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"
35 // Traits for intrusive list of basic blocks...
36 template<> struct ilist_traits<BasicBlock>
37 : public SymbolTableListTraits<BasicBlock, Function> {
39 // createSentinel is used to get hold of the node that marks the end of the
40 // list... (same trick used here as in ilist_traits<Instruction>)
41 BasicBlock *createSentinel() const {
42 return static_cast<BasicBlock*>(&Sentinel);
44 static void destroySentinel(BasicBlock*) {}
46 BasicBlock *provideInitialHead() const { return createSentinel(); }
47 BasicBlock *ensureHead(BasicBlock*) const { return createSentinel(); }
48 static void noteHead(BasicBlock*, BasicBlock*) {}
50 static ValueSymbolTable *getSymTab(Function *ItemParent);
52 mutable ilist_half_node<BasicBlock> Sentinel;
55 template<> struct ilist_traits<Argument>
56 : public SymbolTableListTraits<Argument, Function> {
58 Argument *createSentinel() const {
59 return static_cast<Argument*>(&Sentinel);
61 static void destroySentinel(Argument*) {}
63 Argument *provideInitialHead() const { return createSentinel(); }
64 Argument *ensureHead(Argument*) const { return createSentinel(); }
65 static void noteHead(Argument*, Argument*) {}
67 static ValueSymbolTable *getSymTab(Function *ItemParent);
69 mutable ilist_half_node<Argument> Sentinel;
72 class Function : public GlobalObject, 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
94 * bit 0 : HasLazyArguments
95 * bit 1 : HasPrefixData
96 * bit 2 : HasPrologueData
97 * bit 3-6: CallingConvention
100 friend class SymbolTableListTraits<Function, Module>;
102 void setParent(Module *parent);
104 /// hasLazyArguments/CheckLazyArguments - The argument list of a function is
105 /// built on demand, so that the list isn't allocated until the first client
106 /// needs it. The hasLazyArguments predicate returns true if the arg list
107 /// hasn't been set up yet.
108 bool hasLazyArguments() const {
109 return getSubclassDataFromValue() & (1<<0);
111 void CheckLazyArguments() const {
112 if (hasLazyArguments())
113 BuildLazyArguments();
115 void BuildLazyArguments() const;
117 Function(const Function&) LLVM_DELETED_FUNCTION;
118 void operator=(const Function&) LLVM_DELETED_FUNCTION;
120 /// Do the actual lookup of an intrinsic ID when the query could not be
121 /// answered from the cache.
122 unsigned lookupIntrinsicID() const LLVM_READONLY;
124 /// Function ctor - If the (optional) Module argument is specified, the
125 /// function is automatically inserted into the end of the function list for
128 Function(FunctionType *Ty, LinkageTypes Linkage,
129 const Twine &N = "", Module *M = nullptr);
132 static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
133 const Twine &N = "", Module *M = nullptr) {
134 return new(0) Function(Ty, Linkage, N, M);
139 Type *getReturnType() const; // Return the type of the ret val
140 FunctionType *getFunctionType() const; // Return the FunctionType for me
142 /// getContext - Return a pointer to the LLVMContext associated with this
143 /// function, or NULL if this function is not bound to a context yet.
144 LLVMContext &getContext() const;
146 /// isVarArg - Return true if this function takes a variable number of
148 bool isVarArg() const;
150 bool isMaterializable() const;
151 void setIsMaterializable(bool V);
153 /// getIntrinsicID - This method returns the ID number of the specified
154 /// function, or Intrinsic::not_intrinsic if the function is not an
155 /// intrinsic, or if the pointer is null. This value is always defined to be
156 /// zero to allow easy checking for whether a function is intrinsic or not.
157 /// The particular intrinsic functions which correspond to this value are
158 /// defined in llvm/Intrinsics.h. Results are cached in the LLVM context,
159 /// subsequent requests for the same ID return results much faster from the
162 unsigned getIntrinsicID() const LLVM_READONLY;
163 bool isIntrinsic() const { return getName().startswith("llvm."); }
165 /// getCallingConv()/setCallingConv(CC) - These method get and set the
166 /// calling convention of this function. The enum values for the known
167 /// calling conventions are defined in CallingConv.h.
