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/CommandLine.h"
30#include "llvm/Support/Host.h"
31#include "llvm/Support/MemoryBuffer.h"
32#include "llvm/Support/Path.h"
33#include "llvm/Support/SourceMgr.h"
34#include "llvm/Support/TargetRegistry.h"
35#include "llvm/Support/TargetSelect.h"
36#include "llvm/Support/system_error.h"
37#include "llvm/ADT/OwningPtr.h"
38#include "llvm/ADT/Triple.h"
39using namespace llvm;
40
41static cl::opt<bool>
42EnableFPMAD("enable-fp-mad",
43  cl::desc("Enable less precise MAD instructions to be generated"),
44  cl::init(false));
45
46static cl::opt<bool>
47DisableFPElim("disable-fp-elim",
48  cl::desc("Disable frame pointer elimination optimization"),
49  cl::init(false));
50
51static cl::opt<bool>
52DisableFPElimNonLeaf("disable-non-leaf-fp-elim",
53  cl::desc("Disable frame pointer elimination optimization for non-leaf funcs"),
54  cl::init(false));
55
56static cl::opt<bool>
57EnableUnsafeFPMath("enable-unsafe-fp-math",
58  cl::desc("Enable optimizations that may decrease FP precision"),
59  cl::init(false));
60
61static cl::opt<bool>
62EnableNoInfsFPMath("enable-no-infs-fp-math",
63  cl::desc("Enable FP math optimizations that assume no +-Infs"),
64  cl::init(false));
65
66static cl::opt<bool>
67EnableNoNaNsFPMath("enable-no-nans-fp-math",
68  cl::desc("Enable FP math optimizations that assume no NaNs"),
69  cl::init(false));
70
71static cl::opt<bool>
72EnableHonorSignDependentRoundingFPMath("enable-sign-dependent-rounding-fp-math",
73  cl::Hidden,
74  cl::desc("Force codegen to assume rounding mode can change dynamically"),
75  cl::init(false));
76
77static cl::opt<bool>
78GenerateSoftFloatCalls("soft-float",
79  cl::desc("Generate software floating point library calls"),
80  cl::init(false));
81
82static cl::opt<llvm::FloatABI::ABIType>
83FloatABIForCalls("float-abi",
84  cl::desc("Choose float ABI type"),
85  cl::init(FloatABI::Default),
86  cl::values(
87    clEnumValN(FloatABI::Default, "default",
88               "Target default float ABI type"),
89    clEnumValN(FloatABI::Soft, "soft",
90               "Soft float ABI (implied by -soft-float)"),
91    clEnumValN(FloatABI::Hard, "hard",
92               "Hard float ABI (uses FP registers)"),
93    clEnumValEnd));
94
95static cl::opt<llvm::FPOpFusion::FPOpFusionMode>
96FuseFPOps("fp-contract",
97  cl::desc("Enable aggresive formation of fused FP ops"),
98  cl::init(FPOpFusion::Standard),
99  cl::values(
100    clEnumValN(FPOpFusion::Fast, "fast",
101               "Fuse FP ops whenever profitable"),
102    clEnumValN(FPOpFusion::Standard, "on",
103               "Only fuse 'blessed' FP ops."),
104    clEnumValN(FPOpFusion::Strict, "off",
105               "Only fuse FP ops when the result won't be effected."),
106    clEnumValEnd));
107
108static cl::opt<bool>
109DontPlaceZerosInBSS("nozero-initialized-in-bss",
110  cl::desc("Don't place zero-initialized symbols into bss section"),
111  cl::init(false));
112
113static cl::opt<bool>
114EnableGuaranteedTailCallOpt("tailcallopt",
115  cl::desc("Turn fastcc calls into tail calls by (potentially) changing ABI."),
