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 typedef StringMap<const MCSectionELF*> ELFUniqueMapTy; 284 285 TargetLoweringObjectFileELF::~TargetLoweringObjectFileELF() { 286 // If we have the section uniquing map, free it. 287 delete (ELFUniqueMapTy*)UniquingMap; 288 } 289 290 const MCSection *TargetLoweringObjectFileELF:: 291 getELFSection(const char *Name, bool isDirective, SectionKind Kind) const { 292 // Create the map if it doesn't already exist. 293 if (UniquingMap == 0) 294 UniquingMap = new ELFUniqueMapTy(); 295 ELFUniqueMapTy &Map = *(ELFUniqueMapTy*)UniquingMap; 296 297 // Do the lookup, if we have a hit, return it. 298 const MCSectionELF *&Entry = Map[Name]; 299 if (Entry) return Entry; 300 301 return Entry = MCSectionELF::Create(Name, isDirective, Kind, getContext()); 302 } 303 304 void TargetLoweringObjectFileELF::Initialize(MCContext &Ctx, 305 const TargetMachine &TM) { 306 TargetLoweringObjectFile::Initialize(Ctx, TM); 307 if (!HasCrazyBSS) 308 BSSSection = getELFSection("\t.bss", true, SectionKind::getBSS()); 309 else 310 // PPC/Linux doesn't support the .bss directive, it needs .section .bss. 311 // FIXME: Does .section .bss work everywhere?? 312 // FIXME2: this should just be handle by the section printer. We should get 313 // away from syntactic view of the sections and MCSection should just be a 314 // semantic view. 315 BSSSection = getELFSection("\t.bss", false, SectionKind::getBSS()); 316 317 318 TextSection = getELFSection("\t.text", true, SectionKind::getText()); 319 DataSection = getELFSection("\t.data", true, SectionKind::getDataRel()); 320 ReadOnlySection = 321 getELFSection("\t.rodata", false, SectionKind::getReadOnly()); 322 TLSDataSection = 323 getELFSection("\t.tdata", false, SectionKind::getThreadData()); 324 325 TLSBSSSection = getELFSection("\t.tbss", false, 326 SectionKind::getThreadBSS()); 327 328 DataRelSection = getELFSection("\t.data.rel", false, 329 SectionKind::getDataRel()); 330 DataRelLocalSection = getELFSection("\t.data.rel.local", false, 331 SectionKind::getDataRelLocal()); 332 DataRelROSection = getELFSection("\t.data.rel.ro", false, 333 SectionKind::getReadOnlyWithRel()); 334 DataRelROLocalSection = 335 getELFSection("\t.data.rel.ro.local", false, 336 SectionKind::getReadOnlyWithRelLocal()); 337 338 MergeableConst4Section = getELFSection(".rodata.cst4", false, 339 SectionKind::getMergeableConst4()); 340 MergeableConst8Section = getELFSection(".rodata.cst8", false, 341 SectionKind::getMergeableConst8()); 342 MergeableConst16Section = getELFSection(".rodata.cst16", false, 343 SectionKind::getMergeableConst16()); 344 345 StaticCtorSection = 346 getELFSection(".ctors", false, SectionKind::getDataRel()); 347 StaticDtorSection = 348 getELFSection(".dtors", false, SectionKind::getDataRel()); 349 350 // Exception Handling Sections. 351 352 // FIXME: We're emitting LSDA info into a readonly section on ELF, even though 353 // it contains relocatable pointers. In PIC mode, this is probably a big 354 // runtime hit for C++ apps. Either the contents of the LSDA need to be 355 // adjusted or this should be a data section. 356 LSDASection = 357 getELFSection(".gcc_except_table", false, SectionKind::getReadOnly()); 358 EHFrameSection = 359 getELFSection(".eh_frame", false, SectionKind::getDataRel()); 360 361 // Debug Info Sections. 