1//===-- LTOModule.cpp - LLVM Link Time Optimizer --------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements the Link Time Optimization library. This library is
11// intended to be used by linker to optimize code at link time.
12//
13//===----------------------------------------------------------------------===//
14
15#include "LTOModule.h"
16#include "llvm/Constants.h"
17#include "llvm/LLVMContext.h"
18#include "llvm/Module.h"
19#include "llvm/Bitcode/ReaderWriter.h"
20#include "llvm/MC/MCExpr.h"
21#include "llvm/MC/MCInst.h"
22#include "llvm/MC/MCStreamer.h"
23#include "llvm/MC/MCSubtargetInfo.h"
24#include "llvm/MC/MCSymbol.h"
25#include "llvm/MC/MCTargetAsmParser.h"
26#include "llvm/MC/SubtargetFeature.h"
27#include "llvm/MC/MCParser/MCAsmParser.h"
28#include "llvm/Target/TargetRegisterInfo.h"
29#include "llvm/Support/Host.h"
30#include "llvm/Support/MemoryBuffer.h"
31#include "llvm/Support/Path.h"
32#include "llvm/Support/SourceMgr.h"
33#include "llvm/Support/TargetRegistry.h"
34#include "llvm/Support/TargetSelect.h"
35#include "llvm/Support/system_error.h"
36#include "llvm/ADT/OwningPtr.h"
37#include "llvm/ADT/Triple.h"
38using namespace llvm;
39
40LTOModule::LTOModule(llvm::Module *m, llvm::TargetMachine *t)
41  : _module(m), _target(t),
42    _context(*_target->getMCAsmInfo(), *_target->getRegisterInfo(), NULL),
43    _mangler(_context, *_target->getTargetData()) {}
44
45/// isBitcodeFile - Returns 'true' if the file (or memory contents) is LLVM
46/// bitcode.
47bool LTOModule::isBitcodeFile(const void *mem, size_t length) {
48  return llvm::sys::IdentifyFileType((char*)mem, length)
49    == llvm::sys::Bitcode_FileType;
50}
51
52bool LTOModule::isBitcodeFile(const char *path) {
53  return llvm::sys::Path(path).isBitcodeFile();
54}
55
56/// isBitcodeFileForTarget - Returns 'true' if the file (or memory contents) is
57/// LLVM bitcode for the specified triple.
58bool LTOModule::isBitcodeFileForTarget(const void *mem, size_t length,
59                                       const char *triplePrefix) {
60  MemoryBuffer *buffer = makeBuffer(mem, length);
61  if (!buffer)
62    return false;
63  return isTargetMatch(buffer, triplePrefix);
64}
65
66bool LTOModule::isBitcodeFileForTarget(const char *path,
67                                       const char *triplePrefix) {
68  OwningPtr<MemoryBuffer> buffer;
69  if (MemoryBuffer::getFile(path, buffer))
70    return false;
71  return isTargetMatch(buffer.take(), triplePrefix);
72}
73
74/// isTargetMatch - Returns 'true' if the memory buffer is for the specified
75/// target triple.
76bool LTOModule::isTargetMatch(MemoryBuffer *buffer, const char *triplePrefix) {
77  std::string Triple = getBitcodeTargetTriple(buffer, getGlobalContext());
78  delete buffer;
79  return strncmp(Triple.c_str(), triplePrefix, strlen(triplePrefix)) == 0;
80}
81
82/// makeLTOModule - Create an LTOModule. N.B. These methods take ownership of
83/// the buffer.
