1 //===- lib/MC/MachObjectWriter.cpp - Mach-O File Writer -------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "llvm/MC/MCMachObjectWriter.h"
11 #include "llvm/ADT/OwningPtr.h"
12 #include "llvm/ADT/StringMap.h"
13 #include "llvm/ADT/Twine.h"
14 #include "llvm/MC/MCAssembler.h"
15 #include "llvm/MC/MCAsmLayout.h"
16 #include "llvm/MC/MCExpr.h"
17 #include "llvm/MC/MCObjectWriter.h"
18 #include "llvm/MC/MCSectionMachO.h"
19 #include "llvm/MC/MCSymbol.h"
20 #include "llvm/MC/MCMachOSymbolFlags.h"
21 #include "llvm/MC/MCValue.h"
22 #include "llvm/Object/MachOFormat.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Target/TargetAsmBackend.h"
27 #include "../Target/X86/X86FixupKinds.h"
31 using namespace llvm::object;
33 // FIXME: this has been copied from (or to) X86AsmBackend.cpp
34 static unsigned getFixupKindLog2Size(unsigned Kind) {
36 // FIXME: Until ARM has it's own relocation stuff spun off, it comes
37 // through here and we don't want it to puke all over. Any reasonable
38 // values will only come when ARM relocation support gets added, at which
39 // point this will be X86 only again and the llvm_unreachable can be
41 default: return 0;// llvm_unreachable("invalid fixup kind!");
43 case FK_Data_1: return 0;
45 case FK_Data_2: return 1;
47 case X86::reloc_riprel_4byte:
48 case X86::reloc_riprel_4byte_movq_load:
49 case X86::reloc_signed_4byte:
50 case FK_Data_4: return 2;
51 case FK_Data_8: return 3;
55 static bool doesSymbolRequireExternRelocation(MCSymbolData *SD) {
56 // Undefined symbols are always extern.
57 if (SD->Symbol->isUndefined())
60 // References to weak definitions require external relocation entries; the
61 // definition may not always be the one in the same object file.
62 if (SD->getFlags() & SF_WeakDefinition)
65 // Otherwise, we can use an internal relocation.
69 static bool isScatteredFixupFullyResolved(const MCAssembler &Asm,
71 const MCSymbolData *BaseSymbol) {
72 // The effective fixup address is
73 // addr(atom(A)) + offset(A)
74 // - addr(atom(B)) - offset(B)
75 // - addr(BaseSymbol) + <fixup offset from base symbol>
76 // and the offsets are not relocatable, so the fixup is fully resolved when
77 // addr(atom(A)) - addr(atom(B)) - addr(BaseSymbol) == 0.
79 // Note that "false" is almost always conservatively correct (it means we emit
80 // a relocation which is unnecessary), except when it would force us to emit a
81 // relocation which the target cannot encode.
83 const MCSymbolData *A_Base = 0, *B_Base = 0;
84 if (const MCSymbolRefExpr *A = Target.getSymA()) {
85 // Modified symbol references cannot be resolved.
86 if (A->getKind() != MCSymbolRefExpr::VK_None)
89 A_Base = Asm.getAtom(&Asm.getSymbolData(A->getSymbol()));
94 if (const MCSymbolRefExpr *B = Target.getSymB()) {
95 // Modified symbol references cannot be resolved.
96 if (B->getKind() != MCSymbolRefExpr::VK_None)
99 B_Base = Asm.getAtom(&Asm.getSymbolData(B->getSymbol()));
104 // If there is no base, A and B have to be the same atom for this fixup to be
107 return A_Base == B_Base;
109 // Otherwise, B must be missing and A must be the base.
110 return !B_Base && BaseSymbol == A_Base;
113 static bool isScatteredFixupFullyResolvedSimple(const MCAssembler &Asm,
114 const MCValue Target,
115 const MCSection *BaseSection) {
116 // The effective fixup address is
117 // addr(atom(A)) + offset(A)
118 // - addr(atom(B)) - offset(B)
119 // - addr(<base symbol>) + <fixup offset from base symbol>
120 // and the offsets are not relocatable, so the fixup is fully resolved when
121 // addr(atom(A)) - addr(atom(B)) - addr(<base symbol>)) == 0.
123 // The simple (Darwin, except on x86_64) way of dealing with this was to
124 // assume that any reference to a temporary symbol *must* be a temporary
125 // symbol in the same atom, unless the sections differ. Therefore, any PCrel
126 // relocation to a temporary symbol (in the same section) is fully
127 // resolved. This also works in conjunction with absolutized .set, which
128 // requires the compiler to use .set to absolutize the differences between
129 // symbols which the compiler knows to be assembly time constants, so we don't
130 // need to worry about considering symbol differences fully resolved.
132 // Non-relative fixups are only resolved if constant.
134 return Target.isAbsolute();
136 // Otherwise, relative fixups are only resolved if not a difference and the
137 // target is a temporary in the same section.
138 if (Target.isAbsolute() || Target.getSymB())
141 const MCSymbol *A = &Target.getSymA()->getSymbol();
142 if (!A->isTemporary() || !A->isInSection() ||
143 &A->getSection() != BaseSection)
151 class MachObjectWriter : public MCObjectWriter {
152 /// MachSymbolData - Helper struct for containing some precomputed information
154 struct MachSymbolData {
155 MCSymbolData *SymbolData;
156 uint64_t StringIndex;
157 uint8_t SectionIndex;
159 // Support lexicographic sorting.
160 bool operator<(const MachSymbolData &RHS) const {
161 return SymbolData->getSymbol().getName() <
162 RHS.SymbolData->getSymbol().getName();
166 /// The target specific Mach-O writer instance.
