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1 //===- llvm/Function.h - Class to represent a single function ---*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file contains the declaration of the Function class, which represents a
11 // single function/procedure in LLVM.
12 //
13 // A function basically consists of a list of basic blocks, a list of arguments,
14 // and a symbol table.
15 //
16 //===----------------------------------------------------------------------===//
17 
18 #ifndef LLVM_IR_FUNCTION_H
19 #define LLVM_IR_FUNCTION_H
20 
21 #include "llvm/ADT/DenseSet.h"
22 #include "llvm/ADT/StringRef.h"
23 #include "llvm/ADT/Twine.h"
24 #include "llvm/ADT/ilist_node.h"
25 #include "llvm/ADT/iterator_range.h"
26 #include "llvm/IR/Argument.h"
27 #include "llvm/IR/Attributes.h"
28 #include "llvm/IR/BasicBlock.h"
29 #include "llvm/IR/CallingConv.h"
30 #include "llvm/IR/DerivedTypes.h"
31 #include "llvm/IR/GlobalObject.h"
32 #include "llvm/IR/GlobalValue.h"
33 #include "llvm/IR/OperandTraits.h"
34 #include "llvm/IR/SymbolTableListTraits.h"
35 #include "llvm/IR/Value.h"
36 #include "llvm/Support/Casting.h"
37 #include "llvm/Support/Compiler.h"
38 #include <cassert>
39 #include <cstddef>
40 #include <cstdint>
41 #include <memory>
42 #include <string>
43 
44 namespace llvm {
45 
46 namespace Intrinsic {
47 enum ID : unsigned;
48 }
49 
50 class AssemblyAnnotationWriter;
51 class Constant;
52 class DISubprogram;
53 class LLVMContext;
54 class Module;
55 template <typename T> class Optional;
56 class raw_ostream;
57 class Type;
58 class User;
59 
60 class Function : public GlobalObject, public ilist_node<Function> {
61 public:
62   using BasicBlockListType = SymbolTableList<BasicBlock>;
63 
64   // BasicBlock iterators...
65   using iterator = BasicBlockListType::iterator;
66   using const_iterator = BasicBlockListType::const_iterator;
67 
68   using arg_iterator = Argument *;
69   using const_arg_iterator = const Argument *;
70 
71 private:
72   // Important things that make up a function!
73   BasicBlockListType BasicBlocks;         ///< The basic blocks
74   mutable Argument *Arguments = nullptr;  ///< The formal arguments
75   size_t NumArgs;
76   std::unique_ptr<ValueSymbolTable>
77       SymTab;                             ///< Symbol table of args/instructions
78   AttributeList AttributeSets;            ///< Parameter attributes
79 
80   /*
81    * Value::SubclassData
82    *
83    * bit 0      : HasLazyArguments
84    * bit 1      : HasPrefixData
85    * bit 2      : HasPrologueData
86    * bit 3      : HasPersonalityFn
87    * bits 4-13  : CallingConvention
88    * bits 14    : HasGC
89    * bits 15 : [reserved]
90    */
91 
92   /// Bits from GlobalObject::GlobalObjectSubclassData.
93   enum {
94     /// Whether this function is materializable.
95     IsMaterializableBit = 0,
96   };
97 
98   friend class SymbolTableListTraits<Function>;
99 
100   /// hasLazyArguments/CheckLazyArguments - The argument list of a function is
101   /// built on demand, so that the list isn't allocated until the first client
102   /// needs it.  The hasLazyArguments predicate returns true if the arg list
103   /// hasn't been set up yet.
104 public:
hasLazyArguments()105   bool hasLazyArguments() const {
106     return getSubclassDataFromValue() & (1<<0);
107   }
108 
109 private:
CheckLazyArguments()110   void CheckLazyArguments() const {
111     if (hasLazyArguments())
112       BuildLazyArguments();
113   }
114 
115   void BuildLazyArguments() const;
116 
117   void clearArguments();
118 
119   /// Function ctor - If the (optional) Module argument is specified, the
120   /// function is automatically inserted into the end of the function list for
121   /// the module.
