Function.cpp revision 351ba145a7db32b457f118ecc4d873765ac2a16b 
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 IR library.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/IR/Function.h"
15#include "SymbolTableListTraitsImpl.h"
16#include "llvm/ADT/DenseMap.h"
17#include "llvm/ADT/STLExtras.h"
18#include "llvm/ADT/StringExtras.h"
19#include "llvm/CodeGen/ValueTypes.h"
20#include "llvm/IR/DerivedTypes.h"
21#include "llvm/IR/IntrinsicInst.h"
22#include "llvm/IR/LLVMContext.h"
23#include "llvm/IR/Module.h"
24#include "llvm/Support/CallSite.h"
25#include "llvm/Support/InstIterator.h"
26#include "llvm/Support/LeakDetector.h"
27#include "llvm/Support/ManagedStatic.h"
28#include "llvm/Support/RWMutex.h"
29#include "llvm/Support/StringPool.h"
30#include "llvm/Support/Threading.h"
31using namespace llvm;
32
33// Explicit instantiations of SymbolTableListTraits since some of the methods
34// are not in the public header file...
35template class llvm::SymbolTableListTraits<Argument, Function>;
36template class llvm::SymbolTableListTraits<BasicBlock, Function>;
37
38//===----------------------------------------------------------------------===//
39// Argument Implementation
40//===----------------------------------------------------------------------===//
41
42void Argument::anchor() { }
43
44Argument::Argument(Type *Ty, const Twine &Name, Function *Par)
45  : Value(Ty, Value::ArgumentVal) {
46  Parent = 0;
47
48  // Make sure that we get added to a function
49  LeakDetector::addGarbageObject(this);
50
51  if (Par)
52    Par->getArgumentList().push_back(this);
53  setName(Name);
54}
55
56void Argument::setParent(Function *parent) {
57  if (getParent())
58    LeakDetector::addGarbageObject(this);
59  Parent = parent;
60  if (getParent())
61    LeakDetector::removeGarbageObject(this);
62}
63
64/// getArgNo - Return the index of this formal argument in its containing
65/// function.  For example in "void foo(int a, float b)" a is 0 and b is 1.
66unsigned Argument::getArgNo() const {
67  const Function *F = getParent();
68  assert(F && "Argument is not in a function");
69
70  Function::const_arg_iterator AI = F->arg_begin();
71  unsigned ArgIdx = 0;
72  for (; &*AI != this; ++AI)
73    ++ArgIdx;
74
75  return ArgIdx;
76}
77
78/// hasByValAttr - Return true if this argument has the byval attribute on it
79/// in its containing function.
80bool Argument::hasByValAttr() const {
81  if (!getType()->isPointerTy()) return false;
82  return getParent()->getAttributes().
83    hasAttribute(getArgNo()+1, Attribute::ByVal);
84}
85
86unsigned Argument::getParamAlignment() const {
87  assert(getType()->isPointerTy() && "Only pointers have alignments");
88  return getParent()->getParamAlignment(getArgNo()+1);
89
90}
91
92/// hasNestAttr - Return true if this argument has the nest attribute on
93/// it in its containing function.
94bool Argument::hasNestAttr() const {
95  if (!getType()->isPointerTy()) return false;
96  return getParent()->getAttributes().
97    hasAttribute(getArgNo()+1, Attribute::Nest);
98}
99
100/// hasNoAliasAttr - Return true if this argument has the noalias attribute on
101/// it in its containing function.
102bool Argument::hasNoAliasAttr() const {
103  if (!getType()->isPointerTy()) return false;
104  return getParent()->getAttributes().
105    hasAttribute(getArgNo()+1, Attribute::NoAlias);
106}
107
108/// hasNoCaptureAttr - Return true if this argument has the nocapture attribute
109/// on it in its containing function.
110bool Argument::hasNoCaptureAttr() const {
111  if (!getType()->isPointerTy()) return false;
112  return getParent()->getAttributes().
113    hasAttribute(getArgNo()+1, Attribute::NoCapture);
114}
115
116/// hasSRetAttr - Return true if this argument has the sret attribute on
117/// it in its containing function.
