include/llvm/IR/Function.h

   1 //===- llvm/Function.h - Class to represent a single function ---*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file contains the declaration of the Function class, which represents a
  10 // single function/procedure in LLVM.
  11 //
  12 // A function basically consists of a list of basic blocks, a list of arguments,
  13 // and a symbol table.
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #ifndef LLVM_IR_FUNCTION_H
  18 #define LLVM_IR_FUNCTION_H
  19
  20 #include "llvm/ADT/DenseSet.h"
  21 #include "llvm/ADT/StringRef.h"
  22 #include "llvm/ADT/Twine.h"
  23 #include "llvm/ADT/ilist_node.h"
  24 #include "llvm/ADT/iterator_range.h"
  25 #include "llvm/IR/Argument.h"
  26 #include "llvm/IR/Attributes.h"
  27 #include "llvm/IR/BasicBlock.h"
  28 #include "llvm/IR/CallingConv.h"
  29 #include "llvm/IR/DerivedTypes.h"
  30 #include "llvm/IR/GlobalObject.h"
  31 #include "llvm/IR/GlobalValue.h"
  32 #include "llvm/IR/OperandTraits.h"
  33 #include "llvm/IR/SymbolTableListTraits.h"
  34 #include "llvm/IR/Value.h"
  35 #include "llvm/Support/Casting.h"
  36 #include "llvm/Support/Compiler.h"
  37 #include <cassert>
  38 #include <cstddef>
  39 #include <cstdint>
  40 #include <memory>
  41 #include <string>
  42
  43 namespace llvm {
  44
  45 namespace Intrinsic {
  46 enum ID : unsigned;
  47 }
  48
  49 class AssemblyAnnotationWriter;
  50 class Constant;
  51 class DISubprogram;
  52 class LLVMContext;
  53 class Module;
  54 template <typename T> class Optional;
  55 class raw_ostream;
  56 class Type;
  57 class User;
  58
  59 class Function : public GlobalObject, public ilist_node<Function> {
  60 public:
  61   using BasicBlockListType = SymbolTableList<BasicBlock>;
  62
  63   // BasicBlock iterators...
  64   using iterator = BasicBlockListType::iterator;
  65   using const_iterator = BasicBlockListType::const_iterator;
  66
  67   using arg_iterator = Argument *;
  68   using const_arg_iterator = const Argument *;
  69
  70 private:
  71   // Important things that make up a function!
  72   BasicBlockListType BasicBlocks;         ///< The basic blocks
  73   mutable Argument *Arguments = nullptr;  ///< The formal arguments
  74   size_t NumArgs;
  75   std::unique_ptr<ValueSymbolTable>
  76       SymTab;                             ///< Symbol table of args/instructions
  77   AttributeList AttributeSets;            ///< Parameter attributes
  78
  79   /*
  80    * Value::SubclassData
  81    *
  82    * bit 0      : HasLazyArguments
  83    * bit 1      : HasPrefixData
  84    * bit 2      : HasPrologueData
  85    * bit 3      : HasPersonalityFn
  86    * bits 4-13  : CallingConvention
  87    * bits 14    : HasGC
  88    * bits 15 : [reserved]
  89    */
  90
  91   /// Bits from GlobalObject::GlobalObjectSubclassData.
  92   enum {
  93     /// Whether this function is materializable.
  94     IsMaterializableBit = 0,
  95   };
  96
  97   friend class SymbolTableListTraits<Function>;
  98
  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 public:
 104   bool hasLazyArguments() const {
 105     return getSubclassDataFromValue() & (1<<0);
 106   }
 107
 108 private:
 109   void CheckLazyArguments() const {
 110     if (hasLazyArguments())
 111       BuildLazyArguments();
 112   }
 113
 114   void BuildLazyArguments() const;
 115
 116   void clearArguments();
 117
 118   /// Function ctor - If the (optional) Module argument is specified, the
 119   /// function is automatically inserted into the end of the function list for
 120   /// the module.
 121   ///
 122   Function(FunctionType *Ty, LinkageTypes Linkage, unsigned AddrSpace,
 123            const Twine &N = "", Module *M = nullptr);
 124
 125 public:
 126   Function(const Function&) = delete;
 127   void operator=(const Function&) = delete;
 128   ~Function();
 129
 130   // This is here to help easily convert from FunctionT * (Function * or
 131   // MachineFunction *) in BlockFrequencyInfoImpl to Function * by calling
 132   // FunctionT->getFunction().
