2 // The LLVM Compiler Infrastructure
4 // This file is distributed under the University of Illinois Open Source
5 // License. See LICENSE.TXT for details.
7 //===----------------------------------------------------------------------===//
9 #include "llvm/MC/MCStreamer.h"
11 #include "llvm/MC/MCAssembler.h"
12 #include "llvm/MC/MCContext.h"
13 #include "llvm/MC/MCCodeEmitter.h"
14 #include "llvm/MC/MCExpr.h"
15 #include "llvm/MC/MCInst.h"
16 #include "llvm/MC/MCObjectStreamer.h"
17 #include "llvm/MC/MCSection.h"
18 #include "llvm/MC/MCSymbol.h"
19 #include "llvm/MC/MCMachOSymbolFlags.h"
20 #include "llvm/MC/MCSectionMachO.h"
21 #include "llvm/MC/MCDwarf.h"
22 #include "llvm/MC/MCAsmBackend.h"
23 #include "llvm/Support/Dwarf.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Support/raw_ostream.h"
31 class MCMachOStreamer : public MCObjectStreamer {
33 virtual void EmitInstToData(const MCInst &Inst);
35 void EmitDataRegion(DataRegionData::KindTy Kind);
36 void EmitDataRegionEnd();
38 MCMachOStreamer(MCContext &Context, MCAsmBackend &MAB,
39 raw_ostream &OS, MCCodeEmitter *Emitter)
40 : MCObjectStreamer(Context, MAB, OS, Emitter) {}
42 /// @name MCStreamer Interface
45 virtual void InitSections();
46 virtual void EmitLabel(MCSymbol *Symbol);
47 virtual void EmitEHSymAttributes(const MCSymbol *Symbol,
49 virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
50 virtual void EmitDataRegion(MCDataRegionType Kind);
51 virtual void EmitThumbFunc(MCSymbol *Func);
52 virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
53 virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
54 virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
55 virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
56 unsigned ByteAlignment);
57 virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {
58 llvm_unreachable("macho doesn't support this directive");
60 virtual void EmitCOFFSymbolStorageClass(int StorageClass) {
61 llvm_unreachable("macho doesn't support this directive");
63 virtual void EmitCOFFSymbolType(int Type) {
64 llvm_unreachable("macho doesn't support this directive");
66 virtual void EndCOFFSymbolDef() {
67 llvm_unreachable("macho doesn't support this directive");
69 virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
70 llvm_unreachable("macho doesn't support this directive");
72 virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
73 unsigned ByteAlignment);
74 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
75 uint64_t 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 FinishImpl();
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::EmitDataRegion(DataRegionData::KindTy Kind) {
142 if (!getAssembler().getBackend().hasDataInCodeSupport())
144 // Create a temporary label to mark the start of the data region.
145 MCSymbol *Start = getContext().CreateTempSymbol();
147 // Record the region for the object writer to use.
148 DataRegionData Data = { Kind, Start, NULL };
149 std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
150 Regions.push_back(Data);
153 void MCMachOStreamer::EmitDataRegionEnd() {
154 if (!getAssembler().getBackend().hasDataInCodeSupport())
156 std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
157 assert(Regions.size() && "Mismatched .end_data_region!");
158 DataRegionData &Data = Regions.back();
159 assert(Data.End == NULL && "Mismatched .end_data_region!");
160 // Create a temporary label to mark the end of the data region.
161 Data.End = getContext().CreateTempSymbol();
165 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
166 // Let the target do whatever target specific stuff it needs to do.
167 getAssembler().getBackend().handleAssemblerFlag(Flag);
168 // Do any generic stuff we need to do.
170 case MCAF_SyntaxUnified: return; // no-op here.
171 case MCAF_Code16: return; // Change parsing mode; no-op here.
172 case MCAF_Code32: return; // Change parsing mode; no-op here.
173 case MCAF_Code64: return; // Change parsing mode; no-op here.
