1 //===- lib/MC/MCMachOStreamer.cpp - Mach-O Object Output ------------===//
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"
12 #include "llvm/MC/MCAssembler.h"
13 #include "llvm/MC/MCContext.h"
14 #include "llvm/MC/MCCodeEmitter.h"
15 #include "llvm/MC/MCExpr.h"
16 #include "llvm/MC/MCInst.h"
17 #include "llvm/MC/MCObjectStreamer.h"
18 #include "llvm/MC/MCSection.h"
19 #include "llvm/MC/MCSymbol.h"
20 #include "llvm/MC/MCMachOSymbolFlags.h"
21 #include "llvm/MC/MCSectionMachO.h"
22 #include "llvm/MC/MCDwarf.h"
23 #include "llvm/MC/MCAsmBackend.h"
24 #include "llvm/Support/Dwarf.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/raw_ostream.h"
32 class MCMachOStreamer : public MCObjectStreamer {
34 virtual void EmitInstToData(const MCInst &Inst);
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 EmitThumbFunc(MCSymbol *Func);
50 virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
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 assert(0 && "macho doesn't support this directive");
58 virtual void EmitCOFFSymbolStorageClass(int StorageClass) {
59 assert(0 && "macho doesn't support this directive");
61 virtual void EmitCOFFSymbolType(int Type) {
62 assert(0 && "macho doesn't support this directive");
64 virtual void EndCOFFSymbolDef() {
65 assert(0 && "macho doesn't support this directive");
67 virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
68 assert(0 && "macho doesn't support this directive");
70 virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
71 assert(0 && "macho doesn't support this directive");
73 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
74 unsigned Size = 0, unsigned ByteAlignment = 0);
75 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
76 uint64_t Size, unsigned ByteAlignment = 0);
77 virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
78 virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
79 unsigned ValueSize = 1,
80 unsigned MaxBytesToEmit = 0);
81 virtual void EmitCodeAlignment(unsigned ByteAlignment,
82 unsigned MaxBytesToEmit = 0);
84 virtual void EmitFileDirective(StringRef Filename) {
85 // FIXME: Just ignore the .file; it isn't important enough to fail the
88 //report_fatal_error("unsupported directive: '.file'");
91 virtual void Finish();
96 } // end anonymous namespace.
98 void MCMachOStreamer::InitSections() {
99 SwitchSection(getContext().getMachOSection("__TEXT", "__text",
100 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
101 0, SectionKind::getText()));
105 void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
106 MCSymbol *EHSymbol) {
108 getAssembler().getOrCreateSymbolData(*Symbol);
110 EmitSymbolAttribute(EHSymbol, MCSA_Global);
111 if (SD.getFlags() & SF_WeakDefinition)
112 EmitSymbolAttribute(EHSymbol, MCSA_WeakDefinition);
113 if (SD.isPrivateExtern())
114 EmitSymbolAttribute(EHSymbol, MCSA_PrivateExtern);
117 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
118 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
120 // isSymbolLinkerVisible uses the section.
121 Symbol->setSection(*getCurrentSection());
122 // We have to create a new fragment if this is an atom defining symbol,
123 // fragments cannot span atoms.
124 if (getAssembler().isSymbolLinkerVisible(*Symbol))
125 new MCDataFragment(getCurrentSectionData());
127 MCObjectStreamer::EmitLabel(Symbol);
129 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
130 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
131 // to clear the weak reference and weak definition bits too, but the
132 // implementation was buggy. For now we just try to match 'as', for
135 // FIXME: Cleanup this code, these bits should be emitted based on semantic
136 // properties, not on the order of definition, etc.
137 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
140 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
141 // Let the target do whatever target specific stuff it needs to do.
142 getAssembler().getBackend().HandleAssemblerFlag(Flag);
143 // Do any generic stuff we need to do.
145 case MCAF_SyntaxUnified: return; // no-op here.
146 case MCAF_Code16: return; // Change parsing mode; no-op here.
147 case MCAF_Code32: return; // Change parsing mode; no-op here.
148 case MCAF_Code64: return; // Change parsing mode; no-op here.
149 case MCAF_SubsectionsViaSymbols:
150 getAssembler().setSubsectionsViaSymbols(true);
153 llvm_unreachable("invalid assembler flag!");
157 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
158 // FIXME: Flag the function ISA as thumb with DW_AT_APPLE_isa.
160 // Remember that the function is a thumb function. Fixup and relocation
161 // values will need adjusted.
162 getAssembler().setIsThumbFunc(Symbol);
164 // Mark the thumb bit on the symbol.
165 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
166 SD.setFlags(SD.getFlags() | SF_ThumbFunc);
169 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
170 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
172 // FIXME: Lift context changes into super class.
173 getAssembler().getOrCreateSymbolData(*Symbol);
174 Symbol->setVariableValue(AddValueSymbols(Value));
177 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
178 MCSymbolAttr Attribute) {
179 // Indirect symbols are handled differently, to match how 'as' handles
180 // them. This makes writing matching .o files easier.
181 if (Attribute == MCSA_IndirectSymbol) {
182 // Note that we intentionally cannot use the symbol data here; this is
183 // important for matching the string table that 'as' generates.
184 IndirectSymbolData ISD;
186 ISD.SectionData = getCurrentSectionData();
187 getAssembler().getIndirectSymbols().push_back(ISD);
191 // Adding a symbol attribute always introduces the symbol, note that an
192 // important side effect of calling getOrCreateSymbolData here is to register
193 // the symbol with the assembler.
