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/ADT/DenseMap.h"
12 #include "llvm/ADT/SmallVector.h"
13 #include "llvm/MC/MCAsmBackend.h"
14 #include "llvm/MC/MCAssembler.h"
15 #include "llvm/MC/MCCodeEmitter.h"
16 #include "llvm/MC/MCContext.h"
17 #include "llvm/MC/MCDwarf.h"
18 #include "llvm/MC/MCExpr.h"
19 #include "llvm/MC/MCInst.h"
20 #include "llvm/MC/MCMachOSymbolFlags.h"
21 #include "llvm/MC/MCObjectFileInfo.h"
22 #include "llvm/MC/MCObjectStreamer.h"
23 #include "llvm/MC/MCSection.h"
24 #include "llvm/MC/MCSectionMachO.h"
25 #include "llvm/MC/MCSymbol.h"
26 #include "llvm/Support/Dwarf.h"
27 #include "llvm/Support/ErrorHandling.h"
28 #include "llvm/Support/raw_ostream.h"
34 class MCMachOStreamer : public MCObjectStreamer {
36 /// LabelSections - true if each section change should emit a linker local
37 /// label for use in relocations for assembler local references. Obviates the
38 /// need for local relocations. False by default.
41 /// HasSectionLabel - map of which sections have already had a non-local
42 /// label emitted to them. Used so we don't emit extraneous linker local
43 /// labels in the middle of the section.
44 DenseMap<const MCSection*, bool> HasSectionLabel;
46 void EmitInstToData(const MCInst &Inst, const MCSubtargetInfo &STI) override;
48 void EmitDataRegion(DataRegionData::KindTy Kind);
49 void EmitDataRegionEnd();
52 MCMachOStreamer(MCContext &Context, MCAsmBackend &MAB, raw_ostream &OS,
53 MCCodeEmitter *Emitter, bool label)
54 : MCObjectStreamer(Context, MAB, OS, Emitter),
55 LabelSections(label) {}
57 /// @name MCStreamer Interface
60 void ChangeSection(const MCSection *Sect, const MCExpr *Subsect) override;
61 void EmitLabel(MCSymbol *Symbol) override;
62 void EmitDebugLabel(MCSymbol *Symbol) override;
63 void EmitEHSymAttributes(const MCSymbol *Symbol, MCSymbol *EHSymbol) override;
64 void EmitAssemblerFlag(MCAssemblerFlag Flag) override;
65 void EmitLinkerOptions(ArrayRef<std::string> Options) override;
66 void EmitDataRegion(MCDataRegionType Kind) override;
67 void EmitVersionMin(MCVersionMinType Kind, unsigned Major,
68 unsigned Minor, unsigned Update) override;
69 void EmitThumbFunc(MCSymbol *Func) override;
70 bool EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) override;
71 void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) override;
72 void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
73 unsigned ByteAlignment) override;
74 void BeginCOFFSymbolDef(const MCSymbol *Symbol) override {
75 llvm_unreachable("macho doesn't support this directive");
77 void EmitCOFFSymbolStorageClass(int StorageClass) override {
78 llvm_unreachable("macho doesn't support this directive");
80 void EmitCOFFSymbolType(int Type) override {
81 llvm_unreachable("macho doesn't support this directive");
83 void EndCOFFSymbolDef() override {
84 llvm_unreachable("macho doesn't support this directive");
86 void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) override {
87 llvm_unreachable("macho doesn't support this directive");
89 void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
90 unsigned ByteAlignment) override;
91 void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
92 uint64_t Size = 0, unsigned ByteAlignment = 0) override;
93 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
94 uint64_t Size, unsigned ByteAlignment = 0) override;
96 void EmitFileDirective(StringRef Filename) override {
97 // FIXME: Just ignore the .file; it isn't important enough to fail the
100 // report_fatal_error("unsupported directive: '.file'");
103 void EmitIdent(StringRef IdentString) override {
104 llvm_unreachable("macho doesn't support this directive");
107 void FinishImpl() override;
110 } // end anonymous namespace.
112 void MCMachOStreamer::ChangeSection(const MCSection *Section,
113 const MCExpr *Subsection) {
114 // Change the section normally.
115 MCObjectStreamer::ChangeSection(Section, Subsection);
116 // Output a linker-local symbol so we don't need section-relative local
117 // relocations. The linker hates us when we do that.
118 if (LabelSections && !HasSectionLabel[Section]) {
119 MCSymbol *Label = getContext().CreateLinkerPrivateTempSymbol();
121 HasSectionLabel[Section] = true;
125 void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
126 MCSymbol *EHSymbol) {
128 getAssembler().getOrCreateSymbolData(*Symbol);
130 EmitSymbolAttribute(EHSymbol, MCSA_Global);
131 if (SD.getFlags() & SF_WeakDefinition)
132 EmitSymbolAttribute(EHSymbol, MCSA_WeakDefinition);
133 if (SD.isPrivateExtern())
134 EmitSymbolAttribute(EHSymbol, MCSA_PrivateExtern);
137 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
138 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
140 // isSymbolLinkerVisible uses the section.
