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/MC/TargetAsmBackend.h"
24 #include "llvm/Support/Dwarf.h"
25 #include "llvm/Support/ErrorHandling.h"
26 #include "llvm/Support/raw_ostream.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) {}
41 /// @name MCStreamer Interface
44 virtual void InitSections();
45 virtual void EmitLabel(MCSymbol *Symbol);
46 virtual void EmitEHSymAttributes(const MCSymbol *Symbol,
48 virtual void EmitAssemblerFlag(MCAssemblerFlag Flag);
49 virtual void EmitThumbFunc(MCSymbol *Func);
50 virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value);
51 virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute);
52 virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue);
53 virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
54 unsigned ByteAlignment);
55 virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {
56 assert(0 && "macho doesn't support this directive");
58 virtual void EmitCOFFSymbolStorageClass(int StorageClass) {
59 assert(0 && "macho doesn't support this directive");
61 virtual void EmitCOFFSymbolType(int Type) {
62 assert(0 && "macho doesn't support this directive");
64 virtual void EndCOFFSymbolDef() {
65 assert(0 && "macho doesn't support this directive");
67 virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {
68 assert(0 && "macho doesn't support this directive");
70 virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size) {
71 assert(0 && "macho doesn't support this directive");
73 virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol = 0,
74 unsigned Size = 0, unsigned ByteAlignment = 0);
75 virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
76 uint64_t Size, unsigned ByteAlignment = 0);
77 virtual void EmitBytes(StringRef Data, unsigned AddrSpace);
78 virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
79 unsigned ValueSize = 1,
80 unsigned MaxBytesToEmit = 0);
81 virtual void EmitCodeAlignment(unsigned ByteAlignment,
82 unsigned MaxBytesToEmit = 0);
84 virtual void EmitFileDirective(StringRef Filename) {
85 // FIXME: Just ignore the .file; it isn't important enough to fail the
88 //report_fatal_error("unsupported directive: '.file'");
91 virtual void Finish();
96 } // end anonymous namespace.
98 void MCMachOStreamer::InitSections() {
99 SwitchSection(getContext().getMachOSection("__TEXT", "__text",
100 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
101 0, SectionKind::getText()));
105 void MCMachOStreamer::EmitEHSymAttributes(const MCSymbol *Symbol,
106 MCSymbol *EHSymbol) {
108 getAssembler().getOrCreateSymbolData(*Symbol);
110 EmitSymbolAttribute(EHSymbol, MCSA_Global);
111 if (SD.getFlags() & SF_WeakDefinition)
112 EmitSymbolAttribute(EHSymbol, MCSA_WeakDefinition);
113 if (SD.isPrivateExtern())
114 EmitSymbolAttribute(EHSymbol, MCSA_PrivateExtern);
117 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
118 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
120 // isSymbolLinkerVisible uses the section.
121 Symbol->setSection(*getCurrentSection());
122 // We have to create a new fragment if this is an atom defining symbol,
123 // fragments cannot span atoms.
124 if (getAssembler().isSymbolLinkerVisible(*Symbol))
125 new MCDataFragment(getCurrentSectionData());
127 MCObjectStreamer::EmitLabel(Symbol);
129 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
130 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
131 // to clear the weak reference and weak definition bits too, but the
132 // implementation was buggy. For now we just try to match 'as', for
135 // FIXME: Cleanup this code, these bits should be emitted based on semantic
136 // properties, not on the order of definition, etc.
137 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
140 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
141 // Let the target do whatever target specific stuff it needs to do.
142 getAssembler().getBackend().HandleAssemblerFlag(Flag);
143 // Do any generic stuff we need to do.
145 case MCAF_SyntaxUnified: return; // no-op here.
146 case MCAF_Code16: return; // no-op here.
147 case MCAF_Code32: return; // no-op here.
148 case MCAF_SubsectionsViaSymbols:
149 getAssembler().setSubsectionsViaSymbols(true);
152 llvm_unreachable("invalid assembler flag!");
156 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Symbol) {
157 // FIXME: Flag the function ISA as thumb with DW_AT_APPLE_isa.
159 // Remember that the function is a thumb function. Fixup and relocation
160 // values will need adjusted.
161 getAssembler().setIsThumbFunc(Symbol);
163 // Mark the thumb bit on the symbol.
