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 TripleStr = m->getTargetTriple();
282  if (TripleStr.empty())
283    TripleStr = sys::getDefaultTargetTriple();
284  llvm::Triple Triple(TripleStr);
285
286  // find machine architecture for this module
287  const Target *march = TargetRegistry::lookupTarget(TripleStr, errMsg);
288  if (!march)
289    return NULL;
290
291  // construct LTOModule, hand over ownership of module and target
292  SubtargetFeatures Features;
293  Features.getDefaultSubtargetFeatures(Triple);
294  std::string FeatureStr = Features.getString();
295  // Set a default CPU for Darwin triples.
296  std::string CPU;
297  if (Triple.isOSDarwin()) {
298    if (Triple.getArch() == llvm::Triple::x86_64)
299      CPU = "core2";
300    else if (Triple.getArch() == llvm::Triple::x86)
301      CPU = "yonah";
302  }
303  TargetOptions Options;
304  getTargetOptions(Options);
305  TargetMachine *target = march->createTargetMachine(TripleStr, CPU, FeatureStr,
306                                                     Options);
307  LTOModule *Ret = new LTOModule(m.take(), target);
308  if (Ret->parseSymbols(errMsg)) {
309    delete Ret;
310    return NULL;
311  }
312
313  return Ret;
314}
315
316/// makeBuffer - Create a MemoryBuffer from a memory range.
317MemoryBuffer *LTOModule::makeBuffer(const void *mem, size_t length) {
318  const char *startPtr = (const char*)mem;
319  return MemoryBuffer::getMemBuffer(StringRef(startPtr, length), "", false);
320}
321
322/// objcClassNameFromExpression - Get string that the data pointer points to.
323bool LTOModule::objcClassNameFromExpression(Constant *c, std::string &name) {
324  if (ConstantExpr *ce = dyn_cast<ConstantExpr>(c)) {
325    Constant *op = ce->getOperand(0);
326    if (GlobalVariable *gvn = dyn_cast<GlobalVariable>(op)) {
327      Constant *cn = gvn->getInitializer();
328      if (ConstantDataArray *ca = dyn_cast<ConstantDataArray>(cn)) {
329        if (ca->isCString()) {
330          name = ".objc_class_name_" + ca->getAsCString().str();
331          return true;
332        }
333      }
334    }
335  }
336  return false;
337}
338
339/// addObjCClass - Parse i386/ppc ObjC class data structure.
340void LTOModule::addObjCClass(GlobalVariable *clgv) {
341  ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer());
342  if (!c) return;
343
344  // second slot in __OBJC,__class is pointer to superclass name
345  std::string superclassName;
346  if (objcClassNameFromExpression(c->getOperand(1), superclassName)) {
347    NameAndAttributes info;
348    StringMap<NameAndAttributes>::value_type &entry =
349      _undefines.GetOrCreateValue(superclassName);
350    if (!entry.getValue().name) {
351      const char *symbolName = entry.getKey().data();
352      info.name = symbolName;
353      info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
354      info.isFunction = false;
355      info.symbol = clgv;
356      entry.setValue(info);
357    }
358  }
359
360  // third slot in __OBJC,__class is pointer to class name
361  std::string className;
362  if (objcClassNameFromExpression(c->getOperand(2), className)) {
363    StringSet::value_type &entry = _defines.GetOrCreateValue(className);
364    entry.setValue(1);
365
366    NameAndAttributes info;
367    info.name = entry.getKey().data();
368    info.attributes = LTO_SYMBOL_PERMISSIONS_DATA |
369      LTO_SYMBOL_DEFINITION_REGULAR | LTO_SYMBOL_SCOPE_DEFAULT;
370    info.isFunction = false;
371    info.symbol = clgv;
372    _symbols.push_back(info);
373  }
374}
375
376/// addObjCCategory - Parse i386/ppc ObjC category data structure.
