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/ARM/ARMFixupKinds.h"
28 #include "../Target/X86/X86FixupKinds.h"
32 using namespace llvm::object;
34 // FIXME: this has been copied from (or to) X86AsmBackend.cpp
35 static unsigned getFixupKindLog2Size(unsigned Kind) {
38 llvm_unreachable("invalid fixup kind!");
40 case FK_Data_1: return 0;
42 case FK_Data_2: return 1;
44 // FIXME: Remove these!!!
45 case X86::reloc_riprel_4byte:
46 case X86::reloc_riprel_4byte_movq_load:
47 case X86::reloc_signed_4byte:
48 case FK_Data_4: return 2;
49 case FK_Data_8: return 3;
53 static bool doesSymbolRequireExternRelocation(MCSymbolData *SD) {
54 // Undefined symbols are always extern.
55 if (SD->Symbol->isUndefined())
58 // References to weak definitions require external relocation entries; the
59 // definition may not always be the one in the same object file.
60 if (SD->getFlags() & SF_WeakDefinition)
63 // Otherwise, we can use an internal relocation.
69 class MachObjectWriter : public MCObjectWriter {
70 /// MachSymbolData - Helper struct for containing some precomputed information
72 struct MachSymbolData {
73 MCSymbolData *SymbolData;
77 // Support lexicographic sorting.
78 bool operator<(const MachSymbolData &RHS) const {
79 return SymbolData->getSymbol().getName() <
80 RHS.SymbolData->getSymbol().getName();
84 /// The target specific Mach-O writer instance.
85 llvm::OwningPtr<MCMachObjectTargetWriter> TargetObjectWriter;
87 /// @name Relocation Data
90 llvm::DenseMap<const MCSectionData*,
91 std::vector<macho::RelocationEntry> > Relocations;
92 llvm::DenseMap<const MCSectionData*, unsigned> IndirectSymBase;
95 /// @name Symbol Table Data
98 SmallString<256> StringTable;
99 std::vector<MachSymbolData> LocalSymbolData;
100 std::vector<MachSymbolData> ExternalSymbolData;
101 std::vector<MachSymbolData> UndefinedSymbolData;
106 /// @name Utility Methods
109 bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind) {
110 const MCFixupKindInfo &FKI = Asm.getBackend().getFixupKindInfo(
113 return FKI.Flags & MCFixupKindInfo::FKF_IsPCRel;
118 SectionAddrMap SectionAddress;
119 uint64_t getSectionAddress(const MCSectionData* SD) const {
120 return SectionAddress.lookup(SD);
122 uint64_t getSymbolAddress(const MCSymbolData* SD,
123 const MCAsmLayout &Layout) const {
124 return getSectionAddress(SD->getFragment()->getParent()) +
125 Layout.getSymbolOffset(SD);
127 uint64_t getFragmentAddress(const MCFragment *Fragment,
128 const MCAsmLayout &Layout) const {
129 return getSectionAddress(Fragment->getParent()) +
130 Layout.getFragmentOffset(Fragment);
133 uint64_t getPaddingSize(const MCSectionData *SD,
134 const MCAsmLayout &Layout) const {
135 uint64_t EndAddr = getSectionAddress(SD) + Layout.getSectionAddressSize(SD);
136 unsigned Next = SD->getLayoutOrder() + 1;
137 if (Next >= Layout.getSectionOrder().size())
140 const MCSectionData &NextSD = *Layout.getSectionOrder()[Next];
141 if (NextSD.getSection().isVirtualSection())
143 return OffsetToAlignment(EndAddr, NextSD.getAlignment());
147 MachObjectWriter(MCMachObjectTargetWriter *MOTW, raw_ostream &_OS,
148 bool _IsLittleEndian)
149 : MCObjectWriter(_OS, _IsLittleEndian), TargetObjectWriter(MOTW) {
152 /// @name Target Writer Proxy Accessors
155 bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
157 uint32_t CPUType = TargetObjectWriter->getCPUType() & ~mach::CTFM_ArchMask;
158 return CPUType == mach::CTM_ARM;
163 void WriteHeader(unsigned NumLoadCommands, unsigned LoadCommandsSize,
164 bool SubsectionsViaSymbols) {
167 if (SubsectionsViaSymbols)
168 Flags |= macho::HF_SubsectionsViaSymbols;
170 // struct mach_header (28 bytes) or
171 // struct mach_header_64 (32 bytes)
173 uint64_t Start = OS.tell();
176 Write32(is64Bit() ? macho::HM_Object64 : macho::HM_Object32);
178 Write32(TargetObjectWriter->getCPUType());
179 Write32(TargetObjectWriter->getCPUSubtype());
181 Write32(macho::HFT_Object);
182 Write32(NumLoadCommands);
183 Write32(LoadCommandsSize);
186 Write32(0); // reserved
188 assert(OS.tell() - Start == is64Bit() ?
189 macho::Header64Size : macho::Header32Size);
192 /// WriteSegmentLoadCommand - Write a segment load command.
194 /// \arg NumSections - The number of sections in this segment.
195 /// \arg SectionDataSize - The total size of the sections.
196 void WriteSegmentLoadCommand(unsigned NumSections,
198 uint64_t SectionDataStartOffset,
199 uint64_t SectionDataSize) {
200 // struct segment_command (56 bytes) or
201 // struct segment_command_64 (72 bytes)
203 uint64_t Start = OS.tell();
206 unsigned SegmentLoadCommandSize =
207 is64Bit() ? macho::SegmentLoadCommand64Size:
208 macho::SegmentLoadCommand32Size;
209 Write32(is64Bit() ? macho::LCT_Segment64 : macho::LCT_Segment);
210 Write32(SegmentLoadCommandSize +
211 NumSections * (is64Bit() ? macho::Section64Size :
212 macho::Section32Size));
216 Write64(0); // vmaddr
217 Write64(VMSize); // vmsize
218 Write64(SectionDataStartOffset); // file offset
219 Write64(SectionDataSize); // file size
221 Write32(0); // vmaddr
222 Write32(VMSize); // vmsize
223 Write32(SectionDataStartOffset); // file offset
224 Write32(SectionDataSize); // file size
226 Write32(0x7); // maxprot
227 Write32(0x7); // initprot
228 Write32(NumSections);
231 assert(OS.tell() - Start == SegmentLoadCommandSize);
234 void WriteSection(const MCAssembler &Asm, const MCAsmLayout &Layout,
235 const MCSectionData &SD, uint64_t FileOffset,
236 uint64_t RelocationsStart, unsigned NumRelocations) {
237 uint64_t SectionSize = Layout.getSectionAddressSize(&SD);
239 // The offset is unused for virtual sections.
