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/ADT/Optional.h"
23 #include "llvm/IR/Argument.h"
24 #include "llvm/IR/Attributes.h"
25 #include "llvm/IR/BasicBlock.h"
26 #include "llvm/IR/CallingConv.h"
27 #include "llvm/IR/GlobalObject.h"
28 #include "llvm/IR/OperandTraits.h"
29 #include "llvm/Support/Compiler.h"
37 template<> struct ilist_traits<Argument>
38 : public SymbolTableListTraits<Argument, Function> {
40 Argument *createSentinel() const {
41 return static_cast<Argument*>(&Sentinel);
43 static void destroySentinel(Argument*) {}
45 Argument *provideInitialHead() const { return createSentinel(); }
46 Argument *ensureHead(Argument*) const { return createSentinel(); }
47 static void noteHead(Argument*, Argument*) {}
49 static ValueSymbolTable *getSymTab(Function *ItemParent);
52 mutable ilist_half_node<Argument> Sentinel;
55 class Function : public GlobalObject, public ilist_node<Function> {
57 typedef iplist<Argument> ArgumentListType;
58 typedef iplist<BasicBlock> BasicBlockListType;
60 // BasicBlock iterators...
61 typedef BasicBlockListType::iterator iterator;
62 typedef BasicBlockListType::const_iterator const_iterator;
64 typedef ArgumentListType::iterator arg_iterator;
65 typedef ArgumentListType::const_iterator const_arg_iterator;
68 // Important things that make up a function!
69 BasicBlockListType BasicBlocks; ///< The basic blocks
70 mutable ArgumentListType ArgumentList; ///< The formal arguments
71 ValueSymbolTable *SymTab; ///< Symbol table of args/instructions
72 AttributeSet AttributeSets; ///< Parameter attributes
78 * bit 0 : HasLazyArguments
79 * bit 1 : HasPrefixData
80 * bit 2 : HasPrologueData
81 * bit 3-6: CallingConvention
84 /// Bits from GlobalObject::GlobalObjectSubclassData.
86 /// Whether this function is materializable.
87 IsMaterializableBit = 1 << 0,
88 HasMetadataHashEntryBit = 1 << 1
90 void setGlobalObjectBit(unsigned Mask, bool Value) {
91 setGlobalObjectSubClassData((~Mask & getGlobalObjectSubClassData()) |
95 friend class SymbolTableListTraits<Function, Module>;
97 void setParent(Module *parent);
99 /// hasLazyArguments/CheckLazyArguments - The argument list of a function is
100 /// built on demand, so that the list isn't allocated until the first client
101 /// needs it. The hasLazyArguments predicate returns true if the arg list
102 /// hasn't been set up yet.
103 bool hasLazyArguments() const {
104 return getSubclassDataFromValue() & (1<<0);
106 void CheckLazyArguments() const {
107 if (hasLazyArguments())
108 BuildLazyArguments();
110 void BuildLazyArguments() const;
112 Function(const Function&) = delete;
113 void operator=(const Function&) = delete;
115 /// Function ctor - If the (optional) Module argument is specified, the
116 /// function is automatically inserted into the end of the function list for
119 Function(FunctionType *Ty, LinkageTypes Linkage,
120 const Twine &N = "", Module *M = nullptr);
123 static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
124 const Twine &N = "", Module *M = nullptr) {
125 return new(1) Function(Ty, Linkage, N, M);
128 ~Function() override;
130 /// \brief Provide fast operand accessors
131 DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
133 /// \brief Get the personality function associated with this function.
134 bool hasPersonalityFn() const { return getNumOperands() != 0; }
135 Constant *getPersonalityFn() const {
136 assert(hasPersonalityFn());
137 return cast<Constant>(Op<0>());
139 void setPersonalityFn(Constant *C);
141 Type *getReturnType() const; // Return the type of the ret val
142 FunctionType *getFunctionType() const; // Return the FunctionType for me
144 /// getContext - Return a reference to the LLVMContext associated with this
146 LLVMContext &getContext() const;
148 /// isVarArg - Return true if this function takes a variable number of
150 bool isVarArg() const;
152 bool isMaterializable() const;
153 void setIsMaterializable(bool V);
155 /// getIntrinsicID - This method returns the ID number of the specified
156 /// function, or Intrinsic::not_intrinsic if the function is not an
157 /// intrinsic, or if the pointer is null. This value is always defined to be
158 /// zero to allow easy checking for whether a function is intrinsic or not.
