1//===-- Function.cpp - Implement the Global object classes ----------------===//
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 Function class for the VMCore library.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Module.h"
15#include "llvm/DerivedTypes.h"
16#include "llvm/IntrinsicInst.h"
17#include "llvm/LLVMContext.h"
18#include "llvm/CodeGen/ValueTypes.h"
19#include "llvm/Support/CallSite.h"
20#include "llvm/Support/InstIterator.h"
21#include "llvm/Support/LeakDetector.h"
22#include "llvm/Support/ManagedStatic.h"
23#include "llvm/Support/StringPool.h"
24#include "llvm/Support/RWMutex.h"
25#include "llvm/Support/Threading.h"
26#include "SymbolTableListTraitsImpl.h"
27#include "llvm/ADT/DenseMap.h"
28#include "llvm/ADT/STLExtras.h"
29#include "llvm/ADT/StringExtras.h"
30using namespace llvm;
31
32// Explicit instantiations of SymbolTableListTraits since some of the methods
33// are not in the public header file...
34template class llvm::SymbolTableListTraits<Argument, Function>;
35template class llvm::SymbolTableListTraits<BasicBlock, Function>;
36
37//===----------------------------------------------------------------------===//
38// Argument Implementation
39//===----------------------------------------------------------------------===//
40
41void Argument::anchor() { }
42
43Argument::Argument(Type *Ty, const Twine &Name, Function *Par)
44  : Value(Ty, Value::ArgumentVal) {
45  Parent = 0;
46
47  // Make sure that we get added to a function
48  LeakDetector::addGarbageObject(this);
49
50  if (Par)
51    Par->getArgumentList().push_back(this);
52  setName(Name);
53}
54
55void Argument::setParent(Function *parent) {
56  if (getParent())
57    LeakDetector::addGarbageObject(this);
58  Parent = parent;
59  if (getParent())
60    LeakDetector::removeGarbageObject(this);
61}
62
63/// getArgNo - Return the index of this formal argument in its containing
64/// function.  For example in "void foo(int a, float b)" a is 0 and b is 1.
65unsigned Argument::getArgNo() const {
66  const Function *F = getParent();
67  assert(F && "Argument is not in a function");
68
69  Function::const_arg_iterator AI = F->arg_begin();
70  unsigned ArgIdx = 0;
71  for (; &*AI != this; ++AI)
72    ++ArgIdx;
73
74  return ArgIdx;
75}
76
77/// hasByValAttr - Return true if this argument has the byval attribute on it
78/// in its containing function.
79bool Argument::hasByValAttr() const {
80  if (!getType()->isPointerTy()) return false;
81  return getParent()->getParamAttributes(getArgNo()+1).hasByValAttr();
82}
83
84unsigned Argument::getParamAlignment() const {
85  assert(getType()->isPointerTy() && "Only pointers have alignments");
86  return getParent()->getParamAlignment(getArgNo()+1);
87
88}
89
90/// hasNestAttr - Return true if this argument has the nest attribute on
91/// it in its containing function.
92bool Argument::hasNestAttr() const {
93  if (!getType()->isPointerTy()) return false;
94  return getParent()->getParamAttributes(getArgNo()+1).hasNestAttr();
95}
96
97/// hasNoAliasAttr - Return true if this argument has the noalias attribute on
98/// it in its containing function.
99bool Argument::hasNoAliasAttr() const {
100  if (!getType()->isPointerTy()) return false;
101  return getParent()->getParamAttributes(getArgNo()+1).hasNoAliasAttr();
102}
103
104/// hasNoCaptureAttr - Return true if this argument has the nocapture attribute
105/// on it in its containing function.
106bool Argument::hasNoCaptureAttr() const {
107  if (!getType()->isPointerTy()) return false;
108  return getParent()->getParamAttributes(getArgNo()+1).hasNoCaptureAttr();
109}
110
111/// hasSRetAttr - Return true if this argument has the sret attribute on
112/// it in its containing function.