240 if (SD.getSection().isVirtualSection()) {
241 assert(Layout.getSectionFileSize(&SD) == 0 && "Invalid file size!");
245 // struct section (68 bytes) or
246 // struct section_64 (80 bytes)
248 uint64_t Start = OS.tell();
251 const MCSectionMachO &Section = cast<MCSectionMachO>(SD.getSection());
252 WriteBytes(Section.getSectionName(), 16);
253 WriteBytes(Section.getSegmentName(), 16);
255 Write64(getSectionAddress(&SD)); // address
256 Write64(SectionSize); // size
258 Write32(getSectionAddress(&SD)); // address
259 Write32(SectionSize); // size
263 unsigned Flags = Section.getTypeAndAttributes();
264 if (SD.hasInstructions())
265 Flags |= MCSectionMachO::S_ATTR_SOME_INSTRUCTIONS;
267 assert(isPowerOf2_32(SD.getAlignment()) && "Invalid alignment!");
268 Write32(Log2_32(SD.getAlignment()));
269 Write32(NumRelocations ? RelocationsStart : 0);
270 Write32(NumRelocations);
272 Write32(IndirectSymBase.lookup(&SD)); // reserved1
273 Write32(Section.getStubSize()); // reserved2
275 Write32(0); // reserved3
277 assert(OS.tell() - Start == is64Bit() ? macho::Section64Size :
278 macho::Section32Size);
281 void WriteSymtabLoadCommand(uint32_t SymbolOffset, uint32_t NumSymbols,
282 uint32_t StringTableOffset,
283 uint32_t StringTableSize) {
284 // struct symtab_command (24 bytes)
286 uint64_t Start = OS.tell();
289 Write32(macho::LCT_Symtab);
290 Write32(macho::SymtabLoadCommandSize);
291 Write32(SymbolOffset);
293 Write32(StringTableOffset);
294 Write32(StringTableSize);
296 assert(OS.tell() - Start == macho::SymtabLoadCommandSize);
299 void WriteDysymtabLoadCommand(uint32_t FirstLocalSymbol,
300 uint32_t NumLocalSymbols,
301 uint32_t FirstExternalSymbol,
302 uint32_t NumExternalSymbols,
303 uint32_t FirstUndefinedSymbol,
304 uint32_t NumUndefinedSymbols,
305 uint32_t IndirectSymbolOffset,
306 uint32_t NumIndirectSymbols) {
307 // struct dysymtab_command (80 bytes)
309 uint64_t Start = OS.tell();
312 Write32(macho::LCT_Dysymtab);
313 Write32(macho::DysymtabLoadCommandSize);
314 Write32(FirstLocalSymbol);
315 Write32(NumLocalSymbols);
316 Write32(FirstExternalSymbol);
317 Write32(NumExternalSymbols);
318 Write32(FirstUndefinedSymbol);
319 Write32(NumUndefinedSymbols);
320 Write32(0); // tocoff
322 Write32(0); // modtaboff
323 Write32(0); // nmodtab
324 Write32(0); // extrefsymoff
325 Write32(0); // nextrefsyms
326 Write32(IndirectSymbolOffset);
327 Write32(NumIndirectSymbols);
328 Write32(0); // extreloff
329 Write32(0); // nextrel
330 Write32(0); // locreloff
331 Write32(0); // nlocrel
333 assert(OS.tell() - Start == macho::DysymtabLoadCommandSize);
336 void WriteNlist(MachSymbolData &MSD, const MCAsmLayout &Layout) {
337 MCSymbolData &Data = *MSD.SymbolData;
338 const MCSymbol &Symbol = Data.getSymbol();
340 uint16_t Flags = Data.getFlags();
341 uint32_t Address = 0;
343 // Set the N_TYPE bits. See <mach-o/nlist.h>.
345 // FIXME: Are the prebound or indirect fields possible here?
346 if (Symbol.isUndefined())
347 Type = macho::STT_Undefined;
348 else if (Symbol.isAbsolute())
349 Type = macho::STT_Absolute;
351 Type = macho::STT_Section;
353 // FIXME: Set STAB bits.
355 if (Data.isPrivateExtern())
356 Type |= macho::STF_PrivateExtern;
359 if (Data.isExternal() || Symbol.isUndefined())
360 Type |= macho::STF_External;
362 // Compute the symbol address.
363 if (Symbol.isDefined()) {
364 if (Symbol.isAbsolute()) {
365 Address = cast<MCConstantExpr>(Symbol.getVariableValue())->getValue();
367 Address = getSymbolAddress(&Data, Layout);
369 } else if (Data.isCommon()) {
370 // Common symbols are encoded with the size in the address
371 // field, and their alignment in the flags.
372 Address = Data.getCommonSize();
374 // Common alignment is packed into the 'desc' bits.
375 if (unsigned Align = Data.getCommonAlignment()) {
376 unsigned Log2Size = Log2_32(Align);
377 assert((1U << Log2Size) == Align && "Invalid 'common' alignment!");
379 report_fatal_error("invalid 'common' alignment '" +
381 // FIXME: Keep this mask with the SymbolFlags enumeration.
382 Flags = (Flags & 0xF0FF) | (Log2Size << 8);
386 // struct nlist (12 bytes)
388 Write32(MSD.StringIndex);
390 Write8(MSD.SectionIndex);
392 // The Mach-O streamer uses the lowest 16-bits of the flags for the 'desc'
401 // FIXME: We really need to improve the relocation validation. Basically, we
402 // want to implement a separate computation which evaluates the relocation
403 // entry as the linker would, and verifies that the resultant fixup value is
404 // exactly what the encoder wanted. This will catch several classes of
407 // - Relocation entry bugs, the two algorithms are unlikely to have the same
410 // - Relaxation issues, where we forget to relax something.
412 // - Input errors, where something cannot be correctly encoded. 'as' allows
413 // these through in many cases.
415 static bool isFixupKindRIPRel(unsigned Kind) {
416 return Kind == X86::reloc_riprel_4byte ||
417 Kind == X86::reloc_riprel_4byte_movq_load;
419 void RecordX86_64Relocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
420 const MCFragment *Fragment,
421 const MCFixup &Fixup, MCValue Target,
422 uint64_t &FixedValue) {
423 unsigned IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
424 unsigned IsRIPRel = isFixupKindRIPRel(Fixup.getKind());
425 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
428 uint32_t FixupOffset =
429 Layout.getFragmentOffset(Fragment) + Fixup.getOffset();
430 uint32_t FixupAddress =
431 getFragmentAddress(Fragment, Layout) + Fixup.getOffset();
434 unsigned IsExtern = 0;
437 Value = Target.getConstant();
440 // Compensate for the relocation offset, Darwin x86_64 relocations only
441 // have the addend and appear to have attempted to define it to be the
442 // actual expression addend without the PCrel bias. However, instructions
443 // with data following the relocation are not accomodated for (see comment
444 // below regarding SIGNED{1,2,4}), so it isn't exactly that either.
