lib/VMCore/Function.cpp

   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/LeakDetector.h"
  21 #include "llvm/Support/ManagedStatic.h"
  22 #include "llvm/Support/StringPool.h"
  23 #include "llvm/Support/RWMutex.h"
  24 #include "llvm/Support/Threading.h"
  25 #include "SymbolTableListTraitsImpl.h"
  26 #include "llvm/ADT/DenseMap.h"
  27 #include "llvm/ADT/STLExtras.h"
  28 #include "llvm/ADT/StringExtras.h"
  29 using namespace llvm;
  30
  31
  32 // Explicit instantiations of SymbolTableListTraits since some of the methods
  33 // are not in the public header file...
  34 template class llvm::SymbolTableListTraits<Argument, Function>;
  35 template class llvm::SymbolTableListTraits<BasicBlock, Function>;
  36
  37 //===----------------------------------------------------------------------===//
  38 // Argument Implementation
  39 //===----------------------------------------------------------------------===//
  40
  41 Argument::Argument(const Type *Ty, const Twine &Name, Function *Par)
  42   : Value(Ty, Value::ArgumentVal) {
  43   Parent = 0;
  44
  45   // Make sure that we get added to a function
  46   LeakDetector::addGarbageObject(this);
  47
  48   if (Par)
  49     Par->getArgumentList().push_back(this);
  50   setName(Name);
  51 }
  52
  53 void Argument::setParent(Function *parent) {
  54   if (getParent())
  55     LeakDetector::addGarbageObject(this);
  56   Parent = parent;
  57   if (getParent())
  58     LeakDetector::removeGarbageObject(this);
  59 }
  60
  61 /// getArgNo - Return the index of this formal argument in its containing
  62 /// function.  For example in "void foo(int a, float b)" a is 0 and b is 1.
  63 unsigned Argument::getArgNo() const {
  64   const Function *F = getParent();
  65   assert(F && "Argument is not in a function");
  66
  67   Function::const_arg_iterator AI = F->arg_begin();
  68   unsigned ArgIdx = 0;
  69   for (; &*AI != this; ++AI)
  70     ++ArgIdx;
  71
  72   return ArgIdx;
  73 }
  74
  75 /// hasByValAttr - Return true if this argument has the byval attribute on it
  76 /// in its containing function.
  77 bool Argument::hasByValAttr() const {
  78   if (!getType()->isPointerTy()) return false;
  79   return getParent()->paramHasAttr(getArgNo()+1, Attribute::ByVal);
  80 }
  81
  82 unsigned Argument::getParamAlignment() const {
  83   assert(getType()->isPointerTy() && "Only pointers have alignments");
  84   return getParent()->getParamAlignment(getArgNo()+1);
  85
  86 }
  87
  88 /// hasNestAttr - Return true if this argument has the nest attribute on
  89 /// it in its containing function.
  90 bool Argument::hasNestAttr() const {
  91   if (!getType()->isPointerTy()) return false;
  92   return getParent()->paramHasAttr(getArgNo()+1, Attribute::Nest);
  93 }
  94
  95 /// hasNoAliasAttr - Return true if this argument has the noalias attribute on
  96 /// it in its containing function.
  97 bool Argument::hasNoAliasAttr() const {
  98   if (!getType()->isPointerTy()) return false;
  99   return getParent()->paramHasAttr(getArgNo()+1, Attribute::NoAlias);
 100 }
 101
 102 /// hasNoCaptureAttr - Return true if this argument has the nocapture attribute
 103 /// on it in its containing function.
 104 bool Argument::hasNoCaptureAttr() const {
 105   if (!getType()->isPointerTy()) return false;
 106   return getParent()->paramHasAttr(getArgNo()+1, Attribute::NoCapture);
 107 }
 108
 109 /// hasSRetAttr - Return true if this argument has the sret attribute on
 110 /// it in its containing function.