84LTOModule *LTOModule::makeLTOModule(const char *path, std::string &errMsg) {
85  OwningPtr<MemoryBuffer> buffer;
86  if (error_code ec = MemoryBuffer::getFile(path, buffer)) {
87    errMsg = ec.message();
88    return NULL;
89  }
90  return makeLTOModule(buffer.take(), errMsg);
91}
92
93LTOModule *LTOModule::makeLTOModule(int fd, const char *path,
94                                    size_t size, std::string &errMsg) {
95  return makeLTOModule(fd, path, size, size, 0, errMsg);
96}
97
98LTOModule *LTOModule::makeLTOModule(int fd, const char *path,
99                                    size_t file_size,
100                                    size_t map_size,
101                                    off_t offset,
102                                    std::string &errMsg) {
103  OwningPtr<MemoryBuffer> buffer;
104  if (error_code ec = MemoryBuffer::getOpenFile(fd, path, buffer, file_size,
105                                                map_size, offset, false)) {
106    errMsg = ec.message();
107    return NULL;
108  }
109  return makeLTOModule(buffer.take(), errMsg);
110}
111
112LTOModule *LTOModule::makeLTOModule(const void *mem, size_t length,
113                                    std::string &errMsg) {
114  OwningPtr<MemoryBuffer> buffer(makeBuffer(mem, length));
115  if (!buffer)
116    return NULL;
117  return makeLTOModule(buffer.take(), errMsg);
118}
119
120LTOModule *LTOModule::makeLTOModule(MemoryBuffer *buffer,
121                                    std::string &errMsg) {
122  static bool Initialized = false;
123  if (!Initialized) {
124    InitializeAllTargets();
125    InitializeAllTargetMCs();
126    InitializeAllAsmParsers();
127    Initialized = true;
128  }
129
130  // parse bitcode buffer
131  OwningPtr<Module> m(getLazyBitcodeModule(buffer, getGlobalContext(),
132                                           &errMsg));
133  if (!m) {
134    delete buffer;
135    return NULL;
136  }
137
138  std::string Triple = m->getTargetTriple();
139  if (Triple.empty())
140    Triple = sys::getDefaultTargetTriple();
141
142  // find machine architecture for this module
143  const Target *march = TargetRegistry::lookupTarget(Triple, errMsg);
144  if (!march)
145    return NULL;
146
147  // construct LTOModule, hand over ownership of module and target
148  SubtargetFeatures Features;
149  Features.getDefaultSubtargetFeatures(llvm::Triple(Triple));
150  std::string FeatureStr = Features.getString();
151  std::string CPU;
152  TargetOptions Options;
153  TargetMachine *target = march->createTargetMachine(Triple, CPU, FeatureStr,
154                                                     Options);
155  LTOModule *Ret = new LTOModule(m.take(), target);
156  if (Ret->parseSymbols(errMsg)) {
157    delete Ret;
158    return NULL;
159  }
160
161  return Ret;
162}
163
164/// makeBuffer - Create a MemoryBuffer from a memory range.
165MemoryBuffer *LTOModule::makeBuffer(const void *mem, size_t length) {
166  const char *startPtr = (char*)mem;
167  return MemoryBuffer::getMemBuffer(StringRef(startPtr, length), "", false);
168}
169
170/// objcClassNameFromExpression - Get string that the data pointer points to.
171bool LTOModule::objcClassNameFromExpression(Constant *c, std::string &name) {
172  if (ConstantExpr *ce = dyn_cast<ConstantExpr>(c)) {
173    Constant *op = ce->getOperand(0);
174    if (GlobalVariable *gvn = dyn_cast<GlobalVariable>(op)) {
175      Constant *cn = gvn->getInitializer();
176      if (ConstantDataArray *ca = dyn_cast<ConstantDataArray>(cn)) {
177        if (ca->isCString()) {
178          name = ".objc_class_name_" + ca->getAsCString().str();
179          return true;
180        }
181      }
182    }
183  }
184  return false;
185}
186
187/// addObjCClass - Parse i386/ppc ObjC class data structure.
