section that it 394 /// should be placed in. 395 const MCSection *TargetLoweringObjectFileELF:: 396 getSectionForConstant(SectionKind Kind) const { 397 if (Kind.isMergeableConst4() && MergeableConst4Section) 398 return MergeableConst4Section; 399 if (Kind.isMergeableConst8() && MergeableConst8Section) 400 return MergeableConst8Section; 401 if (Kind.isMergeableConst16() && MergeableConst16Section) 402 return MergeableConst16Section; 403 if (Kind.isReadOnly()) 404 return ReadOnlySection; 405 406 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 407 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 408 return DataRelROSection; 409 } 410 411 const MCExpr *TargetLoweringObjectFileELF:: 412 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 413 MachineModuleInfo *MMI, 414 unsigned Encoding, MCStreamer &Streamer) const { 415 416 if (Encoding & dwarf::DW_EH_PE_indirect) { 417 MachineModuleInfoELF &ELFMMI = MMI->getObjFileInfo<MachineModuleInfoELF>(); 418 419 SmallString<128> Name; 420 Mang->getNameWithPrefix(Name, GV, true); 421 Name += ".DW.stub"; 422 423 // Add information about the stub reference to ELFMMI so that the stub 424 // gets emitted by the asmprinter. 425 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); 426 MachineModuleInfoImpl::StubValueTy &StubSym = ELFMMI.getGVStubEntry(SSym); 427 if (StubSym.getPointer() == 0) { 428 MCSymbol *Sym = Mang->getSymbol(GV); 429 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 430 } 431 432 return TargetLoweringObjectFile:: 433 getExprForDwarfReference(SSym, Mang, MMI, 434 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 435 } 436 437 return TargetLoweringObjectFile:: 438 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); 439 } 440 441 //===----------------------------------------------------------------------===// 442 // MachO 443 //===----------------------------------------------------------------------===// 444 445 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx, 446 const TargetMachine &TM) { 447 IsFunctionEHSymbolGlobal = true; 448 IsFunctionEHFrameSymbolPrivate = false; 449 SupportsWeakOmittedEHFrame = false; 450 451 Triple T(((LLVMTargetMachine&)TM).getTargetTriple()); 452 if (T.getOS() == Triple::Darwin) { 453 unsigned MajNum = T.getDarwinMajorNumber(); 454 if (MajNum == 7 || MajNum == 8) // 10.3 Panther, 10.4 Tiger 455 CommDirectiveSupportsAlignment = false; 456 if (MajNum > 9) // 10.6 SnowLeopard 457 IsFunctionEHSymbolGlobal = false; 458 } 459 460 TargetLoweringObjectFile::Initialize(Ctx, TM); 461 462 TextSection // .text 463 = getContext().getMachOSection("__TEXT", "__text", 464 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 465 SectionKind::getText()); 466 DataSection // .data 467 = getContext().getMachOSection("__DATA", "__data", 0, 468 SectionKind::getDataRel()); 469 470 TLSDataSection // .tdata 471 = getContext().getMachOSection("__DATA", "__thread_data", 472 MCSectionMachO::S_THREAD_LOCAL_REGULAR, 473 SectionKind::getDataRel()); 474 TLSBSSSection // .tbss 475 = getContext().getMachOSection("__DATA", "__thread_bss", 476 MCSectionMachO::S_THREAD_LOCAL_ZEROFILL, 477 SectionKind::getThreadBSS()); 478 479 // TODO: Verify datarel below. 