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
93 * bit 0 : HasLazyArguments
94 * bit 1 : HasPrefixData
95 * bit 2 : HasPrologueData
96 * bit 3-6: CallingConvention
99 friend class SymbolTableListTraits<Function, Module>;
101 void setParent(Module *parent);
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);
110 void CheckLazyArguments() const {
111 if (hasLazyArguments())
112 BuildLazyArguments();
114 void BuildLazyArguments() const;
116 Function(const Function&) = delete;
117 void operator=(const Function&) = delete;
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;
123 /// Function ctor - If the (optional) Module argument is specified, the
124 /// function is automatically inserted into the end of the function list for
127 Function(FunctionType *Ty, LinkageTypes Linkage,
128 const Twine &N = "", Module *M = nullptr);
131 static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
132 const Twine &N = "", Module *M = nullptr) {
133 return new(0) Function(Ty, Linkage, N, M);
138 Type *getReturnType() const; // Return the type of the ret val
139 FunctionType *getFunctionType() const; // Return the FunctionType for me
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;
145 /// isVarArg - Return true if this function takes a variable number of
147 bool isVarArg() const;
149 bool isMaterializable() const;
150 void setIsMaterializable(bool V);
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
161 unsigned getIntrinsicID() const LLVM_READONLY;
162 bool isIntrinsic() const { return getName().startswith("llvm."); }
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);
170 void setCallingConv(CallingConv::ID CC) {
171 setValueSubclassData((getSubclassDataFromValue() & 7) |
172 (static_cast<unsigned>(CC) << 3));
175 /// @brief Return the attribute list for this Function.
176 AttributeSet getAttributes() const { return AttributeSets; }
178 /// @brief Set the attribute list for this Function.
179 void setAttributes(AttributeSet attrs) { AttributeSets = attrs; }
181 /// @brief Add function attributes to this function.
182 void addFnAttr(Attribute::AttrKind N) {
183 setAttributes(AttributeSets.addAttribute(getContext(),
184 AttributeSet::FunctionIndex, N));
187 /// @brief Remove function attributes from this function.
188 void removeFnAttr(Attribute::AttrKind N) {
189 setAttributes(AttributeSets.removeAttribute(
190 getContext(), AttributeSet::FunctionIndex, N));
193 /// @brief Add function attributes to this function.
194 void addFnAttr(StringRef Kind) {
196 AttributeSets.addAttribute(getContext(),
197 AttributeSet::FunctionIndex, Kind));
199 void addFnAttr(StringRef Kind, StringRef Value) {
201 AttributeSets.addAttribute(getContext(),
202 AttributeSet::FunctionIndex, Kind, Value));
205 /// @brief Return true if the function has the attribute.
206 bool hasFnAttribute(Attribute::AttrKind Kind) const {
207 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
209 bool hasFnAttribute(StringRef Kind) const {
210 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
213 /// @brief Return the attribute for the given attribute kind.
214 Attribute getFnAttribute(Attribute::AttrKind Kind) const {
215 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
217 Attribute getFnAttribute(StringRef Kind) const {
218 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
221 /// \brief Return the stack alignment for the function.
222 unsigned getFnStackAlignment() const {
223 return AttributeSets.getStackAlignment(AttributeSet::FunctionIndex);
226 /// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
227 /// to use during code generation.
229 const char *getGC() const;
230 void setGC(const char *Str);
233 /// @brief adds the attribute to the list of attributes.
234 void addAttribute(unsigned i, Attribute::AttrKind attr);
236 /// @brief adds the attributes to the list of attributes.
237 void addAttributes(unsigned i, AttributeSet attrs);
239 /// @brief removes the attributes from the list of attributes.
240 void removeAttributes(unsigned i, AttributeSet attr);
242 /// @brief adds the dereferenceable attribute to the list of attributes.
243 void addDereferenceableAttr(unsigned i, uint64_t Bytes);
245 /// @brief Extract the alignment for a call or parameter (0=unknown).
246 unsigned getParamAlignment(unsigned i) const {
247 return AttributeSets.getParamAlignment(i);
250 /// @brief Extract the number of dereferenceable bytes for a call or
251 /// parameter (0=unknown).
252 uint64_t getDereferenceableBytes(unsigned i) const {
253 return AttributeSets.getDereferenceableBytes(i);
256 /// @brief Determine if the function does not access memory.
257 bool doesNotAccessMemory() const {
258 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
259 Attribute::ReadNone);
261 void setDoesNotAccessMemory() {
262 addFnAttr(Attribute::ReadNone);
265 /// @brief Determine if the function does not access or only reads memory.