188void LTOModule::addObjCClass(GlobalVariable *clgv) {
189  ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer());
190  if (!c) return;
191
192  // second slot in __OBJC,__class is pointer to superclass name
193  std::string superclassName;
194  if (objcClassNameFromExpression(c->getOperand(1), superclassName)) {
195    NameAndAttributes info;
196    StringMap<NameAndAttributes>::value_type &entry =
197      _undefines.GetOrCreateValue(superclassName);
198    if (!entry.getValue().name) {
199      const char *symbolName = entry.getKey().data();
200      info.name = symbolName;
201      info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
202      info.isFunction = false;
203      info.symbol = clgv;
204      entry.setValue(info);
205    }
206  }
207
208  // third slot in __OBJC,__class is pointer to class name
209  std::string className;
210  if (objcClassNameFromExpression(c->getOperand(2), className)) {
211    StringSet::value_type &entry = _defines.GetOrCreateValue(className);
212    entry.setValue(1);
213
214    NameAndAttributes info;
215    info.name = entry.getKey().data();
216    info.attributes = LTO_SYMBOL_PERMISSIONS_DATA |
217      LTO_SYMBOL_DEFINITION_REGULAR | LTO_SYMBOL_SCOPE_DEFAULT;
218    info.isFunction = false;
219    info.symbol = clgv;
220    _symbols.push_back(info);
221  }
222}
223
224/// addObjCCategory - Parse i386/ppc ObjC category data structure.
225void LTOModule::addObjCCategory(GlobalVariable *clgv) {
226  ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer());
227  if (!c) return;
228
229  // second slot in __OBJC,__category is pointer to target class name
230  std::string targetclassName;
231  if (!objcClassNameFromExpression(c->getOperand(1), targetclassName))
232    return;
233
234  NameAndAttributes info;
235  StringMap<NameAndAttributes>::value_type &entry =
236    _undefines.GetOrCreateValue(targetclassName);
237
238  if (entry.getValue().name)
239    return;
240
241  const char *symbolName = entry.getKey().data();
242  info.name = symbolName;
243  info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
244  info.isFunction = false;
245  info.symbol = clgv;
246  entry.setValue(info);
247}
248
249/// addObjCClassRef - Parse i386/ppc ObjC class list data structure.
250void LTOModule::addObjCClassRef(GlobalVariable *clgv) {
251  std::string targetclassName;
252  if (!objcClassNameFromExpression(clgv->getInitializer(), targetclassName))
253    return;
254
255  NameAndAttributes info;
256  StringMap<NameAndAttributes>::value_type &entry =
257    _undefines.GetOrCreateValue(targetclassName);
258  if (entry.getValue().name)
259    return;
260
261  const char *symbolName = entry.getKey().data();
262  info.name = symbolName;
263  info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
264  info.isFunction = false;
265  info.symbol = clgv;
266  entry.setValue(info);
267}
268
269/// addDefinedDataSymbol - Add a data symbol as defined to the list.
270void LTOModule::addDefinedDataSymbol(GlobalValue *v) {
271  // Add to list of defined symbols.
272  addDefinedSymbol(v, false);
273
274  // Special case i386/ppc ObjC data structures in magic sections:
275  // The issue is that the old ObjC object format did some strange
276  // contortions to avoid real linker symbols.  For instance, the
277  // ObjC class data structure is allocated statically in the executable
278  // that defines that class.  That data structures contains a pointer to
279  // its superclass.  But instead of just initializing that part of the
280  // struct to the address of its superclass, and letting the static and
281  // dynamic linkers do the rest, the runtime works by having that field
282  // instead point to a C-string that is the name of the superclass.
283  // At runtime the objc initialization updates that pointer and sets
284  // it to point to the actual super class.  As far as the linker
285  // knows it is just a pointer to a string.  But then someone wanted the
286  // linker to issue errors at build time if the superclass was not found.
287  // So they figured out a way in mach-o object format to use an absolute
288  // symbols (.objc_class_name_Foo = 0) and a floating reference
289  // (.reference .objc_class_name_Bar) to cause the linker into erroring when
290  // a class was missing.
291  // The following synthesizes the implicit .objc_* symbols for the linker
292  // from the ObjC data structures generated by the front end.