168 CallingConv::ID getCallingConv() const {
169 return static_cast<CallingConv::ID>(getSubclassDataFromValue() >> 3);
171 void setCallingConv(CallingConv::ID CC) {
172 setValueSubclassData((getSubclassDataFromValue() & 7) |
173 (static_cast<unsigned>(CC) << 3));
176 /// @brief Return the attribute list for this Function.
177 AttributeSet getAttributes() const { return AttributeSets; }
179 /// @brief Set the attribute list for this Function.
180 void setAttributes(AttributeSet attrs) { AttributeSets = attrs; }
182 /// @brief Add function attributes to this function.
183 void addFnAttr(Attribute::AttrKind N) {
184 setAttributes(AttributeSets.addAttribute(getContext(),
185 AttributeSet::FunctionIndex, N));
188 /// @brief Remove function attributes from this function.
189 void removeFnAttr(Attribute::AttrKind N) {
190 setAttributes(AttributeSets.removeAttribute(
191 getContext(), AttributeSet::FunctionIndex, N));
194 /// @brief Add function attributes to this function.
195 void addFnAttr(StringRef Kind) {
197 AttributeSets.addAttribute(getContext(),
198 AttributeSet::FunctionIndex, Kind));
200 void addFnAttr(StringRef Kind, StringRef Value) {
202 AttributeSets.addAttribute(getContext(),
203 AttributeSet::FunctionIndex, Kind, Value));
206 /// @brief Return true if the function has the attribute.
207 bool hasFnAttribute(Attribute::AttrKind Kind) const {
208 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
210 bool hasFnAttribute(StringRef Kind) const {
211 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
214 /// @brief Return the attribute for the given attribute kind.
215 Attribute getFnAttribute(Attribute::AttrKind Kind) const {
216 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
218 Attribute getFnAttribute(StringRef Kind) const {
219 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
222 /// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
223 /// to use during code generation.
225 const char *getGC() const;
226 void setGC(const char *Str);
229 /// Returns the GCStrategy associated with the specified garbage collector
230 /// algorithm or nullptr if one is not set.
231 GCStrategy *getGCStrategy() const;
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 Extract the alignment for a call or parameter (0=unknown).
243 unsigned getParamAlignment(unsigned i) const {
244 return AttributeSets.getParamAlignment(i);
247 /// @brief Extract the number of dereferenceable bytes for a call or
248 /// parameter (0=unknown).
249 uint64_t getDereferenceableBytes(unsigned i) const {
250 return AttributeSets.getDereferenceableBytes(i);
253 /// @brief Determine if the function does not access memory.
254 bool doesNotAccessMemory() const {
255 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
256 Attribute::ReadNone);
258 void setDoesNotAccessMemory() {
259 addFnAttr(Attribute::ReadNone);
262 /// @brief Determine if the function does not access or only reads memory.
263 bool onlyReadsMemory() const {
264 return doesNotAccessMemory() ||
265 AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
266 Attribute::ReadOnly);
268 void setOnlyReadsMemory() {
269 addFnAttr(Attribute::ReadOnly);
272 /// @brief Determine if the function cannot return.
273 bool doesNotReturn() const {
274 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
275 Attribute::NoReturn);
277 void setDoesNotReturn() {
278 addFnAttr(Attribute::NoReturn);
281 /// @brief Determine if the function cannot unwind.
282 bool doesNotThrow() const {
283 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
284 Attribute::NoUnwind);
286 void setDoesNotThrow() {
287 addFnAttr(Attribute::NoUnwind);
290 /// @brief Determine if the call cannot be duplicated.
291 bool cannotDuplicate() const {
292 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
293 Attribute::NoDuplicate);
295 void setCannotDuplicate() {
296 addFnAttr(Attribute::NoDuplicate);
299 /// @brief True if the ABI mandates (or the user requested) that this
300 /// function be in a unwind table.