116  cl::init(false));
117
118static cl::opt<bool>
119DisableTailCalls("disable-tail-calls",
120  cl::desc("Never emit tail calls"),
121  cl::init(false));
122
123static cl::opt<unsigned>
124OverrideStackAlignment("stack-alignment",
125  cl::desc("Override default stack alignment"),
126  cl::init(0));
127
128static cl::opt<bool>
129EnableRealignStack("realign-stack",
130  cl::desc("Realign stack if needed"),
131  cl::init(true));
132
133static cl::opt<std::string>
134TrapFuncName("trap-func", cl::Hidden,
135  cl::desc("Emit a call to trap function rather than a trap instruction"),
136  cl::init(""));
137
138static cl::opt<bool>
139EnablePIE("enable-pie",
140  cl::desc("Assume the creation of a position independent executable."),
141  cl::init(false));
142
143static cl::opt<bool>
144SegmentedStacks("segmented-stacks",
145  cl::desc("Use segmented stacks if possible."),
146  cl::init(false));
147
148static cl::opt<bool>
149UseInitArray("use-init-array",
150  cl::desc("Use .init_array instead of .ctors."),
151  cl::init(false));
152
153static cl::opt<unsigned>
154SSPBufferSize("stack-protector-buffer-size", cl::init(8),
155              cl::desc("Lower bound for a buffer to be considered for "
156                       "stack protection"));
157
158LTOModule::LTOModule(llvm::Module *m, llvm::TargetMachine *t)
159  : _module(m), _target(t),
160    _context(*_target->getMCAsmInfo(), *_target->getRegisterInfo(), NULL),
161    _mangler(_context, *_target->getTargetData()) {}
162
163/// isBitcodeFile - Returns 'true' if the file (or memory contents) is LLVM
164/// bitcode.
165bool LTOModule::isBitcodeFile(const void *mem, size_t length) {
166  return llvm::sys::IdentifyFileType((const char*)mem, length)
167    == llvm::sys::Bitcode_FileType;
168}
169
170bool LTOModule::isBitcodeFile(const char *path) {
171  return llvm::sys::Path(path).isBitcodeFile();
172}
173
174/// isBitcodeFileForTarget - Returns 'true' if the file (or memory contents) is
175/// LLVM bitcode for the specified triple.
176bool LTOModule::isBitcodeFileForTarget(const void *mem, size_t length,
177                                       const char *triplePrefix) {
178  MemoryBuffer *buffer = makeBuffer(mem, length);
179  if (!buffer)
180    return false;
181  return isTargetMatch(buffer, triplePrefix);
182}
183
184bool LTOModule::isBitcodeFileForTarget(const char *path,
185                                       const char *triplePrefix) {
186  OwningPtr<MemoryBuffer> buffer;
187  if (MemoryBuffer::getFile(path, buffer))
188    return false;
189  return isTargetMatch(buffer.take(), triplePrefix);
190}
191
192/// isTargetMatch - Returns 'true' if the memory buffer is for the specified
193/// target triple.
194bool LTOModule::isTargetMatch(MemoryBuffer *buffer, const char *triplePrefix) {
195  std::string Triple = getBitcodeTargetTriple(buffer, getGlobalContext());
196  delete buffer;
197  return strncmp(Triple.c_str(), triplePrefix, strlen(triplePrefix)) == 0;
198}
199
200/// makeLTOModule - Create an LTOModule. N.B. These methods take ownership of
201/// the buffer.
