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      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/CallSite.h"
     22 #include "llvm/IR/DerivedTypes.h"
     23 #include "llvm/IR/InstIterator.h"
     24 #include "llvm/IR/IntrinsicInst.h"
     25 #include "llvm/IR/LLVMContext.h"
     26 #include "llvm/IR/LeakDetector.h"
     27 #include "llvm/IR/Module.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 = nullptr;
     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 /// hasNonNullAttr - Return true if this argument has the nonnull attribute on
     80 /// it in its containing function.
     81 bool Argument::hasNonNullAttr() const {
     82   if (!getType()->isPointerTy()) return false;
     83   return getParent()->getAttributes().
     84     hasAttribute(getArgNo()+1, Attribute::NonNull);
     85 }
     86 
     87 /// hasByValAttr - Return true if this argument has the byval attribute on it
     88 /// in its containing function.
     89 bool Argument::hasByValAttr() const {
     90   if (!getType()->isPointerTy()) return false;
     91   return getParent()->getAttributes().
     92     hasAttribute(getArgNo()+1, Attribute::ByVal);
     93 }
     94 
     95 /// \brief Return true if this argument has the inalloca attribute on it in
     96 /// its containing function.
     97 bool Argument::hasInAllocaAttr() const {
     98   if (!getType()->isPointerTy()) return false;
     99   return getParent()->getAttributes().
    100     hasAttribute(getArgNo()+1, Attribute::InAlloca);
    101 }
    102 
    103 bool Argument::hasByValOrInAllocaAttr() const {
    104   if (!getType()->isPointerTy()) return false;
    105   AttributeSet Attrs = getParent()->getAttributes();
    106   return Attrs.hasAttribute(getArgNo() + 1, Attribute::ByVal) ||
    107          Attrs.hasAttribute(getArgNo() + 1, Attribute::InAlloca);
    108 }
    109 
    110 unsigned Argument::getParamAlignment() const {
    111   assert(getType()->isPointerTy() && "Only pointers have alignments");
    112   return getParent()->getParamAlignment(getArgNo()+1);
    113 
    114 }
    115 
    116 /// hasNestAttr - Return true if this argument has the nest attribute on
    117 /// it in its containing function.
    118 bool Argument::hasNestAttr() const {
    119   if (!getType()->isPointerTy()) return false;
    120   return getParent()->getAttributes().
    121     hasAttribute(getArgNo()+1, Attribute::Nest);
    122 }
    123 
    124 /// hasNoAliasAttr - Return true if this argument has the noalias attribute on
    125 /// it in its containing function.
    126 bool Argument::hasNoAliasAttr() const {
    127   if (!getType()->isPointerTy()) return false;
    128   return getParent()->getAttributes().
    129     hasAttribute(getArgNo()+1, Attribute::NoAlias);
    130 }
    131 
    132 /// hasNoCaptureAttr - Return true if this argument has the nocapture attribute
    133 /// on it in its containing function.
    134 bool Argument::hasNoCaptureAttr() const {
    135   if (!getType()->isPointerTy()) return false;
    136   return getParent()->getAttributes().
    137     hasAttribute(getArgNo()+1, Attribute::NoCapture);
    138 }
    139 
    140 /// hasSRetAttr - Return true if this argument has the sret attribute on
    141 /// it in its containing function.
    142 bool Argument::hasStructRetAttr() const {
    143   if (!getType()->isPointerTy()) return false;
    144   if (this != getParent()->arg_begin())
    145     return false; // StructRet param must be first param
    146   return getParent()->getAttributes().
    147     hasAttribute(1, Attribute::StructRet);
    148 }
    149 
    150 /// hasReturnedAttr - Return true if this argument has the returned attribute on
    151 /// it in its containing function.
    152 bool Argument::hasReturnedAttr() const {
    153   return getParent()->getAttributes().
    154     hasAttribute(getArgNo()+1, Attribute::Returned);
    155 }
    156 
    157 /// Return true if this argument has the readonly or readnone attribute on it
    158 /// in its containing function.