118bool Argument::hasStructRetAttr() const {
119  if (!getType()->isPointerTy()) return false;
120  if (this != getParent()->arg_begin())
121    return false; // StructRet param must be first param
122  return getParent()->getAttributes().
123    hasAttribute(1, Attribute::StructRet);
124}
125
126/// addAttr - Add a Attribute to an argument
127void Argument::addAttr(Attribute attr) {
128  getParent()->addAttribute(getArgNo() + 1, attr);
129}
130
131/// removeAttr - Remove a Attribute from an argument
132void Argument::removeAttr(Attribute attr) {
133  getParent()->removeAttribute(getArgNo() + 1, attr);
134}
135
136
137//===----------------------------------------------------------------------===//
138// Helper Methods in Function
139//===----------------------------------------------------------------------===//
140
141LLVMContext &Function::getContext() const {
142  return getType()->getContext();
143}
144
145FunctionType *Function::getFunctionType() const {
146  return cast<FunctionType>(getType()->getElementType());
147}
148
149bool Function::isVarArg() const {
150  return getFunctionType()->isVarArg();
151}
152
153Type *Function::getReturnType() const {
154  return getFunctionType()->getReturnType();
155}
156
157void Function::removeFromParent() {
158  getParent()->getFunctionList().remove(this);
159}
160
161void Function::eraseFromParent() {
162  getParent()->getFunctionList().erase(this);
163}
164
165//===----------------------------------------------------------------------===//
166// Function Implementation
167//===----------------------------------------------------------------------===//
168
169Function::Function(FunctionType *Ty, LinkageTypes Linkage,
170                   const Twine &name, Module *ParentModule)
171  : GlobalValue(PointerType::getUnqual(Ty),
172                Value::FunctionVal, 0, 0, Linkage, name) {
173  assert(FunctionType::isValidReturnType(getReturnType()) &&
174         "invalid return type");
175  SymTab = new ValueSymbolTable();
176
177  // If the function has arguments, mark them as lazily built.
178  if (Ty->getNumParams())
179    setValueSubclassData(1);   // Set the "has lazy arguments" bit.
180
181  // Make sure that we get added to a function
182  LeakDetector::addGarbageObject(this);
183
184  if (ParentModule)
185    ParentModule->getFunctionList().push_back(this);
186
187  // Ensure intrinsics have the right parameter attributes.
188  if (unsigned IID = getIntrinsicID())
189    setAttributes(Intrinsic::getAttributes(getContext(), Intrinsic::ID(IID)));
190
191}
192
193Function::~Function() {
194  dropAllReferences();    // After this it is safe to delete instructions.
195
196  // Delete all of the method arguments and unlink from symbol table...
197  ArgumentList.clear();
198  delete SymTab;
199
200  // Remove the function from the on-the-side GC table.
201  clearGC();
202}
203
204void Function::BuildLazyArguments() const {
205  // Create the arguments vector, all arguments start out unnamed.
206  FunctionType *FT = getFunctionType();
207  for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
208    assert(!FT->getParamType(i)->isVoidTy() &&
209           "Cannot have void typed arguments!");
210    ArgumentList.push_back(new Argument(FT->getParamType(i)));
211  }
212
213  // Clear the lazy arguments bit.
214  unsigned SDC = getSubclassDataFromValue();
215  const_cast<Function*>(this)->setValueSubclassData(SDC &= ~1);
216}
217
218size_t Function::arg_size() const {
219  return getFunctionType()->getNumParams();
220}
221bool Function::arg_empty() const {
222  return getFunctionType()->getNumParams() == 0;
223}
224
225void Function::setParent(Module *parent) {
226  if (getParent())
227    LeakDetector::addGarbageObject(this);
228  Parent = parent;
229  if (getParent())
230    LeakDetector::removeGarbageObject(this);
231}
232
233// dropAllReferences() - This function causes all the subinstructions to "let
234// go" of all references that they are maintaining.  This allows one to
235// 'delete' a whole class at a time, even though there may be circular
236// references... first all references are dropped, and all use counts go to
237// zero.  Then everything is deleted for real.  Note that no operations are
238// valid on an object that has "dropped all references", except operator
239// delete.
