1 //===-- llvm/Target/TargetLoweringObjectFile.cpp - Object File Info -------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements classes used to handle lowerings specific to common 11 // object file formats. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "llvm/Target/TargetLoweringObjectFile.h" 16 #include "llvm/Constants.h" 17 #include "llvm/DerivedTypes.h" 18 #include "llvm/Function.h" 19 #include "llvm/GlobalVariable.h" 20 #include "llvm/MC/MCContext.h" 21 #include "llvm/MC/MCSectionMachO.h" 22 #include "llvm/Target/TargetAsmInfo.h" 23 #include "llvm/Target/TargetData.h" 24 #include "llvm/Target/TargetMachine.h" 25 #include "llvm/Target/TargetOptions.h" 26 #include "llvm/Support/Mangler.h" 27 #include "llvm/ADT/SmallString.h" 28 #include "llvm/ADT/StringExtras.h" 29 using namespace llvm; 30 31 //===----------------------------------------------------------------------===// 32 // Generic Code 33 //===----------------------------------------------------------------------===// 34 35 TargetLoweringObjectFile::TargetLoweringObjectFile() : Ctx(0) { 36 TextSection = 0; 37 DataSection = 0; 38 BSSSection = 0; 39 ReadOnlySection = 0; 40 StaticCtorSection = 0; 41 StaticDtorSection = 0; 42 LSDASection = 0; 43 EHFrameSection = 0; 44 45 DwarfAbbrevSection = 0; 46 DwarfInfoSection = 0; 47 DwarfLineSection = 0; 48 DwarfFrameSection = 0; 49 DwarfPubNamesSection = 0; 50 DwarfPubTypesSection = 0; 51 DwarfDebugInlineSection = 0; 52 DwarfStrSection = 0; 53 DwarfLocSection = 0; 54 DwarfARangesSection = 0; 55 DwarfRangesSection = 0; 56 DwarfMacroInfoSection = 0; 57 } 58 59 TargetLoweringObjectFile::~TargetLoweringObjectFile() { 60 } 61 62 static bool isSuitableForBSS(const GlobalVariable *GV) { 63 Constant *C = GV->getInitializer(); 64 65 // Must have zero initializer. 66 if (!C->isNullValue()) 67 return false; 68 69 // Leave constant zeros in readonly constant sections, so they can be shared. 70 if (GV->isConstant()) 71 return false; 72 73 // If the global has an explicit section specified, don't put it in BSS. 74 if (!GV->getSection().empty()) 75 return false; 76 77 // If -nozero-initialized-in-bss is specified, don't ever use BSS. 78 if (NoZerosInBSS) 79 return false; 80 81 // Otherwise, put it in BSS! 82 return true; 83 } 84 85 /// IsNullTerminatedString - Return true if the specified constant (which is 86 /// known to have a type that is an array of 1/2/4 byte elements) ends with a 87 /// nul value and contains no other nuls in it. 88 static bool IsNullTerminatedString(const Constant *C) { 89 const ArrayType *ATy = cast<ArrayType>(C->getType()); 90 91 // First check: is we have constant array of i8 terminated with zero 92 if (const ConstantArray *CVA = dyn_cast<ConstantArray>(C)) { 93 if (ATy->getNumElements() == 0) return false; 94 95 ConstantInt *Null = 96 dyn_cast<ConstantInt>(CVA->getOperand(ATy->getNumElements()-1)); 97 if (Null == 0 || Null->getZExtValue() != 0) 98 return false; // Not null terminated. 99 100 // Verify that the null doesn't occur anywhere else in the string. 101 for (unsigned i = 0, e = ATy->getNumElements()-1; i != e; ++i) 102 // Reject constantexpr elements etc. 103 if (!isa<ConstantInt>(CVA->getOperand(i)) || 104 CVA->getOperand(i) == Null) 105 return false; 106 return true; 107 } 108 109 // Another possibility: [1 x i8] zeroinitializer 110 if (isa<ConstantAggregateZero>(C)) 111 return ATy->getNumElements() == 1; 112 113 return false; 114 } 115 116 /// getKindForGlobal - This is a top-level target-independent classifier for 117 /// a global variable. Given an global variable and information from TM, it 118 /// classifies the global in a variety of ways that make various target 119 /// implementations simpler. The target implementation is free to ignore this 120 /// extra info of course. 121 SectionKind TargetLoweringObjectFile::getKindForGlobal(const GlobalValue *GV, 122 const TargetMachine &TM){ 123 assert(!GV->isDeclaration() && !GV->hasAvailableExternallyLinkage() && 124 "Can only be used for global definitions"); 125 126 Reloc::Model ReloModel = TM.getRelocationModel(); 127 128 // Early exit - functions should be always in text sections. 