    159 bool Argument::onlyReadsMemory() const {
    160   return getParent()->getAttributes().
    161       hasAttribute(getArgNo()+1, Attribute::ReadOnly) ||
    162       getParent()->getAttributes().
    163       hasAttribute(getArgNo()+1, Attribute::ReadNone);
    164 }
    165 
    166 /// addAttr - Add attributes to an argument.
    167 void Argument::addAttr(AttributeSet AS) {
    168   assert(AS.getNumSlots() <= 1 &&
    169          "Trying to add more than one attribute set to an argument!");
    170   AttrBuilder B(AS, AS.getSlotIndex(0));
    171   getParent()->addAttributes(getArgNo() + 1,
    172                              AttributeSet::get(Parent->getContext(),
    173                                                getArgNo() + 1, B));
    174 }
    175 
    176 /// removeAttr - Remove attributes from an argument.
    177 void Argument::removeAttr(AttributeSet AS) {
    178   assert(AS.getNumSlots() <= 1 &&
    179          "Trying to remove more than one attribute set from an argument!");
    180   AttrBuilder B(AS, AS.getSlotIndex(0));
    181   getParent()->removeAttributes(getArgNo() + 1,
    182                                 AttributeSet::get(Parent->getContext(),
    183                                                   getArgNo() + 1, B));
    184 }
    185 
    186 //===----------------------------------------------------------------------===//
    187 // Helper Methods in Function
    188 //===----------------------------------------------------------------------===//
    189 
    190 LLVMContext &Function::getContext() const {
    191   return getType()->getContext();
    192 }
    193 
    194 FunctionType *Function::getFunctionType() const {
    195   return cast<FunctionType>(getType()->getElementType());
    196 }
    197 
    198 bool Function::isVarArg() const {
    199   return getFunctionType()->isVarArg();
    200 }
    201 
    202 Type *Function::getReturnType() const {
    203   return getFunctionType()->getReturnType();
    204 }
    205 
    206 void Function::removeFromParent() {
    207   getParent()->getFunctionList().remove(this);
    208 }
    209 
    210 void Function::eraseFromParent() {
    211   getParent()->getFunctionList().erase(this);
    212 }
    213 
    214 //===----------------------------------------------------------------------===//
    215 // Function Implementation
    216 //===----------------------------------------------------------------------===//
    217 
    218 Function::Function(FunctionType *Ty, LinkageTypes Linkage,
    219                    const Twine &name, Module *ParentModule)
    220   : GlobalObject(PointerType::getUnqual(Ty),
    221                 Value::FunctionVal, nullptr, 0, Linkage, name) {
    222   assert(FunctionType::isValidReturnType(getReturnType()) &&
    223          "invalid return type");
    224   SymTab = new ValueSymbolTable();
    225 
    226   // If the function has arguments, mark them as lazily built.
    227   if (Ty->getNumParams())
    228     setValueSubclassData(1);   // Set the "has lazy arguments" bit.
    229 
    230   // Make sure that we get added to a function
    231   LeakDetector::addGarbageObject(this);
    232 
    233   if (ParentModule)
    234     ParentModule->getFunctionList().push_back(this);
    235 
    236   // Ensure intrinsics have the right parameter attributes.
    237   if (unsigned IID = getIntrinsicID())
    238     setAttributes(Intrinsic::getAttributes(getContext(), Intrinsic::ID(IID)));
    239 
    240 }
    241 
    242 Function::~Function() {
    243   dropAllReferences();    // After this it is safe to delete instructions.
    244 
    245   // Delete all of the method arguments and unlink from symbol table...
    246   ArgumentList.clear();
    247   delete SymTab;
    248 
    249   // Remove the function from the on-the-side GC table.
    250   clearGC();
    251 
    252   // Remove the intrinsicID from the Cache.
    253   if (getValueName() && isIntrinsic())
    254     getContext().pImpl->IntrinsicIDCache.erase(this);
    255 }
    256 
    257 void Function::BuildLazyArguments() const {
    258   // Create the arguments vector, all arguments start out unnamed.