122   ///
123   Function(FunctionType *Ty, LinkageTypes Linkage,
124            const Twine &N = "", Module *M = nullptr);
125 
126 public:
127   Function(const Function&) = delete;
128   void operator=(const Function&) = delete;
129   ~Function();
130 
131   // This is here to help easily convert from FunctionT * (Function * or
132   // MachineFunction *) in BlockFrequencyInfoImpl to Function * by calling
133   // FunctionT->getFunction().
getFunction()134   const Function &getFunction() const { return *this; }
135 
136   static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
137                           const Twine &N = "", Module *M = nullptr) {
138     return new Function(Ty, Linkage, N, M);
139   }
140 
141   // Provide fast operand accessors.
142   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
143 
144   /// Returns the number of non-debug IR instructions in this function.
145   /// This is equivalent to the sum of the sizes of each basic block contained
146   /// within this function.
147   unsigned getInstructionCount();
148 
149   /// Returns the FunctionType for me.
getFunctionType()150   FunctionType *getFunctionType() const {
151     return cast<FunctionType>(getValueType());
152   }
153 
154   /// Returns the type of the ret val.
getReturnType()155   Type *getReturnType() const { return getFunctionType()->getReturnType(); }
156 
157   /// getContext - Return a reference to the LLVMContext associated with this
158   /// function.
159   LLVMContext &getContext() const;
160 
161   /// isVarArg - Return true if this function takes a variable number of
162   /// arguments.
isVarArg()163   bool isVarArg() const { return getFunctionType()->isVarArg(); }
164 
isMaterializable()165   bool isMaterializable() const {
166     return getGlobalObjectSubClassData() & (1 << IsMaterializableBit);
167   }
setIsMaterializable(bool V)168   void setIsMaterializable(bool V) {
169     unsigned Mask = 1 << IsMaterializableBit;
170     setGlobalObjectSubClassData((~Mask & getGlobalObjectSubClassData()) |
171                                 (V ? Mask : 0u));
172   }
173 
174   /// getIntrinsicID - This method returns the ID number of the specified
175   /// function, or Intrinsic::not_intrinsic if the function is not an
176   /// intrinsic, or if the pointer is null.  This value is always defined to be
177   /// zero to allow easy checking for whether a function is intrinsic or not.
178   /// The particular intrinsic functions which correspond to this value are
179   /// defined in llvm/Intrinsics.h.
getIntrinsicID()180   Intrinsic::ID getIntrinsicID() const LLVM_READONLY { return IntID; }
181 
182   /// isIntrinsic - Returns true if the function's name starts with "llvm.".
183   /// It's possible for this function to return true while getIntrinsicID()
184   /// returns Intrinsic::not_intrinsic!
isIntrinsic()185   bool isIntrinsic() const { return HasLLVMReservedName; }
186 
187   static Intrinsic::ID lookupIntrinsicID(StringRef Name);
188 
189   /// Recalculate the ID for this function if it is an Intrinsic defined
190   /// in llvm/Intrinsics.h.  Sets the intrinsic ID to Intrinsic::not_intrinsic
191   /// if the name of this function does not match an intrinsic in that header.
192   /// Note, this method does not need to be called directly, as it is called
193   /// from Value::setName() whenever the name of this function changes.
194   void recalculateIntrinsicID();
195 
196   /// getCallingConv()/setCallingConv(CC) - These method get and set the
197   /// calling convention of this function.  The enum values for the known
198   /// calling conventions are defined in CallingConv.h.
getCallingConv()199   CallingConv::ID getCallingConv() const {
200     return static_cast<CallingConv::ID>((getSubclassDataFromValue() >> 4) &
201                                         CallingConv::MaxID);
202   }
setCallingConv(CallingConv::ID CC)203   void setCallingConv(CallingConv::ID CC) {
204     auto ID = static_cast<unsigned>(CC);
205     assert(!(ID & ~CallingConv::MaxID) && "Unsupported calling convention");
206     setValueSubclassData((getSubclassDataFromValue() & 0xc00f) | (ID << 4));
207   }
208 
209   /// Return the attribute list for this Function.
getAttributes()210   AttributeList getAttributes() const { return AttributeSets; }
211 
212   /// Set the attribute list for this Function.
setAttributes(AttributeList Attrs)213   void setAttributes(AttributeList Attrs) { AttributeSets = Attrs; }
214 
215   /// Add function attributes to this function.
addFnAttr(Attribute::AttrKind Kind)216   void addFnAttr(Attribute::AttrKind Kind) {
217     addAttribute(AttributeList::FunctionIndex, Kind);
218   }
219 
220   /// Add function attributes to this function.