445 Value += 1LL << Log2Size;
448 if (Target.isAbsolute()) { // constant
449 // SymbolNum of 0 indicates the absolute section.
450 Type = macho::RIT_X86_64_Unsigned;
453 // FIXME: I believe this is broken, I don't think the linker can
454 // understand it. I think it would require a local relocation, but I'm not
455 // sure if that would work either. The official way to get an absolute
456 // PCrel relocation is to use an absolute symbol (which we don't support
460 Type = macho::RIT_X86_64_Branch;
462 } else if (Target.getSymB()) { // A - B + constant
463 const MCSymbol *A = &Target.getSymA()->getSymbol();
464 MCSymbolData &A_SD = Asm.getSymbolData(*A);
465 const MCSymbolData *A_Base = Asm.getAtom(&A_SD);
467 const MCSymbol *B = &Target.getSymB()->getSymbol();
468 MCSymbolData &B_SD = Asm.getSymbolData(*B);
469 const MCSymbolData *B_Base = Asm.getAtom(&B_SD);
471 // Neither symbol can be modified.
472 if (Target.getSymA()->getKind() != MCSymbolRefExpr::VK_None ||
473 Target.getSymB()->getKind() != MCSymbolRefExpr::VK_None)
474 report_fatal_error("unsupported relocation of modified symbol");
476 // We don't support PCrel relocations of differences. Darwin 'as' doesn't
477 // implement most of these correctly.
479 report_fatal_error("unsupported pc-relative relocation of difference");
481 // The support for the situation where one or both of the symbols would
482 // require a local relocation is handled just like if the symbols were
483 // external. This is certainly used in the case of debug sections where
484 // the section has only temporary symbols and thus the symbols don't have
485 // base symbols. This is encoded using the section ordinal and
486 // non-extern relocation entries.
488 // Darwin 'as' doesn't emit correct relocations for this (it ends up with
489 // a single SIGNED relocation); reject it for now. Except the case where
490 // both symbols don't have a base, equal but both NULL.
491 if (A_Base == B_Base && A_Base)
492 report_fatal_error("unsupported relocation with identical base");
494 Value += getSymbolAddress(&A_SD, Layout) -
495 (A_Base == NULL ? 0 : getSymbolAddress(A_Base, Layout));
496 Value -= getSymbolAddress(&B_SD, Layout) -
497 (B_Base == NULL ? 0 : getSymbolAddress(B_Base, Layout));
500 Index = A_Base->getIndex();
504 Index = A_SD.getFragment()->getParent()->getOrdinal() + 1;
507 Type = macho::RIT_X86_64_Unsigned;
509 macho::RelocationEntry MRE;
510 MRE.Word0 = FixupOffset;
511 MRE.Word1 = ((Index << 0) |
516 Relocations[Fragment->getParent()].push_back(MRE);
519 Index = B_Base->getIndex();
523 Index = B_SD.getFragment()->getParent()->getOrdinal() + 1;
526 Type = macho::RIT_X86_64_Subtractor;
528 const MCSymbol *Symbol = &Target.getSymA()->getSymbol();
529 MCSymbolData &SD = Asm.getSymbolData(*Symbol);
530 const MCSymbolData *Base = Asm.getAtom(&SD);
532 // Relocations inside debug sections always use local relocations when
533 // possible. This seems to be done because the debugger doesn't fully
534 // understand x86_64 relocation entries, and expects to find values that
535 // have already been fixed up.
536 if (Symbol->isInSection()) {
537 const MCSectionMachO &Section = static_cast<const MCSectionMachO&>(
538 Fragment->getParent()->getSection());
539 if (Section.hasAttribute(MCSectionMachO::S_ATTR_DEBUG))
543 // x86_64 almost always uses external relocations, except when there is no
544 // symbol to use as a base address (a local symbol with no preceeding
545 // non-local symbol).
547 Index = Base->getIndex();
550 // Add the local offset, if needed.
552 Value += Layout.getSymbolOffset(&SD) - Layout.getSymbolOffset(Base);
553 } else if (Symbol->isInSection()) {
554 // The index is the section ordinal (1-based).
555 Index = SD.getFragment()->getParent()->getOrdinal() + 1;
557 Value += getSymbolAddress(&SD, Layout);
560 Value -= FixupAddress + (1 << Log2Size);
561 } else if (Symbol->isVariable()) {
562 const MCExpr *Value = Symbol->getVariableValue();
564 bool isAbs = Value->EvaluateAsAbsolute(Res, Layout, SectionAddress);
569 report_fatal_error("unsupported relocation of variable '" +
570 Symbol->getName() + "'");
573 report_fatal_error("unsupported relocation of undefined symbol '" +
574 Symbol->getName() + "'");
577 MCSymbolRefExpr::VariantKind Modifier = Target.getSymA()->getKind();
580 if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) {
581 // x86_64 distinguishes movq foo@GOTPCREL so that the linker can
582 // rewrite the movq to an leaq at link time if the symbol ends up in
583 // the same linkage unit.
584 if (unsigned(Fixup.getKind()) == X86::reloc_riprel_4byte_movq_load)
585 Type = macho::RIT_X86_64_GOTLoad;
587 Type = macho::RIT_X86_64_GOT;
588 } else if (Modifier == MCSymbolRefExpr::VK_TLVP) {
589 Type = macho::RIT_X86_64_TLV;
590 } else if (Modifier != MCSymbolRefExpr::VK_None) {
591 report_fatal_error("unsupported symbol modifier in relocation");
593 Type = macho::RIT_X86_64_Signed;
595 // The Darwin x86_64 relocation format has a problem where it cannot
596 // encode an address (L<foo> + <constant>) which is outside the atom
597 // containing L<foo>. Generally, this shouldn't occur but it does
598 // happen when we have a RIPrel instruction with data following the
599 // relocation entry (e.g., movb $012, L0(%rip)). Even with the PCrel
600 // adjustment Darwin x86_64 uses, the offset is still negative and
601 // the linker has no way to recognize this.