164 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
165 SD.setFlags(SD.getFlags() | SF_ThumbFunc);
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:
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_SymbolResolver:
244 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
247 case MCSA_PrivateExtern:
248 SD.setExternal(true);
249 SD.setPrivateExtern(true);
252 case MCSA_WeakReference:
253 // FIXME: This requires -dynamic.
254 if (Symbol->isUndefined())
255 SD.setFlags(SD.getFlags() | SF_WeakReference);
258 case MCSA_WeakDefinition:
259 // FIXME: 'as' enforces that this is defined and global. The manual claims
260 // it has to be in a coalesced section, but this isn't enforced.
261 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
264 case MCSA_WeakDefAutoPrivate:
265 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
270 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
271 // Encode the 'desc' value into the lowest implementation defined bits.
272 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
273 "Invalid .desc value!");
274 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
275 DescValue & SF_DescFlagsMask);
278 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
279 unsigned ByteAlignment) {
280 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
281 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
283 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
284 SD.setExternal(true);
285 SD.setCommon(Size, ByteAlignment);
288 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
289 unsigned Size, unsigned ByteAlignment) {
290 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
292 // The symbol may not be present, which only creates the section.
296 // FIXME: Assert that this section has the zerofill type.
298 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
300 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
302 // Emit an align fragment if necessary.
303 if (ByteAlignment != 1)
304 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
306 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
309 Symbol->setSection(*Section);
311 // Update the maximum alignment on the zero fill section if necessary.
312 if (ByteAlignment > SectData.getAlignment())
313 SectData.setAlignment(ByteAlignment);
316 // This should always be called with the thread local bss section. Like the
317 // .zerofill directive this doesn't actually switch sections on us.
318 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
319 uint64_t Size, unsigned ByteAlignment) {
320 EmitZerofill(Section, Symbol, Size, ByteAlignment);
324 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
325 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
327 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
330 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
331 int64_t Value, unsigned ValueSize,
332 unsigned MaxBytesToEmit) {
333 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
335 if (MaxBytesToEmit == 0)
336 MaxBytesToEmit = ByteAlignment;
337 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
338 getCurrentSectionData());
340 // Update the maximum alignment on the current section if necessary.
341 if (ByteAlignment > getCurrentSectionData()->getAlignment())
342 getCurrentSectionData()->setAlignment(ByteAlignment);
345 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
346 unsigned MaxBytesToEmit) {
347 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
349 if (MaxBytesToEmit == 0)
350 MaxBytesToEmit = ByteAlignment;
351 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
352 getCurrentSectionData());
353 F->setEmitNops(true);
355 // Update the maximum alignment on the current section if necessary.
356 if (ByteAlignment > getCurrentSectionData()->getAlignment())
357 getCurrentSectionData()->setAlignment(ByteAlignment);
360 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
361 MCDataFragment *DF = getOrCreateDataFragment();
363 SmallVector<MCFixup, 4> Fixups;
364 SmallString<256> Code;
365 raw_svector_ostream VecOS(Code);
366 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
369 // Add the fixups and data.
370 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
371 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
372 DF->addFixup(Fixups[i]);
374 DF->getContents().append(Code.begin(), Code.end());
377 void MCMachOStreamer::Finish() {
380 // We have to set the fragment atom associations so we can relax properly for
383 // First, scan the symbol table to build a lookup table from fragments to
385 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
386 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
387 ie = getAssembler().symbol_end(); it != ie; ++it) {
388 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
390 // An atom defining symbol should never be internal to a fragment.
391 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
392 DefiningSymbolMap[it->getFragment()] = it;
396 // Set the fragment atom associations by tracking the last seen atom defining
398 for (MCAssembler::iterator it = getAssembler().begin(),
399 ie = getAssembler().end(); it != ie; ++it) {
400 MCSymbolData *CurrentAtom = 0;
401 for (MCSectionData::iterator it2 = it->begin(),
402 ie2 = it->end(); it2 != ie2; ++it2) {
403 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
405 it2->setAtom(CurrentAtom);
409 this->MCObjectStreamer::Finish();
412 MCStreamer *llvm::createMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
413 raw_ostream &OS, MCCodeEmitter *CE,
415 MCMachOStreamer *S = new MCMachOStreamer(Context, TAB, OS, CE);
417 S->getAssembler().setRelaxAll(true);