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 friend class SymbolTableListTraits<Function, Module>;
82 void setParent(Module *parent);
84 /// hasLazyArguments/CheckLazyArguments - The argument list of a function is
85 /// built on demand, so that the list isn't allocated until the first client
86 /// needs it. The hasLazyArguments predicate returns true if the arg list
87 /// hasn't been set up yet.
88 bool hasLazyArguments() const {
89 return getSubclassDataFromValue() & (1<<0);
91 void CheckLazyArguments() const {
92 if (hasLazyArguments())
95 void BuildLazyArguments() const;
97 Function(const Function&) = delete;
98 void operator=(const Function&) = delete;
100 /// Do the actual lookup of an intrinsic ID when the query could not be
101 /// answered from the cache.
102 unsigned lookupIntrinsicID() const LLVM_READONLY;
104 /// Function ctor - If the (optional) Module argument is specified, the
105 /// function is automatically inserted into the end of the function list for
108 Function(FunctionType *Ty, LinkageTypes Linkage,
109 const Twine &N = "", Module *M = nullptr);
112 static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
113 const Twine &N = "", Module *M = nullptr) {
114 return new(0) Function(Ty, Linkage, N, M);
117 ~Function() override;
119 Type *getReturnType() const; // Return the type of the ret val
120 FunctionType *getFunctionType() const; // Return the FunctionType for me
122 /// getContext - Return a pointer to the LLVMContext associated with this
123 /// function, or NULL if this function is not bound to a context yet.
124 LLVMContext &getContext() const;
126 /// isVarArg - Return true if this function takes a variable number of
128 bool isVarArg() const;
130 bool isMaterializable() const;
131 void setIsMaterializable(bool V);
133 /// getIntrinsicID - This method returns the ID number of the specified
134 /// function, or Intrinsic::not_intrinsic if the function is not an
135 /// intrinsic, or if the pointer is null. This value is always defined to be
136 /// zero to allow easy checking for whether a function is intrinsic or not.
137 /// The particular intrinsic functions which correspond to this value are
138 /// defined in llvm/Intrinsics.h. Results are cached in the LLVM context,
139 /// subsequent requests for the same ID return results much faster from the
142 unsigned getIntrinsicID() const LLVM_READONLY;
143 bool isIntrinsic() const { return getName().startswith("llvm."); }
145 /// getCallingConv()/setCallingConv(CC) - These method get and set the
146 /// calling convention of this function. The enum values for the known
147 /// calling conventions are defined in CallingConv.h.
148 CallingConv::ID getCallingConv() const {
149 return static_cast<CallingConv::ID>(getSubclassDataFromValue() >> 3);
151 void setCallingConv(CallingConv::ID CC) {
152 setValueSubclassData((getSubclassDataFromValue() & 7) |
153 (static_cast<unsigned>(CC) << 3));
156 /// @brief Return the attribute list for this Function.
157 AttributeSet getAttributes() const { return AttributeSets; }
159 /// @brief Set the attribute list for this Function.
160 void setAttributes(AttributeSet attrs) { AttributeSets = attrs; }
162 /// @brief Add function attributes to this function.
163 void addFnAttr(Attribute::AttrKind N) {
164 setAttributes(AttributeSets.addAttribute(getContext(),
165 AttributeSet::FunctionIndex, N));
168 /// @brief Remove function attributes from this function.
169 void removeFnAttr(Attribute::AttrKind N) {
170 setAttributes(AttributeSets.removeAttribute(
171 getContext(), AttributeSet::FunctionIndex, N));
174 /// @brief Add function attributes to this function.
175 void addFnAttr(StringRef Kind) {
177 AttributeSets.addAttribute(getContext(),
178 AttributeSet::FunctionIndex, Kind));
180 void addFnAttr(StringRef Kind, StringRef Value) {
182 AttributeSets.addAttribute(getContext(),
183 AttributeSet::FunctionIndex, Kind, Value));
186 /// @brief Return true if the function has the attribute.
187 bool hasFnAttribute(Attribute::AttrKind Kind) const {
188 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
190 bool hasFnAttribute(StringRef Kind) const {
191 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
194 /// @brief Return the attribute for the given attribute kind.
195 Attribute getFnAttribute(Attribute::AttrKind Kind) const {
196 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
198 Attribute getFnAttribute(StringRef Kind) const {
199 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
202 /// \brief Return the stack alignment for the function.
