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 llvm_unreachable("macho doesn't support this directive");
76 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
77 unsigned Size = 0, unsigned ByteAlignment = 0);
78 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
79 uint64_t Size, unsigned ByteAlignment = 0);
80 virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
81 virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
82 unsigned ValueSize = 1,
83 unsigned MaxBytesToEmit = 0);
84 virtual void EmitCodeAlignment(unsigned ByteAlignment,
85 unsigned MaxBytesToEmit = 0);
87 virtual void EmitFileDirective(StringRef Filename) {
88 // FIXME: Just ignore the .file; it isn't important enough to fail the
91 //report_fatal_error("unsupported directive: '.file'");
94 virtual void FinishImpl();
99 } // end anonymous namespace.
101 void MCMachOStreamer::InitSections() {
102 SwitchSection(getContext().getMachOSection("__TEXT", "__text",
103 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
104 0, SectionKind::getText()));
108 void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
109 MCSymbol *EHSymbol) {
111 getAssembler().getOrCreateSymbolData(*Symbol);
113 EmitSymbolAttribute(EHSymbol, MCSA_Global);
114 if (SD.getFlags() & SF_WeakDefinition)
115 EmitSymbolAttribute(EHSymbol, MCSA_WeakDefinition);
116 if (SD.isPrivateExtern())
117 EmitSymbolAttribute(EHSymbol, MCSA_PrivateExtern);
120 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
121 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
123 // isSymbolLinkerVisible uses the section.
124 Symbol->setSection(*getCurrentSection());
125 // We have to create a new fragment if this is an atom defining symbol,
126 // fragments cannot span atoms.
127 if (getAssembler().isSymbolLinkerVisible(*Symbol))
128 new MCDataFragment(getCurrentSectionData());
130 MCObjectStreamer::EmitLabel(Symbol);
132 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
133 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
134 // to clear the weak reference and weak definition bits too, but the
135 // implementation was buggy. For now we just try to match 'as', for
138 // FIXME: Cleanup this code, these bits should be emitted based on semantic
139 // properties, not on the order of definition, etc.
140 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
143 void MCMachOStreamer::EmitDataRegion(DataRegionData::KindTy Kind) {
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 std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
155 assert(Regions.size() && "Mismatched .end_data_region!");
156 DataRegionData &Data = Regions.back();
157 assert(Data.End == NULL && "Mismatched .end_data_region!");
158 // Create a temporary label to mark the end of the data region.
159 Data.End = getContext().CreateTempSymbol();
163 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
164 // Let the target do whatever target specific stuff it needs to do.
165 getAssembler().getBackend().handleAssemblerFlag(Flag);
166 // Do any generic stuff we need to do.
168 case MCAF_SyntaxUnified: return; // no-op here.
169 case MCAF_Code16: return; // Change parsing mode; no-op here.
170 case MCAF_Code32: return; // Change parsing mode; no-op here.
171 case MCAF_Code64: return; // Change parsing mode; no-op here.
172 case MCAF_SubsectionsViaSymbols:
173 getAssembler().setSubsectionsViaSymbols(true);
178 void MCMachOStreamer::EmitDataRegion(MCDataRegionType Kind) {
180 case MCDR_DataRegion:
181 EmitDataRegion(DataRegionData::Data);
183 case MCDR_DataRegionJT8:
184 EmitDataRegion(DataRegionData::JumpTable8);
186 case MCDR_DataRegionJT16:
187 EmitDataRegion(DataRegionData::JumpTable16);
189 case MCDR_DataRegionJT32:
190 EmitDataRegion(DataRegionData::JumpTable32);
192 case MCDR_DataRegionEnd:
198 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
199 // Remember that the function is a thumb function. Fixup and relocation
200 // values will need adjusted.
201 getAssembler().setIsThumbFunc(Symbol);
203 // Mark the thumb bit on the symbol.
204 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
205 SD.setFlags(SD.getFlags() | SF_ThumbFunc);
208 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
209 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
211 // FIXME: Lift context changes into super class.
212 getAssembler().getOrCreateSymbolData(*Symbol);
213 Symbol->setVariableValue(AddValueSymbols(Value));
216 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
217 MCSymbolAttr Attribute) {
218 // Indirect symbols are handled differently, to match how 'as' handles
219 // them. This makes writing matching .o files easier.
220 if (Attribute == MCSA_IndirectSymbol) {
221 // Note that we intentionally cannot use the symbol data here; this is
222 // important for matching the string table that 'as' generates.
223 IndirectSymbolData ISD;
225 ISD.SectionData = getCurrentSectionData();
226 getAssembler().getIndirectSymbols().push_back(ISD);
230 // Adding a symbol attribute always introduces the symbol, note that an
231 // important side effect of calling getOrCreateSymbolData here is to register
232 // the symbol with the assembler.
233 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
235 // The implementation of symbol attributes is designed to match 'as', but it
236 // leaves much to desired. It doesn't really make sense to arbitrarily add and
237 // remove flags, but 'as' allows this (in particular, see .desc).