129 const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV); 130 if (GVar == 0) 131 return SectionKind::getText(); 132 133 // Handle thread-local data first. 134 if (GVar->isThreadLocal()) { 135 if (isSuitableForBSS(GVar)) 136 return SectionKind::getThreadBSS(); 137 return SectionKind::getThreadData(); 138 } 139 140 // Variable can be easily put to BSS section. 141 if (isSuitableForBSS(GVar)) 142 return SectionKind::getBSS(); 143 144 Constant *C = GVar->getInitializer(); 145 146 // If the global is marked constant, we can put it into a mergable section, 147 // a mergable string section, or general .data if it contains relocations. 148 if (GVar->isConstant()) { 149 // If the initializer for the global contains something that requires a 150 // relocation, then we may have to drop this into a wriable data section 151 // even though it is marked const. 152 switch (C->getRelocationInfo()) { 153 default: llvm_unreachable("unknown relocation info kind"); 154 case Constant::NoRelocation: 155 // If initializer is a null-terminated string, put it in a "cstring" 156 // section of the right width. 157 if (const ArrayType *ATy = dyn_cast<ArrayType>(C->getType())) { 158 if (const IntegerType *ITy = 159 dyn_cast<IntegerType>(ATy->getElementType())) { 160 if ((ITy->getBitWidth() == 8 || ITy->getBitWidth() == 16 || 161 ITy->getBitWidth() == 32) && 162 IsNullTerminatedString(C)) { 163 if (ITy->getBitWidth() == 8) 164 return SectionKind::getMergeable1ByteCString(); 165 if (ITy->getBitWidth() == 16) 166 return SectionKind::getMergeable2ByteCString(); 167 168 assert(ITy->getBitWidth() == 32 && "Unknown width"); 169 return SectionKind::getMergeable4ByteCString(); 170 } 171 } 172 } 173 174 // Otherwise, just drop it into a mergable constant section. If we have 175 // a section for this size, use it, otherwise use the arbitrary sized 176 // mergable section. 177 switch (TM.getTargetData()->getTypeAllocSize(C->getType())) { 178 case 4: return SectionKind::getMergeableConst4(); 179 case 8: return SectionKind::getMergeableConst8(); 180 case 16: return SectionKind::getMergeableConst16(); 181 default: return SectionKind::getMergeableConst(); 182 } 183 184 case Constant::LocalRelocation: 185 // In static relocation model, the linker will resolve all addresses, so 186 // the relocation entries will actually be constants by the time the app 187 // starts up. However, we can't put this into a mergable section, because 188 // the linker doesn't take relocations into consideration when it tries to 189 // merge entries in the section. 190 if (ReloModel == Reloc::Static) 191 return SectionKind::getReadOnly(); 192 193 // Otherwise, the dynamic linker needs to fix it up, put it in the 194 // writable data.rel.local section. 195 return SectionKind::getReadOnlyWithRelLocal(); 196 197 case Constant::GlobalRelocations: 198 // In static relocation model, the linker will resolve all addresses, so 199 // the relocation entries will actually be constants by the time the app 200 // starts up. However, we can't put this into a mergable section, because 201 // the linker doesn't take relocations into consideration when it tries to 202 // merge entries in the section. 203 if (ReloModel == Reloc::Static) 204 return SectionKind::getReadOnly(); 205 206 // Otherwise, the dynamic linker needs to fix it up, put it in the 207 // writable data.rel section. 208 return SectionKind::getReadOnlyWithRel(); 209 } 210 } 211 212 // Okay, this isn't a constant. If the initializer for the global is going 213 // to require a runtime relocation by the dynamic linker, put it into a more 214 // specific section to improve startup time of the app. This coalesces these 215 // globals together onto fewer pages, improving the locality of the dynamic 216 // linker. 217 if (ReloModel == Reloc::Static) 218 return SectionKind::getDataNoRel(); 219 220 switch (C->getRelocationInfo()) { 221 default: llvm_unreachable("unknown relocation info kind"); 222 case Constant::NoRelocation: 223 return SectionKind::getDataNoRel(); 224 case Constant::LocalRelocation: 225 return SectionKind::getDataRelLocal(); 226 case Constant::GlobalRelocations: 227 return SectionKind::getDataRel(); 228 } 229 } 230 231 /// SectionForGlobal - This method computes the appropriate section to emit 232 /// the specified global variable or function definition. This should not 233 /// be passed external (or available externally) globals. 