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/Support/Compiler.h"
35 template<> struct ilist_traits<Argument>
36 : public SymbolTableListTraits<Argument, Function> {
38 Argument *createSentinel() const {
39 return static_cast<Argument*>(&Sentinel);
41 static void destroySentinel(Argument*) {}
43 Argument *provideInitialHead() const { return createSentinel(); }
44 Argument *ensureHead(Argument*) const { return createSentinel(); }
45 static void noteHead(Argument*, Argument*) {}
47 static ValueSymbolTable *getSymTab(Function *ItemParent);
49 mutable ilist_half_node<Argument> Sentinel;
52 class Function : public GlobalObject, public ilist_node<Function> {
54 typedef iplist<Argument> ArgumentListType;
55 typedef iplist<BasicBlock> BasicBlockListType;
57 // BasicBlock iterators...
58 typedef BasicBlockListType::iterator iterator;
59 typedef BasicBlockListType::const_iterator const_iterator;
61 typedef ArgumentListType::iterator arg_iterator;
62 typedef ArgumentListType::const_iterator const_arg_iterator;
65 // Important things that make up a function!
66 BasicBlockListType BasicBlocks; ///< The basic blocks
67 mutable ArgumentListType ArgumentList; ///< The formal arguments
68 ValueSymbolTable *SymTab; ///< Symbol table of args/instructions
69 AttributeSet AttributeSets; ///< Parameter attributes
75 * bit 0 : HasLazyArguments
76 * bit 1 : HasPrefixData
77 * bit 2 : HasPrologueData
78 * bit 3-6: CallingConvention
81 /// Bits from GlobalObject::GlobalObjectSubclassData.
83 /// Whether this function is materializable.
84 IsMaterializableBit = 1 << 0,
85 HasMetadataHashEntryBit = 1 << 1
87 void setGlobalObjectBit(unsigned Mask, bool Value) {
88 setGlobalObjectSubClassData((~Mask & getGlobalObjectSubClassData()) |
92 friend class SymbolTableListTraits<Function, Module>;
94 void setParent(Module *parent);
96 /// hasLazyArguments/CheckLazyArguments - The argument list of a function is
97 /// built on demand, so that the list isn't allocated until the first client
98 /// needs it. The hasLazyArguments predicate returns true if the arg list
99 /// hasn't been set up yet.
100 bool hasLazyArguments() const {
101 return getSubclassDataFromValue() & (1<<0);
103 void CheckLazyArguments() const {
104 if (hasLazyArguments())
105 BuildLazyArguments();
107 void BuildLazyArguments() const;
109 Function(const Function&) = delete;
110 void operator=(const Function&) = delete;
112 /// Function ctor - If the (optional) Module argument is specified, the
113 /// function is automatically inserted into the end of the function list for
116 Function(FunctionType *Ty, LinkageTypes Linkage,
117 const Twine &N = "", Module *M = nullptr);
120 static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
121 const Twine &N = "", Module *M = nullptr) {
122 return new(0) Function(Ty, Linkage, N, M);
125 ~Function() override;
127 Type *getReturnType() const; // Return the type of the ret val
128 FunctionType *getFunctionType() const; // Return the FunctionType for me
130 /// getContext - Return a reference to the LLVMContext associated with this
132 LLVMContext &getContext() const;
134 /// isVarArg - Return true if this function takes a variable number of
136 bool isVarArg() const;
138 bool isMaterializable() const;
139 void setIsMaterializable(bool V);
141 /// getIntrinsicID - This method returns the ID number of the specified
142 /// function, or Intrinsic::not_intrinsic if the function is not an
143 /// intrinsic, or if the pointer is null. This value is always defined to be
144 /// zero to allow easy checking for whether a function is intrinsic or not.
145 /// The particular intrinsic functions which correspond to this value are
146 /// defined in llvm/Intrinsics.h.
