include/swift/SIL/DynamicCasts.h - third_party/swift - Git at Google

 //===--- DynamicCasts.h - SIL dynamic-cast utilities ------------*- 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 file provides basic utilities for working with subtyping
 // relationships.
 //
 //===----------------------------------------------------------------------===//

 #ifndef SWIFT_SIL_DYNAMICCASTS_H
 #define SWIFT_SIL_DYNAMICCASTS_H

 #include "swift/AST/Module.h"
 #include "swift/Basic/ProfileCounter.h"
 #include "swift/SIL/SILInstruction.h"
 #include "swift/SIL/SILModule.h"
 #include "swift/SIL/SILValue.h"

 namespace swift {

 class CanType;
 class ModuleDecl;
 class SILBuilder;
 class SILLocation;
 class SILModule;
 class SILType;
 enum class CastConsumptionKind : unsigned char;
 struct SILDynamicCastInst;

 enum class DynamicCastFeasibility {
   /// The cast will always succeed.
   WillSucceed,

   /// The cast can succeed for some values.
   MaySucceed,

   /// The cast cannot succeed.
   WillFail,
 };

 static inline DynamicCastFeasibility
 atWorst(DynamicCastFeasibility feasibility, DynamicCastFeasibility worstCase) {
   return (feasibility > worstCase ? worstCase : feasibility);
 }

 static inline DynamicCastFeasibility
 atBest(DynamicCastFeasibility feasibility, DynamicCastFeasibility bestCase) {
   return (feasibility < bestCase ? bestCase : feasibility);
 }

 /// Classify the feasibility of a dynamic cast.  The source and target
 /// types should be unlowered formal types.
 DynamicCastFeasibility classifyDynamicCast(
     ModuleDecl *context,
     CanType sourceType, CanType targetType,
     bool isSourceTypeExact = false,
     bool isWholdModuleOpts = false);

 SILValue emitSuccessfulScalarUnconditionalCast(SILBuilder &B, SILLocation loc,
                                                SILDynamicCastInst inst);

 SILValue emitSuccessfulScalarUnconditionalCast(
     SILBuilder &B, ModuleDecl *M, SILLocation loc, SILValue value,
     SILType loweredTargetType,
     CanType formalSourceType, CanType formalTargetType,
     SILInstruction *existingCast = nullptr);

 bool emitSuccessfulIndirectUnconditionalCast(
     SILBuilder &B, ModuleDecl *M, SILLocation loc,
     SILValue src, CanType sourceType,
     SILValue dest, CanType targetType,
     SILInstruction *existingCast = nullptr);

 bool emitSuccessfulIndirectUnconditionalCast(SILBuilder &B, SILLocation loc,
                                              SILDynamicCastInst dynamicCast);

 /// Can the given cast be performed by the scalar checked-cast
 /// instructions, or does we need to use the indirect instructions?
 bool canUseScalarCheckedCastInstructions(SILModule &M,
                                          CanType sourceType,CanType targetType);

 /// Carry out the operations required for an indirect conditional cast
 /// using a scalar cast operation.
 void emitIndirectConditionalCastWithScalar(
     SILBuilder &B, ModuleDecl *M, SILLocation loc,
     CastConsumptionKind consumption, SILValue src, CanType sourceType,
     SILValue dest, CanType targetType, SILBasicBlock *trueBB,
     SILBasicBlock *falseBB, ProfileCounter TrueCount = ProfileCounter(),
     ProfileCounter FalseCount = ProfileCounter());

 /// Does the type conform to the _ObjectiveCBridgeable protocol.
 bool isObjectiveCBridgeable(ModuleDecl *M, CanType Ty);

 /// Get the bridged NS class of a CF class if it exists. Returns
 /// an empty CanType if such class does not exist.
 CanType getNSBridgedClassOfCFClass(ModuleDecl *M, CanType type);

 /// Does the type conform to Error.
 bool isError(ModuleDecl *M, CanType Ty);

 struct SILDynamicCastKind {
   enum innerty : std::underlying_type<SILInstructionKind>::type {
 #define DYNAMICCAST_INST(ID, PARENT) ID = unsigned(SILInstructionKind::ID),
 #include "swift/SIL/SILNodes.def"
   } value;

   explicit SILDynamicCastKind(SILInstructionKind kind) {
     auto newValue = SILDynamicCastKind::fromNodeKindHelper(kind);
     assert(newValue && "Non cast passed into SILDynamicCastKind");
     value = newValue.getValue();
   }

