src/llvm/include/llvm/IR/Function.h

   1 //===-- llvm/Function.h - Class to represent a single function --*- C++ -*-===//
   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 contains the declaration of the Function class, which represents a
  11 // single function/procedure in LLVM.
  12 //
  13 // A function basically consists of a list of basic blocks, a list of arguments,
  14 // and a symbol table.
  15 //
  16 //===----------------------------------------------------------------------===//
  17
  18 #ifndef LLVM_IR_FUNCTION_H
  19 #define LLVM_IR_FUNCTION_H
  20
  21 #include "llvm/ADT/iterator_range.h"
  22 #include "llvm/IR/Argument.h"
  23 #include "llvm/IR/Attributes.h"
  24 #include "llvm/IR/BasicBlock.h"
  25 #include "llvm/IR/CallingConv.h"
  26 #include "llvm/IR/GlobalObject.h"
  27 #include "llvm/Support/Compiler.h"
  28
  29 namespace llvm {
  30
  31 class FunctionType;
  32 class LLVMContext;
  33
  34 // Traits for intrusive list of basic blocks...
  35 template<> struct ilist_traits<BasicBlock>
  36   : public SymbolTableListTraits<BasicBlock, Function> {
  37
  38   // createSentinel is used to get hold of the node that marks the end of the
  39   // list... (same trick used here as in ilist_traits<Instruction>)
  40   BasicBlock *createSentinel() const {
  41     return static_cast<BasicBlock*>(&Sentinel);
  42   }
  43   static void destroySentinel(BasicBlock*) {}
  44
  45   BasicBlock *provideInitialHead() const { return createSentinel(); }
  46   BasicBlock *ensureHead(BasicBlock*) const { return createSentinel(); }
  47   static void noteHead(BasicBlock*, BasicBlock*) {}
  48
  49   static ValueSymbolTable *getSymTab(Function *ItemParent);
  50 private:
  51   mutable ilist_half_node<BasicBlock> Sentinel;
  52 };
  53
  54 template<> struct ilist_traits<Argument>
  55   : public SymbolTableListTraits<Argument, Function> {
  56
  57   Argument *createSentinel() const {
  58     return static_cast<Argument*>(&Sentinel);
  59   }
  60   static void destroySentinel(Argument*) {}
  61
  62   Argument *provideInitialHead() const { return createSentinel(); }
  63   Argument *ensureHead(Argument*) const { return createSentinel(); }
  64   static void noteHead(Argument*, Argument*) {}
  65
  66   static ValueSymbolTable *getSymTab(Function *ItemParent);
  67 private:
  68   mutable ilist_half_node<Argument> Sentinel;
  69 };
  70
  71 class Function : public GlobalObject, public ilist_node<Function> {
  72 public:
  73   typedef iplist<Argument> ArgumentListType;
  74   typedef iplist<BasicBlock> BasicBlockListType;
  75
  76   // BasicBlock iterators...
  77   typedef BasicBlockListType::iterator iterator;
  78   typedef BasicBlockListType::const_iterator const_iterator;
  79
  80   typedef ArgumentListType::iterator arg_iterator;
  81   typedef ArgumentListType::const_iterator const_arg_iterator;
  82
  83 private:
  84   // Important things that make up a function!
  85   BasicBlockListType  BasicBlocks;        ///< The basic blocks
  86   mutable ArgumentListType ArgumentList;  ///< The formal arguments
  87   ValueSymbolTable *SymTab;               ///< Symbol table of args/instructions
  88   AttributeSet AttributeSets;             ///< Parameter attributes
  89
  90   /*
  91    * Value::SubclassData
  92    *
  93    * bit 0  : HasLazyArguments
  94    * bit 1  : HasPrefixData
  95    * bit 2  : HasPrologueData
  96    * bit 3-6: CallingConvention
  97    */
  98
  99   friend class SymbolTableListTraits<Function, Module>;
 100
 101   void setParent(Module *parent);
 102
 103   /// hasLazyArguments/CheckLazyArguments - The argument list of a function is
 104   /// built on demand, so that the list isn't allocated until the first client
 105   /// needs it.  The hasLazyArguments predicate returns true if the arg list
 106   /// hasn't been set up yet.
