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 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 EmitValueToAlignment(unsigned ByteAlignment, int64_t Value = 0,
78 unsigned ValueSize = 1,
79 unsigned MaxBytesToEmit = 0);
80 virtual void EmitCodeAlignment(unsigned ByteAlignment,
81 unsigned MaxBytesToEmit = 0);
83 virtual void EmitFileDirective(StringRef Filename) {
84 // FIXME: Just ignore the .file; it isn't important enough to fail the
87 //report_fatal_error("unsupported directive: '.file'");
90 virtual void Finish();
95 } // end anonymous namespace.
97 void MCMachOStreamer::InitSections() {
98 SwitchSection(getContext().getMachOSection("__TEXT", "__text",
99 MCSectionMachO::S_ATTR_PURE_INSTRUCTIONS,
100 0, SectionKind::getText()));
104 void MCMachOStreamer::EmitLabel(MCSymbol *Symbol) {
105 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
107 // isSymbolLinkerVisible uses the section.
108 Symbol->setSection(*CurSection);
109 // We have to create a new fragment if this is an atom defining symbol,
110 // fragments cannot span atoms.
111 if (getAssembler().isSymbolLinkerVisible(*Symbol))
112 new MCDataFragment(getCurrentSectionData());
114 MCObjectStreamer::EmitLabel(Symbol);
116 MCSymbolData &SD = getAssembler().getSymbolData(*Symbol);
117 // This causes the reference type flag to be cleared. Darwin 'as' was "trying"
118 // to clear the weak reference and weak definition bits too, but the
119 // implementation was buggy. For now we just try to match 'as', for
122 // FIXME: Cleanup this code, these bits should be emitted based on semantic
123 // properties, not on the order of definition, etc.
124 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeMask);
127 void MCMachOStreamer::EmitAssemblerFlag(MCAssemblerFlag Flag) {
128 // Let the target do whatever target specific stuff it needs to do.
129 getAssembler().getBackend().HandleAssemblerFlag(Flag);
130 // Do any generic stuff we need to do.
132 case MCAF_SyntaxUnified: return; // no-op here.
133 case MCAF_Code16: return; // no-op here.
134 case MCAF_Code32: return; // no-op here.
135 case MCAF_SubsectionsViaSymbols:
136 getAssembler().setSubsectionsViaSymbols(true);
139 llvm_unreachable("invalid assembler flag!");
143 void MCMachOStreamer::EmitThumbFunc(MCSymbol *Func) {
144 // FIXME: Flag the function ISA as thumb with DW_AT_APPLE_isa.
147 void MCMachOStreamer::EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
148 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
150 // FIXME: Lift context changes into super class.
151 getAssembler().getOrCreateSymbolData(*Symbol);
152 Symbol->setVariableValue(AddValueSymbols(Value));
155 void MCMachOStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
156 MCSymbolAttr Attribute) {
157 // Indirect symbols are handled differently, to match how 'as' handles
158 // them. This makes writing matching .o files easier.
159 if (Attribute == MCSA_IndirectSymbol) {
160 // Note that we intentionally cannot use the symbol data here; this is
161 // important for matching the string table that 'as' generates.
162 IndirectSymbolData ISD;
164 ISD.SectionData = getCurrentSectionData();
165 getAssembler().getIndirectSymbols().push_back(ISD);
169 // Adding a symbol attribute always introduces the symbol, note that an
170 // important side effect of calling getOrCreateSymbolData here is to register
171 // the symbol with the assembler.
172 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
174 // The implementation of symbol attributes is designed to match 'as', but it
175 // leaves much to desired. It doesn't really make sense to arbitrarily add and
176 // remove flags, but 'as' allows this (in particular, see .desc).
