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 EmitInstToData(const MCInst &Inst);
37 MCMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
38 raw_ostream &OS, MCCodeEmitter *Emitter)
39 : MCObjectStreamer(Context, TAB, OS, Emitter, true) {}
41 /// @name MCStreamer Interface
44 virtual void InitSections();
45 virtual void EmitLabel(MCSymbol *Symbol);
46 virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
47 virtual void EmitThumbFunc(MCSymbol *Func);
48 virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
49 virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
50 virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
51 virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
52 unsigned ByteAlignment);
53 virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {
54 assert(0 && "macho doesn't support this directive");
56 virtual void EmitCOFFSymbolStorageClass(int StorageClass) {
57 assert(0 && "macho doesn't support this directive");
59 virtual void EmitCOFFSymbolType(int Type) {
60 assert(0 && "macho doesn't support this directive");
62 virtual void EndCOFFSymbolDef() {
63 assert(0 && "macho doesn't support this directive");
65 virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
66 assert(0 && "macho doesn't support this directive");
68 virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
69 assert(0 && "macho doesn't support this directive");
71 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
72 unsigned Size = 0, unsigned ByteAlignment = 0);
73 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
74 uint64_t Size, unsigned ByteAlignment = 0);
75 virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
76 virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
77 unsigned ValueSize = 1,
78 unsigned MaxBytesToEmit = 0);
79 virtual void EmitCodeAlignment(unsigned ByteAlignment,
80 unsigned MaxBytesToEmit = 0);
82 virtual void EmitFileDirective(StringRef Filename) {
83 // FIXME: Just ignore the .file; it isn't important enough to fail the
86 //report_fatal_error("unsupported directive: '.file'");
89 virtual void Finish();
94 } // end anonymous namespace.
96 void MCMachOStreamer::InitSections() {
97 SwitchSection(getContext().getMachOSection("__TEXT", "__text",
98 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
99 0, SectionKind::getText()));
103 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
104 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
106 // isSymbolLinkerVisible uses the section.
107 Symbol->setSection(*CurSection);
108 // We have to create a new fragment if this is an atom defining symbol,
109 // fragments cannot span atoms.
110 if (getAssembler().isSymbolLinkerVisible(*Symbol))
111 new MCDataFragment(getCurrentSectionData());
113 MCObjectStreamer::EmitLabel(Symbol);
115 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
116 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
117 // to clear the weak reference and weak definition bits too, but the
118 // implementation was buggy. For now we just try to match 'as', for
121 // FIXME: Cleanup this code, these bits should be emitted based on semantic
122 // properties, not on the order of definition, etc.
123 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
126 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
128 case MCAF_SyntaxUnified: return; // no-op here.
129 case MCAF_Code16: return; // no-op here.
130 case MCAF_Code32: return; // no-op here.
131 case MCAF_SubsectionsViaSymbols:
132 getAssembler().setSubsectionsViaSymbols(true);
135 llvm_unreachable("invalid assembler flag!");
139 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Func) {
140 // FIXME: Flag the function ISA as thumb with DW_AT_APPLE_isa.
143 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
144 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
146 // FIXME: Lift context changes into super class.
147 getAssembler().getOrCreateSymbolData(*Symbol);
148 Symbol->setVariableValue(AddValueSymbols(Value));
151 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
152 MCSymbolAttr Attribute) {
153 // Indirect symbols are handled differently, to match how 'as' handles
154 // them. This makes writing matching .o files easier.
155 if (Attribute == MCSA_IndirectSymbol) {
156 // Note that we intentionally cannot use the symbol data here; this is
157 // important for matching the string table that 'as' generates.
158 IndirectSymbolData ISD;
160 ISD.SectionData = getCurrentSectionData();
161 getAssembler().getIndirectSymbols().push_back(ISD);
165 // Adding a symbol attribute always introduces the symbol, note that an
166 // important side effect of calling getOrCreateSymbolData here is to register
167 // the symbol with the assembler.
168 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
170 // The implementation of symbol attributes is designed to match 'as', but it
171 // leaves much to desired. It doesn't really make sense to arbitrarily add and
172 // remove flags, but 'as' allows this (in particular, see .desc).
174 // In the future it might be worth trying to make these operations more well
178 case MCSA_ELF_TypeFunction:
179 case MCSA_ELF_TypeIndFunction:
180 case MCSA_ELF_TypeObject:
181 case MCSA_ELF_TypeTLS:
182 case MCSA_ELF_TypeCommon:
183 case MCSA_ELF_TypeNoType:
184 case MCSA_ELF_TypeGnuUniqueObject:
185 case MCSA_IndirectSymbol:
191 assert(0 && "Invalid symbol attribute for Mach-O!");
195 SD.setExternal(true);
196 // This effectively clears the undefined lazy bit, in Darwin 'as', although
197 // it isn't very consistent because it implements this as part of symbol
200 // FIXME: Cleanup this code, these bits should be emitted based on semantic
201 // properties, not on the order of definition, etc.
