1 //===-- MCMachOStreamer.cpp - MachO Streamer ------------------------------===//
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"
11 #include "llvm/MC/MCAsmBackend.h"
12 #include "llvm/MC/MCAssembler.h"
13 #include "llvm/MC/MCCodeEmitter.h"
14 #include "llvm/MC/MCContext.h"
15 #include "llvm/MC/MCDwarf.h"
16 #include "llvm/MC/MCExpr.h"
17 #include "llvm/MC/MCInst.h"
18 #include "llvm/MC/MCMachOSymbolFlags.h"
19 #include "llvm/MC/MCObjectFileInfo.h"
20 #include "llvm/MC/MCObjectStreamer.h"
21 #include "llvm/MC/MCSection.h"
22 #include "llvm/MC/MCSectionMachO.h"
23 #include "llvm/MC/MCSymbol.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, const MCSubtargetInfo &STI);
36 void EmitDataRegion(DataRegionData::KindTy Kind);
37 void EmitDataRegionEnd();
39 MCMachOStreamer(MCContext &Context, MCAsmBackend &MAB, raw_ostream &OS,
40 MCCodeEmitter *Emitter)
41 : MCObjectStreamer(Context, MAB, OS, Emitter) {}
43 /// @name MCStreamer Interface
46 virtual void EmitLabel(MCSymbol *Symbol);
47 virtual void EmitDebugLabel(MCSymbol *Symbol);
48 virtual void EmitEHSymAttributes(const MCSymbol *Symbol,
50 virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
51 virtual void EmitLinkerOptions(ArrayRef<std::string> Options);
52 virtual void EmitDataRegion(MCDataRegionType Kind);
53 virtual void EmitThumbFunc(MCSymbol *Func);
54 virtual bool EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
55 virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
56 virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
57 unsigned ByteAlignment);
58 virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {
59 llvm_unreachable("macho doesn't support this directive");
61 virtual void EmitCOFFSymbolStorageClass(int StorageClass) {
62 llvm_unreachable("macho doesn't support this directive");
64 virtual void EmitCOFFSymbolType(int Type) {
65 llvm_unreachable("macho doesn't support this directive");
67 virtual void EndCOFFSymbolDef() {
68 llvm_unreachable("macho doesn't support this directive");
70 virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
71 llvm_unreachable("macho doesn't support this directive");
73 virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
74 unsigned ByteAlignment);
75 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
76 uint64_t Size = 0, unsigned ByteAlignment = 0);
77 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
78 uint64_t Size, unsigned ByteAlignment = 0);
80 virtual void EmitFileDirective(StringRef Filename) {
81 // FIXME: Just ignore the .file; it isn't important enough to fail the
84 // report_fatal_error("unsupported directive: '.file'");
87 virtual void EmitIdent(StringRef IdentString) {
88 llvm_unreachable("macho doesn't support this directive");
91 virtual void FinishImpl();
94 } // end anonymous namespace.
96 void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
99 getAssembler().getOrCreateSymbolData(*Symbol);
101 EmitSymbolAttribute(EHSymbol, MCSA_Global);
102 if (SD.getFlags() & SF_WeakDefinition)
103 EmitSymbolAttribute(EHSymbol, MCSA_WeakDefinition);
104 if (SD.isPrivateExtern())
105 EmitSymbolAttribute(EHSymbol, MCSA_PrivateExtern);
108 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
109 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
111 // isSymbolLinkerVisible uses the section.
112 AssignSection(Symbol, getCurrentSection().first);
113 // We have to create a new fragment if this is an atom defining symbol,
114 // fragments cannot span atoms.
115 if (getAssembler().isSymbolLinkerVisible(*Symbol))
116 insert(new MCDataFragment());
118 MCObjectStreamer::EmitLabel(Symbol);
120 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
121 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
122 // to clear the weak reference and weak definition bits too, but the
123 // implementation was buggy. For now we just try to match 'as', for
126 // FIXME: Cleanup this code, these bits should be emitted based on semantic
127 // properties, not on the order of definition, etc.
