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"
38 struct SymbolTableListSentinelTraits<Argument>
39 : public ilist_half_embedded_sentinel_traits<Argument> {};
41 class Function : public GlobalObject, public ilist_node<Function> {
43 typedef SymbolTableList<Argument> ArgumentListType;
44 typedef SymbolTableList<BasicBlock> BasicBlockListType;
46 // BasicBlock iterators...
47 typedef BasicBlockListType::iterator iterator;
48 typedef BasicBlockListType::const_iterator const_iterator;
50 typedef ArgumentListType::iterator arg_iterator;
51 typedef ArgumentListType::const_iterator const_arg_iterator;
54 // Important things that make up a function!
55 BasicBlockListType BasicBlocks; ///< The basic blocks
56 mutable ArgumentListType ArgumentList; ///< The formal arguments
57 ValueSymbolTable *SymTab; ///< Symbol table of args/instructions
58 AttributeSet AttributeSets; ///< Parameter attributes
64 * bit 0 : HasLazyArguments
65 * bit 1 : HasPrefixData
66 * bit 2 : HasPrologueData
68 * bits 4-13 : CallingConvention
69 * bits 14-15 : [reserved]
72 /// Bits from GlobalObject::GlobalObjectSubclassData.
74 /// Whether this function is materializable.
75 IsMaterializableBit = 1 << 0,
76 HasMetadataHashEntryBit = 1 << 1
78 void setGlobalObjectBit(unsigned Mask, bool Value) {
79 setGlobalObjectSubClassData((~Mask & getGlobalObjectSubClassData()) |
83 friend class SymbolTableListTraits<Function>;
85 void setParent(Module *parent);
87 /// hasLazyArguments/CheckLazyArguments - The argument list of a function is
88 /// built on demand, so that the list isn't allocated until the first client
89 /// needs it. The hasLazyArguments predicate returns true if the arg list
90 /// hasn't been set up yet.
91 bool hasLazyArguments() const {
92 return getSubclassDataFromValue() & (1<<0);
94 void CheckLazyArguments() const {
95 if (hasLazyArguments())
98 void BuildLazyArguments() const;
100 Function(const Function&) = delete;
101 void operator=(const Function&) = delete;
103 /// Function ctor - If the (optional) Module argument is specified, the
104 /// function is automatically inserted into the end of the function list for
107 Function(FunctionType *Ty, LinkageTypes Linkage,
108 const Twine &N = "", Module *M = nullptr);
111 static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
112 const Twine &N = "", Module *M = nullptr) {
113 return new(1) Function(Ty, Linkage, N, M);
116 ~Function() override;
118 /// \brief Provide fast operand accessors
119 DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
121 /// \brief Get the personality function associated with this function.
122 bool hasPersonalityFn() const { return getNumOperands() != 0; }
123 Constant *getPersonalityFn() const {
124 assert(hasPersonalityFn());
125 return cast<Constant>(Op<0>());
127 void setPersonalityFn(Constant *C);
129 Type *getReturnType() const; // Return the type of the ret val
130 FunctionType *getFunctionType() const; // Return the FunctionType for me
132 /// getContext - Return a reference to the LLVMContext associated with this
134 LLVMContext &getContext() const;
136 /// isVarArg - Return true if this function takes a variable number of
138 bool isVarArg() const;
140 bool isMaterializable() const;
141 void setIsMaterializable(bool V);
143 /// getIntrinsicID - This method returns the ID number of the specified
144 /// function, or Intrinsic::not_intrinsic if the function is not an
145 /// intrinsic, or if the pointer is null. This value is always defined to be
146 /// zero to allow easy checking for whether a function is intrinsic or not.
147 /// The particular intrinsic functions which correspond to this value are
148 /// defined in llvm/Intrinsics.h.
149 Intrinsic::ID getIntrinsicID() const LLVM_READONLY { return IntID; }
150 bool isIntrinsic() const { return getName().startswith("llvm."); }
152 /// \brief Recalculate the ID for this function if it is an Intrinsic defined
153 /// in llvm/Intrinsics.h. Sets the intrinsic ID to Intrinsic::not_intrinsic
154 /// if the name of this function does not match an intrinsic in that header.
155 /// Note, this method does not need to be called directly, as it is called
156 /// from Value::setName() whenever the name of this function changes.
157 void recalculateIntrinsicID();
159 /// getCallingConv()/setCallingConv(CC) - These method get and set the
160 /// calling convention of this function. The enum values for the known
161 /// calling conventions are defined in CallingConv.h.
162 CallingConv::ID getCallingConv() const {
163 return static_cast<CallingConv::ID>((getSubclassDataFromValue() >> 4) &
166 void setCallingConv(CallingConv::ID CC) {
167 auto ID = static_cast<unsigned>(CC);
168 assert(!(ID & ~CallingConv::MaxID) && "Unsupported calling convention");
169 setValueSubclassData((getSubclassDataFromValue() & 0xc00f) | (ID << 4));
172 /// @brief Return the attribute list for this Function.
173 AttributeSet getAttributes() const { return AttributeSets; }
175 /// @brief Set the attribute list for this Function.
176 void setAttributes(AttributeSet attrs) { AttributeSets = attrs; }
178 /// @brief Add function attributes to this function.
179 void addFnAttr(Attribute::AttrKind N) {
180 setAttributes(AttributeSets.addAttribute(getContext(),
181 AttributeSet::FunctionIndex, N));
184 /// @brief Remove function attributes from this function.
185 void removeFnAttr(Attribute::AttrKind N) {
186 setAttributes(AttributeSets.removeAttribute(
187 getContext(), AttributeSet::FunctionIndex, N));
190 /// @brief Add function attributes to this function.