221   void addFnAttr(StringRef Kind, StringRef Val = StringRef()) {
222     addAttribute(AttributeList::FunctionIndex,
223                  Attribute::get(getContext(), Kind, Val));
224   }
225 
226   /// Add function attributes to this function.
addFnAttr(Attribute Attr)227   void addFnAttr(Attribute Attr) {
228     addAttribute(AttributeList::FunctionIndex, Attr);
229   }
230 
231   /// Remove function attributes from this function.
removeFnAttr(Attribute::AttrKind Kind)232   void removeFnAttr(Attribute::AttrKind Kind) {
233     removeAttribute(AttributeList::FunctionIndex, Kind);
234   }
235 
236   /// Remove function attribute from this function.
removeFnAttr(StringRef Kind)237   void removeFnAttr(StringRef Kind) {
238     setAttributes(getAttributes().removeAttribute(
239         getContext(), AttributeList::FunctionIndex, Kind));
240   }
241 
242   enum ProfileCountType { PCT_Invalid, PCT_Real, PCT_Synthetic };
243 
244   /// Class to represent profile counts.
245   ///
246   /// This class represents both real and synthetic profile counts.
247   class ProfileCount {
248   private:
249     uint64_t Count;
250     ProfileCountType PCT;
251     static ProfileCount Invalid;
252 
253   public:
ProfileCount()254     ProfileCount() : Count(-1), PCT(PCT_Invalid) {}
ProfileCount(uint64_t Count,ProfileCountType PCT)255     ProfileCount(uint64_t Count, ProfileCountType PCT)
256         : Count(Count), PCT(PCT) {}
hasValue()257     bool hasValue() const { return PCT != PCT_Invalid; }
getCount()258     uint64_t getCount() const { return Count; }
getType()259     ProfileCountType getType() const { return PCT; }
isSynthetic()260     bool isSynthetic() const { return PCT == PCT_Synthetic; }
261     explicit operator bool() { return hasValue(); }
262     bool operator!() const { return !hasValue(); }
263     // Update the count retaining the same profile count type.
setCount(uint64_t C)264     ProfileCount &setCount(uint64_t C) {
265       Count = C;
266       return *this;
267     }
getInvalid()268     static ProfileCount getInvalid() { return ProfileCount(-1, PCT_Invalid); }
269   };
270 
271   /// Set the entry count for this function.
272   ///
273   /// Entry count is the number of times this function was executed based on
274   /// pgo data. \p Imports points to a set of GUIDs that needs to
275   /// be imported by the function for sample PGO, to enable the same inlines as
276   /// the profiled optimized binary.
277   void setEntryCount(ProfileCount Count,
278                      const DenseSet<GlobalValue::GUID> *Imports = nullptr);
279 
280   /// A convenience wrapper for setting entry count
281   void setEntryCount(uint64_t Count, ProfileCountType Type = PCT_Real,
282                      const DenseSet<GlobalValue::GUID> *Imports = nullptr);
283 
284   /// Get the entry count for this function.
285   ///
286   /// Entry count is the number of times the function was executed based on
287   /// pgo data.
288   ProfileCount getEntryCount() const;
289 
290   /// Return true if the function is annotated with profile data.
291   ///
292   /// Presence of entry counts from a profile run implies the function has
293   /// profile annotations.
hasProfileData()294   bool hasProfileData() const { return getEntryCount().hasValue(); }
295 
296   /// Returns the set of GUIDs that needs to be imported to the function for
297   /// sample PGO, to enable the same inlines as the profiled optimized binary.
298   DenseSet<GlobalValue::GUID> getImportGUIDs() const;
299 
300   /// Set the section prefix for this function.
301   void setSectionPrefix(StringRef Prefix);
302 
303   /// Get the section prefix for this function.
304   Optional<StringRef> getSectionPrefix() const;
305 
306   /// Return true if the function has the attribute.
hasFnAttribute(Attribute::AttrKind Kind)307   bool hasFnAttribute(Attribute::AttrKind Kind) const {
308     return AttributeSets.hasFnAttribute(Kind);
309   }
310 
311   /// Return true if the function has the attribute.
hasFnAttribute(StringRef Kind)312   bool hasFnAttribute(StringRef Kind) const {
313     return AttributeSets.hasFnAttribute(Kind);
314   }
315 
316   /// Return the attribute for the given attribute kind.