    259   FunctionType *FT = getFunctionType();
    260   for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
    261     assert(!FT->getParamType(i)->isVoidTy() &&
    262            "Cannot have void typed arguments!");
    263     ArgumentList.push_back(new Argument(FT->getParamType(i)));
    264   }
    265 
    266   // Clear the lazy arguments bit.
    267   unsigned SDC = getSubclassDataFromValue();
    268   const_cast<Function*>(this)->setValueSubclassData(SDC &= ~1);
    269 }
    270 
    271 size_t Function::arg_size() const {
    272   return getFunctionType()->getNumParams();
    273 }
    274 bool Function::arg_empty() const {
    275   return getFunctionType()->getNumParams() == 0;
    276 }
    277 
    278 void Function::setParent(Module *parent) {
    279   if (getParent())
    280     LeakDetector::addGarbageObject(this);
    281   Parent = parent;
    282   if (getParent())
    283     LeakDetector::removeGarbageObject(this);
    284 }
    285 
    286 // dropAllReferences() - This function causes all the subinstructions to "let
    287 // go" of all references that they are maintaining.  This allows one to
    288 // 'delete' a whole class at a time, even though there may be circular
    289 // references... first all references are dropped, and all use counts go to
    290 // zero.  Then everything is deleted for real.  Note that no operations are
    291 // valid on an object that has "dropped all references", except operator
    292 // delete.
    293 //
    294 void Function::dropAllReferences() {
    295   for (iterator I = begin(), E = end(); I != E; ++I)
    296     I->dropAllReferences();
    297 
    298   // Delete all basic blocks. They are now unused, except possibly by
    299   // blockaddresses, but BasicBlock's destructor takes care of those.
    300   while (!BasicBlocks.empty())
    301     BasicBlocks.begin()->eraseFromParent();
    302 
    303   // Prefix data is stored in a side table.
    304   setPrefixData(nullptr);
    305 }
    306 
    307 void Function::addAttribute(unsigned i, Attribute::AttrKind attr) {
    308   AttributeSet PAL = getAttributes();
    309   PAL = PAL.addAttribute(getContext(), i, attr);
    310   setAttributes(PAL);
    311 }
    312 
    313 void Function::addAttributes(unsigned i, AttributeSet attrs) {
    314   AttributeSet PAL = getAttributes();
    315   PAL = PAL.addAttributes(getContext(), i, attrs);
    316   setAttributes(PAL);
    317 }
    318 
    319 void Function::removeAttributes(unsigned i, AttributeSet attrs) {
    320   AttributeSet PAL = getAttributes();
    321   PAL = PAL.removeAttributes(getContext(), i, attrs);
    322   setAttributes(PAL);
    323 }
    324 
    325 // Maintain the GC name for each function in an on-the-side table. This saves
    326 // allocating an additional word in Function for programs which do not use GC
    327 // (i.e., most programs) at the cost of increased overhead for clients which do
    328 // use GC.
    329 static DenseMap<const Function*,PooledStringPtr> *GCNames;
    330 static StringPool *GCNamePool;
    331 static ManagedStatic<sys::SmartRWMutex<true> > GCLock;
    332 
    333 bool Function::hasGC() const {
    334   sys::SmartScopedReader<true> Reader(*GCLock);
    335   return GCNames && GCNames->count(this);
    336 }
    337 
    338 const char *Function::getGC() const {
    339   assert(hasGC() && "Function has no collector");
    340   sys::SmartScopedReader<true> Reader(*GCLock);
    341   return *(*GCNames)[this];
    342 }
    343 
    344 void Function::setGC(const char *Str) {
    345   sys::SmartScopedWriter<true> Writer(*GCLock);
    346   if (!GCNamePool)
    347     GCNamePool = new StringPool();
    348   if (!GCNames)
    349     GCNames = new DenseMap<const Function*,PooledStringPtr>();
    350   (*GCNames)[this] = GCNamePool->intern(Str);
    351 }
    352 
    353 void Function::clearGC() {
    354   sys::SmartScopedWriter<true> Writer(*GCLock);
    355   if (GCNames) {
    356     GCNames->erase(this);
    357     if (GCNames->empty()) {
    358       delete GCNames;
    359       GCNames = nullptr;
    360       if (GCNamePool->empty()) {
    361         delete GCNamePool;
    362         GCNamePool = nullptr;
    363       }
    364     }
    365   }
    366 }
    367 
    368 /// copyAttributesFrom - copy all additional attributes (those not needed to
    369 /// create a Function) from the Function Src to this one.