203 unsigned getFnStackAlignment() const {
204 return AttributeSets.getStackAlignment(AttributeSet::FunctionIndex);
207 /// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
208 /// to use during code generation.
210 const char *getGC() const;
211 void setGC(const char *Str);
214 /// @brief adds the attribute to the list of attributes.
215 void addAttribute(unsigned i, Attribute::AttrKind attr);
217 /// @brief adds the attributes to the list of attributes.
218 void addAttributes(unsigned i, AttributeSet attrs);
220 /// @brief removes the attributes from the list of attributes.
221 void removeAttributes(unsigned i, AttributeSet attr);
223 /// @brief adds the dereferenceable attribute to the list of attributes.
224 void addDereferenceableAttr(unsigned i, uint64_t Bytes);
226 /// @brief Extract the alignment for a call or parameter (0=unknown).
227 unsigned getParamAlignment(unsigned i) const {
228 return AttributeSets.getParamAlignment(i);
231 /// @brief Extract the number of dereferenceable bytes for a call or
232 /// parameter (0=unknown).
233 uint64_t getDereferenceableBytes(unsigned i) const {
234 return AttributeSets.getDereferenceableBytes(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) ||
302 AttributeSets.hasAttribute(2, Attribute::StructRet);
305 /// @brief Determine if the parameter does not alias other parameters.
306 /// @param n The parameter to check. 1 is the first parameter, 0 is the return
307 bool doesNotAlias(unsigned n) const {
308 return AttributeSets.hasAttribute(n, Attribute::NoAlias);
310 void setDoesNotAlias(unsigned n) {
311 addAttribute(n, Attribute::NoAlias);
314 /// @brief Determine if the parameter can be captured.
315 /// @param n The parameter to check. 1 is the first parameter, 0 is the return
316 bool doesNotCapture(unsigned n) const {
317 return AttributeSets.hasAttribute(n, Attribute::NoCapture);
319 void setDoesNotCapture(unsigned n) {
320 addAttribute(n, Attribute::NoCapture);
323 bool doesNotAccessMemory(unsigned n) const {
324 return AttributeSets.hasAttribute(n, Attribute::ReadNone);
326 void setDoesNotAccessMemory(unsigned n) {
327 addAttribute(n, Attribute::ReadNone);
330 bool onlyReadsMemory(unsigned n) const {
331 return doesNotAccessMemory(n) ||
332 AttributeSets.hasAttribute(n, Attribute::ReadOnly);
334 void setOnlyReadsMemory(unsigned n) {
335 addAttribute(n, Attribute::ReadOnly);
338 /// copyAttributesFrom - copy all additional attributes (those not needed to
339 /// create a Function) from the Function Src to this one.
340 void copyAttributesFrom(const GlobalValue *Src) override;
342 /// deleteBody - This method deletes the body of the function, and converts
343 /// the linkage to external.
347 setLinkage(ExternalLinkage);
350 /// removeFromParent - This method unlinks 'this' from the containing module,
351 /// but does not delete it.
353 void removeFromParent() override;
355 /// eraseFromParent - This method unlinks 'this' from the containing module
358 void eraseFromParent() override;
361 /// Get the underlying elements of the Function... the basic block list is
362 /// empty for external functions.
364 const ArgumentListType &getArgumentList() const {
365 CheckLazyArguments();
368 ArgumentListType &getArgumentList() {
369 CheckLazyArguments();
372 static iplist<Argument> Function::*getSublistAccess(Argument*) {
373 return &Function::ArgumentList;
376 const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
377 BasicBlockListType &getBasicBlockList() { return BasicBlocks; }
378 static iplist<BasicBlock> Function::*getSublistAccess(BasicBlock*) {
379 return &Function::BasicBlocks;
382 const BasicBlock &getEntryBlock() const { return front(); }
383 BasicBlock &getEntryBlock() { return front(); }
385 //===--------------------------------------------------------------------===//
386 // Symbol Table Accessing functions...
388 /// getSymbolTable() - Return the symbol table...