293  if (v->hasSection() /* && isTargetDarwin */) {
294    // special case if this data blob is an ObjC class definition
295    if (v->getSection().compare(0, 15, "__OBJC,__class,") == 0) {
296      if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
297        addObjCClass(gv);
298      }
299    }
300
301    // special case if this data blob is an ObjC category definition
302    else if (v->getSection().compare(0, 18, "__OBJC,__category,") == 0) {
303      if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
304        addObjCCategory(gv);
305      }
306    }
307
308    // special case if this data blob is the list of referenced classes
309    else if (v->getSection().compare(0, 18, "__OBJC,__cls_refs,") == 0) {
310      if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
311        addObjCClassRef(gv);
312      }
313    }
314  }
315}
316
317/// addDefinedFunctionSymbol - Add a function symbol as defined to the list.
318void LTOModule::addDefinedFunctionSymbol(Function *f) {
319  // add to list of defined symbols
320  addDefinedSymbol(f, true);
321}
322
323/// addDefinedSymbol - Add a defined symbol to the list.
324void LTOModule::addDefinedSymbol(GlobalValue *def, bool isFunction) {
325  // ignore all llvm.* symbols
326  if (def->getName().startswith("llvm."))
327    return;
328
329  // string is owned by _defines
330  SmallString<64> Buffer;
331  _mangler.getNameWithPrefix(Buffer, def, false);
332
333  // set alignment part log2() can have rounding errors
334  uint32_t align = def->getAlignment();
335  uint32_t attr = align ? CountTrailingZeros_32(def->getAlignment()) : 0;
336
337  // set permissions part
338  if (isFunction) {
339    attr |= LTO_SYMBOL_PERMISSIONS_CODE;
340  } else {
341    GlobalVariable *gv = dyn_cast<GlobalVariable>(def);
342    if (gv && gv->isConstant())
343      attr |= LTO_SYMBOL_PERMISSIONS_RODATA;
344    else
345      attr |= LTO_SYMBOL_PERMISSIONS_DATA;
346  }
347
348  // set definition part
349  if (def->hasWeakLinkage() || def->hasLinkOnceLinkage() ||
350      def->hasLinkerPrivateWeakLinkage() ||
351      def->hasLinkerPrivateWeakDefAutoLinkage())
352    attr |= LTO_SYMBOL_DEFINITION_WEAK;
353  else if (def->hasCommonLinkage())
354    attr |= LTO_SYMBOL_DEFINITION_TENTATIVE;
355  else
356    attr |= LTO_SYMBOL_DEFINITION_REGULAR;
357
358  // set scope part
359  if (def->hasHiddenVisibility())
360    attr |= LTO_SYMBOL_SCOPE_HIDDEN;
361  else if (def->hasProtectedVisibility())
362    attr |= LTO_SYMBOL_SCOPE_PROTECTED;
363  else if (def->hasExternalLinkage() || def->hasWeakLinkage() ||
364           def->hasLinkOnceLinkage() || def->hasCommonLinkage() ||
365           def->hasLinkerPrivateWeakLinkage())
366    attr |= LTO_SYMBOL_SCOPE_DEFAULT;
367  else if (def->hasLinkerPrivateWeakDefAutoLinkage())
368    attr |= LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
369  else
370    attr |= LTO_SYMBOL_SCOPE_INTERNAL;
371
372  StringSet::value_type &entry = _defines.GetOrCreateValue(Buffer);
373  entry.setValue(1);
374
375  // fill information structure
376  NameAndAttributes info;
377  StringRef Name = entry.getKey();
378  info.name = Name.data();
379  assert(info.name[Name.size()] == '\0');
380  info.attributes = attr;
381  info.isFunction = isFunction;
382  info.symbol = def;
383
384  // add to table of symbols
385  _symbols.push_back(info);
386}
387
388/// addAsmGlobalSymbol - Add a global symbol from module-level ASM to the
389/// defined list.
390void LTOModule::addAsmGlobalSymbol(const char *name,
391                                   lto_symbol_attributes scope) {
392  StringSet::value_type &entry = _defines.GetOrCreateValue(name);
393
394  // only add new define if not already defined
395  if (entry.getValue())
396    return;
397
398  entry.setValue(1);
399
400  NameAndAttributes &info = _undefines[entry.getKey().data()];
401
402  if (info.symbol == 0) {
403    // FIXME: This is trying to take care of module ASM like this:
404    //
405    //   module asm ".zerofill __FOO, __foo, _bar_baz_qux, 0"
406    //
407    // but is gross and its mother dresses it funny. Have the ASM parser give us
408    // more details for this type of situation so that we're not guessing so
409    // much.
