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 // TODO: This is almost exactly the same as WinCOFFStreamer. Consider merging
109 // into MCObjectStreamer.
110 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
111 assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
112 assert(CurSection && "Cannot emit before setting section!");
114 Symbol->setSection(*CurSection);
116 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
118 // We have to create a new fragment if this is an atom defining symbol,
119 // fragments cannot span atoms.
120 if (getAssembler().isSymbolLinkerVisible(SD.getSymbol()))
121 new MCDataFragment(getCurrentSectionData());
123 // FIXME: This is wasteful, we don't necessarily need to create a data
124 // fragment. Instead, we should mark the symbol as pointing into the data
125 // fragment if it exists, otherwise we should just queue the label and set its
126 // fragment pointer when we emit the next fragment.
127 MCDataFragment *F = getOrCreateDataFragment();
128 assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
130 SD.setOffset(F->getContents().size());
132 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
133 // to clear the weak reference and weak definition bits too, but the
134 // implementation was buggy. For now we just try to match 'as', for
137 // FIXME: Cleanup this code, these bits should be emitted based on semantic
138 // properties, not on the order of definition, etc.
139 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
142 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
144 case MCAF_SyntaxUnified: return; // no-op here.
145 case MCAF_Code16: return; // no-op here.
146 case MCAF_Code32: return; // no-op here.
147 case MCAF_SubsectionsViaSymbols:
148 getAssembler().setSubsectionsViaSymbols(true);
151 llvm_unreachable("invalid assembler flag!");
155 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Func) {
156 // FIXME: Flag the function ISA as thumb with DW_AT_APPLE_isa.
159 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
160 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
162 // FIXME: Lift context changes into super class.
163 getAssembler().getOrCreateSymbolData(*Symbol);
164 Symbol->setVariableValue(AddValueSymbols(Value));
167 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
168 MCSymbolAttr Attribute) {
169 // Indirect symbols are handled differently, to match how 'as' handles
170 // them. This makes writing matching .o files easier.
171 if (Attribute == MCSA_IndirectSymbol) {
172 // Note that we intentionally cannot use the symbol data here; this is
173 // important for matching the string table that 'as' generates.
174 IndirectSymbolData ISD;
176 ISD.SectionData = getCurrentSectionData();
177 getAssembler().getIndirectSymbols().push_back(ISD);
181 // Adding a symbol attribute always introduces the symbol, note that an
182 // important side effect of calling getOrCreateSymbolData here is to register
183 // the symbol with the assembler.
184 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
186 // The implementation of symbol attributes is designed to match 'as', but it
187 // leaves much to desired. It doesn't really make sense to arbitrarily add and
188 // remove flags, but 'as' allows this (in particular, see .desc).
190 // In the future it might be worth trying to make these operations more well
194 case MCSA_ELF_TypeFunction:
195 case MCSA_ELF_TypeIndFunction:
196 case MCSA_ELF_TypeObject:
197 case MCSA_ELF_TypeTLS:
198 case MCSA_ELF_TypeCommon:
199 case MCSA_ELF_TypeNoType:
200 case MCSA_ELF_TypeGnuUniqueObject:
201 case MCSA_IndirectSymbol:
207 assert(0 && "Invalid symbol attribute for Mach-O!");
211 SD.setExternal(true);
212 // This effectively clears the undefined lazy bit, in Darwin 'as', although
213 // it isn't very consistent because it implements this as part of symbol
216 // FIXME: Cleanup this code, these bits should be emitted based on semantic
217 // properties, not on the order of definition, etc.
218 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
221 case MCSA_LazyReference:
222 // FIXME: This requires -dynamic.
223 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
224 if (Symbol->isUndefined())
225 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
228 // Since .reference sets the no dead strip bit, it is equivalent to
229 // .no_dead_strip in practice.
231 case MCSA_NoDeadStrip:
232 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
235 case MCSA_SymbolResolver:
236 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
239 case MCSA_PrivateExtern:
240 SD.setExternal(true);
241 SD.setPrivateExtern(true);
244 case MCSA_WeakReference:
245 // FIXME: This requires -dynamic.
246 if (Symbol->isUndefined())
247 SD.setFlags(SD.getFlags() | SF_WeakReference);
250 case MCSA_WeakDefinition:
251 // FIXME: 'as' enforces that this is defined and global. The manual claims
252 // it has to be in a coalesced section, but this isn't enforced.
253 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
256 case MCSA_WeakDefAutoPrivate:
257 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
262 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
263 // Encode the 'desc' value into the lowest implementation defined bits.
264 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
265 "Invalid .desc value!");
266 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
267 DescValue & SF_DescFlagsMask);
270 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
271 unsigned ByteAlignment) {
272 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
273 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
275 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
276 SD.setExternal(true);
277 SD.setCommon(Size, ByteAlignment);
280 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
281 unsigned Size, unsigned ByteAlignment) {
282 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
284 // The symbol may not be present, which only creates the section.
288 // FIXME: Assert that this section has the zerofill type.
