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/GlobalValue.h"
27 #include "llvm/Support/Compiler.h"
34 // Traits for intrusive list of basic blocks...
35 template<> struct ilist_traits<BasicBlock>
36 : public SymbolTableListTraits<BasicBlock, Function> {
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);
43 static void destroySentinel(BasicBlock*) {}
45 BasicBlock *provideInitialHead() const { return createSentinel(); }
46 BasicBlock *ensureHead(BasicBlock*) const { return createSentinel(); }
47 static void noteHead(BasicBlock*, BasicBlock*) {}
49 static ValueSymbolTable *getSymTab(Function *ItemParent);
51 mutable ilist_half_node<BasicBlock> Sentinel;
54 template<> struct ilist_traits<Argument>
55 : public SymbolTableListTraits<Argument, Function> {
57 Argument *createSentinel() const {
58 return static_cast<Argument*>(&Sentinel);
60 static void destroySentinel(Argument*) {}
62 Argument *provideInitialHead() const { return createSentinel(); }
63 Argument *ensureHead(Argument*) const { return createSentinel(); }
64 static void noteHead(Argument*, Argument*) {}
66 static ValueSymbolTable *getSymTab(Function *ItemParent);
68 mutable ilist_half_node<Argument> Sentinel;
71 class Function : public GlobalValue,
72 public ilist_node<Function> {
74 typedef iplist<Argument> ArgumentListType;
75 typedef iplist<BasicBlock> BasicBlockListType;
77 // BasicBlock iterators...
78 typedef BasicBlockListType::iterator iterator;
79 typedef BasicBlockListType::const_iterator const_iterator;
81 typedef ArgumentListType::iterator arg_iterator;
82 typedef ArgumentListType::const_iterator const_arg_iterator;
85 // Important things that make up a function!
86 BasicBlockListType BasicBlocks; ///< The basic blocks
87 mutable ArgumentListType ArgumentList; ///< The formal arguments
88 ValueSymbolTable *SymTab; ///< Symbol table of args/instructions
89 AttributeSet AttributeSets; ///< Parameter attributes
91 // HasLazyArguments is stored in Value::SubclassData.
92 /*bool HasLazyArguments;*/
94 // The Calling Convention is stored in Value::SubclassData.
95 /*CallingConv::ID CallingConvention;*/
97 friend class SymbolTableListTraits<Function, Module>;
99 void setParent(Module *parent);
101 /// hasLazyArguments/CheckLazyArguments - The argument list of a function is
102 /// built on demand, so that the list isn't allocated until the first client
103 /// needs it. The hasLazyArguments predicate returns true if the arg list
104 /// hasn't been set up yet.
105 bool hasLazyArguments() const {
106 return getSubclassDataFromValue() & 1;
108 void CheckLazyArguments() const {
109 if (hasLazyArguments())
110 BuildLazyArguments();
112 void BuildLazyArguments() const;
114 Function(const Function&) LLVM_DELETED_FUNCTION;
115 void operator=(const Function&) LLVM_DELETED_FUNCTION;
117 /// Do the actual lookup of an intrinsic ID when the query could not be
118 /// answered from the cache.
119 unsigned lookupIntrinsicID() const LLVM_READONLY;
121 /// Function ctor - If the (optional) Module argument is specified, the
122 /// function is automatically inserted into the end of the function list for
125 Function(FunctionType *Ty, LinkageTypes Linkage,
126 const Twine &N = "", Module *M = nullptr);
129 static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
130 const Twine &N = "", Module *M = nullptr) {
131 return new(0) Function(Ty, Linkage, N, M);
136 Type *getReturnType() const; // Return the type of the ret val
137 FunctionType *getFunctionType() const; // Return the FunctionType for me
139 /// getContext - Return a pointer to the LLVMContext associated with this
140 /// function, or NULL if this function is not bound to a context yet.
141 LLVMContext &getContext() const;
143 /// isVarArg - Return true if this function takes a variable number of
145 bool isVarArg() const;
147 /// getIntrinsicID - This method returns the ID number of the specified
148 /// function, or Intrinsic::not_intrinsic if the function is not an
149 /// intrinsic, or if the pointer is null. This value is always defined to be
150 /// zero to allow easy checking for whether a function is intrinsic or not.