 107   bool hasLazyArguments() const {
 108     return getSubclassDataFromValue() & (1<<0);
 109   }
 110   void CheckLazyArguments() const {
 111     if (hasLazyArguments())
 112       BuildLazyArguments();
 113   }
 114   void BuildLazyArguments() const;
 115
 116   Function(const Function&) LLVM_DELETED_FUNCTION;
 117   void operator=(const Function&) LLVM_DELETED_FUNCTION;
 118
 119   /// Do the actual lookup of an intrinsic ID when the query could not be
 120   /// answered from the cache.
 121   unsigned lookupIntrinsicID() const LLVM_READONLY;
 122
 123   /// Function ctor - If the (optional) Module argument is specified, the
 124   /// function is automatically inserted into the end of the function list for
 125   /// the module.
 126   ///
 127   Function(FunctionType *Ty, LinkageTypes Linkage,
 128            const Twine &N = "", Module *M = nullptr);
 129
 130 public:
 131   static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
 132                           const Twine &N = "", Module *M = nullptr) {
 133     return new(0) Function(Ty, Linkage, N, M);
 134   }
 135
 136   ~Function();
 137
 138   Type *getReturnType() const;           // Return the type of the ret val
 139   FunctionType *getFunctionType() const; // Return the FunctionType for me
 140
 141   /// getContext - Return a pointer to the LLVMContext associated with this
 142   /// function, or NULL if this function is not bound to a context yet.
 143   LLVMContext &getContext() const;
 144
 145   /// isVarArg - Return true if this function takes a variable number of
 146   /// arguments.
 147   bool isVarArg() const;
 148
 149   bool isMaterializable() const;
 150   void setIsMaterializable(bool V);
 151
 152   /// getIntrinsicID - This method returns the ID number of the specified
 153   /// function, or Intrinsic::not_intrinsic if the function is not an
 154   /// intrinsic, or if the pointer is null.  This value is always defined to be
 155   /// zero to allow easy checking for whether a function is intrinsic or not.
 156   /// The particular intrinsic functions which correspond to this value are
 157   /// defined in llvm/Intrinsics.h.  Results are cached in the LLVM context,
 158   /// subsequent requests for the same ID return results much faster from the
 159   /// cache.
 160   ///
 161   unsigned getIntrinsicID() const LLVM_READONLY;
 162   bool isIntrinsic() const { return getName().startswith("llvm."); }
 163
 164   /// getCallingConv()/setCallingConv(CC) - These method get and set the
 165   /// calling convention of this function.  The enum values for the known
 166   /// calling conventions are defined in CallingConv.h.
 167   CallingConv::ID getCallingConv() const {
 168     return static_cast<CallingConv::ID>(getSubclassDataFromValue() >> 3);
 169   }
 170   void setCallingConv(CallingConv::ID CC) {
 171     setValueSubclassData((getSubclassDataFromValue() & 7) |
 172                          (static_cast<unsigned>(CC) << 3));
 173   }
 174
 175   /// @brief Return the attribute list for this Function.
 176   AttributeSet getAttributes() const { return AttributeSets; }
 177
 178   /// @brief Set the attribute list for this Function.
 179   void setAttributes(AttributeSet attrs) { AttributeSets = attrs; }
 180
 181   /// @brief Add function attributes to this function.
 182   void addFnAttr(Attribute::AttrKind N) {
 183     setAttributes(AttributeSets.addAttribute(getContext(),
 184                                              AttributeSet::FunctionIndex, N));
 185   }
 186
 187   /// @brief Remove function attributes from this function.
 188   void removeFnAttr(Attribute::AttrKind N) {
 189     setAttributes(AttributeSets.removeAttribute(
 190         getContext(), AttributeSet::FunctionIndex, N));
 191   }
 192
 193   /// @brief Add function attributes to this function.
 194   void addFnAttr(StringRef Kind) {
 195     setAttributes(
 196       AttributeSets.addAttribute(getContext(),
 197                                  AttributeSet::FunctionIndex, Kind));
 198   }
 199   void addFnAttr(StringRef Kind, StringRef Value) {
 200     setAttributes(
 201       AttributeSets.addAttribute(getContext(),
 202                                  AttributeSet::FunctionIndex, Kind, Value));
 203   }
 204
 205   /// @brief Return true if the function has the attribute.
