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 "llvm/LTO/LTOModule.h"
16#include "llvm/ADT/OwningPtr.h"
17#include "llvm/ADT/Triple.h"
18#include "llvm/Bitcode/ReaderWriter.h"
19#include "llvm/IR/Constants.h"
20#include "llvm/IR/LLVMContext.h"
21#include "llvm/IR/Module.h"
22#include "llvm/MC/MCExpr.h"
23#include "llvm/MC/MCInst.h"
24#include "llvm/MC/MCInstrInfo.h"
25#include "llvm/MC/MCParser/MCAsmParser.h"
26#include "llvm/MC/MCStreamer.h"
27#include "llvm/MC/MCSubtargetInfo.h"
28#include "llvm/MC/MCSymbol.h"
29#include "llvm/MC/MCTargetAsmParser.h"
30#include "llvm/MC/SubtargetFeature.h"
31#include "llvm/Support/CommandLine.h"
32#include "llvm/Support/Host.h"
33#include "llvm/Support/FileSystem.h"
34#include "llvm/Support/MemoryBuffer.h"
35#include "llvm/Support/Path.h"
36#include "llvm/Support/SourceMgr.h"
37#include "llvm/Support/TargetRegistry.h"
38#include "llvm/Support/TargetSelect.h"
39#include "llvm/Support/system_error.h"
40#include "llvm/Target/TargetRegisterInfo.h"
41#include "llvm/Transforms/Utils/GlobalStatus.h"
42using namespace llvm;
43
44LTOModule::LTOModule(llvm::Module *m, llvm::TargetMachine *t)
45  : _module(m), _target(t),
46    _context(_target->getMCAsmInfo(), _target->getRegisterInfo(), NULL),
47    _mangler(t) {}
48
49/// isBitcodeFile - Returns 'true' if the file (or memory contents) is LLVM
50/// bitcode.
51bool LTOModule::isBitcodeFile(const void *mem, size_t length) {
52  return sys::fs::identify_magic(StringRef((const char *)mem, length)) ==
53         sys::fs::file_magic::bitcode;
54}
55
56bool LTOModule::isBitcodeFile(const char *path) {
57  sys::fs::file_magic type;
58  if (sys::fs::identify_magic(path, type))
59    return false;
60  return type == sys::fs::file_magic::bitcode;
61}
62
63/// isBitcodeFileForTarget - Returns 'true' if the file (or memory contents) is
64/// LLVM bitcode for the specified triple.
65bool LTOModule::isBitcodeFileForTarget(const void *mem, size_t length,
66                                       const char *triplePrefix) {
67  MemoryBuffer *buffer = makeBuffer(mem, length);
68  if (!buffer)
69    return false;
70  return isTargetMatch(buffer, triplePrefix);
71}
72
73bool LTOModule::isBitcodeFileForTarget(const char *path,
74                                       const char *triplePrefix) {
75  OwningPtr<MemoryBuffer> buffer;
76  if (MemoryBuffer::getFile(path, buffer))
77    return false;
78  return isTargetMatch(buffer.take(), triplePrefix);
79}
80
81/// isTargetMatch - Returns 'true' if the memory buffer is for the specified
82/// target triple.
83bool LTOModule::isTargetMatch(MemoryBuffer *buffer, const char *triplePrefix) {
84  std::string Triple = getBitcodeTargetTriple(buffer, getGlobalContext());
85  delete buffer;
86  return strncmp(Triple.c_str(), triplePrefix, strlen(triplePrefix)) == 0;
87}
88
89/// makeLTOModule - Create an LTOModule. N.B. These methods take ownership of
90/// the buffer.
