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);
79 virtual void EmitFileDirective(StringRef Filename) {
80 // FIXME: Just ignore the .file; it isn't important enough to fail the
83 //report_fatal_error("unsupported directive: '.file'");
86 virtual void FinishImpl();
91 } // end anonymous namespace.
93 void MCMachOStreamer::InitSections() {
94 SwitchSection(getContext().getMachOSection("__TEXT", "__text",
95 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
96 0, SectionKind::getText()));
100 void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
101 MCSymbol *EHSymbol) {
103 getAssembler().getOrCreateSymbolData(*Symbol);
105 EmitSymbolAttribute(EHSymbol, MCSA_Global);
106 if (SD.getFlags() & SF_WeakDefinition)
107 EmitSymbolAttribute(EHSymbol, MCSA_WeakDefinition);
108 if (SD.isPrivateExtern())
109 EmitSymbolAttribute(EHSymbol, MCSA_PrivateExtern);
112 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
113 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
115 // isSymbolLinkerVisible uses the section.
116 Symbol->setSection(*getCurrentSection());
117 // We have to create a new fragment if this is an atom defining symbol,
118 // fragments cannot span atoms.
119 if (getAssembler().isSymbolLinkerVisible(*Symbol))
120 new MCDataFragment(getCurrentSectionData());
122 MCObjectStreamer::EmitLabel(Symbol);
124 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
125 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
126 // to clear the weak reference and weak definition bits too, but the
127 // implementation was buggy. For now we just try to match 'as', for
130 // FIXME: Cleanup this code, these bits should be emitted based on semantic
131 // properties, not on the order of definition, etc.
132 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
135 void MCMachOStreamer::EmitDataRegion(DataRegionData::KindTy Kind) {
136 if (!getAssembler().getBackend().hasDataInCodeSupport())
138 // Create a temporary label to mark the start of the data region.
139 MCSymbol *Start = getContext().CreateTempSymbol();
141 // Record the region for the object writer to use.
142 DataRegionData Data = { Kind, Start, NULL };
143 std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
144 Regions.push_back(Data);
147 void MCMachOStreamer::EmitDataRegionEnd() {
148 if (!getAssembler().getBackend().hasDataInCodeSupport())
150 std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
151 assert(Regions.size() && "Mismatched .end_data_region!");
152 DataRegionData &Data = Regions.back();
153 assert(Data.End == NULL && "Mismatched .end_data_region!");
154 // Create a temporary label to mark the end of the data region.
155 Data.End = getContext().CreateTempSymbol();
159 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
160 // Let the target do whatever target specific stuff it needs to do.
161 getAssembler().getBackend().handleAssemblerFlag(Flag);
162 // Do any generic stuff we need to do.
164 case MCAF_SyntaxUnified: return; // no-op here.
165 case MCAF_Code16: return; // Change parsing mode; no-op here.
166 case MCAF_Code32: return; // Change parsing mode; no-op here.
167 case MCAF_Code64: return; // Change parsing mode; no-op here.
168 case MCAF_SubsectionsViaSymbols:
169 getAssembler().setSubsectionsViaSymbols(true);
174 void MCMachOStreamer::EmitDataRegion(MCDataRegionType Kind) {
176 case MCDR_DataRegion:
177 EmitDataRegion(DataRegionData::Data);
179 case MCDR_DataRegionJT8:
180 EmitDataRegion(DataRegionData::JumpTable8);
182 case MCDR_DataRegionJT16:
183 EmitDataRegion(DataRegionData::JumpTable16);
185 case MCDR_DataRegionJT32:
186 EmitDataRegion(DataRegionData::JumpTable32);
188 case MCDR_DataRegionEnd:
194 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
195 // Remember that the function is a thumb function. Fixup and relocation
196 // values will need adjusted.
197 getAssembler().setIsThumbFunc(Symbol);
199 // Mark the thumb bit on the symbol.
200 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
201 SD.setFlags(SD.getFlags() | SF_ThumbFunc);
204 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
205 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
207 // FIXME: Lift context changes into super class.
208 getAssembler().getOrCreateSymbolData(*Symbol);
209 Symbol->setVariableValue(AddValueSymbols(Value));
212 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
213 MCSymbolAttr Attribute) {
214 // Indirect symbols are handled differently, to match how 'as' handles
215 // them. This makes writing matching .o files easier.
216 if (Attribute == MCSA_IndirectSymbol) {
217 // Note that we intentionally cannot use the symbol data here; this is
218 // important for matching the string table that 'as' generates.
219 IndirectSymbolData ISD;
221 ISD.SectionData = getCurrentSectionData();
222 getAssembler().getIndirectSymbols().push_back(ISD);
226 // Adding a symbol attribute always introduces the symbol, note that an
227 // important side effect of calling getOrCreateSymbolData here is to register
228 // the symbol with the assembler.
229 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
231 // The implementation of symbol attributes is designed to match 'as', but it
232 // leaves much to desired. It doesn't really make sense to arbitrarily add and
233 // remove flags, but 'as' allows this (in particular, see .desc).