   SILDynamicCastKind(innerty value) : value(value) {}
   operator innerty() const { return value; }

   static Optional<SILDynamicCastKind> fromNodeKind(SILInstructionKind kind) {
     if (auto innerTyOpt = SILDynamicCastKind::fromNodeKindHelper(kind))
       return SILDynamicCastKind(*innerTyOpt);
     return None;
   }

 private:
   static Optional<innerty> fromNodeKindHelper(SILInstructionKind kind) {
     switch (kind) {
 #define DYNAMICCAST_INST(ID, PARENT)                                           \
   case SILInstructionKind::ID:                                                 \
     return SILDynamicCastKind::ID;
 #include "swift/SIL/SILNodes.def"
     default:
       return None;
     }
   }
 };

 struct SILDynamicCastInst {
   SILInstruction *inst;

 public:
   SILDynamicCastInst() : inst(nullptr) {}

   explicit SILDynamicCastInst(SILInstruction *inst) : inst(inst) {
     assert(classof(inst) && "not a dynamic cast?!");
   }

   static bool classof(const SILInstruction *inst) {
     return bool(SILDynamicCastKind::fromNodeKind(inst->getKind()));
   }

 #define DYNAMICCAST_INST(ID, PARENT)                                           \
   SILDynamicCastInst(ID *i) : inst(i) {}
 #include "swift/SIL/SILNodes.def"

   static SILDynamicCastInst getAs(SILNode *node) {
     auto *i = dyn_cast<SILInstruction>(node);
     if (!i)
       return SILDynamicCastInst();
     auto kind = SILDynamicCastKind::fromNodeKind(i->getKind());
     if (!kind)
       return SILDynamicCastInst();
     switch (kind.getValue()) {
 #define DYNAMICCAST_INST(ID, PARENT)                                           \
   case SILDynamicCastKind::ID:                                                 \
     return SILDynamicCastInst(cast<ID>(node));
 #include "swift/SIL/SILNodes.def"
     }
   }

   SILDynamicCastKind getKind() const {
     return SILDynamicCastKind(inst->getKind());
   }

   explicit operator bool() const { return inst != nullptr; }

   SILInstruction *getInstruction() const { return inst; }

   CastConsumptionKind getBridgedConsumptionKind() const {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastAddrBranchInst:
       return cast<CheckedCastAddrBranchInst>(inst)->getConsumptionKind();
     // TODO: Bridged casts cannot be expressed by checked_cast_br or
     // checked_cast_value_br yet. Should we ever support it, please
     // review this code.
     case SILDynamicCastKind::CheckedCastBranchInst:
     case SILDynamicCastKind::CheckedCastValueBranchInst:
       return CastConsumptionKind::CopyOnSuccess;
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
       return CastConsumptionKind::TakeAlways;
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
       return CastConsumptionKind::CopyOnSuccess;
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       llvm_unreachable("unsupported");
     }
     llvm_unreachable("covered switch");
   }

   CastConsumptionKind getConsumptionKind() const {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastAddrBranchInst:
     case SILDynamicCastKind::CheckedCastBranchInst:
     case SILDynamicCastKind::CheckedCastValueBranchInst:
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       llvm_unreachable("unsupported");
     }
   }

   SILBasicBlock *getSuccessBlock() {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastAddrBranchInst:
       return cast<CheckedCastAddrBranchInst>(inst)->getSuccessBB();
     case SILDynamicCastKind::CheckedCastBranchInst:
       return cast<CheckedCastBranchInst>(inst)->getSuccessBB();
     case SILDynamicCastKind::CheckedCastValueBranchInst:
       return cast<CheckedCastValueBranchInst>(inst)->getSuccessBB();
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
       return nullptr;
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       llvm_unreachable("unsupported");
     }
     llvm_unreachable("covered switch");
   }

   Optional<ProfileCounter> getSuccessBlockCount() {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastAddrBranchInst:
       llvm_unreachable("unsupported");
     case SILDynamicCastKind::CheckedCastBranchInst:
       return cast<CheckedCastBranchInst>(inst)->getTrueBBCount();
     case SILDynamicCastKind::CheckedCastValueBranchInst:
       llvm_unreachable("unsupported");
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
       return None;
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       llvm_unreachable("unsupported");
     }
     llvm_unreachable("covered switch");
   }

   const SILBasicBlock *getSuccessBlock() const {
     return const_cast<SILDynamicCastInst &>(*this).getSuccessBlock();
   }