410
411    // fill information structure
412    info.name = name;
413    info.attributes =
414      LTO_SYMBOL_PERMISSIONS_DATA | LTO_SYMBOL_DEFINITION_REGULAR | scope;
415    info.isFunction = false;
416    info.symbol = 0;
417
418    // add to table of symbols
419    _symbols.push_back(info);
420    return;
421  }
422
423  if (info.isFunction)
424    addDefinedFunctionSymbol(cast<Function>(info.symbol));
425  else
426    addDefinedDataSymbol(info.symbol);
427
428  _symbols.back().attributes &= ~LTO_SYMBOL_SCOPE_MASK;
429  _symbols.back().attributes |= scope;
430}
431
432/// addAsmGlobalSymbolUndef - Add a global symbol from module-level ASM to the
433/// undefined list.
434void LTOModule::addAsmGlobalSymbolUndef(const char *name) {
435  StringMap<NameAndAttributes>::value_type &entry =
436    _undefines.GetOrCreateValue(name);
437
438  _asm_undefines.push_back(entry.getKey().data());
439
440  // we already have the symbol
441  if (entry.getValue().name)
442    return;
443
444  uint32_t attr = LTO_SYMBOL_DEFINITION_UNDEFINED;;
445  attr |= LTO_SYMBOL_SCOPE_DEFAULT;
446  NameAndAttributes info;
447  info.name = entry.getKey().data();
448  info.attributes = attr;
449  info.isFunction = false;
450  info.symbol = 0;
451
452  entry.setValue(info);
453}
454
455/// addPotentialUndefinedSymbol - Add a symbol which isn't defined just yet to a
456/// list to be resolved later.
457void LTOModule::addPotentialUndefinedSymbol(GlobalValue *decl, bool isFunc) {
458  // ignore all llvm.* symbols
459  if (decl->getName().startswith("llvm."))
460    return;
461
462  // ignore all aliases
463  if (isa<GlobalAlias>(decl))
464    return;
465
466  SmallString<64> name;
467  _mangler.getNameWithPrefix(name, decl, false);
468
469  StringMap<NameAndAttributes>::value_type &entry =
470    _undefines.GetOrCreateValue(name);
471
472  // we already have the symbol
473  if (entry.getValue().name)
474    return;
475
476  NameAndAttributes info;
477
478  info.name = entry.getKey().data();
479
480  if (decl->hasExternalWeakLinkage())
481    info.attributes = LTO_SYMBOL_DEFINITION_WEAKUNDEF;
482  else
483    info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
484
485  info.isFunction = isFunc;
486  info.symbol = decl;
487
488  entry.setValue(info);
489}
490
491namespace {
492  class RecordStreamer : public MCStreamer {
493  public:
494    enum State { NeverSeen, Global, Defined, DefinedGlobal, Used };
495
496  private:
497    StringMap<State> Symbols;
498
499    void markDefined(const MCSymbol &Symbol) {
500      State &S = Symbols[Symbol.getName()];
501      switch (S) {
502      case DefinedGlobal:
503      case Global:
504        S = DefinedGlobal;
505        break;
506      case NeverSeen:
507      case Defined:
508      case Used:
509        S = Defined;
510        break;
511      }
512    }
513    void markGlobal(const MCSymbol &Symbol) {
514      State &S = Symbols[Symbol.getName()];
515      switch (S) {
516      case DefinedGlobal:
517      case Defined:
518        S = DefinedGlobal;
519        break;
520
521      case NeverSeen:
522      case Global:
523      case Used:
524        S = Global;
525        break;
526      }
527    }
528    void markUsed(const MCSymbol &Symbol) {
529      State &S = Symbols[Symbol.getName()];
530      switch (S) {
531      case DefinedGlobal:
532      case Defined:
533      case Global:
534        break;
535
536      case NeverSeen:
537      case Used:
538        S = Used;
539        break;
540      }
541    }
542
543    // FIXME: mostly copied for the obj streamer.