getFnAttribute(Attribute::AttrKind Kind)317   Attribute getFnAttribute(Attribute::AttrKind Kind) const {
318     return getAttribute(AttributeList::FunctionIndex, Kind);
319   }
320 
321   /// Return the attribute for the given attribute kind.
getFnAttribute(StringRef Kind)322   Attribute getFnAttribute(StringRef Kind) const {
323     return getAttribute(AttributeList::FunctionIndex, Kind);
324   }
325 
326   /// Return the stack alignment for the function.
getFnStackAlignment()327   unsigned getFnStackAlignment() const {
328     if (!hasFnAttribute(Attribute::StackAlignment))
329       return 0;
330     return AttributeSets.getStackAlignment(AttributeList::FunctionIndex);
331   }
332 
333   /// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
334   ///                             to use during code generation.
hasGC()335   bool hasGC() const {
336     return getSubclassDataFromValue() & (1<<14);
337   }
338   const std::string &getGC() const;
339   void setGC(std::string Str);
340   void clearGC();
341 
342   /// adds the attribute to the list of attributes.
343   void addAttribute(unsigned i, Attribute::AttrKind Kind);
344 
345   /// adds the attribute to the list of attributes.
346   void addAttribute(unsigned i, Attribute Attr);
347 
348   /// adds the attributes to the list of attributes.
349   void addAttributes(unsigned i, const AttrBuilder &Attrs);
350 
351   /// adds the attribute to the list of attributes for the given arg.
352   void addParamAttr(unsigned ArgNo, Attribute::AttrKind Kind);
353 
354   /// adds the attribute to the list of attributes for the given arg.
355   void addParamAttr(unsigned ArgNo, Attribute Attr);
356 
357   /// adds the attributes to the list of attributes for the given arg.
358   void addParamAttrs(unsigned ArgNo, const AttrBuilder &Attrs);
359 
360   /// removes the attribute from the list of attributes.
361   void removeAttribute(unsigned i, Attribute::AttrKind Kind);
362 
363   /// removes the attribute from the list of attributes.
364   void removeAttribute(unsigned i, StringRef Kind);
365 
366   /// removes the attributes from the list of attributes.
367   void removeAttributes(unsigned i, const AttrBuilder &Attrs);
368 
369   /// removes the attribute from the list of attributes.
370   void removeParamAttr(unsigned ArgNo, Attribute::AttrKind Kind);
371 
372   /// removes the attribute from the list of attributes.
373   void removeParamAttr(unsigned ArgNo, StringRef Kind);
374 
375   /// removes the attribute from the list of attributes.
376   void removeParamAttrs(unsigned ArgNo, const AttrBuilder &Attrs);
377 
378   /// check if an attributes is in the list of attributes.
hasAttribute(unsigned i,Attribute::AttrKind Kind)379   bool hasAttribute(unsigned i, Attribute::AttrKind Kind) const {
380     return getAttributes().hasAttribute(i, Kind);
381   }
382 
383   /// check if an attributes is in the list of attributes.
hasParamAttribute(unsigned ArgNo,Attribute::AttrKind Kind)384   bool hasParamAttribute(unsigned ArgNo, Attribute::AttrKind Kind) const {
385     return getAttributes().hasParamAttribute(ArgNo, Kind);
386   }
387 
388   /// gets the attribute from the list of attributes.
getAttribute(unsigned i,Attribute::AttrKind Kind)389   Attribute getAttribute(unsigned i, Attribute::AttrKind Kind) const {
390     return AttributeSets.getAttribute(i, Kind);
391   }
392 
393   /// gets the attribute from the list of attributes.
getAttribute(unsigned i,StringRef Kind)394   Attribute getAttribute(unsigned i, StringRef Kind) const {
395     return AttributeSets.getAttribute(i, Kind);
396   }
397 
398   /// adds the dereferenceable attribute to the list of attributes.
399   void addDereferenceableAttr(unsigned i, uint64_t Bytes);
400 
401   /// adds the dereferenceable attribute to the list of attributes for
402   /// the given arg.
403   void addDereferenceableParamAttr(unsigned ArgNo, uint64_t Bytes);
404 
405   /// adds the dereferenceable_or_null attribute to the list of
406   /// attributes.
407   void addDereferenceableOrNullAttr(unsigned i, uint64_t Bytes);
408 
409   /// adds the dereferenceable_or_null attribute to the list of
410   /// attributes for the given arg.