147 Intrinsic::ID getIntrinsicID() const LLVM_READONLY { return IntID; }
148 bool isIntrinsic() const { return getName().startswith("llvm."); }
150 /// \brief Recalculate the ID for this function if it is an Intrinsic defined
151 /// in llvm/Intrinsics.h. Sets the intrinsic ID to Intrinsic::not_intrinsic
152 /// if the name of this function does not match an intrinsic in that header.
153 /// Note, this method does not need to be called directly, as it is called
154 /// from Value::setName() whenever the name of this function changes.
155 void recalculateIntrinsicID();
157 /// getCallingConv()/setCallingConv(CC) - These method get and set the
158 /// calling convention of this function. The enum values for the known
159 /// calling conventions are defined in CallingConv.h.
160 CallingConv::ID getCallingConv() const {
161 return static_cast<CallingConv::ID>(getSubclassDataFromValue() >> 3);
163 void setCallingConv(CallingConv::ID CC) {
164 setValueSubclassData((getSubclassDataFromValue() & 7) |
165 (static_cast<unsigned>(CC) << 3));
168 /// @brief Return the attribute list for this Function.
169 AttributeSet getAttributes() const { return AttributeSets; }
171 /// @brief Set the attribute list for this Function.
172 void setAttributes(AttributeSet attrs) { AttributeSets = attrs; }
174 /// @brief Add function attributes to this function.
175 void addFnAttr(Attribute::AttrKind N) {
176 setAttributes(AttributeSets.addAttribute(getContext(),
177 AttributeSet::FunctionIndex, N));
180 /// @brief Remove function attributes from this function.
181 void removeFnAttr(Attribute::AttrKind N) {
182 setAttributes(AttributeSets.removeAttribute(
183 getContext(), AttributeSet::FunctionIndex, N));
186 /// @brief Add function attributes to this function.
187 void addFnAttr(StringRef Kind) {
189 AttributeSets.addAttribute(getContext(),
190 AttributeSet::FunctionIndex, Kind));
192 void addFnAttr(StringRef Kind, StringRef Value) {
194 AttributeSets.addAttribute(getContext(),
195 AttributeSet::FunctionIndex, Kind, Value));
198 /// Set the entry count for this function.
199 void setEntryCount(uint64_t Count);
201 /// Get the entry count for this function.
202 Optional<uint64_t> getEntryCount() const;
204 /// @brief Return true if the function has the attribute.
205 bool hasFnAttribute(Attribute::AttrKind Kind) const {
206 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
208 bool hasFnAttribute(StringRef Kind) const {
209 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
212 /// @brief Return the attribute for the given attribute kind.
213 Attribute getFnAttribute(Attribute::AttrKind Kind) const {
214 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
216 Attribute getFnAttribute(StringRef Kind) const {
217 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
220 /// \brief Return the stack alignment for the function.
221 unsigned getFnStackAlignment() const {
222 return AttributeSets.getStackAlignment(AttributeSet::FunctionIndex);
225 /// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
226 /// to use during code generation.
228 const char *getGC() const;
229 void setGC(const char *Str);
232 /// @brief adds the attribute to the list of attributes.
233 void addAttribute(unsigned i, Attribute::AttrKind attr);
235 /// @brief adds the attributes to the list of attributes.
236 void addAttributes(unsigned i, AttributeSet attrs);
238 /// @brief removes the attributes from the list of attributes.
239 void removeAttributes(unsigned i, AttributeSet attr);
241 /// @brief adds the dereferenceable attribute to the list of attributes.
242 void addDereferenceableAttr(unsigned i, uint64_t Bytes);
244 /// @brief adds the dereferenceable_or_null attribute to the list of
246 void addDereferenceableOrNullAttr(unsigned i, uint64_t Bytes);
248 /// @brief Extract the alignment for a call or parameter (0=unknown).
