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/X86FixupKinds.h" 11#include "MCTargetDesc/X86MCTargetDesc.h" 12#include "llvm/MC/MCAssembler.h" 13#include "llvm/MC/MCAsmLayout.h" 14#include "llvm/MC/MCContext.h" 15#include "llvm/MC/MCMachObjectWriter.h" 16#include "llvm/MC/MCSectionMachO.h" 17#include "llvm/MC/MCValue.h" 18#include "llvm/ADT/Twine.h" 19#include "llvm/Support/ErrorHandling.h" 20#include "llvm/Support/Format.h" 21#include "llvm/Object/MachOFormat.h" 22 23using namespace llvm; 24using namespace llvm::object; 25 26namespace { 27class X86MachObjectWriter : public MCMachObjectTargetWriter { 28 bool RecordScatteredRelocation(MachObjectWriter *Writer, 29 const MCAssembler &Asm, 30 const MCAsmLayout &Layout, 31 const MCFragment *Fragment, 32 const MCFixup &Fixup, 33 MCValue Target, 34 unsigned Log2Size, 35 uint64_t &FixedValue); 36 void RecordTLVPRelocation(MachObjectWriter *Writer, 37 const MCAssembler &Asm, 38 const MCAsmLayout &Layout, 39 const MCFragment *Fragment, 40 const MCFixup &Fixup, 41 MCValue Target, 42 uint64_t &FixedValue); 43 44 void RecordX86Relocation(MachObjectWriter *Writer, 45 const MCAssembler &Asm, 46 const MCAsmLayout &Layout, 47 const MCFragment *Fragment, 48 const MCFixup &Fixup, 49 MCValue Target, 50 uint64_t &FixedValue); 51 void RecordX86_64Relocation(MachObjectWriter *Writer, 52 const MCAssembler &Asm, 53 const MCAsmLayout &Layout, 54 const MCFragment *Fragment, 55 const MCFixup &Fixup, 56 MCValue Target, 57 uint64_t &FixedValue); 58public: 59 X86MachObjectWriter(bool Is64Bit, uint32_t CPUType, 60 uint32_t CPUSubtype) 61 : MCMachObjectTargetWriter(Is64Bit, CPUType, CPUSubtype, 62 /*UseAggressiveSymbolFolding=*/Is64Bit) {} 63 64 void RecordRelocation(MachObjectWriter *Writer, 65 const MCAssembler &Asm, const MCAsmLayout &Layout, 66 const MCFragment *Fragment, const MCFixup &Fixup, 67 MCValue Target, uint64_t &FixedValue) { 68 if (Writer->is64Bit()) 69 RecordX86_64Relocation(Writer, Asm, Layout, Fragment, Fixup, Target, 70 FixedValue); 71 else 72 RecordX86Relocation(Writer, Asm, Layout, Fragment, Fixup, Target, 73 FixedValue); 74 } 75}; 76} 77 78static bool isFixupKindRIPRel(unsigned Kind) { 79 return Kind == X86::reloc_riprel_4byte || 80 Kind == X86::reloc_riprel_4byte_movq_load; 81} 82 83static unsigned getFixupKindLog2Size(unsigned Kind) { 84 switch (Kind) { 85 default: 86 llvm_unreachable("invalid fixup kind!"); 87 case FK_PCRel_1: 88 case FK_Data_1: return 0; 89 case FK_PCRel_2: 90 case FK_Data_2: return 1; 91 case FK_PCRel_4: 92 // FIXME: Remove these!!! 93 case X86::reloc_riprel_4byte: 94 case X86::reloc_riprel_4byte_movq_load: 95 case X86::reloc_signed_4byte: 96 case FK_Data_4: return 2; 97 case FK_Data_8: return 3; 98 } 99} 100 101void X86MachObjectWriter::RecordX86_64Relocation(MachObjectWriter *Writer, 102 const MCAssembler &Asm, 103 const MCAsmLayout &Layout, 104 const MCFragment *Fragment, 105 const MCFixup &Fixup, 106 MCValue Target, 107 uint64_t &FixedValue) { 108 unsigned IsPCRel = Writer->isFixupKindPCRel(Asm, Fixup.getKind()); 109 unsigned IsRIPRel = isFixupKindRIPRel(Fixup.getKind()); 110 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind()); 111 112 // See <reloc.h>. 