    370 void Function::copyAttributesFrom(const GlobalValue *Src) {
    371   assert(isa<Function>(Src) && "Expected a Function!");
    372   GlobalObject::copyAttributesFrom(Src);
    373   const Function *SrcF = cast<Function>(Src);
    374   setCallingConv(SrcF->getCallingConv());
    375   setAttributes(SrcF->getAttributes());
    376   if (SrcF->hasGC())
    377     setGC(SrcF->getGC());
    378   else
    379     clearGC();
    380   if (SrcF->hasPrefixData())
    381     setPrefixData(SrcF->getPrefixData());
    382   else
    383     setPrefixData(nullptr);
    384 }
    385 
    386 /// getIntrinsicID - This method returns the ID number of the specified
    387 /// function, or Intrinsic::not_intrinsic if the function is not an
    388 /// intrinsic, or if the pointer is null.  This value is always defined to be
    389 /// zero to allow easy checking for whether a function is intrinsic or not.  The
    390 /// particular intrinsic functions which correspond to this value are defined in
    391 /// llvm/Intrinsics.h.  Results are cached in the LLVM context, subsequent
    392 /// requests for the same ID return results much faster from the cache.
    393 ///
    394 unsigned Function::getIntrinsicID() const {
    395   const ValueName *ValName = this->getValueName();
    396   if (!ValName || !isIntrinsic())
    397     return 0;
    398 
    399   LLVMContextImpl::IntrinsicIDCacheTy &IntrinsicIDCache =
    400     getContext().pImpl->IntrinsicIDCache;
    401   if (!IntrinsicIDCache.count(this)) {
    402     unsigned Id = lookupIntrinsicID();
    403     IntrinsicIDCache[this]=Id;
    404     return Id;
    405   }
    406   return IntrinsicIDCache[this];
    407 }
    408 
    409 /// This private method does the actual lookup of an intrinsic ID when the query
    410 /// could not be answered from the cache.
    411 unsigned Function::lookupIntrinsicID() const {
    412   const ValueName *ValName = this->getValueName();
    413   unsigned Len = ValName->getKeyLength();
    414   const char *Name = ValName->getKeyData();
    415 
    416 #define GET_FUNCTION_RECOGNIZER
    417 #include "llvm/IR/Intrinsics.gen"
    418 #undef GET_FUNCTION_RECOGNIZER
    419 
    420   return 0;
    421 }
    422 
    423 std::string Intrinsic::getName(ID id, ArrayRef<Type*> Tys) {
    424   assert(id < num_intrinsics && "Invalid intrinsic ID!");
    425   static const char * const Table[] = {
    426     "not_intrinsic",
    427 #define GET_INTRINSIC_NAME_TABLE
    428 #include "llvm/IR/Intrinsics.gen"
    429 #undef GET_INTRINSIC_NAME_TABLE
    430   };
    431   if (Tys.empty())
    432     return Table[id];
    433   std::string Result(Table[id]);
    434   for (unsigned i = 0; i < Tys.size(); ++i) {
    435     if (PointerType* PTyp = dyn_cast<PointerType>(Tys[i])) {
    436       Result += ".p" + llvm::utostr(PTyp->getAddressSpace()) +
    437                 EVT::getEVT(PTyp->getElementType()).getEVTString();
    438     }
    439     else if (Tys[i])
    440       Result += "." + EVT::getEVT(Tys[i]).getEVTString();
    441   }
    442   return Result;
    443 }
    444 
    445 
    446 /// IIT_Info - These are enumerators that describe the entries returned by the
    447 /// getIntrinsicInfoTableEntries function.