128 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
131 void MCMachOStreamer::EmitDebugLabel(MCSymbol *Symbol) {
134 void MCMachOStreamer::EmitDataRegion(DataRegionData::KindTy Kind) {
135 if (!getAssembler().getBackend().hasDataInCodeSupport())
137 // Create a temporary label to mark the start of the data region.
138 MCSymbol *Start = getContext().CreateTempSymbol();
140 // Record the region for the object writer to use.
141 DataRegionData Data = { Kind, Start, NULL };
142 std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
143 Regions.push_back(Data);
146 void MCMachOStreamer::EmitDataRegionEnd() {
147 if (!getAssembler().getBackend().hasDataInCodeSupport())
149 std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
150 assert(Regions.size() && "Mismatched .end_data_region!");
151 DataRegionData &Data = Regions.back();
152 assert(Data.End == NULL && "Mismatched .end_data_region!");
153 // Create a temporary label to mark the end of the data region.
154 Data.End = getContext().CreateTempSymbol();
158 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
159 // Let the target do whatever target specific stuff it needs to do.
160 getAssembler().getBackend().handleAssemblerFlag(Flag);
161 // Do any generic stuff we need to do.
163 case MCAF_SyntaxUnified: return; // no-op here.
164 case MCAF_Code16: return; // Change parsing mode; no-op here.
165 case MCAF_Code32: return; // Change parsing mode; no-op here.
166 case MCAF_Code64: return; // Change parsing mode; no-op here.
167 case MCAF_SubsectionsViaSymbols:
168 getAssembler().setSubsectionsViaSymbols(true);
173 void MCMachOStreamer::EmitLinkerOptions(ArrayRef<std::string> Options) {
174 getAssembler().getLinkerOptions().push_back(Options);
177 void MCMachOStreamer::EmitDataRegion(MCDataRegionType Kind) {
179 case MCDR_DataRegion:
180 EmitDataRegion(DataRegionData::Data);
182 case MCDR_DataRegionJT8:
183 EmitDataRegion(DataRegionData::JumpTable8);
185 case MCDR_DataRegionJT16:
186 EmitDataRegion(DataRegionData::JumpTable16);
188 case MCDR_DataRegionJT32:
189 EmitDataRegion(DataRegionData::JumpTable32);
191 case MCDR_DataRegionEnd:
197 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
198 // Remember that the function is a thumb function. Fixup and relocation
199 // values will need adjusted.
200 getAssembler().setIsThumbFunc(Symbol);
202 // Mark the thumb bit on the symbol.
203 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
204 SD.setFlags(SD.getFlags() | SF_ThumbFunc);
207 bool MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
208 MCSymbolAttr Attribute) {
209 // Indirect symbols are handled differently, to match how 'as' handles
210 // them. This makes writing matching .o files easier.
211 if (Attribute == MCSA_IndirectSymbol) {
212 // Note that we intentionally cannot use the symbol data here; this is
213 // important for matching the string table that 'as' generates.
214 IndirectSymbolData ISD;
216 ISD.SectionData = getCurrentSectionData();
217 getAssembler().getIndirectSymbols().push_back(ISD);
221 // Adding a symbol attribute always introduces the symbol, note that an
222 // important side effect of calling getOrCreateSymbolData here is to register
223 // the symbol with the assembler.
224 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
226 // The implementation of symbol attributes is designed to match 'as', but it
227 // leaves much to desired. It doesn't really make sense to arbitrarily add and
228 // remove flags, but 'as' allows this (in particular, see .desc).
230 // In the future it might be worth trying to make these operations more well
234 case MCSA_ELF_TypeFunction:
235 case MCSA_ELF_TypeIndFunction:
236 case MCSA_ELF_TypeObject:
237 case MCSA_ELF_TypeTLS:
238 case MCSA_ELF_TypeCommon:
239 case MCSA_ELF_TypeNoType:
240 case MCSA_ELF_TypeGnuUniqueObject:
242 case MCSA_IndirectSymbol:
250 SD.setExternal(true);
251 // This effectively clears the undefined lazy bit, in Darwin 'as', although
252 // it isn't very consistent because it implements this as part of symbol
255 // FIXME: Cleanup this code, these bits should be emitted based on semantic
256 // properties, not on the order of definition, etc.
257 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
260 case MCSA_LazyReference:
261 // FIXME: This requires -dynamic.