   SILBasicBlock *getFailureBlock() {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastAddrBranchInst:
       return cast<CheckedCastAddrBranchInst>(inst)->getFailureBB();
     case SILDynamicCastKind::CheckedCastBranchInst:
       return cast<CheckedCastBranchInst>(inst)->getFailureBB();
     case SILDynamicCastKind::CheckedCastValueBranchInst:
       return cast<CheckedCastValueBranchInst>(inst)->getFailureBB();
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
       return nullptr;
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       llvm_unreachable("unsupported");
     }
     llvm_unreachable("covered switch");
   }

   Optional<ProfileCounter> getFailureBlockCount() {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastAddrBranchInst:
       llvm_unreachable("unsupported");
     case SILDynamicCastKind::CheckedCastBranchInst:
       return cast<CheckedCastBranchInst>(inst)->getFalseBBCount();
     case SILDynamicCastKind::CheckedCastValueBranchInst:
       llvm_unreachable("unsupported");
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
       return None;
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       llvm_unreachable("unsupported");
     }
     llvm_unreachable("covered switch");
   }

   const SILBasicBlock *getFailureBlock() const {
     return const_cast<SILDynamicCastInst &>(*this).getFailureBlock();
   }

   SILValue getSource() const {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastAddrBranchInst:
       return cast<CheckedCastAddrBranchInst>(inst)->getSrc();
     case SILDynamicCastKind::CheckedCastBranchInst:
       return cast<CheckedCastBranchInst>(inst)->getOperand();
     case SILDynamicCastKind::CheckedCastValueBranchInst:
       return cast<CheckedCastValueBranchInst>(inst)->getOperand();
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
       return cast<UnconditionalCheckedCastAddrInst>(inst)->getSrc();
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
       return cast<UnconditionalCheckedCastInst>(inst)->getOperand();
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       llvm_unreachable("unsupported");
     }
     llvm_unreachable("covered switch");
   }

   // Returns the success value.
   SILValue getDest() const {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastAddrBranchInst:
       return cast<CheckedCastAddrBranchInst>(inst)->getDest();
     case SILDynamicCastKind::CheckedCastBranchInst:
     case SILDynamicCastKind::CheckedCastValueBranchInst:
       // TODO: Shouldn't this return getSuccessBlock()->getArgument(0)?
       return SILValue();
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
       return cast<UnconditionalCheckedCastAddrInst>(inst)->getDest();
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
       // TODO: Why isn't this:
       //
       // return cast<UnconditionalCheckedCastInst>(inst);
       return SILValue();
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       llvm_unreachable("unimplemented");
     }
     llvm_unreachable("covered switch");
   }

   CanType getSourceFormalType() const {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastAddrBranchInst:
       return cast<CheckedCastAddrBranchInst>(inst)->getSourceFormalType();
     case SILDynamicCastKind::CheckedCastBranchInst:
       return cast<CheckedCastBranchInst>(inst)->getSourceFormalType();
     case SILDynamicCastKind::CheckedCastValueBranchInst:
       return cast<CheckedCastValueBranchInst>(inst)->getSourceFormalType();
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
       return cast<UnconditionalCheckedCastAddrInst>(inst)->getSourceFormalType();
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
       return cast<UnconditionalCheckedCastInst>(inst)->getSourceFormalType();
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       return cast<UnconditionalCheckedCastValueInst>(inst)->getSourceFormalType();
     }
     llvm_unreachable("covered switch");
   }

   SILType getSourceLoweredType() const {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastAddrBranchInst:
       return cast<CheckedCastAddrBranchInst>(inst)->getSourceLoweredType();
     case SILDynamicCastKind::CheckedCastBranchInst:
       return cast<CheckedCastBranchInst>(inst)->getSourceLoweredType();
     case SILDynamicCastKind::CheckedCastValueBranchInst:
       return cast<CheckedCastValueBranchInst>(inst)->getSourceLoweredType();
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
       return cast<UnconditionalCheckedCastAddrInst>(inst)->getSourceLoweredType();
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
       return cast<UnconditionalCheckedCastInst>(inst)->getSourceLoweredType();
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       return cast<UnconditionalCheckedCastValueInst>(inst)->getSourceLoweredType();
     }
   }

   CanType getTargetFormalType() const {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastAddrBranchInst:
       return cast<CheckedCastAddrBranchInst>(inst)->getTargetFormalType();
     case SILDynamicCastKind::CheckedCastBranchInst:
       return cast<CheckedCastBranchInst>(inst)->getTargetFormalType();
     case SILDynamicCastKind::CheckedCastValueBranchInst:
       return cast<CheckedCastValueBranchInst>(inst)->getTargetFormalType();
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
       return cast<UnconditionalCheckedCastAddrInst>(inst)->getTargetFormalType();
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
       return cast<UnconditionalCheckedCastInst>(inst)->getTargetFormalType();
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       return cast<UnconditionalCheckedCastValueInst>(inst)->getTargetFormalType();
     }
     llvm_unreachable("covered switch");
   }