113 uint32_t FixupOffset = 114 Layout.getFragmentOffset(Fragment) + Fixup.getOffset(); 115 uint32_t FixupAddress = 116 Writer->getFragmentAddress(Fragment, Layout) + Fixup.getOffset(); 117 int64_t Value = 0; 118 unsigned Index = 0; 119 unsigned IsExtern = 0; 120 unsigned Type = 0; 121 122 Value = Target.getConstant(); 123 124 if (IsPCRel) { 125 // Compensate for the relocation offset, Darwin x86_64 relocations only have 126 // the addend and appear to have attempted to define it to be the actual 127 // expression addend without the PCrel bias. However, instructions with data 128 // following the relocation are not accommodated for (see comment below 129 // regarding SIGNED{1,2,4}), so it isn't exactly that either. 130 Value += 1LL << Log2Size; 131 } 132 133 if (Target.isAbsolute()) { // constant 134 // SymbolNum of 0 indicates the absolute section. 135 Type = macho::RIT_X86_64_Unsigned; 136 Index = 0; 137 138 // FIXME: I believe this is broken, I don't think the linker can understand 139 // it. I think it would require a local relocation, but I'm not sure if that 140 // would work either. The official way to get an absolute PCrel relocation 141 // is to use an absolute symbol (which we don't support yet). 142 if (IsPCRel) { 143 IsExtern = 1; 144 Type = macho::RIT_X86_64_Branch; 145 } 146 } else if (Target.getSymB()) { // A - B + constant 147 const MCSymbol *A = &Target.getSymA()->getSymbol(); 148 MCSymbolData &A_SD = Asm.getSymbolData(*A); 149 const MCSymbolData *A_Base = Asm.getAtom(&A_SD); 150 151 const MCSymbol *B = &Target.getSymB()->getSymbol(); 152 MCSymbolData &B_SD = Asm.getSymbolData(*B); 153 const MCSymbolData *B_Base = Asm.getAtom(&B_SD); 154 155 // Neither symbol can be modified. 156 if (Target.getSymA()->getKind() != MCSymbolRefExpr::VK_None || 157 Target.getSymB()->getKind() != MCSymbolRefExpr::VK_None) 158 report_fatal_error("unsupported relocation of modified symbol"); 159 160 // We don't support PCrel relocations of differences. Darwin 'as' doesn't 161 // implement most of these correctly. 162 if (IsPCRel) 163 report_fatal_error("unsupported pc-relative relocation of difference"); 164 165 // The support for the situation where one or both of the symbols would 166 // require a local relocation is handled just like if the symbols were 167 // external. This is certainly used in the case of debug sections where the 168 // section has only temporary symbols and thus the symbols don't have base 169 // symbols. This is encoded using the section ordinal and non-extern 170 // relocation entries. 171 172 // Darwin 'as' doesn't emit correct relocations for this (it ends up with a 173 // single SIGNED relocation); reject it for now. Except the case where both 174 // symbols don't have a base, equal but both NULL. 175 if (A_Base == B_Base && A_Base) 176 report_fatal_error("unsupported relocation with identical base"); 177 178 Value += Writer->getSymbolAddress(&A_SD, Layout) - 179 (A_Base == NULL ? 0 : Writer->getSymbolAddress(A_Base, Layout)); 180 Value -= Writer->getSymbolAddress(&B_SD, Layout) - 181 (B_Base == NULL ? 0 : Writer->getSymbolAddress(B_Base, Layout)); 182 183 if (A_Base) { 184 Index = A_Base->getIndex(); 185 IsExtern = 1; 186 } 187 else { 188 Index = A_SD.getFragment()->getParent()->getOrdinal() + 1; 189 IsExtern = 0; 190 } 191 Type = macho::RIT_X86_64_Unsigned; 192 193 macho::RelocationEntry MRE; 194 MRE.Word0 = FixupOffset; 195 MRE.Word1 = ((Index << 0) | 196 (IsPCRel << 24) | 197 (Log2Size << 25) | 198 (IsExtern << 27) | 199 (Type << 28)); 200 Writer->addRelocation(Fragment->getParent(), MRE); 201 202 if (B_Base) { 203 Index = B_Base->getIndex(); 204 IsExtern = 1; 205 } 206 else { 207 Index = B_SD.getFragment()->getParent()->getOrdinal() + 1; 208 IsExtern = 0; 209 } 210 Type = macho::RIT_X86_64_Subtractor; 211 } else { 212 const MCSymbol *Symbol = &Target.getSymA()->getSymbol(); 213 MCSymbolData &SD = Asm.getSymbolData(*Symbol); 214 const MCSymbolData *Base = Asm.getAtom(&SD); 215 216 // Relocations inside debug sections always use local relocations when 217 // possible. This seems to be done because the debugger doesn't fully 218 // understand x86_64 relocation entries, and expects to find values that 219 // have already been fixed up. 220 if (Symbol->isInSection()) { 221 const MCSectionMachO &Section = static_cast<const MCSectionMachO&>( 222 Fragment->getParent()->getSection()); 223 if (Section.hasAttribute(MCSectionMachO::S_ATTR_DEBUG)) 224 Base = 0; 225 } 226 227 // x86_64 almost always uses external relocations, except when there is no 228 // symbol to use as a base address (a local symbol with no preceding 229 // non-local symbol). 230 if (Base) { 231 Index = Base->getIndex(); 232 IsExtern = 1; 233 234 // Add the local offset, if needed. 235 if (Base != &SD) 236 Value += Layout.getSymbolOffset(&SD) - Layout.getSymbolOffset(Base); 237 } else if (Symbol->isInSection() && !Symbol->isVariable()) { 238 // The index is the section ordinal (1-based). 239 Index = SD.getFragment()->getParent()->getOrdinal() + 1; 240 IsExtern = 0; 241 Value += Writer->getSymbolAddress(&SD, Layout); 242 243 if (IsPCRel) 244 Value -= FixupAddress + (1 << Log2Size); 245 } else if (Symbol->isVariable()) { 246 const MCExpr *Value = Symbol->getVariableValue(); 247 int64_t Res; 248 bool isAbs = Value->EvaluateAsAbsolute(Res, Layout, 249 Writer->getSectionAddressMap()); 250 if (isAbs) { 251 FixedValue = Res; 252 return; 253 } else { 254 report_fatal_error("unsupported relocation of variable '" + 255 Symbol->getName() + "'"); 256 } 257 } else { 258 report_fatal_error("unsupported relocation of undefined symbol '" + 259 Symbol->getName() + "'"); 260 } 261 262 MCSymbolRefExpr::VariantKind Modifier = Target.getSymA()->getKind(); 263 if (IsPCRel) { 264 if (IsRIPRel) { 265 if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) { 266 // x86_64 distinguishes movq foo@GOTPCREL so that the linker can 267 // rewrite the movq to an leaq at link time if the symbol ends up in 268 // the same linkage unit. 269 if (unsigned(Fixup.getKind()) == X86::reloc_riprel_4byte_movq_load) 270 Type = macho::RIT_X86_64_GOTLoad; 271 else 272 Type = macho::RIT_X86_64_GOT; 273 } else if (Modifier == MCSymbolRefExpr::VK_TLVP) { 274 Type = macho::RIT_X86_64_TLV; 275 } else if (Modifier != MCSymbolRefExpr::VK_None) { 276 report_fatal_error("unsupported symbol modifier in relocation"); 277 } else { 278 Type = macho::RIT_X86_64_Signed; 279 280 // The Darwin x86_64 relocation format has a problem where it cannot 281 // encode an address (L<foo> + <constant>) which is outside the atom 282 // containing L<foo>. Generally, this shouldn't occur but it does 283 // happen when we have a RIPrel instruction with data following the 284 // relocation entry (e.g., movb $012, L0(%rip)). Even with the PCrel 285 // adjustment Darwin x86_64 uses, the offset is still negative and the 286 // linker has no way to recognize this. 287 // 288 // To work around this, Darwin uses several special relocation types 289 // to indicate the offsets. However, the specification or 290 // implementation of these seems to also be incomplete; they should 291 // adjust the addend as well based on the actual encoded instruction 292 // (the additional bias), but instead appear to just look at the final 293 // offset. 