167 llvm::OwningPtr<MCMachObjectTargetWriter> TargetObjectWriter;
169 /// @name Relocation Data
172 llvm::DenseMap<const MCSectionData*,
173 std::vector<macho::RelocationEntry> > Relocations;
174 llvm::DenseMap<const MCSectionData*, unsigned> IndirectSymBase;
177 /// @name Symbol Table Data
180 SmallString<256> StringTable;
181 std::vector<MachSymbolData> LocalSymbolData;
182 std::vector<MachSymbolData> ExternalSymbolData;
183 std::vector<MachSymbolData> UndefinedSymbolData;
188 /// @name Utility Methods
191 bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind) {
192 const MCFixupKindInfo &FKI = Asm.getBackend().getFixupKindInfo(
195 return FKI.Flags & MCFixupKindInfo::FKF_IsPCRel;
200 SectionAddrMap SectionAddress;
201 uint64_t getSectionAddress(const MCSectionData* SD) const {
202 return SectionAddress.lookup(SD);
204 uint64_t getSymbolAddress(const MCSymbolData* SD,
205 const MCAsmLayout &Layout) const {
206 return getSectionAddress(SD->getFragment()->getParent()) +
207 Layout.getSymbolOffset(SD);
209 uint64_t getFragmentAddress(const MCFragment *Fragment,
210 const MCAsmLayout &Layout) const {
211 return getSectionAddress(Fragment->getParent()) +
212 Layout.getFragmentOffset(Fragment);
215 uint64_t getPaddingSize(const MCSectionData *SD,
216 const MCAsmLayout &Layout) const {
217 uint64_t EndAddr = getSectionAddress(SD) + Layout.getSectionAddressSize(SD);
218 unsigned Next = SD->getLayoutOrder() + 1;
219 if (Next >= Layout.getSectionOrder().size())
222 const MCSectionData &NextSD = *Layout.getSectionOrder()[Next];
223 if (NextSD.getSection().isVirtualSection())
225 return OffsetToAlignment(EndAddr, NextSD.getAlignment());
229 MachObjectWriter(MCMachObjectTargetWriter *MOTW, raw_ostream &_OS,
230 bool _IsLittleEndian)
231 : MCObjectWriter(_OS, _IsLittleEndian), TargetObjectWriter(MOTW) {
234 /// @name Target Writer Proxy Accessors
237 bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
241 void WriteHeader(unsigned NumLoadCommands, unsigned LoadCommandsSize,
242 bool SubsectionsViaSymbols) {
245 if (SubsectionsViaSymbols)
246 Flags |= macho::HF_SubsectionsViaSymbols;
248 // struct mach_header (28 bytes) or
249 // struct mach_header_64 (32 bytes)
251 uint64_t Start = OS.tell();
254 Write32(is64Bit() ? macho::HM_Object64 : macho::HM_Object32);
256 Write32(TargetObjectWriter->getCPUType());
257 Write32(TargetObjectWriter->getCPUSubtype());
259 Write32(macho::HFT_Object);
260 Write32(NumLoadCommands);
261 Write32(LoadCommandsSize);
264 Write32(0); // reserved
266 assert(OS.tell() - Start == is64Bit() ?
267 macho::Header64Size : macho::Header32Size);
270 /// WriteSegmentLoadCommand - Write a segment load command.
272 /// \arg NumSections - The number of sections in this segment.
273 /// \arg SectionDataSize - The total size of the sections.
274 void WriteSegmentLoadCommand(unsigned NumSections,
276 uint64_t SectionDataStartOffset,
277 uint64_t SectionDataSize) {
278 // struct segment_command (56 bytes) or
279 // struct segment_command_64 (72 bytes)
281 uint64_t Start = OS.tell();
284 unsigned SegmentLoadCommandSize =
285 is64Bit() ? macho::SegmentLoadCommand64Size:
286 macho::SegmentLoadCommand32Size;
287 Write32(is64Bit() ? macho::LCT_Segment64 : macho::LCT_Segment);
288 Write32(SegmentLoadCommandSize +
289 NumSections * (is64Bit() ? macho::Section64Size :
290 macho::Section32Size));
294 Write64(0); // vmaddr
295 Write64(VMSize); // vmsize
296 Write64(SectionDataStartOffset); // file offset
297 Write64(SectionDataSize); // file size
299 Write32(0); // vmaddr
300 Write32(VMSize); // vmsize
301 Write32(SectionDataStartOffset); // file offset
302 Write32(SectionDataSize); // file size
304 Write32(0x7); // maxprot
305 Write32(0x7); // initprot
306 Write32(NumSections);
309 assert(OS.tell() - Start == SegmentLoadCommandSize);
312 void WriteSection(const MCAssembler &Asm, const MCAsmLayout &Layout,
313 const MCSectionData &SD, uint64_t FileOffset,
314 uint64_t RelocationsStart, unsigned NumRelocations) {
315 uint64_t SectionSize = Layout.getSectionAddressSize(&SD);
317 // The offset is unused for virtual sections.