 111 bool Argument::hasStructRetAttr() const {
 112   if (!getType()->isPointerTy()) return false;
 113   if (this != getParent()->arg_begin())
 114     return false; // StructRet param must be first param
 115   return getParent()->paramHasAttr(1, Attribute::StructRet);
 116 }
 117
 118 /// addAttr - Add a Attribute to an argument
 119 void Argument::addAttr(Attributes attr) {
 120   getParent()->addAttribute(getArgNo() + 1, attr);
 121 }
 122
 123 /// removeAttr - Remove a Attribute from an argument
 124 void Argument::removeAttr(Attributes attr) {
 125   getParent()->removeAttribute(getArgNo() + 1, attr);
 126 }
 127
 128
 129 //===----------------------------------------------------------------------===//
 130 // Helper Methods in Function
 131 //===----------------------------------------------------------------------===//
 132
 133 LLVMContext &Function::getContext() const {
 134   return getType()->getContext();
 135 }
 136
 137 FunctionType *Function::getFunctionType() const {
 138   return cast<FunctionType>(getType()->getElementType());
 139 }
 140
 141 bool Function::isVarArg() const {
 142   return getFunctionType()->isVarArg();
 143 }
 144
 145 Type *Function::getReturnType() const {
 146   return getFunctionType()->getReturnType();
 147 }
 148
 149 void Function::removeFromParent() {
 150   getParent()->getFunctionList().remove(this);
 151 }
 152
 153 void Function::eraseFromParent() {
 154   getParent()->getFunctionList().erase(this);
 155 }
 156
 157 //===----------------------------------------------------------------------===//
 158 // Function Implementation
 159 //===----------------------------------------------------------------------===//
 160
 161 Function::Function(const FunctionType *Ty, LinkageTypes Linkage,
 162                    const Twine &name, Module *ParentModule)
 163   : GlobalValue(PointerType::getUnqual(Ty),
 164                 Value::FunctionVal, 0, 0, Linkage, name) {
 165   assert(FunctionType::isValidReturnType(getReturnType()) &&
 166          "invalid return type");
 167   SymTab = new ValueSymbolTable();
 168
 169   // If the function has arguments, mark them as lazily built.
 170   if (Ty->getNumParams())
 171     setValueSubclassData(1);   // Set the "has lazy arguments" bit.
 172
 173   // Make sure that we get added to a function
 174   LeakDetector::addGarbageObject(this);
 175
 176   if (ParentModule)
 177     ParentModule->getFunctionList().push_back(this);
 178
 179   // Ensure intrinsics have the right parameter attributes.
 180   if (unsigned IID = getIntrinsicID())
 181     setAttributes(Intrinsic::getAttributes(Intrinsic::ID(IID)));
 182
 183 }
 184
 185 Function::~Function() {
 186   dropAllReferences();    // After this it is safe to delete instructions.
 187
 188   // Delete all of the method arguments and unlink from symbol table...
 189   ArgumentList.clear();
 190   delete SymTab;
 191
 192   // Remove the function from the on-the-side GC table.
 193   clearGC();
 194 }
 195
 196 void Function::BuildLazyArguments() const {
 197   // Create the arguments vector, all arguments start out unnamed.
 198   const FunctionType *FT = getFunctionType();
 199   for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
 200     assert(!FT->getParamType(i)->isVoidTy() &&
 201            "Cannot have void typed arguments!");
 202     ArgumentList.push_back(new Argument(FT->getParamType(i)));
 203   }
 204
 205   // Clear the lazy arguments bit.
 206   unsigned SDC = getSubclassDataFromValue();
 207   const_cast<Function*>(this)->setValueSubclassData(SDC &= ~1);
 208 }
 209
 210 size_t Function::arg_size() const {
 211   return getFunctionType()->getNumParams();
 212 }
 213 bool Function::arg_empty() const {
 214   return getFunctionType()->getNumParams() == 0;
 215 }
 216
 217 void Function::setParent(Module *parent) {
 218   if (getParent())
 219     LeakDetector::addGarbageObject(this);
 220   Parent = parent;
 221   if (getParent())
 222     LeakDetector::removeGarbageObject(this);
 223 }
 224
 225 // dropAllReferences() - This function causes all the subinstructions to "let
 226 // go" of all references that they are maintaining.  This allows one to
 227 // 'delete' a whole class at a time, even though there may be circular
 228 // references... first all references are dropped, and all use counts go to
 229 // zero.  Then everything is deleted for real.  Note that no operations are
 230 // valid on an object that has "dropped all references", except operator
 231 // delete.
 232 //
 233 void Function::dropAllReferences() {
 234   for (iterator I = begin(), E = end(); I != E; ++I)
 235     I->dropAllReferences();
 236
 237   // Delete all basic blocks. They are now unused, except possibly by
 238   // blockaddresses, but BasicBlock's destructor takes care of those.
