1 //===-- llvm/Function.h - Class to represent a single function --*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the declaration of the Function class, which represents a
11 // single function/procedure in LLVM.
13 // A function basically consists of a list of basic blocks, a list of arguments,
14 // and a symbol table.
16 //===----------------------------------------------------------------------===//
18 #ifndef LLVM_IR_FUNCTION_H
19 #define LLVM_IR_FUNCTION_H
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"
34 template<> struct ilist_traits<Argument>
35 : public SymbolTableListTraits<Argument, Function> {
37 Argument *createSentinel() const {
38 return static_cast<Argument*>(&Sentinel);
40 static void destroySentinel(Argument*) {}
42 Argument *provideInitialHead() const { return createSentinel(); }
43 Argument *ensureHead(Argument*) const { return createSentinel(); }
44 static void noteHead(Argument*, Argument*) {}
46 static ValueSymbolTable *getSymTab(Function *ItemParent);
48 mutable ilist_half_node<Argument> Sentinel;
51 class Function : public GlobalObject, public ilist_node<Function> {
53 typedef iplist<Argument> ArgumentListType;
54 typedef iplist<BasicBlock> BasicBlockListType;
56 // BasicBlock iterators...
57 typedef BasicBlockListType::iterator iterator;
58 typedef BasicBlockListType::const_iterator const_iterator;
60 typedef ArgumentListType::iterator arg_iterator;
61 typedef ArgumentListType::const_iterator const_arg_iterator;
64 // Important things that make up a function!
65 BasicBlockListType BasicBlocks; ///< The basic blocks
66 mutable ArgumentListType ArgumentList; ///< The formal arguments
67 ValueSymbolTable *SymTab; ///< Symbol table of args/instructions
68 AttributeSet AttributeSets; ///< Parameter attributes
74 * bit 0 : HasLazyArguments
75 * bit 1 : HasPrefixData
76 * bit 2 : HasPrologueData
77 * bit 3-6: CallingConvention
80 /// Bits from GlobalObject::GlobalObjectSubclassData.
82 /// Whether this function is materializable.
83 IsMaterializableBit = 1 << 0
85 void setGlobalObjectBit(unsigned Mask, bool Value) {
86 setGlobalObjectSubClassData((~Mask & getGlobalObjectSubClassData()) |
90 friend class SymbolTableListTraits<Function, Module>;
92 void setParent(Module *parent);
94 /// hasLazyArguments/CheckLazyArguments - The argument list of a function is
95 /// built on demand, so that the list isn't allocated until the first client
96 /// needs it. The hasLazyArguments predicate returns true if the arg list
97 /// hasn't been set up yet.
98 bool hasLazyArguments() const {
99 return getSubclassDataFromValue() & (1<<0);
101 void CheckLazyArguments() const {
102 if (hasLazyArguments())
103 BuildLazyArguments();
105 void BuildLazyArguments() const;
107 Function(const Function&) = delete;
108 void operator=(const Function&) = delete;
110 /// Do the actual lookup of an intrinsic ID when the query could not be
111 /// answered from the cache.
112 unsigned lookupIntrinsicID() const LLVM_READONLY;
114 /// Function ctor - If the (optional) Module argument is specified, the
115 /// function is automatically inserted into the end of the function list for
118 Function(FunctionType *Ty, LinkageTypes Linkage,
119 const Twine &N = "", Module *M = nullptr);
122 static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
123 const Twine &N = "", Module *M = nullptr) {
124 return new(0) Function(Ty, Linkage, N, M);
127 ~Function() override;
129 Type *getReturnType() const; // Return the type of the ret val
130 FunctionType *getFunctionType() const; // Return the FunctionType for me
132 /// getContext - Return a pointer to the LLVMContext associated with this
133 /// function, or NULL if this function is not bound to a context yet.
134 LLVMContext &getContext() const;
136 /// isVarArg - Return true if this function takes a variable number of
138 bool isVarArg() const;
140 bool isMaterializable() const;
141 void setIsMaterializable(bool V);
143 /// getIntrinsicID - This method returns the ID number of the specified
144 /// function, or Intrinsic::not_intrinsic if the function is not an
145 /// intrinsic, or if the pointer is null. This value is always defined to be
146 /// zero to allow easy checking for whether a function is intrinsic or not.