113bool Argument::hasStructRetAttr() const {
114  if (!getType()->isPointerTy()) return false;
115  if (this != getParent()->arg_begin())
116    return false; // StructRet param must be first param
117  return getParent()->getParamAttributes(1).hasStructRetAttr();
118}
119
120/// addAttr - Add a Attribute to an argument
121void Argument::addAttr(Attributes attr) {
122  getParent()->addAttribute(getArgNo() + 1, attr);
123}
124
125/// removeAttr - Remove a Attribute from an argument
126void Argument::removeAttr(Attributes attr) {
127  getParent()->removeAttribute(getArgNo() + 1, attr);
128}
129
130
131//===----------------------------------------------------------------------===//
132// Helper Methods in Function
133//===----------------------------------------------------------------------===//
134
135LLVMContext &Function::getContext() const {
136  return getType()->getContext();
137}
138
139FunctionType *Function::getFunctionType() const {
140  return cast<FunctionType>(getType()->getElementType());
141}
142
143bool Function::isVarArg() const {
144  return getFunctionType()->isVarArg();
145}
146
147Type *Function::getReturnType() const {
148  return getFunctionType()->getReturnType();
149}
150
151void Function::removeFromParent() {
152  getParent()->getFunctionList().remove(this);
153}
154
155void Function::eraseFromParent() {
156  getParent()->getFunctionList().erase(this);
157}
158
159//===----------------------------------------------------------------------===//
160// Function Implementation
161//===----------------------------------------------------------------------===//
162
163Function::Function(FunctionType *Ty, LinkageTypes Linkage,
164                   const Twine &name, Module *ParentModule)
165  : GlobalValue(PointerType::getUnqual(Ty),
166                Value::FunctionVal, 0, 0, Linkage, name) {
167  assert(FunctionType::isValidReturnType(getReturnType()) &&
168         "invalid return type");
169  SymTab = new ValueSymbolTable();
170
171  // If the function has arguments, mark them as lazily built.
172  if (Ty->getNumParams())
173    setValueSubclassData(1);   // Set the "has lazy arguments" bit.
174
175  // Make sure that we get added to a function
176  LeakDetector::addGarbageObject(this);
177
178  if (ParentModule)
179    ParentModule->getFunctionList().push_back(this);
180
181  // Ensure intrinsics have the right parameter attributes.
182  if (unsigned IID = getIntrinsicID())
183    setAttributes(Intrinsic::getAttributes(Intrinsic::ID(IID)));
184
185}
186
187Function::~Function() {
188  dropAllReferences();    // After this it is safe to delete instructions.
189
190  // Delete all of the method arguments and unlink from symbol table...
191  ArgumentList.clear();
192  delete SymTab;
193
194  // Remove the function from the on-the-side GC table.
195  clearGC();
196}
197
198void Function::BuildLazyArguments() const {
199  // Create the arguments vector, all arguments start out unnamed.
200  FunctionType *FT = getFunctionType();
201  for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
202    assert(!FT->getParamType(i)->isVoidTy() &&
203           "Cannot have void typed arguments!");
204    ArgumentList.push_back(new Argument(FT->getParamType(i)));
205  }
206
207  // Clear the lazy arguments bit.
208  unsigned SDC = getSubclassDataFromValue();
209  const_cast<Function*>(this)->setValueSubclassData(SDC &= ~1);
210}
211
212size_t Function::arg_size() const {
213  return getFunctionType()->getNumParams();
214}
215bool Function::arg_empty() const {
216  return getFunctionType()->getNumParams() == 0;
217}
218
219void Function::setParent(Module *parent) {
220  if (getParent())
221    LeakDetector::addGarbageObject(this);
222  Parent = parent;
223  if (getParent())
224    LeakDetector::removeGarbageObject(this);
225}
226
227// dropAllReferences() - This function causes all the subinstructions to "let
228// go" of all references that they are maintaining.  This allows one to
229// 'delete' a whole class at a time, even though there may be circular
230// references... first all references are dropped, and all use counts go to
231// zero.  Then everything is deleted for real.  Note that no operations are
232// valid on an object that has "dropped all references", except operator
233// delete.
234//
235void Function::dropAllReferences() {
236  for (iterator I = begin(), E = end(); I != E; ++I)
237    I->dropAllReferences();
238
239  // Delete all basic blocks. They are now unused, except possibly by
240  // blockaddresses, but BasicBlock's destructor takes care of those.