   SILType getTargetLoweredType() const {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastAddrBranchInst:
       return cast<CheckedCastAddrBranchInst>(inst)->getDest()->getType();
     case SILDynamicCastKind::CheckedCastBranchInst:
       return cast<CheckedCastBranchInst>(inst)->getTargetLoweredType();
     case SILDynamicCastKind::CheckedCastValueBranchInst:
       return cast<CheckedCastValueBranchInst>(inst)->getTargetLoweredType();
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
       return cast<UnconditionalCheckedCastAddrInst>(inst)->getDest()->getType();
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
       return cast<UnconditionalCheckedCastInst>(inst)->getTargetLoweredType();
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       return cast<UnconditionalCheckedCastValueInst>(inst)->getTargetLoweredType();
     }
     llvm_unreachable("covered switch");
   }

   bool isSourceTypeExact() const {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastValueBranchInst:
     case SILDynamicCastKind::CheckedCastBranchInst:
     case SILDynamicCastKind::CheckedCastAddrBranchInst:
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
       return isa<MetatypeInst>(getSource());
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       llvm_unreachable("unsupported");
     }
     llvm_unreachable("covered switch");
   }

   SILLocation getLocation() const { return inst->getLoc(); }

   SILModule &getModule() const { return inst->getModule(); }
   SILFunction *getFunction() const { return inst->getFunction(); }

   DynamicCastFeasibility classifyFeasibility(bool allowWholeModule) const {
     return swift::classifyDynamicCast(
         getModule().getSwiftModule(),
         getSourceFormalType(), getTargetFormalType(),
         isSourceTypeExact(), allowWholeModule && getModule().isWholeModule());
   }

   bool isBridgingCast() const {
     // Bridging casts cannot be further simplified.
     auto TargetIsBridgeable = getTargetFormalType()->isBridgeableObjectType();
     auto SourceIsBridgeable = getSourceFormalType()->isBridgeableObjectType();
     return TargetIsBridgeable != SourceIsBridgeable;
   }

   /// Returns true if this dynamic cast can release its source operand.
   bool isRCIdentityPreserving() const;

   /// If getSourceType() is a Swift type that can bridge to an ObjC type, return
   /// the ObjC type it bridges to. If the source type is an objc type, an empty
   /// CanType() is returned.
   CanType getBridgedSourceType() const {
     SILModule &mod = getModule();
     Type t = mod.getASTContext().getBridgedToObjC(mod.getSwiftModule(),
                                                   getSourceFormalType());
     if (!t)
       return CanType();
     return t->getCanonicalType();
   }

   /// If getTargetType() is a Swift type that can bridge to an ObjC type, return
   /// the ObjC type it bridges to. If the target type is an objc type, an empty
   /// CanType() is returned.
   CanType getBridgedTargetType() const {
     SILModule &mod = getModule();
     Type t = mod.getASTContext().getBridgedToObjC(mod.getSwiftModule(),
                                                   getTargetFormalType());
     if (!t)
       return CanType();
     return t->getCanonicalType();
   }

   Optional<SILType> getLoweredBridgedTargetObjectType() const {
     CanType t = getBridgedTargetType();
     if (!t)
       return None;
     return SILType::getPrimitiveObjectType(t);
   }

   bool isConditional() const {
     switch (getKind()) {
     case SILDynamicCastKind::CheckedCastAddrBranchInst: {
       auto f = classifyFeasibility(true /*allow wmo*/);
       return f == DynamicCastFeasibility::MaySucceed;
     }
     case SILDynamicCastKind::CheckedCastBranchInst: {
       auto f = classifyFeasibility(false /*allow wmo*/);
       return f == DynamicCastFeasibility::MaySucceed;
     }
     case SILDynamicCastKind::CheckedCastValueBranchInst: {
       auto f = classifyFeasibility(false /*allow wmo opts*/);
       return f == DynamicCastFeasibility::MaySucceed;
     }
     case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
     case SILDynamicCastKind::UnconditionalCheckedCastInst:
       return false;
     case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
       llvm_unreachable("unsupported");
     }
     llvm_unreachable("covered switch");
   }

   bool canUseScalarCheckedCastInstructions() const {
     return swift::canUseScalarCheckedCastInstructions(
         getModule(), getSourceFormalType(), getTargetFormalType());
   }
 };