362 DwarfAbbrevSection = 363 getELFSection(".debug_abbrev", false, SectionKind::getMetadata()); 364 DwarfInfoSection = 365 getELFSection(".debug_info", false, SectionKind::getMetadata()); 366 DwarfLineSection = 367 getELFSection(".debug_line", false, SectionKind::getMetadata()); 368 DwarfFrameSection = 369 getELFSection(".debug_frame", false, SectionKind::getMetadata()); 370 DwarfPubNamesSection = 371 getELFSection(".debug_pubnames", false, SectionKind::getMetadata()); 372 DwarfPubTypesSection = 373 getELFSection(".debug_pubtypes", false, SectionKind::getMetadata()); 374 DwarfStrSection = 375 getELFSection(".debug_str", false, SectionKind::getMetadata()); 376 DwarfLocSection = 377 getELFSection(".debug_loc", false, SectionKind::getMetadata()); 378 DwarfARangesSection = 379 getELFSection(".debug_aranges", false, SectionKind::getMetadata()); 380 DwarfRangesSection = 381 getELFSection(".debug_ranges", false, SectionKind::getMetadata()); 382 DwarfMacroInfoSection = 383 getELFSection(".debug_macinfo", false, SectionKind::getMetadata()); 384 } 385 386 387 static SectionKind 388 getELFKindForNamedSection(const char *Name, SectionKind K) { 389 if (Name[0] != '.') return K; 390 391 // Some lame default implementation based on some magic section names. 392 if (strncmp(Name, ".gnu.linkonce.b.", 16) == 0 || 393 strncmp(Name, ".llvm.linkonce.b.", 17) == 0 || 394 strncmp(Name, ".gnu.linkonce.sb.", 17) == 0 || 395 strncmp(Name, ".llvm.linkonce.sb.", 18) == 0) 396 return SectionKind::getBSS(); 397 398 if (strcmp(Name, ".tdata") == 0 || 399 strncmp(Name, ".tdata.", 7) == 0 || 400 strncmp(Name, ".gnu.linkonce.td.", 17) == 0 || 401 strncmp(Name, ".llvm.linkonce.td.", 18) == 0) 402 return SectionKind::getThreadData(); 403 404 if (strcmp(Name, ".tbss") == 0 || 405 strncmp(Name, ".tbss.", 6) == 0 || 406 strncmp(Name, ".gnu.linkonce.tb.", 17) == 0 || 407 strncmp(Name, ".llvm.linkonce.tb.", 18) == 0) 408 return SectionKind::getThreadBSS(); 409 410 return K; 411 } 412 413 const MCSection *TargetLoweringObjectFileELF:: 414 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 415 Mangler *Mang, const TargetMachine &TM) const { 416 // Infer section flags from the section name if we can. 417 Kind = getELFKindForNamedSection(GV->getSection().c_str(), Kind); 418 419 return getELFSection(GV->getSection().c_str(), false, Kind); 420 } 421 422 static const char *getSectionPrefixForUniqueGlobal(SectionKind Kind) { 423 if (Kind.isText()) return ".gnu.linkonce.t."; 424 if (Kind.isReadOnly()) return ".gnu.linkonce.r."; 425 426 if (Kind.isThreadData()) return ".gnu.linkonce.td."; 427 if (Kind.isThreadBSS()) return ".gnu.linkonce.tb."; 428 429 if (Kind.isBSS()) return ".gnu.linkonce.b."; 430 if (Kind.isDataNoRel()) return ".gnu.linkonce.d."; 431 if (Kind.isDataRelLocal()) return ".gnu.linkonce.d.rel.local."; 432 if (Kind.isDataRel()) return ".gnu.linkonce.d.rel."; 433 if (Kind.isReadOnlyWithRelLocal()) return ".gnu.linkonce.d.rel.ro.local."; 434 435 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 436 return ".gnu.linkonce.d.rel.ro."; 437 } 438 439 const MCSection *TargetLoweringObjectFileELF:: 440 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 441 Mangler *Mang, const TargetMachine &TM) const { 442 443 // If this global is linkonce/weak and the target handles this by emitting it 444 // into a 'uniqued' section name, create and return the section now. 445 if (GV->isWeakForLinker()) { 446 const char *Prefix = getSectionPrefixForUniqueGlobal(Kind); 447 std::string Name = Mang->makeNameProper(GV->getNameStr()); 448 return getELFSection((Prefix+Name).c_str(), false, Kind); 449 } 450 451 if (Kind.isText()) return TextSection; 452 453 if (Kind.isMergeable1ByteCString() || 454 Kind.isMergeable2ByteCString() || 455 Kind.isMergeable4ByteCString()) { 456 457 // We also need alignment here. 458 // FIXME: this is getting the alignment of the character, not the 459 // alignment of the global! 