174 case MCAF_SubsectionsViaSymbols:
175 getAssembler().setSubsectionsViaSymbols(true);
180 void MCMachOStreamer::EmitDataRegion(MCDataRegionType Kind) {
182 case MCDR_DataRegion:
183 EmitDataRegion(DataRegionData::Data);
185 case MCDR_DataRegionJT8:
186 EmitDataRegion(DataRegionData::JumpTable8);
188 case MCDR_DataRegionJT16:
189 EmitDataRegion(DataRegionData::JumpTable16);
191 case MCDR_DataRegionJT32:
192 EmitDataRegion(DataRegionData::JumpTable32);
194 case MCDR_DataRegionEnd:
200 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
201 // Remember that the function is a thumb function. Fixup and relocation
202 // values will need adjusted.
203 getAssembler().setIsThumbFunc(Symbol);
205 // Mark the thumb bit on the symbol.
206 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
207 SD.setFlags(SD.getFlags() | SF_ThumbFunc);
210 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
211 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
213 // FIXME: Lift context changes into super class.
214 getAssembler().getOrCreateSymbolData(*Symbol);
215 Symbol->setVariableValue(AddValueSymbols(Value));
218 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
219 MCSymbolAttr Attribute) {
220 // Indirect symbols are handled differently, to match how 'as' handles
221 // them. This makes writing matching .o files easier.
222 if (Attribute == MCSA_IndirectSymbol) {
223 // Note that we intentionally cannot use the symbol data here; this is
224 // important for matching the string table that 'as' generates.
225 IndirectSymbolData ISD;
227 ISD.SectionData = getCurrentSectionData();
228 getAssembler().getIndirectSymbols().push_back(ISD);
232 // Adding a symbol attribute always introduces the symbol, note that an
233 // important side effect of calling getOrCreateSymbolData here is to register
234 // the symbol with the assembler.
235 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
237 // The implementation of symbol attributes is designed to match 'as', but it
238 // leaves much to desired. It doesn't really make sense to arbitrarily add and
239 // remove flags, but 'as' allows this (in particular, see .desc).
241 // In the future it might be worth trying to make these operations more well
245 case MCSA_ELF_TypeFunction:
246 case MCSA_ELF_TypeIndFunction:
247 case MCSA_ELF_TypeObject:
248 case MCSA_ELF_TypeTLS:
249 case MCSA_ELF_TypeCommon:
250 case MCSA_ELF_TypeNoType:
251 case MCSA_ELF_TypeGnuUniqueObject:
253 case MCSA_IndirectSymbol:
258 llvm_unreachable("Invalid symbol attribute for Mach-O!");
261 SD.setExternal(true);
262 // This effectively clears the undefined lazy bit, in Darwin 'as', although
263 // it isn't very consistent because it implements this as part of symbol
266 // FIXME: Cleanup this code, these bits should be emitted based on semantic
267 // properties, not on the order of definition, etc.
268 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
271 case MCSA_LazyReference:
272 // FIXME: This requires -dynamic.
273 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
274 if (Symbol->isUndefined())
275 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
278 // Since .reference sets the no dead strip bit, it is equivalent to
279 // .no_dead_strip in practice.
281 case MCSA_NoDeadStrip:
282 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
285 case MCSA_SymbolResolver:
286 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
289 case MCSA_PrivateExtern:
290 SD.setExternal(true);
291 SD.setPrivateExtern(true);
294 case MCSA_WeakReference:
295 // FIXME: This requires -dynamic.
296 if (Symbol->isUndefined())
297 SD.setFlags(SD.getFlags() | SF_WeakReference);
300 case MCSA_WeakDefinition:
301 // FIXME: 'as' enforces that this is defined and global. The manual claims
302 // it has to be in a coalesced section, but this isn't enforced.
303 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
306 case MCSA_WeakDefAutoPrivate:
307 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
312 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
313 // Encode the 'desc' value into the lowest implementation defined bits.