262 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
263 if (Symbol->isUndefined())
264 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
267 // Since .reference sets the no dead strip bit, it is equivalent to
268 // .no_dead_strip in practice.
270 case MCSA_NoDeadStrip:
271 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
274 case MCSA_SymbolResolver:
275 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
278 case MCSA_PrivateExtern:
279 SD.setExternal(true);
280 SD.setPrivateExtern(true);
283 case MCSA_WeakReference:
284 // FIXME: This requires -dynamic.
285 if (Symbol->isUndefined())
286 SD.setFlags(SD.getFlags() | SF_WeakReference);
289 case MCSA_WeakDefinition:
290 // FIXME: 'as' enforces that this is defined and global. The manual claims
291 // it has to be in a coalesced section, but this isn't enforced.
292 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
295 case MCSA_WeakDefAutoPrivate:
296 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
303 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
304 // Encode the 'desc' value into the lowest implementation defined bits.
305 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
306 "Invalid .desc value!");
307 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
308 DescValue & SF_DescFlagsMask);
311 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
312 unsigned ByteAlignment) {
313 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
314 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
316 AssignSection(Symbol, NULL);
318 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
319 SD.setExternal(true);
320 SD.setCommon(Size, ByteAlignment);
323 void MCMachOStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
324 unsigned ByteAlignment) {
325 // '.lcomm' is equivalent to '.zerofill'.
326 return EmitZerofill(getContext().getObjectFileInfo()->getDataBSSSection(),
327 Symbol, Size, ByteAlignment);
330 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
331 uint64_t Size, unsigned ByteAlignment) {
332 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
334 // The symbol may not be present, which only creates the section.
338 // On darwin all virtual sections have zerofill type.
339 assert(Section->isVirtualSection() && "Section does not have zerofill type!");
341 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
343 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
345 // Emit an align fragment if necessary.
346 if (ByteAlignment != 1)
347 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
349 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
352 AssignSection(Symbol, Section);
354 // Update the maximum alignment on the zero fill section if necessary.
355 if (ByteAlignment > SectData.getAlignment())
356 SectData.setAlignment(ByteAlignment);
359 // This should always be called with the thread local bss section. Like the
360 // .zerofill directive this doesn't actually switch sections on us.
361 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
362 uint64_t Size, unsigned ByteAlignment) {
363 EmitZerofill(Section, Symbol, Size, ByteAlignment);
367 void MCMachOStreamer::EmitInstToData(const MCInst &Inst,
368 const MCSubtargetInfo &STI) {
369 MCDataFragment *DF = getOrCreateDataFragment();
371 SmallVector<MCFixup, 4> Fixups;
372 SmallString<256> Code;
373 raw_svector_ostream VecOS(Code);
374 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups, STI);
377 // Add the fixups and data.
378 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
379 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
380 DF->getFixups().push_back(Fixups[i]);
382 DF->getContents().append(Code.begin(), Code.end());
385 void MCMachOStreamer::FinishImpl() {
386 EmitFrames(&getAssembler().getBackend(), true);
388 // We have to set the fragment atom associations so we can relax properly for
391 // First, scan the symbol table to build a lookup table from fragments to
393 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
394 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
395 ie = getAssembler().symbol_end(); it != ie; ++it) {
396 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
398 // An atom defining symbol should never be internal to a fragment.
399 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
400 DefiningSymbolMap[it->getFragment()] = it;
404 // Set the fragment atom associations by tracking the last seen atom defining
406 for (MCAssembler::iterator it = getAssembler().begin(),
407 ie = getAssembler().end(); it != ie; ++it) {
408 MCSymbolData *CurrentAtom = 0;
409 for (MCSectionData::iterator it2 = it->begin(),
410 ie2 = it->end(); it2 != ie2; ++it2) {
411 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
413 it2->setAtom(CurrentAtom);
417 this->MCObjectStreamer::FinishImpl();
420 MCStreamer *llvm::createMachOStreamer(MCContext &Context, MCAsmBackend &MAB,
421 raw_ostream &OS, MCCodeEmitter *CE,
423 MCMachOStreamer *S = new MCMachOStreamer(Context, MAB, OS, CE);
425 S->getAssembler().setRelaxAll(true);