240//
241void Function::dropAllReferences() {
242  for (iterator I = begin(), E = end(); I != E; ++I)
243    I->dropAllReferences();
244
245  // Delete all basic blocks. They are now unused, except possibly by
246  // blockaddresses, but BasicBlock's destructor takes care of those.
247  while (!BasicBlocks.empty())
248    BasicBlocks.begin()->eraseFromParent();
249}
250
251void Function::addAttribute(unsigned i, Attribute attr) {
252  AttributeSet PAL = getAttributes();
253  PAL = PAL.addAttr(getContext(), i, attr);
254  setAttributes(PAL);
255}
256
257void Function::removeAttribute(unsigned i, Attribute attr) {
258  AttributeSet PAL = getAttributes();
259  PAL = PAL.removeAttr(getContext(), i, attr);
260  setAttributes(PAL);
261}
262
263// Maintain the GC name for each function in an on-the-side table. This saves
264// allocating an additional word in Function for programs which do not use GC
265// (i.e., most programs) at the cost of increased overhead for clients which do
266// use GC.
267static DenseMap<const Function*,PooledStringPtr> *GCNames;
268static StringPool *GCNamePool;
269static ManagedStatic<sys::SmartRWMutex<true> > GCLock;
270
271bool Function::hasGC() const {
272  sys::SmartScopedReader<true> Reader(*GCLock);
273  return GCNames && GCNames->count(this);
274}
275
276const char *Function::getGC() const {
277  assert(hasGC() && "Function has no collector");
278  sys::SmartScopedReader<true> Reader(*GCLock);
279  return *(*GCNames)[this];
280}
281
282void Function::setGC(const char *Str) {
283  sys::SmartScopedWriter<true> Writer(*GCLock);
284  if (!GCNamePool)
285    GCNamePool = new StringPool();
286  if (!GCNames)
287    GCNames = new DenseMap<const Function*,PooledStringPtr>();
288  (*GCNames)[this] = GCNamePool->intern(Str);
289}
290
291void Function::clearGC() {
292  sys::SmartScopedWriter<true> Writer(*GCLock);
293  if (GCNames) {
294    GCNames->erase(this);
295    if (GCNames->empty()) {
296      delete GCNames;
297      GCNames = 0;
298      if (GCNamePool->empty()) {
299        delete GCNamePool;
300        GCNamePool = 0;
301      }
302    }
303  }
304}
305
306/// copyAttributesFrom - copy all additional attributes (those not needed to
307/// create a Function) from the Function Src to this one.
308void Function::copyAttributesFrom(const GlobalValue *Src) {
309  assert(isa<Function>(Src) && "Expected a Function!");
310  GlobalValue::copyAttributesFrom(Src);
311  const Function *SrcF = cast<Function>(Src);
312  setCallingConv(SrcF->getCallingConv());
313  setAttributes(SrcF->getAttributes());
314  if (SrcF->hasGC())
315    setGC(SrcF->getGC());
316  else
317    clearGC();
318}
319
320/// getIntrinsicID - This method returns the ID number of the specified
321/// function, or Intrinsic::not_intrinsic if the function is not an
322/// intrinsic, or if the pointer is null.  This value is always defined to be
323/// zero to allow easy checking for whether a function is intrinsic or not.  The
324/// particular intrinsic functions which correspond to this value are defined in
325/// llvm/Intrinsics.h.
326///
327unsigned Function::getIntrinsicID() const {
328  const ValueName *ValName = this->getValueName();
329  if (!ValName || !isIntrinsic())
330    return 0;
331  unsigned Len = ValName->getKeyLength();
332  const char *Name = ValName->getKeyData();
333
334#define GET_FUNCTION_RECOGNIZER
335#include "llvm/IR/Intrinsics.gen"
336#undef GET_FUNCTION_RECOGNIZER
337  return 0;
338}
339
340std::string Intrinsic::getName(ID id, ArrayRef<Type*> Tys) {
341  assert(id < num_intrinsics && "Invalid intrinsic ID!");
342  static const char * const Table[] = {
343    "not_intrinsic",
344#define GET_INTRINSIC_NAME_TABLE
345#include "llvm/IR/Intrinsics.gen"
346#undef GET_INTRINSIC_NAME_TABLE
347  };
348  if (Tys.empty())
349    return Table[id];
350  std::string Result(Table[id]);
351  for (unsigned i = 0; i < Tys.size(); ++i) {
352    if (PointerType* PTyp = dyn_cast<PointerType>(Tys[i])) {
353      Result += ".p" + llvm::utostr(PTyp->getAddressSpace()) +
354                EVT::getEVT(PTyp->getElementType()).getEVTString();
355    }
356    else if (Tys[i])
357      Result += "." + EVT::getEVT(Tys[i]).getEVTString();
358  }
359  return Result;
360}
361
362
363/// IIT_Info - These are enumerators that describe the entries returned by the
364/// getIntrinsicInfoTableEntries function.