 } // end namespace swift

 #endif
	//===--- DynamicCasts.h - SIL dynamic-cast utilities ------------- 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 file provides basic utilities for working with subtyping
	// relationships.
	//
	//===----------------------------------------------------------------------===//

	#ifndef SWIFT_SIL_DYNAMICCASTS_H
	#define SWIFT_SIL_DYNAMICCASTS_H

	#include "swift/AST/Module.h"
	#include "swift/Basic/ProfileCounter.h"
	#include "swift/SIL/SILInstruction.h"
	#include "swift/SIL/SILModule.h"
	#include "swift/SIL/SILValue.h"

	namespace swift {

	class CanType;
	class ModuleDecl;
	class SILBuilder;
	class SILLocation;
	class SILModule;
	class SILType;
	enum class CastConsumptionKind : unsigned char;
	struct SILDynamicCastInst;

	enum class DynamicCastFeasibility {
	/// The cast will always succeed.
	WillSucceed,

	/// The cast can succeed for some values.
	MaySucceed,

	/// The cast cannot succeed.
	WillFail,
	};

	static inline DynamicCastFeasibility
	atWorst(DynamicCastFeasibility feasibility, DynamicCastFeasibility worstCase) {
	return (feasibility > worstCase ? worstCase : feasibility);
	}

	static inline DynamicCastFeasibility
	atBest(DynamicCastFeasibility feasibility, DynamicCastFeasibility bestCase) {
	return (feasibility < bestCase ? bestCase : feasibility);
	}

	/// Classify the feasibility of a dynamic cast. The source and target
	/// types should be unlowered formal types.
	DynamicCastFeasibility classifyDynamicCast(
	ModuleDecl *context,
	CanType sourceType, CanType targetType,
	bool isSourceTypeExact = false,
	bool isWholdModuleOpts = false);

	SILValue emitSuccessfulScalarUnconditionalCast(SILBuilder &B, SILLocation loc,
	SILDynamicCastInst inst);

	SILValue emitSuccessfulScalarUnconditionalCast(
	SILBuilder &B, ModuleDecl *M, SILLocation loc, SILValue value,
	SILType loweredTargetType,
	CanType formalSourceType, CanType formalTargetType,
	SILInstruction *existingCast = nullptr);

	bool emitSuccessfulIndirectUnconditionalCast(
	SILBuilder &B, ModuleDecl *M, SILLocation loc,
	SILValue src, CanType sourceType,
	SILValue dest, CanType targetType,
	SILInstruction *existingCast = nullptr);

	bool emitSuccessfulIndirectUnconditionalCast(SILBuilder &B, SILLocation loc,
	SILDynamicCastInst dynamicCast);

	/// Can the given cast be performed by the scalar checked-cast
	/// instructions, or does we need to use the indirect instructions?
	bool canUseScalarCheckedCastInstructions(SILModule &M,
	CanType sourceType,CanType targetType);

	/// Carry out the operations required for an indirect conditional cast
	/// using a scalar cast operation.
	void emitIndirectConditionalCastWithScalar(
	SILBuilder &B, ModuleDecl *M, SILLocation loc,
	CastConsumptionKind consumption, SILValue src, CanType sourceType,
	SILValue dest, CanType targetType, SILBasicBlock *trueBB,
	SILBasicBlock *falseBB, ProfileCounter TrueCount = ProfileCounter(),
	ProfileCounter FalseCount = ProfileCounter());

	/// Does the type conform to the _ObjectiveCBridgeable protocol.
	bool isObjectiveCBridgeable(ModuleDecl *M, CanType Ty);

	/// Get the bridged NS class of a CF class if it exists. Returns
	/// an empty CanType if such class does not exist.
	CanType getNSBridgedClassOfCFClass(ModuleDecl *M, CanType type);

	/// Does the type conform to Error.
	bool isError(ModuleDecl *M, CanType Ty);

	struct SILDynamicCastKind {
	enum innerty : std::underlying_type<SILInstructionKind>::type {
	#define DYNAMICCAST_INST(ID, PARENT) ID = unsigned(SILInstructionKind::ID),
	#include "swift/SIL/SILNodes.def"
	} value;

	explicit SILDynamicCastKind(SILInstructionKind kind) {
	auto newValue = SILDynamicCastKind::fromNodeKindHelper(kind);
	assert(newValue && "Non cast passed into SILDynamicCastKind");
	value = newValue.getValue();
	}