 206   bool hasFnAttribute(Attribute::AttrKind Kind) const {
 207     return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
 208   }
 209   bool hasFnAttribute(StringRef Kind) const {
 210     return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
 211   }
 212
 213   /// @brief Return the attribute for the given attribute kind.
 214   Attribute getFnAttribute(Attribute::AttrKind Kind) const {
 215     return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
 216   }
 217   Attribute getFnAttribute(StringRef Kind) const {
 218     return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
 219   }
 220
 221   /// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
 222   ///                             to use during code generation.
 223   bool hasGC() const;
 224   const char *getGC() const;
 225   void setGC(const char *Str);
 226   void clearGC();
 227
 228   /// @brief adds the attribute to the list of attributes.
 229   void addAttribute(unsigned i, Attribute::AttrKind attr);
 230
 231   /// @brief adds the attributes to the list of attributes.
 232   void addAttributes(unsigned i, AttributeSet attrs);
 233
 234   /// @brief removes the attributes from the list of attributes.
 235   void removeAttributes(unsigned i, AttributeSet attr);
 236
 237   /// @brief Extract the alignment for a call or parameter (0=unknown).
 238   unsigned getParamAlignment(unsigned i) const {
 239     return AttributeSets.getParamAlignment(i);
 240   }
 241
 242   /// @brief Extract the number of dereferenceable bytes for a call or
 243   /// parameter (0=unknown).
 244   uint64_t getDereferenceableBytes(unsigned i) const {
 245     return AttributeSets.getDereferenceableBytes(i);
 246   }
 247
 248   /// @brief Determine if the function does not access memory.
 249   bool doesNotAccessMemory() const {
 250     return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
 251                                       Attribute::ReadNone);
 252   }
 253   void setDoesNotAccessMemory() {
 254     addFnAttr(Attribute::ReadNone);
 255   }
 256
 257   /// @brief Determine if the function does not access or only reads memory.
 258   bool onlyReadsMemory() const {
 259     return doesNotAccessMemory() ||
 260       AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
 261                                  Attribute::ReadOnly);
 262   }
 263   void setOnlyReadsMemory() {
 264     addFnAttr(Attribute::ReadOnly);
 265   }
 266
 267   /// @brief Determine if the function cannot return.
 268   bool doesNotReturn() const {
 269     return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
 270                                       Attribute::NoReturn);
 271   }
 272   void setDoesNotReturn() {
 273     addFnAttr(Attribute::NoReturn);
 274   }
 275
 276   /// @brief Determine if the function cannot unwind.
 277   bool doesNotThrow() const {
 278     return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
 279                                       Attribute::NoUnwind);
 280   }
 281   void setDoesNotThrow() {
 282     addFnAttr(Attribute::NoUnwind);
 283   }
 284
 285   /// @brief Determine if the call cannot be duplicated.
 286   bool cannotDuplicate() const {
 287     return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
 288                                       Attribute::NoDuplicate);
 289   }
 290   void setCannotDuplicate() {
 291     addFnAttr(Attribute::NoDuplicate);
 292   }
 293
 294   /// @brief True if the ABI mandates (or the user requested) that this
 295   /// function be in a unwind table.
 296   bool hasUWTable() const {
 297     return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
 298                                       Attribute::UWTable);
 299   }
 300   void setHasUWTable() {
 301     addFnAttr(Attribute::UWTable);
 302   }
 303
 304   /// @brief True if this function needs an unwind table.
 305   bool needsUnwindTableEntry() const {
 306     return hasUWTable() || !doesNotThrow();
 307   }
 308
 309   /// @brief Determine if the function returns a structure through first
 310   /// pointer argument.
 311   bool hasStructRetAttr() const {
 312     return AttributeSets.hasAttribute(1, Attribute::StructRet) ||
 313            AttributeSets.hasAttribute(2, Attribute::StructRet);
 314   }
 315
 316   /// @brief Determine if the parameter does not alias other parameters.
 317   /// @param n The parameter to check. 1 is the first parameter, 0 is the return
 318   bool doesNotAlias(unsigned n) const {
 319     return AttributeSets.hasAttribute(n, Attribute::NoAlias);
 320   }
 321   void setDoesNotAlias(unsigned n) {
 322     addAttribute(n, Attribute::NoAlias);
 323   }
 324
 325   /// @brief Determine if the parameter can be captured.