141 AssignSection(Symbol, getCurrentSection().first);
142 // We have to create a new fragment if this is an atom defining symbol,
143 // fragments cannot span atoms.
144 if (getAssembler().isSymbolLinkerVisible(*Symbol))
145 insert(new MCDataFragment());
147 MCObjectStreamer::EmitLabel(Symbol);
149 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
150 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
151 // to clear the weak reference and weak definition bits too, but the
152 // implementation was buggy. For now we just try to match 'as', for
155 // FIXME: Cleanup this code, these bits should be emitted based on semantic
156 // properties, not on the order of definition, etc.
157 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
160 void MCMachOStreamer::EmitDebugLabel(MCSymbol *Symbol) {
163 void MCMachOStreamer::EmitDataRegion(DataRegionData::KindTy Kind) {
164 if (!getAssembler().getBackend().hasDataInCodeSupport())
166 // Create a temporary label to mark the start of the data region.
167 MCSymbol *Start = getContext().CreateTempSymbol();
169 // Record the region for the object writer to use.
170 DataRegionData Data = { Kind, Start, NULL };
171 std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
172 Regions.push_back(Data);
175 void MCMachOStreamer::EmitDataRegionEnd() {
176 if (!getAssembler().getBackend().hasDataInCodeSupport())
178 std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
179 assert(Regions.size() && "Mismatched .end_data_region!");
180 DataRegionData &Data = Regions.back();
181 assert(Data.End == NULL && "Mismatched .end_data_region!");
182 // Create a temporary label to mark the end of the data region.
183 Data.End = getContext().CreateTempSymbol();
187 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
188 // Let the target do whatever target specific stuff it needs to do.
189 getAssembler().getBackend().handleAssemblerFlag(Flag);
190 // Do any generic stuff we need to do.
192 case MCAF_SyntaxUnified: return; // no-op here.
193 case MCAF_Code16: return; // Change parsing mode; no-op here.
194 case MCAF_Code32: return; // Change parsing mode; no-op here.
195 case MCAF_Code64: return; // Change parsing mode; no-op here.
196 case MCAF_SubsectionsViaSymbols:
197 getAssembler().setSubsectionsViaSymbols(true);
202 void MCMachOStreamer::EmitLinkerOptions(ArrayRef<std::string> Options) {
203 getAssembler().getLinkerOptions().push_back(Options);
206 void MCMachOStreamer::EmitDataRegion(MCDataRegionType Kind) {
208 case MCDR_DataRegion:
209 EmitDataRegion(DataRegionData::Data);
211 case MCDR_DataRegionJT8:
212 EmitDataRegion(DataRegionData::JumpTable8);
214 case MCDR_DataRegionJT16:
215 EmitDataRegion(DataRegionData::JumpTable16);
217 case MCDR_DataRegionJT32:
218 EmitDataRegion(DataRegionData::JumpTable32);
220 case MCDR_DataRegionEnd:
226 void MCMachOStreamer::EmitVersionMin(MCVersionMinType Kind, unsigned Major,
227 unsigned Minor, unsigned Update) {
228 getAssembler().setVersionMinInfo(Kind, Major, Minor, Update);
231 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
232 // Remember that the function is a thumb function. Fixup and relocation
233 // values will need adjusted.
234 getAssembler().setIsThumbFunc(Symbol);
236 // Mark the thumb bit on the symbol.
237 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
238 SD.setFlags(SD.getFlags() | SF_ThumbFunc);
241 bool MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
242 MCSymbolAttr Attribute) {
243 // Indirect symbols are handled differently, to match how 'as' handles
244 // them. This makes writing matching .o files easier.
245 if (Attribute == MCSA_IndirectSymbol) {
246 // Note that we intentionally cannot use the symbol data here; this is
247 // important for matching the string table that 'as' generates.
248 IndirectSymbolData ISD;
250 ISD.SectionData = getCurrentSectionData();
251 getAssembler().getIndirectSymbols().push_back(ISD);
255 // Adding a symbol attribute always introduces the symbol, note that an
256 // important side effect of calling getOrCreateSymbolData here is to register
257 // the symbol with the assembler.
258 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
260 // The implementation of symbol attributes is designed to match 'as', but it
261 // leaves much to desired. It doesn't really make sense to arbitrarily add and
262 // remove flags, but 'as' allows this (in particular, see .desc).