151 /// The particular intrinsic functions which correspond to this value are
152 /// defined in llvm/Intrinsics.h. Results are cached in the LLVM context,
153 /// subsequent requests for the same ID return results much faster from the
156 unsigned getIntrinsicID() const LLVM_READONLY;
157 bool isIntrinsic() const { return getName().startswith("llvm."); }
159 /// getCallingConv()/setCallingConv(CC) - These method get and set the
160 /// calling convention of this function. The enum values for the known
161 /// calling conventions are defined in CallingConv.h.
162 CallingConv::ID getCallingConv() const {
163 return static_cast<CallingConv::ID>(getSubclassDataFromValue() >> 2);
165 void setCallingConv(CallingConv::ID CC) {
166 setValueSubclassData((getSubclassDataFromValue() & 3) |
167 (static_cast<unsigned>(CC) << 2));
170 /// @brief Return the attribute list for this Function.
171 AttributeSet getAttributes() const { return AttributeSets; }
173 /// @brief Set the attribute list for this Function.
174 void setAttributes(AttributeSet attrs) { AttributeSets = attrs; }
176 /// @brief Add function attributes to this function.
177 void addFnAttr(Attribute::AttrKind N) {
178 setAttributes(AttributeSets.addAttribute(getContext(),
179 AttributeSet::FunctionIndex, N));
182 /// @brief Remove function attributes from this function.
183 void removeFnAttr(Attribute::AttrKind N) {
184 setAttributes(AttributeSets.removeAttribute(
185 getContext(), AttributeSet::FunctionIndex, N));
188 /// @brief Add function attributes to this function.
189 void addFnAttr(StringRef Kind) {
191 AttributeSets.addAttribute(getContext(),
192 AttributeSet::FunctionIndex, Kind));
194 void addFnAttr(StringRef Kind, StringRef Value) {
196 AttributeSets.addAttribute(getContext(),
197 AttributeSet::FunctionIndex, Kind, Value));
200 /// @brief Return true if the function has the attribute.
201 bool hasFnAttribute(Attribute::AttrKind Kind) const {
202 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
204 bool hasFnAttribute(StringRef Kind) const {
205 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
208 /// @brief Return the attribute for the given attribute kind.
209 Attribute getFnAttribute(Attribute::AttrKind Kind) const {
210 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
212 Attribute getFnAttribute(StringRef Kind) const {
213 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
216 /// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
217 /// to use during code generation.
219 const char *getGC() const;
220 void setGC(const char *Str);
223 /// @brief adds the attribute to the list of attributes.
224 void addAttribute(unsigned i, Attribute::AttrKind attr);
226 /// @brief adds the attributes to the list of attributes.
227 void addAttributes(unsigned i, AttributeSet attrs);
229 /// @brief removes the attributes from the list of attributes.
230 void removeAttributes(unsigned i, AttributeSet attr);
232 /// @brief Extract the alignment for a call or parameter (0=unknown).
233 unsigned getParamAlignment(unsigned i) const {
234 return AttributeSets.getParamAlignment(i);
237 /// @brief Determine if the function does not access memory.
238 bool doesNotAccessMemory() const {
239 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
240 Attribute::ReadNone);
242 void setDoesNotAccessMemory() {
243 addFnAttr(Attribute::ReadNone);
246 /// @brief Determine if the function does not access or only reads memory.
247 bool onlyReadsMemory() const {
248 return doesNotAccessMemory() ||
249 AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
250 Attribute::ReadOnly);
252 void setOnlyReadsMemory() {
253 addFnAttr(Attribute::ReadOnly);
256 /// @brief Determine if the function cannot return.
257 bool doesNotReturn() const {
258 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
259 Attribute::NoReturn);
261 void setDoesNotReturn() {
262 addFnAttr(Attribute::NoReturn);
265 /// @brief Determine if the function cannot unwind.
266 bool doesNotThrow() const {
267 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
268 Attribute::NoUnwind);
270 void setDoesNotThrow() {
271 addFnAttr(Attribute::NoUnwind);
274 /// @brief Determine if the call cannot be duplicated.
275 bool cannotDuplicate() const {
276 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
277 Attribute::NoDuplicate);
279 void setCannotDuplicate() {
280 addFnAttr(Attribute::NoDuplicate);
283 /// @brief True if the ABI mandates (or the user requested) that this
284 /// function be in a unwind table.