241  while (!BasicBlocks.empty())
242    BasicBlocks.begin()->eraseFromParent();
243}
244
245void Function::addAttribute(unsigned i, Attributes attr) {
246  AttrListPtr PAL = getAttributes();
247  PAL = PAL.addAttr(i, attr);
248  setAttributes(PAL);
249}
250
251void Function::removeAttribute(unsigned i, Attributes attr) {
252  AttrListPtr PAL = getAttributes();
253  PAL = PAL.removeAttr(i, attr);
254  setAttributes(PAL);
255}
256
257// Maintain the GC name for each function in an on-the-side table. This saves
258// allocating an additional word in Function for programs which do not use GC
259// (i.e., most programs) at the cost of increased overhead for clients which do
260// use GC.
261static DenseMap<const Function*,PooledStringPtr> *GCNames;
262static StringPool *GCNamePool;
263static ManagedStatic<sys::SmartRWMutex<true> > GCLock;
264
265bool Function::hasGC() const {
266  sys::SmartScopedReader<true> Reader(*GCLock);
267  return GCNames && GCNames->count(this);
268}
269
270const char *Function::getGC() const {
271  assert(hasGC() && "Function has no collector");
272  sys::SmartScopedReader<true> Reader(*GCLock);
273  return *(*GCNames)[this];
274}
275
276void Function::setGC(const char *Str) {
277  sys::SmartScopedWriter<true> Writer(*GCLock);
278  if (!GCNamePool)
279    GCNamePool = new StringPool();
280  if (!GCNames)
281    GCNames = new DenseMap<const Function*,PooledStringPtr>();
282  (*GCNames)[this] = GCNamePool->intern(Str);
283}
284
285void Function::clearGC() {
286  sys::SmartScopedWriter<true> Writer(*GCLock);
287  if (GCNames) {
288    GCNames->erase(this);
289    if (GCNames->empty()) {
290      delete GCNames;
291      GCNames = 0;
292      if (GCNamePool->empty()) {
293        delete GCNamePool;
294        GCNamePool = 0;
295      }
296    }
297  }
298}
299
300/// copyAttributesFrom - copy all additional attributes (those not needed to
301/// create a Function) from the Function Src to this one.
302void Function::copyAttributesFrom(const GlobalValue *Src) {
303  assert(isa<Function>(Src) && "Expected a Function!");
304  GlobalValue::copyAttributesFrom(Src);
305  const Function *SrcF = cast<Function>(Src);
306  setCallingConv(SrcF->getCallingConv());
307  setAttributes(SrcF->getAttributes());
308  if (SrcF->hasGC())
309    setGC(SrcF->getGC());
310  else
311    clearGC();
312}
313
314/// getIntrinsicID - This method returns the ID number of the specified
315/// function, or Intrinsic::not_intrinsic if the function is not an
316/// intrinsic, or if the pointer is null.  This value is always defined to be
317/// zero to allow easy checking for whether a function is intrinsic or not.  The
318/// particular intrinsic functions which correspond to this value are defined in
319/// llvm/Intrinsics.h.
320///
321unsigned Function::getIntrinsicID() const {
322  const ValueName *ValName = this->getValueName();
323  if (!ValName)
324    return 0;
325  unsigned Len = ValName->getKeyLength();
326  const char *Name = ValName->getKeyData();
327
328  if (Len < 5 || Name[4] != '.' || Name[0] != 'l' || Name[1] != 'l'
329      || Name[2] != 'v' || Name[3] != 'm')
330    return 0;  // All intrinsics start with 'llvm.'
331
332#define GET_FUNCTION_RECOGNIZER
333#include "llvm/Intrinsics.gen"
334#undef GET_FUNCTION_RECOGNIZER
335  return 0;
336}
337
338std::string Intrinsic::getName(ID id, ArrayRef<Type*> Tys) {
339  assert(id < num_intrinsics && "Invalid intrinsic ID!");
340  static const char * const Table[] = {
341    "not_intrinsic",
342#define GET_INTRINSIC_NAME_TABLE
343#include "llvm/Intrinsics.gen"
344#undef GET_INTRINSIC_NAME_TABLE
345  };
346  if (Tys.empty())
347    return Table[id];
348  std::string Result(Table[id]);
349  for (unsigned i = 0; i < Tys.size(); ++i) {
350    if (PointerType* PTyp = dyn_cast<PointerType>(Tys[i])) {
351      Result += ".p" + llvm::utostr(PTyp->getAddressSpace()) +
352                EVT::getEVT(PTyp->getElementType()).getEVTString();
353    }
354    else if (Tys[i])
355      Result += "." + EVT::getEVT(Tys[i]).getEVTString();
356  }
357  return Result;
358}
359
360
361/// IIT_Info - These are enumerators that describe the entries returned by the
362/// getIntrinsicInfoTableEntries function.