234 const MCSection *TargetLoweringObjectFile:: 235 SectionForGlobal(const GlobalValue *GV, SectionKind Kind, Mangler *Mang, 236 const TargetMachine &TM) const { 237 // Select section name. 238 if (GV->hasSection()) 239 return getExplicitSectionGlobal(GV, Kind, Mang, TM); 240 241 242 // Use default section depending on the 'type' of global 243 return SelectSectionForGlobal(GV, Kind, Mang, TM); 244 } 245 246 247 // Lame default implementation. Calculate the section name for global. 248 const MCSection * 249 TargetLoweringObjectFile::SelectSectionForGlobal(const GlobalValue *GV, 250 SectionKind Kind, 251 Mangler *Mang, 252 const TargetMachine &TM) const{ 253 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 254 255 if (Kind.isText()) 256 return getTextSection(); 257 258 if (Kind.isBSS() && BSSSection != 0) 259 return BSSSection; 260 261 if (Kind.isReadOnly() && ReadOnlySection != 0) 262 return ReadOnlySection; 263 264 return getDataSection(); 265 } 266 267 /// getSectionForConstant - Given a mergable constant with the 268 /// specified size and relocation information, return a section that it 269 /// should be placed in. 270 const MCSection * 271 TargetLoweringObjectFile::getSectionForConstant(SectionKind Kind) const { 272 if (Kind.isReadOnly() && ReadOnlySection != 0) 273 return ReadOnlySection; 274 275 return DataSection; 276 } 277 278 279 280 //===----------------------------------------------------------------------===// 281 // ELF 282 //===----------------------------------------------------------------------===// 283 284 const MCSection *TargetLoweringObjectFileELF:: 285 getELFSection(const char *Name, bool isDirective, SectionKind Kind) const { 286 if (MCSection *S = getContext().GetSection(Name)) 287 return S; 288 return MCSectionELF::Create(Name, isDirective, Kind, getContext()); 289 } 290 291 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx, 292 const TargetMachine &TM) { 293 TargetLoweringObjectFile::Initialize(Ctx, TM); 294 if (!HasCrazyBSS) 295 BSSSection = getELFSection("\t.bss", true, SectionKind::getBSS()); 296 else 297 // PPC/Linux doesn't support the .bss directive, it needs .section .bss. 298 // FIXME: Does .section .bss work everywhere?? 299 // FIXME2: this should just be handle by the section printer. We should get 300 // away from syntactic view of the sections and MCSection should just be a 301 // semantic view. 302 BSSSection = getELFSection("\t.bss", false, SectionKind::getBSS()); 303 304 305 TextSection = getELFSection("\t.text", true, SectionKind::getText()); 306 DataSection = getELFSection("\t.data", true, SectionKind::getDataRel()); 307 ReadOnlySection = 308 getELFSection("\t.rodata", false, SectionKind::getReadOnly()); 309 TLSDataSection = 310 getELFSection("\t.tdata", false, SectionKind::getThreadData()); 311 312 TLSBSSSection = getELFSection("\t.tbss", false, 313 SectionKind::getThreadBSS()); 314 315 DataRelSection = getELFSection("\t.data.rel", false, 316 SectionKind::getDataRel()); 317 DataRelLocalSection = getELFSection("\t.data.rel.local", false, 318 SectionKind::getDataRelLocal()); 319 DataRelROSection = getELFSection("\t.data.rel.ro", false, 320 SectionKind::getReadOnlyWithRel()); 321 DataRelROLocalSection = 322 getELFSection("\t.data.rel.ro.local", false, 323 SectionKind::getReadOnlyWithRelLocal()); 324 325 MergeableConst4Section = getELFSection(".rodata.cst4", false, 326 SectionKind::getMergeableConst4()); 327 MergeableConst8Section = getELFSection(".rodata.cst8", false, 328 SectionKind::getMergeableConst8()); 329 MergeableConst16Section = getELFSection(".rodata.cst16", false, 330 SectionKind::getMergeableConst16()); 331 332 StaticCtorSection = 333 getELFSection(".ctors", false, SectionKind::getDataRel()); 334 StaticDtorSection = 335 getELFSection(".dtors", false, SectionKind::getDataRel()); 336 337 // Exception Handling Sections. 