202LTOModule *LTOModule::makeLTOModule(const char *path, std::string &errMsg) {
203  OwningPtr<MemoryBuffer> buffer;
204  if (error_code ec = MemoryBuffer::getFile(path, buffer)) {
205    errMsg = ec.message();
206    return NULL;
207  }
208  return makeLTOModule(buffer.take(), errMsg);
209}
210
211LTOModule *LTOModule::makeLTOModule(int fd, const char *path,
212                                    size_t size, std::string &errMsg) {
213  return makeLTOModule(fd, path, size, size, 0, errMsg);
214}
215
216LTOModule *LTOModule::makeLTOModule(int fd, const char *path,
217                                    size_t file_size,
218                                    size_t map_size,
219                                    off_t offset,
220                                    std::string &errMsg) {
221  OwningPtr<MemoryBuffer> buffer;
222  if (error_code ec = MemoryBuffer::getOpenFile(fd, path, buffer, file_size,
223                                                map_size, offset, false)) {
224    errMsg = ec.message();
225    return NULL;
226  }
227  return makeLTOModule(buffer.take(), errMsg);
228}
229
230LTOModule *LTOModule::makeLTOModule(const void *mem, size_t length,
231                                    std::string &errMsg) {
232  OwningPtr<MemoryBuffer> buffer(makeBuffer(mem, length));
233  if (!buffer)
234    return NULL;
235  return makeLTOModule(buffer.take(), errMsg);
236}
237
238void LTOModule::getTargetOptions(TargetOptions &Options) {
239  Options.LessPreciseFPMADOption = EnableFPMAD;
240  Options.NoFramePointerElim = DisableFPElim;
241  Options.NoFramePointerElimNonLeaf = DisableFPElimNonLeaf;
242  Options.AllowFPOpFusion = FuseFPOps;
243  Options.UnsafeFPMath = EnableUnsafeFPMath;
244  Options.NoInfsFPMath = EnableNoInfsFPMath;
245  Options.NoNaNsFPMath = EnableNoNaNsFPMath;
246  Options.HonorSignDependentRoundingFPMathOption =
247    EnableHonorSignDependentRoundingFPMath;
248  Options.UseSoftFloat = GenerateSoftFloatCalls;
249  if (FloatABIForCalls != FloatABI::Default)
250    Options.FloatABIType = FloatABIForCalls;
251  Options.NoZerosInBSS = DontPlaceZerosInBSS;
252  Options.GuaranteedTailCallOpt = EnableGuaranteedTailCallOpt;
253  Options.DisableTailCalls = DisableTailCalls;
254  Options.StackAlignmentOverride = OverrideStackAlignment;
255  Options.RealignStack = EnableRealignStack;
256  Options.TrapFuncName = TrapFuncName;
257  Options.PositionIndependentExecutable = EnablePIE;
258  Options.EnableSegmentedStacks = SegmentedStacks;
259  Options.UseInitArray = UseInitArray;
260  Options.SSPBufferSize = SSPBufferSize;
261}
262
263LTOModule *LTOModule::makeLTOModule(MemoryBuffer *buffer,
264                                    std::string &errMsg) {
265  static bool Initialized = false;
266  if (!Initialized) {
267    InitializeAllTargets();
268    InitializeAllTargetMCs();
269    InitializeAllAsmParsers();
270    Initialized = true;
271  }
272
273  // parse bitcode buffer
274  OwningPtr<Module> m(getLazyBitcodeModule(buffer, getGlobalContext(),
275                                           &errMsg));
276  if (!m) {
277    delete buffer;
278    return NULL;
279  }
280
281  std::string Triple = m->getTargetTriple();
282  if (Triple.empty())
283    Triple = sys::getDefaultTargetTriple();
284
285  // find machine architecture for this module
286  const Target *march = TargetRegistry::lookupTarget(Triple, errMsg);
287  if (!march)
288    return NULL;
289
290  // construct LTOModule, hand over ownership of module and target
291  SubtargetFeatures Features;
292  Features.getDefaultSubtargetFeatures(llvm::Triple(Triple));
293  std::string FeatureStr = Features.getString();
294  std::string CPU;
295  TargetOptions Options;
296  getTargetOptions(Options);
297  TargetMachine *target = march->createTargetMachine(Triple, CPU, FeatureStr,
298                                                     Options);
299  LTOModule *Ret = new LTOModule(m.take(), target);
300  if (Ret->parseSymbols(errMsg)) {
301    delete Ret;
302    return NULL;
303  }
304
305  return Ret;
306}
307
308/// makeBuffer - Create a MemoryBuffer from a memory range.
309MemoryBuffer *LTOModule::makeBuffer(const void *mem, size_t length) {
310  const char *startPtr = (const char*)mem;
311  return MemoryBuffer::getMemBuffer(StringRef(startPtr, length), "", false);
312}
313
314/// objcClassNameFromExpression - Get string that the data pointer points to.
315bool LTOModule::objcClassNameFromExpression(Constant *c, std::string &name) {
316  if (ConstantExpr *ce = dyn_cast<ConstantExpr>(c)) {
317    Constant *op = ce->getOperand(0);
318    if (GlobalVariable *gvn = dyn_cast<GlobalVariable>(op)) {
319      Constant *cn = gvn->getInitializer();
320      if (ConstantDataArray *ca = dyn_cast<ConstantDataArray>(cn)) {
321        if (ca->isCString()) {
322          name = ".objc_class_name_" + ca->getAsCString().str();
323          return true;
324        }
325      }
326    }
327  }
328  return false;
329}
330
331/// addObjCClass - Parse i386/ppc ObjC class data structure.