318 if (SD.getSection().isVirtualSection()) {
319 assert(Layout.getSectionFileSize(&SD) == 0 && "Invalid file size!");
323 // struct section (68 bytes) or
324 // struct section_64 (80 bytes)
326 uint64_t Start = OS.tell();
329 const MCSectionMachO &Section = cast<MCSectionMachO>(SD.getSection());
330 WriteBytes(Section.getSectionName(), 16);
331 WriteBytes(Section.getSegmentName(), 16);
333 Write64(getSectionAddress(&SD)); // address
334 Write64(SectionSize); // size
336 Write32(getSectionAddress(&SD)); // address
337 Write32(SectionSize); // size
341 unsigned Flags = Section.getTypeAndAttributes();
342 if (SD.hasInstructions())
343 Flags |= MCSectionMachO::S_ATTR_SOME_INSTRUCTIONS;
345 assert(isPowerOf2_32(SD.getAlignment()) && "Invalid alignment!");
346 Write32(Log2_32(SD.getAlignment()));
347 Write32(NumRelocations ? RelocationsStart : 0);
348 Write32(NumRelocations);
350 Write32(IndirectSymBase.lookup(&SD)); // reserved1
351 Write32(Section.getStubSize()); // reserved2
353 Write32(0); // reserved3
355 assert(OS.tell() - Start == is64Bit() ? macho::Section64Size :
356 macho::Section32Size);
359 void WriteSymtabLoadCommand(uint32_t SymbolOffset, uint32_t NumSymbols,
360 uint32_t StringTableOffset,
361 uint32_t StringTableSize) {
362 // struct symtab_command (24 bytes)
364 uint64_t Start = OS.tell();
367 Write32(macho::LCT_Symtab);
368 Write32(macho::SymtabLoadCommandSize);
369 Write32(SymbolOffset);
371 Write32(StringTableOffset);
372 Write32(StringTableSize);
374 assert(OS.tell() - Start == macho::SymtabLoadCommandSize);
377 void WriteDysymtabLoadCommand(uint32_t FirstLocalSymbol,
378 uint32_t NumLocalSymbols,
379 uint32_t FirstExternalSymbol,
380 uint32_t NumExternalSymbols,
381 uint32_t FirstUndefinedSymbol,
382 uint32_t NumUndefinedSymbols,
383 uint32_t IndirectSymbolOffset,
384 uint32_t NumIndirectSymbols) {
385 // struct dysymtab_command (80 bytes)
387 uint64_t Start = OS.tell();
390 Write32(macho::LCT_Dysymtab);
391 Write32(macho::DysymtabLoadCommandSize);
392 Write32(FirstLocalSymbol);
393 Write32(NumLocalSymbols);
394 Write32(FirstExternalSymbol);
395 Write32(NumExternalSymbols);
396 Write32(FirstUndefinedSymbol);
397 Write32(NumUndefinedSymbols);
398 Write32(0); // tocoff
400 Write32(0); // modtaboff
401 Write32(0); // nmodtab
402 Write32(0); // extrefsymoff
403 Write32(0); // nextrefsyms
404 Write32(IndirectSymbolOffset);
405 Write32(NumIndirectSymbols);
406 Write32(0); // extreloff
407 Write32(0); // nextrel
408 Write32(0); // locreloff
409 Write32(0); // nlocrel
411 assert(OS.tell() - Start == macho::DysymtabLoadCommandSize);
414 void WriteNlist(MachSymbolData &MSD, const MCAsmLayout &Layout) {
415 MCSymbolData &Data = *MSD.SymbolData;
416 const MCSymbol &Symbol = Data.getSymbol();
418 uint16_t Flags = Data.getFlags();
419 uint32_t Address = 0;
421 // Set the N_TYPE bits. See <mach-o/nlist.h>.
423 // FIXME: Are the prebound or indirect fields possible here?
424 if (Symbol.isUndefined())
425 Type = macho::STT_Undefined;
426 else if (Symbol.isAbsolute())
427 Type = macho::STT_Absolute;
429 Type = macho::STT_Section;
431 // FIXME: Set STAB bits.
433 if (Data.isPrivateExtern())
434 Type |= macho::STF_PrivateExtern;
437 if (Data.isExternal() || Symbol.isUndefined())
438 Type |= macho::STF_External;
440 // Compute the symbol address.
441 if (Symbol.isDefined()) {
442 if (Symbol.isAbsolute()) {
443 Address = cast<MCConstantExpr>(Symbol.getVariableValue())->getValue();
445 Address = getSymbolAddress(&Data, Layout);
447 } else if (Data.isCommon()) {
448 // Common symbols are encoded with the size in the address
449 // field, and their alignment in the flags.
450 Address = Data.getCommonSize();
452 // Common alignment is packed into the 'desc' bits.
453 if (unsigned Align = Data.getCommonAlignment()) {
454 unsigned Log2Size = Log2_32(Align);
455 assert((1U << Log2Size) == Align && "Invalid 'common' alignment!");
457 report_fatal_error("invalid 'common' alignment '" +
459 // FIXME: Keep this mask with the SymbolFlags enumeration.
460 Flags = (Flags & 0xF0FF) | (Log2Size << 8);
464 // struct nlist (12 bytes)
466 Write32(MSD.StringIndex);
468 Write8(MSD.SectionIndex);
470 // The Mach-O streamer uses the lowest 16-bits of the flags for the 'desc'
479 // FIXME: We really need to improve the relocation validation. Basically, we
480 // want to implement a separate computation which evaluates the relocation
481 // entry as the linker would, and verifies that the resultant fixup value is
482 // exactly what the encoder wanted. This will catch several classes of
485 // - Relocation entry bugs, the two algorithms are unlikely to have the same
488 // - Relaxation issues, where we forget to relax something.
490 // - Input errors, where something cannot be correctly encoded. 'as' allows
491 // these through in many cases.
493 static bool isFixupKindRIPRel(unsigned Kind) {
494 return Kind == X86::reloc_riprel_4byte ||
495 Kind == X86::reloc_riprel_4byte_movq_load;
497 void RecordX86_64Relocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
498 const MCFragment *Fragment,
499 const MCFixup &Fixup, MCValue Target,
500 uint64_t &FixedValue) {
501 unsigned IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
502 unsigned IsRIPRel = isFixupKindRIPRel(Fixup.getKind());
503 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
506 uint32_t FixupOffset =
507 Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
508 uint32_t FixupAddress =
509 getFragmentAddress(Fragment, Layout) + Fixup.getOffset();
512 unsigned IsExtern = 0;
515 Value = Target.getConstant();
518 // Compensate for the relocation offset, Darwin x86_64 relocations only
519 // have the addend and appear to have attempted to define it to be the
520 // actual expression addend without the PCrel bias. However, instructions
521 // with data following the relocation are not accomodated for (see comment
522 // below regarding SIGNED{1,2,4}), so it isn't exactly that either.
523 Value += 1LL << Log2Size;
526 if (Target.isAbsolute()) { // constant
527 // SymbolNum of 0 indicates the absolute section.
528 Type = macho::RIT_X86_64_Unsigned;
531 // FIXME: I believe this is broken, I don't think the linker can
532 // understand it. I think it would require a local relocation, but I'm not
533 // sure if that would work either. The official way to get an absolute
534 // PCrel relocation is to use an absolute symbol (which we don't support
538 Type = macho::RIT_X86_64_Branch;
540 } else if (Target.getSymB()) { // A - B + constant
541 const MCSymbol *A = &Target.getSymA()->getSymbol();
542 MCSymbolData &A_SD = Asm.getSymbolData(*A);
543 const MCSymbolData *A_Base = Asm.getAtom(&A_SD);
545 const MCSymbol *B = &Target.getSymB()->getSymbol();
546 MCSymbolData &B_SD = Asm.getSymbolData(*B);
547 const MCSymbolData *B_Base = Asm.getAtom(&B_SD);
549 // Neither symbol can be modified.