603 // To work around this, Darwin uses several special relocation types
604 // to indicate the offsets. However, the specification or
605 // implementation of these seems to also be incomplete; they should
606 // adjust the addend as well based on the actual encoded instruction
607 // (the additional bias), but instead appear to just look at the
609 switch (-(Target.getConstant() + (1LL << Log2Size))) {
610 case 1: Type = macho::RIT_X86_64_Signed1; break;
611 case 2: Type = macho::RIT_X86_64_Signed2; break;
612 case 4: Type = macho::RIT_X86_64_Signed4; break;
616 if (Modifier != MCSymbolRefExpr::VK_None)
617 report_fatal_error("unsupported symbol modifier in branch "
620 Type = macho::RIT_X86_64_Branch;
623 if (Modifier == MCSymbolRefExpr::VK_GOT) {
624 Type = macho::RIT_X86_64_GOT;
625 } else if (Modifier == MCSymbolRefExpr::VK_GOTPCREL) {
626 // GOTPCREL is allowed as a modifier on non-PCrel instructions, in
627 // which case all we do is set the PCrel bit in the relocation entry;
628 // this is used with exception handling, for example. The source is
629 // required to include any necessary offset directly.
630 Type = macho::RIT_X86_64_GOT;
632 } else if (Modifier == MCSymbolRefExpr::VK_TLVP) {
633 report_fatal_error("TLVP symbol modifier should have been rip-rel");
634 } else if (Modifier != MCSymbolRefExpr::VK_None)
635 report_fatal_error("unsupported symbol modifier in relocation");
637 Type = macho::RIT_X86_64_Unsigned;
641 // x86_64 always writes custom values into the fixups.
644 // struct relocation_info (8 bytes)
645 macho::RelocationEntry MRE;
646 MRE.Word0 = FixupOffset;
647 MRE.Word1 = ((Index << 0) |
652 Relocations[Fragment->getParent()].push_back(MRE);
655 void RecordScatteredRelocation(const MCAssembler &Asm,
656 const MCAsmLayout &Layout,
657 const MCFragment *Fragment,
658 const MCFixup &Fixup, MCValue Target,
659 uint64_t &FixedValue) {
660 uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
661 unsigned IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
662 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
663 unsigned Type = macho::RIT_Vanilla;
666 const MCSymbol *A = &Target.getSymA()->getSymbol();
667 MCSymbolData *A_SD = &Asm.getSymbolData(*A);
669 if (!A_SD->getFragment())
670 report_fatal_error("symbol '" + A->getName() +
671 "' can not be undefined in a subtraction expression");
673 uint32_t Value = getSymbolAddress(A_SD, Layout);
674 uint64_t SecAddr = getSectionAddress(A_SD->getFragment()->getParent());
675 FixedValue += SecAddr;
678 if (const MCSymbolRefExpr *B = Target.getSymB()) {
679 MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
681 if (!B_SD->getFragment())
682 report_fatal_error("symbol '" + B->getSymbol().getName() +
683 "' can not be undefined in a subtraction expression");
685 // Select the appropriate difference relocation type.
687 // Note that there is no longer any semantic difference between these two
688 // relocation types from the linkers point of view, this is done solely
689 // for pedantic compatibility with 'as'.
690 Type = A_SD->isExternal() ? (unsigned)macho::RIT_Difference :
691 (unsigned)macho::RIT_Generic_LocalDifference;
692 Value2 = getSymbolAddress(B_SD, Layout);
693 FixedValue -= getSectionAddress(B_SD->getFragment()->getParent());
696 // Relocations are written out in reverse order, so the PAIR comes first.
697 if (Type == macho::RIT_Difference ||
698 Type == macho::RIT_Generic_LocalDifference) {
699 macho::RelocationEntry MRE;
700 MRE.Word0 = ((0 << 0) |
701 (macho::RIT_Pair << 24) |
704 macho::RF_Scattered);
706 Relocations[Fragment->getParent()].push_back(MRE);
709 macho::RelocationEntry MRE;
710 MRE.Word0 = ((FixupOffset << 0) |
714 macho::RF_Scattered);
716 Relocations[Fragment->getParent()].push_back(MRE);
719 void RecordARMScatteredRelocation(const MCAssembler &Asm,
720 const MCAsmLayout &Layout,
721 const MCFragment *Fragment,
722 const MCFixup &Fixup, MCValue Target,
723 uint64_t &FixedValue) {
724 uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
725 unsigned IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
726 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
727 unsigned Type = macho::RIT_Vanilla;
730 const MCSymbol *A = &Target.getSymA()->getSymbol();
731 MCSymbolData *A_SD = &Asm.getSymbolData(*A);
733 if (!A_SD->getFragment())
734 report_fatal_error("symbol '" + A->getName() +
735 "' can not be undefined in a subtraction expression");
737 uint32_t Value = getSymbolAddress(A_SD, Layout);
738 uint64_t SecAddr = getSectionAddress(A_SD->getFragment()->getParent());
739 FixedValue += SecAddr;
742 if (const MCSymbolRefExpr *B = Target.getSymB()) {
743 MCSymbolData *B_SD = &Asm.getSymbolData(B->getSymbol());
745 if (!B_SD->getFragment())
746 report_fatal_error("symbol '" + B->getSymbol().getName() +
747 "' can not be undefined in a subtraction expression");
749 // Select the appropriate difference relocation type.
750 Type = macho::RIT_Difference;
751 Value2 = getSymbolAddress(B_SD, Layout);
752 FixedValue -= getSectionAddress(B_SD->getFragment()->getParent());
755 // Relocations are written out in reverse order, so the PAIR comes first.
756 if (Type == macho::RIT_Difference ||
757 Type == macho::RIT_Generic_LocalDifference) {
758 macho::RelocationEntry MRE;
759 MRE.Word0 = ((0 << 0) |
760 (macho::RIT_Pair << 24) |
763 macho::RF_Scattered);
765 Relocations[Fragment->getParent()].push_back(MRE);
768 macho::RelocationEntry MRE;
769 MRE.Word0 = ((FixupOffset << 0) |
773 macho::RF_Scattered);
775 Relocations[Fragment->getParent()].push_back(MRE);
778 void RecordTLVPRelocation(const MCAssembler &Asm,
779 const MCAsmLayout &Layout,
780 const MCFragment *Fragment,
781 const MCFixup &Fixup, MCValue Target,
782 uint64_t &FixedValue) {
783 assert(Target.getSymA()->getKind() == MCSymbolRefExpr::VK_TLVP &&
785 "Should only be called with a 32-bit TLVP relocation!");
787 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
788 uint32_t Value = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
789 unsigned IsPCRel = 0;
791 // Get the symbol data.
