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 EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
78 unsigned ValueSize = 1,
79 unsigned MaxBytesToEmit = 0);
80 virtual void EmitCodeAlignment(unsigned ByteAlignment,
81 unsigned MaxBytesToEmit = 0);
82 virtual void EmitValueToOffset(const MCExpr *Offset,
83 unsigned char Value = 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 Finish();
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::EmitLabel(MCSymbol *Symbol) {
107 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
109 // isSymbolLinkerVisible uses the section.
110 Symbol->setSection(*CurSection);
111 // We have to create a new fragment if this is an atom defining symbol,
112 // fragments cannot span atoms.
113 if (getAssembler().isSymbolLinkerVisible(*Symbol))
114 new MCDataFragment(getCurrentSectionData());
116 MCObjectStreamer::EmitLabel(Symbol);
118 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
119 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
120 // to clear the weak reference and weak definition bits too, but the
121 // implementation was buggy. For now we just try to match 'as', for
124 // FIXME: Cleanup this code, these bits should be emitted based on semantic
125 // properties, not on the order of definition, etc.
126 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
129 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
131 case MCAF_SyntaxUnified: return; // no-op here.
132 case MCAF_Code16: return; // no-op here.
133 case MCAF_Code32: return; // no-op here.
134 case MCAF_SubsectionsViaSymbols:
135 getAssembler().setSubsectionsViaSymbols(true);
138 llvm_unreachable("invalid assembler flag!");
142 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Func) {
143 // FIXME: Flag the function ISA as thumb with DW_AT_APPLE_isa.
146 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
147 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
149 // FIXME: Lift context changes into super class.
150 getAssembler().getOrCreateSymbolData(*Symbol);
151 Symbol->setVariableValue(AddValueSymbols(Value));
154 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
155 MCSymbolAttr Attribute) {
156 // Indirect symbols are handled differently, to match how 'as' handles
157 // them. This makes writing matching .o files easier.
158 if (Attribute == MCSA_IndirectSymbol) {
159 // Note that we intentionally cannot use the symbol data here; this is
160 // important for matching the string table that 'as' generates.
161 IndirectSymbolData ISD;
163 ISD.SectionData = getCurrentSectionData();
164 getAssembler().getIndirectSymbols().push_back(ISD);
168 // Adding a symbol attribute always introduces the symbol, note that an
169 // important side effect of calling getOrCreateSymbolData here is to register
170 // the symbol with the assembler.
171 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
173 // The implementation of symbol attributes is designed to match 'as', but it
174 // leaves much to desired. It doesn't really make sense to arbitrarily add and
175 // remove flags, but 'as' allows this (in particular, see .desc).
177 // In the future it might be worth trying to make these operations more well
181 case MCSA_ELF_TypeFunction:
182 case MCSA_ELF_TypeIndFunction:
183 case MCSA_ELF_TypeObject:
184 case MCSA_ELF_TypeTLS:
185 case MCSA_ELF_TypeCommon:
186 case MCSA_ELF_TypeNoType:
187 case MCSA_ELF_TypeGnuUniqueObject:
188 case MCSA_IndirectSymbol:
194 assert(0 && "Invalid symbol attribute for Mach-O!");
198 SD.setExternal(true);
199 // This effectively clears the undefined lazy bit, in Darwin 'as', although
200 // it isn't very consistent because it implements this as part of symbol
203 // FIXME: Cleanup this code, these bits should be emitted based on semantic
204 // properties, not on the order of definition, etc.
205 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
208 case MCSA_LazyReference:
209 // FIXME: This requires -dynamic.
210 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
211 if (Symbol->isUndefined())
212 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
215 // Since .reference sets the no dead strip bit, it is equivalent to
216 // .no_dead_strip in practice.
218 case MCSA_NoDeadStrip:
219 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
222 case MCSA_SymbolResolver:
223 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
226 case MCSA_PrivateExtern:
227 SD.setExternal(true);
228 SD.setPrivateExtern(true);
231 case MCSA_WeakReference:
232 // FIXME: This requires -dynamic.
233 if (Symbol->isUndefined())
234 SD.setFlags(SD.getFlags() | SF_WeakReference);
237 case MCSA_WeakDefinition:
238 // FIXME: 'as' enforces that this is defined and global. The manual claims
239 // it has to be in a coalesced section, but this isn't enforced.
240 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
243 case MCSA_WeakDefAutoPrivate:
244 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
249 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
250 // Encode the 'desc' value into the lowest implementation defined bits.