249 unsigned getParamAlignment(unsigned i) const {
250 return AttributeSets.getParamAlignment(i);
253 /// @brief Extract the number of dereferenceable bytes for a call or
254 /// parameter (0=unknown).
255 uint64_t getDereferenceableBytes(unsigned i) const {
256 return AttributeSets.getDereferenceableBytes(i);
259 /// @brief Extract the number of dereferenceable_or_null bytes for a call or
260 /// parameter (0=unknown).
261 uint64_t getDereferenceableOrNullBytes(unsigned i) const {
262 return AttributeSets.getDereferenceableOrNullBytes(i);
265 /// @brief Determine if the function does not access memory.
266 bool doesNotAccessMemory() const {
267 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
268 Attribute::ReadNone);
270 void setDoesNotAccessMemory() {
271 addFnAttr(Attribute::ReadNone);
274 /// @brief Determine if the function does not access or only reads memory.
275 bool onlyReadsMemory() const {
276 return doesNotAccessMemory() ||
277 AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
278 Attribute::ReadOnly);
280 void setOnlyReadsMemory() {
281 addFnAttr(Attribute::ReadOnly);
284 /// @brief Determine if the function cannot return.
285 bool doesNotReturn() const {
286 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
287 Attribute::NoReturn);
289 void setDoesNotReturn() {
290 addFnAttr(Attribute::NoReturn);
293 /// @brief Determine if the function cannot unwind.
294 bool doesNotThrow() const {
295 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
296 Attribute::NoUnwind);
298 void setDoesNotThrow() {
299 addFnAttr(Attribute::NoUnwind);
302 /// @brief Determine if the call cannot be duplicated.
303 bool cannotDuplicate() const {
304 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
305 Attribute::NoDuplicate);
307 void setCannotDuplicate() {
308 addFnAttr(Attribute::NoDuplicate);
311 /// @brief Determine if the call is convergent.
312 bool isConvergent() const {
313 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
314 Attribute::Convergent);
316 void setConvergent() {
317 addFnAttr(Attribute::Convergent);
321 /// @brief True if the ABI mandates (or the user requested) that this
322 /// function be in a unwind table.
323 bool hasUWTable() const {
324 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
327 void setHasUWTable() {
328 addFnAttr(Attribute::UWTable);
331 /// @brief True if this function needs an unwind table.
332 bool needsUnwindTableEntry() const {
333 return hasUWTable() || !doesNotThrow();
336 /// @brief Determine if the function returns a structure through first
337 /// pointer argument.
338 bool hasStructRetAttr() const {
339 return AttributeSets.hasAttribute(1, Attribute::StructRet) ||
340 AttributeSets.hasAttribute(2, Attribute::StructRet);
343 /// @brief Determine if the parameter does not alias other parameters.
344 /// @param n The parameter to check. 1 is the first parameter, 0 is the return
345 bool doesNotAlias(unsigned n) const {
346 return AttributeSets.hasAttribute(n, Attribute::NoAlias);
348 void setDoesNotAlias(unsigned n) {
349 addAttribute(n, Attribute::NoAlias);
352 /// @brief Determine if the parameter can be captured.
353 /// @param n The parameter to check. 1 is the first parameter, 0 is the return
354 bool doesNotCapture(unsigned n) const {
355 return AttributeSets.hasAttribute(n, Attribute::NoCapture);
357 void setDoesNotCapture(unsigned n) {
358 addAttribute(n, Attribute::NoCapture);
361 bool doesNotAccessMemory(unsigned n) const {
362 return AttributeSets.hasAttribute(n, Attribute::ReadNone);
364 void setDoesNotAccessMemory(unsigned n) {
365 addAttribute(n, Attribute::ReadNone);
368 bool onlyReadsMemory(unsigned n) const {
369 return doesNotAccessMemory(n) ||
370 AttributeSets.hasAttribute(n, Attribute::ReadOnly);
372 void setOnlyReadsMemory(unsigned n) {
373 addAttribute(n, Attribute::ReadOnly);
376 /// copyAttributesFrom - copy all additional attributes (those not needed to
377 /// create a Function) from the Function Src to this one.
