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 EmitGPRel32Value(const MCExpr *Value) {
79 assert(0 && "macho doesn't support this directive");
81 virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
82 unsigned ValueSize = 1,
83 unsigned MaxBytesToEmit = 0);
84 virtual void EmitCodeAlignment(unsigned ByteAlignment,
85 unsigned MaxBytesToEmit = 0);
86 virtual void EmitValueToOffset(const MCExpr *Offset,
87 unsigned char Value = 0);
89 virtual void EmitFileDirective(StringRef Filename) {
90 // FIXME: Just ignore the .file; it isn't important enough to fail the
93 //report_fatal_error("unsupported directive: '.file'");
96 virtual void Finish();
101 } // end anonymous namespace.
103 void MCMachOStreamer::InitSections() {
104 SwitchSection(getContext().getMachOSection("__TEXT", "__text",
105 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
106 0, SectionKind::getText()));
110 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
111 // TODO: This is almost exactly the same as WinCOFFStreamer. Consider merging
112 // into MCObjectStreamer.
113 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
114 assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
115 assert(CurSection && "Cannot emit before setting section!");
117 Symbol->setSection(*CurSection);
119 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
121 // We have to create a new fragment if this is an atom defining symbol,
122 // fragments cannot span atoms.
123 if (getAssembler().isSymbolLinkerVisible(SD.getSymbol()))
124 new MCDataFragment(getCurrentSectionData());
126 // FIXME: This is wasteful, we don't necessarily need to create a data
127 // fragment. Instead, we should mark the symbol as pointing into the data
128 // fragment if it exists, otherwise we should just queue the label and set its
129 // fragment pointer when we emit the next fragment.
130 MCDataFragment *F = getOrCreateDataFragment();
131 assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
133 SD.setOffset(F->getContents().size());
135 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
136 // to clear the weak reference and weak definition bits too, but the
137 // implementation was buggy. For now we just try to match 'as', for
140 // FIXME: Cleanup this code, these bits should be emitted based on semantic
141 // properties, not on the order of definition, etc.
142 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
145 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
147 case MCAF_SyntaxUnified: return; // no-op here.
148 case MCAF_Code16: return; // no-op here.
149 case MCAF_Code32: return; // no-op here.
150 case MCAF_SubsectionsViaSymbols:
151 getAssembler().setSubsectionsViaSymbols(true);
154 llvm_unreachable("invalid assembler flag!");
158 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Func) {
159 // FIXME: Flag the function ISA as thumb with DW_AT_APPLE_isa.
162 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
163 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
165 // FIXME: Lift context changes into super class.
166 getAssembler().getOrCreateSymbolData(*Symbol);
167 Symbol->setVariableValue(AddValueSymbols(Value));
170 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
171 MCSymbolAttr Attribute) {
172 // Indirect symbols are handled differently, to match how 'as' handles
173 // them. This makes writing matching .o files easier.
174 if (Attribute == MCSA_IndirectSymbol) {
175 // Note that we intentionally cannot use the symbol data here; this is
176 // important for matching the string table that 'as' generates.
177 IndirectSymbolData ISD;
179 ISD.SectionData = getCurrentSectionData();
180 getAssembler().getIndirectSymbols().push_back(ISD);
184 // Adding a symbol attribute always introduces the symbol, note that an
185 // important side effect of calling getOrCreateSymbolData here is to register
186 // the symbol with the assembler.
187 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
189 // The implementation of symbol attributes is designed to match 'as', but it
190 // leaves much to desired. It doesn't really make sense to arbitrarily add and
191 // remove flags, but 'as' allows this (in particular, see .desc).
193 // In the future it might be worth trying to make these operations more well
197 case MCSA_ELF_TypeFunction:
198 case MCSA_ELF_TypeIndFunction:
199 case MCSA_ELF_TypeObject:
200 case MCSA_ELF_TypeTLS:
201 case MCSA_ELF_TypeCommon:
202 case MCSA_ELF_TypeNoType:
203 case MCSA_ELF_TypeGnuUniqueObject:
204 case MCSA_IndirectSymbol:
210 assert(0 && "Invalid symbol attribute for Mach-O!");
214 SD.setExternal(true);
215 // This effectively clears the undefined lazy bit, in Darwin 'as', although
216 // it isn't very consistent because it implements this as part of symbol
219 // FIXME: Cleanup this code, these bits should be emitted based on semantic
220 // properties, not on the order of definition, etc.
221 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
224 case MCSA_LazyReference:
225 // FIXME: This requires -dynamic.
226 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
227 if (Symbol->isUndefined())
228 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
231 // Since .reference sets the no dead strip bit, it is equivalent to
232 // .no_dead_strip in practice.
234 case MCSA_NoDeadStrip:
235 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
238 case MCSA_SymbolResolver:
239 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
242 case MCSA_PrivateExtern:
243 SD.setExternal(true);
244 SD.setPrivateExtern(true);
247 case MCSA_WeakReference:
248 // FIXME: This requires -dynamic.
249 if (Symbol->isUndefined())
250 SD.setFlags(SD.getFlags() | SF_WeakReference);
253 case MCSA_WeakDefinition:
254 // FIXME: 'as' enforces that this is defined and global. The manual claims
255 // it has to be in a coalesced section, but this isn't enforced.
256 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
259 case MCSA_WeakDefAutoPrivate:
260 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
265 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
266 // Encode the 'desc' value into the lowest implementation defined bits.
