Home | History | Annotate | Download | only in IR 
      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 "LLVMContextImpl.h"
     16 #include "SymbolTableListTraitsImpl.h"
     17 #include "llvm/ADT/DenseMap.h"
     18 #include "llvm/ADT/STLExtras.h"
     19 #include "llvm/ADT/StringExtras.h"
     20 #include "llvm/CodeGen/ValueTypes.h"
     21 #include "llvm/IR/DerivedTypes.h"
     22 #include "llvm/IR/IntrinsicInst.h"
     23 #include "llvm/IR/LLVMContext.h"
     24 #include "llvm/IR/Module.h"
     25 #include "llvm/Support/CallSite.h"
     26 #include "llvm/Support/InstIterator.h"
     27 #include "llvm/Support/LeakDetector.h"
     28 #include "llvm/Support/ManagedStatic.h"
     29 #include "llvm/Support/RWMutex.h"
     30 #include "llvm/Support/StringPool.h"
     31 #include "llvm/Support/Threading.h"
     32 using namespace llvm;
     33 
     34 // Explicit instantiations of SymbolTableListTraits since some of the methods
     35 // are not in the public header file...
     36 template class llvm::SymbolTableListTraits<Argument, Function>;
     37 template class llvm::SymbolTableListTraits<BasicBlock, Function>;
     38 
     39 //===----------------------------------------------------------------------===//
     40 // Argument Implementation
     41 //===----------------------------------------------------------------------===//
     42 
     43 void Argument::anchor() { }
     44 
     45 Argument::Argument(Type *Ty, const Twine &Name, Function *Par)
     46   : Value(Ty, Value::ArgumentVal) {
     47   Parent = 0;
     48 
     49   // Make sure that we get added to a function
     50   LeakDetector::addGarbageObject(this);
     51 
     52   if (Par)
     53     Par->getArgumentList().push_back(this);
     54   setName(Name);
     55 }
     56 
     57 void Argument::setParent(Function *parent) {
     58   if (getParent())
     59     LeakDetector::addGarbageObject(this);
     60   Parent = parent;
     61   if (getParent())
     62     LeakDetector::removeGarbageObject(this);
     63 }
     64 
     65 /// getArgNo - Return the index of this formal argument in its containing
     66 /// function.  For example in "void foo(int a, float b)" a is 0 and b is 1.
     67 unsigned Argument::getArgNo() const {
     68   const Function *F = getParent();
     69   assert(F && "Argument is not in a function");
     70 
     71   Function::const_arg_iterator AI = F->arg_begin();
     72   unsigned ArgIdx = 0;
     73   for (; &*AI != this; ++AI)
     74     ++ArgIdx;
     75 
     76   return ArgIdx;
     77 }
     78 
     79 /// hasByValAttr - Return true if this argument has the byval attribute on it
     80 /// in its containing function.
     81 bool Argument::hasByValAttr() const {
     82   if (!getType()->isPointerTy()) return false;
     83   return getParent()->getAttributes().
     84     hasAttribute(getArgNo()+1, Attribute::ByVal);
     85 }
     86 
     87 unsigned Argument::getParamAlignment() const {
     88   assert(getType()->isPointerTy() && "Only pointers have alignments");
     89   return getParent()->getParamAlignment(getArgNo()+1);
     90 
     91 }
     92 
     93 /// hasNestAttr - Return true if this argument has the nest attribute on
     94 /// it in its containing function.
     95 bool Argument::hasNestAttr() const {
     96   if (!getType()->isPointerTy()) return false;
     97   return getParent()->getAttributes().
     98     hasAttribute(getArgNo()+1, Attribute::Nest);
     99 }
    100 
    101 /// hasNoAliasAttr - Return true if this argument has the noalias attribute on
    102 /// it in its containing function.
    103 bool Argument::hasNoAliasAttr() const {
    104   if (!getType()->isPointerTy()) return false;
    105   return getParent()->getAttributes().
    106     hasAttribute(getArgNo()+1, Attribute::NoAlias);
    107 }
    108 
    109 /// hasNoCaptureAttr - Return true if this argument has the nocapture attribute
    110 /// on it in its containing function.
    111 bool Argument::hasNoCaptureAttr() const {
    112   if (!getType()->isPointerTy()) return false;
    113   return getParent()->getAttributes().