460 unsigned Align = 461 TM.getTargetData()->getPreferredAlignment(cast<GlobalVariable>(GV)); 462 463 const char *SizeSpec = ".rodata.str1."; 464 if (Kind.isMergeable2ByteCString()) 465 SizeSpec = ".rodata.str2."; 466 else if (Kind.isMergeable4ByteCString()) 467 SizeSpec = ".rodata.str4."; 468 else 469 assert(Kind.isMergeable1ByteCString() && "unknown string width"); 470 471 472 std::string Name = SizeSpec + utostr(Align); 473 return getELFSection(Name.c_str(), false, Kind); 474 } 475 476 if (Kind.isMergeableConst()) { 477 if (Kind.isMergeableConst4()) 478 return MergeableConst4Section; 479 if (Kind.isMergeableConst8()) 480 return MergeableConst8Section; 481 if (Kind.isMergeableConst16()) 482 return MergeableConst16Section; 483 return ReadOnlySection; // .const 484 } 485 486 if (Kind.isReadOnly()) return ReadOnlySection; 487 488 if (Kind.isThreadData()) return TLSDataSection; 489 if (Kind.isThreadBSS()) return TLSBSSSection; 490 491 if (Kind.isBSS()) return BSSSection; 492 493 if (Kind.isDataNoRel()) return DataSection; 494 if (Kind.isDataRelLocal()) return DataRelLocalSection; 495 if (Kind.isDataRel()) return DataRelSection; 496 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 497 498 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 499 return DataRelROSection; 500 } 501 502 /// getSectionForConstant - Given a mergeable constant with the 503 /// specified size and relocation information, return a section that it 504 /// should be placed in. 505 const MCSection *TargetLoweringObjectFileELF:: 506 getSectionForConstant(SectionKind Kind) const { 507 if (Kind.isMergeableConst4()) 508 return MergeableConst4Section; 509 if (Kind.isMergeableConst8()) 510 return MergeableConst8Section; 511 if (Kind.isMergeableConst16()) 512 return MergeableConst16Section; 513 if (Kind.isReadOnly()) 514 return ReadOnlySection; 515 516 if (Kind.isReadOnlyWithRelLocal()) return DataRelROLocalSection; 517 assert(Kind.isReadOnlyWithRel() && "Unknown section kind"); 518 return DataRelROSection; 519 } 520 521 //===----------------------------------------------------------------------===// 522 // MachO 523 //===----------------------------------------------------------------------===// 524 525 typedef StringMap<const MCSectionMachO*> MachOUniqueMapTy; 526 527 TargetLoweringObjectFileMachO::~TargetLoweringObjectFileMachO() { 528 // If we have the MachO uniquing map, free it. 529 delete (MachOUniqueMapTy*)UniquingMap; 530 } 531 532 533 const MCSectionMachO *TargetLoweringObjectFileMachO:: 534 getMachOSection(const StringRef &Segment, const StringRef &Section, 535 unsigned TypeAndAttributes, 536 unsigned Reserved2, SectionKind Kind) const { 537 // We unique sections by their segment/section pair. The returned section 538 // may not have the same flags as the requested section, if so this should be 539 // diagnosed by the client as an error. 540 541 // Create the map if it doesn't already exist. 542 if (UniquingMap == 0) 543 UniquingMap = new MachOUniqueMapTy(); 544 MachOUniqueMapTy &Map = *(MachOUniqueMapTy*)UniquingMap; 545 546 // Form the name to look up. 547 SmallString<64> Name; 548 Name.append(Segment.begin(), Segment.end()); 549 Name.push_back(','); 550 Name.append(Section.begin(), Section.end()); 551 552 // Do the lookup, if we have a hit, return it. 553 const MCSectionMachO *&Entry = Map[StringRef(Name.data(), Name.size())]; 554 if (Entry) return Entry; 555 556 // Otherwise, return a new section. 