text: //===--- Devirtualize.h - Helper for devirtualizing apply -------*- C++ -*-===//
  //
  // This source file is part of the Swift.org open source project
  //
  // Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
  // Licensed under Apache License v2.0 with Runtime Library Exception
  //
  // See https://swift.org/LICENSE.txt for license information
  // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
  //
  //===----------------------------------------------------------------------===//
  //
  // This contains helper functions that perform the work of devirtualizing a
  // given apply when possible.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef SWIFT_SIL_DEVIRTUALIZE_H
  #define SWIFT_SIL_DEVIRTUALIZE_H
  
  #include "swift/AST/Decl.h"
  #include "swift/AST/Types.h"
  #include "swift/SIL/SILDeclRef.h"
  #include "swift/SIL/SILFunction.h"
  #include "swift/SIL/SILInstruction.h"
  #include "swift/SIL/SILModule.h"
  #include "swift/SIL/SILType.h"
  #include "swift/SIL/SILValue.h"
  #include "swift/SILOptimizer/Analysis/ClassHierarchyAnalysis.h"
  #include "swift/SILOptimizer/Utils/Local.h"
  #include "llvm/ADT/ArrayRef.h"
  
  namespace swift {
  /// A pair representing results of devirtualization.
  ///  - The first element is the value representing the result of the
  ///    devirtualized call.
  ///  - The second element is the new apply/try_apply instruction.
  /// If no devirtualization was possible, the pair:
  /// <nullptr, FullApplySite()> is returned.
  ///
  /// Two elements are required, because a result of the new devirtualized
  /// apply/try_apply instruction (second element) eventually needs to be
  /// casted to produce a properly typed value (first element).
  typedef std::pair<ValueBase *, ApplySite> DevirtualizationResult;
  
  DevirtualizationResult tryDevirtualizeApply(ApplySite AI,
                                              ClassHierarchyAnalysis *CHA);
  bool canDevirtualizeApply(FullApplySite AI, ClassHierarchyAnalysis *CHA);
  bool isNominalTypeWithUnboundGenericParameters(SILType Ty, SILModule &M);
  bool canDevirtualizeClassMethod(FullApplySite AI, SILType ClassInstanceType);
  SILFunction *getTargetClassMethod(SILModule &M, SILType ClassOrMetatypeType,
                                    MethodInst *MI);
  DevirtualizationResult devirtualizeClassMethod(FullApplySite AI,
                                                 SILValue ClassInstance);
  DevirtualizationResult tryDevirtualizeClassMethod(FullApplySite AI,
                                                    SILValue ClassInstance);
  DevirtualizationResult tryDevirtualizeWitnessMethod(ApplySite AI);
  }
  
  #endif
  