264 // In the future it might be worth trying to make these operations more well
268 case MCSA_ELF_TypeFunction:
269 case MCSA_ELF_TypeIndFunction:
270 case MCSA_ELF_TypeObject:
271 case MCSA_ELF_TypeTLS:
272 case MCSA_ELF_TypeCommon:
273 case MCSA_ELF_TypeNoType:
274 case MCSA_ELF_TypeGnuUniqueObject:
276 case MCSA_IndirectSymbol:
284 SD.setExternal(true);
285 // This effectively clears the undefined lazy bit, in Darwin 'as', although
286 // it isn't very consistent because it implements this as part of symbol
289 // FIXME: Cleanup this code, these bits should be emitted based on semantic
290 // properties, not on the order of definition, etc.
291 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
294 case MCSA_LazyReference:
295 // FIXME: This requires -dynamic.
296 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
297 if (Symbol->isUndefined())
298 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
301 // Since .reference sets the no dead strip bit, it is equivalent to
302 // .no_dead_strip in practice.
304 case MCSA_NoDeadStrip:
305 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
308 case MCSA_SymbolResolver:
309 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
312 case MCSA_PrivateExtern:
313 SD.setExternal(true);
314 SD.setPrivateExtern(true);
317 case MCSA_WeakReference:
318 // FIXME: This requires -dynamic.
319 if (Symbol->isUndefined())
320 SD.setFlags(SD.getFlags() | SF_WeakReference);
323 case MCSA_WeakDefinition:
324 // FIXME: 'as' enforces that this is defined and global. The manual claims
325 // it has to be in a coalesced section, but this isn't enforced.
326 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
329 case MCSA_WeakDefAutoPrivate:
330 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
337 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
338 // Encode the 'desc' value into the lowest implementation defined bits.
339 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
340 "Invalid .desc value!");
341 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
342 DescValue & SF_DescFlagsMask);
345 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
346 unsigned ByteAlignment) {
347 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
348 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
350 AssignSection(Symbol, NULL);
352 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
353 SD.setExternal(true);
354 SD.setCommon(Size, ByteAlignment);
357 void MCMachOStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
358 unsigned ByteAlignment) {
359 // '.lcomm' is equivalent to '.zerofill'.
360 return EmitZerofill(getContext().getObjectFileInfo()->getDataBSSSection(),
361 Symbol, Size, ByteAlignment);
364 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
365 uint64_t Size, unsigned ByteAlignment) {
366 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
368 // The symbol may not be present, which only creates the section.
372 // On darwin all virtual sections have zerofill type.
373 assert(Section->isVirtualSection() && "Section does not have zerofill type!");
375 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
377 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
379 // Emit an align fragment if necessary.
380 if (ByteAlignment != 1)
381 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
383 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
386 AssignSection(Symbol, Section);
388 // Update the maximum alignment on the zero fill section if necessary.
389 if (ByteAlignment > SectData.getAlignment())
390 SectData.setAlignment(ByteAlignment);
393 // This should always be called with the thread local bss section. Like the
394 // .zerofill directive this doesn't actually switch sections on us.
395 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
396 uint64_t Size, unsigned ByteAlignment) {
397 EmitZerofill(Section, Symbol, Size, ByteAlignment);
401 void MCMachOStreamer::EmitInstToData(const MCInst &Inst,
402 const MCSubtargetInfo &STI) {
403 MCDataFragment *DF = getOrCreateDataFragment();
405 SmallVector<MCFixup, 4> Fixups;
406 SmallString<256> Code;
407 raw_svector_ostream VecOS(Code);
408 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups, STI);
411 // Add the fixups and data.
412 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
413 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
414 DF->getFixups().push_back(Fixups[i]);
416 DF->getContents().append(Code.begin(), Code.end());
419 void MCMachOStreamer::FinishImpl() {
420 EmitFrames(&getAssembler().getBackend(), true);
422 // We have to set the fragment atom associations so we can relax properly for
425 // First, scan the symbol table to build a lookup table from fragments to
427 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
428 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
429 ie = getAssembler().symbol_end(); it != ie; ++it) {
430 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
432 // An atom defining symbol should never be internal to a fragment.
433 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
434 DefiningSymbolMap[it->getFragment()] = it;
438 // Set the fragment atom associations by tracking the last seen atom defining
440 for (MCAssembler::iterator it = getAssembler().begin(),
441 ie = getAssembler().end(); it != ie; ++it) {
442 MCSymbolData *CurrentAtom = 0;
443 for (MCSectionData::iterator it2 = it->begin(),
444 ie2 = it->end(); it2 != ie2; ++it2) {
445 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
447 it2->setAtom(CurrentAtom);
451 this->MCObjectStreamer::FinishImpl();
454 MCStreamer *llvm::createMachOStreamer(MCContext &Context, MCAsmBackend &MAB,
455 raw_ostream &OS, MCCodeEmitter *CE,
457 bool LabelSections) {
458 MCMachOStreamer *S = new MCMachOStreamer(Context, MAB, OS, CE, LabelSections);
460 S->getAssembler().setRelaxAll(true);