338 339 // FIXME: We're emitting LSDA info into a readonly section on ELF, even though 340 // it contains relocatable pointers. In PIC mode, this is probably a big 341 // runtime hit for C++ apps. Either the contents of the LSDA need to be 342 // adjusted or this should be a data section. 343 LSDASection = 344 getELFSection(".gcc_except_table", false, SectionKind::getReadOnly()); 345 EHFrameSection = 346 getELFSection(".eh_frame", false, SectionKind::getDataRel()); 347 348 // Debug Info Sections. 349 DwarfAbbrevSection = 350 getELFSection(".debug_abbrev", false, SectionKind::getMetadata()); 351 DwarfInfoSection = 352 getELFSection(".debug_info", false, SectionKind::getMetadata()); 353 DwarfLineSection = 354 getELFSection(".debug_line", false, SectionKind::getMetadata()); 355 DwarfFrameSection = 356 getELFSection(".debug_frame", false, SectionKind::getMetadata()); 357 DwarfPubNamesSection = 358 getELFSection(".debug_pubnames", false, SectionKind::getMetadata()); 359 DwarfPubTypesSection = 360 getELFSection(".debug_pubtypes", false, SectionKind::getMetadata()); 361 DwarfStrSection = 362 getELFSection(".debug_str", false, SectionKind::getMetadata()); 363 DwarfLocSection = 364 getELFSection(".debug_loc", false, SectionKind::getMetadata()); 365 DwarfARangesSection = 366 getELFSection(".debug_aranges", false, SectionKind::getMetadata()); 367 DwarfRangesSection = 368 getELFSection(".debug_ranges", false, SectionKind::getMetadata()); 369 DwarfMacroInfoSection = 370 getELFSection(".debug_macinfo", false, SectionKind::getMetadata()); 371 } 372 373 374 static SectionKind 375 getELFKindForNamedSection(const char *Name, SectionKind K) { 376 if (Name[0] != '.') return K; 377 378 // Some lame default implementation based on some magic section names. 379 if (strncmp(Name, ".gnu.linkonce.b.", 16) == 0 || 380 strncmp(Name, ".llvm.linkonce.b.", 17) == 0 || 381 strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 || 382 strncmp(Name, ".llvm.linkonce.sb.", 18) == 0) 383 return SectionKind::getBSS(); 384 385 if (strcmp(Name, ".tdata") == 0 || 386 strncmp(Name, ".tdata.", 7) == 0 || 387 strncmp(Name, ".gnu.linkonce.td.", 17) == 0 || 388 strncmp(Name, ".llvm.linkonce.td.", 18) == 0) 389 return SectionKind::getThreadData(); 390 391 if (strcmp(Name, ".tbss") == 0 || 392 strncmp(Name, ".tbss.", 6) == 0 || 393 strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 || 394 strncmp(Name, ".llvm.linkonce.tb.", 18) == 0) 395 return SectionKind::getThreadBSS(); 396 397 return K; 398 } 399 400 const MCSection *TargetLoweringObjectFileELF:: 401 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 402 Mangler *Mang, const TargetMachine &TM) const { 403 // Infer section flags from the section name if we can. 404 Kind = getELFKindForNamedSection(GV->getSection().c_str(), Kind); 405 406 return getELFSection(GV->getSection().c_str(), false, Kind); 407 } 408 409 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) { 410 if (Kind.isText()) return ".gnu.linkonce.t."; 411 if (Kind.isReadOnly()) return ".gnu.linkonce.r."; 412 413 if (Kind.isThreadData()) return ".gnu.linkonce.td."; 414 if (Kind.isThreadBSS()) return ".gnu.linkonce.tb."; 415 416 if (Kind.isBSS()) return ".gnu.linkonce.b."; 417 if (Kind.isDataNoRel()) return ".gnu.linkonce.d."; 418 if (Kind.isDataRelLocal()) return ".gnu.linkonce.d.rel.local."; 419 if (Kind.isDataRel()) return ".gnu.linkonce.d.rel."; 420 if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local."; 421 422 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 423 return ".gnu.linkonce.d.rel.ro."; 424 } 425 426 const MCSection *TargetLoweringObjectFileELF:: 427 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 428 Mangler *Mang, const TargetMachine &TM) const { 429 430 // If this global is linkonce/weak and the target handles this by emitting it 431 // into a 'uniqued' section name, create and return the section now. 432 if (GV->isWeakForLinker()) { 433 const char *Prefix = getSectionPrefixForUniqueGlobal(Kind); 434 std::string Name = Mang->makeNameProper(GV->getNameStr()); 435 return getELFSection((Prefix+Name).c_str(), false, Kind); 436 } 437 438 if (Kind.isText()) return TextSection; 439 440 if (Kind.isMergeable1ByteCString() || 441 Kind.isMergeable2ByteCString() || 442 Kind.isMergeable4ByteCString()) { 443 444 // We also need alignment here. 445 // FIXME: this is getting the alignment of the character, not the 446 // alignment of the global! 