792 MCSymbolData *SD_A = &Asm.getSymbolData(Target.getSymA()->getSymbol());
793 unsigned Index = SD_A->getIndex();
795 // We're only going to have a second symbol in pic mode and it'll be a
796 // subtraction from the picbase. For 32-bit pic the addend is the difference
797 // between the picbase and the next address. For 32-bit static the addend
799 if (Target.getSymB()) {
800 // If this is a subtraction then we're pcrel.
801 uint32_t FixupAddress =
802 getFragmentAddress(Fragment, Layout) + Fixup.getOffset();
803 MCSymbolData *SD_B = &Asm.getSymbolData(Target.getSymB()->getSymbol());
805 FixedValue = (FixupAddress - getSymbolAddress(SD_B, Layout) +
806 Target.getConstant());
807 FixedValue += 1ULL << Log2Size;
812 // struct relocation_info (8 bytes)
813 macho::RelocationEntry MRE;
815 MRE.Word1 = ((Index << 0) |
818 (1 << 27) | // Extern
819 (macho::RIT_Generic_TLV << 28)); // Type
820 Relocations[Fragment->getParent()].push_back(MRE);
823 static bool getARMFixupKindMachOInfo(unsigned Kind, unsigned &RelocType,
824 unsigned &Log2Size) {
825 RelocType = unsigned(macho::RIT_Vanilla);
833 Log2Size = llvm::Log2_32(1);
836 Log2Size = llvm::Log2_32(2);
839 Log2Size = llvm::Log2_32(4);
842 Log2Size = llvm::Log2_32(8);
845 // Handle 24-bit branch kinds.
846 case ARM::fixup_arm_ldst_pcrel_12:
847 case ARM::fixup_arm_pcrel_10:
848 case ARM::fixup_arm_adr_pcrel_12:
849 case ARM::fixup_arm_branch:
850 RelocType = unsigned(macho::RIT_ARM_Branch24Bit);
851 // Report as 'long', even though that is not quite accurate.
852 Log2Size = llvm::Log2_32(4);
855 // Handle Thumb branches.
856 case ARM::fixup_arm_thumb_br:
857 RelocType = unsigned(macho::RIT_ARM_ThumbBranch22Bit);
858 Log2Size = llvm::Log2_32(2);
861 case ARM::fixup_arm_thumb_bl:
862 RelocType = unsigned(macho::RIT_ARM_ThumbBranch32Bit);
863 Log2Size = llvm::Log2_32(4);
866 case ARM::fixup_arm_thumb_blx:
867 RelocType = unsigned(macho::RIT_ARM_ThumbBranch22Bit);
868 // Report as 'long', even though that is not quite accurate.
869 Log2Size = llvm::Log2_32(4);
873 void RecordARMRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
874 const MCFragment *Fragment, const MCFixup &Fixup,
875 MCValue Target, uint64_t &FixedValue) {
876 unsigned IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
878 unsigned RelocType = macho::RIT_Vanilla;
879 if (!getARMFixupKindMachOInfo(Fixup.getKind(), RelocType, Log2Size)) {
880 report_fatal_error("unknown ARM fixup kind!");
884 // If this is a difference or a defined symbol plus an offset, then we need
885 // a scattered relocation entry. Differences always require scattered
887 if (Target.getSymB())
888 return RecordARMScatteredRelocation(Asm, Layout, Fragment, Fixup,
891 // Get the symbol data, if any.
892 MCSymbolData *SD = 0;
893 if (Target.getSymA())
894 SD = &Asm.getSymbolData(Target.getSymA()->getSymbol());
896 // FIXME: For other platforms, we need to use scattered relocations for
897 // internal relocations with offsets. If this is an internal relocation
898 // with an offset, it also needs a scattered relocation entry.
900 // Is this right for ARM?
901 uint32_t Offset = Target.getConstant();
902 if (IsPCRel && RelocType == macho::RIT_Vanilla)
903 Offset += 1 << Log2Size;
904 if (Offset && SD && !doesSymbolRequireExternRelocation(SD))
905 return RecordARMScatteredRelocation(Asm, Layout, Fragment, Fixup,
909 uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
911 unsigned IsExtern = 0;
914 if (Target.isAbsolute()) { // constant
916 report_fatal_error("FIXME: relocations to absolute targets "
917 "not yet implemented");
918 } else if (SD->getSymbol().isVariable()) {
920 if (SD->getSymbol().getVariableValue()->EvaluateAsAbsolute(
921 Res, Layout, SectionAddress)) {
926 report_fatal_error("unsupported relocation of variable '" +
927 SD->getSymbol().getName() + "'");
929 // Check whether we need an external or internal relocation.
930 if (doesSymbolRequireExternRelocation(SD)) {
932 Index = SD->getIndex();
933 // For external relocations, make sure to offset the fixup value to
934 // compensate for the addend of the symbol address, if it was
935 // undefined. This occurs with weak definitions, for example.
936 if (!SD->Symbol->isUndefined())
937 FixedValue -= Layout.getSymbolOffset(SD);
939 // The index is the section ordinal (1-based).
940 Index = SD->getFragment()->getParent()->getOrdinal() + 1;
941 FixedValue += getSectionAddress(SD->getFragment()->getParent());
944 FixedValue -= getSectionAddress(Fragment->getParent());
946 // The type is determined by the fixup kind.
950 // struct relocation_info (8 bytes)
951 macho::RelocationEntry MRE;
952 MRE.Word0 = FixupOffset;
953 MRE.Word1 = ((Index << 0) |
958 Relocations[Fragment->getParent()].push_back(MRE);
961 void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
962 const MCFragment *Fragment, const MCFixup &Fixup,
963 MCValue Target, uint64_t &FixedValue) {
964 // FIXME: These needs to be factored into the target Mach-O writer.
966 RecordARMRelocation(Asm, Layout, Fragment, Fixup, Target, FixedValue);
970 RecordX86_64Relocation(Asm, Layout, Fragment, Fixup, Target, FixedValue);
974 unsigned IsPCRel = isFixupKindPCRel(Asm, Fixup.getKind());
975 unsigned Log2Size = getFixupKindLog2Size(Fixup.getKind());
977 // If this is a 32-bit TLVP reloc it's handled a bit differently.
978 if (Target.getSymA() &&
979 Target.getSymA()->getKind() == MCSymbolRefExpr::VK_TLVP) {
980 RecordTLVPRelocation(Asm, Layout, Fragment, Fixup, Target, FixedValue);
984 // If this is a difference or a defined symbol plus an offset, then we need
985 // a scattered relocation entry.