239 // In the future it might be worth trying to make these operations more well
243 case MCSA_ELF_TypeFunction:
244 case MCSA_ELF_TypeIndFunction:
245 case MCSA_ELF_TypeObject:
246 case MCSA_ELF_TypeTLS:
247 case MCSA_ELF_TypeCommon:
248 case MCSA_ELF_TypeNoType:
249 case MCSA_ELF_TypeGnuUniqueObject:
251 case MCSA_IndirectSymbol:
256 llvm_unreachable("Invalid symbol attribute for Mach-O!");
259 SD.setExternal(true);
260 // This effectively clears the undefined lazy bit, in Darwin 'as', although
261 // it isn't very consistent because it implements this as part of symbol
264 // FIXME: Cleanup this code, these bits should be emitted based on semantic
265 // properties, not on the order of definition, etc.
266 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
269 case MCSA_LazyReference:
270 // FIXME: This requires -dynamic.
271 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
272 if (Symbol->isUndefined())
273 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
276 // Since .reference sets the no dead strip bit, it is equivalent to
277 // .no_dead_strip in practice.
279 case MCSA_NoDeadStrip:
280 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
283 case MCSA_SymbolResolver:
284 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
287 case MCSA_PrivateExtern:
288 SD.setExternal(true);
289 SD.setPrivateExtern(true);
292 case MCSA_WeakReference:
293 // FIXME: This requires -dynamic.
294 if (Symbol->isUndefined())
295 SD.setFlags(SD.getFlags() | SF_WeakReference);
298 case MCSA_WeakDefinition:
299 // FIXME: 'as' enforces that this is defined and global. The manual claims
300 // it has to be in a coalesced section, but this isn't enforced.
301 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
304 case MCSA_WeakDefAutoPrivate:
305 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
310 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
311 // Encode the 'desc' value into the lowest implementation defined bits.
312 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
313 "Invalid .desc value!");
314 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
315 DescValue & SF_DescFlagsMask);
318 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
319 unsigned ByteAlignment) {
320 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
321 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
323 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
324 SD.setExternal(true);
325 SD.setCommon(Size, ByteAlignment);
328 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
329 unsigned Size, unsigned ByteAlignment) {
330 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
332 // The symbol may not be present, which only creates the section.
336 // FIXME: Assert that this section has the zerofill type.
338 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
340 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
342 // Emit an align fragment if necessary.
343 if (ByteAlignment != 1)
344 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
346 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
349 Symbol->setSection(*Section);
351 // Update the maximum alignment on the zero fill section if necessary.
352 if (ByteAlignment > SectData.getAlignment())
353 SectData.setAlignment(ByteAlignment);
356 // This should always be called with the thread local bss section. Like the
357 // .zerofill directive this doesn't actually switch sections on us.
358 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
359 uint64_t Size, unsigned ByteAlignment) {
360 EmitZerofill(Section, Symbol, Size, ByteAlignment);
364 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
365 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
367 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
370 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
371 int64_t Value, unsigned ValueSize,
372 unsigned MaxBytesToEmit) {
373 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
375 if (MaxBytesToEmit == 0)
376 MaxBytesToEmit = ByteAlignment;
377 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
378 getCurrentSectionData());
380 // Update the maximum alignment on the current section if necessary.
381 if (ByteAlignment > getCurrentSectionData()->getAlignment())
382 getCurrentSectionData()->setAlignment(ByteAlignment);
385 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
386 unsigned MaxBytesToEmit) {
387 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
389 if (MaxBytesToEmit == 0)
390 MaxBytesToEmit = ByteAlignment;
391 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
392 getCurrentSectionData());
393 F->setEmitNops(true);
395 // Update the maximum alignment on the current section if necessary.
396 if (ByteAlignment > getCurrentSectionData()->getAlignment())
397 getCurrentSectionData()->setAlignment(ByteAlignment);
400 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
401 MCDataFragment *DF = getOrCreateDataFragment();
403 SmallVector<MCFixup, 4> Fixups;
404 SmallString<256> Code;
405 raw_svector_ostream VecOS(Code);
406 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
409 // Add the fixups and data.
410 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
411 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
412 DF->addFixup(Fixups[i]);
414 DF->getContents().append(Code.begin(), Code.end());
417 void MCMachOStreamer::FinishImpl() {
420 // We have to set the fragment atom associations so we can relax properly for
423 // First, scan the symbol table to build a lookup table from fragments to
425 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
426 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
427 ie = getAssembler().symbol_end(); it != ie; ++it) {
428 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
430 // An atom defining symbol should never be internal to a fragment.
431 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
432 DefiningSymbolMap[it->getFragment()] = it;
436 // Set the fragment atom associations by tracking the last seen atom defining
438 for (MCAssembler::iterator it = getAssembler().begin(),
439 ie = getAssembler().end(); it != ie; ++it) {
440 MCSymbolData *CurrentAtom = 0;
441 for (MCSectionData::iterator it2 = it->begin(),
442 ie2 = it->end(); it2 != ie2; ++it2) {
443 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
445 it2->setAtom(CurrentAtom);
449 this->MCObjectStreamer::FinishImpl();
452 MCStreamer *llvm::createMachOStreamer(MCContext &Context, MCAsmBackend &MAB,
453 raw_ostream &OS, MCCodeEmitter *CE,
455 MCMachOStreamer *S = new MCMachOStreamer(Context, MAB, OS, CE);
457 S->getAssembler().setRelaxAll(true);