    448 ///
    449 /// NOTE: This must be kept in synch with the copy in TblGen/IntrinsicEmitter!
    450 enum IIT_Info {
    451   // Common values should be encoded with 0-15.
    452   IIT_Done = 0,
    453   IIT_I1   = 1,
    454   IIT_I8   = 2,
    455   IIT_I16  = 3,
    456   IIT_I32  = 4,
    457   IIT_I64  = 5,
    458   IIT_F16  = 6,
    459   IIT_F32  = 7,
    460   IIT_F64  = 8,
    461   IIT_V2   = 9,
    462   IIT_V4   = 10,
    463   IIT_V8   = 11,
    464   IIT_V16  = 12,
    465   IIT_V32  = 13,
    466   IIT_PTR  = 14,
    467   IIT_ARG  = 15,
    468 
    469   // Values from 16+ are only encodable with the inefficient encoding.
    470   IIT_MMX  = 16,
    471   IIT_METADATA = 17,
    472   IIT_EMPTYSTRUCT = 18,
    473   IIT_STRUCT2 = 19,
    474   IIT_STRUCT3 = 20,
    475   IIT_STRUCT4 = 21,
    476   IIT_STRUCT5 = 22,
    477   IIT_EXTEND_ARG = 23,
    478   IIT_TRUNC_ARG = 24,
    479   IIT_ANYPTR = 25,
    480   IIT_V1   = 26,
    481   IIT_VARARG = 27,
    482   IIT_HALF_VEC_ARG = 28
    483 };
    484 
    485 
    486 static void DecodeIITType(unsigned &NextElt, ArrayRef<unsigned char> Infos,
    487                       SmallVectorImpl<Intrinsic::IITDescriptor> &OutputTable) {
    488   IIT_Info Info = IIT_Info(Infos[NextElt++]);
    489   unsigned StructElts = 2;
    490   using namespace Intrinsic;
    491 
    492   switch (Info) {
    493   case IIT_Done:
    494     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Void, 0));
    495     return;
    496   case IIT_VARARG:
    497     OutputTable.push_back(IITDescriptor::get(IITDescriptor::VarArg, 0));
    498     return;
    499   case IIT_MMX:
    500     OutputTable.push_back(IITDescriptor::get(IITDescriptor::MMX, 0));
    501     return;
    502   case IIT_METADATA:
    503     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Metadata, 0));
    504     return;
    505   case IIT_F16:
    506     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Half, 0));
    507     return;
    508   case IIT_F32:
    509     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Float, 0));
    510     return;
    511   case IIT_F64:
    512     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Double, 0));
    513     return;
    514   case IIT_I1:
    515     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 1));
    516     return;
    517   case IIT_I8:
    518     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 8));
    519     return;
    520   case IIT_I16:
    521     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer,16));
    522     return;
    523   case IIT_I32:
    524     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 32));
    525     return;
    526   case IIT_I64:
    527     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Integer, 64));
    528     return;
    529   case IIT_V1:
    530     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 1));
    531     DecodeIITType(NextElt, Infos, OutputTable);
    532     return;
    533   case IIT_V2:
    534     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 2));
    535     DecodeIITType(NextElt, Infos, OutputTable);
    536     return;
    537   case IIT_V4:
    538     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 4));
    539     DecodeIITType(NextElt, Infos, OutputTable);
    540     return;
    541   case IIT_V8:
    542     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 8));
    543     DecodeIITType(NextElt, Infos, OutputTable);
    544     return;
    545   case IIT_V16:
    546     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 16));
    547     DecodeIITType(NextElt, Infos, OutputTable);
    548     return;
    549   case IIT_V32:
