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"
10 #include "llvm/MC/MCAsmBackend.h"
11 #include "llvm/MC/MCAssembler.h"
12 #include "llvm/MC/MCCodeEmitter.h"
13 #include "llvm/MC/MCContext.h"
14 #include "llvm/MC/MCDwarf.h"
15 #include "llvm/MC/MCExpr.h"
16 #include "llvm/MC/MCInst.h"
17 #include "llvm/MC/MCMachOSymbolFlags.h"
18 #include "llvm/MC/MCObjectStreamer.h"
19 #include "llvm/MC/MCSection.h"
20 #include "llvm/MC/MCSectionMachO.h"
21 #include "llvm/MC/MCSymbol.h"
22 #include "llvm/Support/Dwarf.h"
23 #include "llvm/Support/ErrorHandling.h"
24 #include "llvm/Support/raw_ostream.h"
30 class MCMachOStreamer : public MCObjectStreamer {
32 virtual void EmitInstToData(const MCInst &Inst);
34 void EmitDataRegion(DataRegionData::KindTy Kind);
35 void EmitDataRegionEnd();
37 MCMachOStreamer(MCContext &Context, MCAsmBackend &MAB, raw_ostream &OS,
38 MCCodeEmitter *Emitter)
39 : MCObjectStreamer(SK_MachOStreamer, Context, MAB, OS, Emitter) {}
41 /// @name MCStreamer Interface
44 virtual void InitSections();
45 virtual void InitToTextSection();
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 void 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 FinishImpl();
91 static bool classof(const MCStreamer *S) {
92 return S->getKind() == SK_MachOStreamer;
96 } // end anonymous namespace.
98 void MCMachOStreamer::InitSections() {
102 void MCMachOStreamer::InitToTextSection() {
103 SwitchSection(getContext().getMachOSection(
105 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS, 0,
106 SectionKind::getText()));
109 void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
110 MCSymbol *EHSymbol) {
112 getAssembler().getOrCreateSymbolData(*Symbol);
114 EmitSymbolAttribute(EHSymbol, MCSA_Global);
115 if (SD.getFlags() & SF_WeakDefinition)
116 EmitSymbolAttribute(EHSymbol, MCSA_WeakDefinition);
117 if (SD.isPrivateExtern())
118 EmitSymbolAttribute(EHSymbol, MCSA_PrivateExtern);
121 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
122 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
124 // isSymbolLinkerVisible uses the section.
125 Symbol->setSection(*getCurrentSection().first);
126 // We have to create a new fragment if this is an atom defining symbol,
127 // fragments cannot span atoms.
128 if (getAssembler().isSymbolLinkerVisible(*Symbol))
129 insert(new MCDataFragment());
131 MCObjectStreamer::EmitLabel(Symbol);
133 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
134 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
135 // to clear the weak reference and weak definition bits too, but the
136 // implementation was buggy. For now we just try to match 'as', for
139 // FIXME: Cleanup this code, these bits should be emitted based on semantic
140 // properties, not on the order of definition, etc.
141 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
144 void MCMachOStreamer::EmitDebugLabel(MCSymbol *Symbol) {
147 void MCMachOStreamer::EmitDataRegion(DataRegionData::KindTy Kind) {
148 if (!getAssembler().getBackend().hasDataInCodeSupport())
150 // Create a temporary label to mark the start of the data region.
151 MCSymbol *Start = getContext().CreateTempSymbol();
153 // Record the region for the object writer to use.
154 DataRegionData Data = { Kind, Start, NULL };
155 std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
156 Regions.push_back(Data);
159 void MCMachOStreamer::EmitDataRegionEnd() {
160 if (!getAssembler().getBackend().hasDataInCodeSupport())
162 std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
163 assert(Regions.size() && "Mismatched .end_data_region!");
164 DataRegionData &Data = Regions.back();
165 assert(Data.End == NULL && "Mismatched .end_data_region!");
166 // Create a temporary label to mark the end of the data region.
167 Data.End = getContext().CreateTempSymbol();
171 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
172 // Let the target do whatever target specific stuff it needs to do.
173 getAssembler().getBackend().handleAssemblerFlag(Flag);
174 // Do any generic stuff we need to do.
176 case MCAF_SyntaxUnified: return; // no-op here.
177 case MCAF_Code16: return; // Change parsing mode; no-op here.
178 case MCAF_Code32: return; // Change parsing mode; no-op here.
179 case MCAF_Code64: return; // Change parsing mode; no-op here.
180 case MCAF_SubsectionsViaSymbols:
181 getAssembler().setSubsectionsViaSymbols(true);
186 void MCMachOStreamer::EmitLinkerOptions(ArrayRef<std::string> Options) {
187 getAssembler().getLinkerOptions().push_back(Options);
190 void MCMachOStreamer::EmitDataRegion(MCDataRegionType Kind) {
192 case MCDR_DataRegion:
193 EmitDataRegion(DataRegionData::Data);
195 case MCDR_DataRegionJT8:
196 EmitDataRegion(DataRegionData::JumpTable8);
198 case MCDR_DataRegionJT16:
199 EmitDataRegion(DataRegionData::JumpTable16);
201 case MCDR_DataRegionJT32:
202 EmitDataRegion(DataRegionData::JumpTable32);
204 case MCDR_DataRegionEnd:
210 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
211 // Remember that the function is a thumb function. Fixup and relocation
212 // values will need adjusted.
213 getAssembler().setIsThumbFunc(Symbol);
215 // Mark the thumb bit on the symbol.
216 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
217 SD.setFlags(SD.getFlags() | SF_ThumbFunc);
220 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
221 MCSymbolAttr Attribute) {
222 // Indirect symbols are handled differently, to match how 'as' handles
223 // them. This makes writing matching .o files easier.