266 bool onlyReadsMemory() const {
267 return doesNotAccessMemory() ||
268 AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
269 Attribute::ReadOnly);
271 void setOnlyReadsMemory() {
272 addFnAttr(Attribute::ReadOnly);
275 /// @brief Determine if the function cannot return.
276 bool doesNotReturn() const {
277 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
278 Attribute::NoReturn);
280 void setDoesNotReturn() {
281 addFnAttr(Attribute::NoReturn);
284 /// @brief Determine if the function cannot unwind.
285 bool doesNotThrow() const {
286 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
287 Attribute::NoUnwind);
289 void setDoesNotThrow() {
290 addFnAttr(Attribute::NoUnwind);
293 /// @brief Determine if the call cannot be duplicated.
294 bool cannotDuplicate() const {
295 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
296 Attribute::NoDuplicate);
298 void setCannotDuplicate() {
299 addFnAttr(Attribute::NoDuplicate);
302 /// @brief True if the ABI mandates (or the user requested) that this
303 /// function be in a unwind table.
304 bool hasUWTable() const {
305 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
308 void setHasUWTable() {
309 addFnAttr(Attribute::UWTable);
312 /// @brief True if this function needs an unwind table.
313 bool needsUnwindTableEntry() const {
314 return hasUWTable() || !doesNotThrow();
317 /// @brief Determine if the function returns a structure through first
318 /// pointer argument.
319 bool hasStructRetAttr() const {
320 return AttributeSets.hasAttribute(1, Attribute::StructRet) ||
321 AttributeSets.hasAttribute(2, Attribute::StructRet);
324 /// @brief Determine if the parameter does not alias other parameters.
325 /// @param n The parameter to check. 1 is the first parameter, 0 is the return
326 bool doesNotAlias(unsigned n) const {
327 return AttributeSets.hasAttribute(n, Attribute::NoAlias);
329 void setDoesNotAlias(unsigned n) {
330 addAttribute(n, Attribute::NoAlias);
333 /// @brief Determine if the parameter can be captured.
334 /// @param n The parameter to check. 1 is the first parameter, 0 is the return
335 bool doesNotCapture(unsigned n) const {
336 return AttributeSets.hasAttribute(n, Attribute::NoCapture);
338 void setDoesNotCapture(unsigned n) {
339 addAttribute(n, Attribute::NoCapture);
342 bool doesNotAccessMemory(unsigned n) const {
343 return AttributeSets.hasAttribute(n, Attribute::ReadNone);
345 void setDoesNotAccessMemory(unsigned n) {
346 addAttribute(n, Attribute::ReadNone);
349 bool onlyReadsMemory(unsigned n) const {
350 return doesNotAccessMemory(n) ||
351 AttributeSets.hasAttribute(n, Attribute::ReadOnly);
353 void setOnlyReadsMemory(unsigned n) {
354 addAttribute(n, Attribute::ReadOnly);
357 /// copyAttributesFrom - copy all additional attributes (those not needed to
358 /// create a Function) from the Function Src to this one.
359 void copyAttributesFrom(const GlobalValue *Src) override;
361 /// deleteBody - This method deletes the body of the function, and converts
362 /// the linkage to external.
366 setLinkage(ExternalLinkage);
369 /// removeFromParent - This method unlinks 'this' from the containing module,
370 /// but does not delete it.
372 void removeFromParent() override;
374 /// eraseFromParent - This method unlinks 'this' from the containing module
377 void eraseFromParent() override;
380 /// Get the underlying elements of the Function... the basic block list is
381 /// empty for external functions.
383 const ArgumentListType &getArgumentList() const {
384 CheckLazyArguments();
387 ArgumentListType &getArgumentList() {
388 CheckLazyArguments();
391 static iplist<Argument> Function::*getSublistAccess(Argument*) {
392 return &Function::ArgumentList;
395 const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
396 BasicBlockListType &getBasicBlockList() { return BasicBlocks; }
397 static iplist<BasicBlock> Function::*getSublistAccess(BasicBlock*) {
398 return &Function::BasicBlocks;
401 const BasicBlock &getEntryBlock() const { return front(); }
402 BasicBlock &getEntryBlock() { return front(); }
404 //===--------------------------------------------------------------------===//
405 // Symbol Table Accessing functions...
407 /// getSymbolTable() - Return the symbol table...