986 // Differences always require scattered relocations.
987 if (Target.getSymB())
988 return RecordScatteredRelocation(Asm, Layout, Fragment, Fixup,
991 // Get the symbol data, if any.
992 MCSymbolData *SD = 0;
993 if (Target.getSymA())
994 SD = &Asm.getSymbolData(Target.getSymA()->getSymbol());
996 // If this is an internal relocation with an offset, it also needs a
997 // scattered relocation entry.
998 uint32_t Offset = Target.getConstant();
1000 Offset += 1 << Log2Size;
1001 if (Offset && SD && !doesSymbolRequireExternRelocation(SD))
1002 return RecordScatteredRelocation(Asm, Layout, Fragment, Fixup,
1003 Target, FixedValue);
1006 uint32_t FixupOffset = Layout.getFragmentOffset(Fragment)+Fixup.getOffset();
1008 unsigned IsExtern = 0;
1011 if (Target.isAbsolute()) { // constant
1012 // SymbolNum of 0 indicates the absolute section.
1014 // FIXME: Currently, these are never generated (see code below). I cannot
1015 // find a case where they are actually emitted.
1016 Type = macho::RIT_Vanilla;
1017 } else if (SD->getSymbol().isVariable()) {
1019 if (SD->getSymbol().getVariableValue()->EvaluateAsAbsolute(
1020 Res, Layout, SectionAddress)) {
1025 report_fatal_error("unsupported relocation of variable '" +
1026 SD->getSymbol().getName() + "'");
1028 // Check whether we need an external or internal relocation.
1029 if (doesSymbolRequireExternRelocation(SD)) {
1031 Index = SD->getIndex();
1032 // For external relocations, make sure to offset the fixup value to
1033 // compensate for the addend of the symbol address, if it was
1034 // undefined. This occurs with weak definitions, for example.
1035 if (!SD->Symbol->isUndefined())
1036 FixedValue -= Layout.getSymbolOffset(SD);
1038 // The index is the section ordinal (1-based).
1039 Index = SD->getFragment()->getParent()->getOrdinal() + 1;
1040 FixedValue += getSectionAddress(SD->getFragment()->getParent());
1043 FixedValue -= getSectionAddress(Fragment->getParent());
1045 Type = macho::RIT_Vanilla;
1048 // struct relocation_info (8 bytes)
1049 macho::RelocationEntry MRE;
1050 MRE.Word0 = FixupOffset;
1051 MRE.Word1 = ((Index << 0) |
1056 Relocations[Fragment->getParent()].push_back(MRE);
1059 void BindIndirectSymbols(MCAssembler &Asm) {
1060 // This is the point where 'as' creates actual symbols for indirect symbols
1061 // (in the following two passes). It would be easier for us to do this
1062 // sooner when we see the attribute, but that makes getting the order in the
1063 // symbol table much more complicated than it is worth.
1065 // FIXME: Revisit this when the dust settles.
1067 // Bind non lazy symbol pointers first.
1068 unsigned IndirectIndex = 0;
1069 for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
1070 ie = Asm.indirect_symbol_end(); it != ie; ++it, ++IndirectIndex) {
1071 const MCSectionMachO &Section =
1072 cast<MCSectionMachO>(it->SectionData->getSection());
1074 if (Section.getType() != MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS)
1077 // Initialize the section indirect symbol base, if necessary.
1078 if (!IndirectSymBase.count(it->SectionData))
1079 IndirectSymBase[it->SectionData] = IndirectIndex;
1081 Asm.getOrCreateSymbolData(*it->Symbol);
1084 // Then lazy symbol pointers and symbol stubs.
1086 for (MCAssembler::indirect_symbol_iterator it = Asm.indirect_symbol_begin(),
1087 ie = Asm.indirect_symbol_end(); it != ie; ++it, ++IndirectIndex) {
1088 const MCSectionMachO &Section =
1089 cast<MCSectionMachO>(it->SectionData->getSection());
1091 if (Section.getType() != MCSectionMachO::S_LAZY_SYMBOL_POINTERS &&
1092 Section.getType() != MCSectionMachO::S_SYMBOL_STUBS)
1095 // Initialize the section indirect symbol base, if necessary.
1096 if (!IndirectSymBase.count(it->SectionData))
1097 IndirectSymBase[it->SectionData] = IndirectIndex;
1099 // Set the symbol type to undefined lazy, but only on construction.
1101 // FIXME: Do not hardcode.
1103 MCSymbolData &Entry = Asm.getOrCreateSymbolData(*it->Symbol, &Created);
1105 Entry.setFlags(Entry.getFlags() | 0x0001);
1109 /// ComputeSymbolTable - Compute the symbol table data
1111 /// \param StringTable [out] - The string table data.
1112 /// \param StringIndexMap [out] - Map from symbol names to offsets in the
1114 void ComputeSymbolTable(MCAssembler &Asm, SmallString<256> &StringTable,
1115 std::vector<MachSymbolData> &LocalSymbolData,
1116 std::vector<MachSymbolData> &ExternalSymbolData,
1117 std::vector<MachSymbolData> &UndefinedSymbolData) {
1118 // Build section lookup table.
1119 DenseMap<const MCSection*, uint8_t> SectionIndexMap;
1121 for (MCAssembler::iterator it = Asm.begin(),
1122 ie = Asm.end(); it != ie; ++it, ++Index)
1123 SectionIndexMap[&it->getSection()] = Index;
1124 assert(Index <= 256 && "Too many sections!");
1126 // Index 0 is always the empty string.
1127 StringMap<uint64_t> StringIndexMap;
1128 StringTable += '\x00';
1130 // Build the symbol arrays and the string table, but only for non-local
1133 // The particular order that we collect the symbols and create the string
1134 // table, then sort the symbols is chosen to match 'as'. Even though it
1135 // doesn't matter for correctness, this is important for letting us diff .o
1137 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
1138 ie = Asm.symbol_end(); it != ie; ++it) {
1139 const MCSymbol &Symbol = it->getSymbol();
1141 // Ignore non-linker visible symbols.
