1 //===-- X86MachObjectWriter.cpp - X86 Mach-O Writer -----------------------===// 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 #include "MCTargetDesc/X86MCTargetDesc.h" 11 #include "MCTargetDesc/X86FixupKinds.h" 12 #include "llvm/ADT/Twine.h" 13 #include "llvm/MC/MCAsmLayout.h" 14 #include "llvm/MC/MCAssembler.h" 15 #include "llvm/MC/MCContext.h" 16 #include "llvm/MC/MCMachObjectWriter.h" 17 #include "llvm/MC/MCSectionMachO.h" 18 #include "llvm/MC/MCValue.h" 19 #include "llvm/Support/ErrorHandling.h" 20 #include "llvm/Support/Format.h" 21 #include "llvm/Support/MachO.h" 22 23 using namespace llvm; 24 25 namespace { 26 class X86MachObjectWriter : public MCMachObjectTargetWriter { 27 bool RecordScatteredRelocation(MachObjectWriter *Writer, 28 const MCAssembler &Asm, 29 const MCAsmLayout &Layout, 30 const MCFragment *Fragment, 31 const MCFixup &Fixup, 32 MCValue Target, 33 unsigned Log2Size, 34 uint64_t &FixedValue); 35 void RecordTLVPRelocation(MachObjectWriter *Writer, 36 const MCAssembler &Asm, 37 const MCAsmLayout &Layout, 38 const MCFragment *Fragment, 39 const MCFixup &Fixup, 40 MCValue Target, 41 uint64_t &FixedValue); 42 43 void RecordX86Relocation(MachObjectWriter *Writer, 44 const MCAssembler &Asm, 45 const MCAsmLayout &Layout, 46 const MCFragment *Fragment, 47 const MCFixup &Fixup, 48 MCValue Target, 49 uint64_t &FixedValue); 50 void RecordX86_64Relocation(MachObjectWriter *Writer, 51 const MCAssembler &Asm, 52 const MCAsmLayout &Layout, 53 const MCFragment *Fragment, 54 const MCFixup &Fixup, 55 MCValue Target, 56 uint64_t &FixedValue); 57 public: 58 X86MachObjectWriter(bool Is64Bit, uint32_t CPUType, 59 uint32_t CPUSubtype) 60 : MCMachObjectTargetWriter(Is64Bit, CPUType, CPUSubtype, 61 /*UseAggressiveSymbolFolding=*/Is64Bit) {} 62 63 void RecordRelocation(MachObjectWriter *Writer, 64 const MCAssembler &Asm, const MCAsmLayout &Layout, 65 const MCFragment *Fragment, const MCFixup &Fixup, 66 MCValue Target, uint64_t &FixedValue) override { 67 if (Writer->is64Bit()) 68 RecordX86_64Relocation(Writer, Asm, Layout, Fragment, Fixup, Target, 69 FixedValue); 70 else 71 RecordX86Relocation(Writer, Asm, Layout, Fragment, Fixup, Target, 72 FixedValue); 73 } 74 }; 75 } 76 77 static bool isFixupKindRIPRel(unsigned Kind) { 78 return Kind == X86::reloc_riprel_4byte || 79 Kind == X86::reloc_riprel_4byte_movq_load; 80 } 81 82 static unsigned getFixupKindLog2Size(unsigned Kind) { 83 switch (Kind) { 84 default: 85 llvm_unreachable("invalid fixup kind!"); 86 case FK_PCRel_1: 87 case FK_Data_1: return 0; 88 case FK_PCRel_2: 89 case FK_Data_2: return 1; 90 case FK_PCRel_4: 91 // FIXME: Remove these!!! 92 case X86::reloc_riprel_4byte: 93 case X86::reloc_riprel_4byte_movq_load: 94 case X86::reloc_signed_4byte: 95 case FK_Data_4: return 2; 96 case FK_Data_8: return 3; 97 } 98 } 99 100 void X86MachObjectWriter::RecordX86_64Relocation(MachObjectWriter *Writer, 101 const MCAssembler &Asm, 102 const MCAsmLayout &Layout, 103 const MCFragment *Fragment, 104 const MCFixup &Fixup, 105 MCValue Target, 106 uint64_t &FixedValue) { 107 unsigned IsPCRel = Writer->isFixupKindPCRel(Asm, Fixup.getKind()); 108 unsigned IsRIPRel = isFixupKindRIPRel(Fixup.getKind()); 109 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind()); 110 111 // See <reloc.h>. 112 uint32_t FixupOffset = 113 Layout.getFragmentOffset(Fragment) + Fixup.getOffset(); 114 uint32_t FixupAddress = 115 Writer->getFragmentAddress(Fragment, Layout) + Fixup.getOffset(); 116 int64_t Value = 0; 117 unsigned Index = 0; 118 unsigned IsExtern = 0; 119 unsigned Type = 0; 120 121 Value = Target.getConstant(); 122 123 if (IsPCRel) { 124 // Compensate for the relocation offset, Darwin x86_64 relocations only have 125 // the addend and appear to have attempted to define it to be the actual 126 // expression addend without the PCrel bias. However, instructions with data 127 // following the relocation are not accommodated for (see comment below 128 // regarding SIGNED{1,2,4}), so it isn't exactly that either. 