	SILDynamicCastKind(innerty value) : value(value) {}
	operator innerty() const { return value; }

	static Optional<SILDynamicCastKind> fromNodeKind(SILInstructionKind kind) {
	if (auto innerTyOpt = SILDynamicCastKind::fromNodeKindHelper(kind))
	return SILDynamicCastKind(*innerTyOpt);
	return None;
	}

	private:
	static Optional<innerty> fromNodeKindHelper(SILInstructionKind kind) {
	switch (kind) {
	#define DYNAMICCAST_INST(ID, PARENT) \
	case SILInstructionKind::ID: \
	return SILDynamicCastKind::ID;
	#include "swift/SIL/SILNodes.def"
	default:
	return None;
	}
	}
	};

	struct SILDynamicCastInst {
	SILInstruction *inst;

	public:
	SILDynamicCastInst() : inst(nullptr) {}

	explicit SILDynamicCastInst(SILInstruction *inst) : inst(inst) {
	assert(classof(inst) && "not a dynamic cast?!");
	}

	static bool classof(const SILInstruction *inst) {
	return bool(SILDynamicCastKind::fromNodeKind(inst->getKind()));
	}

	#define DYNAMICCAST_INST(ID, PARENT) \
	SILDynamicCastInst(ID *i) : inst(i) {}
	#include "swift/SIL/SILNodes.def"

	static SILDynamicCastInst getAs(SILNode *node) {
	auto *i = dyn_cast<SILInstruction>(node);
	if (!i)
	return SILDynamicCastInst();
	auto kind = SILDynamicCastKind::fromNodeKind(i->getKind());
	if (!kind)
	return SILDynamicCastInst();
	switch (kind.getValue()) {
	#define DYNAMICCAST_INST(ID, PARENT) \
	case SILDynamicCastKind::ID: \
	return SILDynamicCastInst(cast<ID>(node));
	#include "swift/SIL/SILNodes.def"
	}
	}

	SILDynamicCastKind getKind() const {
	return SILDynamicCastKind(inst->getKind());
	}

	explicit operator bool() const { return inst != nullptr; }

	SILInstruction *getInstruction() const { return inst; }

	CastConsumptionKind getBridgedConsumptionKind() const {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastAddrBranchInst:
	return cast<CheckedCastAddrBranchInst>(inst)->getConsumptionKind();
	// TODO: Bridged casts cannot be expressed by checked_cast_br or
	// checked_cast_value_br yet. Should we ever support it, please
	// review this code.
	case SILDynamicCastKind::CheckedCastBranchInst:
	case SILDynamicCastKind::CheckedCastValueBranchInst:
	return CastConsumptionKind::CopyOnSuccess;
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	return CastConsumptionKind::TakeAlways;
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	return CastConsumptionKind::CopyOnSuccess;
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	llvm_unreachable("unsupported");
	}
	llvm_unreachable("covered switch");
	}

	CastConsumptionKind getConsumptionKind() const {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastAddrBranchInst:
	case SILDynamicCastKind::CheckedCastBranchInst:
	case SILDynamicCastKind::CheckedCastValueBranchInst:
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	llvm_unreachable("unsupported");
	}
	}

	SILBasicBlock *getSuccessBlock() {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastAddrBranchInst:
	return cast<CheckedCastAddrBranchInst>(inst)->getSuccessBB();
	case SILDynamicCastKind::CheckedCastBranchInst:
	return cast<CheckedCastBranchInst>(inst)->getSuccessBB();
	case SILDynamicCastKind::CheckedCastValueBranchInst:
	return cast<CheckedCastValueBranchInst>(inst)->getSuccessBB();
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	return nullptr;
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	llvm_unreachable("unsupported");
	}
	llvm_unreachable("covered switch");
	}

	Optional<ProfileCounter> getSuccessBlockCount() {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastAddrBranchInst:
	llvm_unreachable("unsupported");
	case SILDynamicCastKind::CheckedCastBranchInst:
	return cast<CheckedCastBranchInst>(inst)->getTrueBBCount();
	case SILDynamicCastKind::CheckedCastValueBranchInst:
	llvm_unreachable("unsupported");
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	return None;
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	llvm_unreachable("unsupported");
	}
	llvm_unreachable("covered switch");
	}

	const SILBasicBlock *getSuccessBlock() const {
	return const_cast<SILDynamicCastInst &>(*this).getSuccessBlock();
	}

	SILBasicBlock *getFailureBlock() {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastAddrBranchInst:
	return cast<CheckedCastAddrBranchInst>(inst)->getFailureBB();
	case SILDynamicCastKind::CheckedCastBranchInst:
	return cast<CheckedCastBranchInst>(inst)->getFailureBB();
	case SILDynamicCastKind::CheckedCastValueBranchInst:
	return cast<CheckedCastValueBranchInst>(inst)->getFailureBB();
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	return nullptr;
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	llvm_unreachable("unsupported");
	}
	llvm_unreachable("covered switch");
	}

