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'");
95 virtual void EmitDwarfFileDirective(unsigned FileNo, StringRef Filename) {
96 // FIXME: Just ignore the .file; it isn't important enough to fail the
99 //report_fatal_error("unsupported directive: '.file'");
102 virtual void Finish();
107 } // end anonymous namespace.
109 void MCMachOStreamer::InitSections() {
110 SwitchSection(getContext().getMachOSection("__TEXT", "__text",
111 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
112 0, SectionKind::getText()));
116 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
117 // TODO: This is almost exactly the same as WinCOFFStreamer. Consider merging
118 // into MCObjectStreamer.
119 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
120 assert(!Symbol->isVariable() && "Cannot emit a variable symbol!");
121 assert(CurSection && "Cannot emit before setting section!");
123 Symbol->setSection(*CurSection);
125 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
127 // We have to create a new fragment if this is an atom defining symbol,
128 // fragments cannot span atoms.
129 if (getAssembler().isSymbolLinkerVisible(SD.getSymbol()))
130 new MCDataFragment(getCurrentSectionData());
132 // FIXME: This is wasteful, we don't necessarily need to create a data
133 // fragment. Instead, we should mark the symbol as pointing into the data
134 // fragment if it exists, otherwise we should just queue the label and set its
135 // fragment pointer when we emit the next fragment.
136 MCDataFragment *F = getOrCreateDataFragment();
137 assert(!SD.getFragment() && "Unexpected fragment on symbol data!");
139 SD.setOffset(F->getContents().size());
141 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
142 // to clear the weak reference and weak definition bits too, but the
143 // implementation was buggy. For now we just try to match 'as', for
146 // FIXME: Cleanup this code, these bits should be emitted based on semantic
147 // properties, not on the order of definition, etc.
148 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
151 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
153 case MCAF_SyntaxUnified: return; // no-op here.
154 case MCAF_Code16: return; // no-op here.
155 case MCAF_Code32: return; // no-op here.
156 case MCAF_SubsectionsViaSymbols:
157 getAssembler().setSubsectionsViaSymbols(true);
160 llvm_unreachable("invalid assembler flag!");
164 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Func) {
165 // FIXME: Flag the function ISA as thumb with DW_AT_APPLE_isa.
168 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
169 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
171 // FIXME: Lift context changes into super class.
172 getAssembler().getOrCreateSymbolData(*Symbol);
173 Symbol->setVariableValue(AddValueSymbols(Value));
176 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
177 MCSymbolAttr Attribute) {
178 // Indirect symbols are handled differently, to match how 'as' handles
179 // them. This makes writing matching .o files easier.
180 if (Attribute == MCSA_IndirectSymbol) {
181 // Note that we intentionally cannot use the symbol data here; this is
182 // important for matching the string table that 'as' generates.
183 IndirectSymbolData ISD;
185 ISD.SectionData = getCurrentSectionData();
186 getAssembler().getIndirectSymbols().push_back(ISD);
190 // Adding a symbol attribute always introduces the symbol, note that an
191 // important side effect of calling getOrCreateSymbolData here is to register
192 // the symbol with the assembler.
193 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
195 // The implementation of symbol attributes is designed to match 'as', but it
196 // leaves much to desired. It doesn't really make sense to arbitrarily add and
197 // remove flags, but 'as' allows this (in particular, see .desc).
199 // In the future it might be worth trying to make these operations more well
203 case MCSA_ELF_TypeFunction:
204 case MCSA_ELF_TypeIndFunction:
205 case MCSA_ELF_TypeObject:
206 case MCSA_ELF_TypeTLS:
207 case MCSA_ELF_TypeCommon:
208 case MCSA_ELF_TypeNoType:
209 case MCSA_ELF_TypeGnuUniqueObject:
210 case MCSA_IndirectSymbol:
216 assert(0 && "Invalid symbol attribute for Mach-O!");
220 SD.setExternal(true);
221 // This effectively clears the undefined lazy bit, in Darwin 'as', although
222 // it isn't very consistent because it implements this as part of symbol
225 // FIXME: Cleanup this code, these bits should be emitted based on semantic
226 // properties, not on the order of definition, etc.
227 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
230 case MCSA_LazyReference:
231 // FIXME: This requires -dynamic.
232 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
233 if (Symbol->isUndefined())
234 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
237 // Since .reference sets the no dead strip bit, it is equivalent to
238 // .no_dead_strip in practice.
240 case MCSA_NoDeadStrip:
241 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
244 case MCSA_PrivateExtern:
245 SD.setExternal(true);
246 SD.setPrivateExtern(true);
249 case MCSA_WeakReference:
250 // FIXME: This requires -dynamic.
251 if (Symbol->isUndefined())
252 SD.setFlags(SD.getFlags() | SF_WeakReference);
255 case MCSA_WeakDefinition:
256 // FIXME: 'as' enforces that this is defined and global. The manual claims
257 // it has to be in a coalesced section, but this isn't enforced.
258 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
261 case MCSA_WeakDefAutoPrivate:
262 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
267 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
268 // Encode the 'desc' value into the lowest implementation defined bits.
