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,
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 EmitDataRegion(MCDataRegionType Kind);
50 virtual void EmitThumbFunc(MCSymbol *Func);
51 virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
52 virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
53 virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
54 virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
55 unsigned ByteAlignment);
56 virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {
57 llvm_unreachable("macho doesn't support this directive");
59 virtual void EmitCOFFSymbolStorageClass(int StorageClass) {
60 llvm_unreachable("macho doesn't support this directive");
62 virtual void EmitCOFFSymbolType(int Type) {
63 llvm_unreachable("macho doesn't support this directive");
65 virtual void EndCOFFSymbolDef() {
66 llvm_unreachable("macho doesn't support this directive");
68 virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
69 llvm_unreachable("macho doesn't support this directive");
71 virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
72 unsigned ByteAlignment);
73 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
74 uint64_t Size = 0, unsigned ByteAlignment = 0);
75 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
76 uint64_t Size, unsigned ByteAlignment = 0);
78 virtual void EmitFileDirective(StringRef Filename) {
79 // FIXME: Just ignore the .file; it isn't important enough to fail the
82 //report_fatal_error("unsupported directive: '.file'");
85 virtual void FinishImpl();
90 } // end anonymous namespace.
92 void MCMachOStreamer::InitSections() {
93 SwitchSection(getContext().getMachOSection("__TEXT", "__text",
94 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
95 0, SectionKind::getText()));
99 void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
100 MCSymbol *EHSymbol) {
102 getAssembler().getOrCreateSymbolData(*Symbol);
104 EmitSymbolAttribute(EHSymbol, MCSA_Global);
105 if (SD.getFlags() & SF_WeakDefinition)
106 EmitSymbolAttribute(EHSymbol, MCSA_WeakDefinition);
107 if (SD.isPrivateExtern())
108 EmitSymbolAttribute(EHSymbol, MCSA_PrivateExtern);
111 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
112 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
114 // isSymbolLinkerVisible uses the section.
115 Symbol->setSection(*getCurrentSection());
116 // We have to create a new fragment if this is an atom defining symbol,
117 // fragments cannot span atoms.
118 if (getAssembler().isSymbolLinkerVisible(*Symbol))
119 new MCDataFragment(getCurrentSectionData());
121 MCObjectStreamer::EmitLabel(Symbol);
123 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
124 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
125 // to clear the weak reference and weak definition bits too, but the
126 // implementation was buggy. For now we just try to match 'as', for
129 // FIXME: Cleanup this code, these bits should be emitted based on semantic
130 // properties, not on the order of definition, etc.
131 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
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::EmitDataRegion(MCDataRegionType Kind) {
175 case MCDR_DataRegion:
176 EmitDataRegion(DataRegionData::Data);
178 case MCDR_DataRegionJT8:
179 EmitDataRegion(DataRegionData::JumpTable8);
181 case MCDR_DataRegionJT16:
182 EmitDataRegion(DataRegionData::JumpTable16);
184 case MCDR_DataRegionJT32:
185 EmitDataRegion(DataRegionData::JumpTable32);
187 case MCDR_DataRegionEnd:
193 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
194 // Remember that the function is a thumb function. Fixup and relocation
195 // values will need adjusted.
196 getAssembler().setIsThumbFunc(Symbol);
198 // Mark the thumb bit on the symbol.
199 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
200 SD.setFlags(SD.getFlags() | SF_ThumbFunc);
203 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
204 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
206 // FIXME: Lift context changes into super class.
207 getAssembler().getOrCreateSymbolData(*Symbol);
208 Symbol->setVariableValue(AddValueSymbols(Value));
211 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
212 MCSymbolAttr Attribute) {
213 // Indirect symbols are handled differently, to match how 'as' handles
214 // them. This makes writing matching .o files easier.
215 if (Attribute == MCSA_IndirectSymbol) {
216 // Note that we intentionally cannot use the symbol data here; this is
217 // important for matching the string table that 'as' generates.
218 IndirectSymbolData ISD;
220 ISD.SectionData = getCurrentSectionData();
221 getAssembler().getIndirectSymbols().push_back(ISD);
225 // Adding a symbol attribute always introduces the symbol, note that an
226 // important side effect of calling getOrCreateSymbolData here is to register
227 // the symbol with the assembler.
228 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
230 // The implementation of symbol attributes is designed to match 'as', but it
231 // leaves much to desired. It doesn't really make sense to arbitrarily add and
232 // remove flags, but 'as' allows this (in particular, see .desc).
234 // In the future it might be worth trying to make these operations more well
238 case MCSA_ELF_TypeFunction:
239 case MCSA_ELF_TypeIndFunction:
240 case MCSA_ELF_TypeObject:
241 case MCSA_ELF_TypeTLS:
242 case MCSA_ELF_TypeCommon:
243 case MCSA_ELF_TypeNoType:
244 case MCSA_ELF_TypeGnuUniqueObject:
246 case MCSA_IndirectSymbol:
251 llvm_unreachable("Invalid symbol attribute for Mach-O!");
254 SD.setExternal(true);
255 // This effectively clears the undefined lazy bit, in Darwin 'as', although
256 // it isn't very consistent because it implements this as part of symbol
259 // FIXME: Cleanup this code, these bits should be emitted based on semantic
260 // properties, not on the order of definition, etc.
261 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
264 case MCSA_LazyReference:
265 // FIXME: This requires -dynamic.
266 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
267 if (Symbol->isUndefined())
268 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
271 // Since .reference sets the no dead strip bit, it is equivalent to
272 // .no_dead_strip in practice.
274 case MCSA_NoDeadStrip:
275 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
278 case MCSA_SymbolResolver:
279 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
282 case MCSA_PrivateExtern:
283 SD.setExternal(true);
284 SD.setPrivateExtern(true);
287 case MCSA_WeakReference:
288 // FIXME: This requires -dynamic.
289 if (Symbol->isUndefined())
290 SD.setFlags(SD.getFlags() | SF_WeakReference);
293 case MCSA_WeakDefinition:
294 // FIXME: 'as' enforces that this is defined and global. The manual claims
295 // it has to be in a coalesced section, but this isn't enforced.
296 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
299 case MCSA_WeakDefAutoPrivate:
300 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
305 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
306 // Encode the 'desc' value into the lowest implementation defined bits.
307 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
308 "Invalid .desc value!");
309 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
310 DescValue & SF_DescFlagsMask);
313 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
314 unsigned ByteAlignment) {
315 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
316 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
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().getMachOSection("__DATA", "__bss",
327 MCSectionMachO::S_ZEROFILL,
328 0, SectionKind::getBSS()),
329 Symbol, Size, ByteAlignment);
332 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
333 uint64_t Size, unsigned ByteAlignment) {
334 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
336 // The symbol may not be present, which only creates the section.
340 // FIXME: Assert that this section has the zerofill type.
342 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
344 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
346 // Emit an align fragment if necessary.
347 if (ByteAlignment != 1)
348 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
350 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
353 Symbol->setSection(*Section);
355 // Update the maximum alignment on the zero fill section if necessary.
356 if (ByteAlignment > SectData.getAlignment())
357 SectData.setAlignment(ByteAlignment);
360 // This should always be called with the thread local bss section. Like the
361 // .zerofill directive this doesn't actually switch sections on us.
362 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
363 uint64_t Size, unsigned ByteAlignment) {
364 EmitZerofill(Section, Symbol, Size, ByteAlignment);
368 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
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);
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->addFixup(Fixups[i]);
382 DF->getContents().append(Code.begin(), Code.end());
385 void MCMachOStreamer::FinishImpl() {
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);