301 bool hasUWTable() const {
302 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
305 void setHasUWTable() {
306 addFnAttr(Attribute::UWTable);
309 /// @brief True if this function needs an unwind table.
310 bool needsUnwindTableEntry() const {
311 return hasUWTable() || !doesNotThrow();
314 /// @brief Determine if the function returns a structure through first
315 /// pointer argument.
316 bool hasStructRetAttr() const {
317 return AttributeSets.hasAttribute(1, Attribute::StructRet) ||
318 AttributeSets.hasAttribute(2, Attribute::StructRet);
321 /// @brief Determine if the parameter does not alias other parameters.
322 /// @param n The parameter to check. 1 is the first parameter, 0 is the return
323 bool doesNotAlias(unsigned n) const {
324 return AttributeSets.hasAttribute(n, Attribute::NoAlias);
326 void setDoesNotAlias(unsigned n) {
327 addAttribute(n, Attribute::NoAlias);
330 /// @brief Determine if the parameter can be captured.
331 /// @param n The parameter to check. 1 is the first parameter, 0 is the return
332 bool doesNotCapture(unsigned n) const {
333 return AttributeSets.hasAttribute(n, Attribute::NoCapture);
335 void setDoesNotCapture(unsigned n) {
336 addAttribute(n, Attribute::NoCapture);
339 bool doesNotAccessMemory(unsigned n) const {
340 return AttributeSets.hasAttribute(n, Attribute::ReadNone);
342 void setDoesNotAccessMemory(unsigned n) {
343 addAttribute(n, Attribute::ReadNone);
346 bool onlyReadsMemory(unsigned n) const {
347 return doesNotAccessMemory(n) ||
348 AttributeSets.hasAttribute(n, Attribute::ReadOnly);
350 void setOnlyReadsMemory(unsigned n) {
351 addAttribute(n, Attribute::ReadOnly);
354 /// copyAttributesFrom - copy all additional attributes (those not needed to
355 /// create a Function) from the Function Src to this one.
356 void copyAttributesFrom(const GlobalValue *Src) override;
358 /// deleteBody - This method deletes the body of the function, and converts
359 /// the linkage to external.
363 setLinkage(ExternalLinkage);
366 /// removeFromParent - This method unlinks 'this' from the containing module,
367 /// but does not delete it.
369 void removeFromParent() override;
371 /// eraseFromParent - This method unlinks 'this' from the containing module
374 void eraseFromParent() override;
377 /// Get the underlying elements of the Function... the basic block list is
378 /// empty for external functions.
380 const ArgumentListType &getArgumentList() const {
381 CheckLazyArguments();
384 ArgumentListType &getArgumentList() {
385 CheckLazyArguments();
388 static iplist<Argument> Function::*getSublistAccess(Argument*) {
389 return &Function::ArgumentList;
392 const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
393 BasicBlockListType &getBasicBlockList() { return BasicBlocks; }
394 static iplist<BasicBlock> Function::*getSublistAccess(BasicBlock*) {
395 return &Function::BasicBlocks;
398 const BasicBlock &getEntryBlock() const { return front(); }
399 BasicBlock &getEntryBlock() { return front(); }
401 //===--------------------------------------------------------------------===//
402 // Symbol Table Accessing functions...
404 /// getSymbolTable() - Return the symbol table...