447 unsigned Align = 448 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)); 449 450 const char *SizeSpec = ".rodata.str1."; 451 if (Kind.isMergeable2ByteCString()) 452 SizeSpec = ".rodata.str2."; 453 else if (Kind.isMergeable4ByteCString()) 454 SizeSpec = ".rodata.str4."; 455 else 456 assert(Kind.isMergeable1ByteCString() && "unknown string width"); 457 458 459 std::string Name = SizeSpec + utostr(Align); 460 return getELFSection(Name.c_str(), false, Kind); 461 } 462 463 if (Kind.isMergeableConst()) { 464 if (Kind.isMergeableConst4()) 465 return MergeableConst4Section; 466 if (Kind.isMergeableConst8()) 467 return MergeableConst8Section; 468 if (Kind.isMergeableConst16()) 469 return MergeableConst16Section; 470 return ReadOnlySection; // .const 471 } 472 473 if (Kind.isReadOnly()) return ReadOnlySection; 474 475 if (Kind.isThreadData()) return TLSDataSection; 476 if (Kind.isThreadBSS()) return TLSBSSSection; 477 478 if (Kind.isBSS()) return BSSSection; 479 480 if (Kind.isDataNoRel()) return DataSection; 481 if (Kind.isDataRelLocal()) return DataRelLocalSection; 482 if (Kind.isDataRel()) return DataRelSection; 483 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 484 485 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 486 return DataRelROSection; 487 } 488 489 /// getSectionForConstant - Given a mergeable constant with the 490 /// specified size and relocation information, return a section that it 491 /// should be placed in. 492 const MCSection *TargetLoweringObjectFileELF:: 493 getSectionForConstant(SectionKind Kind) const { 494 if (Kind.isMergeableConst4()) 495 return MergeableConst4Section; 496 if (Kind.isMergeableConst8()) 497 return MergeableConst8Section; 498 if (Kind.isMergeableConst16()) 499 return MergeableConst16Section; 500 if (Kind.isReadOnly()) 501 return ReadOnlySection; 502 503 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 504 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 505 return DataRelROSection; 506 } 507 508 //===----------------------------------------------------------------------===// 509 // MachO 510 //===----------------------------------------------------------------------===// 511 512 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy; 513 514 TargetLoweringObjectFileMachO::~TargetLoweringObjectFileMachO() { 515 // If we have the MachO uniquing map, free it. 516 delete (MachOUniqueMapTy*)UniquingMap; 517 } 518 519 520 const MCSectionMachO *TargetLoweringObjectFileMachO:: 521 getMachOSection(const StringRef &Segment, const StringRef &Section, 522 unsigned TypeAndAttributes, 523 unsigned Reserved2, SectionKind Kind) const { 524 // We unique sections by their segment/section pair. The returned section 525 // may not have the same flags as the requested section, if so this should be 526 // diagnosed by the client as an error. 527 528 // Create the map if it doesn't already exist. 529 if (UniquingMap == 0) 530 UniquingMap = new MachOUniqueMapTy(); 531 MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)UniquingMap; 532 533 // Form the name to look up. 534 SmallString<64> Name; 535 Name.append(Segment.begin(), Segment.end()); 536 Name.push_back(','); 537 Name.append(Section.begin(), Section.end()); 538 539 // Do the lookup, if we have a hit, return it. 540 const MCSectionMachO *&Entry = Map[StringRef(Name.data(), Name.size())]; 541 if (Entry) return Entry; 542 543 // Otherwise, return a new section. 