    550     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Vector, 32));
    551     DecodeIITType(NextElt, Infos, OutputTable);
    552     return;
    553   case IIT_PTR:
    554     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Pointer, 0));
    555     DecodeIITType(NextElt, Infos, OutputTable);
    556     return;
    557   case IIT_ANYPTR: {  // [ANYPTR addrspace, subtype]
    558     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Pointer,
    559                                              Infos[NextElt++]));
    560     DecodeIITType(NextElt, Infos, OutputTable);
    561     return;
    562   }
    563   case IIT_ARG: {
    564     unsigned ArgInfo = (NextElt == Infos.size() ? 0 : Infos[NextElt++]);
    565     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Argument, ArgInfo));
    566     return;
    567   }
    568   case IIT_EXTEND_ARG: {
    569     unsigned ArgInfo = (NextElt == Infos.size() ? 0 : Infos[NextElt++]);
    570     OutputTable.push_back(IITDescriptor::get(IITDescriptor::ExtendArgument,
    571                                              ArgInfo));
    572     return;
    573   }
    574   case IIT_TRUNC_ARG: {
    575     unsigned ArgInfo = (NextElt == Infos.size() ? 0 : Infos[NextElt++]);
    576     OutputTable.push_back(IITDescriptor::get(IITDescriptor::TruncArgument,
    577                                              ArgInfo));
    578     return;
    579   }
    580   case IIT_HALF_VEC_ARG: {
    581     unsigned ArgInfo = (NextElt == Infos.size() ? 0 : Infos[NextElt++]);
    582     OutputTable.push_back(IITDescriptor::get(IITDescriptor::HalfVecArgument,
    583                                              ArgInfo));
    584     return;
    585   }
    586   case IIT_EMPTYSTRUCT:
    587     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Struct, 0));
    588     return;
    589   case IIT_STRUCT5: ++StructElts; // FALL THROUGH.
    590   case IIT_STRUCT4: ++StructElts; // FALL THROUGH.
    591   case IIT_STRUCT3: ++StructElts; // FALL THROUGH.
    592   case IIT_STRUCT2: {
    593     OutputTable.push_back(IITDescriptor::get(IITDescriptor::Struct,StructElts));
    594 
    595     for (unsigned i = 0; i != StructElts; ++i)
    596       DecodeIITType(NextElt, Infos, OutputTable);
    597     return;
    598   }
    599   }
    600   llvm_unreachable("unhandled");
    601 }
    602 
    603 
    604 #define GET_INTRINSIC_GENERATOR_GLOBAL
    605 #include "llvm/IR/Intrinsics.gen"
    606 #undef GET_INTRINSIC_GENERATOR_GLOBAL
    607 
    608 void Intrinsic::getIntrinsicInfoTableEntries(ID id,
    609                                              SmallVectorImpl<IITDescriptor> &T){
    610   // Check to see if the intrinsic's type was expressible by the table.
    611   unsigned TableVal = IIT_Table[id-1];
    612 
    613   // Decode the TableVal into an array of IITValues.
    614   SmallVector<unsigned char, 8> IITValues;
    615   ArrayRef<unsigned char> IITEntries;
    616   unsigned NextElt = 0;
    617   if ((TableVal >> 31) != 0) {
    618     // This is an offset into the IIT_LongEncodingTable.
    619     IITEntries = IIT_LongEncodingTable;
    620 
    621     // Strip sentinel bit.
    622     NextElt = (TableVal << 1) >> 1;
    623   } else {
    624     // Decode the TableVal into an array of IITValues.  If the entry was encoded
    625     // into a single word in the table itself, decode it now.
    626     do {
    627       IITValues.push_back(TableVal & 0xF);
    628       TableVal >>= 4;
    629     } while (TableVal);
    630 
    631     IITEntries = IITValues;
    632     NextElt = 0;
    633   }
    634 
    635   // Okay, decode the table into the output vector of IITDescriptors.