557 return Entry = MCSectionMachO::Create(Segment, Section, TypeAndAttributes, 558 Reserved2, Kind, getContext()); 559 } 560 561 562 void TargetLoweringObjectFileMachO::Initialize(MCContext &Ctx, 563 const TargetMachine &TM) { 564 TargetLoweringObjectFile::Initialize(Ctx, TM); 565 566 TextSection // .text 567 = getMachOSection("__TEXT", "__text", 568 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 569 SectionKind::getText()); 570 DataSection // .data 571 = getMachOSection("__DATA", "__data", 0, SectionKind::getDataRel()); 572 573 CStringSection // .cstring 574 = getMachOSection("__TEXT", "__cstring", MCSectionMachO::S_CSTRING_LITERALS, 575 SectionKind::getMergeable1ByteCString()); 576 UStringSection 577 = getMachOSection("__TEXT","__ustring", 0, 578 SectionKind::getMergeable2ByteCString()); 579 FourByteConstantSection // .literal4 580 = getMachOSection("__TEXT", "__literal4", MCSectionMachO::S_4BYTE_LITERALS, 581 SectionKind::getMergeableConst4()); 582 EightByteConstantSection // .literal8 583 = getMachOSection("__TEXT", "__literal8", MCSectionMachO::S_8BYTE_LITERALS, 584 SectionKind::getMergeableConst8()); 585 586 // ld_classic doesn't support .literal16 in 32-bit mode, and ld64 falls back 587 // to using it in -static mode. 588 SixteenByteConstantSection = 0; 589 if (TM.getRelocationModel() != Reloc::Static && 590 TM.getTargetData()->getPointerSize() == 32) 591 SixteenByteConstantSection = // .literal16 592 getMachOSection("__TEXT", "__literal16",MCSectionMachO::S_16BYTE_LITERALS, 593 SectionKind::getMergeableConst16()); 594 595 ReadOnlySection // .const 596 = getMachOSection("__TEXT", "__const", 0, SectionKind::getReadOnly()); 597 598 TextCoalSection 599 = getMachOSection("__TEXT", "__textcoal_nt", 600 MCSectionMachO::S_COALESCED | 601 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 602 SectionKind::getText()); 603 ConstTextCoalSection 604 = getMachOSection("__TEXT", "__const_coal", MCSectionMachO::S_COALESCED, 605 SectionKind::getText()); 606 ConstDataCoalSection 607 = getMachOSection("__DATA","__const_coal", MCSectionMachO::S_COALESCED, 608 SectionKind::getText()); 609 ConstDataSection // .const_data 610 = getMachOSection("__DATA", "__const", 0, 611 SectionKind::getReadOnlyWithRel()); 612 DataCoalSection 613 = getMachOSection("__DATA","__datacoal_nt", MCSectionMachO::S_COALESCED, 614 SectionKind::getDataRel()); 615 616 617 LazySymbolPointerSection 618 = getMachOSection("__DATA", "__la_symbol_ptr", 619 MCSectionMachO::S_LAZY_SYMBOL_POINTERS, 620 SectionKind::getMetadata()); 621 NonLazySymbolPointerSection 622 = getMachOSection("__DATA", "__nl_symbol_ptr", 623 MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS, 624 SectionKind::getMetadata()); 625 626 if (TM.getRelocationModel() == Reloc::Static) { 627 StaticCtorSection 628 = getMachOSection("__TEXT", "__constructor", 0,SectionKind::getDataRel()); 629 StaticDtorSection 630 = getMachOSection("__TEXT", "__destructor", 0, SectionKind::getDataRel()); 631 } else { 632 StaticCtorSection 633 = getMachOSection("__DATA", "__mod_init_func", 634 MCSectionMachO::S_MOD_INIT_FUNC_POINTERS, 635 SectionKind::getDataRel()); 636 StaticDtorSection 637 = getMachOSection("__DATA", "__mod_term_func", 638 MCSectionMachO::S_MOD_TERM_FUNC_POINTERS, 639 SectionKind::getDataRel()); 640 } 641 642 // Exception Handling. 