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