377void LTOModule::addObjCCategory(GlobalVariable *clgv) {
378  ConstantStruct *c = dyn_cast<ConstantStruct>(clgv->getInitializer());
379  if (!c) return;
380
381  // second slot in __OBJC,__category is pointer to target class name
382  std::string targetclassName;
383  if (!objcClassNameFromExpression(c->getOperand(1), targetclassName))
384    return;
385
386  NameAndAttributes info;
387  StringMap<NameAndAttributes>::value_type &entry =
388    _undefines.GetOrCreateValue(targetclassName);
389
390  if (entry.getValue().name)
391    return;
392
393  const char *symbolName = entry.getKey().data();
394  info.name = symbolName;
395  info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
396  info.isFunction = false;
397  info.symbol = clgv;
398  entry.setValue(info);
399}
400
401/// addObjCClassRef - Parse i386/ppc ObjC class list data structure.
402void LTOModule::addObjCClassRef(GlobalVariable *clgv) {
403  std::string targetclassName;
404  if (!objcClassNameFromExpression(clgv->getInitializer(), targetclassName))
405    return;
406
407  NameAndAttributes info;
408  StringMap<NameAndAttributes>::value_type &entry =
409    _undefines.GetOrCreateValue(targetclassName);
410  if (entry.getValue().name)
411    return;
412
413  const char *symbolName = entry.getKey().data();
414  info.name = symbolName;
415  info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
416  info.isFunction = false;
417  info.symbol = clgv;
418  entry.setValue(info);
419}
420
421/// addDefinedDataSymbol - Add a data symbol as defined to the list.
422void LTOModule::addDefinedDataSymbol(GlobalValue *v) {
423  // Add to list of defined symbols.
424  addDefinedSymbol(v, false);
425
426  if (!v->hasSection() /* || !isTargetDarwin */)
427    return;
428
429  // Special case i386/ppc ObjC data structures in magic sections:
430  // The issue is that the old ObjC object format did some strange
431  // contortions to avoid real linker symbols.  For instance, the
432  // ObjC class data structure is allocated statically in the executable
433  // that defines that class.  That data structures contains a pointer to
434  // its superclass.  But instead of just initializing that part of the
435  // struct to the address of its superclass, and letting the static and
436  // dynamic linkers do the rest, the runtime works by having that field
437  // instead point to a C-string that is the name of the superclass.
438  // At runtime the objc initialization updates that pointer and sets
439  // it to point to the actual super class.  As far as the linker
440  // knows it is just a pointer to a string.  But then someone wanted the
441  // linker to issue errors at build time if the superclass was not found.
442  // So they figured out a way in mach-o object format to use an absolute
443  // symbols (.objc_class_name_Foo = 0) and a floating reference
444  // (.reference .objc_class_name_Bar) to cause the linker into erroring when
445  // a class was missing.
446  // The following synthesizes the implicit .objc_* symbols for the linker
447  // from the ObjC data structures generated by the front end.
448
449  // special case if this data blob is an ObjC class definition
450  if (v->getSection().compare(0, 15, "__OBJC,__class,") == 0) {
451    if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
452      addObjCClass(gv);
453    }
454  }
455
456  // special case if this data blob is an ObjC category definition
457  else if (v->getSection().compare(0, 18, "__OBJC,__category,") == 0) {
458    if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
459      addObjCCategory(gv);
460    }
461  }
462
463  // special case if this data blob is the list of referenced classes
464  else if (v->getSection().compare(0, 18, "__OBJC,__cls_refs,") == 0) {
465    if (GlobalVariable *gv = dyn_cast<GlobalVariable>(v)) {
466      addObjCClassRef(gv);
467    }
468  }
469}
470
471/// addDefinedFunctionSymbol - Add a function symbol as defined to the list.
472void LTOModule::addDefinedFunctionSymbol(Function *f) {
473  // add to list of defined symbols
474  addDefinedSymbol(f, true);
475}
476
477/// addDefinedSymbol - Add a defined symbol to the list.
478void LTOModule::addDefinedSymbol(GlobalValue *def, bool isFunction) {
479  // ignore all llvm.* symbols
480  if (def->getName().startswith("llvm."))