 133   const Function &getFunction() const { return *this; }
 134
 135   static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
 136                           unsigned AddrSpace, const Twine &N = "",
 137                           Module *M = nullptr) {
 138     return new Function(Ty, Linkage, AddrSpace, N, M);
 139   }
 140
 141   // TODO: remove this once all users have been updated to pass an AddrSpace
 142   static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
 143                           const Twine &N = "", Module *M = nullptr) {
 144     return new Function(Ty, Linkage, static_cast<unsigned>(-1), N, M);
 145   }
 146
 147   /// Creates a new function and attaches it to a module.
 148   ///
 149   /// Places the function in the program address space as specified
 150   /// by the module's data layout.
 151   static Function *Create(FunctionType *Ty, LinkageTypes Linkage,
 152                           const Twine &N, Module &M);
 153
 154   // Provide fast operand accessors.
 155   DECLARE_TRANSPARENT_OPERAND_ACCESSORS(Value);
 156
 157   /// Returns the number of non-debug IR instructions in this function.
 158   /// This is equivalent to the sum of the sizes of each basic block contained
 159   /// within this function.
 160   unsigned getInstructionCount() const;
 161
 162   /// Returns the FunctionType for me.
 163   FunctionType *getFunctionType() const {
 164     return cast<FunctionType>(getValueType());
 165   }
 166
 167   /// Returns the type of the ret val.
 168   Type *getReturnType() const { return getFunctionType()->getReturnType(); }
 169
 170   /// getContext - Return a reference to the LLVMContext associated with this
 171   /// function.
 172   LLVMContext &getContext() const;
 173
 174   /// isVarArg - Return true if this function takes a variable number of
 175   /// arguments.
 176   bool isVarArg() const { return getFunctionType()->isVarArg(); }
 177
 178   bool isMaterializable() const {
 179     return getGlobalObjectSubClassData() & (1 << IsMaterializableBit);
 180   }
 181   void setIsMaterializable(bool V) {
 182     unsigned Mask = 1 << IsMaterializableBit;
 183     setGlobalObjectSubClassData((~Mask & getGlobalObjectSubClassData()) |
 184                                 (V ? Mask : 0u));
 185   }
 186
 187   /// getIntrinsicID - This method returns the ID number of the specified
 188   /// function, or Intrinsic::not_intrinsic if the function is not an
 189   /// intrinsic, or if the pointer is null.  This value is always defined to be
 190   /// zero to allow easy checking for whether a function is intrinsic or not.
 191   /// The particular intrinsic functions which correspond to this value are
 192   /// defined in llvm/Intrinsics.h.
 193   Intrinsic::ID getIntrinsicID() const LLVM_READONLY { return IntID; }
 194
 195   /// isIntrinsic - Returns true if the function's name starts with "llvm.".
 196   /// It's possible for this function to return true while getIntrinsicID()
 197   /// returns Intrinsic::not_intrinsic!
 198   bool isIntrinsic() const { return HasLLVMReservedName; }
 199
 200   static Intrinsic::ID lookupIntrinsicID(StringRef Name);
 201
 202   /// Recalculate the ID for this function if it is an Intrinsic defined
 203   /// in llvm/Intrinsics.h.  Sets the intrinsic ID to Intrinsic::not_intrinsic
 204   /// if the name of this function does not match an intrinsic in that header.
 205   /// Note, this method does not need to be called directly, as it is called
 206   /// from Value::setName() whenever the name of this function changes.
 207   void recalculateIntrinsicID();
 208
 209   /// getCallingConv()/setCallingConv(CC) - These method get and set the
 210   /// calling convention of this function.  The enum values for the known
 211   /// calling conventions are defined in CallingConv.h.
 212   CallingConv::ID getCallingConv() const {
 213     return static_cast<CallingConv::ID>((getSubclassDataFromValue() >> 4) &
 214                                         CallingConv::MaxID);
 215   }
 216   void setCallingConv(CallingConv::ID CC) {
 217     auto ID = static_cast<unsigned>(CC);
 218     assert(!(ID & ~CallingConv::MaxID) && "Unsupported calling convention");
 219     setValueSubclassData((getSubclassDataFromValue() & 0xc00f) | (ID << 4));
 220   }
 221
 222   /// Return the attribute list for this Function.