 239   while (!BasicBlocks.empty())
 240     BasicBlocks.begin()->eraseFromParent();
 241 }
 242
 243 void Function::addAttribute(unsigned i, Attributes attr) {
 244   AttrListPtr PAL = getAttributes();
 245   PAL = PAL.addAttr(i, attr);
 246   setAttributes(PAL);
 247 }
 248
 249 void Function::removeAttribute(unsigned i, Attributes attr) {
 250   AttrListPtr PAL = getAttributes();
 251   PAL = PAL.removeAttr(i, attr);
 252   setAttributes(PAL);
 253 }
 254
 255 // Maintain the GC name for each function in an on-the-side table. This saves
 256 // allocating an additional word in Function for programs which do not use GC
 257 // (i.e., most programs) at the cost of increased overhead for clients which do
 258 // use GC.
 259 static DenseMap<const Function*,PooledStringPtr> *GCNames;
 260 static StringPool *GCNamePool;
 261 static ManagedStatic<sys::SmartRWMutex<true> > GCLock;
 262
 263 bool Function::hasGC() const {
 264   sys::SmartScopedReader<true> Reader(*GCLock);
 265   return GCNames && GCNames->count(this);
 266 }
 267
 268 const char *Function::getGC() const {
 269   assert(hasGC() && "Function has no collector");
 270   sys::SmartScopedReader<true> Reader(*GCLock);
 271   return *(*GCNames)[this];
 272 }
 273
 274 void Function::setGC(const char *Str) {
 275   sys::SmartScopedWriter<true> Writer(*GCLock);
 276   if (!GCNamePool)
 277     GCNamePool = new StringPool();
 278   if (!GCNames)
 279     GCNames = new DenseMap<const Function*,PooledStringPtr>();
 280   (*GCNames)[this] = GCNamePool->intern(Str);
 281 }
 282
 283 void Function::clearGC() {
 284   sys::SmartScopedWriter<true> Writer(*GCLock);
 285   if (GCNames) {
 286     GCNames->erase(this);
 287     if (GCNames->empty()) {
 288       delete GCNames;
 289       GCNames = 0;
 290       if (GCNamePool->empty()) {
 291         delete GCNamePool;
 292         GCNamePool = 0;
 293       }
 294     }
 295   }
 296 }
 297
 298 /// copyAttributesFrom - copy all additional attributes (those not needed to
 299 /// create a Function) from the Function Src to this one.
 300 void Function::copyAttributesFrom(const GlobalValue *Src) {
 301   assert(isa<Function>(Src) && "Expected a Function!");
 302   GlobalValue::copyAttributesFrom(Src);
 303   const Function *SrcF = cast<Function>(Src);
 304   setCallingConv(SrcF->getCallingConv());
 305   setAttributes(SrcF->getAttributes());
 306   if (SrcF->hasGC())
 307     setGC(SrcF->getGC());
 308   else
 309     clearGC();
 310 }
 311
 312 /// getIntrinsicID - This method returns the ID number of the specified
 313 /// function, or Intrinsic::not_intrinsic if the function is not an
 314 /// intrinsic, or if the pointer is null.  This value is always defined to be
 315 /// zero to allow easy checking for whether a function is intrinsic or not.  The
 316 /// particular intrinsic functions which correspond to this value are defined in
 317 /// llvm/Intrinsics.h.
 318 ///
 319 unsigned Function::getIntrinsicID() const {
 320   const ValueName *ValName = this->getValueName();
 321   if (!ValName)
 322     return 0;
 323   unsigned Len = ValName->getKeyLength();
 324   const char *Name = ValName->getKeyData();
 325
 326   if (Len < 5 || Name[4] != '.' || Name[0] != 'l' || Name[1] != 'l'
 327       || Name[2] != 'v' || Name[3] != 'm')
 328     return 0;  // All intrinsics start with 'llvm.'