147 /// The particular intrinsic functions which correspond to this value are
148 /// defined in llvm/Intrinsics.h. Results are cached in the LLVM context,
149 /// subsequent requests for the same ID return results much faster from the
152 unsigned getIntrinsicID() const LLVM_READONLY;
153 bool isIntrinsic() const { return getName().startswith("llvm."); }
155 /// getCallingConv()/setCallingConv(CC) - These method get and set the
156 /// calling convention of this function. The enum values for the known
157 /// calling conventions are defined in CallingConv.h.
158 CallingConv::ID getCallingConv() const {
159 return static_cast<CallingConv::ID>(getSubclassDataFromValue() >> 3);
161 void setCallingConv(CallingConv::ID CC) {
162 setValueSubclassData((getSubclassDataFromValue() & 7) |
163 (static_cast<unsigned>(CC) << 3));
166 /// @brief Return the attribute list for this Function.
167 AttributeSet getAttributes() const { return AttributeSets; }
169 /// @brief Set the attribute list for this Function.
170 void setAttributes(AttributeSet attrs) { AttributeSets = attrs; }
172 /// @brief Add function attributes to this function.
173 void addFnAttr(Attribute::AttrKind N) {
174 setAttributes(AttributeSets.addAttribute(getContext(),
175 AttributeSet::FunctionIndex, N));
178 /// @brief Remove function attributes from this function.
179 void removeFnAttr(Attribute::AttrKind N) {
180 setAttributes(AttributeSets.removeAttribute(
181 getContext(), AttributeSet::FunctionIndex, N));
184 /// @brief Add function attributes to this function.
185 void addFnAttr(StringRef Kind) {
187 AttributeSets.addAttribute(getContext(),
188 AttributeSet::FunctionIndex, Kind));
190 void addFnAttr(StringRef Kind, StringRef Value) {
192 AttributeSets.addAttribute(getContext(),
193 AttributeSet::FunctionIndex, Kind, Value));
196 /// @brief Return true if the function has the attribute.
197 bool hasFnAttribute(Attribute::AttrKind Kind) const {
198 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
200 bool hasFnAttribute(StringRef Kind) const {
201 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
204 /// @brief Return the attribute for the given attribute kind.
205 Attribute getFnAttribute(Attribute::AttrKind Kind) const {
206 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
208 Attribute getFnAttribute(StringRef Kind) const {
209 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
212 /// \brief Return the stack alignment for the function.
213 unsigned getFnStackAlignment() const {
214 return AttributeSets.getStackAlignment(AttributeSet::FunctionIndex);
217 /// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
218 /// to use during code generation.
220 const char *getGC() const;
221 void setGC(const char *Str);
224 /// @brief adds the attribute to the list of attributes.
225 void addAttribute(unsigned i, Attribute::AttrKind attr);
227 /// @brief adds the attributes to the list of attributes.
228 void addAttributes(unsigned i, AttributeSet attrs);
230 /// @brief removes the attributes from the list of attributes.
231 void removeAttributes(unsigned i, AttributeSet attr);
233 /// @brief adds the dereferenceable attribute to the list of attributes.
234 void addDereferenceableAttr(unsigned i, uint64_t Bytes);
236 /// @brief adds the dereferenceable_or_null attribute to the list of
238 void addDereferenceableOrNullAttr(unsigned i, uint64_t Bytes);
240 /// @brief Extract the alignment for a call or parameter (0=unknown).
241 unsigned getParamAlignment(unsigned i) const {
242 return AttributeSets.getParamAlignment(i);
245 /// @brief Extract the number of dereferenceable bytes for a call or
246 /// parameter (0=unknown).
247 uint64_t getDereferenceableBytes(unsigned i) const {
248 return AttributeSets.getDereferenceableBytes(i);
251 /// @brief Determine if the function does not access memory.
252 bool doesNotAccessMemory() const {
253 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
254 Attribute::ReadNone);
256 void setDoesNotAccessMemory() {
257 addFnAttr(Attribute::ReadNone);
260 /// @brief Determine if the function does not access or only reads memory.
261 bool onlyReadsMemory() const {
262 return doesNotAccessMemory() ||
263 AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
264 Attribute::ReadOnly);
266 void setOnlyReadsMemory() {
267 addFnAttr(Attribute::ReadOnly);
270 /// @brief Determine if the function cannot return.
271 bool doesNotReturn() const {
272 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
273 Attribute::NoReturn);
275 void setDoesNotReturn() {
276 addFnAttr(Attribute::NoReturn);
279 /// @brief Determine if the function cannot unwind.