 223   AttributeList getAttributes() const { return AttributeSets; }
 224
 225   /// Set the attribute list for this Function.
 226   void setAttributes(AttributeList Attrs) { AttributeSets = Attrs; }
 227
 228   /// Add function attributes to this function.
 229   void addFnAttr(Attribute::AttrKind Kind) {
 230     addAttribute(AttributeList::FunctionIndex, Kind);
 231   }
 232
 233   /// Add function attributes to this function.
 234   void addFnAttr(StringRef Kind, StringRef Val = StringRef()) {
 235     addAttribute(AttributeList::FunctionIndex,
 236                  Attribute::get(getContext(), Kind, Val));
 237   }
 238
 239   /// Add function attributes to this function.
 240   void addFnAttr(Attribute Attr) {
 241     addAttribute(AttributeList::FunctionIndex, Attr);
 242   }
 243
 244   /// Remove function attributes from this function.
 245   void removeFnAttr(Attribute::AttrKind Kind) {
 246     removeAttribute(AttributeList::FunctionIndex, Kind);
 247   }
 248
 249   /// Remove function attribute from this function.
 250   void removeFnAttr(StringRef Kind) {
 251     setAttributes(getAttributes().removeAttribute(
 252         getContext(), AttributeList::FunctionIndex, Kind));
 253   }
 254
 255   enum ProfileCountType { PCT_Invalid, PCT_Real, PCT_Synthetic };
 256
 257   /// Class to represent profile counts.
 258   ///
 259   /// This class represents both real and synthetic profile counts.
 260   class ProfileCount {
 261   private:
 262     uint64_t Count;
 263     ProfileCountType PCT;
 264     static ProfileCount Invalid;
 265
 266   public:
 267     ProfileCount() : Count(-1), PCT(PCT_Invalid) {}
 268     ProfileCount(uint64_t Count, ProfileCountType PCT)
 269         : Count(Count), PCT(PCT) {}
 270     bool hasValue() const { return PCT != PCT_Invalid; }
 271     uint64_t getCount() const { return Count; }
 272     ProfileCountType getType() const { return PCT; }
 273     bool isSynthetic() const { return PCT == PCT_Synthetic; }
 274     explicit operator bool() { return hasValue(); }
 275     bool operator!() const { return !hasValue(); }
 276     // Update the count retaining the same profile count type.
 277     ProfileCount &setCount(uint64_t C) {
 278       Count = C;
 279       return *this;
 280     }
 281     static ProfileCount getInvalid() { return ProfileCount(-1, PCT_Invalid); }
 282   };
 283
 284   /// Set the entry count for this function.
 285   ///
 286   /// Entry count is the number of times this function was executed based on
 287   /// pgo data. \p Imports points to a set of GUIDs that needs to
 288   /// be imported by the function for sample PGO, to enable the same inlines as
 289   /// the profiled optimized binary.
 290   void setEntryCount(ProfileCount Count,
 291                      const DenseSet<GlobalValue::GUID> *Imports = nullptr);
 292
 293   /// A convenience wrapper for setting entry count
 294   void setEntryCount(uint64_t Count, ProfileCountType Type = PCT_Real,
 295                      const DenseSet<GlobalValue::GUID> *Imports = nullptr);
 296
 297   /// Get the entry count for this function.
 298   ///
 299   /// Entry count is the number of times the function was executed based on
 300   /// pgo data.
 301   ProfileCount getEntryCount() const;
 302
 303   /// Return true if the function is annotated with profile data.
 304   ///
 305   /// Presence of entry counts from a profile run implies the function has
 306   /// profile annotations.
 307   bool hasProfileData() const { return getEntryCount().hasValue(); }
 308
 309   /// Returns the set of GUIDs that needs to be imported to the function for
 310   /// sample PGO, to enable the same inlines as the profiled optimized binary.
 311   DenseSet<GlobalValue::GUID> getImportGUIDs() const;
 312
 313   /// Set the section prefix for this function.
 314   void setSectionPrefix(StringRef Prefix);
 315
 316   /// Get the section prefix for this function.
 317   Optional<StringRef> getSectionPrefix() const;
 318
 319   /// Return true if the function has the attribute.
