lib/SILGen/RValue.h - third_party/swift - Git at Google

 //===--- RValue.h - Exploded RValue Representation --------------*- C++ -*-===//
 //
 // This source file is part of the Swift.org open source project
 //
 // Copyright (c) 2014 - 2018 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
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 ///
 /// A storage structure for holding a destructured rvalue with an optional
 /// cleanup(s).
 ///
 /// Ownership of the rvalue can be "forwarded" to disable the associated
 /// cleanup(s).
 ///
 //===----------------------------------------------------------------------===//

 #ifndef SWIFT_LOWERING_RVALUE_H
 #define SWIFT_LOWERING_RVALUE_H

 #include "ManagedValue.h"
 #include "swift/Basic/NullablePtr.h"
 #include "llvm/ADT/SmallVector.h"

 namespace swift {
 namespace Lowering {

 class ArgumentSource;
 class Initialization;
 class Scope;
 class SILGenFunction;
 class TypeLowering;
 class CleanupCloner;

 /// An "exploded" SIL rvalue, in which tuple values are recursively
 /// destructured.
 ///
 /// In terms of implementation, an RValue is a collection of ManagedValues that
 /// the RValue class allows to be worked with as if they were one tuple. This
 /// allows for tuples to represent tuples without needing to canonicalize into
 /// the actual tuple value.
 ///
 /// Once constructed, RValues obey the following invariants:
 ///
 ///   1. All non-trivially typed sub-ManagedValues must consistently have
 ///   cleanups. This is verified upon construction of an RValue.
 ///
 ///   2. All sub-ManagedValues with non-trivial ValueOwnershipKind must have the
 ///   same ValueOwnershipKind. There is a subtle thing occuring here. Since all
 ///   addresses are viewed from an ownership perspective as having trivial
 ///   ownership, this causes the verification to ignore address only
 ///   values. Once we transition to opaque values, the verification will
 ///   proceed.
 ///
 ///   3. All loadable sub-ManagedValues of an RValue must be of object
 ///   type. This means that if the lowered type of an RValue is loadable, then
 ///   the RValue's sub-parts must also be objects (i.e. not
 ///   addresses). Originally this was a hard invariant of RValue constructors,
 ///   but some parts of ArgEmission pass in addresses for loadable values. So
 ///   RValue loads them in the constructor.
 ///
 ///  FIXME(opaque_values): Update invariant #2 once address only types are no
 ///  longer emitted by SILGen.
 ///
 /// *NOTE* In SILGen we don't try to explode structs, because doing so would
 /// require considering resilience, a job we want to delegate to IRGen.
 class RValue {
   friend class swift::Lowering::Scope;
   friend class swift::Lowering::ArgumentSource;
   friend class swift::Lowering::CleanupCloner;

   std::vector<ManagedValue> values;
   CanType type;
   unsigned elementsToBeAdded;

   /// Flag value used to mark an rvalue as invalid.
   ///
   /// The reasons why this can be true is:
   ///
   /// 1. The RValue was consumed.
   /// 2. The RValue was default-initialized.
   /// 3. The RValue was emitted into an SGFContext initialization.
   enum : unsigned {
     Null = ~0U,
     Used = Null - 1,
     InContext = Used - 1,
   };

   bool isInSpecialState() const {
     return elementsToBeAdded >= InContext;
   }

   // Don't copy.
   RValue(const RValue &) = delete;
   RValue &operator=(const RValue &) = delete;

   void makeUsed() {
     elementsToBeAdded = Used;
     values = {};
   }

   /// Private constructor used by copy() and borrow().
   RValue(SILGenFunction &SGF, std::vector<ManagedValue> &&values, CanType type,
          unsigned elementsToBeAdded)
       : values(std::move(values)), type(type),
         elementsToBeAdded(elementsToBeAdded) {
     verify(SGF);
   }

   /// Private constructor for RValue::extractElement and pre-exploded element
   /// constructor.
   ///
   /// If SGF is nullptr, this constructor assumes that it is passed a
   /// pre-exploded set of ManagedValues that have already been verified as being
   /// RValue compatible since they once made up an RValue. If SGF is non-null,
   /// then we verify as well that all objects of loadable type are actually
   /// loaded (i.e. are objects).
   ///
   /// *NOTE* This constructor assumes that the constructed RValue is fully
   /// formed and thus has elementsToBeAdded set to zero.
   RValue(SILGenFunction *SGF, ArrayRef<ManagedValue> values, CanType type);