    636   DecodeIITType(NextElt, IITEntries, T);
    637   while (NextElt != IITEntries.size() && IITEntries[NextElt] != 0)
    638     DecodeIITType(NextElt, IITEntries, T);
    639 }
    640 
    641 
    642 static Type *DecodeFixedType(ArrayRef<Intrinsic::IITDescriptor> &Infos,
    643                              ArrayRef<Type*> Tys, LLVMContext &Context) {
    644   using namespace Intrinsic;
    645   IITDescriptor D = Infos.front();
    646   Infos = Infos.slice(1);
    647 
    648   switch (D.Kind) {
    649   case IITDescriptor::Void: return Type::getVoidTy(Context);
    650   case IITDescriptor::VarArg: return Type::getVoidTy(Context);
    651   case IITDescriptor::MMX: return Type::getX86_MMXTy(Context);
    652   case IITDescriptor::Metadata: return Type::getMetadataTy(Context);
    653   case IITDescriptor::Half: return Type::getHalfTy(Context);
    654   case IITDescriptor::Float: return Type::getFloatTy(Context);
    655   case IITDescriptor::Double: return Type::getDoubleTy(Context);
    656 
    657   case IITDescriptor::Integer:
    658     return IntegerType::get(Context, D.Integer_Width);
    659   case IITDescriptor::Vector:
    660     return VectorType::get(DecodeFixedType(Infos, Tys, Context),D.Vector_Width);
    661   case IITDescriptor::Pointer:
    662     return PointerType::get(DecodeFixedType(Infos, Tys, Context),
    663                             D.Pointer_AddressSpace);
    664   case IITDescriptor::Struct: {
    665     Type *Elts[5];
    666     assert(D.Struct_NumElements <= 5 && "Can't handle this yet");
    667     for (unsigned i = 0, e = D.Struct_NumElements; i != e; ++i)
    668       Elts[i] = DecodeFixedType(Infos, Tys, Context);
    669     return StructType::get(Context, ArrayRef<Type*>(Elts,D.Struct_NumElements));
    670   }
    671 
    672   case IITDescriptor::Argument:
    673     return Tys[D.getArgumentNumber()];
    674   case IITDescriptor::ExtendArgument: {
    675     Type *Ty = Tys[D.getArgumentNumber()];
    676     if (VectorType *VTy = dyn_cast<VectorType>(Ty))
    677       return VectorType::getExtendedElementVectorType(VTy);
    678 
    679     return IntegerType::get(Context, 2 * cast<IntegerType>(Ty)->getBitWidth());
    680   }
    681   case IITDescriptor::TruncArgument: {
    682     Type *Ty = Tys[D.getArgumentNumber()];
    683     if (VectorType *VTy = dyn_cast<VectorType>(Ty))
    684       return VectorType::getTruncatedElementVectorType(VTy);
    685 
    686     IntegerType *ITy = cast<IntegerType>(Ty);
    687     assert(ITy->getBitWidth() % 2 == 0);
    688     return IntegerType::get(Context, ITy->getBitWidth() / 2);
    689   }
    690   case IITDescriptor::HalfVecArgument:
    691     return VectorType::getHalfElementsVectorType(cast<VectorType>(
    692                                                   Tys[D.getArgumentNumber()]));
    693   }
    694   llvm_unreachable("unhandled");
    695 }
    696 
    697 
    698 
    699 FunctionType *Intrinsic::getType(LLVMContext &Context,
    700                                  ID id, ArrayRef<Type*> Tys) {
    701   SmallVector<IITDescriptor, 8> Table;
    702   getIntrinsicInfoTableEntries(id, Table);
    703 
    704   ArrayRef<IITDescriptor> TableRef = Table;
    705   Type *ResultTy = DecodeFixedType(TableRef, Tys, Context);
    706 
    707   SmallVector<Type*, 8> ArgTys;
    708   while (!TableRef.empty())
    709     ArgTys.push_back(DecodeFixedType(TableRef, Tys, Context));
    710 
    711   return FunctionType::get(ResultTy, ArgTys, false);
    712 }
    713 
    714 bool Intrinsic::isOverloaded(ID id) {
    715 #define GET_INTRINSIC_OVERLOAD_TABLE
    716 #include "llvm/IR/Intrinsics.gen"
    717 #undef GET_INTRINSIC_OVERLOAD_TABLE
    718 }
    719 
    720 /// This defines the "Intrinsic::getAttributes(ID id)" method.