    114     hasAttribute(getArgNo()+1, Attribute::NoCapture);
    115 }
    116 
    117 /// hasSRetAttr - Return true if this argument has the sret attribute on
    118 /// it in its containing function.
    119 bool Argument::hasStructRetAttr() const {
    120   if (!getType()->isPointerTy()) return false;
    121   if (this != getParent()->arg_begin())
    122     return false; // StructRet param must be first param
    123   return getParent()->getAttributes().
    124     hasAttribute(1, Attribute::StructRet);
    125 }
    126 
    127 /// hasReturnedAttr - Return true if this argument has the returned attribute on
    128 /// it in its containing function.
    129 bool Argument::hasReturnedAttr() const {
    130   return getParent()->getAttributes().
    131     hasAttribute(getArgNo()+1, Attribute::Returned);
    132 }
    133 
    134 /// Return true if this argument has the readonly or readnone attribute on it
    135 /// in its containing function.
    136 bool Argument::onlyReadsMemory() const {
    137   return getParent()->getAttributes().
    138       hasAttribute(getArgNo()+1, Attribute::ReadOnly) ||
    139       getParent()->getAttributes().
    140       hasAttribute(getArgNo()+1, Attribute::ReadNone);
    141 }
    142 
    143 /// addAttr - Add attributes to an argument.
    144 void Argument::addAttr(AttributeSet AS) {
    145   assert(AS.getNumSlots() <= 1 &&
    146          "Trying to add more than one attribute set to an argument!");
    147   AttrBuilder B(AS, AS.getSlotIndex(0));
    148   getParent()->addAttributes(getArgNo() + 1,
    149                              AttributeSet::get(Parent->getContext(),
    150                                                getArgNo() + 1, B));
    151 }
    152 
    153 /// removeAttr - Remove attributes from an argument.
    154 void Argument::removeAttr(AttributeSet AS) {
    155   assert(AS.getNumSlots() <= 1 &&
    156          "Trying to remove more than one attribute set from an argument!");
    157   AttrBuilder B(AS, AS.getSlotIndex(0));
    158   getParent()->removeAttributes(getArgNo() + 1,
    159                                 AttributeSet::get(Parent->getContext(),
    160                                                   getArgNo() + 1, B));
    161 }
    162 
    163 //===----------------------------------------------------------------------===//
    164 // Helper Methods in Function
    165 //===----------------------------------------------------------------------===//
    166 
    167 LLVMContext &Function::getContext() const {
    168   return getType()->getContext();
    169 }
    170 
    171 FunctionType *Function::getFunctionType() const {
    172   return cast<FunctionType>(getType()->getElementType());
    173 }
    174 
    175 bool Function::isVarArg() const {
    176   return getFunctionType()->isVarArg();
    177 }
    178 
    179 Type *Function::getReturnType() const {
    180   return getFunctionType()->getReturnType();
    181 }
    182 
    183 void Function::removeFromParent() {
    184   getParent()->getFunctionList().remove(this);
    185 }
    186 
    187 void Function::eraseFromParent() {
    188   getParent()->getFunctionList().erase(this);
    189 }
    190 
    191 //===----------------------------------------------------------------------===//
    192 // Function Implementation
    193 //===----------------------------------------------------------------------===//
    194 
    195 Function::Function(FunctionType *Ty, LinkageTypes Linkage,
    196                    const Twine &name, Module *ParentModule)
    197   : GlobalValue(PointerType::getUnqual(Ty),
    198                 Value::FunctionVal, 0, 0, Linkage, name) {
    199   assert(FunctionType::isValidReturnType(getReturnType()) &&
    200          "invalid return type");
    201   SymTab = new ValueSymbolTable();
    202 
    203   // If the function has arguments, mark them as lazily built.
    204   if (Ty->getNumParams())
    205     setValueSubclassData(1);   // Set the "has lazy arguments" bit.
    206 
    207   // Make sure that we get added to a function
    208   LeakDetector::addGarbageObject(this);
    209 
    210   if (ParentModule)
    211     ParentModule->getFunctionList().push_back(this);
    212 
    213   // Ensure intrinsics have the right parameter attributes.
    214   if (unsigned IID = getIntrinsicID())
    215     setAttributes(Intrinsic::getAttributes(getContext(), Intrinsic::ID(IID)));
    216 
    217 }
    218 
    219 Function::~Function() {
    220   dropAllReferences();    // After this it is safe to delete instructions.