411   void addDereferenceableOrNullParamAttr(unsigned ArgNo, uint64_t Bytes);
412 
413   /// Extract the alignment for a call or parameter (0=unknown).
getParamAlignment(unsigned ArgNo)414   unsigned getParamAlignment(unsigned ArgNo) const {
415     return AttributeSets.getParamAlignment(ArgNo);
416   }
417 
418   /// Extract the number of dereferenceable bytes for a call or
419   /// parameter (0=unknown).
420   /// @param i AttributeList index, referring to a return value or argument.
getDereferenceableBytes(unsigned i)421   uint64_t getDereferenceableBytes(unsigned i) const {
422     return AttributeSets.getDereferenceableBytes(i);
423   }
424 
425   /// Extract the number of dereferenceable bytes for a parameter.
426   /// @param ArgNo Index of an argument, with 0 being the first function arg.
getParamDereferenceableBytes(unsigned ArgNo)427   uint64_t getParamDereferenceableBytes(unsigned ArgNo) const {
428     return AttributeSets.getParamDereferenceableBytes(ArgNo);
429   }
430 
431   /// Extract the number of dereferenceable_or_null bytes for a call or
432   /// parameter (0=unknown).
433   /// @param i AttributeList index, referring to a return value or argument.
getDereferenceableOrNullBytes(unsigned i)434   uint64_t getDereferenceableOrNullBytes(unsigned i) const {
435     return AttributeSets.getDereferenceableOrNullBytes(i);
436   }
437 
438   /// Extract the number of dereferenceable_or_null bytes for a
439   /// parameter.
440   /// @param ArgNo AttributeList ArgNo, referring to an argument.
getParamDereferenceableOrNullBytes(unsigned ArgNo)441   uint64_t getParamDereferenceableOrNullBytes(unsigned ArgNo) const {
442     return AttributeSets.getParamDereferenceableOrNullBytes(ArgNo);
443   }
444 
445   /// Determine if the function does not access memory.
doesNotAccessMemory()446   bool doesNotAccessMemory() const {
447     return hasFnAttribute(Attribute::ReadNone);
448   }
setDoesNotAccessMemory()449   void setDoesNotAccessMemory() {
450     addFnAttr(Attribute::ReadNone);
451   }
452 
453   /// Determine if the function does not access or only reads memory.
onlyReadsMemory()454   bool onlyReadsMemory() const {
455     return doesNotAccessMemory() || hasFnAttribute(Attribute::ReadOnly);
456   }
setOnlyReadsMemory()457   void setOnlyReadsMemory() {
458     addFnAttr(Attribute::ReadOnly);
459   }
460 
461   /// Determine if the function does not access or only writes memory.
doesNotReadMemory()462   bool doesNotReadMemory() const {
463     return doesNotAccessMemory() || hasFnAttribute(Attribute::WriteOnly);
464   }
setDoesNotReadMemory()465   void setDoesNotReadMemory() {
466     addFnAttr(Attribute::WriteOnly);
467   }
468 
469   /// Determine if the call can access memmory only using pointers based
470   /// on its arguments.
onlyAccessesArgMemory()471   bool onlyAccessesArgMemory() const {
472     return hasFnAttribute(Attribute::ArgMemOnly);
473   }
setOnlyAccessesArgMemory()474   void setOnlyAccessesArgMemory() { addFnAttr(Attribute::ArgMemOnly); }
475 
476   /// Determine if the function may only access memory that is
477   ///  inaccessible from the IR.
onlyAccessesInaccessibleMemory()478   bool onlyAccessesInaccessibleMemory() const {
479     return hasFnAttribute(Attribute::InaccessibleMemOnly);
480   }
setOnlyAccessesInaccessibleMemory()481   void setOnlyAccessesInaccessibleMemory() {
482     addFnAttr(Attribute::InaccessibleMemOnly);
483   }
484 
485   /// Determine if the function may only access memory that is
486   ///  either inaccessible from the IR or pointed to by its arguments.
onlyAccessesInaccessibleMemOrArgMem()487   bool onlyAccessesInaccessibleMemOrArgMem() const {
488     return hasFnAttribute(Attribute::InaccessibleMemOrArgMemOnly);
489   }
setOnlyAccessesInaccessibleMemOrArgMem()490   void setOnlyAccessesInaccessibleMemOrArgMem() {
491     addFnAttr(Attribute::InaccessibleMemOrArgMemOnly);
492   }
493 
494   /// Determine if the function cannot return.