159 /// The particular intrinsic functions which correspond to this value are
160 /// defined in llvm/Intrinsics.h.
161 Intrinsic::ID getIntrinsicID() const LLVM_READONLY { return IntID; }
162 bool isIntrinsic() const { return getName().startswith("llvm."); }
164 /// \brief Recalculate the ID for this function if it is an Intrinsic defined
165 /// in llvm/Intrinsics.h. Sets the intrinsic ID to Intrinsic::not_intrinsic
166 /// if the name of this function does not match an intrinsic in that header.
167 /// Note, this method does not need to be called directly, as it is called
168 /// from Value::setName() whenever the name of this function changes.
169 void recalculateIntrinsicID();
171 /// getCallingConv()/setCallingConv(CC) - These method get and set the
172 /// calling convention of this function. The enum values for the known
173 /// calling conventions are defined in CallingConv.h.
174 CallingConv::ID getCallingConv() const {
175 return static_cast<CallingConv::ID>(getSubclassDataFromValue() >> 3);
177 void setCallingConv(CallingConv::ID CC) {
178 setValueSubclassData((getSubclassDataFromValue() & 7) |
179 (static_cast<unsigned>(CC) << 3));
182 /// @brief Return the attribute list for this Function.
183 AttributeSet getAttributes() const { return AttributeSets; }
185 /// @brief Set the attribute list for this Function.
186 void setAttributes(AttributeSet attrs) { AttributeSets = attrs; }
188 /// @brief Add function attributes to this function.
189 void addFnAttr(Attribute::AttrKind N) {
190 setAttributes(AttributeSets.addAttribute(getContext(),
191 AttributeSet::FunctionIndex, N));
194 /// @brief Remove function attributes from this function.
195 void removeFnAttr(Attribute::AttrKind N) {
196 setAttributes(AttributeSets.removeAttribute(
197 getContext(), AttributeSet::FunctionIndex, N));
200 /// @brief Add function attributes to this function.
201 void addFnAttr(StringRef Kind) {
203 AttributeSets.addAttribute(getContext(),
204 AttributeSet::FunctionIndex, Kind));
206 void addFnAttr(StringRef Kind, StringRef Value) {
208 AttributeSets.addAttribute(getContext(),
209 AttributeSet::FunctionIndex, Kind, Value));
212 /// Set the entry count for this function.
213 void setEntryCount(uint64_t Count);
215 /// Get the entry count for this function.
216 Optional<uint64_t> getEntryCount() const;
218 /// @brief Return true if the function has the attribute.
219 bool hasFnAttribute(Attribute::AttrKind Kind) const {
220 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
222 bool hasFnAttribute(StringRef Kind) const {
223 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
226 /// @brief Return the attribute for the given attribute kind.
227 Attribute getFnAttribute(Attribute::AttrKind Kind) const {
228 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
230 Attribute getFnAttribute(StringRef Kind) const {
231 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
234 /// \brief Return the stack alignment for the function.
235 unsigned getFnStackAlignment() const {
236 return AttributeSets.getStackAlignment(AttributeSet::FunctionIndex);
239 /// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
240 /// to use during code generation.
242 const char *getGC() const;
243 void setGC(const char *Str);
246 /// @brief adds the attribute to the list of attributes.
247 void addAttribute(unsigned i, Attribute::AttrKind attr);
249 /// @brief adds the attributes to the list of attributes.
250 void addAttributes(unsigned i, AttributeSet attrs);
252 /// @brief removes the attributes from the list of attributes.
253 void removeAttributes(unsigned i, AttributeSet attr);
255 /// @brief adds the dereferenceable attribute to the list of attributes.
256 void addDereferenceableAttr(unsigned i, uint64_t Bytes);
258 /// @brief adds the dereferenceable_or_null attribute to the list of
260 void addDereferenceableOrNullAttr(unsigned i, uint64_t Bytes);
262 /// @brief Extract the alignment for a call or parameter (0=unknown).