1142 if (!Asm.isSymbolLinkerVisible(it->getSymbol()))
1145 if (!it->isExternal() && !Symbol.isUndefined())
1148 uint64_t &Entry = StringIndexMap[Symbol.getName()];
1150 Entry = StringTable.size();
1151 StringTable += Symbol.getName();
1152 StringTable += '\x00';
1156 MSD.SymbolData = it;
1157 MSD.StringIndex = Entry;
1159 if (Symbol.isUndefined()) {
1160 MSD.SectionIndex = 0;
1161 UndefinedSymbolData.push_back(MSD);
1162 } else if (Symbol.isAbsolute()) {
1163 MSD.SectionIndex = 0;
1164 ExternalSymbolData.push_back(MSD);
1166 MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
1167 assert(MSD.SectionIndex && "Invalid section index!");
1168 ExternalSymbolData.push_back(MSD);
1172 // Now add the data for local symbols.
1173 for (MCAssembler::symbol_iterator it = Asm.symbol_begin(),
1174 ie = Asm.symbol_end(); it != ie; ++it) {
1175 const MCSymbol &Symbol = it->getSymbol();
1177 // Ignore non-linker visible symbols.
1178 if (!Asm.isSymbolLinkerVisible(it->getSymbol()))
1181 if (it->isExternal() || Symbol.isUndefined())
1184 uint64_t &Entry = StringIndexMap[Symbol.getName()];
1186 Entry = StringTable.size();
1187 StringTable += Symbol.getName();
1188 StringTable += '\x00';
1192 MSD.SymbolData = it;
1193 MSD.StringIndex = Entry;
1195 if (Symbol.isAbsolute()) {
1196 MSD.SectionIndex = 0;
1197 LocalSymbolData.push_back(MSD);
1199 MSD.SectionIndex = SectionIndexMap.lookup(&Symbol.getSection());
1200 assert(MSD.SectionIndex && "Invalid section index!");
1201 LocalSymbolData.push_back(MSD);
1205 // External and undefined symbols are required to be in lexicographic order.
1206 std::sort(ExternalSymbolData.begin(), ExternalSymbolData.end());
1207 std::sort(UndefinedSymbolData.begin(), UndefinedSymbolData.end());
1209 // Set the symbol indices.
1211 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
1212 LocalSymbolData[i].SymbolData->setIndex(Index++);
1213 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
1214 ExternalSymbolData[i].SymbolData->setIndex(Index++);
1215 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
1216 UndefinedSymbolData[i].SymbolData->setIndex(Index++);
1218 // The string table is padded to a multiple of 4.
1219 while (StringTable.size() % 4)
1220 StringTable += '\x00';
1223 void computeSectionAddresses(const MCAssembler &Asm,
1224 const MCAsmLayout &Layout) {
1225 uint64_t StartAddress = 0;
1226 const SmallVectorImpl<MCSectionData*> &Order = Layout.getSectionOrder();
1227 for (int i = 0, n = Order.size(); i != n ; ++i) {
1228 const MCSectionData *SD = Order[i];
1229 StartAddress = RoundUpToAlignment(StartAddress, SD->getAlignment());
1230 SectionAddress[SD] = StartAddress;
1231 StartAddress += Layout.getSectionAddressSize(SD);
1232 // Explicitly pad the section to match the alignment requirements of the
1233 // following one. This is for 'gas' compatibility, it shouldn't
1234 /// strictly be necessary.
1235 StartAddress += getPaddingSize(SD, Layout);
1239 void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout) {
1240 computeSectionAddresses(Asm, Layout);
1242 // Create symbol data for any indirect symbols.
1243 BindIndirectSymbols(Asm);
1245 // Compute symbol table information and bind symbol indices.
1246 ComputeSymbolTable(Asm, StringTable, LocalSymbolData, ExternalSymbolData,
1247 UndefinedSymbolData);
1250 virtual bool IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
1251 const MCSymbolData &DataA,
1252 const MCFragment &FB,
1254 bool IsPCRel) const {
1258 // The effective address is
1259 // addr(atom(A)) + offset(A)
1260 // - addr(atom(B)) - offset(B)
1261 // and the offsets are not relocatable, so the fixup is fully resolved when
1262 // addr(atom(A)) - addr(atom(B)) == 0.
1263 const MCSymbolData *A_Base = 0, *B_Base = 0;
1265 const MCSymbol &SA = DataA.getSymbol().AliasedSymbol();
1266 const MCSection &SecA = SA.getSection();
1267 const MCSection &SecB = FB.getParent()->getSection();
1270 // The simple (Darwin, except on x86_64) way of dealing with this was to
1271 // assume that any reference to a temporary symbol *must* be a temporary
1272 // symbol in the same atom, unless the sections differ. Therefore, any
1273 // PCrel relocation to a temporary symbol (in the same section) is fully
1274 // resolved. This also works in conjunction with absolutized .set, which
1275 // requires the compiler to use .set to absolutize the differences between
1276 // symbols which the compiler knows to be assembly time constants, so we
1277 // don't need to worry about considering symbol differences fully
1280 if (!Asm.getBackend().hasReliableSymbolDifference()) {
1281 if (!SA.isTemporary() || !SA.isInSection() || &SecA != &SecB)
1286 if (!TargetObjectWriter->useAggressiveSymbolFolding())
1290 const MCFragment &FA = *Asm.getSymbolData(SA).getFragment();
1292 A_Base = FA.getAtom();
1296 B_Base = FB.getAtom();
1300 // If the atoms are the same, they are guaranteed to have the same address.
1301 if (A_Base == B_Base)
1304 // Otherwise, we can't prove this is fully resolved.
1308 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout) {
1309 unsigned NumSections = Asm.size();
1311 // The section data starts after the header, the segment load command (and
1312 // section headers) and the symbol table.
1313 unsigned NumLoadCommands = 1;
1314 uint64_t LoadCommandsSize = is64Bit() ?
1315 macho::SegmentLoadCommand64Size + NumSections * macho::Section64Size :
1316 macho::SegmentLoadCommand32Size + NumSections * macho::Section32Size;
1318 // Add the symbol table load command sizes, if used.
1319 unsigned NumSymbols = LocalSymbolData.size() + ExternalSymbolData.size() +
1320 UndefinedSymbolData.size();
1322 NumLoadCommands += 2;
1323 LoadCommandsSize += (macho::SymtabLoadCommandSize +
1324 macho::DysymtabLoadCommandSize);
1327 // Compute the total size of the section data, as well as its file size and
1329 uint64_t SectionDataStart = (is64Bit() ? macho::Header64Size :
1330 macho::Header32Size) + LoadCommandsSize;
1331 uint64_t SectionDataSize = 0;
1332 uint64_t SectionDataFileSize = 0;
1333 uint64_t VMSize = 0;
1334 for (MCAssembler::const_iterator it = Asm.begin(),
1335 ie = Asm.end(); it != ie; ++it) {
1336 const MCSectionData &SD = *it;
1337 uint64_t Address = getSectionAddress(&SD);
1338 uint64_t Size = Layout.getSectionAddressSize(&SD);
1339 uint64_t FileSize = Layout.getSectionFileSize(&SD);
1340 FileSize += getPaddingSize(&SD, Layout);
1342 VMSize = std::max(VMSize, Address + Size);
1344 if (SD.getSection().isVirtualSection())
1347 SectionDataSize = std::max(SectionDataSize, Address + Size);
1348 SectionDataFileSize = std::max(SectionDataFileSize, Address + FileSize);
1351 // The section data is padded to 4 bytes.
