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 EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
52 virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
53 virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
54 unsigned ByteAlignment);
55 virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {
56 llvm_unreachable("macho doesn't support this directive");
58 virtual void EmitCOFFSymbolStorageClass(int StorageClass) {
59 llvm_unreachable("macho doesn't support this directive");
61 virtual void EmitCOFFSymbolType(int Type) {
62 llvm_unreachable("macho doesn't support this directive");
64 virtual void EndCOFFSymbolDef() {
65 llvm_unreachable("macho doesn't support this directive");
67 virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
68 llvm_unreachable("macho doesn't support this directive");
70 virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
71 unsigned ByteAlignment);
72 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
73 uint64_t Size = 0, unsigned ByteAlignment = 0);
74 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
75 uint64_t Size, unsigned ByteAlignment = 0);
77 virtual void EmitFileDirective(StringRef Filename) {
78 // FIXME: Just ignore the .file; it isn't important enough to fail the
81 //report_fatal_error("unsupported directive: '.file'");
84 virtual void FinishImpl();
89 } // end anonymous namespace.
91 void MCMachOStreamer::InitSections() {
92 SwitchSection(getContext().getMachOSection("__TEXT", "__text",
93 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
94 0, SectionKind::getText()));
98 void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
101 getAssembler().getOrCreateSymbolData(*Symbol);
103 EmitSymbolAttribute(EHSymbol, MCSA_Global);
104 if (SD.getFlags() & SF_WeakDefinition)
105 EmitSymbolAttribute(EHSymbol, MCSA_WeakDefinition);
106 if (SD.isPrivateExtern())
107 EmitSymbolAttribute(EHSymbol, MCSA_PrivateExtern);
110 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
111 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
113 // isSymbolLinkerVisible uses the section.
114 Symbol->setSection(*getCurrentSection());
115 // We have to create a new fragment if this is an atom defining symbol,
116 // fragments cannot span atoms.
117 if (getAssembler().isSymbolLinkerVisible(*Symbol))
118 new MCDataFragment(getCurrentSectionData());
120 MCObjectStreamer::EmitLabel(Symbol);
122 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
123 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
124 // to clear the weak reference and weak definition bits too, but the
125 // implementation was buggy. For now we just try to match 'as', for
128 // FIXME: Cleanup this code, these bits should be emitted based on semantic
129 // properties, not on the order of definition, etc.
130 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
133 void MCMachOStreamer::EmitDataRegion(DataRegionData::KindTy Kind) {
134 if (!getAssembler().getBackend().hasDataInCodeSupport())
136 // Create a temporary label to mark the start of the data region.
137 MCSymbol *Start = getContext().CreateTempSymbol();
139 // Record the region for the object writer to use.
140 DataRegionData Data = { Kind, Start, NULL };
141 std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
142 Regions.push_back(Data);
145 void MCMachOStreamer::EmitDataRegionEnd() {
146 if (!getAssembler().getBackend().hasDataInCodeSupport())
148 std::vector<DataRegionData> &Regions = getAssembler().getDataRegions();
149 assert(Regions.size() && "Mismatched .end_data_region!");
150 DataRegionData &Data = Regions.back();
151 assert(Data.End == NULL && "Mismatched .end_data_region!");
152 // Create a temporary label to mark the end of the data region.
153 Data.End = getContext().CreateTempSymbol();
157 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
158 // Let the target do whatever target specific stuff it needs to do.
159 getAssembler().getBackend().handleAssemblerFlag(Flag);
160 // Do any generic stuff we need to do.
162 case MCAF_SyntaxUnified: return; // no-op here.
163 case MCAF_Code16: return; // Change parsing mode; no-op here.
164 case MCAF_Code32: return; // Change parsing mode; no-op here.
165 case MCAF_Code64: return; // Change parsing mode; no-op here.
166 case MCAF_SubsectionsViaSymbols:
167 getAssembler().setSubsectionsViaSymbols(true);
172 void MCMachOStreamer::EmitDataRegion(MCDataRegionType Kind) {
174 case MCDR_DataRegion:
175 EmitDataRegion(DataRegionData::Data);
177 case MCDR_DataRegionJT8:
178 EmitDataRegion(DataRegionData::JumpTable8);
180 case MCDR_DataRegionJT16:
181 EmitDataRegion(DataRegionData::JumpTable16);
183 case MCDR_DataRegionJT32:
184 EmitDataRegion(DataRegionData::JumpTable32);
186 case MCDR_DataRegionEnd:
192 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
193 // Remember that the function is a thumb function. Fixup and relocation
194 // values will need adjusted.
195 getAssembler().setIsThumbFunc(Symbol);
197 // Mark the thumb bit on the symbol.
198 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
199 SD.setFlags(SD.getFlags() | SF_ThumbFunc);
202 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
203 MCSymbolAttr Attribute) {
204 // Indirect symbols are handled differently, to match how 'as' handles
205 // them. This makes writing matching .o files easier.
206 if (Attribute == MCSA_IndirectSymbol) {
207 // Note that we intentionally cannot use the symbol data here; this is
208 // important for matching the string table that 'as' generates.