 320   bool hasFnAttribute(Attribute::AttrKind Kind) const {
 321     return AttributeSets.hasFnAttribute(Kind);
 322   }
 323
 324   /// Return true if the function has the attribute.
 325   bool hasFnAttribute(StringRef Kind) const {
 326     return AttributeSets.hasFnAttribute(Kind);
 327   }
 328
 329   /// Return the attribute for the given attribute kind.
 330   Attribute getFnAttribute(Attribute::AttrKind Kind) const {
 331     return getAttribute(AttributeList::FunctionIndex, Kind);
 332   }
 333
 334   /// Return the attribute for the given attribute kind.
 335   Attribute getFnAttribute(StringRef Kind) const {
 336     return getAttribute(AttributeList::FunctionIndex, Kind);
 337   }
 338
 339   /// Return the stack alignment for the function.
 340   unsigned getFnStackAlignment() const {
 341     if (!hasFnAttribute(Attribute::StackAlignment))
 342       return 0;
 343     return AttributeSets.getStackAlignment(AttributeList::FunctionIndex);
 344   }
 345
 346   /// hasGC/getGC/setGC/clearGC - The name of the garbage collection algorithm
 347   ///                             to use during code generation.
 348   bool hasGC() const {
 349     return getSubclassDataFromValue() & (1<<14);
 350   }
 351   const std::string &getGC() const;
 352   void setGC(std::string Str);
 353   void clearGC();
 354
 355   /// adds the attribute to the list of attributes.
 356   void addAttribute(unsigned i, Attribute::AttrKind Kind);
 357
 358   /// adds the attribute to the list of attributes.
 359   void addAttribute(unsigned i, Attribute Attr);
 360
 361   /// adds the attributes to the list of attributes.
 362   void addAttributes(unsigned i, const AttrBuilder &Attrs);
 363
 364   /// adds the attribute to the list of attributes for the given arg.
 365   void addParamAttr(unsigned ArgNo, Attribute::AttrKind Kind);
 366
 367   /// adds the attribute to the list of attributes for the given arg.
 368   void addParamAttr(unsigned ArgNo, Attribute Attr);
 369
 370   /// adds the attributes to the list of attributes for the given arg.
 371   void addParamAttrs(unsigned ArgNo, const AttrBuilder &Attrs);
 372
 373   /// removes the attribute from the list of attributes.
 374   void removeAttribute(unsigned i, Attribute::AttrKind Kind);
 375
 376   /// removes the attribute from the list of attributes.
 377   void removeAttribute(unsigned i, StringRef Kind);
 378
 379   /// removes the attributes from the list of attributes.
 380   void removeAttributes(unsigned i, const AttrBuilder &Attrs);
 381
 382   /// removes the attribute from the list of attributes.
 383   void removeParamAttr(unsigned ArgNo, Attribute::AttrKind Kind);
 384
 385   /// removes the attribute from the list of attributes.
 386   void removeParamAttr(unsigned ArgNo, StringRef Kind);
 387
 388   /// removes the attribute from the list of attributes.
 389   void removeParamAttrs(unsigned ArgNo, const AttrBuilder &Attrs);
 390
 391   /// check if an attributes is in the list of attributes.
 392   bool hasAttribute(unsigned i, Attribute::AttrKind Kind) const {
 393     return getAttributes().hasAttribute(i, Kind);
 394   }
 395
 396   /// check if an attributes is in the list of attributes.
 397   bool hasParamAttribute(unsigned ArgNo, Attribute::AttrKind Kind) const {
 398     return getAttributes().hasParamAttribute(ArgNo, Kind);
 399   }
 400
 401   /// gets the attribute from the list of attributes.
 402   Attribute getAttribute(unsigned i, Attribute::AttrKind Kind) const {
 403     return AttributeSets.getAttribute(i, Kind);
 404   }
 405
 406   /// gets the attribute from the list of attributes.
 407   Attribute getAttribute(unsigned i, StringRef Kind) const {
 408     return AttributeSets.getAttribute(i, Kind);
 409   }
 410
 411   /// adds the dereferenceable attribute to the list of attributes.
 412   void addDereferenceableAttr(unsigned i, uint64_t Bytes);
 413
 414   /// adds the dereferenceable attribute to the list of attributes for
 415   /// the given arg.
 416   void addDereferenceableParamAttr(unsigned ArgNo, uint64_t Bytes);
 417
 418   /// adds the dereferenceable_or_null attribute to the list of
 419   /// attributes.