    221 
    222   // Delete all of the method arguments and unlink from symbol table...
    223   ArgumentList.clear();
    224   delete SymTab;
    225 
    226   // Remove the function from the on-the-side GC table.
    227   clearGC();
    228 
    229   // Remove the intrinsicID from the Cache.
    230   if (getValueName() && isIntrinsic())
    231     getContext().pImpl->IntrinsicIDCache.erase(this);
    232 }
    233 
    234 void Function::BuildLazyArguments() const {
    235   // Create the arguments vector, all arguments start out unnamed.
    236   FunctionType *FT = getFunctionType();
    237   for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
    238     assert(!FT->getParamType(i)->isVoidTy() &&
    239            "Cannot have void typed arguments!");
    240     ArgumentList.push_back(new Argument(FT->getParamType(i)));
    241   }
    242 
    243   // Clear the lazy arguments bit.
    244   unsigned SDC = getSubclassDataFromValue();
    245   const_cast<Function*>(this)->setValueSubclassData(SDC &= ~1);
    246 }
    247 
    248 size_t Function::arg_size() const {
    249   return getFunctionType()->getNumParams();
    250 }
    251 bool Function::arg_empty() const {
    252   return getFunctionType()->getNumParams() == 0;
    253 }
    254 
    255 void Function::setParent(Module *parent) {
    256   if (getParent())
    257     LeakDetector::addGarbageObject(this);
    258   Parent = parent;
    259   if (getParent())
    260     LeakDetector::removeGarbageObject(this);
    261 }
    262 
    263 // dropAllReferences() - This function causes all the subinstructions to "let
    264 // go" of all references that they are maintaining.  This allows one to
    265 // 'delete' a whole class at a time, even though there may be circular
    266 // references... first all references are dropped, and all use counts go to
    267 // zero.  Then everything is deleted for real.  Note that no operations are
    268 // valid on an object that has "dropped all references", except operator
    269 // delete.
    270 //
    271 void Function::dropAllReferences() {
    272   for (iterator I = begin(), E = end(); I != E; ++I)
    273     I->dropAllReferences();
    274 
    275   // Delete all basic blocks. They are now unused, except possibly by
    276   // blockaddresses, but BasicBlock's destructor takes care of those.
    277   while (!BasicBlocks.empty())
    278     BasicBlocks.begin()->eraseFromParent();
    279 }
    280 
    281 void Function::addAttribute(unsigned i, Attribute::AttrKind attr) {
    282   AttributeSet PAL = getAttributes();
    283   PAL = PAL.addAttribute(getContext(), i, attr);
    284   setAttributes(PAL);
    285 }
    286 
    287 void Function::addAttributes(unsigned i, AttributeSet attrs) {
    288   AttributeSet PAL = getAttributes();
    289   PAL = PAL.addAttributes(getContext(), i, attrs);
    290   setAttributes(PAL);
    291 }
    292 
    293 void Function::removeAttributes(unsigned i, AttributeSet attrs) {
    294   AttributeSet PAL = getAttributes();
    295   PAL = PAL.removeAttributes(getContext(), i, attrs);
    296   setAttributes(PAL);
    297 }
    298 
    299 // Maintain the GC name for each function in an on-the-side table. This saves
    300 // allocating an additional word in Function for programs which do not use GC
    301 // (i.e., most programs) at the cost of increased overhead for clients which do
    302 // use GC.
    303 static DenseMap<const Function*,PooledStringPtr> *GCNames;
    304 static StringPool *GCNamePool;
    305 static ManagedStatic<sys::SmartRWMutex<true> > GCLock;
    306 
    307 bool Function::hasGC() const {
    308   sys::SmartScopedReader<true> Reader(*GCLock);
    309   return GCNames && GCNames->count(this);
    310 }
    311 
    312 const char *Function::getGC() const {
    313   assert(hasGC() && "Function has no collector");
    314   sys::SmartScopedReader<true> Reader(*GCLock);
    315   return *(*GCNames)[this];
    316 }
    317 
    318 void Function::setGC(const char *Str) {
    319   sys::SmartScopedWriter<true> Writer(*GCLock);
    320   if (!GCNamePool)
    321     GCNamePool = new StringPool();
    322   if (!GCNames)
    323     GCNames = new DenseMap<const Function*,PooledStringPtr>();
    324   (*GCNames)[this] = GCNamePool->intern(Str);
    325 }
    326 
    327 void Function::clearGC() {
    328   sys::SmartScopedWriter<true> Writer(*GCLock);
    329   if (GCNames) {
    330     GCNames->erase(this);
    331     if (GCNames->empty()) {
    332       delete GCNames;
    333       GCNames = 0;
    334       if (GCNamePool->empty()) {
    335         delete GCNamePool;
    336         GCNamePool = 0;
    337       }
    338     }
    339   }
    340 }
    341 
    342 /// copyAttributesFrom - copy all additional attributes (those not needed to
    343 /// create a Function) from the Function Src to this one.