363///
364/// NOTE: This must be kept in synch with the copy in TblGen/IntrinsicEmitter!
365enum IIT_Info {
366  // Common values should be encoded with 0-15.
367  IIT_Done = 0,
368  IIT_I1   = 1,
369  IIT_I8   = 2,
370  IIT_I16  = 3,
371  IIT_I32  = 4,
372  IIT_I64  = 5,
373  IIT_F32  = 6,
374  IIT_F64  = 7,
375  IIT_V2   = 8,
376  IIT_V4   = 9,
377  IIT_V8   = 10,
378  IIT_V16  = 11,
379  IIT_V32  = 12,
380  IIT_MMX  = 13,
381  IIT_PTR  = 14,
382  IIT_ARG  = 15,
383
384  // Values from 16+ are only encodable with the inefficient encoding.
385  IIT_METADATA = 16,
386  IIT_EMPTYSTRUCT = 17,
387  IIT_STRUCT2 = 18,
388  IIT_STRUCT3 = 19,
389  IIT_STRUCT4 = 20,
390  IIT_STRUCT5 = 21,
391  IIT_EXTEND_VEC_ARG = 22,
392  IIT_TRUNC_VEC_ARG = 23,
393  IIT_ANYPTR = 24
394};
395
396
397static void DecodeIITType(unsigned &NextElt, ArrayRef<unsigned char> Infos,
398                      SmallVectorImpl<Intrinsic::IITDescriptor> &OutputTable) {
399  IIT_Info Info = IIT_Info(Infos[NextElt++]);
400  unsigned StructElts = 2;
401  using namespace Intrinsic;
402
403  switch (Info) {
404  case IIT_Done:
405    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Void, 0));
406    return;
407  case IIT_MMX:
408    OutputTable.push_back(IITDescriptor::get(IITDescriptor::MMX, 0));
409    return;
410  case IIT_METADATA:
411    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Metadata, 0));
412    return;
413  case IIT_F32:
414    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Float, 0));
415    return;
416  case IIT_F64:
417    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Double, 0));
418    return;
419  case IIT_I1:
420    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 1));
421    return;
422  case IIT_I8:
423    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 8));
424    return;
425  case IIT_I16:
426    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer,16));
427    return;
428  case IIT_I32:
429    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 32));
430    return;
431  case IIT_I64:
432    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 64));
433    return;
434  case IIT_V2:
435    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 2));
436    DecodeIITType(NextElt, Infos, OutputTable);
437    return;
438  case IIT_V4:
439    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 4));
440    DecodeIITType(NextElt, Infos, OutputTable);
441    return;
442  case IIT_V8:
443    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 8));
444    DecodeIITType(NextElt, Infos, OutputTable);
445    return;
446  case IIT_V16:
447    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 16));
448    DecodeIITType(NextElt, Infos, OutputTable);
449    return;
450  case IIT_V32:
451    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 32));
452    DecodeIITType(NextElt, Infos, OutputTable);
453    return;
454  case IIT_PTR:
455    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Pointer, 0));
456    DecodeIITType(NextElt, Infos, OutputTable);
457    return;
458  case IIT_ANYPTR: {  // [ANYPTR addrspace, subtype]
459    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Pointer,
460                                             Infos[NextElt++]));
461    DecodeIITType(NextElt, Infos, OutputTable);
462    return;
463  }
464  case IIT_ARG: {
465    unsigned ArgInfo = (NextElt == Infos.size() ? 0 : Infos[NextElt++]);
466    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Argument, ArgInfo));
467    return;
468  }
469  case IIT_EXTEND_VEC_ARG: {
470    unsigned ArgInfo = (NextElt == Infos.size() ? 0 : Infos[NextElt++]);
471    OutputTable.push_back(IITDescriptor::get(IITDescriptor::ExtendVecArgument,
472                                             ArgInfo));
473    return;
474  }
475  case IIT_TRUNC_VEC_ARG: {
476    unsigned ArgInfo = (NextElt == Infos.size() ? 0 : Infos[NextElt++]);
477    OutputTable.push_back(IITDescriptor::get(IITDescriptor::TruncVecArgument,
478                                             ArgInfo));
479    return;
480  }
481  case IIT_EMPTYSTRUCT:
482    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Struct, 0));
483    return;
484  case IIT_STRUCT5: ++StructElts; // FALL THROUGH.