   RValue(unsigned state) : elementsToBeAdded(state) {
     assert(isInSpecialState());
   }

 public:
   RValue() : elementsToBeAdded(Null) {}

   RValue(RValue &&rv) : values(std::move(rv.values)),
                         type(rv.type),
                         elementsToBeAdded(rv.elementsToBeAdded) {
     assert((rv.isComplete() || rv.isInSpecialState())
            && "moving rvalue that wasn't complete?!");
     rv.elementsToBeAdded = Used;
   }

   RValue &operator=(RValue &&rv) {
     assert((isNull() || isUsed()) && "reassigning an valid rvalue?!");

     assert((rv.isComplete() || rv.isInSpecialState())
            && "moving rvalue that wasn't complete?!");
     values = std::move(rv.values);
     type = rv.type;
     elementsToBeAdded = rv.elementsToBeAdded;
     rv.elementsToBeAdded = Used;
     return *this;
   }

   /// Create an RValue from a single value. If the value is of tuple type, it
   /// will be exploded.
   ///
   /// \param expr - the expression which yielded this r-value; its type
   ///   will become the substituted formal type of this r-value
   RValue(SILGenFunction &SGF, Expr *expr, ManagedValue v);

   /// Create an RValue from a single value. If the value is of tuple type, it
   /// will be exploded.
   RValue(SILGenFunction &SGF, SILLocation l, CanType type, ManagedValue v);

   /// Create a complete RValue from a pre-exploded set of elements.
   ///
   /// Since the RValue is assumed to be complete, no further values can be
   /// added.
   RValue(SILGenFunction &SGF, ArrayRef<ManagedValue> values, CanType type)
       : RValue(&SGF, values, type) {}

   /// Creates an invalid RValue object, in an "in-context" state.
   static RValue forInContext() {
     return RValue(InContext);
   }

   static unsigned getRValueSize(CanType substType);
   static unsigned getRValueSize(AbstractionPattern origType, CanType substType);

   /// Create an RValue to which values will be subsequently added using
   /// addElement(), with the level of tuple expansion in the input specified
   /// by the abstraction pattern. The RValue will not be complete until all
   /// the elements have been added.
   explicit RValue(AbstractionPattern pattern, CanType type);

   /// Create an RValue to which values will be subsequently added using
   /// addElement(). The RValue will not be complete until all the elements have
   /// been added.
   explicit RValue(CanType type);

   /// Return true if the rvalue was null-initialized. The intention is so one
   /// can trampoline RValue results using if statements, i.e.:
   ///
   /// if (RValue rv = foo()) {
   ///   return rv;
   /// }
   operator bool() const & { return isComplete() || isInContext(); }

   /// True if the rvalue has been completely initialized by adding all its
   /// elements.
   bool isComplete() const & { return elementsToBeAdded == 0; }

   /// True if the rvalue was null-initialized.
   bool isNull() const & { return elementsToBeAdded == Null; }

   /// True if this rvalue has been used.
   bool isUsed() const & { return elementsToBeAdded == Used; }

   /// True if this rvalue was emitted into context.
   bool isInContext() const & { return elementsToBeAdded == InContext; }

   /// Add an element to the rvalue. The rvalue must not yet be complete.
   void addElement(RValue &&element) &;

   /// Add a ManagedValue element to the rvalue, exploding tuples if necessary.
   /// The rvalue must not yet be complete.
   void addElement(SILGenFunction &SGF, ManagedValue element,
                   CanType formalType, SILLocation l) &;

   /// Forward an rvalue into a single value, imploding tuples if necessary.
   SILValue forwardAsSingleValue(SILGenFunction &SGF, SILLocation l) &&;

   /// Forward an rvalue into a single value, imploding tuples if necessary, and
   /// introducing a potential conversion from semantic type to storage type.
   SILValue forwardAsSingleStorageValue(SILGenFunction &SGF,
                                        SILType storageType,
                                        SILLocation l) &&;