643 LSDASection = getMachOSection("__DATA", "__gcc_except_tab", 0, 644 SectionKind::getDataRel()); 645 EHFrameSection = 646 getMachOSection("__TEXT", "__eh_frame", 647 MCSectionMachO::S_COALESCED | 648 MCSectionMachO::S_ATTR_NO_TOC | 649 MCSectionMachO::S_ATTR_STRIP_STATIC_SYMS | 650 MCSectionMachO::S_ATTR_LIVE_SUPPORT, 651 SectionKind::getReadOnly()); 652 653 // Debug Information. 654 DwarfAbbrevSection = 655 getMachOSection("__DWARF", "__debug_abbrev", MCSectionMachO::S_ATTR_DEBUG, 656 SectionKind::getMetadata()); 657 DwarfInfoSection = 658 getMachOSection("__DWARF", "__debug_info", MCSectionMachO::S_ATTR_DEBUG, 659 SectionKind::getMetadata()); 660 DwarfLineSection = 661 getMachOSection("__DWARF", "__debug_line", MCSectionMachO::S_ATTR_DEBUG, 662 SectionKind::getMetadata()); 663 DwarfFrameSection = 664 getMachOSection("__DWARF", "__debug_frame", MCSectionMachO::S_ATTR_DEBUG, 665 SectionKind::getMetadata()); 666 DwarfPubNamesSection = 667 getMachOSection("__DWARF", "__debug_pubnames", MCSectionMachO::S_ATTR_DEBUG, 668 SectionKind::getMetadata()); 669 DwarfPubTypesSection = 670 getMachOSection("__DWARF", "__debug_pubtypes", MCSectionMachO::S_ATTR_DEBUG, 671 SectionKind::getMetadata()); 672 DwarfStrSection = 673 getMachOSection("__DWARF", "__debug_str", MCSectionMachO::S_ATTR_DEBUG, 674 SectionKind::getMetadata()); 675 DwarfLocSection = 676 getMachOSection("__DWARF", "__debug_loc", MCSectionMachO::S_ATTR_DEBUG, 677 SectionKind::getMetadata()); 678 DwarfARangesSection = 679 getMachOSection("__DWARF", "__debug_aranges", MCSectionMachO::S_ATTR_DEBUG, 680 SectionKind::getMetadata()); 681 DwarfRangesSection = 682 getMachOSection("__DWARF", "__debug_ranges", MCSectionMachO::S_ATTR_DEBUG, 683 SectionKind::getMetadata()); 684 DwarfMacroInfoSection = 685 getMachOSection("__DWARF", "__debug_macinfo", MCSectionMachO::S_ATTR_DEBUG, 686 SectionKind::getMetadata()); 687 DwarfDebugInlineSection = 688 getMachOSection("__DWARF", "__debug_inlined", MCSectionMachO::S_ATTR_DEBUG, 689 SectionKind::getMetadata()); 690 } 691 692 const MCSection *TargetLoweringObjectFileMachO:: 693 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 694 Mangler *Mang, const TargetMachine &TM) const { 695 // Parse the section specifier and create it if valid. 696 StringRef Segment, Section; 697 unsigned TAA, StubSize; 698 std::string ErrorCode = 699 MCSectionMachO::ParseSectionSpecifier(GV->getSection(), Segment, Section, 700 TAA, StubSize); 701 if (!ErrorCode.empty()) { 702 // If invalid, report the error with llvm_report_error. 703 llvm_report_error("Global variable '" + GV->getNameStr() + 704 "' has an invalid section specifier '" + GV->getSection()+ 705 "': " + ErrorCode + "."); 706 // Fall back to dropping it into the data section. 707 return DataSection; 708 } 709 710 // Get the section. 711 const MCSectionMachO *S = 712 getMachOSection(Segment, Section, TAA, StubSize, Kind); 713 714 // Okay, now that we got the section, verify that the TAA & StubSize agree. 715 // If the user declared multiple globals with different section flags, we need 716 // to reject it here. 717 if (S->getTypeAndAttributes() != TAA || S->getStubSize() != StubSize) { 718 // If invalid, report the error with llvm_report_error. 719 llvm_report_error("Global variable '" + GV->getNameStr() + 720 "' section type or attributes does not match previous" 721 " section specifier"); 722 } 723 724 return S; 725 } 726 727 const MCSection *TargetLoweringObjectFileMachO:: 728 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 729 Mangler *Mang, const TargetMachine &TM) const { 730 assert(!Kind.isThreadLocal() && "Darwin doesn't support TLS"); 731 732 if (Kind.isText()) 733 return GV->isWeakForLinker() ? TextCoalSection : TextSection; 734 735 // If this is weak/linkonce, put this in a coalescable section, either in text 736 // or data depending on if it is writable. 