202 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
205 case MCSA_LazyReference:
206 // FIXME: This requires -dynamic.
207 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
208 if (Symbol->isUndefined())
209 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
212 // Since .reference sets the no dead strip bit, it is equivalent to
213 // .no_dead_strip in practice.
215 case MCSA_NoDeadStrip:
216 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
219 case MCSA_SymbolResolver:
220 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
223 case MCSA_PrivateExtern:
224 SD.setExternal(true);
225 SD.setPrivateExtern(true);
228 case MCSA_WeakReference:
229 // FIXME: This requires -dynamic.
230 if (Symbol->isUndefined())
231 SD.setFlags(SD.getFlags() | SF_WeakReference);
234 case MCSA_WeakDefinition:
235 // FIXME: 'as' enforces that this is defined and global. The manual claims
236 // it has to be in a coalesced section, but this isn't enforced.
237 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
240 case MCSA_WeakDefAutoPrivate:
241 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
246 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
247 // Encode the 'desc' value into the lowest implementation defined bits.
248 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
249 "Invalid .desc value!");
250 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
251 DescValue & SF_DescFlagsMask);
254 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
255 unsigned ByteAlignment) {
256 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
257 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
259 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
260 SD.setExternal(true);
261 SD.setCommon(Size, ByteAlignment);
264 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
265 unsigned Size, unsigned ByteAlignment) {
266 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
268 // The symbol may not be present, which only creates the section.
272 // FIXME: Assert that this section has the zerofill type.
274 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
276 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
278 // Emit an align fragment if necessary.
279 if (ByteAlignment != 1)
280 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
282 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
285 Symbol->setSection(*Section);
287 // Update the maximum alignment on the zero fill section if necessary.
288 if (ByteAlignment > SectData.getAlignment())
289 SectData.setAlignment(ByteAlignment);
292 // This should always be called with the thread local bss section. Like the
293 // .zerofill directive this doesn't actually switch sections on us.
294 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
295 uint64_t Size, unsigned ByteAlignment) {
296 EmitZerofill(Section, Symbol, Size, ByteAlignment);
300 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
301 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
303 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
306 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
307 int64_t Value, unsigned ValueSize,
308 unsigned MaxBytesToEmit) {
309 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
311 if (MaxBytesToEmit == 0)
312 MaxBytesToEmit = ByteAlignment;
313 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
314 getCurrentSectionData());
316 // Update the maximum alignment on the current section if necessary.
317 if (ByteAlignment > getCurrentSectionData()->getAlignment())
318 getCurrentSectionData()->setAlignment(ByteAlignment);
321 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
322 unsigned MaxBytesToEmit) {
323 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
325 if (MaxBytesToEmit == 0)
326 MaxBytesToEmit = ByteAlignment;
327 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
328 getCurrentSectionData());
329 F->setEmitNops(true);
331 // Update the maximum alignment on the current section if necessary.
332 if (ByteAlignment > getCurrentSectionData()->getAlignment())
333 getCurrentSectionData()->setAlignment(ByteAlignment);
336 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
337 MCDataFragment *DF = getOrCreateDataFragment();
339 SmallVector<MCFixup, 4> Fixups;
340 SmallString<256> Code;
341 raw_svector_ostream VecOS(Code);
342 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
345 // Add the fixups and data.
346 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
347 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
348 DF->addFixup(Fixups[i]);
350 DF->getContents().append(Code.begin(), Code.end());
353 void MCMachOStreamer::Finish() {
354 // Dump out the dwarf file & directory tables and line tables.
355 if (getContext().hasDwarfFiles()) {
356 const MCSection *DwarfLineSection = getContext().getMachOSection("__DWARF",
358 MCSectionMachO::S_ATTR_DEBUG,
359 0, SectionKind::getDataRelLocal());
360 MCDwarfFileTable::Emit(this, DwarfLineSection);
363 // We have to set the fragment atom associations so we can relax properly for
366 // First, scan the symbol table to build a lookup table from fragments to
368 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
369 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
370 ie = getAssembler().symbol_end(); it != ie; ++it) {
371 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
373 // An atom defining symbol should never be internal to a fragment.
374 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
375 DefiningSymbolMap[it->getFragment()] = it;
379 // Set the fragment atom associations by tracking the last seen atom defining
381 for (MCAssembler::iterator it = getAssembler().begin(),
382 ie = getAssembler().end(); it != ie; ++it) {
383 MCSymbolData *CurrentAtom = 0;
384 for (MCSectionData::iterator it2 = it->begin(),
385 ie2 = it->end(); it2 != ie2; ++it2) {
386 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
388 it2->setAtom(CurrentAtom);
392 this->MCObjectStreamer::Finish();
395 MCStreamer *llvm::createMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
396 raw_ostream &OS, MCCodeEmitter *CE,
398 MCMachOStreamer *S = new MCMachOStreamer(Context, TAB, OS, CE);
400 S->getAssembler().setRelaxAll(true);