 326   /// @param n The parameter to check. 1 is the first parameter, 0 is the return
 327   bool doesNotCapture(unsigned n) const {
 328     return AttributeSets.hasAttribute(n, Attribute::NoCapture);
 329   }
 330   void setDoesNotCapture(unsigned n) {
 331     addAttribute(n, Attribute::NoCapture);
 332   }
 333
 334   bool doesNotAccessMemory(unsigned n) const {
 335     return AttributeSets.hasAttribute(n, Attribute::ReadNone);
 336   }
 337   void setDoesNotAccessMemory(unsigned n) {
 338     addAttribute(n, Attribute::ReadNone);
 339   }
 340
 341   bool onlyReadsMemory(unsigned n) const {
 342     return doesNotAccessMemory(n) ||
 343       AttributeSets.hasAttribute(n, Attribute::ReadOnly);
 344   }
 345   void setOnlyReadsMemory(unsigned n) {
 346     addAttribute(n, Attribute::ReadOnly);
 347   }
 348
 349   /// copyAttributesFrom - copy all additional attributes (those not needed to
 350   /// create a Function) from the Function Src to this one.
 351   void copyAttributesFrom(const GlobalValue *Src) override;
 352
 353   /// deleteBody - This method deletes the body of the function, and converts
 354   /// the linkage to external.
 355   ///
 356   void deleteBody() {
 357     dropAllReferences();
 358     setLinkage(ExternalLinkage);
 359   }
 360
 361   /// removeFromParent - This method unlinks 'this' from the containing module,
 362   /// but does not delete it.
 363   ///
 364   void removeFromParent() override;
 365
 366   /// eraseFromParent - This method unlinks 'this' from the containing module
 367   /// and deletes it.
 368   ///
 369   void eraseFromParent() override;
 370
 371
 372   /// Get the underlying elements of the Function... the basic block list is
 373   /// empty for external functions.
 374   ///
 375   const ArgumentListType &getArgumentList() const {
 376     CheckLazyArguments();
 377     return ArgumentList;
 378   }
 379   ArgumentListType &getArgumentList() {
 380     CheckLazyArguments();
 381     return ArgumentList;
 382   }
 383   static iplist<Argument> Function::*getSublistAccess(Argument*) {
 384     return &Function::ArgumentList;
 385   }
 386
 387   const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
 388         BasicBlockListType &getBasicBlockList()       { return BasicBlocks; }
 389   static iplist<BasicBlock> Function::*getSublistAccess(BasicBlock*) {
 390     return &Function::BasicBlocks;
 391   }
 392
 393   const BasicBlock       &getEntryBlock() const   { return front(); }
 394         BasicBlock       &getEntryBlock()         { return front(); }
 395
 396   //===--------------------------------------------------------------------===//
 397   // Symbol Table Accessing functions...
 398
 399   /// getSymbolTable() - Return the symbol table...
 400   ///
 401   inline       ValueSymbolTable &getValueSymbolTable()       { return *SymTab; }
 402   inline const ValueSymbolTable &getValueSymbolTable() const { return *SymTab; }
 403
 404
 405   //===--------------------------------------------------------------------===//
 406   // BasicBlock iterator forwarding functions
 407   //
 408   iterator                begin()       { return BasicBlocks.begin(); }
 409   const_iterator          begin() const { return BasicBlocks.begin(); }
 410   iterator                end  ()       { return BasicBlocks.end();   }
 411   const_iterator          end  () const { return BasicBlocks.end();   }
 412
 413   size_t                   size() const { return BasicBlocks.size();  }
 414   bool                    empty() const { return BasicBlocks.empty(); }
 415   const BasicBlock       &front() const { return BasicBlocks.front(); }
 416         BasicBlock       &front()       { return BasicBlocks.front(); }
 417   const BasicBlock        &back() const { return BasicBlocks.back();  }
 418         BasicBlock        &back()       { return BasicBlocks.back();  }
 419
 420 /// @name Function Argument Iteration
 421 /// @{
 422
 423   arg_iterator arg_begin() {
 424     CheckLazyArguments();
 425     return ArgumentList.begin();
 426   }
 427   const_arg_iterator arg_begin() const {
 428     CheckLazyArguments();
 429     return ArgumentList.begin();
 430   }
 431   arg_iterator arg_end() {
