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 unsigned ByteAlignment) {
72 assert(0 && "macho doesn't support this directive");
74 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
75 unsigned Size = 0, unsigned ByteAlignment = 0);
76 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
77 uint64_t Size, unsigned ByteAlignment = 0);
78 virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
79 virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
80 unsigned ValueSize = 1,
81 unsigned MaxBytesToEmit = 0);
82 virtual void EmitCodeAlignment(unsigned ByteAlignment,
83 unsigned MaxBytesToEmit = 0);
85 virtual void EmitFileDirective(StringRef Filename) {
86 // FIXME: Just ignore the .file; it isn't important enough to fail the
89 //report_fatal_error("unsupported directive: '.file'");
92 virtual void FinishImpl();
97 } // end anonymous namespace.
99 void MCMachOStreamer::InitSections() {
100 SwitchSection(getContext().getMachOSection("__TEXT", "__text",
101 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
102 0, SectionKind::getText()));
106 void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
107 MCSymbol *EHSymbol) {
109 getAssembler().getOrCreateSymbolData(*Symbol);
111 EmitSymbolAttribute(EHSymbol, MCSA_Global);
112 if (SD.getFlags() & SF_WeakDefinition)
113 EmitSymbolAttribute(EHSymbol, MCSA_WeakDefinition);
114 if (SD.isPrivateExtern())
115 EmitSymbolAttribute(EHSymbol, MCSA_PrivateExtern);
118 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
119 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
121 // isSymbolLinkerVisible uses the section.
122 Symbol->setSection(*getCurrentSection());
123 // We have to create a new fragment if this is an atom defining symbol,
124 // fragments cannot span atoms.
125 if (getAssembler().isSymbolLinkerVisible(*Symbol))
126 new MCDataFragment(getCurrentSectionData());
128 MCObjectStreamer::EmitLabel(Symbol);
130 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
131 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
132 // to clear the weak reference and weak definition bits too, but the
133 // implementation was buggy. For now we just try to match 'as', for
136 // FIXME: Cleanup this code, these bits should be emitted based on semantic
137 // properties, not on the order of definition, etc.
138 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
141 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
142 // Let the target do whatever target specific stuff it needs to do.
143 getAssembler().getBackend().handleAssemblerFlag(Flag);
144 // Do any generic stuff we need to do.
146 case MCAF_SyntaxUnified: return; // no-op here.
147 case MCAF_Code16: return; // Change parsing mode; no-op here.
148 case MCAF_Code32: return; // Change parsing mode; no-op here.
149 case MCAF_Code64: return; // Change parsing mode; no-op here.
150 case MCAF_SubsectionsViaSymbols:
151 getAssembler().setSubsectionsViaSymbols(true);
156 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
157 // Remember that the function is a thumb function. Fixup and relocation
158 // values will need adjusted.
159 getAssembler().setIsThumbFunc(Symbol);
161 // Mark the thumb bit on the symbol.
162 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
163 SD.setFlags(SD.getFlags() | SF_ThumbFunc);
166 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
167 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
169 // FIXME: Lift context changes into super class.
170 getAssembler().getOrCreateSymbolData(*Symbol);
171 Symbol->setVariableValue(AddValueSymbols(Value));
174 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
175 MCSymbolAttr Attribute) {
176 // Indirect symbols are handled differently, to match how 'as' handles
177 // them. This makes writing matching .o files easier.
178 if (Attribute == MCSA_IndirectSymbol) {
179 // Note that we intentionally cannot use the symbol data here; this is
180 // important for matching the string table that 'as' generates.
181 IndirectSymbolData ISD;
183 ISD.SectionData = getCurrentSectionData();
184 getAssembler().getIndirectSymbols().push_back(ISD);
188 // Adding a symbol attribute always introduces the symbol, note that an
189 // important side effect of calling getOrCreateSymbolData here is to register
190 // the symbol with the assembler.