737 if (GV->isWeakForLinker()) { 738 if (Kind.isReadOnly()) 739 return ConstTextCoalSection; 740 return DataCoalSection; 741 } 742 743 // FIXME: Alignment check should be handled by section classifier. 744 if (Kind.isMergeable1ByteCString() || 745 Kind.isMergeable2ByteCString()) { 746 if (TM.getTargetData()->getPreferredAlignment( 747 cast<GlobalVariable>(GV)) < 32) { 748 if (Kind.isMergeable1ByteCString()) 749 return CStringSection; 750 assert(Kind.isMergeable2ByteCString()); 751 return UStringSection; 752 } 753 } 754 755 if (Kind.isMergeableConst()) { 756 if (Kind.isMergeableConst4()) 757 return FourByteConstantSection; 758 if (Kind.isMergeableConst8()) 759 return EightByteConstantSection; 760 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 761 return SixteenByteConstantSection; 762 } 763 764 // Otherwise, if it is readonly, but not something we can specially optimize, 765 // just drop it in .const. 766 if (Kind.isReadOnly()) 767 return ReadOnlySection; 768 769 // If this is marked const, put it into a const section. But if the dynamic 770 // linker needs to write to it, put it in the data segment. 771 if (Kind.isReadOnlyWithRel()) 772 return ConstDataSection; 773 774 // Otherwise, just drop the variable in the normal data section. 775 return DataSection; 776 } 777 778 const MCSection * 779 TargetLoweringObjectFileMachO::getSectionForConstant(SectionKind Kind) const { 780 // If this constant requires a relocation, we have to put it in the data 781 // segment, not in the text segment. 782 if (Kind.isDataRel()) 783 return ConstDataSection; 784 785 if (Kind.isMergeableConst4()) 786 return FourByteConstantSection; 787 if (Kind.isMergeableConst8()) 788 return EightByteConstantSection; 789 if (Kind.isMergeableConst16() && SixteenByteConstantSection) 790 return SixteenByteConstantSection; 791 return ReadOnlySection; // .const 792 } 793 794 /// shouldEmitUsedDirectiveFor - This hook allows targets to selectively decide 795 /// not to emit the UsedDirective for some symbols in llvm.used. 796 // FIXME: REMOVE this (rdar://7071300) 797 bool TargetLoweringObjectFileMachO:: 798 shouldEmitUsedDirectiveFor(const GlobalValue *GV, Mangler *Mang) const { 799 /// On Darwin, internally linked data beginning with "L" or "l" does not have 800 /// the directive emitted (this occurs in ObjC metadata). 801 if (!GV) return false; 802 803 // Check whether the mangled name has the "Private" or "LinkerPrivate" prefix. 804 if (GV->hasLocalLinkage() && !isa<Function>(GV)) { 805 // FIXME: ObjC metadata is currently emitted as internal symbols that have 806 // \1L and \0l prefixes on them. Fix them to be Private/LinkerPrivate and 807 // this horrible hack can go away. 808 const std::string &Name = Mang->getMangledName(GV); 809 if (Name[0] == 'L' || Name[0] == 'l') 810 return false; 811 } 812 813 return true; 814 } 815 816 817 //===----------------------------------------------------------------------===// 818 // COFF 819 //===----------------------------------------------------------------------===// 820 821 typedef StringMap<const MCSectionCOFF*> COFFUniqueMapTy; 822 823 TargetLoweringObjectFileCOFF::~TargetLoweringObjectFileCOFF() { 824 delete (COFFUniqueMapTy*)UniquingMap; 825 } 826 827 828 const MCSection *TargetLoweringObjectFileCOFF:: 829 getCOFFSection(const char *Name, bool isDirective, SectionKind Kind) const { 830 // Create the map if it doesn't already exist. 