480 TLSTLVSection // .tlv 481 = getContext().getMachOSection("__DATA", "__thread_vars", 482 MCSectionMachO::S_THREAD_LOCAL_VARIABLES, 483 SectionKind::getDataRel()); 484 485 TLSThreadInitSection 486 = getContext().getMachOSection("__DATA", "__thread_init", 487 MCSectionMachO::S_THREAD_LOCAL_INIT_FUNCTION_POINTERS, 488 SectionKind::getDataRel()); 489 490 CStringSection // .cstring 491 = getContext().getMachOSection("__TEXT", "__cstring", 492 MCSectionMachO::S_CSTRING_LITERALS, 493 SectionKind::getMergeable1ByteCString()); 494 UStringSection 495 = getContext().getMachOSection("__TEXT","__ustring", 0, 496 SectionKind::getMergeable2ByteCString()); 497 FourByteConstantSection // .literal4 498 = getContext().getMachOSection("__TEXT", "__literal4", 499 MCSectionMachO::S_4BYTE_LITERALS, 500 SectionKind::getMergeableConst4()); 501 EightByteConstantSection // .literal8 502 = getContext().getMachOSection("__TEXT", "__literal8", 503 MCSectionMachO::S_8BYTE_LITERALS, 504 SectionKind::getMergeableConst8()); 505 506 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back 507 // to using it in -static mode. 508 SixteenByteConstantSection = 0; 509 if (TM.getRelocationModel() != Reloc::Static && 510 TM.getTargetData()->getPointerSize() == 32) 511 SixteenByteConstantSection = // .literal16 512 getContext().getMachOSection("__TEXT", "__literal16", 513 MCSectionMachO::S_16BYTE_LITERALS, 514 SectionKind::getMergeableConst16()); 515 516 ReadOnlySection // .const 517 = getContext().getMachOSection("__TEXT", "__const", 0, 518 SectionKind::getReadOnly()); 519 520 TextCoalSection 521 = getContext().getMachOSection("__TEXT", "__textcoal_nt", 522 MCSectionMachO::S_COALESCED | 523 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 524 SectionKind::getText()); 525 ConstTextCoalSection 526 = getContext().getMachOSection("__TEXT", "__const_coal", 527 MCSectionMachO::S_COALESCED, 528 SectionKind::getReadOnly()); 529 ConstDataSection // .const_data 530 = getContext().getMachOSection("__DATA", "__const", 0, 531 SectionKind::getReadOnlyWithRel()); 532 DataCoalSection 533 = getContext().getMachOSection("__DATA","__datacoal_nt", 534 MCSectionMachO::S_COALESCED, 535 SectionKind::getDataRel()); 536 DataCommonSection 537 = getContext().getMachOSection("__DATA","__common", 538 MCSectionMachO::S_ZEROFILL, 539 SectionKind::getBSS()); 540 DataBSSSection 541 = getContext().getMachOSection("__DATA","__bss", MCSectionMachO::S_ZEROFILL, 542 SectionKind::getBSS()); 543 544 545 LazySymbolPointerSection 546 = getContext().getMachOSection("__DATA", "__la_symbol_ptr", 547 MCSectionMachO::S_LAZY_SYMBOL_POINTERS, 548 SectionKind::getMetadata()); 549 NonLazySymbolPointerSection 550 = getContext().getMachOSection("__DATA", "__nl_symbol_ptr", 551 MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS, 552 SectionKind::getMetadata()); 553 554 if (TM.getRelocationModel() == Reloc::Static) { 555 StaticCtorSection 556 = getContext().getMachOSection("__TEXT", "__constructor", 0, 557 SectionKind::getDataRel()); 558 StaticDtorSection 559 = getContext().getMachOSection("__TEXT", "__destructor", 0, 560 SectionKind::getDataRel()); 561 } else { 562 StaticCtorSection 563 = getContext().getMachOSection("__DATA", "__mod_init_func", 564 MCSectionMachO::S_MOD_INIT_FUNC_POINTERS, 565 SectionKind::getDataRel()); 566 StaticDtorSection 567 = getContext().getMachOSection("__DATA", "__mod_term_func", 568 MCSectionMachO::S_MOD_TERM_FUNC_POINTERS, 569 SectionKind::getDataRel()); 570 } 571 572 // Exception Handling. 573 LSDASection = getContext().getMachOSection("__TEXT", "__gcc_except_tab", 0, 574 SectionKind::getReadOnlyWithRel()); 575 EHFrameSection = 576 getContext().getMachOSection("__TEXT", "__eh_frame", 577 MCSectionMachO::S_COALESCED | 578 MCSectionMachO::S_ATTR_NO_TOC | 579 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS | 580 MCSectionMachO::S_ATTR_LIVE_SUPPORT, 581 SectionKind::getReadOnly()); 582 583 // Debug Information. 