544 return Entry = MCSectionMachO::Create(Segment, Section, TypeAndAttributes, 545 Reserved2, Kind, getContext()); 546 } 547 548 549 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx, 550 const TargetMachine &TM) { 551 TargetLoweringObjectFile::Initialize(Ctx, TM); 552 553 TextSection // .text 554 = getMachOSection("__TEXT", "__text", 555 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 556 SectionKind::getText()); 557 DataSection // .data 558 = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel()); 559 560 CStringSection // .cstring 561 = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS, 562 SectionKind::getMergeable1ByteCString()); 563 UStringSection 564 = getMachOSection("__TEXT","__ustring", 0, 565 SectionKind::getMergeable2ByteCString()); 566 FourByteConstantSection // .literal4 567 = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS, 568 SectionKind::getMergeableConst4()); 569 EightByteConstantSection // .literal8 570 = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS, 571 SectionKind::getMergeableConst8()); 572 573 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back 574 // to using it in -static mode. 575 SixteenByteConstantSection = 0; 576 if (TM.getRelocationModel() != Reloc::Static && 577 TM.getTargetData()->getPointerSize() == 32) 578 SixteenByteConstantSection = // .literal16 579 getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS, 580 SectionKind::getMergeableConst16()); 581 582 ReadOnlySection // .const 583 = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly()); 584 585 TextCoalSection 586 = getMachOSection("__TEXT", "__textcoal_nt", 587 MCSectionMachO::S_COALESCED | 588 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 589 SectionKind::getText()); 590 ConstTextCoalSection 591 = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED, 592 SectionKind::getText()); 593 ConstDataCoalSection 594 = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED, 595 SectionKind::getText()); 596 ConstDataSection // .const_data 597 = getMachOSection("__DATA", "__const", 0, 598 SectionKind::getReadOnlyWithRel()); 599 DataCoalSection 600 = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED, 601 SectionKind::getDataRel()); 602 603 604 LazySymbolPointerSection 605 = getMachOSection("__DATA", "__la_symbol_ptr", 606 MCSectionMachO::S_LAZY_SYMBOL_POINTERS, 607 SectionKind::getMetadata()); 608 NonLazySymbolPointerSection 609 = getMachOSection("__DATA", "__nl_symbol_ptr", 610 MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS, 611 SectionKind::getMetadata()); 612 613 if (TM.getRelocationModel() == Reloc::Static) { 614 StaticCtorSection 615 = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel()); 616 StaticDtorSection 617 = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel()); 618 } else { 619 StaticCtorSection 620 = getMachOSection("__DATA", "__mod_init_func", 621 MCSectionMachO::S_MOD_INIT_FUNC_POINTERS, 622 SectionKind::getDataRel()); 623 StaticDtorSection 624 = getMachOSection("__DATA", "__mod_term_func", 625 MCSectionMachO::S_MOD_TERM_FUNC_POINTERS, 626 SectionKind::getDataRel()); 627 } 628 629 // Exception Handling. 630 LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0, 631 SectionKind::getDataRel()); 632 EHFrameSection = 633 getMachOSection("__TEXT", "__eh_frame", 634 MCSectionMachO::S_COALESCED | 635 MCSectionMachO::S_ATTR_NO_TOC | 636 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS | 637 MCSectionMachO::S_ATTR_LIVE_SUPPORT, 638 SectionKind::getReadOnly()); 639 640 // Debug Information. 641 DwarfAbbrevSection = 642 getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG, 643 SectionKind::getMetadata()); 644 DwarfInfoSection = 645 getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG, 646 SectionKind::getMetadata()); 647 DwarfLineSection = 648 getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG, 649 SectionKind::getMetadata()); 650 DwarfFrameSection = 651 getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG, 652 SectionKind::getMetadata()); 653 DwarfPubNamesSection = 654 getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG, 655 SectionKind::getMetadata()); 656 DwarfPubTypesSection = 657 getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG, 658 SectionKind::getMetadata()); 659 DwarfStrSection = 660 getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG, 661 SectionKind::getMetadata()); 662 DwarfLocSection = 663 getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG, 664 SectionKind::getMetadata()); 665 DwarfARangesSection = 666 getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG, 667 SectionKind::getMetadata()); 668 DwarfRangesSection = 669 getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG, 670 SectionKind::getMetadata()); 671 DwarfMacroInfoSection = 672 getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG, 673 SectionKind::getMetadata()); 674 DwarfDebugInlineSection = 675 getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG, 676 SectionKind::getMetadata()); 677 } 678 679 const MCSection *TargetLoweringObjectFileMachO:: 680 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 681 Mangler *Mang, const TargetMachine &TM) const { 682 // Parse the section specifier and create it if valid. 