91LTOModule *LTOModule::makeLTOModule(const char *path, TargetOptions options,
92                                    std::string &errMsg) {
93  OwningPtr<MemoryBuffer> buffer;
94  if (error_code ec = MemoryBuffer::getFile(path, buffer)) {
95    errMsg = ec.message();
96    return NULL;
97  }
98  return makeLTOModule(buffer.take(), options, errMsg);
99}
100
101LTOModule *LTOModule::makeLTOModule(int fd, const char *path,
102                                    size_t size, TargetOptions options,
103                                    std::string &errMsg) {
104  return makeLTOModule(fd, path, size, 0, options, errMsg);
105}
106
107LTOModule *LTOModule::makeLTOModule(int fd, const char *path,
108                                    size_t map_size,
109                                    off_t offset,
110                                    TargetOptions options,
111                                    std::string &errMsg) {
112  OwningPtr<MemoryBuffer> buffer;
113  if (error_code ec =
114          MemoryBuffer::getOpenFileSlice(fd, path, buffer, map_size, offset)) {
115    errMsg = ec.message();
116    return NULL;
117  }
118  return makeLTOModule(buffer.take(), options, errMsg);
119}
120
121LTOModule *LTOModule::makeLTOModule(const void *mem, size_t length,
122                                    TargetOptions options,
123                                    std::string &errMsg) {
124  OwningPtr<MemoryBuffer> buffer(makeBuffer(mem, length));
125  if (!buffer)
126    return NULL;
127  return makeLTOModule(buffer.take(), options, errMsg);
128}
129
130LTOModule *LTOModule::makeLTOModule(MemoryBuffer *buffer,
131                                    TargetOptions options,
132                                    std::string &errMsg) {
133  // parse bitcode buffer
134  OwningPtr<Module> m(getLazyBitcodeModule(buffer, getGlobalContext(),
135                                           &errMsg));
136  if (!m) {
137    delete buffer;
138    return NULL;
139  }
140
141  std::string TripleStr = m->getTargetTriple();
142  if (TripleStr.empty())
143    TripleStr = sys::getDefaultTargetTriple();
144  llvm::Triple Triple(TripleStr);
145
146  // find machine architecture for this module
147  const Target *march = TargetRegistry::lookupTarget(TripleStr, errMsg);
148  if (!march)
149    return NULL;
150
151  // construct LTOModule, hand over ownership of module and target
152  SubtargetFeatures Features;
153  Features.getDefaultSubtargetFeatures(Triple);
154  std::string FeatureStr = Features.getString();
155  // Set a default CPU for Darwin triples.
156  std::string CPU;
157  if (Triple.isOSDarwin()) {
158    if (Triple.getArch() == llvm::Triple::x86_64)
159      CPU = "core2";
160    else if (Triple.getArch() == llvm::Triple::x86)
161      CPU = "yonah";
162  }
163
164  TargetMachine *target = march->createTargetMachine(TripleStr, CPU, FeatureStr,
165                                                     options);
166  m->MaterializeAllPermanently();
167
168  LTOModule *Ret = new LTOModule(m.take(), target);
169  if (Ret->parseSymbols(errMsg)) {
170    delete Ret;
171    return NULL;
172  }
173
174  return Ret;
175}
176
177/// makeBuffer - Create a MemoryBuffer from a memory range.
178MemoryBuffer *LTOModule::makeBuffer(const void *mem, size_t length) {
179  const char *startPtr = (const char*)mem;
180  return MemoryBuffer::getMemBuffer(StringRef(startPtr, length), "", false);
181}
182
183/// objcClassNameFromExpression - Get string that the data pointer points to.
184bool
185LTOModule::objcClassNameFromExpression(const Constant *c, std::string &name) {
186  if (const ConstantExpr *ce = dyn_cast<ConstantExpr>(c)) {
187    Constant *op = ce->getOperand(0);
188    if (GlobalVariable *gvn = dyn_cast<GlobalVariable>(op)) {
189      Constant *cn = gvn->getInitializer();
190      if (ConstantDataArray *ca = dyn_cast<ConstantDataArray>(cn)) {
191        if (ca->isCString()) {
192          name = ".objc_class_name_" + ca->getAsCString().str();
193          return true;
194        }
195      }
196    }
197  }
198  return false;
199}
200
201/// addObjCClass - Parse i386/ppc ObjC class data structure.
