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"
27 #include "llvm/Target/TargetAsmInfo.h"
33 class MCMachOStreamer : public MCObjectStreamer {
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) {}
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 EmitCOFFSecRel32(MCSymbol const *Symbol) {
67 assert(0 && "macho doesn't support this directive");
69 virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
70 assert(0 && "macho doesn't support this directive");
72 virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
73 assert(0 && "macho doesn't support this directive");
75 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
76 unsigned Size = 0, unsigned ByteAlignment = 0);
77 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
78 uint64_t Size, unsigned ByteAlignment = 0);
79 virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
80 virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
81 unsigned ValueSize = 1,
82 unsigned MaxBytesToEmit = 0);
83 virtual void EmitCodeAlignment(unsigned ByteAlignment,
84 unsigned MaxBytesToEmit = 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 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
110 // isSymbolLinkerVisible uses the section.
111 Symbol->setSection(*getCurrentSection());
112 // We have to create a new fragment if this is an atom defining symbol,
113 // fragments cannot span atoms.
114 if (getAssembler().isSymbolLinkerVisible(*Symbol))
115 new MCDataFragment(getCurrentSectionData());
117 MCObjectStreamer::EmitLabel(Symbol);
119 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
120 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
121 // to clear the weak reference and weak definition bits too, but the
122 // implementation was buggy. For now we just try to match 'as', for
125 // FIXME: Cleanup this code, these bits should be emitted based on semantic
126 // properties, not on the order of definition, etc.
127 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
130 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
131 // Let the target do whatever target specific stuff it needs to do.
132 getAssembler().getBackend().HandleAssemblerFlag(Flag);
133 // Do any generic stuff we need to do.
135 case MCAF_SyntaxUnified: return; // no-op here.
136 case MCAF_Code16: return; // no-op here.
137 case MCAF_Code32: return; // no-op here.
138 case MCAF_SubsectionsViaSymbols:
139 getAssembler().setSubsectionsViaSymbols(true);
142 llvm_unreachable("invalid assembler flag!");
146 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
147 // FIXME: Flag the function ISA as thumb with DW_AT_APPLE_isa.
149 // Remember that the function is a thumb function. Fixup and relocation
150 // values will need adjusted.
151 getAssembler().setIsThumbFunc(Symbol);
153 // Mark the thumb bit on the symbol.
154 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
155 SD.setFlags(SD.getFlags() | SF_ThumbFunc);
158 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
159 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
161 // FIXME: Lift context changes into super class.
162 getAssembler().getOrCreateSymbolData(*Symbol);
163 Symbol->setVariableValue(AddValueSymbols(Value));
166 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
167 MCSymbolAttr Attribute) {
168 // Indirect symbols are handled differently, to match how 'as' handles
169 // them. This makes writing matching .o files easier.
170 if (Attribute == MCSA_IndirectSymbol) {
171 // Note that we intentionally cannot use the symbol data here; this is
172 // important for matching the string table that 'as' generates.
173 IndirectSymbolData ISD;
175 ISD.SectionData = getCurrentSectionData();
176 getAssembler().getIndirectSymbols().push_back(ISD);
180 // Adding a symbol attribute always introduces the symbol, note that an
181 // important side effect of calling getOrCreateSymbolData here is to register
182 // the symbol with the assembler.
183 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
185 // The implementation of symbol attributes is designed to match 'as', but it
186 // leaves much to desired. It doesn't really make sense to arbitrarily add and
187 // remove flags, but 'as' allows this (in particular, see .desc).
189 // In the future it might be worth trying to make these operations more well
193 case MCSA_ELF_TypeFunction:
194 case MCSA_ELF_TypeIndFunction:
195 case MCSA_ELF_TypeObject:
196 case MCSA_ELF_TypeTLS:
197 case MCSA_ELF_TypeCommon:
198 case MCSA_ELF_TypeNoType:
199 case MCSA_ELF_TypeGnuUniqueObject:
200 case MCSA_IndirectSymbol:
206 assert(0 && "Invalid symbol attribute for Mach-O!");
210 SD.setExternal(true);
211 // This effectively clears the undefined lazy bit, in Darwin 'as', although
212 // it isn't very consistent because it implements this as part of symbol
215 // FIXME: Cleanup this code, these bits should be emitted based on semantic
216 // properties, not on the order of definition, etc.
217 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
220 case MCSA_LazyReference:
221 // FIXME: This requires -dynamic.