   /// Get the rvalue as a single value, imploding tuples if necessary.
   ManagedValue getAsSingleValue(SILGenFunction &SGF, SILLocation l) &&;

   /// Get the rvalue as a single unmanaged value, imploding tuples if necessary.
   /// The values must not require any cleanups.
   SILValue getUnmanagedSingleValue(SILGenFunction &SGF, SILLocation l) const &;

   ManagedValue getScalarValue() && {
     assert(!isa<TupleType>(type) && "getScalarValue of a tuple rvalue");
     assert(values.size() == 1);
     auto value = values[0];
     makeUsed();
     return value;
   }

   /// Returns true if this is an rvalue that can be used safely as a +1 rvalue.
   ///
   /// This returns true iff:
   ///
   /// 1. All sub-values are trivially typed.
   /// 2. There exists at least one non-trivial typed sub-value and all such
   /// sub-values all have cleanups.
   ///
   /// *NOTE* Due to 1. isPlusOne and isPlusZero both return true for rvalues
   /// consisting of only trivial values.
   bool isPlusOne(SILGenFunction &SGF) const &;

   /// Returns true if this is an rvalue that can be used safely as a +0 rvalue.
   ///
   /// Specifically, we return true if:
   ///
   /// 1. All sub-values are trivially typed.
   /// 2. At least 1 subvalue is non-trivial and all such non-trivial values do
   /// not have a cleanup.
   ///
   /// *NOTE* Due to 1. isPlusOne and isPlusZero both return true for rvalues
   /// consisting of only trivial values.
   bool isPlusZero(SILGenFunction &SGF) const &;

   /// Use this rvalue to initialize an Initialization.
   void forwardInto(SILGenFunction &SGF, SILLocation loc, Initialization *I) &&;

   /// Copy this rvalue to initialize an Initialization without consuming the
   /// rvalue.
   void copyInto(SILGenFunction &SGF, SILLocation loc, Initialization *I) const&;

   /// Assign this r-value into the destination.
   void assignInto(SILGenFunction &SGF, SILLocation loc, SILValue destAddr) &&;

   /// Forward the exploded SILValues into a SmallVector.
   void forwardAll(SILGenFunction &SGF,
                   SmallVectorImpl<SILValue> &values) &&;

   ManagedValue materialize(SILGenFunction &SGF, SILLocation loc) &&;

   /// Take the ManagedValues from this RValue into a SmallVector.
   void getAll(SmallVectorImpl<ManagedValue> &values) &&;

   /// Store the unmanaged SILValues into a SmallVector. The values must not
   /// require any cleanups.
   void getAllUnmanaged(SmallVectorImpl<SILValue> &values) const &;

   /// Extract a single tuple element from the rvalue.
   RValue extractElement(unsigned element) &&;

   /// Extract the tuple elements from the rvalue.
   void extractElements(SmallVectorImpl<RValue> &elements) &&;

   CanType getType() const & { return type; }

   /// Return the lowered type associated with the given CanType's type lowering.
   SILType getLoweredType(SILGenFunction &SGF) const &;

   /// Return the type lowering of RValue::getType().
   const Lowering::TypeLowering &getTypeLowering(SILGenFunction &SGF) const &;

   /// Return the lowered SILType that would be used to implode the given RValue
   /// into 1 tuple value.
   ///
   /// This means that if any sub-objects are address only, an address type will
   /// be returned. Otherwise, an object will be returned. So this is a
   /// convenient way to determine if an RValue needs an address.
   SILType getLoweredImplodedTupleType(SILGenFunction &SGF) const &;

   /// Emit an equivalent value with independent ownership.
   RValue copy(SILGenFunction &SGF, SILLocation loc) const &;

   /// If this RValue is a +0 value, copy the RValue and return. Otherwise,
   /// return std::move(*this);
   RValue ensurePlusOne(SILGenFunction &SGF, SILLocation loc) &&;

   /// Borrow all subvalues of the rvalue.
   RValue borrow(SILGenFunction &SGF, SILLocation loc) const &;