584 DwarfAbbrevSection = 585 getContext().getMachOSection("__DWARF", "__debug_abbrev", 586 MCSectionMachO::S_ATTR_DEBUG, 587 SectionKind::getMetadata()); 588 DwarfInfoSection = 589 getContext().getMachOSection("__DWARF", "__debug_info", 590 MCSectionMachO::S_ATTR_DEBUG, 591 SectionKind::getMetadata()); 592 DwarfLineSection = 593 getContext().getMachOSection("__DWARF", "__debug_line", 594 MCSectionMachO::S_ATTR_DEBUG, 595 SectionKind::getMetadata()); 596 DwarfFrameSection = 597 getContext().getMachOSection("__DWARF", "__debug_frame", 598 MCSectionMachO::S_ATTR_DEBUG, 599 SectionKind::getMetadata()); 600 DwarfPubNamesSection = 601 getContext().getMachOSection("__DWARF", "__debug_pubnames", 602 MCSectionMachO::S_ATTR_DEBUG, 603 SectionKind::getMetadata()); 604 DwarfPubTypesSection = 605 getContext().getMachOSection("__DWARF", "__debug_pubtypes", 606 MCSectionMachO::S_ATTR_DEBUG, 607 SectionKind::getMetadata()); 608 DwarfStrSection = 609 getContext().getMachOSection("__DWARF", "__debug_str", 610 MCSectionMachO::S_ATTR_DEBUG, 611 SectionKind::getMetadata()); 612 DwarfLocSection = 613 getContext().getMachOSection("__DWARF", "__debug_loc", 614 MCSectionMachO::S_ATTR_DEBUG, 615 SectionKind::getMetadata()); 616 DwarfARangesSection = 617 getContext().getMachOSection("__DWARF", "__debug_aranges", 618 MCSectionMachO::S_ATTR_DEBUG, 619 SectionKind::getMetadata()); 620 DwarfRangesSection = 621 getContext().getMachOSection("__DWARF", "__debug_ranges", 622 MCSectionMachO::S_ATTR_DEBUG, 623 SectionKind::getMetadata()); 624 DwarfMacroInfoSection = 625 getContext().getMachOSection("__DWARF", "__debug_macinfo", 626 MCSectionMachO::S_ATTR_DEBUG, 627 SectionKind::getMetadata()); 628 DwarfDebugInlineSection = 629 getContext().getMachOSection("__DWARF", "__debug_inlined", 630 MCSectionMachO::S_ATTR_DEBUG, 631 SectionKind::getMetadata()); 632 633 TLSExtraDataSection = TLSTLVSection; 634 } 635 636 const MCSection *TargetLoweringObjectFileMachO:: 637 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 638 Mangler *Mang, const TargetMachine &TM) const { 639 // Parse the section specifier and create it if valid. 640 StringRef Segment, Section; 641 unsigned TAA, StubSize; 642 std::string ErrorCode = 643 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, 644 TAA, StubSize); 645 if (!ErrorCode.empty()) { 646 // If invalid, report the error with report_fatal_error. 647 report_fatal_error("Global variable '" + GV->getNameStr() + 648 "' has an invalid section specifier '" + GV->getSection()+ 649 "': " + ErrorCode + "."); 650 // Fall back to dropping it into the data section. 651 return DataSection; 652 } 653 654 // Get the section. 655 const MCSectionMachO *S = 656 getContext().getMachOSection(Segment, Section, TAA, StubSize, Kind); 657 658 // Okay, now that we got the section, verify that the TAA & StubSize agree. 659 // If the user declared multiple globals with different section flags, we need 660 // to reject it here. 661 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) { 662 // If invalid, report the error with report_fatal_error. 663 report_fatal_error("Global variable '" + GV->getNameStr() + 664 "' section type or attributes does not match previous" 665 " section specifier"); 666 } 667 668 return S; 669 } 670 671 const MCSection *TargetLoweringObjectFileMachO:: 672 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 673 Mangler *Mang, const TargetMachine &TM) const { 674 675 // Handle thread local data. 676 if (Kind.isThreadBSS()) return TLSBSSSection; 677 if (Kind.isThreadData()) return TLSDataSection; 678 679 if (Kind.isText()) 680 return GV->isWeakForLinker() ? TextCoalSection : TextSection; 681 682 // If this is weak/linkonce, put this in a coalescable section, either in text 683 // or data depending on if it is writable. 684 if (GV->isWeakForLinker()) { 685 if (Kind.isReadOnly()) 686 return ConstTextCoalSection; 687 return DataCoalSection; 688 } 689 690 // FIXME: Alignment check should be handled by section classifier. 