//===--- 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 {
namespace OptRemark {
class Emitter;
}

/// 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).
///
/// *NOTE* The reason why we use a ValueBase here instead of a SILInstruction is
/// that a devirtualization result may be a BB arg if there was a cast in
/// between optional types.
typedef std::pair<ValueBase *, ApplySite> DevirtualizationResult;

/// Compute all subclasses of a given class.
///
/// \p CHA class hierarchy analysis
/// \p CD class declaration
/// \p ClassType type of the instance
/// \p M SILModule
/// \p Subs a container to be used for storing the set of subclasses
void getAllSubclasses(ClassHierarchyAnalysis *CHA,
                      ClassDecl *CD,
                      SILType ClassType,
                      SILModule &M,
                      ClassHierarchyAnalysis::ClassList &Subs);

DevirtualizationResult tryDevirtualizeApply(ApplySite AI,
                                            ClassHierarchyAnalysis *CHA,
                                            OptRemark::Emitter *ORE = nullptr);
bool canDevirtualizeApply(FullApplySite AI, ClassHierarchyAnalysis *CHA);
bool isNominalTypeWithUnboundGenericParameters(SILType Ty, SILModule &M);
bool canDevirtualizeClassMethod(FullApplySite AI, SILType ClassInstanceType,
                                OptRemark::Emitter *ORE = nullptr);
SILFunction *getTargetClassMethod(SILModule &M, SILType ClassOrMetatypeType,
                                  MethodInst *MI);
DevirtualizationResult devirtualizeClassMethod(FullApplySite AI,
                                               SILValue ClassInstance,
                                               OptRemark::Emitter *ORE);
DevirtualizationResult tryDevirtualizeClassMethod(FullApplySite AI,
                                                  SILValue ClassInstance,
                                                  OptRemark::Emitter *ORE);
DevirtualizationResult
tryDevirtualizeWitnessMethod(ApplySite AI, OptRemark::Emitter *ORE);
}

#endif