378 void copyAttributesFrom(const GlobalValue *Src) override;
380 /// deleteBody - This method deletes the body of the function, and converts
381 /// the linkage to external.
385 setLinkage(ExternalLinkage);
388 /// removeFromParent - This method unlinks 'this' from the containing module,
389 /// but does not delete it.
391 void removeFromParent() override;
393 /// eraseFromParent - This method unlinks 'this' from the containing module
396 void eraseFromParent() override;
399 /// Get the underlying elements of the Function... the basic block list is
400 /// empty for external functions.
402 const ArgumentListType &getArgumentList() const {
403 CheckLazyArguments();
406 ArgumentListType &getArgumentList() {
407 CheckLazyArguments();
410 static iplist<Argument> Function::*getSublistAccess(Argument*) {
411 return &Function::ArgumentList;
414 const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
415 BasicBlockListType &getBasicBlockList() { return BasicBlocks; }
416 static iplist<BasicBlock> Function::*getSublistAccess(BasicBlock*) {
417 return &Function::BasicBlocks;
420 const BasicBlock &getEntryBlock() const { return front(); }
421 BasicBlock &getEntryBlock() { return front(); }
423 //===--------------------------------------------------------------------===//
424 // Symbol Table Accessing functions...
426 /// getSymbolTable() - Return the symbol table...
428 inline ValueSymbolTable &getValueSymbolTable() { return *SymTab; }
429 inline const ValueSymbolTable &getValueSymbolTable() const { return *SymTab; }
432 //===--------------------------------------------------------------------===//
433 // BasicBlock iterator forwarding functions
435 iterator begin() { return BasicBlocks.begin(); }
436 const_iterator begin() const { return BasicBlocks.begin(); }
437 iterator end () { return BasicBlocks.end(); }
438 const_iterator end () const { return BasicBlocks.end(); }
440 size_t size() const { return BasicBlocks.size(); }
441 bool empty() const { return BasicBlocks.empty(); }
442 const BasicBlock &front() const { return BasicBlocks.front(); }
443 BasicBlock &front() { return BasicBlocks.front(); }
444 const BasicBlock &back() const { return BasicBlocks.back(); }
445 BasicBlock &back() { return BasicBlocks.back(); }
447 /// @name Function Argument Iteration
450 arg_iterator arg_begin() {
451 CheckLazyArguments();
452 return ArgumentList.begin();
454 const_arg_iterator arg_begin() const {
455 CheckLazyArguments();
456 return ArgumentList.begin();
458 arg_iterator arg_end() {
459 CheckLazyArguments();
460 return ArgumentList.end();
462 const_arg_iterator arg_end() const {
463 CheckLazyArguments();
464 return ArgumentList.end();
467 iterator_range<arg_iterator> args() {
468 return iterator_range<arg_iterator>(arg_begin(), arg_end());
471 iterator_range<const_arg_iterator> args() const {
472 return iterator_range<const_arg_iterator>(arg_begin(), arg_end());
477 size_t arg_size() const;
478 bool arg_empty() const;
480 bool hasPrefixData() const {
481 return getSubclassDataFromValue() & (1<<1);
484 Constant *getPrefixData() const;
485 void setPrefixData(Constant *PrefixData);
487 bool hasPrologueData() const {
488 return getSubclassDataFromValue() & (1<<2);
491 Constant *getPrologueData() const;
492 void setPrologueData(Constant *PrologueData);
494 /// Print the function to an output stream with an optional
495 /// AssemblyAnnotationWriter.