    344 void Function::copyAttributesFrom(const GlobalValue *Src) {
    345   assert(isa<Function>(Src) && "Expected a Function!");
    346   GlobalValue::copyAttributesFrom(Src);
    347   const Function *SrcF = cast<Function>(Src);
    348   setCallingConv(SrcF->getCallingConv());
    349   setAttributes(SrcF->getAttributes());
    350   if (SrcF->hasGC())
    351     setGC(SrcF->getGC());
    352   else
    353     clearGC();
    354 }
    355 
    356 /// getIntrinsicID - This method returns the ID number of the specified
    357 /// function, or Intrinsic::not_intrinsic if the function is not an
    358 /// intrinsic, or if the pointer is null.  This value is always defined to be
    359 /// zero to allow easy checking for whether a function is intrinsic or not.  The
    360 /// particular intrinsic functions which correspond to this value are defined in
    361 /// llvm/Intrinsics.h.  Results are cached in the LLVM context, subsequent
    362 /// requests for the same ID return results much faster from the cache.
    363 ///
    364 unsigned Function::getIntrinsicID() const {
    365   const ValueName *ValName = this->getValueName();
    366   if (!ValName || !isIntrinsic())
    367     return 0;
    368 
    369   LLVMContextImpl::IntrinsicIDCacheTy &IntrinsicIDCache =
    370     getContext().pImpl->IntrinsicIDCache;
    371   if (!IntrinsicIDCache.count(this)) {
    372     unsigned Id = lookupIntrinsicID();
    373     IntrinsicIDCache[this]=Id;
    374     return Id;
    375   }
    376   return IntrinsicIDCache[this];
    377 }
    378 
    379 /// This private method does the actual lookup of an intrinsic ID when the query
    380 /// could not be answered from the cache.
    381 unsigned Function::lookupIntrinsicID() const {
    382   const ValueName *ValName = this->getValueName();
    383   unsigned Len = ValName->getKeyLength();
    384   const char *Name = ValName->getKeyData();
    385 
    386 #define GET_FUNCTION_RECOGNIZER
    387 #include "llvm/IR/Intrinsics.gen"
    388 #undef GET_FUNCTION_RECOGNIZER
    389 
    390   return 0;
    391 }
    392 
    393 std::string Intrinsic::getName(ID id, ArrayRef<Type*> Tys) {
    394   assert(id < num_intrinsics && "Invalid intrinsic ID!");
    395   static const char * const Table[] = {
    396     "not_intrinsic",
    397 #define GET_INTRINSIC_NAME_TABLE
    398 #include "llvm/IR/Intrinsics.gen"
    399 #undef GET_INTRINSIC_NAME_TABLE
    400   };
    401   if (Tys.empty())
    402     return Table[id];
    403   std::string Result(Table[id]);
    404   for (unsigned i = 0; i < Tys.size(); ++i) {
    405     if (PointerType* PTyp = dyn_cast<PointerType>(Tys[i])) {
    406       Result += ".p" + llvm::utostr(PTyp->getAddressSpace()) +
    407                 EVT::getEVT(PTyp->getElementType()).getEVTString();
    408     }
    409     else if (Tys[i])
    410       Result += "." + EVT::getEVT(Tys[i]).getEVTString();
    411   }
    412   return Result;
    413 }
    414 
    415 
    416 /// IIT_Info - These are enumerators that describe the entries returned by the
    417 /// getIntrinsicInfoTableEntries function.
    418 ///
    419 /// NOTE: This must be kept in synch with the copy in TblGen/IntrinsicEmitter!