178 // In the future it might be worth trying to make these operations more well
182 case MCSA_ELF_TypeFunction:
183 case MCSA_ELF_TypeIndFunction:
184 case MCSA_ELF_TypeObject:
185 case MCSA_ELF_TypeTLS:
186 case MCSA_ELF_TypeCommon:
187 case MCSA_ELF_TypeNoType:
188 case MCSA_ELF_TypeGnuUniqueObject:
189 case MCSA_IndirectSymbol:
195 assert(0 && "Invalid symbol attribute for Mach-O!");
199 SD.setExternal(true);
200 // This effectively clears the undefined lazy bit, in Darwin 'as', although
201 // it isn't very consistent because it implements this as part of symbol
204 // FIXME: Cleanup this code, these bits should be emitted based on semantic
205 // properties, not on the order of definition, etc.
206 SD.setFlags(SD.getFlags() & ~SF_ReferenceTypeUndefinedLazy);
209 case MCSA_LazyReference:
210 // FIXME: This requires -dynamic.
211 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
212 if (Symbol->isUndefined())
213 SD.setFlags(SD.getFlags() | SF_ReferenceTypeUndefinedLazy);
216 // Since .reference sets the no dead strip bit, it is equivalent to
217 // .no_dead_strip in practice.
219 case MCSA_NoDeadStrip:
220 SD.setFlags(SD.getFlags() | SF_NoDeadStrip);
223 case MCSA_SymbolResolver:
224 SD.setFlags(SD.getFlags() | SF_SymbolResolver);
227 case MCSA_PrivateExtern:
228 SD.setExternal(true);
229 SD.setPrivateExtern(true);
232 case MCSA_WeakReference:
233 // FIXME: This requires -dynamic.
234 if (Symbol->isUndefined())
235 SD.setFlags(SD.getFlags() | SF_WeakReference);
238 case MCSA_WeakDefinition:
239 // FIXME: 'as' enforces that this is defined and global. The manual claims
240 // it has to be in a coalesced section, but this isn't enforced.
241 SD.setFlags(SD.getFlags() | SF_WeakDefinition);
244 case MCSA_WeakDefAutoPrivate:
245 SD.setFlags(SD.getFlags() | SF_WeakDefinition | SF_WeakReference);
250 void MCMachOStreamer::EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {
251 // Encode the 'desc' value into the lowest implementation defined bits.
252 assert(DescValue == (DescValue & SF_DescFlagsMask) &&
253 "Invalid .desc value!");
254 getAssembler().getOrCreateSymbolData(*Symbol).setFlags(
255 DescValue & SF_DescFlagsMask);
258 void MCMachOStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
259 unsigned ByteAlignment) {
260 // FIXME: Darwin 'as' does appear to allow redef of a .comm by itself.
261 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
263 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
264 SD.setExternal(true);
265 SD.setCommon(Size, ByteAlignment);
268 void MCMachOStreamer::EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
269 unsigned Size, unsigned ByteAlignment) {
270 MCSectionData &SectData = getAssembler().getOrCreateSectionData(*Section);
272 // The symbol may not be present, which only creates the section.
276 // FIXME: Assert that this section has the zerofill type.
278 assert(Symbol->isUndefined() && "Cannot define a symbol twice!");
280 MCSymbolData &SD = getAssembler().getOrCreateSymbolData(*Symbol);
282 // Emit an align fragment if necessary.
283 if (ByteAlignment != 1)
284 new MCAlignFragment(ByteAlignment, 0, 0, ByteAlignment, &SectData);
286 MCFragment *F = new MCFillFragment(0, 0, Size, &SectData);
289 Symbol->setSection(*Section);
291 // Update the maximum alignment on the zero fill section if necessary.
292 if (ByteAlignment > SectData.getAlignment())
293 SectData.setAlignment(ByteAlignment);
296 // This should always be called with the thread local bss section. Like the
297 // .zerofill directive this doesn't actually switch sections on us.