550 if (Target.getSymA()->getKind() != MCSymbolRefExpr::VK_None ||
551 Target.getSymB()->getKind() != MCSymbolRefExpr::VK_None)
552 report_fatal_error("unsupported relocation of modified symbol");
554 // We don't support PCrel relocations of differences. Darwin 'as' doesn't
555 // implement most of these correctly.
557 report_fatal_error("unsupported pc-relative relocation of difference");
559 // The support for the situation where one or both of the symbols would
560 // require a local relocation is handled just like if the symbols were
561 // external. This is certainly used in the case of debug sections where
562 // the section has only temporary symbols and thus the symbols don't have
563 // base symbols. This is encoded using the section ordinal and
564 // non-extern relocation entries.
566 // Darwin 'as' doesn't emit correct relocations for this (it ends up with
567 // a single SIGNED relocation); reject it for now. Except the case where
568 // both symbols don't have a base, equal but both NULL.
569 if (A_Base == B_Base && A_Base)
570 report_fatal_error("unsupported relocation with identical base");
572 Value += getSymbolAddress(&A_SD, Layout) -
573 (A_Base == NULL ? 0 : getSymbolAddress(A_Base, Layout));
574 Value -= getSymbolAddress(&B_SD, Layout) -
575 (B_Base == NULL ? 0 : getSymbolAddress(B_Base, Layout));
578 Index = A_Base->getIndex();
582 Index = A_SD.getFragment()->getParent()->getOrdinal() + 1;
585 Type = macho::RIT_X86_64_Unsigned;
587 macho::RelocationEntry MRE;
588 MRE.Word0 = FixupOffset;
589 MRE.Word1 = ((Index << 0) |
594 Relocations[Fragment->getParent()].push_back(MRE);
597 Index = B_Base->getIndex();
601 Index = B_SD.getFragment()->getParent()->getOrdinal() + 1;
604 Type = macho::RIT_X86_64_Subtractor;
606 const MCSymbol *Symbol = &Target.getSymA()->getSymbol();
607 MCSymbolData &SD = Asm.getSymbolData(*Symbol);
608 const MCSymbolData *Base = Asm.getAtom(&SD);
610 // Relocations inside debug sections always use local relocations when
611 // possible. This seems to be done because the debugger doesn't fully
612 // understand x86_64 relocation entries, and expects to find values that
613 // have already been fixed up.
614 if (Symbol->isInSection()) {
615 const MCSectionMachO &Section = static_cast<const MCSectionMachO&>(
616 Fragment->getParent()->getSection());
617 if (Section.hasAttribute(MCSectionMachO::S_ATTR_DEBUG))
621 // x86_64 almost always uses external relocations, except when there is no
622 // symbol to use as a base address (a local symbol with no preceeding
623 // non-local symbol).
625 Index = Base->getIndex();
628 // Add the local offset, if needed.
630 Value += Layout.getSymbolOffset(&SD) - Layout.getSymbolOffset(Base);
631 } else if (Symbol->isInSection()) {
632 // The index is the section ordinal (1-based).
633 Index = SD.getFragment()->getParent()->getOrdinal() + 1;
635 Value += getSymbolAddress(&SD, Layout);
638 Value -= FixupAddress + (1 << Log2Size);
639 } else if (Symbol->isVariable()) {
640 const MCExpr *Value = Symbol->getVariableValue();
642 bool isAbs = Value->EvaluateAsAbsolute(Res, Layout, SectionAddress);
647 report_fatal_error("unsupported relocation of variable '" +
648 Symbol->getName() + "'");
651 report_fatal_error("unsupported relocation of undefined symbol '" +
652 Symbol->getName() + "'");
655 MCSymbolRefExpr::VariantKind Modifier = Target.getSymA()->getKind();
658 if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) {
659 // x86_64 distinguishes movq foo@GOTPCREL so that the linker can
660 // rewrite the movq to an leaq at link time if the symbol ends up in
661 // the same linkage unit.
662 if (unsigned(Fixup.getKind()) == X86::reloc_riprel_4byte_movq_load)
663 Type = macho::RIT_X86_64_GOTLoad;
665 Type = macho::RIT_X86_64_GOT;
666 } else if (Modifier == MCSymbolRefExpr::VK_TLVP) {
667 Type = macho::RIT_X86_64_TLV;
668 } else if (Modifier != MCSymbolRefExpr::VK_None) {
669 report_fatal_error("unsupported symbol modifier in relocation");
671 Type = macho::RIT_X86_64_Signed;
673 // The Darwin x86_64 relocation format has a problem where it cannot
674 // encode an address (L<foo> + <constant>) which is outside the atom
675 // containing L<foo>. Generally, this shouldn't occur but it does
676 // happen when we have a RIPrel instruction with data following the
677 // relocation entry (e.g., movb $012, L0(%rip)). Even with the PCrel
678 // adjustment Darwin x86_64 uses, the offset is still negative and
679 // the linker has no way to recognize this.
681 // To work around this, Darwin uses several special relocation types
682 // to indicate the offsets. However, the specification or
683 // implementation of these seems to also be incomplete; they should
684 // adjust the addend as well based on the actual encoded instruction
685 // (the additional bias), but instead appear to just look at the
687 switch (-(Target.getConstant() + (1LL << Log2Size))) {
688 case 1: Type = macho::RIT_X86_64_Signed1; break;
689 case 2: Type = macho::RIT_X86_64_Signed2; break;
690 case 4: Type = macho::RIT_X86_64_Signed4; break;
694 if (Modifier != MCSymbolRefExpr::VK_None)
695 report_fatal_error("unsupported symbol modifier in branch "
698 Type = macho::RIT_X86_64_Branch;
701 if (Modifier == MCSymbolRefExpr::VK_GOT) {
702 Type = macho::RIT_X86_64_GOT;
703 } else if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) {
704 // GOTPCREL is allowed as a modifier on non-PCrel instructions, in
705 // which case all we do is set the PCrel bit in the relocation entry;
706 // this is used with exception handling, for example. The source is
707 // required to include any necessary offset directly.