194 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
196 // The implementation of symbol attributes is designed to match 'as', but it
197 // leaves much to desired. It doesn't really make sense to arbitrarily add and
198 // remove flags, but 'as' allows this (in particular, see .desc).
200 // In the future it might be worth trying to make these operations more well
204 case MCSA_ELF_TypeFunction:
205 case MCSA_ELF_TypeIndFunction:
206 case MCSA_ELF_TypeObject:
207 case MCSA_ELF_TypeTLS:
208 case MCSA_ELF_TypeCommon:
209 case MCSA_ELF_TypeNoType:
210 case MCSA_ELF_TypeGnuUniqueObject:
212 case MCSA_IndirectSymbol:
217 assert(0 && "Invalid symbol attribute for Mach-O!");
221 SD.setExternal(true);
222 // This effectively clears the undefined lazy bit, in Darwin 'as', although
223 // it isn't very consistent because it implements this as part of symbol
226 // FIXME: Cleanup this code, these bits should be emitted based on semantic
227 // properties, not on the order of definition, etc.
228 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
231 case MCSA_LazyReference:
232 // FIXME: This requires -dynamic.
233 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
234 if (Symbol->isUndefined())
235 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
238 // Since .reference sets the no dead strip bit, it is equivalent to
239 // .no_dead_strip in practice.
241 case MCSA_NoDeadStrip:
242 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
245 case MCSA_SymbolResolver:
246 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
249 case MCSA_PrivateExtern:
250 SD.setExternal(true);
251 SD.setPrivateExtern(true);
254 case MCSA_WeakReference:
255 // FIXME: This requires -dynamic.
256 if (Symbol->isUndefined())
257 SD.setFlags(SD.getFlags() | SF_WeakReference);
260 case MCSA_WeakDefinition:
261 // FIXME: 'as' enforces that this is defined and global. The manual claims
262 // it has to be in a coalesced section, but this isn't enforced.
263 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
266 case MCSA_WeakDefAutoPrivate:
267 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
272 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
273 // Encode the 'desc' value into the lowest implementation defined bits.
274 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
275 "Invalid .desc value!");
276 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
277 DescValue & SF_DescFlagsMask);
280 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
281 unsigned ByteAlignment) {
282 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
283 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
285 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
286 SD.setExternal(true);
287 SD.setCommon(Size, ByteAlignment);
290 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
291 unsigned Size, unsigned ByteAlignment) {
292 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
294 // The symbol may not be present, which only creates the section.
298 // FIXME: Assert that this section has the zerofill type.
300 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
302 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
304 // Emit an align fragment if necessary.
305 if (ByteAlignment != 1)
306 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
308 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
311 Symbol->setSection(*Section);
313 // Update the maximum alignment on the zero fill section if necessary.
314 if (ByteAlignment > SectData.getAlignment())
315 SectData.setAlignment(ByteAlignment);
318 // This should always be called with the thread local bss section. Like the
319 // .zerofill directive this doesn't actually switch sections on us.
320 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
321 uint64_t Size, unsigned ByteAlignment) {
322 EmitZerofill(Section, Symbol, Size, ByteAlignment);
326 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
327 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
329 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
332 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
333 int64_t Value, unsigned ValueSize,
334 unsigned MaxBytesToEmit) {
335 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
337 if (MaxBytesToEmit == 0)
338 MaxBytesToEmit = ByteAlignment;
339 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
340 getCurrentSectionData());
342 // Update the maximum alignment on the current section if necessary.
343 if (ByteAlignment > getCurrentSectionData()->getAlignment())
344 getCurrentSectionData()->setAlignment(ByteAlignment);
347 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
348 unsigned MaxBytesToEmit) {
349 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
351 if (MaxBytesToEmit == 0)
352 MaxBytesToEmit = ByteAlignment;
353 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
354 getCurrentSectionData());
355 F->setEmitNops(true);
357 // Update the maximum alignment on the current section if necessary.
358 if (ByteAlignment > getCurrentSectionData()->getAlignment())
359 getCurrentSectionData()->setAlignment(ByteAlignment);
362 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
363 MCDataFragment *DF = getOrCreateDataFragment();
365 SmallVector<MCFixup, 4> Fixups;
366 SmallString<256> Code;
367 raw_svector_ostream VecOS(Code);
368 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
371 // Add the fixups and data.
372 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
373 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
374 DF->addFixup(Fixups[i]);
376 DF->getContents().append(Code.begin(), Code.end());
379 void MCMachOStreamer::Finish() {
382 // We have to set the fragment atom associations so we can relax properly for
385 // First, scan the symbol table to build a lookup table from fragments to
387 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
388 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
389 ie = getAssembler().symbol_end(); it != ie; ++it) {
390 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
392 // An atom defining symbol should never be internal to a fragment.
393 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
394 DefiningSymbolMap[it->getFragment()] = it;
398 // Set the fragment atom associations by tracking the last seen atom defining
400 for (MCAssembler::iterator it = getAssembler().begin(),
401 ie = getAssembler().end(); it != ie; ++it) {
402 MCSymbolData *CurrentAtom = 0;
403 for (MCSectionData::iterator it2 = it->begin(),
404 ie2 = it->end(); it2 != ie2; ++it2) {
405 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
407 it2->setAtom(CurrentAtom);
411 this->MCObjectStreamer::Finish();
414 MCStreamer *llvm::createMachOStreamer(MCContext &Context, MCAsmBackend &MAB,
415 raw_ostream &OS, MCCodeEmitter *CE,
417 MCMachOStreamer *S = new MCMachOStreamer(Context, MAB, OS, CE);
419 S->getAssembler().setRelaxAll(true);