481    return;
482
483  // string is owned by _defines
484  SmallString<64> Buffer;
485  _mangler.getNameWithPrefix(Buffer, def, false);
486
487  // set alignment part log2() can have rounding errors
488  uint32_t align = def->getAlignment();
489  uint32_t attr = align ? CountTrailingZeros_32(def->getAlignment()) : 0;
490
491  // set permissions part
492  if (isFunction) {
493    attr |= LTO_SYMBOL_PERMISSIONS_CODE;
494  } else {
495    GlobalVariable *gv = dyn_cast<GlobalVariable>(def);
496    if (gv && gv->isConstant())
497      attr |= LTO_SYMBOL_PERMISSIONS_RODATA;
498    else
499      attr |= LTO_SYMBOL_PERMISSIONS_DATA;
500  }
501
502  // set definition part
503  if (def->hasWeakLinkage() || def->hasLinkOnceLinkage() ||
504      def->hasLinkerPrivateWeakLinkage())
505    attr |= LTO_SYMBOL_DEFINITION_WEAK;
506  else if (def->hasCommonLinkage())
507    attr |= LTO_SYMBOL_DEFINITION_TENTATIVE;
508  else
509    attr |= LTO_SYMBOL_DEFINITION_REGULAR;
510
511  // set scope part
512  if (def->hasHiddenVisibility())
513    attr |= LTO_SYMBOL_SCOPE_HIDDEN;
514  else if (def->hasProtectedVisibility())
515    attr |= LTO_SYMBOL_SCOPE_PROTECTED;
516  else if (def->hasExternalLinkage() || def->hasWeakLinkage() ||
517           def->hasLinkOnceLinkage() || def->hasCommonLinkage() ||
518           def->hasLinkerPrivateWeakLinkage())
519    attr |= LTO_SYMBOL_SCOPE_DEFAULT;
520  else if (def->hasLinkOnceODRAutoHideLinkage())
521    attr |= LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN;
522  else
523    attr |= LTO_SYMBOL_SCOPE_INTERNAL;
524
525  StringSet::value_type &entry = _defines.GetOrCreateValue(Buffer);
526  entry.setValue(1);
527
528  // fill information structure
529  NameAndAttributes info;
530  StringRef Name = entry.getKey();
531  info.name = Name.data();
532  assert(info.name[Name.size()] == '\0');
533  info.attributes = attr;
534  info.isFunction = isFunction;
535  info.symbol = def;
536
537  // add to table of symbols
538  _symbols.push_back(info);
539}
540
541/// addAsmGlobalSymbol - Add a global symbol from module-level ASM to the
542/// defined list.
543void LTOModule::addAsmGlobalSymbol(const char *name,
544                                   lto_symbol_attributes scope) {
545  StringSet::value_type &entry = _defines.GetOrCreateValue(name);
546
547  // only add new define if not already defined
548  if (entry.getValue())
549    return;
550
551  entry.setValue(1);
552
553  NameAndAttributes &info = _undefines[entry.getKey().data()];
554
555  if (info.symbol == 0) {
556    // FIXME: This is trying to take care of module ASM like this:
557    //
558    //   module asm ".zerofill __FOO, __foo, _bar_baz_qux, 0"
559    //
560    // but is gross and its mother dresses it funny. Have the ASM parser give us
561    // more details for this type of situation so that we're not guessing so
562    // much.
563
564    // fill information structure
565    info.name = entry.getKey().data();
566    info.attributes =
567      LTO_SYMBOL_PERMISSIONS_DATA | LTO_SYMBOL_DEFINITION_REGULAR | scope;
568    info.isFunction = false;
569    info.symbol = 0;
570
571    // add to table of symbols
572    _symbols.push_back(info);
573    return;
574  }
575
576  if (info.isFunction)
577    addDefinedFunctionSymbol(cast<Function>(info.symbol));
578  else
579    addDefinedDataSymbol(info.symbol);
580
581  _symbols.back().attributes &= ~LTO_SYMBOL_SCOPE_MASK;
582  _symbols.back().attributes |= scope;
583}
584
585/// addAsmGlobalSymbolUndef - Add a global symbol from module-level ASM to the
586/// undefined list.