 420   void addDereferenceableOrNullAttr(unsigned i, uint64_t Bytes);
 421
 422   /// adds the dereferenceable_or_null attribute to the list of
 423   /// attributes for the given arg.
 424   void addDereferenceableOrNullParamAttr(unsigned ArgNo, uint64_t Bytes);
 425
 426   /// Extract the alignment for a call or parameter (0=unknown).
 427   unsigned getParamAlignment(unsigned ArgNo) const {
 428     return AttributeSets.getParamAlignment(ArgNo);
 429   }
 430
 431   /// Extract the number of dereferenceable bytes for a call or
 432   /// parameter (0=unknown).
 433   /// @param i AttributeList index, referring to a return value or argument.
 434   uint64_t getDereferenceableBytes(unsigned i) const {
 435     return AttributeSets.getDereferenceableBytes(i);
 436   }
 437
 438   /// Extract the number of dereferenceable bytes for a parameter.
 439   /// @param ArgNo Index of an argument, with 0 being the first function arg.
 440   uint64_t getParamDereferenceableBytes(unsigned ArgNo) const {
 441     return AttributeSets.getParamDereferenceableBytes(ArgNo);
 442   }
 443
 444   /// Extract the number of dereferenceable_or_null bytes for a call or
 445   /// parameter (0=unknown).
 446   /// @param i AttributeList index, referring to a return value or argument.
 447   uint64_t getDereferenceableOrNullBytes(unsigned i) const {
 448     return AttributeSets.getDereferenceableOrNullBytes(i);
 449   }
 450
 451   /// Extract the number of dereferenceable_or_null bytes for a
 452   /// parameter.
 453   /// @param ArgNo AttributeList ArgNo, referring to an argument.
 454   uint64_t getParamDereferenceableOrNullBytes(unsigned ArgNo) const {
 455     return AttributeSets.getParamDereferenceableOrNullBytes(ArgNo);
 456   }
 457
 458   /// Determine if the function does not access memory.
 459   bool doesNotAccessMemory() const {
 460     return hasFnAttribute(Attribute::ReadNone);
 461   }
 462   void setDoesNotAccessMemory() {
 463     addFnAttr(Attribute::ReadNone);
 464   }
 465
 466   /// Determine if the function does not access or only reads memory.
 467   bool onlyReadsMemory() const {
 468     return doesNotAccessMemory() || hasFnAttribute(Attribute::ReadOnly);
 469   }
 470   void setOnlyReadsMemory() {
 471     addFnAttr(Attribute::ReadOnly);
 472   }
 473
 474   /// Determine if the function does not access or only writes memory.
 475   bool doesNotReadMemory() const {
 476     return doesNotAccessMemory() || hasFnAttribute(Attribute::WriteOnly);
 477   }
 478   void setDoesNotReadMemory() {
 479     addFnAttr(Attribute::WriteOnly);
 480   }
 481
 482   /// Determine if the call can access memmory only using pointers based
 483   /// on its arguments.
 484   bool onlyAccessesArgMemory() const {
 485     return hasFnAttribute(Attribute::ArgMemOnly);
 486   }
 487   void setOnlyAccessesArgMemory() { addFnAttr(Attribute::ArgMemOnly); }
 488
 489   /// Determine if the function may only access memory that is
 490   ///  inaccessible from the IR.
 491   bool onlyAccessesInaccessibleMemory() const {
 492     return hasFnAttribute(Attribute::InaccessibleMemOnly);
 493   }
 494   void setOnlyAccessesInaccessibleMemory() {
 495     addFnAttr(Attribute::InaccessibleMemOnly);
 496   }
 497
 498   /// Determine if the function may only access memory that is
 499   ///  either inaccessible from the IR or pointed to by its arguments.
 500   bool onlyAccessesInaccessibleMemOrArgMem() const {
 501     return hasFnAttribute(Attribute::InaccessibleMemOrArgMemOnly);
 502   }
 503   void setOnlyAccessesInaccessibleMemOrArgMem() {
 504     addFnAttr(Attribute::InaccessibleMemOrArgMemOnly);
 505   }
 506
 507   /// Determine if the function cannot return.