544    void AddValueSymbols(const MCExpr *Value) {
545      switch (Value->getKind()) {
546      case MCExpr::Target:
547        // FIXME: What should we do in here?
548        break;
549
550      case MCExpr::Constant:
551        break;
552
553      case MCExpr::Binary: {
554        const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
555        AddValueSymbols(BE->getLHS());
556        AddValueSymbols(BE->getRHS());
557        break;
558      }
559
560      case MCExpr::SymbolRef:
561        markUsed(cast<MCSymbolRefExpr>(Value)->getSymbol());
562        break;
563
564      case MCExpr::Unary:
565        AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
566        break;
567      }
568    }
569
570  public:
571    typedef StringMap<State>::const_iterator const_iterator;
572
573    const_iterator begin() {
574      return Symbols.begin();
575    }
576
577    const_iterator end() {
578      return Symbols.end();
579    }
580
581    RecordStreamer(MCContext &Context) : MCStreamer(Context) {}
582
583    virtual void EmitInstruction(const MCInst &Inst) {
584      // Scan for values.
585      for (unsigned i = Inst.getNumOperands(); i--; )
586        if (Inst.getOperand(i).isExpr())
587          AddValueSymbols(Inst.getOperand(i).getExpr());
588    }
589    virtual void EmitLabel(MCSymbol *Symbol) {
590      Symbol->setSection(*getCurrentSection());
591      markDefined(*Symbol);
592    }
593    virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
594      // FIXME: should we handle aliases?
595      markDefined(*Symbol);
596    }
597    virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) {
598      if (Attribute == MCSA_Global)
599        markGlobal(*Symbol);
600    }
601    virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
602                              unsigned Size , unsigned ByteAlignment) {
603      markDefined(*Symbol);
604    }
605    virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
606                                  unsigned ByteAlignment) {
607      markDefined(*Symbol);
608    }
609
610    // Noop calls.
611    virtual void ChangeSection(const MCSection *Section) {}
612    virtual void InitSections() {}
613    virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) {}
614    virtual void EmitThumbFunc(MCSymbol *Func) {}
615    virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {}
616    virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {}
617    virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {}
618    virtual void EmitCOFFSymbolStorageClass(int StorageClass) {}
619    virtual void EmitCOFFSymbolType(int Type) {}
620    virtual void EndCOFFSymbolDef() {}
621    virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
622    virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
623                                       unsigned ByteAlignment) {}
624    virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
625                                uint64_t Size, unsigned ByteAlignment) {}
626    virtual void EmitBytes(StringRef Data, unsigned AddrSpace) {}
627    virtual void EmitValueImpl(const MCExpr *Value, unsigned Size,
628                               unsigned AddrSpace) {}
629    virtual void EmitULEB128Value(const MCExpr *Value) {}
630    virtual void EmitSLEB128Value(const MCExpr *Value) {}
631    virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
632                                      unsigned ValueSize,
633                                      unsigned MaxBytesToEmit) {}
634    virtual void EmitCodeAlignment(unsigned ByteAlignment,
635                                   unsigned MaxBytesToEmit) {}
636    virtual bool EmitValueToOffset(const MCExpr *Offset,
637                                   unsigned char Value ) { return false; }
638    virtual void EmitFileDirective(StringRef Filename) {}
639    virtual void EmitDwarfAdvanceLineAddr(int64_t LineDelta,
640                                          const MCSymbol *LastLabel,
641                                          const MCSymbol *Label,
642                                          unsigned PointerSize) {}
643    virtual void FinishImpl() {}
644  };
645} // end anonymous namespace
646
647/// addAsmGlobalSymbols - Add global symbols from module-level ASM to the
648/// defined or undefined lists.