202void LTOModule::addObjCClass(const GlobalVariable *clgv) {
203  const ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer());
204  if (!c) return;
205
206  // second slot in __OBJC,__class is pointer to superclass name
207  std::string superclassName;
208  if (objcClassNameFromExpression(c->getOperand(1), superclassName)) {
209    NameAndAttributes info;
210    StringMap<NameAndAttributes>::value_type &entry =
211      _undefines.GetOrCreateValue(superclassName);
212    if (!entry.getValue().name) {
213      const char *symbolName = entry.getKey().data();
214      info.name = symbolName;
215      info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
216      info.isFunction = false;
217      info.symbol = clgv;
218      entry.setValue(info);
219    }
220  }
221
222  // third slot in __OBJC,__class is pointer to class name
223  std::string className;
224  if (objcClassNameFromExpression(c->getOperand(2), className)) {
225    StringSet::value_type &entry = _defines.GetOrCreateValue(className);
226    entry.setValue(1);
227
228    NameAndAttributes info;
229    info.name = entry.getKey().data();
230    info.attributes = LTO_SYMBOL_PERMISSIONS_DATA |
231      LTO_SYMBOL_DEFINITION_REGULAR | LTO_SYMBOL_SCOPE_DEFAULT;
232    info.isFunction = false;
233    info.symbol = clgv;
234    _symbols.push_back(info);
235  }
236}
237
238/// addObjCCategory - Parse i386/ppc ObjC category data structure.
239void LTOModule::addObjCCategory(const GlobalVariable *clgv) {
240  const ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer());
241  if (!c) return;
242
243  // second slot in __OBJC,__category is pointer to target class name
244  std::string targetclassName;
245  if (!objcClassNameFromExpression(c->getOperand(1), targetclassName))
246    return;
247
248  NameAndAttributes info;
249  StringMap<NameAndAttributes>::value_type &entry =
250    _undefines.GetOrCreateValue(targetclassName);
251
252  if (entry.getValue().name)
253    return;
254
255  const char *symbolName = entry.getKey().data();
256  info.name = symbolName;
257  info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
258  info.isFunction = false;
259  info.symbol = clgv;
260  entry.setValue(info);
261}
262
263/// addObjCClassRef - Parse i386/ppc ObjC class list data structure.
264void LTOModule::addObjCClassRef(const GlobalVariable *clgv) {
265  std::string targetclassName;
266  if (!objcClassNameFromExpression(clgv->getInitializer(), targetclassName))
267    return;
268
269  NameAndAttributes info;
270  StringMap<NameAndAttributes>::value_type &entry =
271    _undefines.GetOrCreateValue(targetclassName);
272  if (entry.getValue().name)
273    return;
274
275  const char *symbolName = entry.getKey().data();
276  info.name = symbolName;
277  info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
278  info.isFunction = false;
279  info.symbol = clgv;
280  entry.setValue(info);
281}
282
283/// addDefinedDataSymbol - Add a data symbol as defined to the list.
284void LTOModule::addDefinedDataSymbol(const GlobalValue *v) {
285  // Add to list of defined symbols.
286  addDefinedSymbol(v, false);
287
288  if (!v->hasSection() /* || !isTargetDarwin */)
289    return;
290
291  // Special case i386/ppc ObjC data structures in magic sections:
292  // The issue is that the old ObjC object format did some strange
293  // contortions to avoid real linker symbols.  For instance, the
294  // ObjC class data structure is allocated statically in the executable
295  // that defines that class.  That data structures contains a pointer to
296  // its superclass.  But instead of just initializing that part of the
297  // struct to the address of its superclass, and letting the static and
298  // dynamic linkers do the rest, the runtime works by having that field
299  // instead point to a C-string that is the name of the superclass.
300  // At runtime the objc initialization updates that pointer and sets
301  // it to point to the actual super class.  As far as the linker
302  // knows it is just a pointer to a string.  But then someone wanted the
303  // linker to issue errors at build time if the superclass was not found.
304  // So they figured out a way in mach-o object format to use an absolute
305  // symbols (.objc_class_name_Foo = 0) and a floating reference
306  // (.reference .objc_class_name_Bar) to cause the linker into erroring when
307  // a class was missing.
308  // The following synthesizes the implicit .objc_* symbols for the linker
309  // from the ObjC data structures generated by the front end.
310
311  // special case if this data blob is an ObjC class definition
312  if (v->getSection().compare(0, 15, "__OBJC,__class,") == 0) {
313    if (const GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
314      addObjCClass(gv);
315    }
316  }
317
318  // special case if this data blob is an ObjC category definition
319  else if (v->getSection().compare(0, 18, "__OBJC,__category,") == 0) {
320    if (const GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
321      addObjCCategory(gv);
322    }
323  }
324
325  // special case if this data blob is the list of referenced classes
326  else if (v->getSection().compare(0, 18, "__OBJC,__cls_refs,") == 0) {
327    if (const GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
328      addObjCClassRef(gv);
329    }
330  }
331}
332
333/// addDefinedFunctionSymbol - Add a function symbol as defined to the list.