332void LTOModule::addObjCClass(GlobalVariable *clgv) {
333  ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer());
334  if (!c) return;
335
336  // second slot in __OBJC,__class is pointer to superclass name
337  std::string superclassName;
338  if (objcClassNameFromExpression(c->getOperand(1), superclassName)) {
339    NameAndAttributes info;
340    StringMap<NameAndAttributes>::value_type &entry =
341      _undefines.GetOrCreateValue(superclassName);
342    if (!entry.getValue().name) {
343      const char *symbolName = entry.getKey().data();
344      info.name = symbolName;
345      info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
346      info.isFunction = false;
347      info.symbol = clgv;
348      entry.setValue(info);
349    }
350  }
351
352  // third slot in __OBJC,__class is pointer to class name
353  std::string className;
354  if (objcClassNameFromExpression(c->getOperand(2), className)) {
355    StringSet::value_type &entry = _defines.GetOrCreateValue(className);
356    entry.setValue(1);
357
358    NameAndAttributes info;
359    info.name = entry.getKey().data();
360    info.attributes = LTO_SYMBOL_PERMISSIONS_DATA |
361      LTO_SYMBOL_DEFINITION_REGULAR | LTO_SYMBOL_SCOPE_DEFAULT;
362    info.isFunction = false;
363    info.symbol = clgv;
364    _symbols.push_back(info);
365  }
366}
367
368/// addObjCCategory - Parse i386/ppc ObjC category data structure.
369void LTOModule::addObjCCategory(GlobalVariable *clgv) {
370  ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer());
371  if (!c) return;
372
373  // second slot in __OBJC,__category is pointer to target class name
374  std::string targetclassName;
375  if (!objcClassNameFromExpression(c->getOperand(1), targetclassName))
376    return;
377
378  NameAndAttributes info;
379  StringMap<NameAndAttributes>::value_type &entry =
380    _undefines.GetOrCreateValue(targetclassName);
381
382  if (entry.getValue().name)
383    return;
384
385  const char *symbolName = entry.getKey().data();
386  info.name = symbolName;
387  info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
388  info.isFunction = false;
389  info.symbol = clgv;
390  entry.setValue(info);
391}
392
393/// addObjCClassRef - Parse i386/ppc ObjC class list data structure.
394void LTOModule::addObjCClassRef(GlobalVariable *clgv) {
395  std::string targetclassName;
396  if (!objcClassNameFromExpression(clgv->getInitializer(), targetclassName))
397    return;
398
399  NameAndAttributes info;
400  StringMap<NameAndAttributes>::value_type &entry =
401    _undefines.GetOrCreateValue(targetclassName);
402  if (entry.getValue().name)
403    return;
404
405  const char *symbolName = entry.getKey().data();
406  info.name = symbolName;
407  info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
408  info.isFunction = false;
409  info.symbol = clgv;
410  entry.setValue(info);
411}
412
413/// addDefinedDataSymbol - Add a data symbol as defined to the list.
414void LTOModule::addDefinedDataSymbol(GlobalValue *v) {
415  // Add to list of defined symbols.
416  addDefinedSymbol(v, false);
417
418  if (!v->hasSection() /* || !isTargetDarwin */)
419    return;
420
421  // Special case i386/ppc ObjC data structures in magic sections:
422  // The issue is that the old ObjC object format did some strange
423  // contortions to avoid real linker symbols.  For instance, the
424  // ObjC class data structure is allocated statically in the executable
425  // that defines that class.  That data structures contains a pointer to
426  // its superclass.  But instead of just initializing that part of the
427  // struct to the address of its superclass, and letting the static and
428  // dynamic linkers do the rest, the runtime works by having that field
429  // instead point to a C-string that is the name of the superclass.
430  // At runtime the objc initialization updates that pointer and sets
431  // it to point to the actual super class.  As far as the linker
432  // knows it is just a pointer to a string.  But then someone wanted the
433  // linker to issue errors at build time if the superclass was not found.