365///
366/// NOTE: This must be kept in synch with the copy in TblGen/IntrinsicEmitter!
367enum IIT_Info {
368  // Common values should be encoded with 0-15.
369  IIT_Done = 0,
370  IIT_I1   = 1,
371  IIT_I8   = 2,
372  IIT_I16  = 3,
373  IIT_I32  = 4,
374  IIT_I64  = 5,
375  IIT_F32  = 6,
376  IIT_F64  = 7,
377  IIT_V2   = 8,
378  IIT_V4   = 9,
379  IIT_V8   = 10,
380  IIT_V16  = 11,
381  IIT_V32  = 12,
382  IIT_MMX  = 13,
383  IIT_PTR  = 14,
384  IIT_ARG  = 15,
385
386  // Values from 16+ are only encodable with the inefficient encoding.
387  IIT_METADATA = 16,
388  IIT_EMPTYSTRUCT = 17,
389  IIT_STRUCT2 = 18,
390  IIT_STRUCT3 = 19,
391  IIT_STRUCT4 = 20,
392  IIT_STRUCT5 = 21,
393  IIT_EXTEND_VEC_ARG = 22,
394  IIT_TRUNC_VEC_ARG = 23,
395  IIT_ANYPTR = 24
396};
397
398
399static void DecodeIITType(unsigned &NextElt, ArrayRef<unsigned char> Infos,
400                      SmallVectorImpl<Intrinsic::IITDescriptor> &OutputTable) {
401  IIT_Info Info = IIT_Info(Infos[NextElt++]);
402  unsigned StructElts = 2;
403  using namespace Intrinsic;
404
405  switch (Info) {
406  case IIT_Done:
407    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Void, 0));
408    return;
409  case IIT_MMX:
410    OutputTable.push_back(IITDescriptor::get(IITDescriptor::MMX, 0));
411    return;
412  case IIT_METADATA:
413    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Metadata, 0));
414    return;
415  case IIT_F32:
416    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Float, 0));
417    return;
418  case IIT_F64:
419    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Double, 0));
420    return;
421  case IIT_I1:
422    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 1));
423    return;
424  case IIT_I8:
425    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 8));
426    return;
427  case IIT_I16:
428    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer,16));
429    return;
430  case IIT_I32:
431    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 32));
432    return;
433  case IIT_I64:
434    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 64));
435    return;
436  case IIT_V2:
437    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 2));
438    DecodeIITType(NextElt, Infos, OutputTable);
439    return;
440  case IIT_V4:
441    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 4));
442    DecodeIITType(NextElt, Infos, OutputTable);
443    return;
444  case IIT_V8:
445    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 8));
446    DecodeIITType(NextElt, Infos, OutputTable);
447    return;
448  case IIT_V16:
449    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 16));
450    DecodeIITType(NextElt, Infos, OutputTable);
451    return;
452  case IIT_V32:
453    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 32));
454    DecodeIITType(NextElt, Infos, OutputTable);
455    return;
456  case IIT_PTR:
457    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Pointer, 0));
458    DecodeIITType(NextElt, Infos, OutputTable);
459    return;
460  case IIT_ANYPTR: {  // [ANYPTR addrspace, subtype]
461    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Pointer,
462                                             Infos[NextElt++]));
463    DecodeIITType(NextElt, Infos, OutputTable);
464    return;
465  }
466  case IIT_ARG: {
467    unsigned ArgInfo = (NextElt == Infos.size() ? 0 : Infos[NextElt++]);
468    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Argument, ArgInfo));
469    return;
470  }
471  case IIT_EXTEND_VEC_ARG: {
472    unsigned ArgInfo = (NextElt == Infos.size() ? 0 : Infos[NextElt++]);
473    OutputTable.push_back(IITDescriptor::get(IITDescriptor::ExtendVecArgument,
474                                             ArgInfo));
475    return;
476  }
477  case IIT_TRUNC_VEC_ARG: {
478    unsigned ArgInfo = (NextElt == Infos.size() ? 0 : Infos[NextElt++]);
479    OutputTable.push_back(IITDescriptor::get(IITDescriptor::TruncVecArgument,
480                                             ArgInfo));
481    return;
482  }
483  case IIT_EMPTYSTRUCT:
484    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Struct, 0));
485    return;
486  case IIT_STRUCT5: ++StructElts; // FALL THROUGH.