334void LTOModule::addDefinedFunctionSymbol(const Function *f) {
335  // add to list of defined symbols
336  addDefinedSymbol(f, true);
337}
338
339static bool canBeHidden(const GlobalValue *GV) {
340  GlobalValue::LinkageTypes L = GV->getLinkage();
341
342  if (L != GlobalValue::LinkOnceODRLinkage)
343    return false;
344
345  if (GV->hasUnnamedAddr())
346    return true;
347
348  GlobalStatus GS;
349  if (GlobalStatus::analyzeGlobal(GV, GS))
350    return false;
351
352  return !GS.IsCompared;
353}
354
355/// addDefinedSymbol - Add a defined symbol to the list.
356void LTOModule::addDefinedSymbol(const GlobalValue *def, bool isFunction) {
357  // ignore all llvm.* symbols
358  if (def->getName().startswith("llvm."))
359    return;
360
361  // string is owned by _defines
362  SmallString<64> Buffer;
363  _mangler.getNameWithPrefix(Buffer, def, false);
364
365  // set alignment part log2() can have rounding errors
366  uint32_t align = def->getAlignment();
367  uint32_t attr = align ? countTrailingZeros(def->getAlignment()) : 0;
368
369  // set permissions part
370  if (isFunction) {
371    attr |= LTO_SYMBOL_PERMISSIONS_CODE;
372  } else {
373    const GlobalVariable *gv = dyn_cast<GlobalVariable>(def);
374    if (gv && gv->isConstant())
375      attr |= LTO_SYMBOL_PERMISSIONS_RODATA;
376    else
377      attr |= LTO_SYMBOL_PERMISSIONS_DATA;
378  }
379
380  // set definition part
381  if (def->hasWeakLinkage() || def->hasLinkOnceLinkage() ||
382      def->hasLinkerPrivateWeakLinkage())
383    attr |= LTO_SYMBOL_DEFINITION_WEAK;
384  else if (def->hasCommonLinkage())
385    attr |= LTO_SYMBOL_DEFINITION_TENTATIVE;
386  else
387    attr |= LTO_SYMBOL_DEFINITION_REGULAR;
388
389  // set scope part
390  if (def->hasHiddenVisibility())
391    attr |= LTO_SYMBOL_SCOPE_HIDDEN;
392  else if (def->hasProtectedVisibility())
393    attr |= LTO_SYMBOL_SCOPE_PROTECTED;
394  else if (canBeHidden(def))
395    attr |= LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
396  else if (def->hasExternalLinkage() || def->hasWeakLinkage() ||
397           def->hasLinkOnceLinkage() || def->hasCommonLinkage() ||
398           def->hasLinkerPrivateWeakLinkage())
399    attr |= LTO_SYMBOL_SCOPE_DEFAULT;
400  else
401    attr |= LTO_SYMBOL_SCOPE_INTERNAL;
402
403  StringSet::value_type &entry = _defines.GetOrCreateValue(Buffer);
404  entry.setValue(1);
405
406  // fill information structure
407  NameAndAttributes info;
408  StringRef Name = entry.getKey();
409  info.name = Name.data();
410  assert(info.name[Name.size()] == '\0');
411  info.attributes = attr;
412  info.isFunction = isFunction;
413  info.symbol = def;
414
415  // add to table of symbols
416  _symbols.push_back(info);
417}
418
419/// addAsmGlobalSymbol - Add a global symbol from module-level ASM to the
420/// defined list.
421void LTOModule::addAsmGlobalSymbol(const char *name,
422                                   lto_symbol_attributes scope) {
423  StringSet::value_type &entry = _defines.GetOrCreateValue(name);
424
425  // only add new define if not already defined
426  if (entry.getValue())
427    return;
428
429  entry.setValue(1);
430
431  NameAndAttributes &info = _undefines[entry.getKey().data()];
432
433  if (info.symbol == 0) {
434    // FIXME: This is trying to take care of module ASM like this:
435    //
436    //   module asm ".zerofill __FOO, __foo, _bar_baz_qux, 0"
437    //
438    // but is gross and its mother dresses it funny. Have the ASM parser give us
439    // more details for this type of situation so that we're not guessing so
440    // much.