	Optional<ProfileCounter> getFailureBlockCount() {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastAddrBranchInst:
	llvm_unreachable("unsupported");
	case SILDynamicCastKind::CheckedCastBranchInst:
	return cast<CheckedCastBranchInst>(inst)->getFalseBBCount();
	case SILDynamicCastKind::CheckedCastValueBranchInst:
	llvm_unreachable("unsupported");
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	return None;
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	llvm_unreachable("unsupported");
	}
	llvm_unreachable("covered switch");
	}

	const SILBasicBlock *getFailureBlock() const {
	return const_cast<SILDynamicCastInst &>(*this).getFailureBlock();
	}

	SILValue getSource() const {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastAddrBranchInst:
	return cast<CheckedCastAddrBranchInst>(inst)->getSrc();
	case SILDynamicCastKind::CheckedCastBranchInst:
	return cast<CheckedCastBranchInst>(inst)->getOperand();
	case SILDynamicCastKind::CheckedCastValueBranchInst:
	return cast<CheckedCastValueBranchInst>(inst)->getOperand();
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	return cast<UnconditionalCheckedCastAddrInst>(inst)->getSrc();
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	return cast<UnconditionalCheckedCastInst>(inst)->getOperand();
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	llvm_unreachable("unsupported");
	}
	llvm_unreachable("covered switch");
	}

	// Returns the success value.
	SILValue getDest() const {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastAddrBranchInst:
	return cast<CheckedCastAddrBranchInst>(inst)->getDest();
	case SILDynamicCastKind::CheckedCastBranchInst:
	case SILDynamicCastKind::CheckedCastValueBranchInst:
	// TODO: Shouldn't this return getSuccessBlock()->getArgument(0)?
	return SILValue();
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	return cast<UnconditionalCheckedCastAddrInst>(inst)->getDest();
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	// TODO: Why isn't this:
	//
	// return cast<UnconditionalCheckedCastInst>(inst);
	return SILValue();
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	llvm_unreachable("unimplemented");
	}
	llvm_unreachable("covered switch");
	}

	CanType getSourceFormalType() const {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastAddrBranchInst:
	return cast<CheckedCastAddrBranchInst>(inst)->getSourceFormalType();
	case SILDynamicCastKind::CheckedCastBranchInst:
	return cast<CheckedCastBranchInst>(inst)->getSourceFormalType();
	case SILDynamicCastKind::CheckedCastValueBranchInst:
	return cast<CheckedCastValueBranchInst>(inst)->getSourceFormalType();
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	return cast<UnconditionalCheckedCastAddrInst>(inst)->getSourceFormalType();
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	return cast<UnconditionalCheckedCastInst>(inst)->getSourceFormalType();
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	return cast<UnconditionalCheckedCastValueInst>(inst)->getSourceFormalType();
	}
	llvm_unreachable("covered switch");
	}

	SILType getSourceLoweredType() const {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastAddrBranchInst:
	return cast<CheckedCastAddrBranchInst>(inst)->getSourceLoweredType();
	case SILDynamicCastKind::CheckedCastBranchInst:
	return cast<CheckedCastBranchInst>(inst)->getSourceLoweredType();
	case SILDynamicCastKind::CheckedCastValueBranchInst:
	return cast<CheckedCastValueBranchInst>(inst)->getSourceLoweredType();
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	return cast<UnconditionalCheckedCastAddrInst>(inst)->getSourceLoweredType();
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	return cast<UnconditionalCheckedCastInst>(inst)->getSourceLoweredType();
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	return cast<UnconditionalCheckedCastValueInst>(inst)->getSourceLoweredType();
	}
	}

	CanType getTargetFormalType() const {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastAddrBranchInst:
	return cast<CheckedCastAddrBranchInst>(inst)->getTargetFormalType();
	case SILDynamicCastKind::CheckedCastBranchInst:
	return cast<CheckedCastBranchInst>(inst)->getTargetFormalType();
	case SILDynamicCastKind::CheckedCastValueBranchInst:
	return cast<CheckedCastValueBranchInst>(inst)->getTargetFormalType();
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	return cast<UnconditionalCheckedCastAddrInst>(inst)->getTargetFormalType();
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	return cast<UnconditionalCheckedCastInst>(inst)->getTargetFormalType();
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	return cast<UnconditionalCheckedCastValueInst>(inst)->getTargetFormalType();
	}
	llvm_unreachable("covered switch");
	}

