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_IndirectSymbol:
215 assert(0 && "Invalid symbol attribute for Mach-O!");
219 SD.setExternal(true);
220 // This effectively clears the undefined lazy bit, in Darwin 'as', although
221 // it isn't very consistent because it implements this as part of symbol
224 // FIXME: Cleanup this code, these bits should be emitted based on semantic
225 // properties, not on the order of definition, etc.
226 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
229 case MCSA_LazyReference:
230 // FIXME: This requires -dynamic.
231 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
232 if (Symbol->isUndefined())
233 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
236 // Since .reference sets the no dead strip bit, it is equivalent to
237 // .no_dead_strip in practice.
239 case MCSA_NoDeadStrip:
240 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
243 case MCSA_PrivateExtern:
244 SD.setExternal(true);
245 SD.setPrivateExtern(true);
248 case MCSA_WeakReference:
249 // FIXME: This requires -dynamic.
250 if (Symbol->isUndefined())
251 SD.setFlags(SD.getFlags() | SF_WeakReference);
254 case MCSA_WeakDefinition:
255 // FIXME: 'as' enforces that this is defined and global. The manual claims
256 // it has to be in a coalesced section, but this isn't enforced.
257 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
260 case MCSA_WeakDefAutoPrivate:
261 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
266 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
267 // Encode the 'desc' value into the lowest implementation defined bits.
268 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
269 "Invalid .desc value!");
270 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
271 DescValue & SF_DescFlagsMask);
274 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
275 unsigned ByteAlignment) {
276 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
277 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
279 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
280 SD.setExternal(true);
281 SD.setCommon(Size, ByteAlignment);
284 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
285 unsigned Size, unsigned ByteAlignment) {
286 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
288 // The symbol may not be present, which only creates the section.
292 // FIXME: Assert that this section has the zerofill type.
294 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
296 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
298 // Emit an align fragment if necessary.
299 if (ByteAlignment != 1)
300 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
302 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
305 Symbol->setSection(*Section);
307 // Update the maximum alignment on the zero fill section if necessary.
308 if (ByteAlignment > SectData.getAlignment())
309 SectData.setAlignment(ByteAlignment);
312 // This should always be called with the thread local bss section. Like the
313 // .zerofill directive this doesn't actually switch sections on us.
314 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
315 uint64_t Size, unsigned ByteAlignment) {
316 EmitZerofill(Section, Symbol, Size, ByteAlignment);
320 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
321 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
323 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
326 void MCMachOStreamer::EmitValue(const MCExpr *Value, unsigned Size,
327 unsigned AddrSpace) {
328 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
330 MCDataFragment *DF = getOrCreateDataFragment();
332 // Avoid fixups when possible.
334 if (AddValueSymbols(Value)->EvaluateAsAbsolute(AbsValue)) {
335 // FIXME: Endianness assumption.
336 for (unsigned i = 0; i != Size; ++i)
337 DF->getContents().push_back(uint8_t(AbsValue >> (i * 8)));
339 DF->addFixup(MCFixup::Create(DF->getContents().size(),
340 AddValueSymbols(Value),
341 MCFixup::getKindForSize(Size)));
342 DF->getContents().resize(DF->getContents().size() + Size, 0);
346 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
347 int64_t Value, unsigned ValueSize,
348 unsigned MaxBytesToEmit) {
349 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
351 if (MaxBytesToEmit == 0)
352 MaxBytesToEmit = ByteAlignment;
353 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
354 getCurrentSectionData());
356 // Update the maximum alignment on the current section if necessary.
357 if (ByteAlignment > getCurrentSectionData()->getAlignment())
358 getCurrentSectionData()->setAlignment(ByteAlignment);
361 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
362 unsigned MaxBytesToEmit) {
363 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
365 if (MaxBytesToEmit == 0)
366 MaxBytesToEmit = ByteAlignment;
367 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
368 getCurrentSectionData());
369 F->setEmitNops(true);
371 // Update the maximum alignment on the current section if necessary.
372 if (ByteAlignment > getCurrentSectionData()->getAlignment())
373 getCurrentSectionData()->setAlignment(ByteAlignment);
376 void MCMachOStreamer::EmitValueToOffset(const MCExpr *Offset,
377 unsigned char Value) {
378 new MCOrgFragment(*Offset, Value, getCurrentSectionData());
381 void MCMachOStreamer::EmitInstToFragment(const MCInst &Inst) {
382 MCInstFragment *IF = new MCInstFragment(Inst, getCurrentSectionData());
384 // Add the fixups and data.
386 // FIXME: Revisit this design decision when relaxation is done, we may be
387 // able to get away with not storing any extra data in the MCInst.
388 SmallVector<MCFixup, 4> Fixups;
389 SmallString<256> Code;
390 raw_svector_ostream VecOS(Code);
391 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
394 IF->getCode() = Code;
395 IF->getFixups() = Fixups;
398 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
399 MCDataFragment *DF = getOrCreateDataFragment();
401 SmallVector<MCFixup, 4> Fixups;
402 SmallString<256> Code;
403 raw_svector_ostream VecOS(Code);
404 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
407 // Add the fixups and data.
408 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
409 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
410 DF->addFixup(Fixups[i]);
412 DF->getContents().append(Code.begin(), Code.end());
415 void MCMachOStreamer::Finish() {
416 // Dump out the dwarf file & directory tables and line tables.
417 if (getContext().hasDwarfFiles()) {
418 const MCSection *DwarfLineSection = getContext().getMachOSection("__DWARF",
420 MCSectionMachO::S_ATTR_DEBUG,
421 0, SectionKind::getDataRelLocal());
422 MCDwarfFileTable::Emit(this, DwarfLineSection);
425 // We have to set the fragment atom associations so we can relax properly for
428 // First, scan the symbol table to build a lookup table from fragments to
430 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
431 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
432 ie = getAssembler().symbol_end(); it != ie; ++it) {
433 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
435 // An atom defining symbol should never be internal to a fragment.
436 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
437 DefiningSymbolMap[it->getFragment()] = it;
441 // Set the fragment atom associations by tracking the last seen atom defining
443 for (MCAssembler::iterator it = getAssembler().begin(),
444 ie = getAssembler().end(); it != ie; ++it) {
445 MCSymbolData *CurrentAtom = 0;
446 for (MCSectionData::iterator it2 = it->begin(),
447 ie2 = it->end(); it2 != ie2; ++it2) {
448 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
450 it2->setAtom(CurrentAtom);
454 this->MCObjectStreamer::Finish();
457 MCStreamer *llvm::createMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
458 raw_ostream &OS, MCCodeEmitter *CE,
460 MCMachOStreamer *S = new MCMachOStreamer(Context, TAB, OS, CE);
462 S->getAssembler().setRelaxAll(true);