487  case IIT_STRUCT4: ++StructElts; // FALL THROUGH.
488  case IIT_STRUCT3: ++StructElts; // FALL THROUGH.
489  case IIT_STRUCT2: {
490    OutputTable.push_back(IITDescriptor::get(IITDescriptor::Struct,StructElts));
491
492    for (unsigned i = 0; i != StructElts; ++i)
493      DecodeIITType(NextElt, Infos, OutputTable);
494    return;
495  }
496  }
497  llvm_unreachable("unhandled");
498}
499
500
501#define GET_INTRINSIC_GENERATOR_GLOBAL
502#include "llvm/IR/Intrinsics.gen"
503#undef GET_INTRINSIC_GENERATOR_GLOBAL
504
505void Intrinsic::getIntrinsicInfoTableEntries(ID id,
506                                             SmallVectorImpl<IITDescriptor> &T){
507  // Check to see if the intrinsic's type was expressible by the table.
508  unsigned TableVal = IIT_Table[id-1];
509
510  // Decode the TableVal into an array of IITValues.
511  SmallVector<unsigned char, 8> IITValues;
512  ArrayRef<unsigned char> IITEntries;
513  unsigned NextElt = 0;
514  if ((TableVal >> 31) != 0) {
515    // This is an offset into the IIT_LongEncodingTable.
516    IITEntries = IIT_LongEncodingTable;
517
518    // Strip sentinel bit.
519    NextElt = (TableVal << 1) >> 1;
520  } else {
521    // Decode the TableVal into an array of IITValues.  If the entry was encoded
522    // into a single word in the table itself, decode it now.
523    do {
524      IITValues.push_back(TableVal & 0xF);
525      TableVal >>= 4;
526    } while (TableVal);
527
528    IITEntries = IITValues;
529    NextElt = 0;
530  }
531
532  // Okay, decode the table into the output vector of IITDescriptors.
533  DecodeIITType(NextElt, IITEntries, T);
534  while (NextElt != IITEntries.size() && IITEntries[NextElt] != 0)
535    DecodeIITType(NextElt, IITEntries, T);
536}
537
538
539static Type *DecodeFixedType(ArrayRef<Intrinsic::IITDescriptor> &Infos,
540                             ArrayRef<Type*> Tys, LLVMContext &Context) {
541  using namespace Intrinsic;
542  IITDescriptor D = Infos.front();
543  Infos = Infos.slice(1);
544
545  switch (D.Kind) {
546  case IITDescriptor::Void: return Type::getVoidTy(Context);
547  case IITDescriptor::MMX: return Type::getX86_MMXTy(Context);
548  case IITDescriptor::Metadata: return Type::getMetadataTy(Context);
549  case IITDescriptor::Float: return Type::getFloatTy(Context);
550  case IITDescriptor::Double: return Type::getDoubleTy(Context);
551
552  case IITDescriptor::Integer:
553    return IntegerType::get(Context, D.Integer_Width);
554  case IITDescriptor::Vector:
555    return VectorType::get(DecodeFixedType(Infos, Tys, Context),D.Vector_Width);
556  case IITDescriptor::Pointer:
557    return PointerType::get(DecodeFixedType(Infos, Tys, Context),
558                            D.Pointer_AddressSpace);
559  case IITDescriptor::Struct: {
560    Type *Elts[5];
561    assert(D.Struct_NumElements <= 5 && "Can't handle this yet");
562    for (unsigned i = 0, e = D.Struct_NumElements; i != e; ++i)
563      Elts[i] = DecodeFixedType(Infos, Tys, Context);
564    return StructType::get(Context, ArrayRef<Type*>(Elts,D.Struct_NumElements));
565  }
566
567  case IITDescriptor::Argument:
568    return Tys[D.getArgumentNumber()];
569  case IITDescriptor::ExtendVecArgument:
570    return VectorType::getExtendedElementVectorType(cast<VectorType>(
571                                                  Tys[D.getArgumentNumber()]));
572