263 unsigned getParamAlignment(unsigned i) const {
264 return AttributeSets.getParamAlignment(i);
267 /// @brief Extract the number of dereferenceable bytes for a call or
268 /// parameter (0=unknown).
269 uint64_t getDereferenceableBytes(unsigned i) const {
270 return AttributeSets.getDereferenceableBytes(i);
273 /// @brief Extract the number of dereferenceable_or_null bytes for a call or
274 /// parameter (0=unknown).
275 uint64_t getDereferenceableOrNullBytes(unsigned i) const {
276 return AttributeSets.getDereferenceableOrNullBytes(i);
279 /// @brief Determine if the function does not access memory.
280 bool doesNotAccessMemory() const {
281 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
282 Attribute::ReadNone);
284 void setDoesNotAccessMemory() {
285 addFnAttr(Attribute::ReadNone);
288 /// @brief Determine if the function does not access or only reads memory.
289 bool onlyReadsMemory() const {
290 return doesNotAccessMemory() ||
291 AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
292 Attribute::ReadOnly);
294 void setOnlyReadsMemory() {
295 addFnAttr(Attribute::ReadOnly);
298 /// @brief Determine if the call can access memmory only using pointers based
299 /// on its arguments.
300 bool onlyAccessesArgMemory() const {
301 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
302 Attribute::ArgMemOnly);
304 void setOnlyAccessesArgMemory() { addFnAttr(Attribute::ArgMemOnly); }
306 /// @brief Determine if the function cannot return.
307 bool doesNotReturn() const {
308 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
309 Attribute::NoReturn);
311 void setDoesNotReturn() {
312 addFnAttr(Attribute::NoReturn);
315 /// @brief Determine if the function cannot unwind.
316 bool doesNotThrow() const {
317 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
318 Attribute::NoUnwind);
320 void setDoesNotThrow() {
321 addFnAttr(Attribute::NoUnwind);
324 /// @brief Determine if the call cannot be duplicated.
325 bool cannotDuplicate() const {
326 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
327 Attribute::NoDuplicate);
329 void setCannotDuplicate() {
330 addFnAttr(Attribute::NoDuplicate);
333 /// @brief Determine if the call is convergent.
334 bool isConvergent() const {
335 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
336 Attribute::Convergent);
338 void setConvergent() {
339 addFnAttr(Attribute::Convergent);
343 /// @brief True if the ABI mandates (or the user requested) that this
344 /// function be in a unwind table.
345 bool hasUWTable() const {
346 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
349 void setHasUWTable() {
350 addFnAttr(Attribute::UWTable);
353 /// @brief True if this function needs an unwind table.
354 bool needsUnwindTableEntry() const {
355 return hasUWTable() || !doesNotThrow();
358 /// @brief Determine if the function returns a structure through first
359 /// pointer argument.
360 bool hasStructRetAttr() const {
361 return AttributeSets.hasAttribute(1, Attribute::StructRet) ||
362 AttributeSets.hasAttribute(2, Attribute::StructRet);
365 /// @brief Determine if the parameter does not alias other parameters.
366 /// @param n The parameter to check. 1 is the first parameter, 0 is the return
367 bool doesNotAlias(unsigned n) const {
368 return AttributeSets.hasAttribute(n, Attribute::NoAlias);
370 void setDoesNotAlias(unsigned n) {
371 addAttribute(n, Attribute::NoAlias);
374 /// @brief Determine if the parameter can be captured.
375 /// @param n The parameter to check. 1 is the first parameter, 0 is the return
376 bool doesNotCapture(unsigned n) const {
377 return AttributeSets.hasAttribute(n, Attribute::NoCapture);
379 void setDoesNotCapture(unsigned n) {
380 addAttribute(n, Attribute::NoCapture);
383 bool doesNotAccessMemory(unsigned n) const {
384 return AttributeSets.hasAttribute(n, Attribute::ReadNone);
386 void setDoesNotAccessMemory(unsigned n) {
387 addAttribute(n, Attribute::ReadNone);
390 bool onlyReadsMemory(unsigned n) const {
391 return doesNotAccessMemory(n) ||
392 AttributeSets.hasAttribute(n, Attribute::ReadOnly);
394 void setOnlyReadsMemory(unsigned n) {
395 addAttribute(n, Attribute::ReadOnly);
398 /// Optimize this function for minimum size (-Oz).