 432     CheckLazyArguments();
 433     return ArgumentList.end();
 434   }
 435   const_arg_iterator arg_end() const {
 436     CheckLazyArguments();
 437     return ArgumentList.end();
 438   }
 439
 440   iterator_range<arg_iterator> args() {
 441     return iterator_range<arg_iterator>(arg_begin(), arg_end());
 442   }
 443
 444   iterator_range<const_arg_iterator> args() const {
 445     return iterator_range<const_arg_iterator>(arg_begin(), arg_end());
 446   }
 447
 448 /// @}
 449
 450   size_t arg_size() const;
 451   bool arg_empty() const;
 452
 453   bool hasPrefixData() const {
 454     return getSubclassDataFromValue() & (1<<1);
 455   }
 456
 457   Constant *getPrefixData() const;
 458   void setPrefixData(Constant *PrefixData);
 459
 460   bool hasPrologueData() const {
 461     return getSubclassDataFromValue() & (1<<2);
 462   }
 463
 464   Constant *getPrologueData() const;
 465   void setPrologueData(Constant *PrologueData);
 466
 467   /// viewCFG - This function is meant for use from the debugger.  You can just
 468   /// say 'call F->viewCFG()' and a ghostview window should pop up from the
 469   /// program, displaying the CFG of the current function with the code for each
 470   /// basic block inside.  This depends on there being a 'dot' and 'gv' program
 471   /// in your path.
 472   ///
 473   void viewCFG() const;
 474
 475   /// viewCFGOnly - This function is meant for use from the debugger.  It works
 476   /// just like viewCFG, but it does not include the contents of basic blocks
 477   /// into the nodes, just the label.  If you are only interested in the CFG
 478   /// this can make the graph smaller.
 479   ///
 480   void viewCFGOnly() const;
 481
 482   /// Methods for support type inquiry through isa, cast, and dyn_cast:
 483   static inline bool classof(const Value *V) {
 484     return V->getValueID() == Value::FunctionVal;
 485   }
 486
 487   /// dropAllReferences() - This method causes all the subinstructions to "let
 488   /// go" of all references that they are maintaining.  This allows one to
 489   /// 'delete' a whole module at a time, even though there may be circular
 490   /// references... first all references are dropped, and all use counts go to
 491   /// zero.  Then everything is deleted for real.  Note that no operations are
 492   /// valid on an object that has "dropped all references", except operator
 493   /// delete.
 494   ///
 495   /// Since no other object in the module can have references into the body of a
 496   /// function, dropping all references deletes the entire body of the function,
 497   /// including any contained basic blocks.
 498   ///
 499   void dropAllReferences();
 500
 501   /// hasAddressTaken - returns true if there are any uses of this function
 502   /// other than direct calls or invokes to it, or blockaddress expressions.
 503   /// Optionally passes back an offending user for diagnostic purposes.
 504   ///
 505   bool hasAddressTaken(const User** = nullptr) const;
 506
 507   /// isDefTriviallyDead - Return true if it is trivially safe to remove
 508   /// this function definition from the module (because it isn't externally
 509   /// visible, does not have its address taken, and has no callers).  To make
 510   /// this more accurate, call removeDeadConstantUsers first.
 511   bool isDefTriviallyDead() const;
 512
 513   /// callsFunctionThatReturnsTwice - Return true if the function has a call to
 514   /// setjmp or other function that gcc recognizes as "returning twice".
 515   bool callsFunctionThatReturnsTwice() const;
 516
 517 private:
 518   // Shadow Value::setValueSubclassData with a private forwarding method so that
 519   // subclasses cannot accidentally use it.
 520   void setValueSubclassData(unsigned short D) {
 521     Value::setValueSubclassData(D);
 522   }
 523 };
 524
 525 inline ValueSymbolTable *
 526 ilist_traits<BasicBlock>::getSymTab(Function *F) {
 527   return F ? &F->getValueSymbolTable() : nullptr;
 528 }
 529
 530 inline ValueSymbolTable *
 531 ilist_traits<Argument>::getSymTab(Function *F) {
 532   return F ? &F->getValueSymbolTable() : nullptr;
 533 }
 534
 535 } // End llvm namespace
 536
 537 #endif