294 switch (-(Target.getConstant() + (1LL << Log2Size))) { 295 case 1: Type = macho::RIT_X86_64_Signed1; break; 296 case 2: Type = macho::RIT_X86_64_Signed2; break; 297 case 4: Type = macho::RIT_X86_64_Signed4; break; 298 } 299 } 300 } else { 301 if (Modifier != MCSymbolRefExpr::VK_None) 302 report_fatal_error("unsupported symbol modifier in branch " 303 "relocation"); 304 305 Type = macho::RIT_X86_64_Branch; 306 } 307 } else { 308 if (Modifier == MCSymbolRefExpr::VK_GOT) { 309 Type = macho::RIT_X86_64_GOT; 310 } else if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) { 311 // GOTPCREL is allowed as a modifier on non-PCrel instructions, in which 312 // case all we do is set the PCrel bit in the relocation entry; this is 313 // used with exception handling, for example. The source is required to 314 // include any necessary offset directly. 315 Type = macho::RIT_X86_64_GOT; 316 IsPCRel = 1; 317 } else if (Modifier == MCSymbolRefExpr::VK_TLVP) { 318 report_fatal_error("TLVP symbol modifier should have been rip-rel"); 319 } else if (Modifier != MCSymbolRefExpr::VK_None) 320 report_fatal_error("unsupported symbol modifier in relocation"); 321 else 322 Type = macho::RIT_X86_64_Unsigned; 323 } 324 } 325 326 // x86_64 always writes custom values into the fixups. 327 FixedValue = Value; 328 329 // struct relocation_info (8 bytes) 330 macho::RelocationEntry MRE; 331 MRE.Word0 = FixupOffset; 332 MRE.Word1 = ((Index << 0) | 333 (IsPCRel << 24) | 334 (Log2Size << 25) | 335 (IsExtern << 27) | 336 (Type << 28)); 337 Writer->addRelocation(Fragment->getParent(), MRE); 338} 339 340bool X86MachObjectWriter::RecordScatteredRelocation(MachObjectWriter *Writer, 341 const MCAssembler &Asm, 342 const MCAsmLayout &Layout, 343 const MCFragment *Fragment, 344 const MCFixup &Fixup, 345 MCValue Target, 346 unsigned Log2Size, 347 uint64_t &FixedValue) { 348 uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset(); 349 unsigned IsPCRel = Writer->isFixupKindPCRel(Asm, Fixup.getKind()); 350 unsigned Type = macho::RIT_Vanilla; 351 352 // See <reloc.h>. 353 const MCSymbol *A = &Target.getSymA()->getSymbol(); 354 MCSymbolData *A_SD = &Asm.getSymbolData(*A); 355 356 if (!A_SD->getFragment()) 357 report_fatal_error("symbol '" + A->getName() + 358 "' can not be undefined in a subtraction expression"); 359 360 uint32_t Value = Writer->getSymbolAddress(A_SD, Layout); 361 uint64_t SecAddr = Writer->getSectionAddress(A_SD->getFragment()->getParent()); 362 FixedValue += SecAddr; 363 uint32_t Value2 = 0; 364 365 if (const MCSymbolRefExpr *B = Target.getSymB()) { 366 MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol()); 367 368 if (!B_SD->getFragment()) 369 report_fatal_error("symbol '" + B->getSymbol().getName() + 370 "' can not be undefined in a subtraction expression"); 371 372 // Select the appropriate difference relocation type. 373 // 374 // Note that there is no longer any semantic difference between these two 375 // relocation types from the linkers point of view, this is done solely for 376 // pedantic compatibility with 'as'. 377 Type = A_SD->isExternal() ? (unsigned)macho::RIT_Difference : 378 (unsigned)macho::RIT_Generic_LocalDifference; 379 Value2 = Writer->getSymbolAddress(B_SD, Layout); 380 FixedValue -= Writer->getSectionAddress(B_SD->getFragment()->getParent()); 381 } 382 383 // Relocations are written out in reverse order, so the PAIR comes first. 