191 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
193 // The implementation of symbol attributes is designed to match 'as', but it
194 // leaves much to desired. It doesn't really make sense to arbitrarily add and
195 // remove flags, but 'as' allows this (in particular, see .desc).
197 // In the future it might be worth trying to make these operations more well
201 case MCSA_ELF_TypeFunction:
202 case MCSA_ELF_TypeIndFunction:
203 case MCSA_ELF_TypeObject:
204 case MCSA_ELF_TypeTLS:
205 case MCSA_ELF_TypeCommon:
206 case MCSA_ELF_TypeNoType:
207 case MCSA_ELF_TypeGnuUniqueObject:
209 case MCSA_IndirectSymbol:
214 assert(0 && "Invalid symbol attribute for Mach-O!");
218 SD.setExternal(true);
219 // This effectively clears the undefined lazy bit, in Darwin 'as', although
220 // it isn't very consistent because it implements this as part of symbol
223 // FIXME: Cleanup this code, these bits should be emitted based on semantic
224 // properties, not on the order of definition, etc.
225 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
228 case MCSA_LazyReference:
229 // FIXME: This requires -dynamic.
230 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
231 if (Symbol->isUndefined())
232 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
235 // Since .reference sets the no dead strip bit, it is equivalent to
236 // .no_dead_strip in practice.
238 case MCSA_NoDeadStrip:
239 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
242 case MCSA_SymbolResolver:
243 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
246 case MCSA_PrivateExtern:
247 SD.setExternal(true);
248 SD.setPrivateExtern(true);
251 case MCSA_WeakReference:
252 // FIXME: This requires -dynamic.
253 if (Symbol->isUndefined())
254 SD.setFlags(SD.getFlags() | SF_WeakReference);
257 case MCSA_WeakDefinition:
258 // FIXME: 'as' enforces that this is defined and global. The manual claims
259 // it has to be in a coalesced section, but this isn't enforced.
260 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
263 case MCSA_WeakDefAutoPrivate:
264 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
269 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
270 // Encode the 'desc' value into the lowest implementation defined bits.
271 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
272 "Invalid .desc value!");
273 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
274 DescValue & SF_DescFlagsMask);
277 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
278 unsigned ByteAlignment) {
279 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
280 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
282 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
283 SD.setExternal(true);
284 SD.setCommon(Size, ByteAlignment);
287 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
288 unsigned Size, unsigned ByteAlignment) {
289 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
291 // The symbol may not be present, which only creates the section.
295 // FIXME: Assert that this section has the zerofill type.
297 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
299 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
301 // Emit an align fragment if necessary.
302 if (ByteAlignment != 1)
303 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
305 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
308 Symbol->setSection(*Section);
310 // Update the maximum alignment on the zero fill section if necessary.
311 if (ByteAlignment > SectData.getAlignment())
312 SectData.setAlignment(ByteAlignment);
315 // This should always be called with the thread local bss section. Like the
316 // .zerofill directive this doesn't actually switch sections on us.
317 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
318 uint64_t Size, unsigned ByteAlignment) {
319 EmitZerofill(Section, Symbol, Size, ByteAlignment);
323 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
324 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
326 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
329 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
330 int64_t Value, unsigned ValueSize,
331 unsigned MaxBytesToEmit) {
332 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
334 if (MaxBytesToEmit == 0)
335 MaxBytesToEmit = ByteAlignment;
336 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
337 getCurrentSectionData());
339 // Update the maximum alignment on the current section if necessary.
340 if (ByteAlignment > getCurrentSectionData()->getAlignment())
341 getCurrentSectionData()->setAlignment(ByteAlignment);
344 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
345 unsigned MaxBytesToEmit) {
346 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
348 if (MaxBytesToEmit == 0)
349 MaxBytesToEmit = ByteAlignment;
350 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
351 getCurrentSectionData());
352 F->setEmitNops(true);
354 // Update the maximum alignment on the current section if necessary.
355 if (ByteAlignment > getCurrentSectionData()->getAlignment())
356 getCurrentSectionData()->setAlignment(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);