434  // So they figured out a way in mach-o object format to use an absolute
435  // symbols (.objc_class_name_Foo = 0) and a floating reference
436  // (.reference .objc_class_name_Bar) to cause the linker into erroring when
437  // a class was missing.
438  // The following synthesizes the implicit .objc_* symbols for the linker
439  // from the ObjC data structures generated by the front end.
440
441  // special case if this data blob is an ObjC class definition
442  if (v->getSection().compare(0, 15, "__OBJC,__class,") == 0) {
443    if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
444      addObjCClass(gv);
445    }
446  }
447
448  // special case if this data blob is an ObjC category definition
449  else if (v->getSection().compare(0, 18, "__OBJC,__category,") == 0) {
450    if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
451      addObjCCategory(gv);
452    }
453  }
454
455  // special case if this data blob is the list of referenced classes
456  else if (v->getSection().compare(0, 18, "__OBJC,__cls_refs,") == 0) {
457    if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
458      addObjCClassRef(gv);
459    }
460  }
461}
462
463/// addDefinedFunctionSymbol - Add a function symbol as defined to the list.
464void LTOModule::addDefinedFunctionSymbol(Function *f) {
465  // add to list of defined symbols
466  addDefinedSymbol(f, true);
467}
468
469/// addDefinedSymbol - Add a defined symbol to the list.
470void LTOModule::addDefinedSymbol(GlobalValue *def, bool isFunction) {
471  // ignore all llvm.* symbols
472  if (def->getName().startswith("llvm."))
473    return;
474
475  // string is owned by _defines
476  SmallString<64> Buffer;
477  _mangler.getNameWithPrefix(Buffer, def, false);
478
479  // set alignment part log2() can have rounding errors
480  uint32_t align = def->getAlignment();
481  uint32_t attr = align ? CountTrailingZeros_32(def->getAlignment()) : 0;
482
483  // set permissions part
484  if (isFunction) {
485    attr |= LTO_SYMBOL_PERMISSIONS_CODE;
486  } else {
487    GlobalVariable *gv = dyn_cast<GlobalVariable>(def);
488    if (gv && gv->isConstant())
489      attr |= LTO_SYMBOL_PERMISSIONS_RODATA;
490    else
491      attr |= LTO_SYMBOL_PERMISSIONS_DATA;
492  }
493
494  // set definition part
495  if (def->hasWeakLinkage() || def->hasLinkOnceLinkage() ||
496      def->hasLinkerPrivateWeakLinkage())
497    attr |= LTO_SYMBOL_DEFINITION_WEAK;
498  else if (def->hasCommonLinkage())
499    attr |= LTO_SYMBOL_DEFINITION_TENTATIVE;
500  else
501    attr |= LTO_SYMBOL_DEFINITION_REGULAR;
502
503  // set scope part
504  if (def->hasHiddenVisibility())
505    attr |= LTO_SYMBOL_SCOPE_HIDDEN;
506  else if (def->hasProtectedVisibility())
507    attr |= LTO_SYMBOL_SCOPE_PROTECTED;
508  else if (def->hasExternalLinkage() || def->hasWeakLinkage() ||
509           def->hasLinkOnceLinkage() || def->hasCommonLinkage() ||
510           def->hasLinkerPrivateWeakLinkage())
511    attr |= LTO_SYMBOL_SCOPE_DEFAULT;
512  else if (def->hasLinkOnceODRAutoHideLinkage())
513    attr |= LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
514  else
515    attr |= LTO_SYMBOL_SCOPE_INTERNAL;
516
517  StringSet::value_type &entry = _defines.GetOrCreateValue(Buffer);
518  entry.setValue(1);
519
520  // fill information structure
521  NameAndAttributes info;
522  StringRef Name = entry.getKey();
523  info.name = Name.data();
524  assert(info.name[Name.size()] == '\0');
525  info.attributes = attr;
526  info.isFunction = isFunction;
527  info.symbol = def;
528
529  // add to table of symbols
530  _symbols.push_back(info);
531}
532
533/// addAsmGlobalSymbol - Add a global symbol from module-level ASM to the
534/// defined list.