191 void addFnAttr(StringRef Kind) {
193 AttributeSets.addAttribute(getContext(),
194 AttributeSet::FunctionIndex, Kind));
196 void addFnAttr(StringRef Kind, StringRef Value) {
198 AttributeSets.addAttribute(getContext(),
199 AttributeSet::FunctionIndex, Kind, Value));
202 /// Set the entry count for this function.
203 void setEntryCount(uint64_t Count);
205 /// Get the entry count for this function.
206 Optional<uint64_t> getEntryCount() const;
208 /// @brief Return true if the function has the attribute.
209 bool hasFnAttribute(Attribute::AttrKind Kind) const {
210 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
212 bool hasFnAttribute(StringRef Kind) const {
213 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex, Kind);
216 /// @brief Return the attribute for the given attribute kind.
217 Attribute getFnAttribute(Attribute::AttrKind Kind) const {
218 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
220 Attribute getFnAttribute(StringRef Kind) const {
221 return AttributeSets.getAttribute(AttributeSet::FunctionIndex, Kind);
224 /// \brief Return the stack alignment for the function.
225 unsigned getFnStackAlignment() const {
226 return AttributeSets.getStackAlignment(AttributeSet::FunctionIndex);
229 /// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
230 /// to use during code generation.
232 const char *getGC() const;
233 void setGC(const char *Str);
236 /// @brief adds the attribute to the list of attributes.
237 void addAttribute(unsigned i, Attribute::AttrKind attr);
239 /// @brief adds the attributes to the list of attributes.
240 void addAttributes(unsigned i, AttributeSet attrs);
242 /// @brief removes the attributes from the list of attributes.
243 void removeAttributes(unsigned i, AttributeSet attr);
245 /// @brief adds the dereferenceable attribute to the list of attributes.
246 void addDereferenceableAttr(unsigned i, uint64_t Bytes);
248 /// @brief adds the dereferenceable_or_null attribute to the list of
250 void addDereferenceableOrNullAttr(unsigned i, uint64_t Bytes);
252 /// @brief Extract the alignment for a call or parameter (0=unknown).
253 unsigned getParamAlignment(unsigned i) const {
254 return AttributeSets.getParamAlignment(i);
257 /// @brief Extract the number of dereferenceable bytes for a call or
258 /// parameter (0=unknown).
259 uint64_t getDereferenceableBytes(unsigned i) const {
260 return AttributeSets.getDereferenceableBytes(i);
263 /// @brief Extract the number of dereferenceable_or_null bytes for a call or
264 /// parameter (0=unknown).
265 uint64_t getDereferenceableOrNullBytes(unsigned i) const {
266 return AttributeSets.getDereferenceableOrNullBytes(i);
269 /// @brief Determine if the function does not access memory.
270 bool doesNotAccessMemory() const {
271 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
272 Attribute::ReadNone);
274 void setDoesNotAccessMemory() {
275 addFnAttr(Attribute::ReadNone);
278 /// @brief Determine if the function does not access or only reads memory.
279 bool onlyReadsMemory() const {
280 return doesNotAccessMemory() ||
281 AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
282 Attribute::ReadOnly);
284 void setOnlyReadsMemory() {
285 addFnAttr(Attribute::ReadOnly);
288 /// @brief Determine if the call can access memmory only using pointers based
289 /// on its arguments.
290 bool onlyAccessesArgMemory() const {
291 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
292 Attribute::ArgMemOnly);
294 void setOnlyAccessesArgMemory() { addFnAttr(Attribute::ArgMemOnly); }
296 /// @brief Determine if the function cannot return.
297 bool doesNotReturn() const {
298 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
299 Attribute::NoReturn);
301 void setDoesNotReturn() {
302 addFnAttr(Attribute::NoReturn);
305 /// @brief Determine if the function cannot unwind.
306 bool doesNotThrow() const {
307 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
308 Attribute::NoUnwind);
310 void setDoesNotThrow() {
311 addFnAttr(Attribute::NoUnwind);
314 /// @brief Determine if the call cannot be duplicated.
315 bool cannotDuplicate() const {
316 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
317 Attribute::NoDuplicate);
319 void setCannotDuplicate() {
320 addFnAttr(Attribute::NoDuplicate);
323 /// @brief Determine if the call is convergent.
324 bool isConvergent() const {
325 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
326 Attribute::Convergent);
328 void setConvergent() {
329 addFnAttr(Attribute::Convergent);
332 /// Determine if the function is known not to recurse, directly or
334 bool doesNotRecurse() const {
335 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
336 Attribute::NoRecurse);
338 void setDoesNotRecurse() {
339 addFnAttr(Attribute::NoRecurse);
342 /// @brief True if the ABI mandates (or the user requested) that this
343 /// function be in a unwind table.
344 bool hasUWTable() const {
345 return AttributeSets.hasAttribute(AttributeSet::FunctionIndex,
348 void setHasUWTable() {
349 addFnAttr(Attribute::UWTable);
352 /// @brief True if this function needs an unwind table.
353 bool needsUnwindTableEntry() const {
354 return hasUWTable() || !doesNotThrow();
357 /// @brief Determine if the function returns a structure through first
358 /// pointer argument.
359 bool hasStructRetAttr() const {
360 return AttributeSets.hasAttribute(1, Attribute::StructRet) ||
361 AttributeSets.hasAttribute(2, Attribute::StructRet);
364 /// @brief Determine if the parameter or return value is marked with NoAlias
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 ArgumentListType Function::*getSublistAccess(Argument*) {
440 return &Function::ArgumentList;
443 const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
444 BasicBlockListType &getBasicBlockList() { return BasicBlocks; }
445 static BasicBlockListType 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();
630 struct OperandTraits<Function> : public OptionalOperandTraits<Function> {};
632 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(Function, Value)
634 } // End llvm namespace