129 Value += 1LL << Log2Size; 130 } 131 132 if (Target.isAbsolute()) { // constant 133 // SymbolNum of 0 indicates the absolute section. 134 Type = MachO::X86_64_RELOC_UNSIGNED; 135 Index = 0; 136 137 // FIXME: I believe this is broken, I don't think the linker can understand 138 // it. I think it would require a local relocation, but I'm not sure if that 139 // would work either. The official way to get an absolute PCrel relocation 140 // is to use an absolute symbol (which we don't support yet). 141 if (IsPCRel) { 142 IsExtern = 1; 143 Type = MachO::X86_64_RELOC_BRANCH; 144 } 145 } else if (Target.getSymB()) { // A - B + constant 146 const MCSymbol *A = &Target.getSymA()->getSymbol(); 147 if (A->isTemporary()) 148 A = &A->AliasedSymbol(); 149 const MCSymbolData &A_SD = Asm.getSymbolData(*A); 150 const MCSymbolData *A_Base = Asm.getAtom(&A_SD); 151 152 const MCSymbol *B = &Target.getSymB()->getSymbol(); 153 if (B->isTemporary()) 154 B = &B->AliasedSymbol(); 155 const MCSymbolData &B_SD = Asm.getSymbolData(*B); 156 const MCSymbolData *B_Base = Asm.getAtom(&B_SD); 157 158 // Neither symbol can be modified. 159 if (Target.getSymA()->getKind() != MCSymbolRefExpr::VK_None || 160 Target.getSymB()->getKind() != MCSymbolRefExpr::VK_None) 161 report_fatal_error("unsupported relocation of modified symbol", false); 162 163 // We don't support PCrel relocations of differences. Darwin 'as' doesn't 164 // implement most of these correctly. 165 if (IsPCRel) 166 report_fatal_error("unsupported pc-relative relocation of difference", 167 false); 168 169 // The support for the situation where one or both of the symbols would 170 // require a local relocation is handled just like if the symbols were 171 // external. This is certainly used in the case of debug sections where the 172 // section has only temporary symbols and thus the symbols don't have base 173 // symbols. This is encoded using the section ordinal and non-extern 174 // relocation entries. 175 176 // Darwin 'as' doesn't emit correct relocations for this (it ends up with a 177 // single SIGNED relocation); reject it for now. Except the case where both 178 // symbols don't have a base, equal but both NULL. 179 if (A_Base == B_Base && A_Base) 180 report_fatal_error("unsupported relocation with identical base", false); 181 182 // A subtraction expression where both symbols are undefined is a 183 // non-relocatable expression. 184 if (A->isUndefined() && B->isUndefined()) 185 report_fatal_error("unsupported relocation with subtraction expression", 186 false); 187 188 Value += Writer->getSymbolAddress(&A_SD, Layout) - 189 (!A_Base ? 0 : Writer->getSymbolAddress(A_Base, Layout)); 190 Value -= Writer->getSymbolAddress(&B_SD, Layout) - 191 (!B_Base ? 0 : Writer->getSymbolAddress(B_Base, Layout)); 192 193 if (A_Base) { 194 Index = A_Base->getIndex(); 195 IsExtern = 1; 196 } 197 else { 198 Index = A_SD.getFragment()->getParent()->getOrdinal() + 1; 199 IsExtern = 0; 200 } 201 Type = MachO::X86_64_RELOC_UNSIGNED; 202 203 MachO::any_relocation_info MRE; 204 MRE.r_word0 = FixupOffset; 205 MRE.r_word1 = ((Index << 0) | 206 (IsPCRel << 24) | 207 (Log2Size << 25) | 208 (IsExtern << 27) | 209 (Type << 28)); 210 Writer->addRelocation(Fragment->getParent(), MRE); 211 212 if (B_Base) { 213 Index = B_Base->getIndex(); 