587void LTOModule::addAsmGlobalSymbolUndef(const char *name) {
588  StringMap<NameAndAttributes>::value_type &entry =
589    _undefines.GetOrCreateValue(name);
590
591  _asm_undefines.push_back(entry.getKey().data());
592
593  // we already have the symbol
594  if (entry.getValue().name)
595    return;
596
597  uint32_t attr = LTO_SYMBOL_DEFINITION_UNDEFINED;;
598  attr |= LTO_SYMBOL_SCOPE_DEFAULT;
599  NameAndAttributes info;
600  info.name = entry.getKey().data();
601  info.attributes = attr;
602  info.isFunction = false;
603  info.symbol = 0;
604
605  entry.setValue(info);
606}
607
608/// addPotentialUndefinedSymbol - Add a symbol which isn't defined just yet to a
609/// list to be resolved later.
610void LTOModule::addPotentialUndefinedSymbol(GlobalValue *decl, bool isFunc) {
611  // ignore all llvm.* symbols
612  if (decl->getName().startswith("llvm."))
613    return;
614
615  // ignore all aliases
616  if (isa<GlobalAlias>(decl))
617    return;
618
619  SmallString<64> name;
620  _mangler.getNameWithPrefix(name, decl, false);
621
622  StringMap<NameAndAttributes>::value_type &entry =
623    _undefines.GetOrCreateValue(name);
624
625  // we already have the symbol
626  if (entry.getValue().name)
627    return;
628
629  NameAndAttributes info;
630
631  info.name = entry.getKey().data();
632
633  if (decl->hasExternalWeakLinkage())
634    info.attributes = LTO_SYMBOL_DEFINITION_WEAKUNDEF;
635  else
636    info.attributes = LTO_SYMBOL_DEFINITION_UNDEFINED;
637
638  info.isFunction = isFunc;
639  info.symbol = decl;
640
641  entry.setValue(info);
642}
643
644namespace {
645  class RecordStreamer : public MCStreamer {
646  public:
647    enum State { NeverSeen, Global, Defined, DefinedGlobal, Used };
648
649  private:
650    StringMap<State> Symbols;
651
652    void markDefined(const MCSymbol &Symbol) {
653      State &S = Symbols[Symbol.getName()];
654      switch (S) {
655      case DefinedGlobal:
656      case Global:
657        S = DefinedGlobal;
658        break;
659      case NeverSeen:
660      case Defined:
661      case Used:
662        S = Defined;
663        break;
664      }
665    }
666    void markGlobal(const MCSymbol &Symbol) {
667      State &S = Symbols[Symbol.getName()];
668      switch (S) {
669      case DefinedGlobal:
670      case Defined:
671        S = DefinedGlobal;
672        break;
673
674      case NeverSeen:
675      case Global:
676      case Used:
677        S = Global;
678        break;
679      }
680    }
681    void markUsed(const MCSymbol &Symbol) {
682      State &S = Symbols[Symbol.getName()];
683      switch (S) {
684      case DefinedGlobal:
685      case Defined:
686      case Global:
687        break;
688
689      case NeverSeen:
690      case Used:
691        S = Used;
692        break;
693      }
694    }
695
696    // FIXME: mostly copied for the obj streamer.
697    void AddValueSymbols(const MCExpr *Value) {
698      switch (Value->getKind()) {
699      case MCExpr::Target:
700        // FIXME: What should we do in here?
701        break;
702
703      case MCExpr::Constant:
704        break;
705
706      case MCExpr::Binary: {
707        const MCBinaryExpr *BE = cast<MCBinaryExpr>(Value);
708        AddValueSymbols(BE->getLHS());
709        AddValueSymbols(BE->getRHS());
710        break;
711      }
712
713      case MCExpr::SymbolRef:
714        markUsed(cast<MCSymbolRefExpr>(Value)->getSymbol());
715        break;
716
717      case MCExpr::Unary:
718        AddValueSymbols(cast<MCUnaryExpr>(Value)->getSubExpr());
719        break;
720      }
721    }
722
723  public:
724    typedef StringMap<State>::const_iterator const_iterator;
725
726    const_iterator begin() {
727      return Symbols.begin();
728    }
729
730    const_iterator end() {
731      return Symbols.end();
732    }
733
734    RecordStreamer(MCContext &Context) : MCStreamer(Context) {}
735
736    virtual void EmitInstruction(const MCInst &Inst) {
737      // Scan for values.