441
442    // fill information structure
443    info.name = entry.getKey().data();
444    info.attributes =
445      LTO_SYMBOL_PERMISSIONS_DATA | LTO_SYMBOL_DEFINITION_REGULAR | scope;
446    info.isFunction = false;
447    info.symbol = 0;
448
449    // add to table of symbols
450    _symbols.push_back(info);
451    return;
452  }
453
454  if (info.isFunction)
455    addDefinedFunctionSymbol(cast<Function>(info.symbol));
456  else
457    addDefinedDataSymbol(info.symbol);
458
459  _symbols.back().attributes &= ~LTO_SYMBOL_SCOPE_MASK;
460  _symbols.back().attributes |= scope;
461}
462
463/// addAsmGlobalSymbolUndef - Add a global symbol from module-level ASM to the
464/// undefined list.
465void LTOModule::addAsmGlobalSymbolUndef(const char *name) {
466  StringMap<NameAndAttributes>::value_type &entry =
467    _undefines.GetOrCreateValue(name);
468
469  _asm_undefines.push_back(entry.getKey().data());
470
471  // we already have the symbol
472  if (entry.getValue().name)
473    return;
474
475  uint32_t attr = LTO_SYMBOL_DEFINITION_UNDEFINED;;
476  attr |= LTO_SYMBOL_SCOPE_DEFAULT;
477  NameAndAttributes info;
478  info.name = entry.getKey().data();
479  info.attributes = attr;
480  info.isFunction = false;
481  info.symbol = 0;
482
483  entry.setValue(info);
484}
485
486/// addPotentialUndefinedSymbol - Add a symbol which isn't defined just yet to a
487/// list to be resolved later.
488void
489LTOModule::addPotentialUndefinedSymbol(const GlobalValue *decl, bool isFunc) {
490  // ignore all llvm.* symbols
491  if (decl->getName().startswith("llvm."))
492    return;
493
494  // ignore all aliases
495  if (isa<GlobalAlias>(decl))
496    return;
497
498  SmallString<64> name;
499  _mangler.getNameWithPrefix(name, decl, false);
500
501  StringMap<NameAndAttributes>::value_type &entry =
502    _undefines.GetOrCreateValue(name);
503
504  // we already have the symbol
505  if (entry.getValue().name)
506    return;
507
508  NameAndAttributes info;
509
510  info.name = entry.getKey().data();
511
512  if (decl->hasExternalWeakLinkage())
513    info.attributes = LTO_SYMBOL_DEFINITION_WEAKUNDEF;
514  else
515    info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
516
517  info.isFunction = isFunc;
518  info.symbol = decl;
519
520  entry.setValue(info);
521}
522
523namespace {
524  class RecordStreamer : public MCStreamer {
525  public:
526    enum State { NeverSeen, Global, Defined, DefinedGlobal, Used };
527
528  private:
529    StringMap<State> Symbols;
530
531    void markDefined(const MCSymbol &Symbol) {
532      State &S = Symbols[Symbol.getName()];
533      switch (S) {
534      case DefinedGlobal:
535      case Global:
536        S = DefinedGlobal;
537        break;
538      case NeverSeen:
539      case Defined:
540      case Used:
541        S = Defined;
542        break;
543      }
544    }
545    void markGlobal(const MCSymbol &Symbol) {
546      State &S = Symbols[Symbol.getName()];
547      switch (S) {
548      case DefinedGlobal:
549      case Defined:
550        S = DefinedGlobal;
551        break;
552
553      case NeverSeen:
554      case Global:
555      case Used:
556        S = Global;
557        break;
558      }
559    }
560    void markUsed(const MCSymbol &Symbol) {
561      State &S = Symbols[Symbol.getName()];
562      switch (S) {
563      case DefinedGlobal:
564      case Defined:
565      case Global:
566        break;
567
568      case NeverSeen:
569      case Used:
570        S = Used;
571        break;
572      }
573    }
574
575    // FIXME: mostly copied for the obj streamer.