224 if (Attribute == MCSA_IndirectSymbol) {
225 // Note that we intentionally cannot use the symbol data here; this is
226 // important for matching the string table that 'as' generates.
227 IndirectSymbolData ISD;
229 ISD.SectionData = getCurrentSectionData();
230 getAssembler().getIndirectSymbols().push_back(ISD);
234 // Adding a symbol attribute always introduces the symbol, note that an
235 // important side effect of calling getOrCreateSymbolData here is to register
236 // the symbol with the assembler.
237 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
239 // The implementation of symbol attributes is designed to match 'as', but it
240 // leaves much to desired. It doesn't really make sense to arbitrarily add and
241 // remove flags, but 'as' allows this (in particular, see .desc).
243 // In the future it might be worth trying to make these operations more well
247 case MCSA_ELF_TypeFunction:
248 case MCSA_ELF_TypeIndFunction:
249 case MCSA_ELF_TypeObject:
250 case MCSA_ELF_TypeTLS:
251 case MCSA_ELF_TypeCommon:
252 case MCSA_ELF_TypeNoType:
253 case MCSA_ELF_TypeGnuUniqueObject:
255 case MCSA_IndirectSymbol:
260 llvm_unreachable("Invalid symbol attribute for Mach-O!");
263 SD.setExternal(true);
264 // This effectively clears the undefined lazy bit, in Darwin 'as', although
265 // it isn't very consistent because it implements this as part of symbol
268 // FIXME: Cleanup this code, these bits should be emitted based on semantic
269 // properties, not on the order of definition, etc.
270 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
273 case MCSA_LazyReference:
274 // FIXME: This requires -dynamic.
275 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
276 if (Symbol->isUndefined())
277 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
280 // Since .reference sets the no dead strip bit, it is equivalent to
281 // .no_dead_strip in practice.
283 case MCSA_NoDeadStrip:
284 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
287 case MCSA_SymbolResolver:
288 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
291 case MCSA_PrivateExtern:
292 SD.setExternal(true);
293 SD.setPrivateExtern(true);
296 case MCSA_WeakReference:
297 // FIXME: This requires -dynamic.
298 if (Symbol->isUndefined())
299 SD.setFlags(SD.getFlags() | SF_WeakReference);
302 case MCSA_WeakDefinition:
303 // FIXME: 'as' enforces that this is defined and global. The manual claims
304 // it has to be in a coalesced section, but this isn't enforced.
305 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
308 case MCSA_WeakDefAutoPrivate:
309 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
314 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
315 // Encode the 'desc' value into the lowest implementation defined bits.
316 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
317 "Invalid .desc value!");
318 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
319 DescValue & SF_DescFlagsMask);
322 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
323 unsigned ByteAlignment) {
324 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
325 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
327 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
328 SD.setExternal(true);
329 SD.setCommon(Size, ByteAlignment);
332 void MCMachOStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
333 unsigned ByteAlignment) {
334 // '.lcomm' is equivalent to '.zerofill'.
335 return EmitZerofill(getContext().getMachOSection("__DATA", "__bss",
336 MCSectionMachO::S_ZEROFILL,
337 0, SectionKind::getBSS()),
338 Symbol, Size, ByteAlignment);
341 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
342 uint64_t Size, unsigned ByteAlignment) {
343 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
345 // The symbol may not be present, which only creates the section.
349 // FIXME: Assert that this section has the zerofill type.
351 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
353 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
355 // Emit an align fragment if necessary.
356 if (ByteAlignment != 1)
357 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
359 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
362 Symbol->setSection(*Section);
364 // Update the maximum alignment on the zero fill section if necessary.
365 if (ByteAlignment > SectData.getAlignment())
366 SectData.setAlignment(ByteAlignment);
369 // This should always be called with the thread local bss section. Like the
370 // .zerofill directive this doesn't actually switch sections on us.
371 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
372 uint64_t Size, unsigned ByteAlignment) {
373 EmitZerofill(Section, Symbol, Size, ByteAlignment);
377 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
378 MCDataFragment *DF = getOrCreateDataFragment();
380 SmallVector<MCFixup, 4> Fixups;
381 SmallString<256> Code;
382 raw_svector_ostream VecOS(Code);
383 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
386 // Add the fixups and data.
387 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
388 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
389 DF->getFixups().push_back(Fixups[i]);
391 DF->getContents().append(Code.begin(), Code.end());
394 void MCMachOStreamer::FinishImpl() {
397 // We have to set the fragment atom associations so we can relax properly for
400 // First, scan the symbol table to build a lookup table from fragments to
402 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
403 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
404 ie = getAssembler().symbol_end(); it != ie; ++it) {
405 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
407 // An atom defining symbol should never be internal to a fragment.
408 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
409 DefiningSymbolMap[it->getFragment()] = it;
413 // Set the fragment atom associations by tracking the last seen atom defining
415 for (MCAssembler::iterator it = getAssembler().begin(),
416 ie = getAssembler().end(); it != ie; ++it) {
417 MCSymbolData *CurrentAtom = 0;
418 for (MCSectionData::iterator it2 = it->begin(),
419 ie2 = it->end(); it2 != ie2; ++it2) {
420 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
422 it2->setAtom(CurrentAtom);
426 this->MCObjectStreamer::FinishImpl();
429 MCStreamer *llvm::createMachOStreamer(MCContext &Context, MCAsmBackend &MAB,
430 raw_ostream &OS, MCCodeEmitter *CE,
432 MCMachOStreamer *S = new MCMachOStreamer(Context, MAB, OS, CE);
434 S->getAssembler().setRelaxAll(true);