496 void print(raw_ostream &OS, AssemblyAnnotationWriter *AAW = nullptr) const;
498 /// viewCFG - This function is meant for use from the debugger. You can just
499 /// say 'call F->viewCFG()' and a ghostview window should pop up from the
500 /// program, displaying the CFG of the current function with the code for each
501 /// basic block inside. This depends on there being a 'dot' and 'gv' program
504 void viewCFG() const;
506 /// viewCFGOnly - This function is meant for use from the debugger. It works
507 /// just like viewCFG, but it does not include the contents of basic blocks
508 /// into the nodes, just the label. If you are only interested in the CFG
509 /// this can make the graph smaller.
511 void viewCFGOnly() const;
513 /// Methods for support type inquiry through isa, cast, and dyn_cast:
514 static inline bool classof(const Value *V) {
515 return V->getValueID() == Value::FunctionVal;
518 /// dropAllReferences() - This method causes all the subinstructions to "let
519 /// go" of all references that they are maintaining. This allows one to
520 /// 'delete' a whole module at a time, even though there may be circular
521 /// references... first all references are dropped, and all use counts go to
522 /// zero. Then everything is deleted for real. Note that no operations are
523 /// valid on an object that has "dropped all references", except operator
526 /// Since no other object in the module can have references into the body of a
527 /// function, dropping all references deletes the entire body of the function,
528 /// including any contained basic blocks.
530 void dropAllReferences();
532 /// hasAddressTaken - returns true if there are any uses of this function
533 /// other than direct calls or invokes to it, or blockaddress expressions.
534 /// Optionally passes back an offending user for diagnostic purposes.
536 bool hasAddressTaken(const User** = nullptr) const;
538 /// isDefTriviallyDead - Return true if it is trivially safe to remove
539 /// this function definition from the module (because it isn't externally
540 /// visible, does not have its address taken, and has no callers). To make
541 /// this more accurate, call removeDeadConstantUsers first.
542 bool isDefTriviallyDead() const;
544 /// callsFunctionThatReturnsTwice - Return true if the function has a call to
545 /// setjmp or other function that gcc recognizes as "returning twice".
546 bool callsFunctionThatReturnsTwice() const;
548 /// \brief Check if this has any metadata.
549 bool hasMetadata() const { return hasMetadataHashEntry(); }
551 /// \brief Get the current metadata attachment, if any.
553 /// Returns \c nullptr if such an attachment is missing.
555 MDNode *getMetadata(unsigned KindID) const;
556 MDNode *getMetadata(StringRef Kind) const;
559 /// \brief Set a particular kind of metadata attachment.
561 /// Sets the given attachment to \c MD, erasing it if \c MD is \c nullptr or
562 /// replacing it if it already exists.
564 void setMetadata(unsigned KindID, MDNode *MD);
565 void setMetadata(StringRef Kind, MDNode *MD);
568 /// \brief Get all current metadata attachments.
570 getAllMetadata(SmallVectorImpl<std::pair<unsigned, MDNode *>> &MDs) const;
572 /// \brief Drop metadata not in the given list.
574 /// Drop all metadata from \c this not included in \c KnownIDs.
575 void dropUnknownMetadata(ArrayRef<unsigned> KnownIDs);
578 // Shadow Value::setValueSubclassData with a private forwarding method so that
579 // subclasses cannot accidentally use it.
580 void setValueSubclassData(unsigned short D) {
581 Value::setValueSubclassData(D);
584 bool hasMetadataHashEntry() const {
585 return getGlobalObjectSubClassData() & HasMetadataHashEntryBit;
587 void setHasMetadataHashEntry(bool HasEntry) {
588 setGlobalObjectBit(HasMetadataHashEntryBit, HasEntry);
591 void clearMetadata();
594 inline ValueSymbolTable *
595 ilist_traits<BasicBlock>::getSymTab(Function *F) {
596 return F ? &F->getValueSymbolTable() : nullptr;
599 inline ValueSymbolTable *
600 ilist_traits<Argument>::getSymTab(Function *F) {
601 return F ? &F->getValueSymbolTable() : nullptr;
604 } // End llvm namespace