683 StringRef Segment, Section; 684 unsigned TAA, StubSize; 685 std::string ErrorCode = 686 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, 687 TAA, StubSize); 688 if (!ErrorCode.empty()) { 689 // If invalid, report the error with llvm_report_error. 690 llvm_report_error("Global variable '" + GV->getNameStr() + 691 "' has an invalid section specifier '" + GV->getSection()+ 692 "': " + ErrorCode + "."); 693 // Fall back to dropping it into the data section. 694 return DataSection; 695 } 696 697 // Get the section. 698 const MCSectionMachO *S = 699 getMachOSection(Segment, Section, TAA, StubSize, Kind); 700 701 // Okay, now that we got the section, verify that the TAA & StubSize agree. 702 // If the user declared multiple globals with different section flags, we need 703 // to reject it here. 704 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) { 705 // If invalid, report the error with llvm_report_error. 706 llvm_report_error("Global variable '" + GV->getNameStr() + 707 "' section type or attributes does not match previous" 708 " section specifier"); 709 } 710 711 return S; 712 } 713 714 const MCSection *TargetLoweringObjectFileMachO:: 715 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 716 Mangler *Mang, const TargetMachine &TM) const { 717 assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS"); 718 719 if (Kind.isText()) 720 return GV->isWeakForLinker() ? TextCoalSection : TextSection; 721 722 // If this is weak/linkonce, put this in a coalescable section, either in text 723 // or data depending on if it is writable. 724 if (GV->isWeakForLinker()) { 725 if (Kind.isReadOnly()) 726 return ConstTextCoalSection; 727 return DataCoalSection; 728 } 729 730 // FIXME: Alignment check should be handled by section classifier. 731 if (Kind.isMergeable1ByteCString() || 732 Kind.isMergeable2ByteCString()) { 733 if (TM.getTargetData()->getPreferredAlignment( 734 cast<GlobalVariable>(GV)) < 32) { 735 if (Kind.isMergeable1ByteCString()) 736 return CStringSection; 737 assert(Kind.isMergeable2ByteCString()); 738 return UStringSection; 739 } 740 } 741 742 if (Kind.isMergeableConst()) { 743 if (Kind.isMergeableConst4()) 744 return FourByteConstantSection; 745 if (Kind.isMergeableConst8()) 746 return EightByteConstantSection; 747 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 748 return SixteenByteConstantSection; 749 } 750 751 // Otherwise, if it is readonly, but not something we can specially optimize, 752 // just drop it in .const. 753 if (Kind.isReadOnly()) 754 return ReadOnlySection; 755 756 // If this is marked const, put it into a const section. But if the dynamic 757 // linker needs to write to it, put it in the data segment. 758 if (Kind.isReadOnlyWithRel()) 759 return ConstDataSection; 760 761 // Otherwise, just drop the variable in the normal data section. 762 return DataSection; 763 } 764 765 const MCSection * 766 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { 767 // If this constant requires a relocation, we have to put it in the data 768 // segment, not in the text segment. 769 if (Kind.isDataRel()) 770 return ConstDataSection; 771 772 if (Kind.isMergeableConst4()) 773 return FourByteConstantSection; 774 if (Kind.isMergeableConst8()) 775 return EightByteConstantSection; 776 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 777 return SixteenByteConstantSection; 778 return ReadOnlySection; // .const 779 } 780 781 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide 782 /// not to emit the UsedDirective for some symbols in llvm.used. 783 // FIXME: REMOVE this (rdar://7071300) 784 bool TargetLoweringObjectFileMachO:: 785 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { 786 /// On Darwin, internally linked data beginning with "L" or "l" does not have 787 /// the directive emitted (this occurs in ObjC metadata). 