	SILType getTargetLoweredType() const {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastAddrBranchInst:
	return cast<CheckedCastAddrBranchInst>(inst)->getDest()->getType();
	case SILDynamicCastKind::CheckedCastBranchInst:
	return cast<CheckedCastBranchInst>(inst)->getTargetLoweredType();
	case SILDynamicCastKind::CheckedCastValueBranchInst:
	return cast<CheckedCastValueBranchInst>(inst)->getTargetLoweredType();
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	return cast<UnconditionalCheckedCastAddrInst>(inst)->getDest()->getType();
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	return cast<UnconditionalCheckedCastInst>(inst)->getTargetLoweredType();
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	return cast<UnconditionalCheckedCastValueInst>(inst)->getTargetLoweredType();
	}
	llvm_unreachable("covered switch");
	}

	bool isSourceTypeExact() const {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastValueBranchInst:
	case SILDynamicCastKind::CheckedCastBranchInst:
	case SILDynamicCastKind::CheckedCastAddrBranchInst:
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	return isa<MetatypeInst>(getSource());
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	llvm_unreachable("unsupported");
	}
	llvm_unreachable("covered switch");
	}

	SILLocation getLocation() const { return inst->getLoc(); }

	SILModule &getModule() const { return inst->getModule(); }
	SILFunction *getFunction() const { return inst->getFunction(); }

	DynamicCastFeasibility classifyFeasibility(bool allowWholeModule) const {
	return swift::classifyDynamicCast(
	getModule().getSwiftModule(),
	getSourceFormalType(), getTargetFormalType(),
	isSourceTypeExact(), allowWholeModule && getModule().isWholeModule());
	}

	bool isBridgingCast() const {
	// Bridging casts cannot be further simplified.
	auto TargetIsBridgeable = getTargetFormalType()->isBridgeableObjectType();
	auto SourceIsBridgeable = getSourceFormalType()->isBridgeableObjectType();
	return TargetIsBridgeable != SourceIsBridgeable;
	}

	/// Returns true if this dynamic cast can release its source operand.
	bool isRCIdentityPreserving() const;

	/// If getSourceType() is a Swift type that can bridge to an ObjC type, return
	/// the ObjC type it bridges to. If the source type is an objc type, an empty
	/// CanType() is returned.
	CanType getBridgedSourceType() const {
	SILModule &mod = getModule();
	Type t = mod.getASTContext().getBridgedToObjC(mod.getSwiftModule(),
	getSourceFormalType());
	if (!t)
	return CanType();
	return t->getCanonicalType();
	}

	/// If getTargetType() is a Swift type that can bridge to an ObjC type, return
	/// the ObjC type it bridges to. If the target type is an objc type, an empty
	/// CanType() is returned.
	CanType getBridgedTargetType() const {
	SILModule &mod = getModule();
	Type t = mod.getASTContext().getBridgedToObjC(mod.getSwiftModule(),
	getTargetFormalType());
	if (!t)
	return CanType();
	return t->getCanonicalType();
	}

	Optional<SILType> getLoweredBridgedTargetObjectType() const {
	CanType t = getBridgedTargetType();
	if (!t)
	return None;
	return SILType::getPrimitiveObjectType(t);
	}

	bool isConditional() const {
	switch (getKind()) {
	case SILDynamicCastKind::CheckedCastAddrBranchInst: {
	auto f = classifyFeasibility(true /allow wmo/);
	return f == DynamicCastFeasibility::MaySucceed;
	}
	case SILDynamicCastKind::CheckedCastBranchInst: {
	auto f = classifyFeasibility(false /allow wmo/);
	return f == DynamicCastFeasibility::MaySucceed;
	}
	case SILDynamicCastKind::CheckedCastValueBranchInst: {
	auto f = classifyFeasibility(false /allow wmo opts/);
	return f == DynamicCastFeasibility::MaySucceed;
	}
	case SILDynamicCastKind::UnconditionalCheckedCastAddrInst:
	case SILDynamicCastKind::UnconditionalCheckedCastInst:
	return false;
	case SILDynamicCastKind::UnconditionalCheckedCastValueInst:
	llvm_unreachable("unsupported");
	}
	llvm_unreachable("covered switch");
	}

	bool canUseScalarCheckedCastInstructions() const {
	return swift::canUseScalarCheckedCastInstructions(
	getModule(), getSourceFormalType(), getTargetFormalType());
	}
	};

	} // end namespace swift

	#endif