 508   bool doesNotReturn() const {
 509     return hasFnAttribute(Attribute::NoReturn);
 510   }
 511   void setDoesNotReturn() {
 512     addFnAttr(Attribute::NoReturn);
 513   }
 514
 515   /// Determine if the function should not perform indirect branch tracking.
 516   bool doesNoCfCheck() const { return hasFnAttribute(Attribute::NoCfCheck); }
 517
 518   /// Determine if the function cannot unwind.
 519   bool doesNotThrow() const {
 520     return hasFnAttribute(Attribute::NoUnwind);
 521   }
 522   void setDoesNotThrow() {
 523     addFnAttr(Attribute::NoUnwind);
 524   }
 525
 526   /// Determine if the call cannot be duplicated.
 527   bool cannotDuplicate() const {
 528     return hasFnAttribute(Attribute::NoDuplicate);
 529   }
 530   void setCannotDuplicate() {
 531     addFnAttr(Attribute::NoDuplicate);
 532   }
 533
 534   /// Determine if the call is convergent.
 535   bool isConvergent() const {
 536     return hasFnAttribute(Attribute::Convergent);
 537   }
 538   void setConvergent() {
 539     addFnAttr(Attribute::Convergent);
 540   }
 541   void setNotConvergent() {
 542     removeFnAttr(Attribute::Convergent);
 543   }
 544
 545   /// Determine if the call has sideeffects.
 546   bool isSpeculatable() const {
 547     return hasFnAttribute(Attribute::Speculatable);
 548   }
 549   void setSpeculatable() {
 550     addFnAttr(Attribute::Speculatable);
 551   }
 552
 553   /// Determine if the function is known not to recurse, directly or
 554   /// indirectly.
 555   bool doesNotRecurse() const {
 556     return hasFnAttribute(Attribute::NoRecurse);
 557   }
 558   void setDoesNotRecurse() {
 559     addFnAttr(Attribute::NoRecurse);
 560   }
 561
 562   /// True if the ABI mandates (or the user requested) that this
 563   /// function be in a unwind table.
 564   bool hasUWTable() const {
 565     return hasFnAttribute(Attribute::UWTable);
 566   }
 567   void setHasUWTable() {
 568     addFnAttr(Attribute::UWTable);
 569   }
 570
 571   /// True if this function needs an unwind table.
 572   bool needsUnwindTableEntry() const {
 573     return hasUWTable() || !doesNotThrow() || hasPersonalityFn();
 574   }
 575
 576   /// Determine if the function returns a structure through first
 577   /// or second pointer argument.
 578   bool hasStructRetAttr() const {
 579     return AttributeSets.hasParamAttribute(0, Attribute::StructRet) ||
 580            AttributeSets.hasParamAttribute(1, Attribute::StructRet);
 581   }
 582
 583   /// Determine if the parameter or return value is marked with NoAlias
 584   /// attribute.
 585   bool returnDoesNotAlias() const {
 586     return AttributeSets.hasAttribute(AttributeList::ReturnIndex,
 587                                       Attribute::NoAlias);
 588   }
 589   void setReturnDoesNotAlias() {
 590     addAttribute(AttributeList::ReturnIndex, Attribute::NoAlias);
 591   }
 592
 593   /// Optimize this function for minimum size (-Oz).
 594   bool optForMinSize() const { return hasFnAttribute(Attribute::MinSize); }
 595
 596   /// Optimize this function for size (-Os) or minimum size (-Oz).
 597   bool optForSize() const {
 598     return hasFnAttribute(Attribute::OptimizeForSize) || optForMinSize();
 599   }
 600
 601   /// copyAttributesFrom - copy all additional attributes (those not needed to
 602   /// create a Function) from the Function Src to this one.
 603   void copyAttributesFrom(const Function *Src);
 604
 605   /// deleteBody - This method deletes the body of the function, and converts
 606   /// the linkage to external.
 607   ///
 608   void deleteBody() {
 609     dropAllReferences();
 610     setLinkage(ExternalLinkage);
 611   }
 612
 613   /// removeFromParent - This method unlinks 'this' from the containing module,
 614   /// but does not delete it.
 615   ///
 616   void removeFromParent();
 617
 618   /// eraseFromParent - This method unlinks 'this' from the containing module
 619   /// and deletes it.
 620   ///
 621   void eraseFromParent();
 622
 623   /// Steal arguments from another function.
 624   ///
 625   /// Drop this function's arguments and splice in the ones from \c Src.