535void LTOModule::addAsmGlobalSymbol(const char *name,
536                                   lto_symbol_attributes scope) {
537  StringSet::value_type &entry = _defines.GetOrCreateValue(name);
538
539  // only add new define if not already defined
540  if (entry.getValue())
541    return;
542
543  entry.setValue(1);
544
545  NameAndAttributes &info = _undefines[entry.getKey().data()];
546
547  if (info.symbol == 0) {
548    // FIXME: This is trying to take care of module ASM like this:
549    //
550    //   module asm ".zerofill __FOO, __foo, _bar_baz_qux, 0"
551    //
552    // but is gross and its mother dresses it funny. Have the ASM parser give us
553    // more details for this type of situation so that we're not guessing so
554    // much.
555
556    // fill information structure
557    info.name = entry.getKey().data();
558    info.attributes =
559      LTO_SYMBOL_PERMISSIONS_DATA | LTO_SYMBOL_DEFINITION_REGULAR | scope;
560    info.isFunction = false;
561    info.symbol = 0;
562
563    // add to table of symbols
564    _symbols.push_back(info);
565    return;
566  }
567
568  if (info.isFunction)
569    addDefinedFunctionSymbol(cast<Function>(info.symbol));
570  else
571    addDefinedDataSymbol(info.symbol);
572
573  _symbols.back().attributes &= ~LTO_SYMBOL_SCOPE_MASK;
574  _symbols.back().attributes |= scope;
575}
576
577/// addAsmGlobalSymbolUndef - Add a global symbol from module-level ASM to the
578/// undefined list.
579void LTOModule::addAsmGlobalSymbolUndef(const char *name) {
580  StringMap<NameAndAttributes>::value_type &entry =
581    _undefines.GetOrCreateValue(name);
582
583  _asm_undefines.push_back(entry.getKey().data());
584
585  // we already have the symbol
586  if (entry.getValue().name)
587    return;
588
589  uint32_t attr = LTO_SYMBOL_DEFINITION_UNDEFINED;;
590  attr |= LTO_SYMBOL_SCOPE_DEFAULT;
591  NameAndAttributes info;
592  info.name = entry.getKey().data();
593  info.attributes = attr;
594  info.isFunction = false;
595  info.symbol = 0;
596
597  entry.setValue(info);
598}
599
600/// addPotentialUndefinedSymbol - Add a symbol which isn't defined just yet to a
601/// list to be resolved later.
602void LTOModule::addPotentialUndefinedSymbol(GlobalValue *decl, bool isFunc) {
603  // ignore all llvm.* symbols
604  if (decl->getName().startswith("llvm."))
605    return;
606
607  // ignore all aliases
608  if (isa<GlobalAlias>(decl))
609    return;
610
611  SmallString<64> name;
612  _mangler.getNameWithPrefix(name, decl, false);
613
614  StringMap<NameAndAttributes>::value_type &entry =
615    _undefines.GetOrCreateValue(name);
616
617  // we already have the symbol
618  if (entry.getValue().name)
619    return;
620
621  NameAndAttributes info;
622
623  info.name = entry.getKey().data();
624
625  if (decl->hasExternalWeakLinkage())
626    info.attributes = LTO_SYMBOL_DEFINITION_WEAKUNDEF;
627  else
628    info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
629
630  info.isFunction = isFunc;
631  info.symbol = decl;
632
633  entry.setValue(info);
634}
635
636namespace {
637  class RecordStreamer : public MCStreamer {
638  public:
639    enum State { NeverSeen, Global, Defined, DefinedGlobal, Used };
640
641  private:
642    StringMap<State> Symbols;
643
644    void markDefined(const MCSymbol &Symbol) {
645      State &S = Symbols[Symbol.getName()];
646      switch (S) {
647      case DefinedGlobal:
648      case Global:
649        S = DefinedGlobal;
650        break;
651      case NeverSeen:
652      case Defined:
653      case Used:
654        S = Defined;
655        break;
656      }
657    }
658    void markGlobal(const MCSymbol &Symbol) {
659      State &S = Symbols[Symbol.getName()];
660      switch (S) {
661      case DefinedGlobal:
662      case Defined:
663        S = DefinedGlobal;
664        break;
665
666      case NeverSeen:
667      case Global:
668      case Used:
669        S = Global;
670        break;
671      }
672    }
673    void markUsed(const MCSymbol &Symbol) {
674      State &S = Symbols[Symbol.getName()];
675      switch (S) {
676      case DefinedGlobal:
677      case Defined:
678      case Global:
679        break;
680
681      case NeverSeen:
682      case Used:
683        S = Used;
684        break;
685      }
686    }
687
688    // FIXME: mostly copied for the obj streamer.