708 Type = macho::RIT_X86_64_GOT;
710 } else if (Modifier == MCSymbolRefExpr::VK_TLVP) {
711 report_fatal_error("TLVP symbol modifier should have been rip-rel");
712 } else if (Modifier != MCSymbolRefExpr::VK_None)
713 report_fatal_error("unsupported symbol modifier in relocation");
715 Type = macho::RIT_X86_64_Unsigned;
719 // x86_64 always writes custom values into the fixups.
722 // struct relocation_info (8 bytes)
723 macho::RelocationEntry MRE;
724 MRE.Word0 = FixupOffset;
725 MRE.Word1 = ((Index << 0) |
730 Relocations[Fragment->getParent()].push_back(MRE);
733 void RecordScatteredRelocation(const MCAssembler &Asm,
734 const MCAsmLayout &Layout,
735 const MCFragment *Fragment,
736 const MCFixup &Fixup, MCValue Target,
737 uint64_t &FixedValue) {
738 uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
739 unsigned IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
740 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
741 unsigned Type = macho::RIT_Vanilla;
744 const MCSymbol *A = &Target.getSymA()->getSymbol();
745 MCSymbolData *A_SD = &Asm.getSymbolData(*A);
747 if (!A_SD->getFragment())
748 report_fatal_error("symbol '" + A->getName() +
749 "' can not be undefined in a subtraction expression");
751 uint32_t Value = getSymbolAddress(A_SD, Layout);
752 uint64_t SecAddr = getSectionAddress(A_SD->getFragment()->getParent());
753 FixedValue += SecAddr;
756 if (const MCSymbolRefExpr *B = Target.getSymB()) {
757 MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
759 if (!B_SD->getFragment())
760 report_fatal_error("symbol '" + B->getSymbol().getName() +
761 "' can not be undefined in a subtraction expression");
763 // Select the appropriate difference relocation type.
765 // Note that there is no longer any semantic difference between these two
766 // relocation types from the linkers point of view, this is done solely
767 // for pedantic compatibility with 'as'.
768 Type = A_SD->isExternal() ? macho::RIT_Difference :
769 macho::RIT_Generic_LocalDifference;
770 Value2 = getSymbolAddress(B_SD, Layout);
771 FixedValue -= getSectionAddress(B_SD->getFragment()->getParent());
774 // Relocations are written out in reverse order, so the PAIR comes first.
775 if (Type == macho::RIT_Difference ||
776 Type == macho::RIT_Generic_LocalDifference) {
777 macho::RelocationEntry MRE;
778 MRE.Word0 = ((0 << 0) |
779 (macho::RIT_Pair << 24) |
782 macho::RF_Scattered);
784 Relocations[Fragment->getParent()].push_back(MRE);
787 macho::RelocationEntry MRE;
788 MRE.Word0 = ((FixupOffset << 0) |
792 macho::RF_Scattered);
794 Relocations[Fragment->getParent()].push_back(MRE);
797 void RecordTLVPRelocation(const MCAssembler &Asm,
798 const MCAsmLayout &Layout,
799 const MCFragment *Fragment,
800 const MCFixup &Fixup, MCValue Target,
801 uint64_t &FixedValue) {
802 assert(Target.getSymA()->getKind() == MCSymbolRefExpr::VK_TLVP &&
804 "Should only be called with a 32-bit TLVP relocation!");
806 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
807 uint32_t Value = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
808 unsigned IsPCRel = 0;
810 // Get the symbol data.
811 MCSymbolData *SD_A = &Asm.getSymbolData(Target.getSymA()->getSymbol());
812 unsigned Index = SD_A->getIndex();
814 // We're only going to have a second symbol in pic mode and it'll be a
815 // subtraction from the picbase. For 32-bit pic the addend is the difference
816 // between the picbase and the next address. For 32-bit static the addend
818 if (Target.getSymB()) {
819 // If this is a subtraction then we're pcrel.
820 uint32_t FixupAddress =
821 getFragmentAddress(Fragment, Layout) + Fixup.getOffset();
822 MCSymbolData *SD_B = &Asm.getSymbolData(Target.getSymB()->getSymbol());
824 FixedValue = (FixupAddress - getSymbolAddress(SD_B, Layout) +
825 Target.getConstant());
826 FixedValue += 1ULL << Log2Size;
831 // struct relocation_info (8 bytes)
832 macho::RelocationEntry MRE;
834 MRE.Word1 = ((Index << 0) |
837 (1 << 27) | // Extern
838 (macho::RIT_Generic_TLV << 28)); // Type
839 Relocations[Fragment->getParent()].push_back(MRE);
842 void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
843 const MCFragment *Fragment, const MCFixup &Fixup,
844 MCValue Target, uint64_t &FixedValue) {
846 RecordX86_64Relocation(Asm, Layout, Fragment, Fixup, Target, FixedValue);
850 unsigned IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
851 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
853 // If this is a 32-bit TLVP reloc it's handled a bit differently.
854 if (Target.getSymA() &&
855 Target.getSymA()->getKind() == MCSymbolRefExpr::VK_TLVP) {
856 RecordTLVPRelocation(Asm, Layout, Fragment, Fixup, Target, FixedValue);
860 // If this is a difference or a defined symbol plus an offset, then we need
861 // a scattered relocation entry.
862 // Differences always require scattered relocations.
863 if (Target.getSymB())
864 return RecordScatteredRelocation(Asm, Layout, Fragment, Fixup,
867 // Get the symbol data, if any.
868 MCSymbolData *SD = 0;
869 if (Target.getSymA())
870 SD = &Asm.getSymbolData(Target.getSymA()->getSymbol());
872 // If this is an internal relocation with an offset, it also needs a
873 // scattered relocation entry.