 626   /// Requires that this has no function body.
 627   void stealArgumentListFrom(Function &Src);
 628
 629   /// Get the underlying elements of the Function... the basic block list is
 630   /// empty for external functions.
 631   ///
 632   const BasicBlockListType &getBasicBlockList() const { return BasicBlocks; }
 633         BasicBlockListType &getBasicBlockList()       { return BasicBlocks; }
 634
 635   static BasicBlockListType Function::*getSublistAccess(BasicBlock*) {
 636     return &Function::BasicBlocks;
 637   }
 638
 639   const BasicBlock       &getEntryBlock() const   { return front(); }
 640         BasicBlock       &getEntryBlock()         { return front(); }
 641
 642   //===--------------------------------------------------------------------===//
 643   // Symbol Table Accessing functions...
 644
 645   /// getSymbolTable() - Return the symbol table if any, otherwise nullptr.
 646   ///
 647   inline ValueSymbolTable *getValueSymbolTable() { return SymTab.get(); }
 648   inline const ValueSymbolTable *getValueSymbolTable() const {
 649     return SymTab.get();
 650   }
 651
 652   //===--------------------------------------------------------------------===//
 653   // BasicBlock iterator forwarding functions
 654   //
 655   iterator                begin()       { return BasicBlocks.begin(); }
 656   const_iterator          begin() const { return BasicBlocks.begin(); }
 657   iterator                end  ()       { return BasicBlocks.end();   }
 658   const_iterator          end  () const { return BasicBlocks.end();   }
 659
 660   size_t                   size() const { return BasicBlocks.size();  }
 661   bool                    empty() const { return BasicBlocks.empty(); }
 662   const BasicBlock       &front() const { return BasicBlocks.front(); }
 663         BasicBlock       &front()       { return BasicBlocks.front(); }
 664   const BasicBlock        &back() const { return BasicBlocks.back();  }
 665         BasicBlock        &back()       { return BasicBlocks.back();  }
 666
 667 /// @name Function Argument Iteration
 668 /// @{
 669
 670   arg_iterator arg_begin() {
 671     CheckLazyArguments();
 672     return Arguments;
 673   }
 674   const_arg_iterator arg_begin() const {
 675     CheckLazyArguments();
 676     return Arguments;
 677   }
 678
 679   arg_iterator arg_end() {
 680     CheckLazyArguments();
 681     return Arguments + NumArgs;
 682   }
 683   const_arg_iterator arg_end() const {
 684     CheckLazyArguments();
 685     return Arguments + NumArgs;
 686   }
 687
 688   iterator_range<arg_iterator> args() {
 689     return make_range(arg_begin(), arg_end());
 690   }
 691   iterator_range<const_arg_iterator> args() const {
 692     return make_range(arg_begin(), arg_end());
 693   }
 694
 695 /// @}
 696
 697   size_t arg_size() const { return NumArgs; }
 698   bool arg_empty() const { return arg_size() == 0; }
 699
 700   /// Check whether this function has a personality function.
 701   bool hasPersonalityFn() const {
 702     return getSubclassDataFromValue() & (1<<3);
 703   }
 704
 705   /// Get the personality function associated with this function.
 706   Constant *getPersonalityFn() const;
 707   void setPersonalityFn(Constant *Fn);
 708
 709   /// Check whether this function has prefix data.
 710   bool hasPrefixData() const {
 711     return getSubclassDataFromValue() & (1<<1);
 712   }
 713
 714   /// Get the prefix data associated with this function.
 715   Constant *getPrefixData() const;
 716   void setPrefixData(Constant *PrefixData);
 717
 718   /// Check whether this function has prologue data.
 719   bool hasPrologueData() const {
 720     return getSubclassDataFromValue() & (1<<2);
 721   }
 722
 723   /// Get the prologue data associated with this function.
 724   Constant *getPrologueData() const;
 725   void setPrologueData(Constant *PrologueData);
 726
 727   /// Print the function to an output stream with an optional
 728   /// AssemblyAnnotationWriter.
 729   void print(raw_ostream &OS, AssemblyAnnotationWriter *AAW = nullptr,
 730              bool ShouldPreserveUseListOrder = false,
 731              bool IsForDebug = false) const;
 732
 733   /// viewCFG - This function is meant for use from the debugger.  You can just
 734   /// say 'call F->viewCFG()' and a ghostview window should pop up from the
 735   /// program, displaying the CFG of the current function with the code for each
 736   /// basic block inside.  This depends on there being a 'dot' and 'gv' program
 737   /// in your path.