691 if (Kind.isMergeable1ByteCString() && 692 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 693 return CStringSection; 694 695 // Do not put 16-bit arrays in the UString section if they have an 696 // externally visible label, this runs into issues with certain linker 697 // versions. 698 if (Kind.isMergeable2ByteCString() && !GV->hasExternalLinkage() && 699 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)) < 32) 700 return UStringSection; 701 702 if (Kind.isMergeableConst()) { 703 if (Kind.isMergeableConst4()) 704 return FourByteConstantSection; 705 if (Kind.isMergeableConst8()) 706 return EightByteConstantSection; 707 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 708 return SixteenByteConstantSection; 709 } 710 711 // Otherwise, if it is readonly, but not something we can specially optimize, 712 // just drop it in .const. 713 if (Kind.isReadOnly()) 714 return ReadOnlySection; 715 716 // If this is marked const, put it into a const section. But if the dynamic 717 // linker needs to write to it, put it in the data segment. 718 if (Kind.isReadOnlyWithRel()) 719 return ConstDataSection; 720 721 // Put zero initialized globals with strong external linkage in the 722 // DATA, __common section with the .zerofill directive. 723 if (Kind.isBSSExtern()) 724 return DataCommonSection; 725 726 // Put zero initialized globals with local linkage in __DATA,__bss directive 727 // with the .zerofill directive (aka .lcomm). 728 if (Kind.isBSSLocal()) 729 return DataBSSSection; 730 731 // Otherwise, just drop the variable in the normal data section. 732 return DataSection; 733 } 734 735 const MCSection * 736 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { 737 // If this constant requires a relocation, we have to put it in the data 738 // segment, not in the text segment. 739 if (Kind.isDataRel() || Kind.isReadOnlyWithRel()) 740 return ConstDataSection; 741 742 if (Kind.isMergeableConst4()) 743 return FourByteConstantSection; 744 if (Kind.isMergeableConst8()) 745 return EightByteConstantSection; 746 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 747 return SixteenByteConstantSection; 748 return ReadOnlySection; // .const 749 } 750 751 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide 752 /// not to emit the UsedDirective for some symbols in llvm.used. 753 // FIXME: REMOVE this (rdar://7071300) 754 bool TargetLoweringObjectFileMachO:: 755 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { 756 /// On Darwin, internally linked data beginning with "L" or "l" does not have 757 /// the directive emitted (this occurs in ObjC metadata). 758 if (!GV) return false; 759 760 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. 761 if (GV->hasLocalLinkage() && !isa<Function>(GV)) { 762 // FIXME: ObjC metadata is currently emitted as internal symbols that have 763 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and 764 // this horrible hack can go away. 765 MCSymbol *Sym = Mang->getSymbol(GV); 766 if (Sym->getName()[0] == 'L' || Sym->getName()[0] == 'l') 767 return false; 768 } 769 770 return true; 771 } 772 773 const MCExpr *TargetLoweringObjectFileMachO:: 774 getExprForDwarfGlobalReference(const GlobalValue *GV, Mangler *Mang, 775 MachineModuleInfo *MMI, unsigned Encoding, 776 MCStreamer &Streamer) const { 777 // The mach-o version of this method defaults to returning a stub reference. 778 779 if (Encoding & DW_EH_PE_indirect) { 780 MachineModuleInfoMachO &MachOMMI = 781 MMI->getObjFileInfo<MachineModuleInfoMachO>(); 782 783 SmallString<128> Name; 784 Mang->getNameWithPrefix(Name, GV, true); 785 Name += "$non_lazy_ptr"; 786 787 // Add information about the stub reference to MachOMMI so that the stub 788 // gets emitted by the asmprinter. 