874 uint32_t Offset = Target.getConstant();
876 Offset += 1 << Log2Size;
877 if (Offset && SD && !doesSymbolRequireExternRelocation(SD))
878 return RecordScatteredRelocation(Asm, Layout, Fragment, Fixup,
882 uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
884 unsigned IsExtern = 0;
887 if (Target.isAbsolute()) { // constant
888 // SymbolNum of 0 indicates the absolute section.
890 // FIXME: Currently, these are never generated (see code below). I cannot
891 // find a case where they are actually emitted.
892 Type = macho::RIT_Vanilla;
893 } else if (SD->getSymbol().isVariable()) {
894 const MCExpr *Value = SD->getSymbol().getVariableValue();
896 bool isAbs = Value->EvaluateAsAbsolute(Res, Layout, SectionAddress);
901 report_fatal_error("unsupported relocation of variable '" +
902 SD->getSymbol().getName() + "'");
905 // Check whether we need an external or internal relocation.
906 if (doesSymbolRequireExternRelocation(SD)) {
908 Index = SD->getIndex();
909 // For external relocations, make sure to offset the fixup value to
910 // compensate for the addend of the symbol address, if it was
911 // undefined. This occurs with weak definitions, for example.
912 if (!SD->Symbol->isUndefined())
913 FixedValue -= Layout.getSymbolOffset(SD);
915 // The index is the section ordinal (1-based).
916 Index = SD->getFragment()->getParent()->getOrdinal() + 1;
917 FixedValue += getSectionAddress(SD->getFragment()->getParent());
920 FixedValue -= getSectionAddress(Fragment->getParent());
922 Type = macho::RIT_Vanilla;
925 // struct relocation_info (8 bytes)
926 macho::RelocationEntry MRE;
927 MRE.Word0 = FixupOffset;
928 MRE.Word1 = ((Index << 0) |
933 Relocations[Fragment->getParent()].push_back(MRE);
936 void BindIndirectSymbols(MCAssembler &Asm) {
937 // This is the point where 'as' creates actual symbols for indirect symbols
938 // (in the following two passes). It would be easier for us to do this
939 // sooner when we see the attribute, but that makes getting the order in the
940 // symbol table much more complicated than it is worth.
942 // FIXME: Revisit this when the dust settles.
944 // Bind non lazy symbol pointers first.
945 unsigned IndirectIndex = 0;
946 for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
947 ie = Asm.indirect_symbol_end(); it != ie; ++it, ++IndirectIndex) {
948 const MCSectionMachO &Section =
949 cast<MCSectionMachO>(it->SectionData->getSection());
951 if (Section.getType() != MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS)
954 // Initialize the section indirect symbol base, if necessary.
955 if (!IndirectSymBase.count(it->SectionData))
956 IndirectSymBase[it->SectionData] = IndirectIndex;
958 Asm.getOrCreateSymbolData(*it->Symbol);
961 // Then lazy symbol pointers and symbol stubs.
963 for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
964 ie = Asm.indirect_symbol_end(); it != ie; ++it, ++IndirectIndex) {
965 const MCSectionMachO &Section =
966 cast<MCSectionMachO>(it->SectionData->getSection());
968 if (Section.getType() != MCSectionMachO::S_LAZY_SYMBOL_POINTERS &&
969 Section.getType() != MCSectionMachO::S_SYMBOL_STUBS)
972 // Initialize the section indirect symbol base, if necessary.
973 if (!IndirectSymBase.count(it->SectionData))
974 IndirectSymBase[it->SectionData] = IndirectIndex;
976 // Set the symbol type to undefined lazy, but only on construction.
978 // FIXME: Do not hardcode.
980 MCSymbolData &Entry = Asm.getOrCreateSymbolData(*it->Symbol, &Created);
982 Entry.setFlags(Entry.getFlags() | 0x0001);
986 /// ComputeSymbolTable - Compute the symbol table data
988 /// \param StringTable [out] - The string table data.
989 /// \param StringIndexMap [out] - Map from symbol names to offsets in the
991 void ComputeSymbolTable(MCAssembler &Asm, SmallString<256> &StringTable,
992 std::vector<MachSymbolData> &LocalSymbolData,
993 std::vector<MachSymbolData> &ExternalSymbolData,
994 std::vector<MachSymbolData> &UndefinedSymbolData) {
995 // Build section lookup table.
996 DenseMap<const MCSection*, uint8_t> SectionIndexMap;
998 for (MCAssembler::iterator it = Asm.begin(),
999 ie = Asm.end(); it != ie; ++it, ++Index)
1000 SectionIndexMap[&it->getSection()] = Index;
1001 assert(Index <= 256 && "Too many sections!");
1003 // Index 0 is always the empty string.
1004 StringMap<uint64_t> StringIndexMap;
1005 StringTable += '\x00';
1007 // Build the symbol arrays and the string table, but only for non-local
1010 // The particular order that we collect the symbols and create the string
1011 // table, then sort the symbols is chosen to match 'as'. Even though it
1012 // doesn't matter for correctness, this is important for letting us diff .o
1014 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
1015 ie = Asm.symbol_end(); it != ie; ++it) {
1016 const MCSymbol &Symbol = it->getSymbol();
1018 // Ignore non-linker visible symbols.
1019 if (!Asm.isSymbolLinkerVisible(it->getSymbol()))
1022 if (!it->isExternal() && !Symbol.isUndefined())
1025 uint64_t &Entry = StringIndexMap[Symbol.getName()];
1027 Entry = StringTable.size();
1028 StringTable += Symbol.getName();
1029 StringTable += '\x00';
1033 MSD.SymbolData = it;
1034 MSD.StringIndex = Entry;
1036 if (Symbol.isUndefined()) {
1037 MSD.SectionIndex = 0;
1038 UndefinedSymbolData.push_back(MSD);
1039 } else if (Symbol.isAbsolute()) {
1040 MSD.SectionIndex = 0;
1041 ExternalSymbolData.push_back(MSD);
1043 MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
1044 assert(MSD.SectionIndex && "Invalid section index!");
1045 ExternalSymbolData.push_back(MSD);
1049 // Now add the data for local symbols.
1050 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
1051 ie = Asm.symbol_end(); it != ie; ++it) {
1052 const MCSymbol &Symbol = it->getSymbol();
1054 // Ignore non-linker visible symbols.