 738   ///
 739   void viewCFG() const;
 740
 741   /// viewCFGOnly - This function is meant for use from the debugger.  It works
 742   /// just like viewCFG, but it does not include the contents of basic blocks
 743   /// into the nodes, just the label.  If you are only interested in the CFG
 744   /// this can make the graph smaller.
 745   ///
 746   void viewCFGOnly() const;
 747
 748   /// Methods for support type inquiry through isa, cast, and dyn_cast:
 749   static bool classof(const Value *V) {
 750     return V->getValueID() == Value::FunctionVal;
 751   }
 752
 753   /// dropAllReferences() - This method causes all the subinstructions to "let
 754   /// go" of all references that they are maintaining.  This allows one to
 755   /// 'delete' a whole module at a time, even though there may be circular
 756   /// references... first all references are dropped, and all use counts go to
 757   /// zero.  Then everything is deleted for real.  Note that no operations are
 758   /// valid on an object that has "dropped all references", except operator
 759   /// delete.
 760   ///
 761   /// Since no other object in the module can have references into the body of a
 762   /// function, dropping all references deletes the entire body of the function,
 763   /// including any contained basic blocks.
 764   ///
 765   void dropAllReferences();
 766
 767   /// hasAddressTaken - returns true if there are any uses of this function
 768   /// other than direct calls or invokes to it, or blockaddress expressions.
 769   /// Optionally passes back an offending user for diagnostic purposes.
 770   ///
 771   bool hasAddressTaken(const User** = nullptr) const;
 772
 773   /// isDefTriviallyDead - Return true if it is trivially safe to remove
 774   /// this function definition from the module (because it isn't externally
 775   /// visible, does not have its address taken, and has no callers).  To make
 776   /// this more accurate, call removeDeadConstantUsers first.
 777   bool isDefTriviallyDead() const;
 778
 779   /// callsFunctionThatReturnsTwice - Return true if the function has a call to
 780   /// setjmp or other function that gcc recognizes as "returning twice".
 781   bool callsFunctionThatReturnsTwice() const;
 782
 783   /// Set the attached subprogram.
 784   ///
 785   /// Calls \a setMetadata() with \a LLVMContext::MD_dbg.
 786   void setSubprogram(DISubprogram *SP);
 787
 788   /// Get the attached subprogram.
 789   ///
 790   /// Calls \a getMetadata() with \a LLVMContext::MD_dbg and casts the result
 791   /// to \a DISubprogram.
 792   DISubprogram *getSubprogram() const;
 793
 794   /// Returns true if we should emit debug info for profiling.
 795   bool isDebugInfoForProfiling() const;
 796
 797   /// Check if null pointer dereferencing is considered undefined behavior for
 798   /// the function.
 799   /// Return value: false => null pointer dereference is undefined.
 800   /// Return value: true =>  null pointer dereference is not undefined.
 801   bool nullPointerIsDefined() const;
 802
 803 private:
 804   void allocHungoffUselist();
 805   template<int Idx> void setHungoffOperand(Constant *C);
 806
 807   /// Shadow Value::setValueSubclassData with a private forwarding method so
 808   /// that subclasses cannot accidentally use it.
 809   void setValueSubclassData(unsigned short D) {
 810     Value::setValueSubclassData(D);
 811   }
 812   void setValueSubclassDataBit(unsigned Bit, bool On);
 813 };
 814
 815 /// Check whether null pointer dereferencing is considered undefined behavior
 816 /// for a given function or an address space.
 817 /// Null pointer access in non-zero address space is not considered undefined.
 818 /// Return value: false => null pointer dereference is undefined.
 819 /// Return value: true =>  null pointer dereference is not undefined.
 820 bool NullPointerIsDefined(const Function *F, unsigned AS = 0);
 821
 822 template <>
 823 struct OperandTraits<Function> : public HungoffOperandTraits<3> {};
 824
 825 DEFINE_TRANSPARENT_OPERAND_ACCESSORS(Function, Value)
 826
 827 } // end namespace llvm
 828
 829 #endif // LLVM_IR_FUNCTION_H