738      for (unsigned i = Inst.getNumOperands(); i--; )
739        if (Inst.getOperand(i).isExpr())
740          AddValueSymbols(Inst.getOperand(i).getExpr());
741    }
742    virtual void EmitLabel(MCSymbol *Symbol) {
743      Symbol->setSection(*getCurrentSection());
744      markDefined(*Symbol);
745    }
746    virtual void EmitAssignment(MCSymbol *Symbol, const MCExpr *Value) {
747      // FIXME: should we handle aliases?
748      markDefined(*Symbol);
749    }
750    virtual void EmitSymbolAttribute(MCSymbol *Symbol, MCSymbolAttr Attribute) {
751      if (Attribute == MCSA_Global)
752        markGlobal(*Symbol);
753    }
754    virtual void EmitZerofill(const MCSection *Section, MCSymbol *Symbol,
755                              uint64_t Size , unsigned ByteAlignment) {
756      markDefined(*Symbol);
757    }
758    virtual void EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
759                                  unsigned ByteAlignment) {
760      markDefined(*Symbol);
761    }
762
763    // Noop calls.
764    virtual void ChangeSection(const MCSection *Section) {}
765    virtual void InitSections() {}
766    virtual void EmitAssemblerFlag(MCAssemblerFlag Flag) {}
767    virtual void EmitThumbFunc(MCSymbol *Func) {}
768    virtual void EmitSymbolDesc(MCSymbol *Symbol, unsigned DescValue) {}
769    virtual void EmitWeakReference(MCSymbol *Alias, const MCSymbol *Symbol) {}
770    virtual void BeginCOFFSymbolDef(const MCSymbol *Symbol) {}
771    virtual void EmitCOFFSymbolStorageClass(int StorageClass) {}
772    virtual void EmitCOFFSymbolType(int Type) {}
773    virtual void EndCOFFSymbolDef() {}
774    virtual void EmitELFSize(MCSymbol *Symbol, const MCExpr *Value) {}
775    virtual void EmitLocalCommonSymbol(MCSymbol *Symbol, uint64_t Size,
776                                       unsigned ByteAlignment) {}
777    virtual void EmitTBSSSymbol(const MCSection *Section, MCSymbol *Symbol,
778                                uint64_t Size, unsigned ByteAlignment) {}
779    virtual void EmitBytes(StringRef Data, unsigned AddrSpace) {}
780    virtual void EmitValueImpl(const MCExpr *Value, unsigned Size,
781                               unsigned AddrSpace) {}
782    virtual void EmitULEB128Value(const MCExpr *Value) {}
783    virtual void EmitSLEB128Value(const MCExpr *Value) {}
784    virtual void EmitValueToAlignment(unsigned ByteAlignment, int64_t Value,
785                                      unsigned ValueSize,
786                                      unsigned MaxBytesToEmit) {}
787    virtual void EmitCodeAlignment(unsigned ByteAlignment,
788                                   unsigned MaxBytesToEmit) {}
789    virtual bool EmitValueToOffset(const MCExpr *Offset,
790                                   unsigned char Value ) { return false; }
791    virtual void EmitFileDirective(StringRef Filename) {}
792    virtual void EmitDwarfAdvanceLineAddr(int64_t LineDelta,
793                                          const MCSymbol *LastLabel,
794                                          const MCSymbol *Label,
795                                          unsigned PointerSize) {}
796    virtual void FinishImpl() {}
797  };
798} // end anonymous namespace
799
800/// addAsmGlobalSymbols - Add global symbols from module-level ASM to the
801/// defined or undefined lists.