789 MCSymbol *SSym = getContext().GetOrCreateSymbol(Name.str()); 790 MachineModuleInfoImpl::StubValueTy &StubSym = MachOMMI.getGVStubEntry(SSym); 791 if (StubSym.getPointer() == 0) { 792 MCSymbol *Sym = Mang->getSymbol(GV); 793 StubSym = MachineModuleInfoImpl::StubValueTy(Sym, !GV->hasLocalLinkage()); 794 } 795 796 return TargetLoweringObjectFile:: 797 getExprForDwarfReference(SSym, Mang, MMI, 798 Encoding & ~dwarf::DW_EH_PE_indirect, Streamer); 799 } 800 801 return TargetLoweringObjectFile:: 802 getExprForDwarfGlobalReference(GV, Mang, MMI, Encoding, Streamer); 803 } 804 805 unsigned TargetLoweringObjectFileMachO::getPersonalityEncoding() const { 806 return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4; 807 } 808 809 unsigned TargetLoweringObjectFileMachO::getLSDAEncoding() const { 810 return DW_EH_PE_pcrel; 811 } 812 813 unsigned TargetLoweringObjectFileMachO::getFDEEncoding() const { 814 return DW_EH_PE_pcrel; 815 } 816 817 unsigned TargetLoweringObjectFileMachO::getTTypeEncoding() const { 818 return DW_EH_PE_indirect | DW_EH_PE_pcrel | DW_EH_PE_sdata4; 819 } 820 821 //===----------------------------------------------------------------------===// 822 // COFF 823 //===----------------------------------------------------------------------===// 824 825 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx, 826 const TargetMachine &TM) { 827 TargetLoweringObjectFile::Initialize(Ctx, TM); 828 TextSection = 829 getContext().getCOFFSection(".text", 830 COFF::IMAGE_SCN_CNT_CODE | 831 COFF::IMAGE_SCN_MEM_EXECUTE | 832 COFF::IMAGE_SCN_MEM_READ, 833 SectionKind::getText()); 834 DataSection = 835 getContext().getCOFFSection(".data", 836 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 837 COFF::IMAGE_SCN_MEM_READ | 838 COFF::IMAGE_SCN_MEM_WRITE, 839 SectionKind::getDataRel()); 840 ReadOnlySection = 841 getContext().getCOFFSection(".rdata", 842 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 843 COFF::IMAGE_SCN_MEM_READ, 844 SectionKind::getReadOnly()); 845 StaticCtorSection = 846 getContext().getCOFFSection(".ctors", 847 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 848 COFF::IMAGE_SCN_MEM_READ | 849 COFF::IMAGE_SCN_MEM_WRITE, 850 SectionKind::getDataRel()); 851 StaticDtorSection = 852 getContext().getCOFFSection(".dtors", 853 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 854 COFF::IMAGE_SCN_MEM_READ | 855 COFF::IMAGE_SCN_MEM_WRITE, 856 SectionKind::getDataRel()); 857 858 // FIXME: We're emitting LSDA info into a readonly section on COFF, even 859 // though it contains relocatable pointers. In PIC mode, this is probably a 860 // big runtime hit for C++ apps. Either the contents of the LSDA need to be 861 // adjusted or this should be a data section. 862 LSDASection = 863 getContext().getCOFFSection(".gcc_except_table", 864 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 865 COFF::IMAGE_SCN_MEM_READ, 866 SectionKind::getReadOnly()); 867 EHFrameSection = 868 getContext().getCOFFSection(".eh_frame", 869 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 870 COFF::IMAGE_SCN_MEM_READ | 871 COFF::IMAGE_SCN_MEM_WRITE, 872 SectionKind::getDataRel()); 873 874 // Debug info. 875 DwarfAbbrevSection = 876 getContext().getCOFFSection(".debug_abbrev", 877 COFF::IMAGE_SCN_MEM_DISCARDABLE | 878 COFF::IMAGE_SCN_MEM_READ, 879 SectionKind::getMetadata()); 880 DwarfInfoSection = 881 getContext().getCOFFSection(".debug_info", 882 COFF::IMAGE_SCN_MEM_DISCARDABLE | 883 COFF::IMAGE_SCN_MEM_READ, 884 SectionKind::getMetadata()); 885 DwarfLineSection = 886 getContext().getCOFFSection(".debug_line", 887 COFF::IMAGE_SCN_MEM_DISCARDABLE | 888 COFF::IMAGE_SCN_MEM_READ, 889 SectionKind::getMetadata()); 890 DwarfFrameSection = 891 getContext().getCOFFSection(".debug_frame", 892 COFF::IMAGE_SCN_MEM_DISCARDABLE | 893 