831 if (UniquingMap == 0) 832 UniquingMap = new MachOUniqueMapTy(); 833 COFFUniqueMapTy &Map = *(COFFUniqueMapTy*)UniquingMap; 834 835 // Do the lookup, if we have a hit, return it. 836 const MCSectionCOFF *&Entry = Map[Name]; 837 if (Entry) return Entry; 838 839 return Entry = MCSectionCOFF::Create(Name, isDirective, Kind, getContext()); 840 } 841 842 void TargetLoweringObjectFileCOFF::Initialize(MCContext &Ctx, 843 const TargetMachine &TM) { 844 TargetLoweringObjectFile::Initialize(Ctx, TM); 845 TextSection = getCOFFSection("\t.text", true, SectionKind::getText()); 846 DataSection = getCOFFSection("\t.data", true, SectionKind::getDataRel()); 847 StaticCtorSection = 848 getCOFFSection(".ctors", false, SectionKind::getDataRel()); 849 StaticDtorSection = 850 getCOFFSection(".dtors", false, SectionKind::getDataRel()); 851 852 853 // Debug info. 854 // FIXME: Don't use 'directive' mode here. 855 DwarfAbbrevSection = 856 getCOFFSection("\t.section\t.debug_abbrev,\"dr\"", 857 true, SectionKind::getMetadata()); 858 DwarfInfoSection = 859 getCOFFSection("\t.section\t.debug_info,\"dr\"", 860 true, SectionKind::getMetadata()); 861 DwarfLineSection = 862 getCOFFSection("\t.section\t.debug_line,\"dr\"", 863 true, SectionKind::getMetadata()); 864 DwarfFrameSection = 865 getCOFFSection("\t.section\t.debug_frame,\"dr\"", 866 true, SectionKind::getMetadata()); 867 DwarfPubNamesSection = 868 getCOFFSection("\t.section\t.debug_pubnames,\"dr\"", 869 true, SectionKind::getMetadata()); 870 DwarfPubTypesSection = 871 getCOFFSection("\t.section\t.debug_pubtypes,\"dr\"", 872 true, SectionKind::getMetadata()); 873 DwarfStrSection = 874 getCOFFSection("\t.section\t.debug_str,\"dr\"", 875 true, SectionKind::getMetadata()); 876 DwarfLocSection = 877 getCOFFSection("\t.section\t.debug_loc,\"dr\"", 878 true, SectionKind::getMetadata()); 879 DwarfARangesSection = 880 getCOFFSection("\t.section\t.debug_aranges,\"dr\"", 881 true, SectionKind::getMetadata()); 882 DwarfRangesSection = 883 getCOFFSection("\t.section\t.debug_ranges,\"dr\"", 884 true, SectionKind::getMetadata()); 885 DwarfMacroInfoSection = 886 getCOFFSection("\t.section\t.debug_macinfo,\"dr\"", 887 true, SectionKind::getMetadata()); 888 } 889 890 const MCSection *TargetLoweringObjectFileCOFF:: 891 getExplicitSectionGlobal(const GlobalValue *GV, SectionKind Kind, 892 Mangler *Mang, const TargetMachine &TM) const { 893 return getCOFFSection(GV->getSection().c_str(), false, Kind); 894 } 895 896 static const char *getCOFFSectionPrefixForUniqueGlobal(SectionKind Kind) { 897 if (Kind.isText()) 898 return ".text$linkonce"; 899 if (Kind.isWriteable()) 900 return ".data$linkonce"; 901 return ".rdata$linkonce"; 902 } 903 904 905 const MCSection *TargetLoweringObjectFileCOFF:: 906 SelectSectionForGlobal(const GlobalValue *GV, SectionKind Kind, 907 Mangler *Mang, const TargetMachine &TM) const { 908 assert(!Kind.isThreadLocal() && "Doesn't support TLS"); 909 910 // If this global is linkonce/weak and the target handles this by emitting it 911 // into a 'uniqued' section name, create and return the section now. 912 if (GV->isWeakForLinker()) { 913 const char *Prefix = getCOFFSectionPrefixForUniqueGlobal(Kind); 914 std::string Name = Mang->makeNameProper(GV->getNameStr()); 915 return getCOFFSection((Prefix+Name).c_str(), false, Kind); 916 } 917 918 if (Kind.isText()) 919 return getTextSection(); 920 921 return getDataSection(); 922 } 923 924