doesNotReturn()495   bool doesNotReturn() const {
496     return hasFnAttribute(Attribute::NoReturn);
497   }
setDoesNotReturn()498   void setDoesNotReturn() {
499     addFnAttr(Attribute::NoReturn);
500   }
501 
502   /// Determine if the function should not perform indirect branch tracking.
doesNoCfCheck()503   bool doesNoCfCheck() const { return hasFnAttribute(Attribute::NoCfCheck); }
504 
505   /// Determine if the function cannot unwind.
doesNotThrow()506   bool doesNotThrow() const {
507     return hasFnAttribute(Attribute::NoUnwind);
508   }
setDoesNotThrow()509   void setDoesNotThrow() {
510     addFnAttr(Attribute::NoUnwind);
511   }
512 
513   /// Determine if the call cannot be duplicated.
cannotDuplicate()514   bool cannotDuplicate() const {
515     return hasFnAttribute(Attribute::NoDuplicate);
516   }
setCannotDuplicate()517   void setCannotDuplicate() {
518     addFnAttr(Attribute::NoDuplicate);
519   }
520 
521   /// Determine if the call is convergent.
isConvergent()522   bool isConvergent() const {
523     return hasFnAttribute(Attribute::Convergent);
524   }
setConvergent()525   void setConvergent() {
526     addFnAttr(Attribute::Convergent);
527   }
setNotConvergent()528   void setNotConvergent() {
529     removeFnAttr(Attribute::Convergent);
530   }
531 
532   /// Determine if the call has sideeffects.
isSpeculatable()533   bool isSpeculatable() const {
534     return hasFnAttribute(Attribute::Speculatable);
535   }
setSpeculatable()536   void setSpeculatable() {
537     addFnAttr(Attribute::Speculatable);
538   }
539 
540   /// Determine if the function is known not to recurse, directly or
541   /// indirectly.
doesNotRecurse()542   bool doesNotRecurse() const {
543     return hasFnAttribute(Attribute::NoRecurse);
544   }
setDoesNotRecurse()545   void setDoesNotRecurse() {
546     addFnAttr(Attribute::NoRecurse);
547   }
548 
549   /// True if the ABI mandates (or the user requested) that this
550   /// function be in a unwind table.
hasUWTable()551   bool hasUWTable() const {
552     return hasFnAttribute(Attribute::UWTable);
553   }
setHasUWTable()554   void setHasUWTable() {
555     addFnAttr(Attribute::UWTable);
556   }
557 
558   /// True if this function needs an unwind table.
needsUnwindTableEntry()559   bool needsUnwindTableEntry() const {
560     return hasUWTable() || !doesNotThrow() || hasPersonalityFn();
561   }
562 
563   /// Determine if the function returns a structure through first
564   /// or second pointer argument.
hasStructRetAttr()565   bool hasStructRetAttr() const {
566     return AttributeSets.hasParamAttribute(0, Attribute::StructRet) ||
567            AttributeSets.hasParamAttribute(1, Attribute::StructRet);
568   }
569 
570   /// Determine if the parameter or return value is marked with NoAlias
571   /// attribute.
returnDoesNotAlias()572   bool returnDoesNotAlias() const {
573     return AttributeSets.hasAttribute(AttributeList::ReturnIndex,
574                                       Attribute::NoAlias);
575   }
setReturnDoesNotAlias()576   void setReturnDoesNotAlias() {
577     addAttribute(AttributeList::ReturnIndex, Attribute::NoAlias);
578   }
579 
580   /// Optimize this function for minimum size (-Oz).
optForMinSize()581   bool optForMinSize() const { return hasFnAttribute(Attribute::MinSize); }
582 
583   /// Optimize this function for size (-Os) or minimum size (-Oz).
optForSize()584   bool optForSize() const {
585     return hasFnAttribute(Attribute::OptimizeForSize) || optForMinSize();
586   }
587 
588   /// copyAttributesFrom - copy all additional attributes (those not needed to
589   /// create a Function) from the Function Src to this one.
590   void copyAttributesFrom(const Function *Src);
591 
592   /// deleteBody - This method deletes the body of the function, and converts
593   /// the linkage to external.
594   ///
deleteBody()595   void deleteBody() {
596     dropAllReferences();
597     setLinkage(ExternalLinkage);
598   }
599 
600   /// removeFromParent - This method unlinks 'this' from the containing module,
601   /// but does not delete it.