COFF::IMAGE_SCN_MEM_READ, 894 SectionKind::getMetadata()); 895 DwarfPubNamesSection = 896 getContext().getCOFFSection(".debug_pubnames", 897 COFF::IMAGE_SCN_MEM_DISCARDABLE | 898 COFF::IMAGE_SCN_MEM_READ, 899 SectionKind::getMetadata()); 900 DwarfPubTypesSection = 901 getContext().getCOFFSection(".debug_pubtypes", 902 COFF::IMAGE_SCN_MEM_DISCARDABLE | 903 COFF::IMAGE_SCN_MEM_READ, 904 SectionKind::getMetadata()); 905 DwarfStrSection = 906 getContext().getCOFFSection(".debug_str", 907 COFF::IMAGE_SCN_MEM_DISCARDABLE | 908 COFF::IMAGE_SCN_MEM_READ, 909 SectionKind::getMetadata()); 910 DwarfLocSection = 911 getContext().getCOFFSection(".debug_loc", 912 COFF::IMAGE_SCN_MEM_DISCARDABLE | 913 COFF::IMAGE_SCN_MEM_READ, 914 SectionKind::getMetadata()); 915 DwarfARangesSection = 916 getContext().getCOFFSection(".debug_aranges", 917 COFF::IMAGE_SCN_MEM_DISCARDABLE | 918 COFF::IMAGE_SCN_MEM_READ, 919 SectionKind::getMetadata()); 920 DwarfRangesSection = 921 getContext().getCOFFSection(".debug_ranges", 922 COFF::IMAGE_SCN_MEM_DISCARDABLE | 923 COFF::IMAGE_SCN_MEM_READ, 924 SectionKind::getMetadata()); 925 DwarfMacroInfoSection = 926 getContext().getCOFFSection(".debug_macinfo", 927 COFF::IMAGE_SCN_MEM_DISCARDABLE | 928 COFF::IMAGE_SCN_MEM_READ, 929 SectionKind::getMetadata()); 930 931 DrectveSection = 932 getContext().getCOFFSection(".drectve", 933 COFF::IMAGE_SCN_LNK_INFO, 934 SectionKind::getMetadata()); 935 } 936 937 static unsigned 938 getCOFFSectionFlags(SectionKind K) { 939 unsigned Flags = 0; 940 941 if (K.isMetadata()) 942 Flags |= 943 COFF::IMAGE_SCN_MEM_DISCARDABLE; 944 else if (K.isText()) 945 Flags |= 946 COFF::IMAGE_SCN_MEM_EXECUTE | 947 COFF::IMAGE_SCN_CNT_CODE; 948 else if (K.isBSS ()) 949 Flags |= 950 COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA | 951 COFF::IMAGE_SCN_MEM_READ | 952 COFF::IMAGE_SCN_MEM_WRITE; 953 else if (K.isReadOnly()) 954 Flags |= 955 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 956 COFF::IMAGE_SCN_MEM_READ; 957 else if (K.isWriteable()) 958 Flags |= 959 COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | 960 COFF::IMAGE_SCN_MEM_READ | 961 COFF::IMAGE_SCN_MEM_WRITE; 962 963 return Flags; 964 } 965 966 const MCSection *TargetLoweringObjectFileCOFF:: 967 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 968 Mangler *Mang, const TargetMachine &TM) const { 969 return getContext().getCOFFSection(GV->getSection(), 970 getCOFFSectionFlags(Kind), 971 Kind); 972 } 973 974 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { 975 if (Kind.isText()) 976 return ".text$linkonce"; 977 if (Kind.isBSS ()) 978 return ".bss$linkonce"; 979 if (Kind.isWriteable()) 980 return ".data$linkonce"; 981 return ".rdata$linkonce"; 982 } 983 984 985 const MCSection *TargetLoweringObjectFileCOFF:: 986 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 987 Mangler *Mang, const TargetMachine &TM) const { 988 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 989 990 // If this global is linkonce/weak and the target handles this by emitting it 991 // into a 'uniqued' section name, create and return the section now. 992 if (GV->isWeakForLinker()) { 993 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); 994 SmallString<128> Name(Prefix, Prefix+strlen(Prefix)); 995 MCSymbol *Sym = Mang->getSymbol(GV); 996 Name.append(Sym->getName().begin(), Sym->getName().end()); 997 998 unsigned Characteristics = getCOFFSectionFlags(Kind); 999 1000 Characteristics |= COFF::IMAGE_SCN_LNK_COMDAT; 1001 1002 return getContext().getCOFFSection(Name.str(), Characteristics, 1003 COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH, Kind); 1004 } 1005 1006 if (Kind.isText()) 1007 return getTextSection(); 1008 1009 return getDataSection(); 1010 } 1011 1012