1 //===- lib/MC/MCMachOStreamer.cpp - Mach-O Object Output ------------===//
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/MCStreamer.h"
12 #include "llvm/MC/MCAssembler.h"
13 #include "llvm/MC/MCContext.h"
14 #include "llvm/MC/MCCodeEmitter.h"
15 #include "llvm/MC/MCExpr.h"
16 #include "llvm/MC/MCInst.h"
17 #include "llvm/MC/MCObjectStreamer.h"
18 #include "llvm/MC/MCSection.h"
19 #include "llvm/MC/MCSymbol.h"
20 #include "llvm/MC/MCMachOSymbolFlags.h"
21 #include "llvm/MC/MCSectionMachO.h"
22 #include "llvm/MC/MCDwarf.h"
23 #include "llvm/MC/MCAsmBackend.h"
24 #include "llvm/Support/Dwarf.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/raw_ostream.h"
32 class MCMachOStreamer : public MCObjectStreamer {
34 virtual void EmitInstToData(const MCInst &Inst);
37 MCMachOStreamer(MCContext &Context, MCAsmBackend &MAB,
38 raw_ostream &OS, MCCodeEmitter *Emitter)
39 : MCObjectStreamer(Context, MAB, OS, Emitter) {}
41 /// @name MCStreamer Interface
44 virtual void InitSections();
45 virtual void EmitLabel(MCSymbol *Symbol);
46 virtual void EmitEHSymAttributes(const MCSymbol *Symbol,
48 virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
49 virtual void EmitThumbFunc(MCSymbol *Func);
50 virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
51 virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
52 virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
53 virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
54 unsigned ByteAlignment);
55 virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {
56 assert(0 && "macho doesn't support this directive");
58 virtual void EmitCOFFSymbolStorageClass(int StorageClass) {
59 assert(0 && "macho doesn't support this directive");
61 virtual void EmitCOFFSymbolType(int Type) {
62 assert(0 && "macho doesn't support this directive");
64 virtual void EndCOFFSymbolDef() {
65 assert(0 && "macho doesn't support this directive");
67 virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
68 assert(0 && "macho doesn't support this directive");
70 virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
71 unsigned ByteAlignment) {
72 assert(0 && "macho doesn't support this directive");
74 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
75 unsigned Size = 0, unsigned ByteAlignment = 0);
76 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
77 uint64_t Size, unsigned ByteAlignment = 0);
78 virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
79 virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
80 unsigned ValueSize = 1,
81 unsigned MaxBytesToEmit = 0);
82 virtual void EmitCodeAlignment(unsigned ByteAlignment,
83 unsigned MaxBytesToEmit = 0);
85 virtual void EmitFileDirective(StringRef Filename) {
86 // FIXME: Just ignore the .file; it isn't important enough to fail the
89 //report_fatal_error("unsupported directive: '.file'");
92 virtual void Finish();
97 } // end anonymous namespace.
99 void MCMachOStreamer::InitSections() {
100 SwitchSection(getContext().getMachOSection("__TEXT", "__text",
101 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
102 0, SectionKind::getText()));
106 void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
107 MCSymbol *EHSymbol) {
109 getAssembler().getOrCreateSymbolData(*Symbol);
111 EmitSymbolAttribute(EHSymbol, MCSA_Global);
112 if (SD.getFlags() & SF_WeakDefinition)
113 EmitSymbolAttribute(EHSymbol, MCSA_WeakDefinition);
114 if (SD.isPrivateExtern())
115 EmitSymbolAttribute(EHSymbol, MCSA_PrivateExtern);
118 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
119 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
121 // isSymbolLinkerVisible uses the section.
122 Symbol->setSection(*getCurrentSection());
123 // We have to create a new fragment if this is an atom defining symbol,
124 // fragments cannot span atoms.
