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/Support/Dwarf.h"
24 #include "llvm/Support/ErrorHandling.h"
25 #include "llvm/Support/raw_ostream.h"
26 #include "llvm/Target/TargetAsmBackend.h"
32 class MCMachOStreamer : public MCObjectStreamer {
34 virtual void EmitInstToFragment(const MCInst &Inst);
35 virtual void EmitInstToData(const MCInst &Inst);
38 MCMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
39 raw_ostream &OS, MCCodeEmitter *Emitter)
40 : MCObjectStreamer(Context, TAB, OS, Emitter, true) {}
42 /// @name MCStreamer Interface
45 virtual void InitSections();
46 virtual void EmitLabel(MCSymbol *Symbol);
47 virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
48 virtual void EmitThumbFunc(MCSymbol *Func);
49 virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
50 virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
51 virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
52 virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
53 unsigned ByteAlignment);
54 virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {
55 assert(0 && "macho doesn't support this directive");
57 virtual void EmitCOFFSymbolStorageClass(int StorageClass) {
58 assert(0 && "macho doesn't support this directive");
60 virtual void EmitCOFFSymbolType(int Type) {
61 assert(0 && "macho doesn't support this directive");
63 virtual void EndCOFFSymbolDef() {
64 assert(0 && "macho doesn't support this directive");
66 virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
67 assert(0 && "macho doesn't support this directive");
69 virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
70 assert(0 && "macho doesn't support this directive");
72 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
73 unsigned Size = 0, unsigned ByteAlignment = 0);
74 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
75 uint64_t Size, unsigned ByteAlignment = 0);
76 virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
77 virtual void EmitValue(const MCExpr *Value, unsigned Size,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);
83 virtual void EmitValueToOffset(const MCExpr *Offset,
84 unsigned char Value = 0);
86 virtual void EmitFileDirective(StringRef Filename) {
87 // FIXME: Just ignore the .file; it isn't important enough to fail the
90 //report_fatal_error("unsupported directive: '.file'");
93 virtual void Finish();
98 } // end anonymous namespace.
100 void MCMachOStreamer::InitSections() {
101 SwitchSection(getContext().getMachOSection("__TEXT", "__text",
102 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
103 0, SectionKind::getText()));
107 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
108 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
110 // We have to create a new fragment if this is an atom defining symbol,
111 // fragments cannot span atoms.
112 if (getAssembler().isSymbolLinkerVisible(SD.getSymbol()))
113 new MCDataFragment(getCurrentSectionData());
115 MCObjectStreamer::EmitLabel(Symbol);
117 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
118 // to clear the weak reference and weak definition bits too, but the
119 // implementation was buggy. For now we just try to match 'as', for
122 // FIXME: Cleanup this code, these bits should be emitted based on semantic
123 // properties, not on the order of definition, etc.
124 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
127 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
129 case MCAF_SyntaxUnified: return; // no-op here.
130 case MCAF_Code16: return; // no-op here.
131 case MCAF_Code32: return; // no-op here.
132 case MCAF_SubsectionsViaSymbols:
133 getAssembler().setSubsectionsViaSymbols(true);
136 llvm_unreachable("invalid assembler flag!");
140 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Func) {
141 // FIXME: Flag the function ISA as thumb with DW_AT_APPLE_isa.
144 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
145 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
147 // FIXME: Lift context changes into super class.
148 getAssembler().getOrCreateSymbolData(*Symbol);
149 Symbol->setVariableValue(AddValueSymbols(Value));
152 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
153 MCSymbolAttr Attribute) {
154 // Indirect symbols are handled differently, to match how 'as' handles
155 // them. This makes writing matching .o files easier.
156 if (Attribute == MCSA_IndirectSymbol) {
157 // Note that we intentionally cannot use the symbol data here; this is
158 // important for matching the string table that 'as' generates.