406 inline ValueSymbolTable &getValueSymbolTable() { return *SymTab; }
407 inline const ValueSymbolTable &getValueSymbolTable() const { return *SymTab; }
410 //===--------------------------------------------------------------------===//
411 // BasicBlock iterator forwarding functions
413 iterator begin() { return BasicBlocks.begin(); }
414 const_iterator begin() const { return BasicBlocks.begin(); }
415 iterator end () { return BasicBlocks.end(); }
416 const_iterator end () const { return BasicBlocks.end(); }
418 size_t size() const { return BasicBlocks.size(); }
419 bool empty() const { return BasicBlocks.empty(); }
420 const BasicBlock &front() const { return BasicBlocks.front(); }
421 BasicBlock &front() { return BasicBlocks.front(); }
422 const BasicBlock &back() const { return BasicBlocks.back(); }
423 BasicBlock &back() { return BasicBlocks.back(); }
425 /// @name Function Argument Iteration
428 arg_iterator arg_begin() {
429 CheckLazyArguments();
430 return ArgumentList.begin();
432 const_arg_iterator arg_begin() const {
433 CheckLazyArguments();
434 return ArgumentList.begin();
436 arg_iterator arg_end() {
437 CheckLazyArguments();
438 return ArgumentList.end();
440 const_arg_iterator arg_end() const {
441 CheckLazyArguments();
442 return ArgumentList.end();
445 iterator_range<arg_iterator> args() {
446 return iterator_range<arg_iterator>(arg_begin(), arg_end());
449 iterator_range<const_arg_iterator> args() const {
450 return iterator_range<const_arg_iterator>(arg_begin(), arg_end());
455 size_t arg_size() const;
456 bool arg_empty() const;
458 bool hasPrefixData() const {
459 return getSubclassDataFromValue() & (1<<1);
462 Constant *getPrefixData() const;
463 void setPrefixData(Constant *PrefixData);
465 bool hasPrologueData() const {
466 return getSubclassDataFromValue() & (1<<2);
469 Constant *getPrologueData() const;
470 void setPrologueData(Constant *PrologueData);
472 /// viewCFG - This function is meant for use from the debugger. You can just
473 /// say 'call F->viewCFG()' and a ghostview window should pop up from the
474 /// program, displaying the CFG of the current function with the code for each
475 /// basic block inside. This depends on there being a 'dot' and 'gv' program
478 void viewCFG() const;
480 /// viewCFGOnly - This function is meant for use from the debugger. It works
481 /// just like viewCFG, but it does not include the contents of basic blocks
482 /// into the nodes, just the label. If you are only interested in the CFG
483 /// this can make the graph smaller.
485 void viewCFGOnly() const;
487 /// Methods for support type inquiry through isa, cast, and dyn_cast:
488 static inline bool classof(const Value *V) {
489 return V->getValueID() == Value::FunctionVal;
492 /// dropAllReferences() - This method causes all the subinstructions to "let
493 /// go" of all references that they are maintaining. This allows one to
494 /// 'delete' a whole module at a time, even though there may be circular
495 /// references... first all references are dropped, and all use counts go to
496 /// zero. Then everything is deleted for real. Note that no operations are
497 /// valid on an object that has "dropped all references", except operator
500 /// Since no other object in the module can have references into the body of a
501 /// function, dropping all references deletes the entire body of the function,
502 /// including any contained basic blocks.
504 void dropAllReferences();
506 /// hasAddressTaken - returns true if there are any uses of this function
507 /// other than direct calls or invokes to it, or blockaddress expressions.
508 /// Optionally passes back an offending user for diagnostic purposes.
510 bool hasAddressTaken(const User** = nullptr) const;
512 /// isDefTriviallyDead - Return true if it is trivially safe to remove
513 /// this function definition from the module (because it isn't externally
514 /// visible, does not have its address taken, and has no callers). To make
515 /// this more accurate, call removeDeadConstantUsers first.
516 bool isDefTriviallyDead() const;
518 /// callsFunctionThatReturnsTwice - Return true if the function has a call to
519 /// setjmp or other function that gcc recognizes as "returning twice".
520 bool callsFunctionThatReturnsTwice() const;
523 // Shadow Value::setValueSubclassData with a private forwarding method so that
524 // subclasses cannot accidentally use it.
525 void setValueSubclassData(unsigned short D) {
526 Value::setValueSubclassData(D);
530 inline ValueSymbolTable *
531 ilist_traits<BasicBlock>::getSymTab(Function *F) {
532 return F ? &F->getValueSymbolTable() : nullptr;
535 inline ValueSymbolTable *
536 ilist_traits<Argument>::getSymTab(Function *F) {
537 return F ? &F->getValueSymbolTable() : nullptr;
540 } // End llvm namespace