384 if (Type == macho::RIT_Difference || 385 Type == macho::RIT_Generic_LocalDifference) { 386 // If the offset is too large to fit in a scattered relocation, 387 // we're hosed. It's an unfortunate limitation of the MachO format. 388 if (FixupOffset > 0xffffff) { 389 char Buffer[32]; 390 format("0x%x", FixupOffset).print(Buffer, sizeof(Buffer)); 391 Asm.getContext().FatalError(Fixup.getLoc(), 392 Twine("Section too large, can't encode " 393 "r_address (") + Buffer + 394 ") into 24 bits of scattered " 395 "relocation entry."); 396 llvm_unreachable("fatal error returned?!"); 397 } 398 399 macho::RelocationEntry MRE; 400 MRE.Word0 = ((0 << 0) | 401 (macho::RIT_Pair << 24) | 402 (Log2Size << 28) | 403 (IsPCRel << 30) | 404 macho::RF_Scattered); 405 MRE.Word1 = Value2; 406 Writer->addRelocation(Fragment->getParent(), MRE); 407 } else { 408 // If the offset is more than 24-bits, it won't fit in a scattered 409 // relocation offset field, so we fall back to using a non-scattered 410 // relocation. This is a bit risky, as if the offset reaches out of 411 // the block and the linker is doing scattered loading on this 412 // symbol, things can go badly. 413 // 414 // Required for 'as' compatibility. 415 if (FixupOffset > 0xffffff) 416 return false; 417 } 418 419 macho::RelocationEntry MRE; 420 MRE.Word0 = ((FixupOffset << 0) | 421 (Type << 24) | 422 (Log2Size << 28) | 423 (IsPCRel << 30) | 424 macho::RF_Scattered); 425 MRE.Word1 = Value; 426 Writer->addRelocation(Fragment->getParent(), MRE); 427 return true; 428} 429 430void X86MachObjectWriter::RecordTLVPRelocation(MachObjectWriter *Writer, 431 const MCAssembler &Asm, 432 const MCAsmLayout &Layout, 433 const MCFragment *Fragment, 434 const MCFixup &Fixup, 435 MCValue Target, 436 uint64_t &FixedValue) { 437 assert(Target.getSymA()->getKind() == MCSymbolRefExpr::VK_TLVP && 438 !is64Bit() && 439 "Should only be called with a 32-bit TLVP relocation!"); 440 441 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind()); 442 uint32_t Value = Layout.getFragmentOffset(Fragment)+Fixup.getOffset(); 443 unsigned IsPCRel = 0; 444 445 // Get the symbol data. 446 MCSymbolData *SD_A = &Asm.getSymbolData(Target.getSymA()->getSymbol()); 447 unsigned Index = SD_A->getIndex(); 448 449 // We're only going to have a second symbol in pic mode and it'll be a 450 // subtraction from the picbase. For 32-bit pic the addend is the difference 451 // between the picbase and the next address. For 32-bit static the addend is 452 // zero. 453 if (Target.getSymB()) { 454 // If this is a subtraction then we're pcrel. 455 uint32_t FixupAddress = 456 Writer->getFragmentAddress(Fragment, Layout) + Fixup.getOffset(); 457 MCSymbolData *SD_B = &Asm.getSymbolData(Target.getSymB()->getSymbol()); 458 IsPCRel = 1; 459 FixedValue = (FixupAddress - Writer->getSymbolAddress(SD_B, Layout) + 460 Target.getConstant()); 461 FixedValue += 1ULL << Log2Size; 462 } else { 463 FixedValue = 0; 464 } 465 466 // struct relocation_info (8 bytes) 467 macho::RelocationEntry MRE; 468 MRE.Word0 = Value; 469 MRE.Word1 = ((Index << 0) | 470 (IsPCRel << 24) | 471 (Log2Size << 25) | 472 (1 << 27) | // Extern 473 (macho::RIT_Generic_TLV << 28)); // Type 474 Writer->addRelocation(Fragment->getParent(), MRE); 475} 476 477void X86MachObjectWriter::RecordX86Relocation(MachObjectWriter *Writer, 478 const MCAssembler &Asm, 479 const MCAsmLayout &Layout, 480 const MCFragment *Fragment, 481 const MCFixup &Fixup, 482 MCValue Target, 483 uint64_t &FixedValue) { 484 unsigned IsPCRel = Writer->isFixupKindPCRel(Asm, Fixup.getKind()); 485 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind()); 486 487 // If this is a 32-bit TLVP reloc it's handled a bit differently. 