159 IndirectSymbolData ISD;
161 ISD.SectionData = getCurrentSectionData();
162 getAssembler().getIndirectSymbols().push_back(ISD);
166 // Adding a symbol attribute always introduces the symbol, note that an
167 // important side effect of calling getOrCreateSymbolData here is to register
168 // the symbol with the assembler.
169 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
171 // The implementation of symbol attributes is designed to match 'as', but it
172 // leaves much to desired. It doesn't really make sense to arbitrarily add and
173 // remove flags, but 'as' allows this (in particular, see .desc).
175 // In the future it might be worth trying to make these operations more well
179 case MCSA_ELF_TypeFunction:
180 case MCSA_ELF_TypeIndFunction:
181 case MCSA_ELF_TypeObject:
182 case MCSA_ELF_TypeTLS:
183 case MCSA_ELF_TypeCommon:
184 case MCSA_ELF_TypeNoType:
185 case MCSA_ELF_TypeGnuUniqueObject:
186 case MCSA_IndirectSymbol:
192 assert(0 && "Invalid symbol attribute for Mach-O!");
196 SD.setExternal(true);
197 // This effectively clears the undefined lazy bit, in Darwin 'as', although
198 // it isn't very consistent because it implements this as part of symbol
201 // FIXME: Cleanup this code, these bits should be emitted based on semantic
202 // properties, not on the order of definition, etc.
203 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
206 case MCSA_LazyReference:
207 // FIXME: This requires -dynamic.
208 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
209 if (Symbol->isUndefined())
210 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
213 // Since .reference sets the no dead strip bit, it is equivalent to
214 // .no_dead_strip in practice.
216 case MCSA_NoDeadStrip:
217 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
220 case MCSA_SymbolResolver:
221 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
224 case MCSA_PrivateExtern:
225 SD.setExternal(true);
226 SD.setPrivateExtern(true);
229 case MCSA_WeakReference:
230 // FIXME: This requires -dynamic.
231 if (Symbol->isUndefined())
232 SD.setFlags(SD.getFlags() | SF_WeakReference);
235 case MCSA_WeakDefinition:
236 // FIXME: 'as' enforces that this is defined and global. The manual claims
237 // it has to be in a coalesced section, but this isn't enforced.
238 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
241 case MCSA_WeakDefAutoPrivate:
242 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
247 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
248 // Encode the 'desc' value into the lowest implementation defined bits.
249 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
250 "Invalid .desc value!");
251 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
252 DescValue & SF_DescFlagsMask);
255 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
256 unsigned ByteAlignment) {
257 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
258 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
260 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
261 SD.setExternal(true);
262 SD.setCommon(Size, ByteAlignment);
265 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
266 unsigned Size, unsigned ByteAlignment) {
267 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
269 // The symbol may not be present, which only creates the section.
273 // FIXME: Assert that this section has the zerofill type.
275 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
277 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
279 // Emit an align fragment if necessary.
280 if (ByteAlignment != 1)
281 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
283 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
286 Symbol->setSection(*Section);
288 // Update the maximum alignment on the zero fill section if necessary.
289 if (ByteAlignment > SectData.getAlignment())
290 SectData.setAlignment(ByteAlignment);
293 // This should always be called with the thread local bss section. Like the
294 // .zerofill directive this doesn't actually switch sections on us.
295 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
296 uint64_t Size, unsigned ByteAlignment) {
297 EmitZerofill(Section, Symbol, Size, ByteAlignment);
301 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
302 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
304 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
307 void MCMachOStreamer::EmitValue(const MCExpr *Value, unsigned Size,
308 unsigned AddrSpace) {
309 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
311 MCDataFragment *DF = getOrCreateDataFragment();
313 // Avoid fixups when possible.
315 if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) {
316 // FIXME: Endianness assumption.