280 bool doesNotThrow() const {
281 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
282 Attribute::NoUnwind);
284 void setDoesNotThrow() {
285 addFnAttr(Attribute::NoUnwind);
288 /// @brief Determine if the call cannot be duplicated.
289 bool cannotDuplicate() const {
290 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
291 Attribute::NoDuplicate);
293 void setCannotDuplicate() {
294 addFnAttr(Attribute::NoDuplicate);
297 /// @brief True if the ABI mandates (or the user requested) that this
298 /// function be in a unwind table.
299 bool hasUWTable() const {
300 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
303 void setHasUWTable() {
304 addFnAttr(Attribute::UWTable);
307 /// @brief True if this function needs an unwind table.
308 bool needsUnwindTableEntry() const {
309 return hasUWTable() || !doesNotThrow();
312 /// @brief Determine if the function returns a structure through first
313 /// pointer argument.
314 bool hasStructRetAttr() const {
315 return AttributeSets.hasAttribute(1, Attribute::StructRet) ||
316 AttributeSets.hasAttribute(2, Attribute::StructRet);
319 /// @brief Determine if the parameter does not alias other parameters.
320 /// @param n The parameter to check. 1 is the first parameter, 0 is the return
321 bool doesNotAlias(unsigned n) const {
322 return AttributeSets.hasAttribute(n, Attribute::NoAlias);
324 void setDoesNotAlias(unsigned n) {
325 addAttribute(n, Attribute::NoAlias);
328 /// @brief Determine if the parameter can be captured.
329 /// @param n The parameter to check. 1 is the first parameter, 0 is the return
330 bool doesNotCapture(unsigned n) const {
331 return AttributeSets.hasAttribute(n, Attribute::NoCapture);
333 void setDoesNotCapture(unsigned n) {
334 addAttribute(n, Attribute::NoCapture);
337 bool doesNotAccessMemory(unsigned n) const {
338 return AttributeSets.hasAttribute(n, Attribute::ReadNone);
340 void setDoesNotAccessMemory(unsigned n) {
341 addAttribute(n, Attribute::ReadNone);
344 bool onlyReadsMemory(unsigned n) const {
345 return doesNotAccessMemory(n) ||
346 AttributeSets.hasAttribute(n, Attribute::ReadOnly);
348 void setOnlyReadsMemory(unsigned n) {
349 addAttribute(n, Attribute::ReadOnly);
352 /// copyAttributesFrom - copy all additional attributes (those not needed to
353 /// create a Function) from the Function Src to this one.
354 void copyAttributesFrom(const GlobalValue *Src) override;
356 /// deleteBody - This method deletes the body of the function, and converts
357 /// the linkage to external.
361 setLinkage(ExternalLinkage);
364 /// removeFromParent - This method unlinks 'this' from the containing module,
365 /// but does not delete it.
367 void removeFromParent() override;
369 /// eraseFromParent - This method unlinks 'this' from the containing module
372 void eraseFromParent() override;
375 /// Get the underlying elements of the Function... the basic block list is
376 /// empty for external functions.
378 const ArgumentListType &getArgumentList() const {
379 CheckLazyArguments();
382 ArgumentListType &getArgumentList() {
383 CheckLazyArguments();
386 static iplist<Argument> Function::*getSublistAccess(Argument*) {
387 return &Function::ArgumentList;
390 const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
391 BasicBlockListType &getBasicBlockList() { return BasicBlocks; }
392 static iplist<BasicBlock> Function::*getSublistAccess(BasicBlock*) {
393 return &Function::BasicBlocks;
396 const BasicBlock &getEntryBlock() const { return front(); }
397 BasicBlock &getEntryBlock() { return front(); }
399 //===--------------------------------------------------------------------===//
400 // Symbol Table Accessing functions...
402 /// getSymbolTable() - Return the symbol table...