    420 enum IIT_Info {
    421   // Common values should be encoded with 0-15.
    422   IIT_Done = 0,
    423   IIT_I1   = 1,
    424   IIT_I8   = 2,
    425   IIT_I16  = 3,
    426   IIT_I32  = 4,
    427   IIT_I64  = 5,
    428   IIT_F16  = 6,
    429   IIT_F32  = 7,
    430   IIT_F64  = 8,
    431   IIT_V2   = 9,
    432   IIT_V4   = 10,
    433   IIT_V8   = 11,
    434   IIT_V16  = 12,
    435   IIT_V32  = 13,
    436   IIT_PTR  = 14,
    437   IIT_ARG  = 15,
    438 
    439   // Values from 16+ are only encodable with the inefficient encoding.
    440   IIT_MMX  = 16,
    441   IIT_METADATA = 17,
    442   IIT_EMPTYSTRUCT = 18,
    443   IIT_STRUCT2 = 19,
    444   IIT_STRUCT3 = 20,
    445   IIT_STRUCT4 = 21,
    446   IIT_STRUCT5 = 22,
    447   IIT_EXTEND_VEC_ARG = 23,
    448   IIT_TRUNC_VEC_ARG = 24,
    449   IIT_ANYPTR = 25
    450 };
    451 
    452 
    453 static void DecodeIITType(unsigned &NextElt, ArrayRef<unsigned char> Infos,
    454                       SmallVectorImpl<Intrinsic::IITDescriptor> &OutputTable) {
    455   IIT_Info Info = IIT_Info(Infos[NextElt++]);
    456   unsigned StructElts = 2;
    457   using namespace Intrinsic;
    458 
    459   switch (Info) {
    460   case IIT_Done:
    461     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Void, 0));
    462     return;
    463   case IIT_MMX:
    464     OutputTable.push_back(IITDescriptor::get(IITDescriptor::MMX, 0));
    465     return;
    466   case IIT_METADATA:
    467     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Metadata, 0));
    468     return;
    469   case IIT_F16:
    470     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Half, 0));
    471     return;
    472   case IIT_F32:
    473     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Float, 0));
    474     return;
    475   case IIT_F64:
    476     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Double, 0));
    477     return;
    478   case IIT_I1:
    479     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 1));
    480     return;
    481   case IIT_I8:
    482     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 8));
    483     return;
    484   case IIT_I16:
    485     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer,16));
    486     return;
    487   case IIT_I32:
    488     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 32));
    489     return;
    490   case IIT_I64:
    491     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 64));
    492     return;
    493   case IIT_V2:
    494     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 2));
    495     DecodeIITType(NextElt, Infos, OutputTable);
    496     return;
    497   case IIT_V4:
    498     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 4));
    499     DecodeIITType(NextElt, Infos, OutputTable);
    500     return;
    501   case IIT_V8:
    502     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 8));
    503     DecodeIITType(NextElt, Infos, OutputTable);
    504     return;
    505   case IIT_V16:
    506     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 16));
    507     DecodeIITType(NextElt, Infos, OutputTable);
    508     return;
    509   case IIT_V32:
    510     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 32));
    511     DecodeIITType(NextElt, Infos, OutputTable);
    512     return;
    513   case IIT_PTR:
    514     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Pointer, 0));
    515     DecodeIITType(NextElt, Infos, OutputTable);
    516     return;
    517   case IIT_ANYPTR: {  // [ANYPTR addrspace, subtype]
    518     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Pointer,
    519                                              Infos[NextElt++]));
    520     DecodeIITType(NextElt, Infos, OutputTable);
    521     return;
    522   }
    523   case IIT_ARG: {
    524     unsigned ArgInfo = (NextElt == Infos.size() ? 0 : Infos[NextElt++]);
    525     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Argument, ArgInfo));
    526     return;
    527   }
    528   case IIT_EXTEND_VEC_ARG: {
    529     unsigned ArgInfo = (NextElt == Infos.size() ? 0 : Infos[NextElt++]);
    530     OutputTable.push_back(IITDescriptor::get(IITDescriptor::ExtendVecArgument,
    531                                              ArgInfo));
    532     return;
    533   }
    534   case IIT_TRUNC_VEC_ARG: {
    535     unsigned ArgInfo = (NextElt == Infos.size() ? 0 : Infos[NextElt++]);
    536     OutputTable.push_back(IITDescriptor::get(IITDescriptor::TruncVecArgument,
    537                                              ArgInfo));
    538     return;
    539   }
    540   case IIT_EMPTYSTRUCT:
    541     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Struct, 0));
    542     return;
    543   case IIT_STRUCT5: ++StructElts; // FALL THROUGH.
