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 538