317 for (unsigned i = 0; i != Size; ++i)
318 DF->getContents().push_back(uint8_t(AbsValue >> (i * 8)));
320 DF->addFixup(MCFixup::Create(DF->getContents().size(),
321 AddValueSymbols(Value),
322 MCFixup::getKindForSize(Size, false)));
323 DF->getContents().resize(DF->getContents().size() + Size, 0);
327 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
328 int64_t Value, unsigned ValueSize,
329 unsigned MaxBytesToEmit) {
330 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
332 if (MaxBytesToEmit == 0)
333 MaxBytesToEmit = ByteAlignment;
334 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
335 getCurrentSectionData());
337 // Update the maximum alignment on the current section if necessary.
338 if (ByteAlignment > getCurrentSectionData()->getAlignment())
339 getCurrentSectionData()->setAlignment(ByteAlignment);
342 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
343 unsigned MaxBytesToEmit) {
344 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
346 if (MaxBytesToEmit == 0)
347 MaxBytesToEmit = ByteAlignment;
348 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
349 getCurrentSectionData());
350 F->setEmitNops(true);
352 // Update the maximum alignment on the current section if necessary.
353 if (ByteAlignment > getCurrentSectionData()->getAlignment())
354 getCurrentSectionData()->setAlignment(ByteAlignment);
357 void MCMachOStreamer::EmitValueToOffset(const MCExpr *Offset,
358 unsigned char Value) {
359 new MCOrgFragment(*Offset, Value, getCurrentSectionData());
362 void MCMachOStreamer::EmitInstToFragment(const MCInst &Inst) {
363 MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
365 // Add the fixups and data.
367 // FIXME: Revisit this design decision when relaxation is done, we may be
368 // able to get away with not storing any extra data in the MCInst.
369 SmallVector<MCFixup, 4> Fixups;
370 SmallString<256> Code;
371 raw_svector_ostream VecOS(Code);
372 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
375 IF->getCode() = Code;
376 IF->getFixups() = Fixups;
379 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
380 MCDataFragment *DF = getOrCreateDataFragment();
382 SmallVector<MCFixup, 4> Fixups;
383 SmallString<256> Code;
384 raw_svector_ostream VecOS(Code);
385 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
388 // Add the fixups and data.
389 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
390 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
391 DF->addFixup(Fixups[i]);
393 DF->getContents().append(Code.begin(), Code.end());
396 void MCMachOStreamer::Finish() {
397 // Dump out the dwarf file & directory tables and line tables.
398 if (getContext().hasDwarfFiles()) {
399 const MCSection *DwarfLineSection = getContext().getMachOSection("__DWARF",
401 MCSectionMachO::S_ATTR_DEBUG,
402 0, SectionKind::getDataRelLocal());
404 getAssembler().getOrCreateSectionData(*DwarfLineSection);
405 int PointerSize = getAssembler().getBackend().getPointerSize();
406 MCDwarfFileTable::Emit(this, DwarfLineSection, &DLS, PointerSize);
409 // We have to set the fragment atom associations so we can relax properly for
412 // First, scan the symbol table to build a lookup table from fragments to
414 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
415 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
416 ie = getAssembler().symbol_end(); it != ie; ++it) {
417 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
419 // An atom defining symbol should never be internal to a fragment.
420 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
421 DefiningSymbolMap[it->getFragment()] = it;
425 // Set the fragment atom associations by tracking the last seen atom defining
427 for (MCAssembler::iterator it = getAssembler().begin(),
428 ie = getAssembler().end(); it != ie; ++it) {
429 MCSymbolData *CurrentAtom = 0;
430 for (MCSectionData::iterator it2 = it->begin(),
431 ie2 = it->end(); it2 != ie2; ++it2) {
432 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
434 it2->setAtom(CurrentAtom);
438 this->MCObjectStreamer::Finish();
441 MCStreamer *llvm::createMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
442 raw_ostream &OS, MCCodeEmitter *CE,
444 MCMachOStreamer *S = new MCMachOStreamer(Context, TAB, OS, CE);
446 S->getAssembler().setRelaxAll(true);