285 bool hasUWTable() const {
286 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
289 void setHasUWTable() {
290 addFnAttr(Attribute::UWTable);
293 /// @brief True if this function needs an unwind table.
294 bool needsUnwindTableEntry() const {
295 return hasUWTable() || !doesNotThrow();
298 /// @brief Determine if the function returns a structure through first
299 /// pointer argument.
300 bool hasStructRetAttr() const {
301 return AttributeSets.hasAttribute(1, Attribute::StructRet);
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);
309 void setDoesNotAlias(unsigned n) {
310 addAttribute(n, Attribute::NoAlias);
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);
318 void setDoesNotCapture(unsigned n) {
319 addAttribute(n, Attribute::NoCapture);
322 bool doesNotAccessMemory(unsigned n) const {
323 return AttributeSets.hasAttribute(n, Attribute::ReadNone);
325 void setDoesNotAccessMemory(unsigned n) {
326 addAttribute(n, Attribute::ReadNone);
329 bool onlyReadsMemory(unsigned n) const {
330 return doesNotAccessMemory(n) ||
331 AttributeSets.hasAttribute(n, Attribute::ReadOnly);
333 void setOnlyReadsMemory(unsigned n) {
334 addAttribute(n, Attribute::ReadOnly);
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;
341 /// deleteBody - This method deletes the body of the function, and converts
342 /// the linkage to external.
346 setLinkage(ExternalLinkage);
349 /// removeFromParent - This method unlinks 'this' from the containing module,
350 /// but does not delete it.
352 void removeFromParent() override;
354 /// eraseFromParent - This method unlinks 'this' from the containing module
357 void eraseFromParent() override;
360 /// Get the underlying elements of the Function... the basic block list is
361 /// empty for external functions.
363 const ArgumentListType &getArgumentList() const {
364 CheckLazyArguments();
367 ArgumentListType &getArgumentList() {
368 CheckLazyArguments();
371 static iplist<Argument> Function::*getSublistAccess(Argument*) {
372 return &Function::ArgumentList;
375 const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
376 BasicBlockListType &getBasicBlockList() { return BasicBlocks; }
377 static iplist<BasicBlock> Function::*getSublistAccess(BasicBlock*) {
378 return &Function::BasicBlocks;
381 const BasicBlock &getEntryBlock() const { return front(); }
382 BasicBlock &getEntryBlock() { return front(); }
384 //===--------------------------------------------------------------------===//
385 // Symbol Table Accessing functions...
387 /// getSymbolTable() - Return the symbol table...
389 inline ValueSymbolTable &getValueSymbolTable() { return *SymTab; }
390 inline const ValueSymbolTable &getValueSymbolTable() const { return *SymTab; }
393 //===--------------------------------------------------------------------===//
394 // BasicBlock iterator forwarding functions
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(); }
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(); }
408 /// @name Function Argument Iteration
411 arg_iterator arg_begin() {
412 CheckLazyArguments();
413 return ArgumentList.begin();
415 const_arg_iterator arg_begin() const {
416 CheckLazyArguments();
417 return ArgumentList.begin();
419 arg_iterator arg_end() {
420 CheckLazyArguments();
421 return ArgumentList.end();
423 const_arg_iterator arg_end() const {
424 CheckLazyArguments();
425 return ArgumentList.end();
428 iterator_range<arg_iterator> args() {
429 return iterator_range<arg_iterator>(arg_begin(), arg_end());
432 iterator_range<const_arg_iterator> args() const {
433 return iterator_range<const_arg_iterator>(arg_begin(), arg_end());
438 size_t arg_size() const;
439 bool arg_empty() const;
441 bool hasPrefixData() const {
442 return getSubclassDataFromValue() & 2;
445 Constant *getPrefixData() const;
446 void setPrefixData(Constant *PrefixData);
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
454 void viewCFG() const;
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.
461 void viewCFGOnly() const;
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;
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
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.
480 void dropAllReferences();
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.
486 bool hasAddressTaken(const User** = nullptr) const;
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;
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;
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);
506 inline ValueSymbolTable *
507 ilist_traits<BasicBlock>::getSymTab(Function *F) {
508 return F ? &F->getValueSymbolTable() : nullptr;
511 inline ValueSymbolTable *
512 ilist_traits<Argument>::getSymTab(Function *F) {
513 return F ? &F->getValueSymbolTable() : nullptr;
516 } // End llvm namespace