485  case IIT_STRUCT4: ++StructElts; // FALL THROUGH.
486  case IIT_STRUCT3: ++StructElts; // FALL THROUGH.
487  case IIT_STRUCT2: {
488    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Struct,StructElts));
489
490    for (unsigned i = 0; i != StructElts; ++i)
491      DecodeIITType(NextElt, Infos, OutputTable);
492    return;
493  }
494  }
495  llvm_unreachable("unhandled");
496}
497
498
499#define GET_INTRINSIC_GENERATOR_GLOBAL
500#include "llvm/Intrinsics.gen"
501#undef GET_INTRINSIC_GENERATOR_GLOBAL
502
503void Intrinsic::getIntrinsicInfoTableEntries(ID id,
504                                             SmallVectorImpl<IITDescriptor> &T){
505  // Check to see if the intrinsic's type was expressible by the table.
506  unsigned TableVal = IIT_Table[id-1];
507
508  // Decode the TableVal into an array of IITValues.
509  SmallVector<unsigned char, 8> IITValues;
510  ArrayRef<unsigned char> IITEntries;
511  unsigned NextElt = 0;
512  if ((TableVal >> 31) != 0) {
513    // This is an offset into the IIT_LongEncodingTable.
514    IITEntries = IIT_LongEncodingTable;
515
516    // Strip sentinel bit.
517    NextElt = (TableVal << 1) >> 1;
518  } else {
519    // Decode the TableVal into an array of IITValues.  If the entry was encoded
520    // into a single word in the table itself, decode it now.
521    do {
522      IITValues.push_back(TableVal & 0xF);
523      TableVal >>= 4;
524    } while (TableVal);
525
526    IITEntries = IITValues;
527    NextElt = 0;
528  }
529
530  // Okay, decode the table into the output vector of IITDescriptors.
531  DecodeIITType(NextElt, IITEntries, T);
532  while (NextElt != IITEntries.size() && IITEntries[NextElt] != 0)
533    DecodeIITType(NextElt, IITEntries, T);
534}
535
536
537static Type *DecodeFixedType(ArrayRef<Intrinsic::IITDescriptor> &Infos,
538                             ArrayRef<Type*> Tys, LLVMContext &Context) {
539  using namespace Intrinsic;
540  IITDescriptor D = Infos.front();
541  Infos = Infos.slice(1);
542
543  switch (D.Kind) {
544  case IITDescriptor::Void: return Type::getVoidTy(Context);
545  case IITDescriptor::MMX: return Type::getX86_MMXTy(Context);
546  case IITDescriptor::Metadata: return Type::getMetadataTy(Context);
547  case IITDescriptor::Float: return Type::getFloatTy(Context);
548  case IITDescriptor::Double: return Type::getDoubleTy(Context);
549
550  case IITDescriptor::Integer:
551    return IntegerType::get(Context, D.Integer_Width);
552  case IITDescriptor::Vector:
553    return VectorType::get(DecodeFixedType(Infos, Tys, Context),D.Vector_Width);
554  case IITDescriptor::Pointer:
555    return PointerType::get(DecodeFixedType(Infos, Tys, Context),
556                            D.Pointer_AddressSpace);
557  case IITDescriptor::Struct: {
558    Type *Elts[5];
559    assert(D.Struct_NumElements <= 5 && "Can't handle this yet");
560    for (unsigned i = 0, e = D.Struct_NumElements; i != e; ++i)
561      Elts[i] = DecodeFixedType(Infos, Tys, Context);
562    return StructType::get(Context, ArrayRef<Type*>(Elts,D.Struct_NumElements));
563  }
564
565  case IITDescriptor::Argument:
566    return Tys[D.getArgumentNumber()];
567  case IITDescriptor::ExtendVecArgument:
568    return VectorType::getExtendedElementVectorType(cast<VectorType>(
569                                                  Tys[D.getArgumentNumber()]));
570