214 IsExtern = 1; 215 } 216 else { 217 Index = B_SD.getFragment()->getParent()->getOrdinal() + 1; 218 IsExtern = 0; 219 } 220 Type = MachO::X86_64_RELOC_SUBTRACTOR; 221 } else { 222 const MCSymbol *Symbol = &Target.getSymA()->getSymbol(); 223 const MCSymbolData &SD = Asm.getSymbolData(*Symbol); 224 const MCSymbolData *Base = Asm.getAtom(&SD); 225 226 // Relocations inside debug sections always use local relocations when 227 // possible. This seems to be done because the debugger doesn't fully 228 // understand x86_64 relocation entries, and expects to find values that 229 // have already been fixed up. 230 if (Symbol->isInSection()) { 231 const MCSectionMachO &Section = static_cast<const MCSectionMachO&>( 232 Fragment->getParent()->getSection()); 233 if (Section.hasAttribute(MachO::S_ATTR_DEBUG)) 234 Base = nullptr; 235 } 236 237 // x86_64 almost always uses external relocations, except when there is no 238 // symbol to use as a base address (a local symbol with no preceding 239 // non-local symbol). 240 if (Base) { 241 Index = Base->getIndex(); 242 IsExtern = 1; 243 244 // Add the local offset, if needed. 245 if (Base != &SD) 246 Value += Layout.getSymbolOffset(&SD) - Layout.getSymbolOffset(Base); 247 } else if (Symbol->isInSection() && !Symbol->isVariable()) { 248 // The index is the section ordinal (1-based). 249 Index = SD.getFragment()->getParent()->getOrdinal() + 1; 250 IsExtern = 0; 251 Value += Writer->getSymbolAddress(&SD, Layout); 252 253 if (IsPCRel) 254 Value -= FixupAddress + (1 << Log2Size); 255 } else if (Symbol->isVariable()) { 256 const MCExpr *Value = Symbol->getVariableValue(); 257 int64_t Res; 258 bool isAbs = Value->EvaluateAsAbsolute(Res, Layout, 259 Writer->getSectionAddressMap()); 260 if (isAbs) { 261 FixedValue = Res; 262 return; 263 } else { 264 report_fatal_error("unsupported relocation of variable '" + 265 Symbol->getName() + "'", false); 266 } 267 } else { 268 report_fatal_error("unsupported relocation of undefined symbol '" + 269 Symbol->getName() + "'", false); 270 } 271 272 MCSymbolRefExpr::VariantKind Modifier = Target.getSymA()->getKind(); 273 if (IsPCRel) { 274 if (IsRIPRel) { 275 if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) { 276 // x86_64 distinguishes movq foo@GOTPCREL so that the linker can 277 // rewrite the movq to an leaq at link time if the symbol ends up in 278 // the same linkage unit. 279 if (unsigned(Fixup.getKind()) == X86::reloc_riprel_4byte_movq_load) 280 Type = MachO::X86_64_RELOC_GOT_LOAD; 281 else 282 Type = MachO::X86_64_RELOC_GOT; 283 } else if (Modifier == MCSymbolRefExpr::VK_TLVP) { 284 Type = MachO::X86_64_RELOC_TLV; 285 } else if (Modifier != MCSymbolRefExpr::VK_None) { 286 report_fatal_error("unsupported symbol modifier in relocation", 287 false); 288 } else { 289 Type = MachO::X86_64_RELOC_SIGNED; 290 291 // The Darwin x86_64 relocation format has a problem where it cannot 292 // encode an address (L<foo> + <constant>) which is outside the atom 293 // containing L<foo>. Generally, this shouldn't occur but it does 294 // happen when we have a RIPrel instruction with data following the 295 // relocation entry (e.g., movb $012, L0(%rip)). Even with the PCrel 296 // adjustment Darwin x86_64 uses, the offset is still negative and the 297 // linker has no way to recognize this. 298 // 299 // To work around this, Darwin uses several special relocation types 300 // to indicate the offsets. However, the specification or 301 // implementation of these seems to also be incomplete; they should 302 // adjust the addend as well based on the actual encoded instruction 303 // (the additional bias), but instead appear to just look at the final 304 // offset. 