1353 // FIXME: Is this machine dependent?
1354 unsigned SectionDataPadding = OffsetToAlignment(SectionDataFileSize, 4);
1355 SectionDataFileSize += SectionDataPadding;
1357 // Write the prolog, starting with the header and load command...
1358 WriteHeader(NumLoadCommands, LoadCommandsSize,
1359 Asm.getSubsectionsViaSymbols());
1360 WriteSegmentLoadCommand(NumSections, VMSize,
1361 SectionDataStart, SectionDataSize);
1363 // ... and then the section headers.
1364 uint64_t RelocTableEnd = SectionDataStart + SectionDataFileSize;
1365 for (MCAssembler::const_iterator it = Asm.begin(),
1366 ie = Asm.end(); it != ie; ++it) {
1367 std::vector<macho::RelocationEntry> &Relocs = Relocations[it];
1368 unsigned NumRelocs = Relocs.size();
1369 uint64_t SectionStart = SectionDataStart + getSectionAddress(it);
1370 WriteSection(Asm, Layout, *it, SectionStart, RelocTableEnd, NumRelocs);
1371 RelocTableEnd += NumRelocs * macho::RelocationInfoSize;
1374 // Write the symbol table load command, if used.
1376 unsigned FirstLocalSymbol = 0;
1377 unsigned NumLocalSymbols = LocalSymbolData.size();
1378 unsigned FirstExternalSymbol = FirstLocalSymbol + NumLocalSymbols;
1379 unsigned NumExternalSymbols = ExternalSymbolData.size();
1380 unsigned FirstUndefinedSymbol = FirstExternalSymbol + NumExternalSymbols;
1381 unsigned NumUndefinedSymbols = UndefinedSymbolData.size();
1382 unsigned NumIndirectSymbols = Asm.indirect_symbol_size();
1383 unsigned NumSymTabSymbols =
1384 NumLocalSymbols + NumExternalSymbols + NumUndefinedSymbols;
1385 uint64_t IndirectSymbolSize = NumIndirectSymbols * 4;
1386 uint64_t IndirectSymbolOffset = 0;
1388 // If used, the indirect symbols are written after the section data.
1389 if (NumIndirectSymbols)
1390 IndirectSymbolOffset = RelocTableEnd;
1392 // The symbol table is written after the indirect symbol data.
1393 uint64_t SymbolTableOffset = RelocTableEnd + IndirectSymbolSize;
1395 // The string table is written after symbol table.
1396 uint64_t StringTableOffset =
1397 SymbolTableOffset + NumSymTabSymbols * (is64Bit() ? macho::Nlist64Size :
1398 macho::Nlist32Size);
1399 WriteSymtabLoadCommand(SymbolTableOffset, NumSymTabSymbols,
1400 StringTableOffset, StringTable.size());
1402 WriteDysymtabLoadCommand(FirstLocalSymbol, NumLocalSymbols,
1403 FirstExternalSymbol, NumExternalSymbols,
1404 FirstUndefinedSymbol, NumUndefinedSymbols,
1405 IndirectSymbolOffset, NumIndirectSymbols);
1408 // Write the actual section data.
1409 for (MCAssembler::const_iterator it = Asm.begin(),
1410 ie = Asm.end(); it != ie; ++it) {
1411 Asm.WriteSectionData(it, Layout);
1413 uint64_t Pad = getPaddingSize(it, Layout);
1414 for (unsigned int i = 0; i < Pad; ++i)
1418 // Write the extra padding.
1419 WriteZeros(SectionDataPadding);
1421 // Write the relocation entries.
1422 for (MCAssembler::const_iterator it = Asm.begin(),
1423 ie = Asm.end(); it != ie; ++it) {
1424 // Write the section relocation entries, in reverse order to match 'as'
1425 // (approximately, the exact algorithm is more complicated than this).
1426 std::vector<macho::RelocationEntry> &Relocs = Relocations[it];
1427 for (unsigned i = 0, e = Relocs.size(); i != e; ++i) {
1428 Write32(Relocs[e - i - 1].Word0);
1429 Write32(Relocs[e - i - 1].Word1);
1433 // Write the symbol table data, if used.
1435 // Write the indirect symbol entries.
1436 for (MCAssembler::const_indirect_symbol_iterator
1437 it = Asm.indirect_symbol_begin(),
1438 ie = Asm.indirect_symbol_end(); it != ie; ++it) {
1439 // Indirect symbols in the non lazy symbol pointer section have some
1440 // special handling.
1441 const MCSectionMachO &Section =
1442 static_cast<const MCSectionMachO&>(it->SectionData->getSection());
1443 if (Section.getType() == MCSectionMachO::S_NON_LAZY_SYMBOL_POINTERS) {
1444 // If this symbol is defined and internal, mark it as such.
1445 if (it->Symbol->isDefined() &&
1446 !Asm.getSymbolData(*it->Symbol).isExternal()) {
1447 uint32_t Flags = macho::ISF_Local;
1448 if (it->Symbol->isAbsolute())
1449 Flags |= macho::ISF_Absolute;
1455 Write32(Asm.getSymbolData(*it->Symbol).getIndex());
1458 // FIXME: Check that offsets match computed ones.
1460 // Write the symbol table entries.
1461 for (unsigned i = 0, e = LocalSymbolData.size(); i != e; ++i)
1462 WriteNlist(LocalSymbolData[i], Layout);
1463 for (unsigned i = 0, e = ExternalSymbolData.size(); i != e; ++i)
1464 WriteNlist(ExternalSymbolData[i], Layout);
1465 for (unsigned i = 0, e = UndefinedSymbolData.size(); i != e; ++i)
1466 WriteNlist(UndefinedSymbolData[i], Layout);
1468 // Write the string table.
1469 OS << StringTable.str();
1476 MCObjectWriter *llvm::createMachObjectWriter(MCMachObjectTargetWriter *MOTW,
1478 bool IsLittleEndian) {
1479 return new MachObjectWriter(MOTW, OS, IsLittleEndian);