576    void AddValueSymbols(const MCExpr *Value) {
577      switch (Value->getKind()) {
578      case MCExpr::Target:
579        // FIXME: What should we do in here?
580        break;
581
582      case MCExpr::Constant:
583        break;
584
585      case MCExpr::Binary: {
586        const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
587        AddValueSymbols(BE->getLHS());
588        AddValueSymbols(BE->getRHS());
589        break;
590      }
591
592      case MCExpr::SymbolRef:
593        markUsed(cast<MCSymbolRefExpr>(Value)->getSymbol());
594        break;
595
596      case MCExpr::Unary:
597        AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
598        break;
599      }
600    }
601
602  public:
603    typedef StringMap<State>::const_iterator const_iterator;
604
605    const_iterator begin() {
606      return Symbols.begin();
607    }
608
609    const_iterator end() {
610      return Symbols.end();
611    }
612
613    RecordStreamer(MCContext &Context) : MCStreamer(Context, 0) {}
614
615    virtual void EmitInstruction(const MCInst &Inst) {
616      // Scan for values.
617      for (unsigned i = Inst.getNumOperands(); i--; )
618        if (Inst.getOperand(i).isExpr())
619          AddValueSymbols(Inst.getOperand(i).getExpr());
620    }
621    virtual void EmitLabel(MCSymbol *Symbol) {
622      Symbol->setSection(*getCurrentSection().first);
623      markDefined(*Symbol);
624    }
625    virtual void EmitDebugLabel(MCSymbol *Symbol) {
626      EmitLabel(Symbol);
627    }
628    virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
629      // FIXME: should we handle aliases?
630      markDefined(*Symbol);
631    }
632    virtual bool EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) {
633      if (Attribute == MCSA_Global)
634        markGlobal(*Symbol);
635      return true;
636    }
637    virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
638                              uint64_t Size , unsigned ByteAlignment) {
639      markDefined(*Symbol);
640    }
641    virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
642                                  unsigned ByteAlignment) {
643      markDefined(*Symbol);
644    }
645
646    virtual void EmitBundleAlignMode(unsigned AlignPow2) {}
647    virtual void EmitBundleLock(bool AlignToEnd) {}
648    virtual void EmitBundleUnlock() {}
649
650    // Noop calls.
651    virtual void ChangeSection(const MCSection *Section,
652                               const MCExpr *Subsection) {}
653    virtual void InitToTextSection() {}
654    virtual void InitSections() {}
655    virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) {}
656    virtual void EmitThumbFunc(MCSymbol *Func) {}
657    virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {}
658    virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {}
659    virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {}
660    virtual void EmitCOFFSymbolStorageClass(int StorageClass) {}
661    virtual void EmitCOFFSymbolType(int Type) {}
662    virtual void EndCOFFSymbolDef() {}
663    virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
664    virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
665                                       unsigned ByteAlignment) {}
666    virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
667                                uint64_t Size, unsigned ByteAlignment) {}
668    virtual void EmitBytes(StringRef Data) {}
669    virtual void EmitValueImpl(const MCExpr *Value, unsigned Size) {}
670    virtual void EmitULEB128Value(const MCExpr *Value) {}
671    virtual void EmitSLEB128Value(const MCExpr *Value) {}
672    virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
673                                      unsigned ValueSize,
674                                      unsigned MaxBytesToEmit) {}
675    virtual void EmitCodeAlignment(unsigned ByteAlignment,
676                                   unsigned MaxBytesToEmit) {}
677    virtual bool EmitValueToOffset(const MCExpr *Offset,
678                                   unsigned char Value ) { return false; }
679    virtual void EmitFileDirective(StringRef Filename) {}
680    virtual void EmitDwarfAdvanceLineAddr(int64_t LineDelta,
681                                          const MCSymbol *LastLabel,
682                                          const MCSymbol *Label,
683                                          unsigned PointerSize) {}
684    virtual void FinishImpl() {}
685    virtual void EmitCFIEndProcImpl(MCDwarfFrameInfo &Frame) {
686      RecordProcEnd(Frame);
687    }
688  };
689} // end anonymous namespace
690
691/// addAsmGlobalSymbols - Add global symbols from module-level ASM to the
692/// defined or undefined lists.