390 inline ValueSymbolTable &getValueSymbolTable() { return *SymTab; }
391 inline const ValueSymbolTable &getValueSymbolTable() const { return *SymTab; }
394 //===--------------------------------------------------------------------===//
395 // BasicBlock iterator forwarding functions
397 iterator begin() { return BasicBlocks.begin(); }
398 const_iterator begin() const { return BasicBlocks.begin(); }
399 iterator end () { return BasicBlocks.end(); }
400 const_iterator end () const { return BasicBlocks.end(); }
402 size_t size() const { return BasicBlocks.size(); }
403 bool empty() const { return BasicBlocks.empty(); }
404 const BasicBlock &front() const { return BasicBlocks.front(); }
405 BasicBlock &front() { return BasicBlocks.front(); }
406 const BasicBlock &back() const { return BasicBlocks.back(); }
407 BasicBlock &back() { return BasicBlocks.back(); }
409 /// @name Function Argument Iteration
412 arg_iterator arg_begin() {
413 CheckLazyArguments();
414 return ArgumentList.begin();
416 const_arg_iterator arg_begin() const {
417 CheckLazyArguments();
418 return ArgumentList.begin();
420 arg_iterator arg_end() {
421 CheckLazyArguments();
422 return ArgumentList.end();
424 const_arg_iterator arg_end() const {
425 CheckLazyArguments();
426 return ArgumentList.end();
429 iterator_range<arg_iterator> args() {
430 return iterator_range<arg_iterator>(arg_begin(), arg_end());
433 iterator_range<const_arg_iterator> args() const {
434 return iterator_range<const_arg_iterator>(arg_begin(), arg_end());
439 size_t arg_size() const;
440 bool arg_empty() const;
442 bool hasPrefixData() const {
443 return getSubclassDataFromValue() & (1<<1);
446 Constant *getPrefixData() const;
447 void setPrefixData(Constant *PrefixData);
449 bool hasPrologueData() const {
450 return getSubclassDataFromValue() & (1<<2);
453 Constant *getPrologueData() const;
454 void setPrologueData(Constant *PrologueData);
456 /// Print the function to an output stream with an optional
457 /// AssemblyAnnotationWriter.
458 void print(raw_ostream &OS, AssemblyAnnotationWriter *AAW = nullptr) const;
460 /// viewCFG - This function is meant for use from the debugger. You can just
461 /// say 'call F->viewCFG()' and a ghostview window should pop up from the
462 /// program, displaying the CFG of the current function with the code for each
463 /// basic block inside. This depends on there being a 'dot' and 'gv' program
466 void viewCFG() const;
468 /// viewCFGOnly - This function is meant for use from the debugger. It works
469 /// just like viewCFG, but it does not include the contents of basic blocks
470 /// into the nodes, just the label. If you are only interested in the CFG
471 /// this can make the graph smaller.
473 void viewCFGOnly() const;
475 /// Methods for support type inquiry through isa, cast, and dyn_cast:
476 static inline bool classof(const Value *V) {
477 return V->getValueID() == Value::FunctionVal;
480 /// dropAllReferences() - This method causes all the subinstructions to "let
481 /// go" of all references that they are maintaining. This allows one to
482 /// 'delete' a whole module at a time, even though there may be circular
483 /// references... first all references are dropped, and all use counts go to
484 /// zero. Then everything is deleted for real. Note that no operations are
485 /// valid on an object that has "dropped all references", except operator
488 /// Since no other object in the module can have references into the body of a
489 /// function, dropping all references deletes the entire body of the function,
490 /// including any contained basic blocks.
492 void dropAllReferences();
494 /// hasAddressTaken - returns true if there are any uses of this function
495 /// other than direct calls or invokes to it, or blockaddress expressions.
496 /// Optionally passes back an offending user for diagnostic purposes.
498 bool hasAddressTaken(const User** = nullptr) const;
500 /// isDefTriviallyDead - Return true if it is trivially safe to remove
501 /// this function definition from the module (because it isn't externally
502 /// visible, does not have its address taken, and has no callers). To make
503 /// this more accurate, call removeDeadConstantUsers first.
504 bool isDefTriviallyDead() const;
506 /// callsFunctionThatReturnsTwice - Return true if the function has a call to
507 /// setjmp or other function that gcc recognizes as "returning twice".
508 bool callsFunctionThatReturnsTwice() const;
511 // Shadow Value::setValueSubclassData with a private forwarding method so that
512 // subclasses cannot accidentally use it.
513 void setValueSubclassData(unsigned short D) {
514 Value::setValueSubclassData(D);
518 inline ValueSymbolTable *
519 ilist_traits<BasicBlock>::getSymTab(Function *F) {
520 return F ? &F->getValueSymbolTable() : nullptr;
523 inline ValueSymbolTable *
524 ilist_traits<Argument>::getSymTab(Function *F) {
525 return F ? &F->getValueSymbolTable() : nullptr;
528 } // End llvm namespace