305 switch (-(Target.getConstant() + (1LL << Log2Size))) { 306 case 1: Type = MachO::X86_64_RELOC_SIGNED_1; break; 307 case 2: Type = MachO::X86_64_RELOC_SIGNED_2; break; 308 case 4: Type = MachO::X86_64_RELOC_SIGNED_4; break; 309 } 310 } 311 } else { 312 if (Modifier != MCSymbolRefExpr::VK_None) 313 report_fatal_error("unsupported symbol modifier in branch " 314 "relocation", false); 315 316 Type = MachO::X86_64_RELOC_BRANCH; 317 } 318 } else { 319 if (Modifier == MCSymbolRefExpr::VK_GOT) { 320 Type = MachO::X86_64_RELOC_GOT; 321 } else if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) { 322 // GOTPCREL is allowed as a modifier on non-PCrel instructions, in which 323 // case all we do is set the PCrel bit in the relocation entry; this is 324 // used with exception handling, for example. The source is required to 325 // include any necessary offset directly. 326 Type = MachO::X86_64_RELOC_GOT; 327 IsPCRel = 1; 328 } else if (Modifier == MCSymbolRefExpr::VK_TLVP) { 329 report_fatal_error("TLVP symbol modifier should have been rip-rel", 330 false); 331 } else if (Modifier != MCSymbolRefExpr::VK_None) 332 report_fatal_error("unsupported symbol modifier in relocation", false); 333 else { 334 Type = MachO::X86_64_RELOC_UNSIGNED; 335 unsigned Kind = Fixup.getKind(); 336 if (Kind == X86::reloc_signed_4byte) 337 report_fatal_error("32-bit absolute addressing is not supported in " 338 "64-bit mode", false); 339 } 340 } 341 } 342 343 // x86_64 always writes custom values into the fixups. 344 FixedValue = Value; 345 346 // struct relocation_info (8 bytes) 347 MachO::any_relocation_info MRE; 348 MRE.r_word0 = FixupOffset; 349 MRE.r_word1 = ((Index << 0) | 350 (IsPCRel << 24) | 351 (Log2Size << 25) | 352 (IsExtern << 27) | 353 (Type << 28)); 354 Writer->addRelocation(Fragment->getParent(), MRE); 355 } 356 357 bool X86MachObjectWriter::RecordScatteredRelocation(MachObjectWriter *Writer, 358 const MCAssembler &Asm, 359 const MCAsmLayout &Layout, 360 const MCFragment *Fragment, 361 const MCFixup &Fixup, 362 MCValue Target, 363 unsigned Log2Size, 364 uint64_t &FixedValue) { 365 uint64_t OriginalFixedValue = FixedValue; 366 uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset(); 367 unsigned IsPCRel = Writer->isFixupKindPCRel(Asm, Fixup.getKind()); 368 unsigned Type = MachO::GENERIC_RELOC_VANILLA; 369 370 // See <reloc.h>. 371 const MCSymbol *A = &Target.getSymA()->getSymbol(); 372 const MCSymbolData *A_SD = &Asm.getSymbolData(*A); 373 374 if (!A_SD->getFragment()) 375 report_fatal_error("symbol '" + A->getName() + 376 "' can not be undefined in a subtraction expression", 377 false); 378 379 uint32_t Value = Writer->getSymbolAddress(A_SD, Layout); 380 uint64_t SecAddr = Writer->getSectionAddress(A_SD->getFragment()->getParent()); 381 FixedValue += SecAddr; 382 uint32_t Value2 = 0; 383 384 if (const MCSymbolRefExpr *B = Target.getSymB()) { 385 const MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol()); 386 387 if (!B_SD->getFragment()) 388 report_fatal_error("symbol '" + B->getSymbol().getName() + 389 "' can not be undefined in a subtraction expression", 390 false); 391 392 // Select the appropriate difference relocation type. 393 // 394 // Note that there is no longer any semantic difference between these two 395 // relocation types from the linkers point of view, this is done solely for 396 // pedantic compatibility with 'as'. 397 Type = A_SD->isExternal() ? (unsigned)MachO::GENERIC_RELOC_SECTDIFF : 398 (unsigned)MachO::GENERIC_RELOC_LOCAL_SECTDIFF; 399 Value2 = Writer->getSymbolAddress(B_SD, Layout); 400 FixedValue -= Writer->getSectionAddress(B_SD->getFragment()->getParent()); 401 } 402 403 // Relocations are written out in reverse order, so the PAIR comes first. 