602   ///
603   void removeFromParent();
604 
605   /// eraseFromParent - This method unlinks 'this' from the containing module
606   /// and deletes it.
607   ///
608   void eraseFromParent();
609 
610   /// Steal arguments from another function.
611   ///
612   /// Drop this function's arguments and splice in the ones from \c Src.
613   /// Requires that this has no function body.
614   void stealArgumentListFrom(Function &Src);
615 
616   /// Get the underlying elements of the Function... the basic block list is
617   /// empty for external functions.
618   ///
getBasicBlockList()619   const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
getBasicBlockList()620         BasicBlockListType &getBasicBlockList()       { return BasicBlocks; }
621 
getSublistAccess(BasicBlock *)622   static BasicBlockListType Function::*getSublistAccess(BasicBlock*) {
623     return &Function::BasicBlocks;
624   }
625 
getEntryBlock()626   const BasicBlock       &getEntryBlock() const   { return front(); }
getEntryBlock()627         BasicBlock       &getEntryBlock()         { return front(); }
628 
629   //===--------------------------------------------------------------------===//
630   // Symbol Table Accessing functions...
631 
632   /// getSymbolTable() - Return the symbol table if any, otherwise nullptr.
633   ///
getValueSymbolTable()634   inline ValueSymbolTable *getValueSymbolTable() { return SymTab.get(); }
getValueSymbolTable()635   inline const ValueSymbolTable *getValueSymbolTable() const {
636     return SymTab.get();
637   }
638 
639   //===--------------------------------------------------------------------===//
640   // BasicBlock iterator forwarding functions
641   //
begin()642   iterator                begin()       { return BasicBlocks.begin(); }
begin()643   const_iterator          begin() const { return BasicBlocks.begin(); }
end()644   iterator                end  ()       { return BasicBlocks.end();   }
end()645   const_iterator          end  () const { return BasicBlocks.end();   }
646 
size()647   size_t                   size() const { return BasicBlocks.size();  }
empty()648   bool                    empty() const { return BasicBlocks.empty(); }
front()649   const BasicBlock       &front() const { return BasicBlocks.front(); }
front()650         BasicBlock       &front()       { return BasicBlocks.front(); }
back()651   const BasicBlock        &back() const { return BasicBlocks.back();  }
back()652         BasicBlock        &back()       { return BasicBlocks.back();  }
653 
654 /// @name Function Argument Iteration
655 /// @{
656 
arg_begin()657   arg_iterator arg_begin() {
658     CheckLazyArguments();
659     return Arguments;
660   }
arg_begin()661   const_arg_iterator arg_begin() const {
662     CheckLazyArguments();
663     return Arguments;
664   }
665 
arg_end()666   arg_iterator arg_end() {
667     CheckLazyArguments();
668     return Arguments + NumArgs;
669   }
arg_end()670   const_arg_iterator arg_end() const {
671     CheckLazyArguments();
672     return Arguments + NumArgs;
673   }
674 
args()675   iterator_range<arg_iterator> args() {
676     return make_range(arg_begin(), arg_end());
677   }
args()678   iterator_range<const_arg_iterator> args() const {
679     return make_range(arg_begin(), arg_end());
680   }
681 
682 /// @}
683 
arg_size()684   size_t arg_size() const { return NumArgs; }
arg_empty()685   bool arg_empty() const { return arg_size() == 0; }
686 
687   /// Check whether this function has a personality function.
hasPersonalityFn()688   bool hasPersonalityFn() const {
689     return getSubclassDataFromValue() & (1<<3);
690   }
691 
692   /// Get the personality function associated with this function.
693   Constant *getPersonalityFn() const;
694   void setPersonalityFn(Constant *Fn);
695 
696   /// Check whether this function has prefix data.
hasPrefixData()697   bool hasPrefixData() const {
698     return getSubclassDataFromValue() & (1<<1);
699   }
700 
701   /// Get the prefix data associated with this function.
702   Constant *getPrefixData() const;
703   void setPrefixData(Constant *PrefixData);
704 
705   /// Check whether this function has prologue data.
hasPrologueData()706   bool hasPrologueData() const {
707     return getSubclassDataFromValue() & (1<<2);
708   }
709 
710   /// Get the prologue data associated with this function.
711   Constant *getPrologueData() const;
712   void setPrologueData(Constant *PrologueData);
713 
714   /// Print the function to an output stream with an optional
715   /// AssemblyAnnotationWriter.