222 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
223 if (Symbol->isUndefined())
224 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
227 // Since .reference sets the no dead strip bit, it is equivalent to
228 // .no_dead_strip in practice.
230 case MCSA_NoDeadStrip:
231 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
234 case MCSA_SymbolResolver:
235 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
238 case MCSA_PrivateExtern:
239 SD.setExternal(true);
240 SD.setPrivateExtern(true);
243 case MCSA_WeakReference:
244 // FIXME: This requires -dynamic.
245 if (Symbol->isUndefined())
246 SD.setFlags(SD.getFlags() | SF_WeakReference);
249 case MCSA_WeakDefinition:
250 // FIXME: 'as' enforces that this is defined and global. The manual claims
251 // it has to be in a coalesced section, but this isn't enforced.
252 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
255 case MCSA_WeakDefAutoPrivate:
256 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
261 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
262 // Encode the 'desc' value into the lowest implementation defined bits.
263 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
264 "Invalid .desc value!");
265 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
266 DescValue & SF_DescFlagsMask);
269 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
270 unsigned ByteAlignment) {
271 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
272 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
274 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
275 SD.setExternal(true);
276 SD.setCommon(Size, ByteAlignment);
279 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
280 unsigned Size, unsigned ByteAlignment) {
281 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
283 // The symbol may not be present, which only creates the section.
287 // FIXME: Assert that this section has the zerofill type.
289 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
291 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
293 // Emit an align fragment if necessary.
294 if (ByteAlignment != 1)
295 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
297 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
300 Symbol->setSection(*Section);
302 // Update the maximum alignment on the zero fill section if necessary.
303 if (ByteAlignment > SectData.getAlignment())
304 SectData.setAlignment(ByteAlignment);
307 // This should always be called with the thread local bss section. Like the
308 // .zerofill directive this doesn't actually switch sections on us.
309 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
310 uint64_t Size, unsigned ByteAlignment) {
311 EmitZerofill(Section, Symbol, Size, ByteAlignment);
315 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
316 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
318 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
321 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
322 int64_t Value, unsigned ValueSize,
323 unsigned MaxBytesToEmit) {
324 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
326 if (MaxBytesToEmit == 0)
327 MaxBytesToEmit = ByteAlignment;
328 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
329 getCurrentSectionData());
331 // Update the maximum alignment on the current section if necessary.
332 if (ByteAlignment > getCurrentSectionData()->getAlignment())
333 getCurrentSectionData()->setAlignment(ByteAlignment);
336 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
337 unsigned MaxBytesToEmit) {
338 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
340 if (MaxBytesToEmit == 0)
341 MaxBytesToEmit = ByteAlignment;
342 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
343 getCurrentSectionData());
344 F->setEmitNops(true);
346 // Update the maximum alignment on the current section if necessary.
347 if (ByteAlignment > getCurrentSectionData()->getAlignment())
348 getCurrentSectionData()->setAlignment(ByteAlignment);
351 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
352 MCDataFragment *DF = getOrCreateDataFragment();
354 SmallVector<MCFixup, 4> Fixups;
355 SmallString<256> Code;
356 raw_svector_ostream VecOS(Code);
357 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
360 // Add the fixups and data.
361 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
362 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
363 DF->addFixup(Fixups[i]);
365 DF->getContents().append(Code.begin(), Code.end());
368 void MCMachOStreamer::Finish() {
369 // We have to set the fragment atom associations so we can relax properly for
372 // First, scan the symbol table to build a lookup table from fragments to
374 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
375 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
376 ie = getAssembler().symbol_end(); it != ie; ++it) {
377 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
379 // An atom defining symbol should never be internal to a fragment.
380 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
381 DefiningSymbolMap[it->getFragment()] = it;
385 // Set the fragment atom associations by tracking the last seen atom defining
387 for (MCAssembler::iterator it = getAssembler().begin(),
388 ie = getAssembler().end(); it != ie; ++it) {
389 MCSymbolData *CurrentAtom = 0;
390 for (MCSectionData::iterator it2 = it->begin(),
391 ie2 = it->end(); it2 != ie2; ++it2) {
392 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
394 it2->setAtom(CurrentAtom);
398 this->MCObjectStreamer::Finish();
401 MCStreamer *llvm::createMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
402 raw_ostream &OS, MCCodeEmitter *CE,
404 MCMachOStreamer *S = new MCMachOStreamer(Context, TAB, OS, CE);
406 S->getAssembler().setRelaxAll(true);