689    void AddValueSymbols(const MCExpr *Value) {
690      switch (Value->getKind()) {
691      case MCExpr::Target:
692        // FIXME: What should we do in here?
693        break;
694
695      case MCExpr::Constant:
696        break;
697
698      case MCExpr::Binary: {
699        const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
700        AddValueSymbols(BE->getLHS());
701        AddValueSymbols(BE->getRHS());
702        break;
703      }
704
705      case MCExpr::SymbolRef:
706        markUsed(cast<MCSymbolRefExpr>(Value)->getSymbol());
707        break;
708
709      case MCExpr::Unary:
710        AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
711        break;
712      }
713    }
714
715  public:
716    typedef StringMap<State>::const_iterator const_iterator;
717
718    const_iterator begin() {
719      return Symbols.begin();
720    }
721
722    const_iterator end() {
723      return Symbols.end();
724    }
725
726    RecordStreamer(MCContext &Context) : MCStreamer(Context) {}
727
728    virtual void EmitInstruction(const MCInst &Inst) {
729      // Scan for values.
730      for (unsigned i = Inst.getNumOperands(); i--; )
731        if (Inst.getOperand(i).isExpr())
732          AddValueSymbols(Inst.getOperand(i).getExpr());
733    }
734    virtual void EmitLabel(MCSymbol *Symbol) {
735      Symbol->setSection(*getCurrentSection());
736      markDefined(*Symbol);
737    }
738    virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
739      // FIXME: should we handle aliases?
740      markDefined(*Symbol);
741    }
742    virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) {
743      if (Attribute == MCSA_Global)
744        markGlobal(*Symbol);
745    }
746    virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
747                              uint64_t Size , unsigned ByteAlignment) {
748      markDefined(*Symbol);
749    }
750    virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
751                                  unsigned ByteAlignment) {
752      markDefined(*Symbol);
753    }
754
755    // Noop calls.
756    virtual void ChangeSection(const MCSection *Section) {}
757    virtual void InitSections() {}
758    virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) {}
759    virtual void EmitThumbFunc(MCSymbol *Func) {}
760    virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {}
761    virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {}
762    virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {}
763    virtual void EmitCOFFSymbolStorageClass(int StorageClass) {}
764    virtual void EmitCOFFSymbolType(int Type) {}
765    virtual void EndCOFFSymbolDef() {}
766    virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
767    virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
768                                       unsigned ByteAlignment) {}
769    virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
770                                uint64_t Size, unsigned ByteAlignment) {}
771    virtual void EmitBytes(StringRef Data, unsigned AddrSpace) {}
772    virtual void EmitValueImpl(const MCExpr *Value, unsigned Size,
773                               unsigned AddrSpace) {}
774    virtual void EmitULEB128Value(const MCExpr *Value) {}
775    virtual void EmitSLEB128Value(const MCExpr *Value) {}
776    virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
777                                      unsigned ValueSize,
778                                      unsigned MaxBytesToEmit) {}
779    virtual void EmitCodeAlignment(unsigned ByteAlignment,
780                                   unsigned MaxBytesToEmit) {}
781    virtual bool EmitValueToOffset(const MCExpr *Offset,
782                                   unsigned char Value ) { return false; }
783    virtual void EmitFileDirective(StringRef Filename) {}
784    virtual void EmitDwarfAdvanceLineAddr(int64_t LineDelta,
785                                          const MCSymbol *LastLabel,
786                                          const MCSymbol *Label,
787                                          unsigned PointerSize) {}
788    virtual void FinishImpl() {}
789  };
790} // end anonymous namespace
791
792/// addAsmGlobalSymbols - Add global symbols from module-level ASM to the
793/// defined or undefined lists.