   RValue copyForDiagnostics() const;

   static bool areObviouslySameValue(SILValue lhs, SILValue rhs);
   bool isObviouslyEqual(const RValue &rhs) const;

   void dump() const;
   void dump(raw_ostream &OS, unsigned indent = 0) const;

   /// Verify RValue invariants.
   ///
   /// This checks ownership invariants and also checks that all sub managed
   /// values that are loadable are actually objects.
   ///
   /// *NOTE* This is a no-op in non-assert builds.
   void verify(SILGenFunction &SGF) const &;
 };

 } // end namespace Lowering
 } // end namespace swift

 #endif
	//===--- RValue.h - Exploded RValue Representation --------------- C++ --===//
	//
	// This source file is part of the Swift.org open source project
	//
	// Copyright (c) 2014 - 2018 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
	//
	//===----------------------------------------------------------------------===//
	///
	/// \file
	///
	/// A storage structure for holding a destructured rvalue with an optional
	/// cleanup(s).
	///
	/// Ownership of the rvalue can be "forwarded" to disable the associated
	/// cleanup(s).
	///
	//===----------------------------------------------------------------------===//

	#ifndef SWIFT_LOWERING_RVALUE_H
	#define SWIFT_LOWERING_RVALUE_H

	#include "ManagedValue.h"
	#include "swift/Basic/NullablePtr.h"
	#include "llvm/ADT/SmallVector.h"

	namespace swift {
	namespace Lowering {

	class ArgumentSource;
	class Initialization;
	class Scope;
	class SILGenFunction;
	class TypeLowering;
	class CleanupCloner;

	/// An "exploded" SIL rvalue, in which tuple values are recursively
	/// destructured.
	///
	/// In terms of implementation, an RValue is a collection of ManagedValues that
	/// the RValue class allows to be worked with as if they were one tuple. This
	/// allows for tuples to represent tuples without needing to canonicalize into
	/// the actual tuple value.
	///
	/// Once constructed, RValues obey the following invariants:
	///
	/// 1. All non-trivially typed sub-ManagedValues must consistently have
	/// cleanups. This is verified upon construction of an RValue.
	///
	/// 2. All sub-ManagedValues with non-trivial ValueOwnershipKind must have the
	/// same ValueOwnershipKind. There is a subtle thing occuring here. Since all
	/// addresses are viewed from an ownership perspective as having trivial
	/// ownership, this causes the verification to ignore address only
	/// values. Once we transition to opaque values, the verification will
	/// proceed.
	///
	/// 3. All loadable sub-ManagedValues of an RValue must be of object
	/// type. This means that if the lowered type of an RValue is loadable, then
	/// the RValue's sub-parts must also be objects (i.e. not
	/// addresses). Originally this was a hard invariant of RValue constructors,
	/// but some parts of ArgEmission pass in addresses for loadable values. So
	/// RValue loads them in the constructor.
	///
	/// FIXME(opaque_values): Update invariant #2 once address only types are no
	/// longer emitted by SILGen.
	///
	/// NOTE In SILGen we don't try to explode structs, because doing so would
	/// require considering resilience, a job we want to delegate to IRGen.
	class RValue {
	friend class swift::Lowering::Scope;
	friend class swift::Lowering::ArgumentSource;
	friend class swift::Lowering::CleanupCloner;

	std::vector<ManagedValue> values;
	CanType type;
	unsigned elementsToBeAdded;

	/// Flag value used to mark an rvalue as invalid.
	///
	/// The reasons why this can be true is:
	///
	/// 1. The RValue was consumed.
	/// 2. The RValue was default-initialized.
	/// 3. The RValue was emitted into an SGFContext initialization.
	enum : unsigned {
	Null = ~0U,
	Used = Null - 1,
	InContext = Used - 1,
	};

	bool isInSpecialState() const {
	return elementsToBeAdded >= InContext;
	}

	// Don't copy.
	RValue(const RValue &) = delete;
	RValue &operator=(const RValue &) = delete;

	void makeUsed() {
	elementsToBeAdded = Used;
	values = {};
	}

	/// Private constructor used by copy() and borrow().
	RValue(SILGenFunction &SGF, std::vector<ManagedValue> &&values, CanType type,
	unsigned elementsToBeAdded)
	: values(std::move(values)), type(type),
	elementsToBeAdded(elementsToBeAdded) {
	verify(SGF);
	}