802bool LTOModule::addAsmGlobalSymbols(std::string &errMsg) {
803  const std::string &inlineAsm = _module->getModuleInlineAsm();
804  if (inlineAsm.empty())
805    return false;
806
807  OwningPtr<RecordStreamer> Streamer(new RecordStreamer(_context));
808  MemoryBuffer *Buffer = MemoryBuffer::getMemBuffer(inlineAsm);
809  SourceMgr SrcMgr;
810  SrcMgr.AddNewSourceBuffer(Buffer, SMLoc());
811  OwningPtr<MCAsmParser> Parser(createMCAsmParser(SrcMgr,
812                                                  _context, *Streamer,
813                                                  *_target->getMCAsmInfo()));
814  const Target &T = _target->getTarget();
815  OwningPtr<MCSubtargetInfo>
816    STI(T.createMCSubtargetInfo(_target->getTargetTriple(),
817                                _target->getTargetCPU(),
818                                _target->getTargetFeatureString()));
819  OwningPtr<MCTargetAsmParser> TAP(T.createMCAsmParser(*STI, *Parser.get()));
820  if (!TAP) {
821    errMsg = "target " + std::string(T.getName()) +
822      " does not define AsmParser.";
823    return true;
824  }
825
826  Parser->setTargetParser(*TAP);
827  if (Parser->Run(false))
828    return true;
829
830  for (RecordStreamer::const_iterator i = Streamer->begin(),
831         e = Streamer->end(); i != e; ++i) {
832    StringRef Key = i->first();
833    RecordStreamer::State Value = i->second;
834    if (Value == RecordStreamer::DefinedGlobal)
835      addAsmGlobalSymbol(Key.data(), LTO_SYMBOL_SCOPE_DEFAULT);
836    else if (Value == RecordStreamer::Defined)
837      addAsmGlobalSymbol(Key.data(), LTO_SYMBOL_SCOPE_INTERNAL);
838    else if (Value == RecordStreamer::Global ||
839             Value == RecordStreamer::Used)
840      addAsmGlobalSymbolUndef(Key.data());
841  }
842
843  return false;
844}
845
846/// isDeclaration - Return 'true' if the global value is a declaration.
847static bool isDeclaration(const GlobalValue &V) {
848  if (V.hasAvailableExternallyLinkage())
849    return true;
850
851  if (V.isMaterializable())
852    return false;
853
854  return V.isDeclaration();
855}
856
857/// parseSymbols - Parse the symbols from the module and model-level ASM and add
858/// them to either the defined or undefined lists.
859bool LTOModule::parseSymbols(std::string &errMsg) {
860  // add functions
861  for (Module::iterator f = _module->begin(), e = _module->end(); f != e; ++f) {
862    if (isDeclaration(*f))
863      addPotentialUndefinedSymbol(f, true);
864    else
865      addDefinedFunctionSymbol(f);
866  }
867
868  // add data
869  for (Module::global_iterator v = _module->global_begin(),
870         e = _module->global_end(); v !=  e; ++v) {
871    if (isDeclaration(*v))
872      addPotentialUndefinedSymbol(v, false);
873    else
874      addDefinedDataSymbol(v);
875  }
876
877  // add asm globals
878  if (addAsmGlobalSymbols(errMsg))
879    return true;
880
881  // add aliases
882  for (Module::alias_iterator a = _module->alias_begin(),
883         e = _module->alias_end(); a != e; ++a) {
884    if (isDeclaration(*a->getAliasedGlobal()))
885      // Is an alias to a declaration.
886      addPotentialUndefinedSymbol(a, false);
887    else
888      addDefinedDataSymbol(a);
889  }
890
891  // make symbols for all undefines
892  for (StringMap<NameAndAttributes>::iterator u =_undefines.begin(),
893         e = _undefines.end(); u != e; ++u) {
894    // If this symbol also has a definition, then don't make an undefine because
895    // it is a tentative definition.
896    if (_defines.count(u->getKey())) continue;
897    NameAndAttributes info = u->getValue();
898    _symbols.push_back(info);
899  }
900
901  return false;
902}
903