404 if (Type == MachO::GENERIC_RELOC_SECTDIFF || 405 Type == MachO::GENERIC_RELOC_LOCAL_SECTDIFF) { 406 // If the offset is too large to fit in a scattered relocation, 407 // we're hosed. It's an unfortunate limitation of the MachO format. 408 if (FixupOffset > 0xffffff) { 409 char Buffer[32]; 410 format("0x%x", FixupOffset).print(Buffer, sizeof(Buffer)); 411 Asm.getContext().FatalError(Fixup.getLoc(), 412 Twine("Section too large, can't encode " 413 "r_address (") + Buffer + 414 ") into 24 bits of scattered " 415 "relocation entry."); 416 llvm_unreachable("fatal error returned?!"); 417 } 418 419 MachO::any_relocation_info MRE; 420 MRE.r_word0 = ((0 << 0) | // r_address 421 (MachO::GENERIC_RELOC_PAIR << 24) | // r_type 422 (Log2Size << 28) | 423 (IsPCRel << 30) | 424 MachO::R_SCATTERED); 425 MRE.r_word1 = Value2; 426 Writer->addRelocation(Fragment->getParent(), MRE); 427 } else { 428 // If the offset is more than 24-bits, it won't fit in a scattered 429 // relocation offset field, so we fall back to using a non-scattered 430 // relocation. This is a bit risky, as if the offset reaches out of 431 // the block and the linker is doing scattered loading on this 432 // symbol, things can go badly. 433 // 434 // Required for 'as' compatibility. 435 if (FixupOffset > 0xffffff) { 436 FixedValue = OriginalFixedValue; 437 return false; 438 } 439 } 440 441 MachO::any_relocation_info MRE; 442 MRE.r_word0 = ((FixupOffset << 0) | 443 (Type << 24) | 444 (Log2Size << 28) | 445 (IsPCRel << 30) | 446 MachO::R_SCATTERED); 447 MRE.r_word1 = Value; 448 Writer->addRelocation(Fragment->getParent(), MRE); 449 return true; 450 } 451 452 void X86MachObjectWriter::RecordTLVPRelocation(MachObjectWriter *Writer, 453 const MCAssembler &Asm, 454 const MCAsmLayout &Layout, 455 const MCFragment *Fragment, 456 const MCFixup &Fixup, 457 MCValue Target, 458 uint64_t &FixedValue) { 459 assert(Target.getSymA()->getKind() == MCSymbolRefExpr::VK_TLVP && 460 !is64Bit() && 461 "Should only be called with a 32-bit TLVP relocation!"); 462 463 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind()); 464 uint32_t Value = Layout.getFragmentOffset(Fragment)+Fixup.getOffset(); 465 unsigned IsPCRel = 0; 466 467 // Get the symbol data. 468 const MCSymbolData *SD_A = &Asm.getSymbolData(Target.getSymA()->getSymbol()); 469 unsigned Index = SD_A->getIndex(); 470 471 // We're only going to have a second symbol in pic mode and it'll be a 472 // subtraction from the picbase. For 32-bit pic the addend is the difference 473 // between the picbase and the next address. For 32-bit static the addend is 474 // zero. 475 if (Target.getSymB()) { 476 // If this is a subtraction then we're pcrel. 477 uint32_t FixupAddress = 478 Writer->getFragmentAddress(Fragment, Layout) + Fixup.getOffset(); 479 const MCSymbolData *SD_B = 480 &Asm.getSymbolData(Target.getSymB()->getSymbol()); 481 IsPCRel = 1; 482 FixedValue = (FixupAddress - Writer->getSymbolAddress(SD_B, Layout) + 483 Target.getConstant()); 484 FixedValue += 1ULL << Log2Size; 485 } else { 486 FixedValue = 0; 487 } 488 489 // struct relocation_info (8 bytes) 490 MachO::any_relocation_info MRE; 491 MRE.r_word0 = Value; 492 MRE.r_word1 = ((Index << 0) | 493 (IsPCRel << 24) | 494 (Log2Size << 25) | 495 (1 << 27) | // r_extern 496 (MachO::GENERIC_RELOC_TLV << 28)); // r_type 497 Writer->addRelocation(Fragment->getParent(), MRE); 498 } 499 500 void X86MachObjectWriter::RecordX86Relocation(MachObjectWriter *Writer, 501 const MCAssembler &Asm, 502 const MCAsmLayout &Layout, 503 const MCFragment *Fragment, 504 const MCFixup &Fixup, 505 MCValue Target, 506 uint64_t &FixedValue) { 507 unsigned IsPCRel = Writer->isFixupKindPCRel(Asm, Fixup.getKind()); 508 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind()); 509 510 // If this is a 32-bit TLVP reloc it's handled a bit differently. 