399 bool optForMinSize() const { return hasFnAttribute(Attribute::MinSize); };
401 /// Optimize this function for size (-Os) or minimum size (-Oz).
402 bool optForSize() const {
403 return hasFnAttribute(Attribute::OptimizeForSize) || optForMinSize();
406 /// copyAttributesFrom - copy all additional attributes (those not needed to
407 /// create a Function) from the Function Src to this one.
408 void copyAttributesFrom(const GlobalValue *Src) override;
410 /// deleteBody - This method deletes the body of the function, and converts
411 /// the linkage to external.
415 setLinkage(ExternalLinkage);
418 /// removeFromParent - This method unlinks 'this' from the containing module,
419 /// but does not delete it.
421 void removeFromParent() override;
423 /// eraseFromParent - This method unlinks 'this' from the containing module
426 void eraseFromParent() override;
428 /// Get the underlying elements of the Function... the basic block list is
429 /// empty for external functions.
431 const ArgumentListType &getArgumentList() const {
432 CheckLazyArguments();
435 ArgumentListType &getArgumentList() {
436 CheckLazyArguments();
439 static iplist<Argument> Function::*getSublistAccess(Argument*) {
440 return &Function::ArgumentList;
443 const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
444 BasicBlockListType &getBasicBlockList() { return BasicBlocks; }
445 static iplist<BasicBlock> Function::*getSublistAccess(BasicBlock*) {
446 return &Function::BasicBlocks;
449 const BasicBlock &getEntryBlock() const { return front(); }
450 BasicBlock &getEntryBlock() { return front(); }
452 //===--------------------------------------------------------------------===//
453 // Symbol Table Accessing functions...
455 /// getSymbolTable() - Return the symbol table...
457 inline ValueSymbolTable &getValueSymbolTable() { return *SymTab; }
458 inline const ValueSymbolTable &getValueSymbolTable() const { return *SymTab; }
460 //===--------------------------------------------------------------------===//
461 // BasicBlock iterator forwarding functions
463 iterator begin() { return BasicBlocks.begin(); }
464 const_iterator begin() const { return BasicBlocks.begin(); }
465 iterator end () { return BasicBlocks.end(); }
466 const_iterator end () const { return BasicBlocks.end(); }
468 size_t size() const { return BasicBlocks.size(); }
469 bool empty() const { return BasicBlocks.empty(); }
470 const BasicBlock &front() const { return BasicBlocks.front(); }
471 BasicBlock &front() { return BasicBlocks.front(); }
472 const BasicBlock &back() const { return BasicBlocks.back(); }
473 BasicBlock &back() { return BasicBlocks.back(); }
475 /// @name Function Argument Iteration
478 arg_iterator arg_begin() {
479 CheckLazyArguments();
480 return ArgumentList.begin();
482 const_arg_iterator arg_begin() const {
483 CheckLazyArguments();
484 return ArgumentList.begin();
486 arg_iterator arg_end() {
487 CheckLazyArguments();
488 return ArgumentList.end();
490 const_arg_iterator arg_end() const {
491 CheckLazyArguments();
492 return ArgumentList.end();
495 iterator_range<arg_iterator> args() {
496 return iterator_range<arg_iterator>(arg_begin(), arg_end());
499 iterator_range<const_arg_iterator> args() const {
500 return iterator_range<const_arg_iterator>(arg_begin(), arg_end());
505 size_t arg_size() const;
506 bool arg_empty() const;
508 bool hasPrefixData() const {
509 return getSubclassDataFromValue() & (1<<1);
512 Constant *getPrefixData() const;
513 void setPrefixData(Constant *PrefixData);
515 bool hasPrologueData() const {
516 return getSubclassDataFromValue() & (1<<2);
519 Constant *getPrologueData() const;
520 void setPrologueData(Constant *PrologueData);
522 /// viewCFG - This function is meant for use from the debugger. You can just
523 /// say 'call F->viewCFG()' and a ghostview window should pop up from the
524 /// program, displaying the CFG of the current function with the code for each
525 /// basic block inside. This depends on there being a 'dot' and 'gv' program
528 void viewCFG() const;
530 /// viewCFGOnly - This function is meant for use from the debugger. It works
531 /// just like viewCFG, but it does not include the contents of basic blocks
532 /// into the nodes, just the label. If you are only interested in the CFG
533 /// this can make the graph smaller.