    721 #define GET_INTRINSIC_ATTRIBUTES
    722 #include "llvm/IR/Intrinsics.gen"
    723 #undef GET_INTRINSIC_ATTRIBUTES
    724 
    725 Function *Intrinsic::getDeclaration(Module *M, ID id, ArrayRef<Type*> Tys) {
    726   // There can never be multiple globals with the same name of different types,
    727   // because intrinsics must be a specific type.
    728   return
    729     cast<Function>(M->getOrInsertFunction(getName(id, Tys),
    730                                           getType(M->getContext(), id, Tys)));
    731 }
    732 
    733 // This defines the "Intrinsic::getIntrinsicForGCCBuiltin()" method.
    734 #define GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
    735 #include "llvm/IR/Intrinsics.gen"
    736 #undef GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
    737 
    738 // This defines the "Intrinsic::getIntrinsicForMSBuiltin()" method.
    739 #define GET_LLVM_INTRINSIC_FOR_MS_BUILTIN
    740 #include "llvm/IR/Intrinsics.gen"
    741 #undef GET_LLVM_INTRINSIC_FOR_MS_BUILTIN
    742 
    743 /// hasAddressTaken - returns true if there are any uses of this function
    744 /// other than direct calls or invokes to it.
    745 bool Function::hasAddressTaken(const User* *PutOffender) const {
    746   for (const Use &U : uses()) {
    747     const User *FU = U.getUser();
    748     if (isa<BlockAddress>(FU))
    749       continue;
    750     if (!isa<CallInst>(FU) && !isa<InvokeInst>(FU))
    751       return PutOffender ? (*PutOffender = FU, true) : true;
    752     ImmutableCallSite CS(cast<Instruction>(FU));
    753     if (!CS.isCallee(&U))
    754       return PutOffender ? (*PutOffender = FU, true) : true;
    755   }
    756   return false;
    757 }
    758 
    759 bool Function::isDefTriviallyDead() const {
    760   // Check the linkage
    761   if (!hasLinkOnceLinkage() && !hasLocalLinkage() &&
    762       !hasAvailableExternallyLinkage())
    763     return false;
    764 
    765   // Check if the function is used by anything other than a blockaddress.
    766   for (const User *U : users())
    767     if (!isa<BlockAddress>(U))
    768       return false;
    769 
    770   return true;
    771 }
    772 
    773 /// callsFunctionThatReturnsTwice - Return true if the function has a call to
    774 /// setjmp or other function that gcc recognizes as "returning twice".
    775 bool Function::callsFunctionThatReturnsTwice() const {
    776   for (const_inst_iterator
    777          I = inst_begin(this), E = inst_end(this); I != E; ++I) {
    778     ImmutableCallSite CS(&*I);
    779     if (CS && CS.hasFnAttr(Attribute::ReturnsTwice))
    780       return true;
    781   }
    782 
    783   return false;
    784 }
    785 
    786 Constant *Function::getPrefixData() const {
    787   assert(hasPrefixData());
    788   const LLVMContextImpl::PrefixDataMapTy &PDMap =
    789       getContext().pImpl->PrefixDataMap;
    790   assert(PDMap.find(this) != PDMap.end());
    791   return cast<Constant>(PDMap.find(this)->second->getReturnValue());
    792 }
    793 
    794 void Function::setPrefixData(Constant *PrefixData) {
    795   if (!PrefixData && !hasPrefixData())
    796     return;
    797 
    798   unsigned SCData = getSubclassDataFromValue();
    799   LLVMContextImpl::PrefixDataMapTy &PDMap = getContext().pImpl->PrefixDataMap;
    800   ReturnInst *&PDHolder = PDMap[this];
    801   if (PrefixData) {
    802     if (PDHolder)
    803       PDHolder->setOperand(0, PrefixData);
    804     else
    805       PDHolder = ReturnInst::Create(getContext(), PrefixData);
    806     SCData |= 2;
    807   } else {
    808     delete PDHolder;
    809     PDMap.erase(this);
    810     SCData &= ~2;
    811   }
    812   setValueSubclassData(SCData);
    813 }
    814