267 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
268 "Invalid .desc value!");
269 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
270 DescValue & SF_DescFlagsMask);
273 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
274 unsigned ByteAlignment) {
275 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
276 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
278 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
279 SD.setExternal(true);
280 SD.setCommon(Size, ByteAlignment);
283 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
284 unsigned Size, unsigned ByteAlignment) {
285 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
287 // The symbol may not be present, which only creates the section.
291 // FIXME: Assert that this section has the zerofill type.
293 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
295 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
297 // Emit an align fragment if necessary.
298 if (ByteAlignment != 1)
299 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
301 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
304 Symbol->setSection(*Section);
306 // Update the maximum alignment on the zero fill section if necessary.
307 if (ByteAlignment > SectData.getAlignment())
308 SectData.setAlignment(ByteAlignment);
311 // This should always be called with the thread local bss section. Like the
312 // .zerofill directive this doesn't actually switch sections on us.
313 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
314 uint64_t Size, unsigned ByteAlignment) {
315 EmitZerofill(Section, Symbol, Size, ByteAlignment);
319 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
320 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
322 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
325 void MCMachOStreamer::EmitValue(const MCExpr *Value, unsigned Size,
326 unsigned AddrSpace) {
327 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
329 MCDataFragment *DF = getOrCreateDataFragment();
331 // Avoid fixups when possible.
333 if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) {
334 // FIXME: Endianness assumption.
335 for (unsigned i = 0; i != Size; ++i)
336 DF->getContents().push_back(uint8_t(AbsValue >> (i * 8)));
338 DF->addFixup(MCFixup::Create(DF->getContents().size(),
339 AddValueSymbols(Value),
340 MCFixup::getKindForSize(Size)));
341 DF->getContents().resize(DF->getContents().size() + Size, 0);
345 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
346 int64_t Value, unsigned ValueSize,
347 unsigned MaxBytesToEmit) {
348 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
350 if (MaxBytesToEmit == 0)
351 MaxBytesToEmit = ByteAlignment;
352 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
353 getCurrentSectionData());
355 // Update the maximum alignment on the current section if necessary.
356 if (ByteAlignment > getCurrentSectionData()->getAlignment())
357 getCurrentSectionData()->setAlignment(ByteAlignment);
360 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
361 unsigned MaxBytesToEmit) {
362 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
364 if (MaxBytesToEmit == 0)
365 MaxBytesToEmit = ByteAlignment;
366 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
367 getCurrentSectionData());
368 F->setEmitNops(true);
370 // Update the maximum alignment on the current section if necessary.
371 if (ByteAlignment > getCurrentSectionData()->getAlignment())
372 getCurrentSectionData()->setAlignment(ByteAlignment);
375 void MCMachOStreamer::EmitValueToOffset(const MCExpr *Offset,
376 unsigned char Value) {
377 new MCOrgFragment(*Offset, Value, getCurrentSectionData());
380 void MCMachOStreamer::EmitInstToFragment(const MCInst &Inst) {
381 MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
383 // Add the fixups and data.
385 // FIXME: Revisit this design decision when relaxation is done, we may be
386 // able to get away with not storing any extra data in the MCInst.
387 SmallVector<MCFixup, 4> Fixups;
388 SmallString<256> Code;
389 raw_svector_ostream VecOS(Code);
390 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
393 IF->getCode() = Code;
394 IF->getFixups() = Fixups;
397 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
398 MCDataFragment *DF = getOrCreateDataFragment();
400 SmallVector<MCFixup, 4> Fixups;
401 SmallString<256> Code;
402 raw_svector_ostream VecOS(Code);
403 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
406 // Add the fixups and data.
407 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
408 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
409 DF->addFixup(Fixups[i]);
411 DF->getContents().append(Code.begin(), Code.end());
414 void MCMachOStreamer::Finish() {
415 // Dump out the dwarf file & directory tables and line tables.
416 if (getContext().hasDwarfFiles()) {
417 const MCSection *DwarfLineSection = getContext().getMachOSection("__DWARF",
419 MCSectionMachO::S_ATTR_DEBUG,
420 0, SectionKind::getDataRelLocal());
422 getAssembler().getOrCreateSectionData(*DwarfLineSection);
423 int PointerSize = getAssembler().getBackend().getPointerSize();
424 MCDwarfFileTable::Emit(this, DwarfLineSection, &DLS, PointerSize);
427 // We have to set the fragment atom associations so we can relax properly for
430 // First, scan the symbol table to build a lookup table from fragments to
432 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
433 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
434 ie = getAssembler().symbol_end(); it != ie; ++it) {
435 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
437 // An atom defining symbol should never be internal to a fragment.
438 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
439 DefiningSymbolMap[it->getFragment()] = it;
443 // Set the fragment atom associations by tracking the last seen atom defining
445 for (MCAssembler::iterator it = getAssembler().begin(),
446 ie = getAssembler().end(); it != ie; ++it) {
447 MCSymbolData *CurrentAtom = 0;
448 for (MCSectionData::iterator it2 = it->begin(),
449 ie2 = it->end(); it2 != ie2; ++it2) {
450 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
452 it2->setAtom(CurrentAtom);
456 this->MCObjectStreamer::Finish();
459 MCStreamer *llvm::createMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
460 raw_ostream &OS, MCCodeEmitter *CE,
462 MCMachOStreamer *S = new MCMachOStreamer(Context, TAB, OS, CE);
464 S->getAssembler().setRelaxAll(true);