409 inline ValueSymbolTable &getValueSymbolTable() { return *SymTab; }
410 inline const ValueSymbolTable &getValueSymbolTable() const { return *SymTab; }
413 //===--------------------------------------------------------------------===//
414 // BasicBlock iterator forwarding functions
416 iterator begin() { return BasicBlocks.begin(); }
417 const_iterator begin() const { return BasicBlocks.begin(); }
418 iterator end () { return BasicBlocks.end(); }
419 const_iterator end () const { return BasicBlocks.end(); }
421 size_t size() const { return BasicBlocks.size(); }
422 bool empty() const { return BasicBlocks.empty(); }
423 const BasicBlock &front() const { return BasicBlocks.front(); }
424 BasicBlock &front() { return BasicBlocks.front(); }
425 const BasicBlock &back() const { return BasicBlocks.back(); }
426 BasicBlock &back() { return BasicBlocks.back(); }
428 /// @name Function Argument Iteration
431 arg_iterator arg_begin() {
432 CheckLazyArguments();
433 return ArgumentList.begin();
435 const_arg_iterator arg_begin() const {
436 CheckLazyArguments();
437 return ArgumentList.begin();
439 arg_iterator arg_end() {
440 CheckLazyArguments();
441 return ArgumentList.end();
443 const_arg_iterator arg_end() const {
444 CheckLazyArguments();
445 return ArgumentList.end();
448 iterator_range<arg_iterator> args() {
449 return iterator_range<arg_iterator>(arg_begin(), arg_end());
452 iterator_range<const_arg_iterator> args() const {
453 return iterator_range<const_arg_iterator>(arg_begin(), arg_end());
458 size_t arg_size() const;
459 bool arg_empty() const;
461 bool hasPrefixData() const {
462 return getSubclassDataFromValue() & (1<<1);
465 Constant *getPrefixData() const;
466 void setPrefixData(Constant *PrefixData);
468 bool hasPrologueData() const {
469 return getSubclassDataFromValue() & (1<<2);
472 Constant *getPrologueData() const;
473 void setPrologueData(Constant *PrologueData);
475 /// viewCFG - This function is meant for use from the debugger. You can just
476 /// say 'call F->viewCFG()' and a ghostview window should pop up from the
477 /// program, displaying the CFG of the current function with the code for each
478 /// basic block inside. This depends on there being a 'dot' and 'gv' program
481 void viewCFG() const;
483 /// viewCFGOnly - This function is meant for use from the debugger. It works
484 /// just like viewCFG, but it does not include the contents of basic blocks
485 /// into the nodes, just the label. If you are only interested in the CFG
486 /// this can make the graph smaller.
488 void viewCFGOnly() const;
490 /// Methods for support type inquiry through isa, cast, and dyn_cast:
491 static inline bool classof(const Value *V) {
492 return V->getValueID() == Value::FunctionVal;
495 /// dropAllReferences() - This method causes all the subinstructions to "let
496 /// go" of all references that they are maintaining. This allows one to
497 /// 'delete' a whole module at a time, even though there may be circular
498 /// references... first all references are dropped, and all use counts go to
499 /// zero. Then everything is deleted for real. Note that no operations are
500 /// valid on an object that has "dropped all references", except operator
503 /// Since no other object in the module can have references into the body of a
504 /// function, dropping all references deletes the entire body of the function,
505 /// including any contained basic blocks.
507 void dropAllReferences();
509 /// hasAddressTaken - returns true if there are any uses of this function
510 /// other than direct calls or invokes to it, or blockaddress expressions.
511 /// Optionally passes back an offending user for diagnostic purposes.
513 bool hasAddressTaken(const User** = nullptr) const;
515 /// isDefTriviallyDead - Return true if it is trivially safe to remove
516 /// this function definition from the module (because it isn't externally
517 /// visible, does not have its address taken, and has no callers). To make
518 /// this more accurate, call removeDeadConstantUsers first.
519 bool isDefTriviallyDead() const;
521 /// callsFunctionThatReturnsTwice - Return true if the function has a call to
522 /// setjmp or other function that gcc recognizes as "returning twice".
523 bool callsFunctionThatReturnsTwice() const;
526 // Shadow Value::setValueSubclassData with a private forwarding method so that
527 // subclasses cannot accidentally use it.
528 void setValueSubclassData(unsigned short D) {
529 Value::setValueSubclassData(D);
533 inline ValueSymbolTable *
534 ilist_traits<BasicBlock>::getSymTab(Function *F) {
535 return F ? &F->getValueSymbolTable() : nullptr;
538 inline ValueSymbolTable *
539 ilist_traits<Argument>::getSymTab(Function *F) {
540 return F ? &F->getValueSymbolTable() : nullptr;
543 } // End llvm namespace