573  case IITDescriptor::TruncVecArgument:
574    return VectorType::getTruncatedElementVectorType(cast<VectorType>(
575                                                  Tys[D.getArgumentNumber()]));
576  }
577  llvm_unreachable("unhandled");
578}
579
580
581
582FunctionType *Intrinsic::getType(LLVMContext &Context,
583                                 ID id, ArrayRef<Type*> Tys) {
584  SmallVector<IITDescriptor, 8> Table;
585  getIntrinsicInfoTableEntries(id, Table);
586
587  ArrayRef<IITDescriptor> TableRef = Table;
588  Type *ResultTy = DecodeFixedType(TableRef, Tys, Context);
589
590  SmallVector<Type*, 8> ArgTys;
591  while (!TableRef.empty())
592    ArgTys.push_back(DecodeFixedType(TableRef, Tys, Context));
593
594  return FunctionType::get(ResultTy, ArgTys, false);
595}
596
597bool Intrinsic::isOverloaded(ID id) {
598#define GET_INTRINSIC_OVERLOAD_TABLE
599#include "llvm/IR/Intrinsics.gen"
600#undef GET_INTRINSIC_OVERLOAD_TABLE
601}
602
603/// This defines the "Intrinsic::getAttributes(ID id)" method.
604#define GET_INTRINSIC_ATTRIBUTES
605#include "llvm/IR/Intrinsics.gen"
606#undef GET_INTRINSIC_ATTRIBUTES
607
608Function *Intrinsic::getDeclaration(Module *M, ID id, ArrayRef<Type*> Tys) {
609  // There can never be multiple globals with the same name of different types,
610  // because intrinsics must be a specific type.
611  return
612    cast<Function>(M->getOrInsertFunction(getName(id, Tys),
613                                          getType(M->getContext(), id, Tys)));
614}
615
616// This defines the "Intrinsic::getIntrinsicForGCCBuiltin()" method.
617#define GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
618#include "llvm/IR/Intrinsics.gen"
619#undef GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
620
621/// hasAddressTaken - returns true if there are any uses of this function
622/// other than direct calls or invokes to it.
623bool Function::hasAddressTaken(const User* *PutOffender) const {
624  for (Value::const_use_iterator I = use_begin(), E = use_end(); I != E; ++I) {
625    const User *U = *I;
626    if (isa<BlockAddress>(U))
627      continue;
628    if (!isa<CallInst>(U) && !isa<InvokeInst>(U))
629      return PutOffender ? (*PutOffender = U, true) : true;
630    ImmutableCallSite CS(cast<Instruction>(U));
631    if (!CS.isCallee(I))
632      return PutOffender ? (*PutOffender = U, true) : true;
633  }
634  return false;
635}
636
637bool Function::isDefTriviallyDead() const {
638  // Check the linkage
639  if (!hasLinkOnceLinkage() && !hasLocalLinkage() &&
640      !hasAvailableExternallyLinkage())
641    return false;
642
643  // Check if the function is used by anything other than a blockaddress.
644  for (Value::const_use_iterator I = use_begin(), E = use_end(); I != E; ++I)
645    if (!isa<BlockAddress>(*I))
646      return false;
647
648  return true;
649}
650
651/// callsFunctionThatReturnsTwice - Return true if the function has a call to
652/// setjmp or other function that gcc recognizes as "returning twice".
653bool Function::callsFunctionThatReturnsTwice() const {
654  for (const_inst_iterator
655         I = inst_begin(this), E = inst_end(this); I != E; ++I) {
656    const CallInst* callInst = dyn_cast<CallInst>(&*I);
657    if (!callInst)
658      continue;
659    if (callInst->canReturnTwice())
660      return true;
661  }
662
663  return false;
664}
665
666