298 void MCMachOStreamer::EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
299 uint64_t Size, unsigned ByteAlignment) {
300 EmitZerofill(Section, Symbol, Size, ByteAlignment);
304 void MCMachOStreamer::EmitBytes(StringRef Data, unsigned AddrSpace) {
305 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
307 getOrCreateDataFragment()->getContents().append(Data.begin(), Data.end());
310 void MCMachOStreamer::EmitValueToAlignment(unsigned ByteAlignment,
311 int64_t Value, unsigned ValueSize,
312 unsigned MaxBytesToEmit) {
313 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
315 if (MaxBytesToEmit == 0)
316 MaxBytesToEmit = ByteAlignment;
317 new MCAlignFragment(ByteAlignment, Value, ValueSize, MaxBytesToEmit,
318 getCurrentSectionData());
320 // Update the maximum alignment on the current section if necessary.
321 if (ByteAlignment > getCurrentSectionData()->getAlignment())
322 getCurrentSectionData()->setAlignment(ByteAlignment);
325 void MCMachOStreamer::EmitCodeAlignment(unsigned ByteAlignment,
326 unsigned MaxBytesToEmit) {
327 // TODO: This is exactly the same as WinCOFFStreamer. Consider merging into
329 if (MaxBytesToEmit == 0)
330 MaxBytesToEmit = ByteAlignment;
331 MCAlignFragment *F = new MCAlignFragment(ByteAlignment, 0, 1, MaxBytesToEmit,
332 getCurrentSectionData());
333 F->setEmitNops(true);
335 // Update the maximum alignment on the current section if necessary.
336 if (ByteAlignment > getCurrentSectionData()->getAlignment())
337 getCurrentSectionData()->setAlignment(ByteAlignment);
340 void MCMachOStreamer::EmitInstToData(const MCInst &Inst) {
341 MCDataFragment *DF = getOrCreateDataFragment();
343 SmallVector<MCFixup, 4> Fixups;
344 SmallString<256> Code;
345 raw_svector_ostream VecOS(Code);
346 getAssembler().getEmitter().EncodeInstruction(Inst, VecOS, Fixups);
349 // Add the fixups and data.
350 for (unsigned i = 0, e = Fixups.size(); i != e; ++i) {
351 Fixups[i].setOffset(Fixups[i].getOffset() + DF->getContents().size());
352 DF->addFixup(Fixups[i]);
354 DF->getContents().append(Code.begin(), Code.end());
357 void MCMachOStreamer::Finish() {
358 // We have to set the fragment atom associations so we can relax properly for
361 // First, scan the symbol table to build a lookup table from fragments to
363 DenseMap<const MCFragment*, MCSymbolData*> DefiningSymbolMap;
364 for (MCAssembler::symbol_iterator it = getAssembler().symbol_begin(),
365 ie = getAssembler().symbol_end(); it != ie; ++it) {
366 if (getAssembler().isSymbolLinkerVisible(it->getSymbol()) &&
368 // An atom defining symbol should never be internal to a fragment.
369 assert(it->getOffset() == 0 && "Invalid offset in atom defining symbol!");
370 DefiningSymbolMap[it->getFragment()] = it;
374 // Set the fragment atom associations by tracking the last seen atom defining
376 for (MCAssembler::iterator it = getAssembler().begin(),
377 ie = getAssembler().end(); it != ie; ++it) {
378 MCSymbolData *CurrentAtom = 0;
379 for (MCSectionData::iterator it2 = it->begin(),
380 ie2 = it->end(); it2 != ie2; ++it2) {
381 if (MCSymbolData *SD = DefiningSymbolMap.lookup(it2))
383 it2->setAtom(CurrentAtom);
387 this->MCObjectStreamer::Finish();
390 MCStreamer *llvm::createMachOStreamer(MCContext &Context, TargetAsmBackend &TAB,
391 raw_ostream &OS, MCCodeEmitter *CE,
393 MCMachOStreamer *S = new MCMachOStreamer(Context, TAB, OS, CE);
395 S->getAssembler().setRelaxAll(true);