404 inline ValueSymbolTable &getValueSymbolTable() { return *SymTab; }
405 inline const ValueSymbolTable &getValueSymbolTable() const { return *SymTab; }
408 //===--------------------------------------------------------------------===//
409 // BasicBlock iterator forwarding functions
411 iterator begin() { return BasicBlocks.begin(); }
412 const_iterator begin() const { return BasicBlocks.begin(); }
413 iterator end () { return BasicBlocks.end(); }
414 const_iterator end () const { return BasicBlocks.end(); }
416 size_t size() const { return BasicBlocks.size(); }
417 bool empty() const { return BasicBlocks.empty(); }
418 const BasicBlock &front() const { return BasicBlocks.front(); }
419 BasicBlock &front() { return BasicBlocks.front(); }
420 const BasicBlock &back() const { return BasicBlocks.back(); }
421 BasicBlock &back() { return BasicBlocks.back(); }
423 /// @name Function Argument Iteration
426 arg_iterator arg_begin() {
427 CheckLazyArguments();
428 return ArgumentList.begin();
430 const_arg_iterator arg_begin() const {
431 CheckLazyArguments();
432 return ArgumentList.begin();
434 arg_iterator arg_end() {
435 CheckLazyArguments();
436 return ArgumentList.end();
438 const_arg_iterator arg_end() const {
439 CheckLazyArguments();
440 return ArgumentList.end();
443 iterator_range<arg_iterator> args() {
444 return iterator_range<arg_iterator>(arg_begin(), arg_end());
447 iterator_range<const_arg_iterator> args() const {
448 return iterator_range<const_arg_iterator>(arg_begin(), arg_end());
453 size_t arg_size() const;
454 bool arg_empty() const;
456 bool hasPrefixData() const {
457 return getSubclassDataFromValue() & (1<<1);
460 Constant *getPrefixData() const;
461 void setPrefixData(Constant *PrefixData);
463 bool hasPrologueData() const {
464 return getSubclassDataFromValue() & (1<<2);
467 Constant *getPrologueData() const;
468 void setPrologueData(Constant *PrologueData);
470 /// Print the function to an output stream with an optional
471 /// AssemblyAnnotationWriter.
472 void print(raw_ostream &OS, AssemblyAnnotationWriter *AAW = nullptr) const;
474 /// viewCFG - This function is meant for use from the debugger. You can just
475 /// say 'call F->viewCFG()' and a ghostview window should pop up from the
476 /// program, displaying the CFG of the current function with the code for each
477 /// basic block inside. This depends on there being a 'dot' and 'gv' program
480 void viewCFG() const;
482 /// viewCFGOnly - This function is meant for use from the debugger. It works
483 /// just like viewCFG, but it does not include the contents of basic blocks
484 /// into the nodes, just the label. If you are only interested in the CFG
485 /// this can make the graph smaller.
487 void viewCFGOnly() const;
489 /// Methods for support type inquiry through isa, cast, and dyn_cast:
490 static inline bool classof(const Value *V) {
491 return V->getValueID() == Value::FunctionVal;
494 /// dropAllReferences() - This method causes all the subinstructions to "let
495 /// go" of all references that they are maintaining. This allows one to
496 /// 'delete' a whole module at a time, even though there may be circular
497 /// references... first all references are dropped, and all use counts go to
498 /// zero. Then everything is deleted for real. Note that no operations are
499 /// valid on an object that has "dropped all references", except operator
502 /// Since no other object in the module can have references into the body of a
503 /// function, dropping all references deletes the entire body of the function,
504 /// including any contained basic blocks.
506 void dropAllReferences();
508 /// hasAddressTaken - returns true if there are any uses of this function
509 /// other than direct calls or invokes to it, or blockaddress expressions.
510 /// Optionally passes back an offending user for diagnostic purposes.
512 bool hasAddressTaken(const User** = nullptr) const;
514 /// isDefTriviallyDead - Return true if it is trivially safe to remove
515 /// this function definition from the module (because it isn't externally
516 /// visible, does not have its address taken, and has no callers). To make
517 /// this more accurate, call removeDeadConstantUsers first.
518 bool isDefTriviallyDead() const;
520 /// callsFunctionThatReturnsTwice - Return true if the function has a call to
521 /// setjmp or other function that gcc recognizes as "returning twice".
522 bool callsFunctionThatReturnsTwice() const;
525 // Shadow Value::setValueSubclassData with a private forwarding method so that
526 // subclasses cannot accidentally use it.
527 void setValueSubclassData(unsigned short D) {
528 Value::setValueSubclassData(D);
532 inline ValueSymbolTable *
533 ilist_traits<BasicBlock>::getSymTab(Function *F) {
534 return F ? &F->getValueSymbolTable() : nullptr;
537 inline ValueSymbolTable *
538 ilist_traits<Argument>::getSymTab(Function *F) {
539 return F ? &F->getValueSymbolTable() : nullptr;
542 } // End llvm namespace