649bool LTOModule::addAsmGlobalSymbols(std::string &errMsg) {
650  const std::string &inlineAsm = _module->getModuleInlineAsm();
651  if (inlineAsm.empty())
652    return false;
653
654  OwningPtr<RecordStreamer> Streamer(new RecordStreamer(_context));
655  MemoryBuffer *Buffer = MemoryBuffer::getMemBuffer(inlineAsm);
656  SourceMgr SrcMgr;
657  SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
658  OwningPtr<MCAsmParser> Parser(createMCAsmParser(SrcMgr,
659                                                  _context, *Streamer,
660                                                  *_target->getMCAsmInfo()));
661  OwningPtr<MCSubtargetInfo> STI(_target->getTarget().
662                      createMCSubtargetInfo(_target->getTargetTriple(),
663                                            _target->getTargetCPU(),
664                                            _target->getTargetFeatureString()));
665  OwningPtr<MCTargetAsmParser>
666    TAP(_target->getTarget().createMCAsmParser(*STI, *Parser.get()));
667  if (!TAP) {
668    errMsg = "target " + std::string(_target->getTarget().getName()) +
669        " does not define AsmParser.";
670    return true;
671  }
672
673  Parser->setTargetParser(*TAP);
674  int Res = Parser->Run(false);
675  if (Res)
676    return true;
677
678  for (RecordStreamer::const_iterator i = Streamer->begin(),
679         e = Streamer->end(); i != e; ++i) {
680    StringRef Key = i->first();
681    RecordStreamer::State Value = i->second;
682    if (Value == RecordStreamer::DefinedGlobal)
683      addAsmGlobalSymbol(Key.data(), LTO_SYMBOL_SCOPE_DEFAULT);
684    else if (Value == RecordStreamer::Defined)
685      addAsmGlobalSymbol(Key.data(), LTO_SYMBOL_SCOPE_INTERNAL);
686    else if (Value == RecordStreamer::Global ||
687             Value == RecordStreamer::Used)
688      addAsmGlobalSymbolUndef(Key.data());
689  }
690  return false;
691}
692
693/// isDeclaration - Return 'true' if the global value is a declaration.
694static bool isDeclaration(const GlobalValue &V) {
695  if (V.hasAvailableExternallyLinkage())
696    return true;
697  if (V.isMaterializable())
698    return false;
699  return V.isDeclaration();
700}
701
702/// parseSymbols - Parse the symbols from the module and model-level ASM and add
703/// them to either the defined or undefined lists.
704bool LTOModule::parseSymbols(std::string &errMsg) {
705  // add functions
706  for (Module::iterator f = _module->begin(), e = _module->end(); f != e; ++f) {
707    if (isDeclaration(*f))
708      addPotentialUndefinedSymbol(f, true);
709    else
710      addDefinedFunctionSymbol(f);
711  }
712
713  // add data
714  for (Module::global_iterator v = _module->global_begin(),
715         e = _module->global_end(); v !=  e; ++v) {
716    if (isDeclaration(*v))
717      addPotentialUndefinedSymbol(v, false);
718    else
719      addDefinedDataSymbol(v);
720  }
721
722  // add asm globals
723  if (addAsmGlobalSymbols(errMsg))
724    return true;
725
726  // add aliases
727  for (Module::alias_iterator a = _module->alias_begin(),
728         e = _module->alias_end(); a != e; ++a) {
729    if (isDeclaration(*a->getAliasedGlobal()))
730      // Is an alias to a declaration.
731      addPotentialUndefinedSymbol(a, false);
732    else
733      addDefinedDataSymbol(a);
734  }
735
736  // make symbols for all undefines
737  for (StringMap<NameAndAttributes>::iterator u =_undefines.begin(),
738         e = _undefines.end(); u != e; ++u) {
739    // If this symbol also has a definition, then don't make an undefine because
740    // it is a tentative definition.
741    if (_defines.count(u->getKey())) continue;
742    NameAndAttributes info = u->getValue();
743    _symbols.push_back(info);
744  }
745
746  return false;
747}
748