794bool LTOModule::addAsmGlobalSymbols(std::string &errMsg) {
795  const std::string &inlineAsm = _module->getModuleInlineAsm();
796  if (inlineAsm.empty())
797    return false;
798
799  OwningPtr<RecordStreamer> Streamer(new RecordStreamer(_context));
800  MemoryBuffer *Buffer = MemoryBuffer::getMemBuffer(inlineAsm);
801  SourceMgr SrcMgr;
802  SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
803  OwningPtr<MCAsmParser> Parser(createMCAsmParser(SrcMgr,
804                                                  _context, *Streamer,
805                                                  *_target->getMCAsmInfo()));
806  const Target &T = _target->getTarget();
807  OwningPtr<MCSubtargetInfo>
808    STI(T.createMCSubtargetInfo(_target->getTargetTriple(),
809                                _target->getTargetCPU(),
810                                _target->getTargetFeatureString()));
811  OwningPtr<MCTargetAsmParser> TAP(T.createMCAsmParser(*STI, *Parser.get()));
812  if (!TAP) {
813    errMsg = "target " + std::string(T.getName()) +
814      " does not define AsmParser.";
815    return true;
816  }
817
818  Parser->setTargetParser(*TAP);
819  if (Parser->Run(false))
820    return true;
821
822  for (RecordStreamer::const_iterator i = Streamer->begin(),
823         e = Streamer->end(); i != e; ++i) {
824    StringRef Key = i->first();
825    RecordStreamer::State Value = i->second;
826    if (Value == RecordStreamer::DefinedGlobal)
827      addAsmGlobalSymbol(Key.data(), LTO_SYMBOL_SCOPE_DEFAULT);
828    else if (Value == RecordStreamer::Defined)
829      addAsmGlobalSymbol(Key.data(), LTO_SYMBOL_SCOPE_INTERNAL);
830    else if (Value == RecordStreamer::Global ||
831             Value == RecordStreamer::Used)
832      addAsmGlobalSymbolUndef(Key.data());
833  }
834
835  return false;
836}
837
838/// isDeclaration - Return 'true' if the global value is a declaration.
839static bool isDeclaration(const GlobalValue &V) {
840  if (V.hasAvailableExternallyLinkage())
841    return true;
842
843  if (V.isMaterializable())
844    return false;
845
846  return V.isDeclaration();
847}
848
849/// parseSymbols - Parse the symbols from the module and model-level ASM and add
850/// them to either the defined or undefined lists.
851bool LTOModule::parseSymbols(std::string &errMsg) {
852  // add functions
853  for (Module::iterator f = _module->begin(), e = _module->end(); f != e; ++f) {
854    if (isDeclaration(*f))
855      addPotentialUndefinedSymbol(f, true);
856    else
857      addDefinedFunctionSymbol(f);
858  }
859
860  // add data
861  for (Module::global_iterator v = _module->global_begin(),
862         e = _module->global_end(); v !=  e; ++v) {
863    if (isDeclaration(*v))
864      addPotentialUndefinedSymbol(v, false);
865    else
866      addDefinedDataSymbol(v);
867  }
868
869  // add asm globals
870  if (addAsmGlobalSymbols(errMsg))
871    return true;
872
873  // add aliases
874  for (Module::alias_iterator a = _module->alias_begin(),
875         e = _module->alias_end(); a != e; ++a) {
876    if (isDeclaration(*a->getAliasedGlobal()))
877      // Is an alias to a declaration.
878      addPotentialUndefinedSymbol(a, false);
879    else
880      addDefinedDataSymbol(a);
881  }
882
883  // make symbols for all undefines
884  for (StringMap<NameAndAttributes>::iterator u =_undefines.begin(),
885         e = _undefines.end(); u != e; ++u) {
886    // If this symbol also has a definition, then don't make an undefine because
887    // it is a tentative definition.
888    if (_defines.count(u->getKey())) continue;
889    NameAndAttributes info = u->getValue();
890    _symbols.push_back(info);
891  }
892
893  return false;
894}
895