535 void viewCFGOnly() const;
537 /// Methods for support type inquiry through isa, cast, and dyn_cast:
538 static inline bool classof(const Value *V) {
539 return V->getValueID() == Value::FunctionVal;
542 /// dropAllReferences() - This method causes all the subinstructions to "let
543 /// go" of all references that they are maintaining. This allows one to
544 /// 'delete' a whole module at a time, even though there may be circular
545 /// references... first all references are dropped, and all use counts go to
546 /// zero. Then everything is deleted for real. Note that no operations are
547 /// valid on an object that has "dropped all references", except operator
550 /// Since no other object in the module can have references into the body of a
551 /// function, dropping all references deletes the entire body of the function,
552 /// including any contained basic blocks.
554 void dropAllReferences();
556 /// hasAddressTaken - returns true if there are any uses of this function
557 /// other than direct calls or invokes to it, or blockaddress expressions.
558 /// Optionally passes back an offending user for diagnostic purposes.
560 bool hasAddressTaken(const User** = nullptr) const;
562 /// isDefTriviallyDead - Return true if it is trivially safe to remove
563 /// this function definition from the module (because it isn't externally
564 /// visible, does not have its address taken, and has no callers). To make
565 /// this more accurate, call removeDeadConstantUsers first.
566 bool isDefTriviallyDead() const;
568 /// callsFunctionThatReturnsTwice - Return true if the function has a call to
569 /// setjmp or other function that gcc recognizes as "returning twice".
570 bool callsFunctionThatReturnsTwice() const;
572 /// \brief Check if this has any metadata.
573 bool hasMetadata() const { return hasMetadataHashEntry(); }
575 /// \brief Get the current metadata attachment, if any.
577 /// Returns \c nullptr if such an attachment is missing.
579 MDNode *getMetadata(unsigned KindID) const;
580 MDNode *getMetadata(StringRef Kind) const;
583 /// \brief Set a particular kind of metadata attachment.
585 /// Sets the given attachment to \c MD, erasing it if \c MD is \c nullptr or
586 /// replacing it if it already exists.
588 void setMetadata(unsigned KindID, MDNode *MD);
589 void setMetadata(StringRef Kind, MDNode *MD);
592 /// \brief Get all current metadata attachments.
594 getAllMetadata(SmallVectorImpl<std::pair<unsigned, MDNode *>> &MDs) const;
596 /// \brief Drop metadata not in the given list.
598 /// Drop all metadata from \c this not included in \c KnownIDs.
599 void dropUnknownMetadata(ArrayRef<unsigned> KnownIDs);
601 /// \brief Set the attached subprogram.
603 /// Calls \a setMetadata() with \a LLVMContext::MD_dbg.
604 void setSubprogram(DISubprogram *SP);
606 /// \brief Get the attached subprogram.
608 /// Calls \a getMetadata() with \a LLVMContext::MD_dbg and casts the result
609 /// to \a DISubprogram.
610 DISubprogram *getSubprogram() const;
613 // Shadow Value::setValueSubclassData with a private forwarding method so that
614 // subclasses cannot accidentally use it.
615 void setValueSubclassData(unsigned short D) {
616 Value::setValueSubclassData(D);
619 bool hasMetadataHashEntry() const {
620 return getGlobalObjectSubClassData() & HasMetadataHashEntryBit;
622 void setHasMetadataHashEntry(bool HasEntry) {
623 setGlobalObjectBit(HasMetadataHashEntryBit, HasEntry);
626 void clearMetadata();
629 inline ValueSymbolTable *
630 ilist_traits<BasicBlock>::getSymTab(Function *F) {
631 return F ? &F->getValueSymbolTable() : nullptr;
634 inline ValueSymbolTable *
635 ilist_traits<Argument>::getSymTab(Function *F) {
636 return F ? &F->getValueSymbolTable() : nullptr;
640 struct OperandTraits<Function> : public OptionalOperandTraits<Function> {};
642 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(Function, Value)
644 } // End llvm namespace