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 // 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 GlobalObject, public ilist_node<Function> {
73 typedef iplist<Argument> ArgumentListType;
74 typedef iplist<BasicBlock> BasicBlockListType;
76 // BasicBlock iterators...
77 typedef BasicBlockListType::iterator iterator;
78 typedef BasicBlockListType::const_iterator const_iterator;
80 typedef ArgumentListType::iterator arg_iterator;
81 typedef ArgumentListType::const_iterator const_arg_iterator;
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
90 // HasLazyArguments is stored in Value::SubclassData.
91 /*bool HasLazyArguments;*/
93 // The Calling Convention is stored in Value::SubclassData.
94 /*CallingConv::ID CallingConvention;*/
96 friend class SymbolTableListTraits<Function, Module>;
98 void setParent(Module *parent);
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;
107 void CheckLazyArguments() const {
108 if (hasLazyArguments())
109 BuildLazyArguments();
111 void BuildLazyArguments() const;
113 Function(const Function&) LLVM_DELETED_FUNCTION;
114 void operator=(const Function&) LLVM_DELETED_FUNCTION;
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;
120 /// Function ctor - If the (optional) Module argument is specified, the
121 /// function is automatically inserted into the end of the function list for
124 Function(FunctionType *Ty, LinkageTypes Linkage,
125 const Twine &N = "", Module *M = nullptr);
128 static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
129 const Twine &N = "", Module *M = nullptr) {
130 return new(0) Function(Ty, Linkage, N, M);
135 Type *getReturnType() const; // Return the type of the ret val
136 FunctionType *getFunctionType() const; // Return the FunctionType for me
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;
142 /// isVarArg - Return true if this function takes a variable number of
144 bool isVarArg() const;
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
155 unsigned getIntrinsicID() const LLVM_READONLY;
156 bool isIntrinsic() const { return getName().startswith("llvm."); }
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);
164 void setCallingConv(CallingConv::ID CC) {
165 setValueSubclassData((getSubclassDataFromValue() & 3) |
166 (static_cast<unsigned>(CC) << 2));
169 /// @brief Return the attribute list for this Function.
170 AttributeSet getAttributes() const { return AttributeSets; }
172 /// @brief Set the attribute list for this Function.
173 void setAttributes(AttributeSet attrs) { AttributeSets = attrs; }
175 /// @brief Add function attributes to this function.
176 void addFnAttr(Attribute::AttrKind N) {
177 setAttributes(AttributeSets.addAttribute(getContext(),
178 AttributeSet::FunctionIndex, N));
181 /// @brief Remove function attributes from this function.
182 void removeFnAttr(Attribute::AttrKind N) {
183 setAttributes(AttributeSets.removeAttribute(
184 getContext(), AttributeSet::FunctionIndex, N));
187 /// @brief Add function attributes to this function.
188 void addFnAttr(StringRef Kind) {
190 AttributeSets.addAttribute(getContext(),
191 AttributeSet::FunctionIndex, Kind));
193 void addFnAttr(StringRef Kind, StringRef Value) {
195 AttributeSets.addAttribute(getContext(),
196 AttributeSet::FunctionIndex, Kind, Value));
199 /// @brief Return true if the function has the attribute.
200 bool hasFnAttribute(Attribute::AttrKind Kind) const {
201 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
203 bool hasFnAttribute(StringRef Kind) const {
204 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
207 /// @brief Return the attribute for the given attribute kind.
208 Attribute getFnAttribute(Attribute::AttrKind Kind) const {
209 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
211 Attribute getFnAttribute(StringRef Kind) const {
212 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
215 /// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
216 /// to use during code generation.
218 const char *getGC() const;
219 void setGC(const char *Str);
222 /// @brief adds the attribute to the list of attributes.
223 void addAttribute(unsigned i, Attribute::AttrKind attr);
225 /// @brief adds the attributes to the list of attributes.
226 void addAttributes(unsigned i, AttributeSet attrs);
228 /// @brief removes the attributes from the list of attributes.
229 void removeAttributes(unsigned i, AttributeSet attr);
231 /// @brief Extract the alignment for a call or parameter (0=unknown).
232 unsigned getParamAlignment(unsigned i) const {
233 return AttributeSets.getParamAlignment(i);
236 /// @brief Determine if the function does not access memory.
237 bool doesNotAccessMemory() const {
238 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
239 Attribute::ReadNone);
241 void setDoesNotAccessMemory() {
242 addFnAttr(Attribute::ReadNone);
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);
251 void setOnlyReadsMemory() {
252 addFnAttr(Attribute::ReadOnly);
255 /// @brief Determine if the function cannot return.
256 bool doesNotReturn() const {
257 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
258 Attribute::NoReturn);
260 void setDoesNotReturn() {
261 addFnAttr(Attribute::NoReturn);
264 /// @brief Determine if the function cannot unwind.
265 bool doesNotThrow() const {
266 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
267 Attribute::NoUnwind);
269 void setDoesNotThrow() {
270 addFnAttr(Attribute::NoUnwind);
273 /// @brief Determine if the call cannot be duplicated.
274 bool cannotDuplicate() const {
275 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
276 Attribute::NoDuplicate);
278 void setCannotDuplicate() {
279 addFnAttr(Attribute::NoDuplicate);
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,
288 void setHasUWTable() {
289 addFnAttr(Attribute::UWTable);
292 /// @brief True if this function needs an unwind table.
293 bool needsUnwindTableEntry() const {
294 return hasUWTable() || !doesNotThrow();
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);
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