571  case IITDescriptor::TruncVecArgument:
572    return VectorType::getTruncatedElementVectorType(cast<VectorType>(
573                                                  Tys[D.getArgumentNumber()]));
574  }
575  llvm_unreachable("unhandled");
576}
577
578
579
580FunctionType *Intrinsic::getType(LLVMContext &Context,
581                                 ID id, ArrayRef<Type*> Tys) {
582  SmallVector<IITDescriptor, 8> Table;
583  getIntrinsicInfoTableEntries(id, Table);
584
585  ArrayRef<IITDescriptor> TableRef = Table;
586  Type *ResultTy = DecodeFixedType(TableRef, Tys, Context);
587
588  SmallVector<Type*, 8> ArgTys;
589  while (!TableRef.empty())
590    ArgTys.push_back(DecodeFixedType(TableRef, Tys, Context));
591
592  return FunctionType::get(ResultTy, ArgTys, false);
593}
594
595bool Intrinsic::isOverloaded(ID id) {
596#define GET_INTRINSIC_OVERLOAD_TABLE
597#include "llvm/Intrinsics.gen"
598#undef GET_INTRINSIC_OVERLOAD_TABLE
599}
600
601/// This defines the "Intrinsic::getAttributes(ID id)" method.
602#define GET_INTRINSIC_ATTRIBUTES
603#include "llvm/Intrinsics.gen"
604#undef GET_INTRINSIC_ATTRIBUTES
605
606Function *Intrinsic::getDeclaration(Module *M, ID id, ArrayRef<Type*> Tys) {
607  // There can never be multiple globals with the same name of different types,
608  // because intrinsics must be a specific type.
609  return
610    cast<Function>(M->getOrInsertFunction(getName(id, Tys),
611                                          getType(M->getContext(), id, Tys)));
612}
613
614// This defines the "Intrinsic::getIntrinsicForGCCBuiltin()" method.
615#define GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
616#include "llvm/Intrinsics.gen"
617#undef GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
618
619/// hasAddressTaken - returns true if there are any uses of this function
620/// other than direct calls or invokes to it.
621bool Function::hasAddressTaken(const User* *PutOffender) const {
622  for (Value::const_use_iterator I = use_begin(), E = use_end(); I != E; ++I) {
623    const User *U = *I;
624    if (isa<BlockAddress>(U))
625      continue;
626    if (!isa<CallInst>(U) && !isa<InvokeInst>(U))
627      return PutOffender ? (*PutOffender = U, true) : true;
628    ImmutableCallSite CS(cast<Instruction>(U));
629    if (!CS.isCallee(I))
630      return PutOffender ? (*PutOffender = U, true) : true;
631  }
632  return false;
633}
634
635bool Function::isDefTriviallyDead() const {
636  // Check the linkage
637  if (!hasLinkOnceLinkage() && !hasLocalLinkage() &&
638      !hasAvailableExternallyLinkage())
639    return false;
640
641  // Check if the function is used by anything other than a blockaddress.
642  for (Value::const_use_iterator I = use_begin(), E = use_end(); I != E; ++I)
643    if (!isa<BlockAddress>(*I))
644      return false;
645
646  return true;
647}
648
649/// callsFunctionThatReturnsTwice - Return true if the function has a call to
650/// setjmp or other function that gcc recognizes as "returning twice".
651bool Function::callsFunctionThatReturnsTwice() const {
652  for (const_inst_iterator
653         I = inst_begin(this), E = inst_end(this); I != E; ++I) {
654    const CallInst* callInst = dyn_cast<CallInst>(&*I);
655    if (!callInst)
656      continue;
657    if (callInst->canReturnTwice())
658      return true;
659  }
660
661  return false;
662}
663
664