314 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
315 "Invalid .desc value!");
316 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
317 DescValue & SF_DescFlagsMask);
320 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
321 unsigned ByteAlignment) {
322 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
323 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
325 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
326 SD.setExternal(true);
327 SD.setCommon(Size, ByteAlignment);
330 void MCMachOStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
331 unsigned ByteAlignment) {
332 // '.lcomm' is equivalent to '.zerofill'.
333 return EmitZerofill(getContext().getMachOSection("__DATA", "__bss",
334 MCSectionMachO::S_ZEROFILL,
335 0, SectionKind::getBSS()),
336 Symbol, Size, ByteAlignment);
339 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
340 uint64_t Size, unsigned ByteAlignment) {
341 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
343 // The symbol may not be present, which only creates the section.
347 // FIXME: Assert that this section has the zerofill type.
349 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
351 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
353 // Emit an align fragment if necessary.
354 if (ByteAlignment != 1)
355 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
357 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
360 Symbol->setSection(*Section);
362 // Update the maximum alignment on the zero fill section if necessary.
363 if (ByteAlignment > SectData.getAlignment())
364 SectData.setAlignment(ByteAlignment);
367 // This should always be called with the thread local bss section. Like the
368 // .zerofill directive this doesn't actually switch sections on us.
369 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
370 uint64_t Size, unsigned ByteAlignment) {
371 EmitZerofill(Section, Symbol, Size, ByteAlignment);
375 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
376 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
378 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
381 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
382 int64_t Value, unsigned ValueSize,
383 unsigned MaxBytesToEmit) {
384 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
386 if (MaxBytesToEmit == 0)
387 MaxBytesToEmit = ByteAlignment;
388 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
389 getCurrentSectionData());
391 // Update the maximum alignment on the current section if necessary.
392 if (ByteAlignment > getCurrentSectionData()->getAlignment())
393 getCurrentSectionData()->setAlignment(ByteAlignment);
396 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
397 unsigned MaxBytesToEmit) {
398 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
400 if (MaxBytesToEmit == 0)
401 MaxBytesToEmit = ByteAlignment;
402 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
403 getCurrentSectionData());
404 F->setEmitNops(true);
406 // Update the maximum alignment on the current section if necessary.
407 if (ByteAlignment > getCurrentSectionData()->getAlignment())
408 getCurrentSectionData()->setAlignment(ByteAlignment);
411 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
412 MCDataFragment *DF = getOrCreateDataFragment();
414 SmallVector<MCFixup, 4> Fixups;
415 SmallString<256> Code;
416 raw_svector_ostream VecOS(Code);
417 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
420 // Add the fixups and data.
421 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
422 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
423 DF->addFixup(Fixups[i]);
425 DF->getContents().append(Code.begin(), Code.end());
428 void MCMachOStreamer::FinishImpl() {
431 // We have to set the fragment atom associations so we can relax properly for
434 // First, scan the symbol table to build a lookup table from fragments to
436 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
437 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
438 ie = getAssembler().symbol_end(); it != ie; ++it) {
439 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
441 // An atom defining symbol should never be internal to a fragment.
442 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
443 DefiningSymbolMap[it->getFragment()] = it;
447 // Set the fragment atom associations by tracking the last seen atom defining
449 for (MCAssembler::iterator it = getAssembler().begin(),
450 ie = getAssembler().end(); it != ie; ++it) {
451 MCSymbolData *CurrentAtom = 0;
452 for (MCSectionData::iterator it2 = it->begin(),
453 ie2 = it->end(); it2 != ie2; ++it2) {
454 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
456 it2->setAtom(CurrentAtom);
460 this->MCObjectStreamer::FinishImpl();
463 MCStreamer *llvm::createMachOStreamer(MCContext &Context, MCAsmBackend &MAB,
464 raw_ostream &OS, MCCodeEmitter *CE,
466 MCMachOStreamer *S = new MCMachOStreamer(Context, MAB, OS, CE);
468 S->getAssembler().setRelaxAll(true);