	/// Private constructor for RValue::extractElement and pre-exploded element
	/// constructor.
	///
	/// If SGF is nullptr, this constructor assumes that it is passed a
	/// pre-exploded set of ManagedValues that have already been verified as being
	/// RValue compatible since they once made up an RValue. If SGF is non-null,
	/// then we verify as well that all objects of loadable type are actually
	/// loaded (i.e. are objects).
	///
	/// NOTE This constructor assumes that the constructed RValue is fully
	/// formed and thus has elementsToBeAdded set to zero.
	RValue(SILGenFunction *SGF, ArrayRef<ManagedValue> values, CanType type);

	RValue(unsigned state) : elementsToBeAdded(state) {
	assert(isInSpecialState());
	}

	public:
	RValue() : elementsToBeAdded(Null) {}

	RValue(RValue &&rv) : values(std::move(rv.values)),
	type(rv.type),
	elementsToBeAdded(rv.elementsToBeAdded) {
	assert((rv.isComplete() \|\| rv.isInSpecialState())
	&& "moving rvalue that wasn't complete?!");
	rv.elementsToBeAdded = Used;
	}

	RValue &operator=(RValue &&rv) {
	assert((isNull() \|\| isUsed()) && "reassigning an valid rvalue?!");

	assert((rv.isComplete() \|\| rv.isInSpecialState())
	&& "moving rvalue that wasn't complete?!");
	values = std::move(rv.values);
	type = rv.type;
	elementsToBeAdded = rv.elementsToBeAdded;
	rv.elementsToBeAdded = Used;
	return *this;
	}

	/// Create an RValue from a single value. If the value is of tuple type, it
	/// will be exploded.
	///
	/// \param expr - the expression which yielded this r-value; its type
	/// will become the substituted formal type of this r-value
	RValue(SILGenFunction &SGF, Expr *expr, ManagedValue v);

	/// Create an RValue from a single value. If the value is of tuple type, it
	/// will be exploded.
	RValue(SILGenFunction &SGF, SILLocation l, CanType type, ManagedValue v);

	/// Create a complete RValue from a pre-exploded set of elements.
	///
	/// Since the RValue is assumed to be complete, no further values can be
	/// added.
	RValue(SILGenFunction &SGF, ArrayRef<ManagedValue> values, CanType type)
	: RValue(&SGF, values, type) {}

	/// Creates an invalid RValue object, in an "in-context" state.
	static RValue forInContext() {
	return RValue(InContext);
	}

	static unsigned getRValueSize(CanType substType);
	static unsigned getRValueSize(AbstractionPattern origType, CanType substType);

	/// Create an RValue to which values will be subsequently added using
	/// addElement(), with the level of tuple expansion in the input specified
	/// by the abstraction pattern. The RValue will not be complete until all
	/// the elements have been added.
	explicit RValue(AbstractionPattern pattern, CanType type);

	/// Create an RValue to which values will be subsequently added using
	/// addElement(). The RValue will not be complete until all the elements have
	/// been added.
	explicit RValue(CanType type);

	/// Return true if the rvalue was null-initialized. The intention is so one
	/// can trampoline RValue results using if statements, i.e.:
	///
	/// if (RValue rv = foo()) {
	/// return rv;
	/// }
	operator bool() const & { return isComplete() \|\| isInContext(); }

	/// True if the rvalue has been completely initialized by adding all its
	/// elements.
	bool isComplete() const & { return elementsToBeAdded == 0; }

	/// True if the rvalue was null-initialized.
	bool isNull() const & { return elementsToBeAdded == Null; }

	/// True if this rvalue has been used.
	bool isUsed() const & { return elementsToBeAdded == Used; }

	/// True if this rvalue was emitted into context.
	bool isInContext() const & { return elementsToBeAdded == InContext; }

	/// Add an element to the rvalue. The rvalue must not yet be complete.
	void addElement(RValue &&element) &;

	/// Add a ManagedValue element to the rvalue, exploding tuples if necessary.
	/// The rvalue must not yet be complete.
	void addElement(SILGenFunction &SGF, ManagedValue element,
	CanType formalType, SILLocation l) &;