125 if (getAssembler().isSymbolLinkerVisible(*Symbol))
126 new MCDataFragment(getCurrentSectionData());
128 MCObjectStreamer::EmitLabel(Symbol);
130 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
131 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
132 // to clear the weak reference and weak definition bits too, but the
133 // implementation was buggy. For now we just try to match 'as', for
136 // FIXME: Cleanup this code, these bits should be emitted based on semantic
137 // properties, not on the order of definition, etc.
138 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
141 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
142 // Let the target do whatever target specific stuff it needs to do.
143 getAssembler().getBackend().HandleAssemblerFlag(Flag);
144 // Do any generic stuff we need to do.
146 case MCAF_SyntaxUnified: return; // no-op here.
147 case MCAF_Code16: return; // Change parsing mode; no-op here.
148 case MCAF_Code32: return; // Change parsing mode; no-op here.
149 case MCAF_Code64: return; // Change parsing mode; no-op here.
150 case MCAF_SubsectionsViaSymbols:
151 getAssembler().setSubsectionsViaSymbols(true);
154 llvm_unreachable("invalid assembler flag!");
158 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
159 // FIXME: Flag the function ISA as thumb with DW_AT_APPLE_isa.
161 // Remember that the function is a thumb function. Fixup and relocation
162 // values will need adjusted.
163 getAssembler().setIsThumbFunc(Symbol);
165 // Mark the thumb bit on the symbol.
166 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
167 SD.setFlags(SD.getFlags() | SF_ThumbFunc);
170 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
171 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
173 // FIXME: Lift context changes into super class.
174 getAssembler().getOrCreateSymbolData(*Symbol);
175 Symbol->setVariableValue(AddValueSymbols(Value));
178 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
179 MCSymbolAttr Attribute) {
180 // Indirect symbols are handled differently, to match how 'as' handles
181 // them. This makes writing matching .o files easier.
182 if (Attribute == MCSA_IndirectSymbol) {
183 // Note that we intentionally cannot use the symbol data here; this is
184 // important for matching the string table that 'as' generates.
185 IndirectSymbolData ISD;
187 ISD.SectionData = getCurrentSectionData();
188 getAssembler().getIndirectSymbols().push_back(ISD);
192 // Adding a symbol attribute always introduces the symbol, note that an
193 // important side effect of calling getOrCreateSymbolData here is to register
194 // the symbol with the assembler.
195 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
197 // The implementation of symbol attributes is designed to match 'as', but it
198 // leaves much to desired. It doesn't really make sense to arbitrarily add and
199 // remove flags, but 'as' allows this (in particular, see .desc).
201 // In the future it might be worth trying to make these operations more well
205 case MCSA_ELF_TypeFunction:
206 case MCSA_ELF_TypeIndFunction:
207 case MCSA_ELF_TypeObject:
208 case MCSA_ELF_TypeTLS:
209 case MCSA_ELF_TypeCommon:
210 case MCSA_ELF_TypeNoType:
211 case MCSA_ELF_TypeGnuUniqueObject:
213 case MCSA_IndirectSymbol:
218 assert(0 && "Invalid symbol attribute for Mach-O!");
222 SD.setExternal(true);
223 // This effectively clears the undefined lazy bit, in Darwin 'as', although
224 // it isn't very consistent because it implements this as part of symbol
227 // FIXME: Cleanup this code, these bits should be emitted based on semantic
228 // properties, not on the order of definition, etc.
229 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
232 case MCSA_LazyReference:
233 // FIXME: This requires -dynamic.
234 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
235 if (Symbol->isUndefined())
236 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
239 // Since .reference sets the no dead strip bit, it is equivalent to
240 // .no_dead_strip in practice.
242 case MCSA_NoDeadStrip:
243 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
246 case MCSA_SymbolResolver:
247 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
250 case MCSA_PrivateExtern:
251 SD.setExternal(true);
252 SD.setPrivateExtern(true);
255 case MCSA_WeakReference:
256 // FIXME: This requires -dynamic.