488 if (Target.getSymA() && 489 Target.getSymA()->getKind() == MCSymbolRefExpr::VK_TLVP) { 490 RecordTLVPRelocation(Writer, Asm, Layout, Fragment, Fixup, Target, 491 FixedValue); 492 return; 493 } 494 495 // If this is a difference or a defined symbol plus an offset, then we need a 496 // scattered relocation entry. Differences always require scattered 497 // relocations. 498 if (Target.getSymB()) { 499 RecordScatteredRelocation(Writer, Asm, Layout, Fragment, Fixup, 500 Target, Log2Size, FixedValue); 501 return; 502 } 503 504 // Get the symbol data, if any. 505 MCSymbolData *SD = 0; 506 if (Target.getSymA()) 507 SD = &Asm.getSymbolData(Target.getSymA()->getSymbol()); 508 509 // If this is an internal relocation with an offset, it also needs a scattered 510 // relocation entry. 511 uint32_t Offset = Target.getConstant(); 512 if (IsPCRel) 513 Offset += 1 << Log2Size; 514 // Try to record the scattered relocation if needed. Fall back to non 515 // scattered if necessary (see comments in RecordScatteredRelocation() 516 // for details). 517 if (Offset && SD && !Writer->doesSymbolRequireExternRelocation(SD) && 518 RecordScatteredRelocation(Writer, Asm, Layout, Fragment, Fixup, 519 Target, Log2Size, FixedValue)) 520 return; 521 522 // See <reloc.h>. 523 uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset(); 524 unsigned Index = 0; 525 unsigned IsExtern = 0; 526 unsigned Type = 0; 527 528 if (Target.isAbsolute()) { // constant 529 // SymbolNum of 0 indicates the absolute section. 530 // 531 // FIXME: Currently, these are never generated (see code below). I cannot 532 // find a case where they are actually emitted. 533 Type = macho::RIT_Vanilla; 534 } else { 535 // Resolve constant variables. 536 if (SD->getSymbol().isVariable()) { 537 int64_t Res; 538 if (SD->getSymbol().getVariableValue()->EvaluateAsAbsolute( 539 Res, Layout, Writer->getSectionAddressMap())) { 540 FixedValue = Res; 541 return; 542 } 543 } 544 545 // Check whether we need an external or internal relocation. 546 if (Writer->doesSymbolRequireExternRelocation(SD)) { 547 IsExtern = 1; 548 Index = SD->getIndex(); 549 // For external relocations, make sure to offset the fixup value to 550 // compensate for the addend of the symbol address, if it was 551 // undefined. This occurs with weak definitions, for example. 552 if (!SD->Symbol->isUndefined()) 553 FixedValue -= Layout.getSymbolOffset(SD); 554 } else { 555 // The index is the section ordinal (1-based). 556 const MCSectionData &SymSD = Asm.getSectionData( 557 SD->getSymbol().getSection()); 558 Index = SymSD.getOrdinal() + 1; 559 FixedValue += Writer->getSectionAddress(&SymSD); 560 } 561 if (IsPCRel) 562 FixedValue -= Writer->getSectionAddress(Fragment->getParent()); 563 564 Type = macho::RIT_Vanilla; 565 } 566 567 // struct relocation_info (8 bytes) 568 macho::RelocationEntry MRE; 569 MRE.Word0 = FixupOffset; 570 MRE.Word1 = ((Index << 0) | 571 (IsPCRel << 24) | 572 (Log2Size << 25) | 573 (IsExtern << 27) | 574 (Type << 28)); 575 Writer->addRelocation(Fragment->getParent(), MRE); 576} 577 578MCObjectWriter *llvm::createX86MachObjectWriter(raw_ostream &OS, 579 bool Is64Bit, 580 uint32_t CPUType, 581 uint32_t CPUSubtype) { 582 return createMachObjectWriter(new X86MachObjectWriter(Is64Bit, 583 CPUType, 584 CPUSubtype), 585 OS, /*IsLittleEndian=*/true); 586} 587