235 // In the future it might be worth trying to make these operations more well
239 case MCSA_ELF_TypeFunction:
240 case MCSA_ELF_TypeIndFunction:
241 case MCSA_ELF_TypeObject:
242 case MCSA_ELF_TypeTLS:
243 case MCSA_ELF_TypeCommon:
244 case MCSA_ELF_TypeNoType:
245 case MCSA_ELF_TypeGnuUniqueObject:
247 case MCSA_IndirectSymbol:
252 llvm_unreachable("Invalid symbol attribute for Mach-O!");
255 SD.setExternal(true);
256 // This effectively clears the undefined lazy bit, in Darwin 'as', although
257 // it isn't very consistent because it implements this as part of symbol
260 // FIXME: Cleanup this code, these bits should be emitted based on semantic
261 // properties, not on the order of definition, etc.
262 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
265 case MCSA_LazyReference:
266 // FIXME: This requires -dynamic.
267 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
268 if (Symbol->isUndefined())
269 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
272 // Since .reference sets the no dead strip bit, it is equivalent to
273 // .no_dead_strip in practice.
275 case MCSA_NoDeadStrip:
276 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
279 case MCSA_SymbolResolver:
280 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
283 case MCSA_PrivateExtern:
284 SD.setExternal(true);
285 SD.setPrivateExtern(true);
288 case MCSA_WeakReference:
289 // FIXME: This requires -dynamic.
290 if (Symbol->isUndefined())
291 SD.setFlags(SD.getFlags() | SF_WeakReference);
294 case MCSA_WeakDefinition:
295 // FIXME: 'as' enforces that this is defined and global. The manual claims
296 // it has to be in a coalesced section, but this isn't enforced.
297 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
300 case MCSA_WeakDefAutoPrivate:
301 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
306 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
307 // Encode the 'desc' value into the lowest implementation defined bits.
308 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
309 "Invalid .desc value!");
310 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
311 DescValue & SF_DescFlagsMask);
314 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
315 unsigned ByteAlignment) {
316 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
317 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
319 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
320 SD.setExternal(true);
321 SD.setCommon(Size, ByteAlignment);
324 void MCMachOStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
325 unsigned ByteAlignment) {
326 // '.lcomm' is equivalent to '.zerofill'.
327 return EmitZerofill(getContext().getMachOSection("__DATA", "__bss",
328 MCSectionMachO::S_ZEROFILL,
329 0, SectionKind::getBSS()),
330 Symbol, Size, ByteAlignment);
333 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
334 uint64_t Size, unsigned ByteAlignment) {
335 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
337 // The symbol may not be present, which only creates the section.
341 // FIXME: Assert that this section has the zerofill type.
343 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
345 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
347 // Emit an align fragment if necessary.
348 if (ByteAlignment != 1)
349 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
351 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
354 Symbol->setSection(*Section);
356 // Update the maximum alignment on the zero fill section if necessary.
357 if (ByteAlignment > SectData.getAlignment())
358 SectData.setAlignment(ByteAlignment);
361 // This should always be called with the thread local bss section. Like the
362 // .zerofill directive this doesn't actually switch sections on us.
363 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
364 uint64_t Size, unsigned ByteAlignment) {
365 EmitZerofill(Section, Symbol, Size, ByteAlignment);
369 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
370 MCDataFragment *DF = getOrCreateDataFragment();
372 SmallVector<MCFixup, 4> Fixups;
373 SmallString<256> Code;
374 raw_svector_ostream VecOS(Code);
375 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
378 // Add the fixups and data.
379 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
380 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
381 DF->addFixup(Fixups[i]);
383 DF->getContents().append(Code.begin(), Code.end());
386 void MCMachOStreamer::FinishImpl() {
389 // We have to set the fragment atom associations so we can relax properly for
392 // First, scan the symbol table to build a lookup table from fragments to
394 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
395 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
396 ie = getAssembler().symbol_end(); it != ie; ++it) {
397 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
399 // An atom defining symbol should never be internal to a fragment.
400 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
401 DefiningSymbolMap[it->getFragment()] = it;
405 // Set the fragment atom associations by tracking the last seen atom defining
407 for (MCAssembler::iterator it = getAssembler().begin(),
408 ie = getAssembler().end(); it != ie; ++it) {
409 MCSymbolData *CurrentAtom = 0;
410 for (MCSectionData::iterator it2 = it->begin(),
411 ie2 = it->end(); it2 != ie2; ++it2) {
412 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
414 it2->setAtom(CurrentAtom);
418 this->MCObjectStreamer::FinishImpl();
421 MCStreamer *llvm::createMachOStreamer(MCContext &Context, MCAsmBackend &MAB,
422 raw_ostream &OS, MCCodeEmitter *CE,
424 MCMachOStreamer *S = new MCMachOStreamer(Context, MAB, OS, CE);
426 S->getAssembler().setRelaxAll(true);