251 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
252 "Invalid .desc value!");
253 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
254 DescValue & SF_DescFlagsMask);
257 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
258 unsigned ByteAlignment) {
259 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
260 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
262 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
263 SD.setExternal(true);
264 SD.setCommon(Size, ByteAlignment);
267 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
268 unsigned Size, unsigned ByteAlignment) {
269 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
271 // The symbol may not be present, which only creates the section.
275 // FIXME: Assert that this section has the zerofill type.
277 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
279 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
281 // Emit an align fragment if necessary.
282 if (ByteAlignment != 1)
283 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
285 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
288 Symbol->setSection(*Section);
290 // Update the maximum alignment on the zero fill section if necessary.
291 if (ByteAlignment > SectData.getAlignment())
292 SectData.setAlignment(ByteAlignment);
295 // This should always be called with the thread local bss section. Like the
296 // .zerofill directive this doesn't actually switch sections on us.
297 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
298 uint64_t Size, unsigned ByteAlignment) {
299 EmitZerofill(Section, Symbol, Size, ByteAlignment);
303 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
304 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
306 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
309 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
310 int64_t Value, unsigned ValueSize,
311 unsigned MaxBytesToEmit) {
312 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
314 if (MaxBytesToEmit == 0)
315 MaxBytesToEmit = ByteAlignment;
316 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
317 getCurrentSectionData());
319 // Update the maximum alignment on the current section if necessary.
320 if (ByteAlignment > getCurrentSectionData()->getAlignment())
321 getCurrentSectionData()->setAlignment(ByteAlignment);
324 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
325 unsigned MaxBytesToEmit) {
326 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
328 if (MaxBytesToEmit == 0)
329 MaxBytesToEmit = ByteAlignment;
330 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
331 getCurrentSectionData());
332 F->setEmitNops(true);
334 // Update the maximum alignment on the current section if necessary.
335 if (ByteAlignment > getCurrentSectionData()->getAlignment())
336 getCurrentSectionData()->setAlignment(ByteAlignment);
339 void MCMachOStreamer::EmitValueToOffset(const MCExpr *Offset,
340 unsigned char Value) {
341 new MCOrgFragment(*Offset, Value, getCurrentSectionData());
344 void MCMachOStreamer::EmitInstToFragment(const MCInst &Inst) {
345 MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
347 // Add the fixups and data.
349 // FIXME: Revisit this design decision when relaxation is done, we may be
350 // able to get away with not storing any extra data in the MCInst.
351 SmallVector<MCFixup, 4> Fixups;
352 SmallString<256> Code;
353 raw_svector_ostream VecOS(Code);
354 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
357 IF->getCode() = Code;
358 IF->getFixups() = Fixups;
361 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
362 MCDataFragment *DF = getOrCreateDataFragment();
364 SmallVector<MCFixup, 4> Fixups;
365 SmallString<256> Code;
366 raw_svector_ostream VecOS(Code);
367 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
370 // Add the fixups and data.
371 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
372 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
373 DF->addFixup(Fixups[i]);
375 DF->getContents().append(Code.begin(), Code.end());
378 void MCMachOStreamer::Finish() {
379 // Dump out the dwarf file & directory tables and line tables.
380 if (getContext().hasDwarfFiles()) {
381 const MCSection *DwarfLineSection = getContext().getMachOSection("__DWARF",
383 MCSectionMachO::S_ATTR_DEBUG,
384 0, SectionKind::getDataRelLocal());
386 getAssembler().getOrCreateSectionData(*DwarfLineSection);
387 int PointerSize = getAssembler().getBackend().getPointerSize();
388 MCDwarfFileTable::Emit(this, DwarfLineSection, &DLS, PointerSize);
391 // We have to set the fragment atom associations so we can relax properly for
394 // First, scan the symbol table to build a lookup table from fragments to
396 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
397 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
398 ie = getAssembler().symbol_end(); it != ie; ++it) {
399 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
401 // An atom defining symbol should never be internal to a fragment.
402 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
403 DefiningSymbolMap[it->getFragment()] = it;
407 // Set the fragment atom associations by tracking the last seen atom defining
409 for (MCAssembler::iterator it = getAssembler().begin(),
410 ie = getAssembler().end(); it != ie; ++it) {
411 MCSymbolData *CurrentAtom = 0;
412 for (MCSectionData::iterator it2 = it->begin(),
413 ie2 = it->end(); it2 != ie2; ++it2) {
414 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
416 it2->setAtom(CurrentAtom);
420 this->MCObjectStreamer::Finish();
423 MCStreamer *llvm::createMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
424 raw_ostream &OS, MCCodeEmitter *CE,
426 MCMachOStreamer *S = new MCMachOStreamer(Context, TAB, OS, CE);
428 S->getAssembler().setRelaxAll(true);