209 IndirectSymbolData ISD;
211 ISD.SectionData = getCurrentSectionData();
212 getAssembler().getIndirectSymbols().push_back(ISD);
216 // Adding a symbol attribute always introduces the symbol, note that an
217 // important side effect of calling getOrCreateSymbolData here is to register
218 // the symbol with the assembler.
219 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
221 // The implementation of symbol attributes is designed to match 'as', but it
222 // leaves much to desired. It doesn't really make sense to arbitrarily add and
223 // remove flags, but 'as' allows this (in particular, see .desc).
225 // In the future it might be worth trying to make these operations more well
229 case MCSA_ELF_TypeFunction:
230 case MCSA_ELF_TypeIndFunction:
231 case MCSA_ELF_TypeObject:
232 case MCSA_ELF_TypeTLS:
233 case MCSA_ELF_TypeCommon:
234 case MCSA_ELF_TypeNoType:
235 case MCSA_ELF_TypeGnuUniqueObject:
237 case MCSA_IndirectSymbol:
242 llvm_unreachable("Invalid symbol attribute for Mach-O!");
245 SD.setExternal(true);
246 // This effectively clears the undefined lazy bit, in Darwin 'as', although
247 // it isn't very consistent because it implements this as part of symbol
250 // FIXME: Cleanup this code, these bits should be emitted based on semantic
251 // properties, not on the order of definition, etc.
252 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
255 case MCSA_LazyReference:
256 // FIXME: This requires -dynamic.
257 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
258 if (Symbol->isUndefined())
259 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
262 // Since .reference sets the no dead strip bit, it is equivalent to
263 // .no_dead_strip in practice.
265 case MCSA_NoDeadStrip:
266 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
269 case MCSA_SymbolResolver:
270 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
273 case MCSA_PrivateExtern:
274 SD.setExternal(true);
275 SD.setPrivateExtern(true);
278 case MCSA_WeakReference:
279 // FIXME: This requires -dynamic.
280 if (Symbol->isUndefined())
281 SD.setFlags(SD.getFlags() | SF_WeakReference);
284 case MCSA_WeakDefinition:
285 // FIXME: 'as' enforces that this is defined and global. The manual claims
286 // it has to be in a coalesced section, but this isn't enforced.
287 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
290 case MCSA_WeakDefAutoPrivate:
291 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
296 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
297 // Encode the 'desc' value into the lowest implementation defined bits.
298 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
299 "Invalid .desc value!");
300 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
301 DescValue & SF_DescFlagsMask);
304 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
305 unsigned ByteAlignment) {
306 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
307 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
309 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
310 SD.setExternal(true);
311 SD.setCommon(Size, ByteAlignment);
314 void MCMachOStreamer::EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
315 unsigned ByteAlignment) {
316 // '.lcomm' is equivalent to '.zerofill'.
317 return EmitZerofill(getContext().getMachOSection("__DATA", "__bss",
318 MCSectionMachO::S_ZEROFILL,
319 0, SectionKind::getBSS()),
320 Symbol, Size, ByteAlignment);
323 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
324 uint64_t Size, unsigned ByteAlignment) {
325 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
327 // The symbol may not be present, which only creates the section.
331 // FIXME: Assert that this section has the zerofill type.
333 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
335 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
337 // Emit an align fragment if necessary.
338 if (ByteAlignment != 1)
339 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
341 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
344 Symbol->setSection(*Section);
346 // Update the maximum alignment on the zero fill section if necessary.
347 if (ByteAlignment > SectData.getAlignment())
348 SectData.setAlignment(ByteAlignment);
351 // This should always be called with the thread local bss section. Like the
352 // .zerofill directive this doesn't actually switch sections on us.
353 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
354 uint64_t Size, unsigned ByteAlignment) {
355 EmitZerofill(Section, Symbol, Size, ByteAlignment);
359 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
360 MCDataFragment *DF = getOrCreateDataFragment();
362 SmallVector<MCFixup, 4> Fixups;
363 SmallString<256> Code;
364 raw_svector_ostream VecOS(Code);
365 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
368 // Add the fixups and data.
369 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
370 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
371 DF->addFixup(Fixups[i]);
373 DF->getContents().append(Code.begin(), Code.end());
376 void MCMachOStreamer::FinishImpl() {
379 // We have to set the fragment atom associations so we can relax properly for
382 // First, scan the symbol table to build a lookup table from fragments to
384 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
385 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
386 ie = getAssembler().symbol_end(); it != ie; ++it) {
387 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
389 // An atom defining symbol should never be internal to a fragment.
390 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
391 DefiningSymbolMap[it->getFragment()] = it;
395 // Set the fragment atom associations by tracking the last seen atom defining
397 for (MCAssembler::iterator it = getAssembler().begin(),
398 ie = getAssembler().end(); it != ie; ++it) {
399 MCSymbolData *CurrentAtom = 0;
400 for (MCSectionData::iterator it2 = it->begin(),
401 ie2 = it->end(); it2 != ie2; ++it2) {
402 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
404 it2->setAtom(CurrentAtom);
408 this->MCObjectStreamer::FinishImpl();
411 MCStreamer *llvm::createMachOStreamer(MCContext &Context, MCAsmBackend &MAB,
412 raw_ostream &OS, MCCodeEmitter *CE,
414 MCMachOStreamer *S = new MCMachOStreamer(Context, MAB, OS, CE);
416 S->getAssembler().setRelaxAll(true);