693bool LTOModule::addAsmGlobalSymbols(std::string &errMsg) {
694  const std::string &inlineAsm = _module->getModuleInlineAsm();
695  if (inlineAsm.empty())
696    return false;
697
698  OwningPtr<RecordStreamer> Streamer(new RecordStreamer(_context));
699  MemoryBuffer *Buffer = MemoryBuffer::getMemBuffer(inlineAsm);
700  SourceMgr SrcMgr;
701  SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
702  OwningPtr<MCAsmParser> Parser(createMCAsmParser(SrcMgr,
703                                                  _context, *Streamer,
704                                                  *_target->getMCAsmInfo()));
705  const Target &T = _target->getTarget();
706  OwningPtr<MCInstrInfo> MCII(T.createMCInstrInfo());
707  OwningPtr<MCSubtargetInfo>
708    STI(T.createMCSubtargetInfo(_target->getTargetTriple(),
709                                _target->getTargetCPU(),
710                                _target->getTargetFeatureString()));
711  OwningPtr<MCTargetAsmParser> TAP(T.createMCAsmParser(*STI, *Parser.get(), *MCII));
712  if (!TAP) {
713    errMsg = "target " + std::string(T.getName()) +
714      " does not define AsmParser.";
715    return true;
716  }
717
718  Parser->setTargetParser(*TAP);
719  if (Parser->Run(false))
720    return true;
721
722  for (RecordStreamer::const_iterator i = Streamer->begin(),
723         e = Streamer->end(); i != e; ++i) {
724    StringRef Key = i->first();
725    RecordStreamer::State Value = i->second;
726    if (Value == RecordStreamer::DefinedGlobal)
727      addAsmGlobalSymbol(Key.data(), LTO_SYMBOL_SCOPE_DEFAULT);
728    else if (Value == RecordStreamer::Defined)
729      addAsmGlobalSymbol(Key.data(), LTO_SYMBOL_SCOPE_INTERNAL);
730    else if (Value == RecordStreamer::Global ||
731             Value == RecordStreamer::Used)
732      addAsmGlobalSymbolUndef(Key.data());
733  }
734
735  return false;
736}
737
738/// isDeclaration - Return 'true' if the global value is a declaration.
739static bool isDeclaration(const GlobalValue &V) {
740  if (V.hasAvailableExternallyLinkage())
741    return true;
742
743  if (V.isMaterializable())
744    return false;
745
746  return V.isDeclaration();
747}
748
749/// parseSymbols - Parse the symbols from the module and model-level ASM and add
750/// them to either the defined or undefined lists.
751bool LTOModule::parseSymbols(std::string &errMsg) {
752  // add functions
753  for (Module::iterator f = _module->begin(), e = _module->end(); f != e; ++f) {
754    if (isDeclaration(*f))
755      addPotentialUndefinedSymbol(f, true);
756    else
757      addDefinedFunctionSymbol(f);
758  }
759
760  // add data
761  for (Module::global_iterator v = _module->global_begin(),
762         e = _module->global_end(); v !=  e; ++v) {
763    if (isDeclaration(*v))
764      addPotentialUndefinedSymbol(v, false);
765    else
766      addDefinedDataSymbol(v);
767  }
768
769  // add asm globals
770  if (addAsmGlobalSymbols(errMsg))
771    return true;
772
773  // add aliases
774  for (Module::alias_iterator a = _module->alias_begin(),
775         e = _module->alias_end(); a != e; ++a) {
776    if (isDeclaration(*a->getAliasedGlobal()))
777      // Is an alias to a declaration.
778      addPotentialUndefinedSymbol(a, false);
779    else
780      addDefinedDataSymbol(a);
781  }
782
783  // make symbols for all undefines
784  for (StringMap<NameAndAttributes>::iterator u =_undefines.begin(),
785         e = _undefines.end(); u != e; ++u) {
786    // If this symbol also has a definition, then don't make an undefine because
787    // it is a tentative definition.
788    if (_defines.count(u->getKey())) continue;
789    NameAndAttributes info = u->getValue();
790    _symbols.push_back(info);
791  }
792
793  return false;
794}
795