290 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
292 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
294 // Emit an align fragment if necessary.
295 if (ByteAlignment != 1)
296 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
298 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
301 Symbol->setSection(*Section);
303 // Update the maximum alignment on the zero fill section if necessary.
304 if (ByteAlignment > SectData.getAlignment())
305 SectData.setAlignment(ByteAlignment);
308 // This should always be called with the thread local bss section. Like the
309 // .zerofill directive this doesn't actually switch sections on us.
310 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
311 uint64_t Size, unsigned ByteAlignment) {
312 EmitZerofill(Section, Symbol, Size, ByteAlignment);
316 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
317 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
319 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
322 void MCMachOStreamer::EmitValue(const MCExpr *Value, unsigned Size,
323 unsigned AddrSpace) {
324 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
326 MCDataFragment *DF = getOrCreateDataFragment();
328 // Avoid fixups when possible.
330 if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) {
331 // FIXME: Endianness assumption.
332 for (unsigned i = 0; i != Size; ++i)
333 DF->getContents().push_back(uint8_t(AbsValue >> (i * 8)));
335 DF->addFixup(MCFixup::Create(DF->getContents().size(),
336 AddValueSymbols(Value),
337 MCFixup::getKindForSize(Size, false)));
338 DF->getContents().resize(DF->getContents().size() + Size, 0);
342 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
343 int64_t Value, unsigned ValueSize,
344 unsigned MaxBytesToEmit) {
345 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
347 if (MaxBytesToEmit == 0)
348 MaxBytesToEmit = ByteAlignment;
349 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
350 getCurrentSectionData());
352 // Update the maximum alignment on the current section if necessary.
353 if (ByteAlignment > getCurrentSectionData()->getAlignment())
354 getCurrentSectionData()->setAlignment(ByteAlignment);
357 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
358 unsigned MaxBytesToEmit) {
359 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
361 if (MaxBytesToEmit == 0)
362 MaxBytesToEmit = ByteAlignment;
363 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
364 getCurrentSectionData());
365 F->setEmitNops(true);
367 // Update the maximum alignment on the current section if necessary.
368 if (ByteAlignment > getCurrentSectionData()->getAlignment())
369 getCurrentSectionData()->setAlignment(ByteAlignment);
372 void MCMachOStreamer::EmitValueToOffset(const MCExpr *Offset,
373 unsigned char Value) {
374 new MCOrgFragment(*Offset, Value, getCurrentSectionData());
377 void MCMachOStreamer::EmitInstToFragment(const MCInst &Inst) {
378 MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
380 // Add the fixups and data.
382 // FIXME: Revisit this design decision when relaxation is done, we may be
383 // able to get away with not storing any extra data in the MCInst.
384 SmallVector<MCFixup, 4> Fixups;
385 SmallString<256> Code;
386 raw_svector_ostream VecOS(Code);
387 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
390 IF->getCode() = Code;
391 IF->getFixups() = Fixups;
394 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
395 MCDataFragment *DF = getOrCreateDataFragment();
397 SmallVector<MCFixup, 4> Fixups;
398 SmallString<256> Code;
399 raw_svector_ostream VecOS(Code);
400 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
403 // Add the fixups and data.
404 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
405 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
406 DF->addFixup(Fixups[i]);
408 DF->getContents().append(Code.begin(), Code.end());
411 void MCMachOStreamer::Finish() {
412 // Dump out the dwarf file & directory tables and line tables.
413 if (getContext().hasDwarfFiles()) {
414 const MCSection *DwarfLineSection = getContext().getMachOSection("__DWARF",
416 MCSectionMachO::S_ATTR_DEBUG,
417 0, SectionKind::getDataRelLocal());
419 getAssembler().getOrCreateSectionData(*DwarfLineSection);
420 int PointerSize = getAssembler().getBackend().getPointerSize();
421 MCDwarfFileTable::Emit(this, DwarfLineSection, &DLS, PointerSize);
424 // We have to set the fragment atom associations so we can relax properly for
427 // First, scan the symbol table to build a lookup table from fragments to
429 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
430 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
431 ie = getAssembler().symbol_end(); it != ie; ++it) {
432 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
434 // An atom defining symbol should never be internal to a fragment.
435 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
436 DefiningSymbolMap[it->getFragment()] = it;
440 // Set the fragment atom associations by tracking the last seen atom defining
442 for (MCAssembler::iterator it = getAssembler().begin(),
443 ie = getAssembler().end(); it != ie; ++it) {
444 MCSymbolData *CurrentAtom = 0;
445 for (MCSectionData::iterator it2 = it->begin(),
446 ie2 = it->end(); it2 != ie2; ++it2) {
447 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
449 it2->setAtom(CurrentAtom);
453 this->MCObjectStreamer::Finish();
456 MCStreamer *llvm::createMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
457 raw_ostream &OS, MCCodeEmitter *CE,
459 MCMachOStreamer *S = new MCMachOStreamer(Context, TAB, OS, CE);
461 S->getAssembler().setRelaxAll(true);