1055 if (!Asm.isSymbolLinkerVisible(it->getSymbol()))
1058 if (it->isExternal() || Symbol.isUndefined())
1061 uint64_t &Entry = StringIndexMap[Symbol.getName()];
1063 Entry = StringTable.size();
1064 StringTable += Symbol.getName();
1065 StringTable += '\x00';
1069 MSD.SymbolData = it;
1070 MSD.StringIndex = Entry;
1072 if (Symbol.isAbsolute()) {
1073 MSD.SectionIndex = 0;
1074 LocalSymbolData.push_back(MSD);
1076 MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
1077 assert(MSD.SectionIndex && "Invalid section index!");
1078 LocalSymbolData.push_back(MSD);
1082 // External and undefined symbols are required to be in lexicographic order.
1083 std::sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
1084 std::sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
1086 // Set the symbol indices.
1088 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
1089 LocalSymbolData[i].SymbolData->setIndex(Index++);
1090 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
1091 ExternalSymbolData[i].SymbolData->setIndex(Index++);
1092 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
1093 UndefinedSymbolData[i].SymbolData->setIndex(Index++);
1095 // The string table is padded to a multiple of 4.
1096 while (StringTable.size() % 4)
1097 StringTable += '\x00';
1100 void computeSectionAddresses(const MCAssembler &Asm,
1101 const MCAsmLayout &Layout) {
1102 uint64_t StartAddress = 0;
1103 const SmallVectorImpl<MCSectionData*> &Order = Layout.getSectionOrder();
1104 for (int i = 0, n = Order.size(); i != n ; ++i) {
1105 const MCSectionData *SD = Order[i];
1106 StartAddress = RoundUpToAlignment(StartAddress, SD->getAlignment());
1107 SectionAddress[SD] = StartAddress;
1108 StartAddress += Layout.getSectionAddressSize(SD);
1109 // Explicitly pad the section to match the alignment requirements of the
1110 // following one. This is for 'gas' compatibility, it shouldn't
1111 /// strictly be necessary.
1112 StartAddress += getPaddingSize(SD, Layout);
1116 void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout) {
1117 computeSectionAddresses(Asm, Layout);
1119 // Create symbol data for any indirect symbols.
1120 BindIndirectSymbols(Asm);
1122 // Compute symbol table information and bind symbol indices.
1123 ComputeSymbolTable(Asm, StringTable, LocalSymbolData, ExternalSymbolData,
1124 UndefinedSymbolData);
1127 bool IsSymbolRefDifferenceFullyResolved(const MCAssembler &Asm,
1128 const MCSymbolRefExpr *A,
1129 const MCSymbolRefExpr *B,
1134 if (!TargetObjectWriter->useAggressiveSymbolFolding())
1137 // The effective address is
1138 // addr(atom(A)) + offset(A)
1139 // - addr(atom(B)) - offset(B)
1140 // and the offsets are not relocatable, so the fixup is fully resolved when
1141 // addr(atom(A)) - addr(atom(B)) == 0.
1142 const MCSymbolData *A_Base = 0, *B_Base = 0;
1144 // Modified symbol references cannot be resolved.
1145 if (A->getKind() != MCSymbolRefExpr::VK_None ||
1146 B->getKind() != MCSymbolRefExpr::VK_None)
1149 A_Base = Asm.getAtom(&Asm.getSymbolData(A->getSymbol()));
1153 B_Base = Asm.getAtom(&Asm.getSymbolData(B->getSymbol()));
1157 // If the atoms are the same, they are guaranteed to have the same address.
1158 if (A_Base == B_Base)
1161 // Otherwise, we can't prove this is fully resolved.
1165 bool IsFixupFullyResolved(const MCAssembler &Asm,
1166 const MCValue Target,
1168 const MCFragment *DF) const {
1169 // Otherwise, determine whether this value is actually resolved; scattering
1170 // may cause atoms to move.
1172 // Check if we are using the "simple" resolution algorithm (e.g.,
1174 if (!Asm.getBackend().hasReliableSymbolDifference()) {
1175 const MCSection *BaseSection = 0;
1177 BaseSection = &DF->getParent()->getSection();
1179 return isScatteredFixupFullyResolvedSimple(Asm, Target, BaseSection);
1182 // Otherwise, compute the proper answer as reliably as possible.
1184 // If this is a PCrel relocation, find the base atom (identified by its
1185 // symbol) that the fixup value is relative to.
1186 const MCSymbolData *BaseSymbol = 0;
1188 BaseSymbol = DF->getAtom();
1193 return isScatteredFixupFullyResolved(Asm, Target, BaseSymbol);
1196 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout) {
1197 unsigned NumSections = Asm.size();
1199 // The section data starts after the header, the segment load command (and
1200 // section headers) and the symbol table.
1201 unsigned NumLoadCommands = 1;
1202 uint64_t LoadCommandsSize = is64Bit() ?
1203 macho::SegmentLoadCommand64Size + NumSections * macho::Section64Size :
1204 macho::SegmentLoadCommand32Size + NumSections * macho::Section32Size;
1206 // Add the symbol table load command sizes, if used.
1207 unsigned NumSymbols = LocalSymbolData.size() + ExternalSymbolData.size() +
1208 UndefinedSymbolData.size();
1210 NumLoadCommands += 2;
1211 LoadCommandsSize += (macho::SymtabLoadCommandSize +
1212 macho::DysymtabLoadCommandSize);
1215 // Compute the total size of the section data, as well as its file size and
1217 uint64_t SectionDataStart = (is64Bit() ? macho::Header64Size :
1218 macho::Header32Size) + LoadCommandsSize;
1219 uint64_t SectionDataSize = 0;
1220 uint64_t SectionDataFileSize = 0;
1221 uint64_t VMSize = 0;
1222 for (MCAssembler::const_iterator it = Asm.begin(),
1223 ie = Asm.end(); it != ie; ++it) {
1224 const MCSectionData &SD = *it;
1225 uint64_t Address = getSectionAddress(&SD);
1226 uint64_t Size = Layout.getSectionAddressSize(&SD);
1227 uint64_t FileSize = Layout.getSectionFileSize(&SD);
1228 FileSize += getPaddingSize(&SD, Layout);
1230 VMSize = std::max(VMSize, Address + Size);
1232 if (SD.getSection().isVirtualSection())
1235 SectionDataSize = std::max(SectionDataSize, Address + Size);
1236 SectionDataFileSize = std::max(SectionDataFileSize, Address + FileSize);
1239 // The section data is padded to 4 bytes.