788 if (!GV) return false; 789 790 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. 791 if (GV->hasLocalLinkage() && !isa<Function>(GV)) { 792 // FIXME: ObjC metadata is currently emitted as internal symbols that have 793 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and 794 // this horrible hack can go away. 795 const std::string &Name = Mang->getMangledName(GV); 796 if (Name[0] == 'L' || Name[0] == 'l') 797 return false; 798 } 799 800 return true; 801 } 802 803 804 //===----------------------------------------------------------------------===// 805 // COFF 806 //===----------------------------------------------------------------------===// 807 808 809 const MCSection *TargetLoweringObjectFileCOFF:: 810 getCOFFSection(const char *Name, bool isDirective, SectionKind Kind) const { 811 if (MCSection *S = getContext().GetSection(Name)) 812 return S; 813 return MCSectionCOFF::Create(Name, isDirective, Kind, getContext()); 814 } 815 816 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx, 817 const TargetMachine &TM) { 818 TargetLoweringObjectFile::Initialize(Ctx, TM); 819 TextSection = getCOFFSection("\t.text", true, SectionKind::getText()); 820 DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel()); 821 StaticCtorSection = 822 getCOFFSection(".ctors", false, SectionKind::getDataRel()); 823 StaticDtorSection = 824 getCOFFSection(".dtors", false, SectionKind::getDataRel()); 825 826 827 // Debug info. 828 // FIXME: Don't use 'directive' mode here. 829 DwarfAbbrevSection = 830 getCOFFSection("\t.section\t.debug_abbrev,\"dr\"", 831 true, SectionKind::getMetadata()); 832 DwarfInfoSection = 833 getCOFFSection("\t.section\t.debug_info,\"dr\"", 834 true, SectionKind::getMetadata()); 835 DwarfLineSection = 836 getCOFFSection("\t.section\t.debug_line,\"dr\"", 837 true, SectionKind::getMetadata()); 838 DwarfFrameSection = 839 getCOFFSection("\t.section\t.debug_frame,\"dr\"", 840 true, SectionKind::getMetadata()); 841 DwarfPubNamesSection = 842 getCOFFSection("\t.section\t.debug_pubnames,\"dr\"", 843 true, SectionKind::getMetadata()); 844 DwarfPubTypesSection = 845 getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"", 846 true, SectionKind::getMetadata()); 847 DwarfStrSection = 848 getCOFFSection("\t.section\t.debug_str,\"dr\"", 849 true, SectionKind::getMetadata()); 850 DwarfLocSection = 851 getCOFFSection("\t.section\t.debug_loc,\"dr\"", 852 true, SectionKind::getMetadata()); 853 DwarfARangesSection = 854 getCOFFSection("\t.section\t.debug_aranges,\"dr\"", 855 true, SectionKind::getMetadata()); 856 DwarfRangesSection = 857 getCOFFSection("\t.section\t.debug_ranges,\"dr\"", 858 true, SectionKind::getMetadata()); 859 DwarfMacroInfoSection = 860 getCOFFSection("\t.section\t.debug_macinfo,\"dr\"", 861 true, SectionKind::getMetadata()); 862 } 863 864 const MCSection *TargetLoweringObjectFileCOFF:: 865 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 866 Mangler *Mang, const TargetMachine &TM) const { 867 return getCOFFSection(GV->getSection().c_str(), false, Kind); 868 } 869 870 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { 871 if (Kind.isText()) 872 return ".text$linkonce"; 873 if (Kind.isWriteable()) 874 return ".data$linkonce"; 875 return ".rdata$linkonce"; 876 } 877 878 879 const MCSection *TargetLoweringObjectFileCOFF:: 880 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 881 Mangler *Mang, const TargetMachine &TM) const { 882 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 883 884 // If this global is linkonce/weak and the target handles this by emitting it 885 // into a 'uniqued' section name, create and return the section now. 886 if (GV->isWeakForLinker()) { 887 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); 888 std::string Name = Mang->makeNameProper(GV->getNameStr()); 889 return getCOFFSection((Prefix+Name).c_str(), false, Kind); 890 } 891 892 if (Kind.isText()) 893 return getTextSection(); 894 895 return getDataSection(); 896 } 897 898