716   void print(raw_ostream &OS, AssemblyAnnotationWriter *AAW = nullptr,
717              bool ShouldPreserveUseListOrder = false,
718              bool IsForDebug = false) const;
719 
720   /// viewCFG - This function is meant for use from the debugger.  You can just
721   /// say 'call F->viewCFG()' and a ghostview window should pop up from the
722   /// program, displaying the CFG of the current function with the code for each
723   /// basic block inside.  This depends on there being a 'dot' and 'gv' program
724   /// in your path.
725   ///
726   void viewCFG() const;
727 
728   /// viewCFGOnly - This function is meant for use from the debugger.  It works
729   /// just like viewCFG, but it does not include the contents of basic blocks
730   /// into the nodes, just the label.  If you are only interested in the CFG
731   /// this can make the graph smaller.
732   ///
733   void viewCFGOnly() const;
734 
735   /// Methods for support type inquiry through isa, cast, and dyn_cast:
classof(const Value * V)736   static bool classof(const Value *V) {
737     return V->getValueID() == Value::FunctionVal;
738   }
739 
740   /// dropAllReferences() - This method causes all the subinstructions to "let
741   /// go" of all references that they are maintaining.  This allows one to
742   /// 'delete' a whole module at a time, even though there may be circular
743   /// references... first all references are dropped, and all use counts go to
744   /// zero.  Then everything is deleted for real.  Note that no operations are
745   /// valid on an object that has "dropped all references", except operator
746   /// delete.
747   ///
748   /// Since no other object in the module can have references into the body of a
749   /// function, dropping all references deletes the entire body of the function,
750   /// including any contained basic blocks.
751   ///
752   void dropAllReferences();
753 
754   /// hasAddressTaken - returns true if there are any uses of this function
755   /// other than direct calls or invokes to it, or blockaddress expressions.
756   /// Optionally passes back an offending user for diagnostic purposes.
757   ///
758   bool hasAddressTaken(const User** = nullptr) const;
759 
760   /// isDefTriviallyDead - Return true if it is trivially safe to remove
761   /// this function definition from the module (because it isn't externally
762   /// visible, does not have its address taken, and has no callers).  To make
763   /// this more accurate, call removeDeadConstantUsers first.
764   bool isDefTriviallyDead() const;
765 
766   /// callsFunctionThatReturnsTwice - Return true if the function has a call to
767   /// setjmp or other function that gcc recognizes as "returning twice".
768   bool callsFunctionThatReturnsTwice() const;
769 
770   /// Set the attached subprogram.
771   ///
772   /// Calls \a setMetadata() with \a LLVMContext::MD_dbg.
773   void setSubprogram(DISubprogram *SP);
774 
775   /// Get the attached subprogram.
776   ///
777   /// Calls \a getMetadata() with \a LLVMContext::MD_dbg and casts the result
778   /// to \a DISubprogram.
779   DISubprogram *getSubprogram() const;
780 
781   /// Returns true if we should emit debug info for profiling.
782   bool isDebugInfoForProfiling() const;
783 
784   /// Check if null pointer dereferencing is considered undefined behavior for
785   /// the function.
786   /// Return value: false => null pointer dereference is undefined.
787   /// Return value: true =>  null pointer dereference is not undefined.
788   bool nullPointerIsDefined() const;
789 
790 private:
791   void allocHungoffUselist();
792   template<int Idx> void setHungoffOperand(Constant *C);
793 
794   /// Shadow Value::setValueSubclassData with a private forwarding method so
795   /// that subclasses cannot accidentally use it.
setValueSubclassData(unsigned short D)796   void setValueSubclassData(unsigned short D) {
797     Value::setValueSubclassData(D);
798   }
799   void setValueSubclassDataBit(unsigned Bit, bool On);
800 };
801 
802 /// Check whether null pointer dereferencing is considered undefined behavior
803 /// for a given function or an address space.
804 /// Null pointer access in non-zero address space is not considered undefined.
805 /// Return value: false => null pointer dereference is undefined.
806 /// Return value: true =>  null pointer dereference is not undefined.
807 bool NullPointerIsDefined(const Function *F, unsigned AS = 0);
808 
809 template <>
810 struct OperandTraits<Function> : public HungoffOperandTraits<3> {};
811 
812 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(Function, Value)
813 
814 } // end namespace llvm
815 
816 #endif // LLVM_IR_FUNCTION_H
817