257 if (Symbol->isUndefined())
258 SD.setFlags(SD.getFlags() | SF_WeakReference);
261 case MCSA_WeakDefinition:
262 // FIXME: 'as' enforces that this is defined and global. The manual claims
263 // it has to be in a coalesced section, but this isn't enforced.
264 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
267 case MCSA_WeakDefAutoPrivate:
268 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
273 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
274 // Encode the 'desc' value into the lowest implementation defined bits.
275 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
276 "Invalid .desc value!");
277 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
278 DescValue & SF_DescFlagsMask);
281 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
282 unsigned ByteAlignment) {
283 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
284 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
286 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
287 SD.setExternal(true);
288 SD.setCommon(Size, ByteAlignment);
291 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
292 unsigned Size, unsigned ByteAlignment) {
293 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
295 // The symbol may not be present, which only creates the section.
299 // FIXME: Assert that this section has the zerofill type.
301 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
303 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
305 // Emit an align fragment if necessary.
306 if (ByteAlignment != 1)
307 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
309 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
312 Symbol->setSection(*Section);
314 // Update the maximum alignment on the zero fill section if necessary.
315 if (ByteAlignment > SectData.getAlignment())
316 SectData.setAlignment(ByteAlignment);
319 // This should always be called with the thread local bss section. Like the
320 // .zerofill directive this doesn't actually switch sections on us.
321 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
322 uint64_t Size, unsigned ByteAlignment) {
323 EmitZerofill(Section, Symbol, Size, ByteAlignment);
327 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
328 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
330 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
333 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
334 int64_t Value, unsigned ValueSize,
335 unsigned MaxBytesToEmit) {
336 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
338 if (MaxBytesToEmit == 0)
339 MaxBytesToEmit = ByteAlignment;
340 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
341 getCurrentSectionData());
343 // Update the maximum alignment on the current section if necessary.
344 if (ByteAlignment > getCurrentSectionData()->getAlignment())
345 getCurrentSectionData()->setAlignment(ByteAlignment);
348 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
349 unsigned MaxBytesToEmit) {
350 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
352 if (MaxBytesToEmit == 0)
353 MaxBytesToEmit = ByteAlignment;
354 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
355 getCurrentSectionData());
356 F->setEmitNops(true);
358 // Update the maximum alignment on the current section if necessary.
359 if (ByteAlignment > getCurrentSectionData()->getAlignment())
360 getCurrentSectionData()->setAlignment(ByteAlignment);
363 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
364 MCDataFragment *DF = getOrCreateDataFragment();
366 SmallVector<MCFixup, 4> Fixups;
367 SmallString<256> Code;
368 raw_svector_ostream VecOS(Code);
369 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
372 // Add the fixups and data.
373 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
374 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
375 DF->addFixup(Fixups[i]);
377 DF->getContents().append(Code.begin(), Code.end());
380 void MCMachOStreamer::Finish() {
383 // We have to set the fragment atom associations so we can relax properly for
386 // First, scan the symbol table to build a lookup table from fragments to
388 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
389 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
390 ie = getAssembler().symbol_end(); it != ie; ++it) {
391 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
393 // An atom defining symbol should never be internal to a fragment.
394 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
395 DefiningSymbolMap[it->getFragment()] = it;
399 // Set the fragment atom associations by tracking the last seen atom defining
401 for (MCAssembler::iterator it = getAssembler().begin(),
402 ie = getAssembler().end(); it != ie; ++it) {
403 MCSymbolData *CurrentAtom = 0;
404 for (MCSectionData::iterator it2 = it->begin(),
405 ie2 = it->end(); it2 != ie2; ++it2) {
406 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
408 it2->setAtom(CurrentAtom);
412 this->MCObjectStreamer::Finish();
415 MCStreamer *llvm::createMachOStreamer(MCContext &Context, MCAsmBackend &MAB,
416 raw_ostream &OS, MCCodeEmitter *CE,
418 MCMachOStreamer *S = new MCMachOStreamer(Context, MAB, OS, CE);
420 S->getAssembler().setRelaxAll(true);