    544   case IIT_STRUCT4: ++StructElts; // FALL THROUGH.
    545   case IIT_STRUCT3: ++StructElts; // FALL THROUGH.
    546   case IIT_STRUCT2: {
    547     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Struct,StructElts));
    548 
    549     for (unsigned i = 0; i != StructElts; ++i)
    550       DecodeIITType(NextElt, Infos, OutputTable);
    551     return;
    552   }
    553   }
    554   llvm_unreachable("unhandled");
    555 }
    556 
    557 
    558 #define GET_INTRINSIC_GENERATOR_GLOBAL
    559 #include "llvm/IR/Intrinsics.gen"
    560 #undef GET_INTRINSIC_GENERATOR_GLOBAL
    561 
    562 void Intrinsic::getIntrinsicInfoTableEntries(ID id,
    563                                              SmallVectorImpl<IITDescriptor> &T){
    564   // Check to see if the intrinsic's type was expressible by the table.
    565   unsigned TableVal = IIT_Table[id-1];
    566 
    567   // Decode the TableVal into an array of IITValues.
    568   SmallVector<unsigned char, 8> IITValues;
    569   ArrayRef<unsigned char> IITEntries;
    570   unsigned NextElt = 0;
    571   if ((TableVal >> 31) != 0) {
    572     // This is an offset into the IIT_LongEncodingTable.
    573     IITEntries = IIT_LongEncodingTable;
    574 
    575     // Strip sentinel bit.
    576     NextElt = (TableVal << 1) >> 1;
    577   } else {
    578     // Decode the TableVal into an array of IITValues.  If the entry was encoded
    579     // into a single word in the table itself, decode it now.
    580     do {
    581       IITValues.push_back(TableVal & 0xF);
    582       TableVal >>= 4;
    583     } while (TableVal);
    584 
    585     IITEntries = IITValues;
    586     NextElt = 0;
    587   }
    588 
    589   // Okay, decode the table into the output vector of IITDescriptors.
    590   DecodeIITType(NextElt, IITEntries, T);
    591   while (NextElt != IITEntries.size() && IITEntries[NextElt] != 0)
    592     DecodeIITType(NextElt, IITEntries, T);
    593 }
    594 
    595 
    596 static Type *DecodeFixedType(ArrayRef<Intrinsic::IITDescriptor> &Infos,
    597                              ArrayRef<Type*> Tys, LLVMContext &Context) {
    598   using namespace Intrinsic;
    599   IITDescriptor D = Infos.front();
    600   Infos = Infos.slice(1);
    601 
    602   switch (D.Kind) {
    603   case IITDescriptor::Void: return Type::getVoidTy(Context);
    604   case IITDescriptor::MMX: return Type::getX86_MMXTy(Context);
    605   case IITDescriptor::Metadata: return Type::getMetadataTy(Context);
    606   case IITDescriptor::Half: return Type::getHalfTy(Context);
    607   case IITDescriptor::Float: return Type::getFloatTy(Context);
    608   case IITDescriptor::Double: return Type::getDoubleTy(Context);
    609 
    610   case IITDescriptor::Integer:
    611     return IntegerType::get(Context, D.Integer_Width);
    612   case IITDescriptor::Vector:
    613     return VectorType::get(DecodeFixedType(Infos, Tys, Context),D.Vector_Width);
    614   case IITDescriptor::Pointer:
    615     return PointerType::get(DecodeFixedType(Infos, Tys, Context),
    616                             D.Pointer_AddressSpace);
    617   case IITDescriptor::Struct: {
    618     Type *Elts[5];
    619     assert(D.Struct_NumElements <= 5 && "Can't handle this yet");
    620     for (unsigned i = 0, e = D.Struct_NumElements; i != e; ++i)
    621       Elts[i] = DecodeFixedType(Infos, Tys, Context);
    622     return StructType::get(Context, ArrayRef<Type*>(Elts,D.Struct_NumElements));
    623   }
    624 
    625   case IITDescriptor::Argument:
    626     return Tys[D.getArgumentNumber()];
    627   case IITDescriptor::ExtendVecArgument:
    628     return VectorType::getExtendedElementVectorType(cast<VectorType>(
    629                                                   Tys[D.getArgumentNumber()]));