511 if (Target.getSymA() && 512 Target.getSymA()->getKind() == MCSymbolRefExpr::VK_TLVP) { 513 RecordTLVPRelocation(Writer, Asm, Layout, Fragment, Fixup, Target, 514 FixedValue); 515 return; 516 } 517 518 // If this is a difference or a defined symbol plus an offset, then we need a 519 // scattered relocation entry. Differences always require scattered 520 // relocations. 521 if (Target.getSymB()) { 522 RecordScatteredRelocation(Writer, Asm, Layout, Fragment, Fixup, 523 Target, Log2Size, FixedValue); 524 return; 525 } 526 527 // Get the symbol data, if any. 528 const MCSymbolData *SD = nullptr; 529 if (Target.getSymA()) 530 SD = &Asm.getSymbolData(Target.getSymA()->getSymbol()); 531 532 // If this is an internal relocation with an offset, it also needs a scattered 533 // relocation entry. 534 uint32_t Offset = Target.getConstant(); 535 if (IsPCRel) 536 Offset += 1 << Log2Size; 537 // Try to record the scattered relocation if needed. Fall back to non 538 // scattered if necessary (see comments in RecordScatteredRelocation() 539 // for details). 540 if (Offset && SD && !Writer->doesSymbolRequireExternRelocation(SD) && 541 RecordScatteredRelocation(Writer, Asm, Layout, Fragment, Fixup, 542 Target, Log2Size, FixedValue)) 543 return; 544 545 // See <reloc.h>. 546 uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset(); 547 unsigned Index = 0; 548 unsigned IsExtern = 0; 549 unsigned Type = 0; 550 551 if (Target.isAbsolute()) { // constant 552 // SymbolNum of 0 indicates the absolute section. 553 // 554 // FIXME: Currently, these are never generated (see code below). I cannot 555 // find a case where they are actually emitted. 556 Type = MachO::GENERIC_RELOC_VANILLA; 557 } else { 558 // Resolve constant variables. 559 if (SD->getSymbol().isVariable()) { 560 int64_t Res; 561 if (SD->getSymbol().getVariableValue()->EvaluateAsAbsolute( 562 Res, Layout, Writer->getSectionAddressMap())) { 563 FixedValue = Res; 564 return; 565 } 566 } 567 568 // Check whether we need an external or internal relocation. 569 if (Writer->doesSymbolRequireExternRelocation(SD)) { 570 IsExtern = 1; 571 Index = SD->getIndex(); 572 // For external relocations, make sure to offset the fixup value to 573 // compensate for the addend of the symbol address, if it was 574 // undefined. This occurs with weak definitions, for example. 575 if (!SD->Symbol->isUndefined()) 576 FixedValue -= Layout.getSymbolOffset(SD); 577 } else { 578 // The index is the section ordinal (1-based). 579 const MCSectionData &SymSD = Asm.getSectionData( 580 SD->getSymbol().getSection()); 581 Index = SymSD.getOrdinal() + 1; 582 FixedValue += Writer->getSectionAddress(&SymSD); 583 } 584 if (IsPCRel) 585 FixedValue -= Writer->getSectionAddress(Fragment->getParent()); 586 587 Type = MachO::GENERIC_RELOC_VANILLA; 588 } 589 590 // struct relocation_info (8 bytes) 591 MachO::any_relocation_info MRE; 592 MRE.r_word0 = FixupOffset; 593 MRE.r_word1 = ((Index << 0) | 594 (IsPCRel << 24) | 595 (Log2Size << 25) | 596 (IsExtern << 27) | 597 (Type << 28)); 598 Writer->addRelocation(Fragment->getParent(), MRE); 599 } 600 601 MCObjectWriter *llvm::createX86MachObjectWriter(raw_ostream &OS, 602 bool Is64Bit, 603 uint32_t CPUType, 604 uint32_t CPUSubtype) { 605 return createMachObjectWriter(new X86MachObjectWriter(Is64Bit, 606 CPUType, 607 CPUSubtype), 608 OS, /*IsLittleEndian=*/true); 609 } 610