1241 // FIXME: Is this machine dependent?
1242 unsigned SectionDataPadding = OffsetToAlignment(SectionDataFileSize, 4);
1243 SectionDataFileSize += SectionDataPadding;
1245 // Write the prolog, starting with the header and load command...
1246 WriteHeader(NumLoadCommands, LoadCommandsSize,
1247 Asm.getSubsectionsViaSymbols());
1248 WriteSegmentLoadCommand(NumSections, VMSize,
1249 SectionDataStart, SectionDataSize);
1251 // ... and then the section headers.
1252 uint64_t RelocTableEnd = SectionDataStart + SectionDataFileSize;
1253 for (MCAssembler::const_iterator it = Asm.begin(),
1254 ie = Asm.end(); it != ie; ++it) {
1255 std::vector<macho::RelocationEntry> &Relocs = Relocations[it];
1256 unsigned NumRelocs = Relocs.size();
1257 uint64_t SectionStart = SectionDataStart + getSectionAddress(it);
1258 WriteSection(Asm, Layout, *it, SectionStart, RelocTableEnd, NumRelocs);
1259 RelocTableEnd += NumRelocs * macho::RelocationInfoSize;
1262 // Write the symbol table load command, if used.
1264 unsigned FirstLocalSymbol = 0;
1265 unsigned NumLocalSymbols = LocalSymbolData.size();
1266 unsigned FirstExternalSymbol = FirstLocalSymbol + NumLocalSymbols;
1267 unsigned NumExternalSymbols = ExternalSymbolData.size();
1268 unsigned FirstUndefinedSymbol = FirstExternalSymbol + NumExternalSymbols;
1269 unsigned NumUndefinedSymbols = UndefinedSymbolData.size();
1270 unsigned NumIndirectSymbols = Asm.indirect_symbol_size();
1271 unsigned NumSymTabSymbols =
1272 NumLocalSymbols + NumExternalSymbols + NumUndefinedSymbols;
1273 uint64_t IndirectSymbolSize = NumIndirectSymbols * 4;
1274 uint64_t IndirectSymbolOffset = 0;
1276 // If used, the indirect symbols are written after the section data.
1277 if (NumIndirectSymbols)
1278 IndirectSymbolOffset = RelocTableEnd;
1280 // The symbol table is written after the indirect symbol data.
1281 uint64_t SymbolTableOffset = RelocTableEnd + IndirectSymbolSize;
1283 // The string table is written after symbol table.
1284 uint64_t StringTableOffset =
1285 SymbolTableOffset + NumSymTabSymbols * (is64Bit() ? macho::Nlist64Size :
1286 macho::Nlist32Size);
1287 WriteSymtabLoadCommand(SymbolTableOffset, NumSymTabSymbols,
1288 StringTableOffset, StringTable.size());
1290 WriteDysymtabLoadCommand(FirstLocalSymbol, NumLocalSymbols,
1291 FirstExternalSymbol, NumExternalSymbols,
1292 FirstUndefinedSymbol, NumUndefinedSymbols,
1293 IndirectSymbolOffset, NumIndirectSymbols);
1296 // Write the actual section data.
1297 for (MCAssembler::const_iterator it = Asm.begin(),
1298 ie = Asm.end(); it != ie; ++it) {
1299 Asm.WriteSectionData(it, Layout);
1301 uint64_t Pad = getPaddingSize(it, Layout);
1302 for (unsigned int i = 0; i < Pad; ++i)
1306 // Write the extra padding.
1307 WriteZeros(SectionDataPadding);
1309 // Write the relocation entries.
1310 for (MCAssembler::const_iterator it = Asm.begin(),
1311 ie = Asm.end(); it != ie; ++it) {
1312 // Write the section relocation entries, in reverse order to match 'as'
1313 // (approximately, the exact algorithm is more complicated than this).
1314 std::vector<macho::RelocationEntry> &Relocs = Relocations[it];
1315 for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
1316 Write32(Relocs[e - i - 1].Word0);
1317 Write32(Relocs[e - i - 1].Word1);
1321 // Write the symbol table data, if used.
1323 // Write the indirect symbol entries.
1324 for (MCAssembler::const_indirect_symbol_iterator
1325 it = Asm.indirect_symbol_begin(),
1326 ie = Asm.indirect_symbol_end(); it != ie; ++it) {
1327 // Indirect symbols in the non lazy symbol pointer section have some
1328 // special handling.
1329 const MCSectionMachO &Section =
1330 static_cast<const MCSectionMachO&>(it->SectionData->getSection());
1331 if (Section.getType() == MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS) {
1332 // If this symbol is defined and internal, mark it as such.
1333 if (it->Symbol->isDefined() &&
1334 !Asm.getSymbolData(*it->Symbol).isExternal()) {
1335 uint32_t Flags = macho::ISF_Local;
1336 if (it->Symbol->isAbsolute())
1337 Flags |= macho::ISF_Absolute;
1343 Write32(Asm.getSymbolData(*it->Symbol).getIndex());
1346 // FIXME: Check that offsets match computed ones.
1348 // Write the symbol table entries.
1349 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
1350 WriteNlist(LocalSymbolData[i], Layout);
1351 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
1352 WriteNlist(ExternalSymbolData[i], Layout);
1353 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
1354 WriteNlist(UndefinedSymbolData[i], Layout);
1356 // Write the string table.
1357 OS << StringTable.str();
1364 MCObjectWriter *llvm::createMachObjectWriter(MCMachObjectTargetWriter *MOTW,
1366 bool IsLittleEndian) {
1367 return new MachObjectWriter(MOTW, OS, IsLittleEndian);