    630 
    631   case IITDescriptor::TruncVecArgument:
    632     return VectorType::getTruncatedElementVectorType(cast<VectorType>(
    633                                                   Tys[D.getArgumentNumber()]));
    634   }
    635   llvm_unreachable("unhandled");
    636 }
    637 
    638 
    639 
    640 FunctionType *Intrinsic::getType(LLVMContext &Context,
    641                                  ID id, ArrayRef<Type*> Tys) {
    642   SmallVector<IITDescriptor, 8> Table;
    643   getIntrinsicInfoTableEntries(id, Table);
    644 
    645   ArrayRef<IITDescriptor> TableRef = Table;
    646   Type *ResultTy = DecodeFixedType(TableRef, Tys, Context);
    647 
    648   SmallVector<Type*, 8> ArgTys;
    649   while (!TableRef.empty())
    650     ArgTys.push_back(DecodeFixedType(TableRef, Tys, Context));
    651 
    652   return FunctionType::get(ResultTy, ArgTys, false);
    653 }
    654 
    655 bool Intrinsic::isOverloaded(ID id) {
    656 #define GET_INTRINSIC_OVERLOAD_TABLE
    657 #include "llvm/IR/Intrinsics.gen"
    658 #undef GET_INTRINSIC_OVERLOAD_TABLE
    659 }
    660 
    661 /// This defines the "Intrinsic::getAttributes(ID id)" method.
    662 #define GET_INTRINSIC_ATTRIBUTES
    663 #include "llvm/IR/Intrinsics.gen"
    664 #undef GET_INTRINSIC_ATTRIBUTES
    665 
    666 Function *Intrinsic::getDeclaration(Module *M, ID id, ArrayRef<Type*> Tys) {
    667   // There can never be multiple globals with the same name of different types,
    668   // because intrinsics must be a specific type.
    669   return
    670     cast<Function>(M->getOrInsertFunction(getName(id, Tys),
    671                                           getType(M->getContext(), id, Tys)));
    672 }
    673 
    674 // This defines the "Intrinsic::getIntrinsicForGCCBuiltin()" method.
    675 #define GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
    676 #include "llvm/IR/Intrinsics.gen"
    677 #undef GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
    678 
    679 /// hasAddressTaken - returns true if there are any uses of this function
    680 /// other than direct calls or invokes to it.
    681 bool Function::hasAddressTaken(const User* *PutOffender) const {
    682   for (Value::const_use_iterator I = use_begin(), E = use_end(); I != E; ++I) {
    683     const User *U = *I;
    684     if (isa<BlockAddress>(U))
    685       continue;
    686     if (!isa<CallInst>(U) && !isa<InvokeInst>(U))
    687       return PutOffender ? (*PutOffender = U, true) : true;
    688     ImmutableCallSite CS(cast<Instruction>(U));
    689     if (!CS.isCallee(I))
    690       return PutOffender ? (*PutOffender = U, true) : true;
    691   }
    692   return false;
    693 }
    694 
    695 bool Function::isDefTriviallyDead() const {
    696   // Check the linkage
    697   if (!hasLinkOnceLinkage() && !hasLocalLinkage() &&
    698       !hasAvailableExternallyLinkage())
    699     return false;
    700 
    701   // Check if the function is used by anything other than a blockaddress.
    702   for (Value::const_use_iterator I = use_begin(), E = use_end(); I != E; ++I)
    703     if (!isa<BlockAddress>(*I))
    704       return false;
    705 
    706   return true;
    707 }
    708 
    709 /// callsFunctionThatReturnsTwice - Return true if the function has a call to
    710 /// setjmp or other function that gcc recognizes as "returning twice".
    711 bool Function::callsFunctionThatReturnsTwice() const {
    712   for (const_inst_iterator
    713          I = inst_begin(this), E = inst_end(this); I != E; ++I) {
    714     const CallInst* callInst = dyn_cast<CallInst>(&*I);
    715     if (!callInst)
    716       continue;
    717     if (callInst->canReturnTwice())
    718       return true;
    719   }
    720 
    721   return false;
    722 }
    723