 329
 330 #define GET_FUNCTION_RECOGNIZER
 331 #include "llvm/Intrinsics.gen"
 332 #undef GET_FUNCTION_RECOGNIZER
 333   return 0;
 334 }
 335
 336 std::string Intrinsic::getName(ID id, const Type **Tys, unsigned numTys) {
 337   assert(id < num_intrinsics && "Invalid intrinsic ID!");
 338   static const char * const Table[] = {
 339     "not_intrinsic",
 340 #define GET_INTRINSIC_NAME_TABLE
 341 #include "llvm/Intrinsics.gen"
 342 #undef GET_INTRINSIC_NAME_TABLE
 343   };
 344   if (numTys == 0)
 345     return Table[id];
 346   std::string Result(Table[id]);
 347   for (unsigned i = 0; i < numTys; ++i) {
 348     if (const PointerType* PTyp = dyn_cast<PointerType>(Tys[i])) {
 349       Result += ".p" + llvm::utostr(PTyp->getAddressSpace()) +
 350                 EVT::getEVT(PTyp->getElementType()).getEVTString();
 351     }
 352     else if (Tys[i])
 353       Result += "." + EVT::getEVT(Tys[i]).getEVTString();
 354   }
 355   return Result;
 356 }
 357
 358 const FunctionType *Intrinsic::getType(LLVMContext &Context,
 359                                        ID id, const Type **Tys,
 360                                        unsigned numTys) {
 361   const Type *ResultTy = NULL;
 362   std::vector<const Type*> ArgTys;
 363   bool IsVarArg = false;
 364
 365 #define GET_INTRINSIC_GENERATOR
 366 #include "llvm/Intrinsics.gen"
 367 #undef GET_INTRINSIC_GENERATOR
 368
 369   return FunctionType::get(ResultTy, ArgTys, IsVarArg);
 370 }
 371
 372 bool Intrinsic::isOverloaded(ID id) {
 373   static const bool OTable[] = {
 374     false,
 375 #define GET_INTRINSIC_OVERLOAD_TABLE
 376 #include "llvm/Intrinsics.gen"
 377 #undef GET_INTRINSIC_OVERLOAD_TABLE
 378   };
 379   return OTable[id];
 380 }
 381
 382 /// This defines the "Intrinsic::getAttributes(ID id)" method.
 383 #define GET_INTRINSIC_ATTRIBUTES
 384 #include "llvm/Intrinsics.gen"
 385 #undef GET_INTRINSIC_ATTRIBUTES
 386
 387 Function *Intrinsic::getDeclaration(Module *M, ID id, const Type **Tys,
 388                                     unsigned numTys) {
 389   // There can never be multiple globals with the same name of different types,
 390   // because intrinsics must be a specific type.
 391   return
 392     cast<Function>(M->getOrInsertFunction(getName(id, Tys, numTys),
 393                                           getType(M->getContext(),
 394                                                   id, Tys, numTys)));
 395 }
 396
 397 // This defines the "Intrinsic::getIntrinsicForGCCBuiltin()" method.
 398 #define GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
 399 #include "llvm/Intrinsics.gen"
 400 #undef GET_LLVM_INTRINSIC_FOR_GCC_BUILTIN
 401
 402 /// hasAddressTaken - returns true if there are any uses of this function
 403 /// other than direct calls or invokes to it.
 404 bool Function::hasAddressTaken(const User* *PutOffender) const {
 405   for (Value::const_use_iterator I = use_begin(), E = use_end(); I != E; ++I) {
 406     const User *U = *I;
 407     if (!isa<CallInst>(U) && !isa<InvokeInst>(U))
 408       return PutOffender ? (*PutOffender = U, true) : true;
 409     ImmutableCallSite CS(cast<Instruction>(U));
 410     if (!CS.isCallee(I))
 411       return PutOffender ? (*PutOffender = U, true) : true;
 412   }
 413   return false;
 414 }
 415
 416 /// callsFunctionThatReturnsTwice - Return true if the function has a call to
 417 /// setjmp or other function that gcc recognizes as "returning twice".
 418 ///
 419 /// FIXME: Remove after <rdar://problem/8031714> is fixed.
 420 /// FIXME: Is the above FIXME valid?
 421 bool Function::callsFunctionThatReturnsTwice() const {
 422   const Module *M = this->getParent();
 423   static const char *ReturnsTwiceFns[] = {
 424     "_setjmp",
 425     "setjmp",
 426     "sigsetjmp",
 427     "setjmp_syscall",
 428     "savectx",
 429     "qsetjmp",
 430     "vfork",
 431     "getcontext"
 432   };
 433
 434   for (unsigned I = 0; I < array_lengthof(ReturnsTwiceFns); ++I)
 435     if (const Function *Callee = M->getFunction(ReturnsTwiceFns[I])) {
 436       if (!Callee->use_empty())
 437         for (Value::const_use_iterator
 438                I = Callee->use_begin(), E = Callee->use_end();
 439              I != E; ++I)
 440           if (const CallInst *CI = dyn_cast<CallInst>(*I))
 441             if (CI->getParent()->getParent() == this)
 442               return true;
 443     }
 444
 445   return false;
 446 }
 447
 448 // vim: sw=2 ai