269 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
270 "Invalid .desc value!");
271 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
272 DescValue & SF_DescFlagsMask);
275 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
276 unsigned ByteAlignment) {
277 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
278 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
280 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
281 SD.setExternal(true);
282 SD.setCommon(Size, ByteAlignment);
285 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
286 unsigned Size, unsigned ByteAlignment) {
287 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
289 // The symbol may not be present, which only creates the section.
293 // FIXME: Assert that this section has the zerofill type.
295 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
297 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
299 // Emit an align fragment if necessary.
300 if (ByteAlignment != 1)
301 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
303 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
306 Symbol->setSection(*Section);
308 // Update the maximum alignment on the zero fill section if necessary.
309 if (ByteAlignment > SectData.getAlignment())
310 SectData.setAlignment(ByteAlignment);
313 // This should always be called with the thread local bss section. Like the
314 // .zerofill directive this doesn't actually switch sections on us.
315 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
316 uint64_t Size, unsigned ByteAlignment) {
317 EmitZerofill(Section, Symbol, Size, ByteAlignment);
321 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
322 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
324 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
327 void MCMachOStreamer::EmitValue(const MCExpr *Value, unsigned Size,
328 unsigned AddrSpace) {
329 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
331 MCDataFragment *DF = getOrCreateDataFragment();
333 // Avoid fixups when possible.
335 if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) {
336 // FIXME: Endianness assumption.
337 for (unsigned i = 0; i != Size; ++i)
338 DF->getContents().push_back(uint8_t(AbsValue >> (i * 8)));
340 DF->addFixup(MCFixup::Create(DF->getContents().size(),
341 AddValueSymbols(Value),
342 MCFixup::getKindForSize(Size)));
343 DF->getContents().resize(DF->getContents().size() + Size, 0);
347 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
348 int64_t Value, unsigned ValueSize,
349 unsigned MaxBytesToEmit) {
350 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
352 if (MaxBytesToEmit == 0)
353 MaxBytesToEmit = ByteAlignment;
354 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
355 getCurrentSectionData());
357 // Update the maximum alignment on the current section if necessary.
358 if (ByteAlignment > getCurrentSectionData()->getAlignment())
359 getCurrentSectionData()->setAlignment(ByteAlignment);
362 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
363 unsigned MaxBytesToEmit) {
364 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
366 if (MaxBytesToEmit == 0)
367 MaxBytesToEmit = ByteAlignment;
368 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
369 getCurrentSectionData());
370 F->setEmitNops(true);
372 // Update the maximum alignment on the current section if necessary.
373 if (ByteAlignment > getCurrentSectionData()->getAlignment())
374 getCurrentSectionData()->setAlignment(ByteAlignment);
377 void MCMachOStreamer::EmitValueToOffset(const MCExpr *Offset,
378 unsigned char Value) {
379 new MCOrgFragment(*Offset, Value, getCurrentSectionData());
382 void MCMachOStreamer::EmitInstToFragment(const MCInst &Inst) {
383 MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
385 // Add the fixups and data.
387 // FIXME: Revisit this design decision when relaxation is done, we may be
388 // able to get away with not storing any extra data in the MCInst.
389 SmallVector<MCFixup, 4> Fixups;
390 SmallString<256> Code;
391 raw_svector_ostream VecOS(Code);
392 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
395 IF->getCode() = Code;
396 IF->getFixups() = Fixups;
399 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
400 MCDataFragment *DF = getOrCreateDataFragment();
402 SmallVector<MCFixup, 4> Fixups;
403 SmallString<256> Code;
404 raw_svector_ostream VecOS(Code);
405 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
408 // Add the fixups and data.
409 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
410 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
411 DF->addFixup(Fixups[i]);
413 DF->getContents().append(Code.begin(), Code.end());
416 void MCMachOStreamer::Finish() {
417 // Dump out the dwarf file & directory tables and line tables.
418 if (getContext().hasDwarfFiles()) {
419 const MCSection *DwarfLineSection = getContext().getMachOSection("__DWARF",
421 MCSectionMachO::S_ATTR_DEBUG,
422 0, SectionKind::getDataRelLocal());
423 MCDwarfFileTable::Emit(this, DwarfLineSection);
426 // We have to set the fragment atom associations so we can relax properly for
429 // First, scan the symbol table to build a lookup table from fragments to
431 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
432 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
433 ie = getAssembler().symbol_end(); it != ie; ++it) {
434 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
436 // An atom defining symbol should never be internal to a fragment.
437 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
438 DefiningSymbolMap[it->getFragment()] = it;
442 // Set the fragment atom associations by tracking the last seen atom defining
444 for (MCAssembler::iterator it = getAssembler().begin(),
445 ie = getAssembler().end(); it != ie; ++it) {
446 MCSymbolData *CurrentAtom = 0;
447 for (MCSectionData::iterator it2 = it->begin(),
448 ie2 = it->end(); it2 != ie2; ++it2) {
449 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
451 it2->setAtom(CurrentAtom);
455 this->MCObjectStreamer::Finish();
458 MCStreamer *llvm::createMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
459 raw_ostream &OS, MCCodeEmitter *CE,
461 MCMachOStreamer *S = new MCMachOStreamer(Context, TAB, OS, CE);
463 S->getAssembler().setRelaxAll(true);