	/// Forward an rvalue into a single value, imploding tuples if necessary.
	SILValue forwardAsSingleValue(SILGenFunction &SGF, SILLocation l) &&;

	/// Forward an rvalue into a single value, imploding tuples if necessary, and
	/// introducing a potential conversion from semantic type to storage type.
	SILValue forwardAsSingleStorageValue(SILGenFunction &SGF,
	SILType storageType,
	SILLocation l) &&;

	/// Get the rvalue as a single value, imploding tuples if necessary.
	ManagedValue getAsSingleValue(SILGenFunction &SGF, SILLocation l) &&;

	/// Get the rvalue as a single unmanaged value, imploding tuples if necessary.
	/// The values must not require any cleanups.
	SILValue getUnmanagedSingleValue(SILGenFunction &SGF, SILLocation l) const &;

	ManagedValue getScalarValue() && {
	assert(!isa<TupleType>(type) && "getScalarValue of a tuple rvalue");
	assert(values.size() == 1);
	auto value = values[0];
	makeUsed();
	return value;
	}

	/// Returns true if this is an rvalue that can be used safely as a +1 rvalue.
	///
	/// This returns true iff:
	///
	/// 1. All sub-values are trivially typed.
	/// 2. There exists at least one non-trivial typed sub-value and all such
	/// sub-values all have cleanups.
	///
	/// NOTE Due to 1. isPlusOne and isPlusZero both return true for rvalues
	/// consisting of only trivial values.
	bool isPlusOne(SILGenFunction &SGF) const &;

	/// Returns true if this is an rvalue that can be used safely as a +0 rvalue.
	///
	/// Specifically, we return true if:
	///
	/// 1. All sub-values are trivially typed.
	/// 2. At least 1 subvalue is non-trivial and all such non-trivial values do
	/// not have a cleanup.
	///
	/// NOTE Due to 1. isPlusOne and isPlusZero both return true for rvalues
	/// consisting of only trivial values.
	bool isPlusZero(SILGenFunction &SGF) const &;

	/// Use this rvalue to initialize an Initialization.
	void forwardInto(SILGenFunction &SGF, SILLocation loc, Initialization *I) &&;

	/// Copy this rvalue to initialize an Initialization without consuming the
	/// rvalue.
	void copyInto(SILGenFunction &SGF, SILLocation loc, Initialization *I) const&;

	/// Assign this r-value into the destination.
	void assignInto(SILGenFunction &SGF, SILLocation loc, SILValue destAddr) &&;

	/// Forward the exploded SILValues into a SmallVector.
	void forwardAll(SILGenFunction &SGF,
	SmallVectorImpl<SILValue> &values) &&;

	ManagedValue materialize(SILGenFunction &SGF, SILLocation loc) &&;

	/// Take the ManagedValues from this RValue into a SmallVector.
	void getAll(SmallVectorImpl<ManagedValue> &values) &&;

	/// Store the unmanaged SILValues into a SmallVector. The values must not
	/// require any cleanups.
	void getAllUnmanaged(SmallVectorImpl<SILValue> &values) const &;

	/// Extract a single tuple element from the rvalue.
	RValue extractElement(unsigned element) &&;

	/// Extract the tuple elements from the rvalue.
	void extractElements(SmallVectorImpl<RValue> &elements) &&;

	CanType getType() const & { return type; }

	/// Return the lowered type associated with the given CanType's type lowering.
	SILType getLoweredType(SILGenFunction &SGF) const &;

	/// Return the type lowering of RValue::getType().
	const Lowering::TypeLowering &getTypeLowering(SILGenFunction &SGF) const &;

	/// Return the lowered SILType that would be used to implode the given RValue
	/// into 1 tuple value.
	///
	/// This means that if any sub-objects are address only, an address type will
	/// be returned. Otherwise, an object will be returned. So this is a
	/// convenient way to determine if an RValue needs an address.
	SILType getLoweredImplodedTupleType(SILGenFunction &SGF) const &;

	/// Emit an equivalent value with independent ownership.
	RValue copy(SILGenFunction &SGF, SILLocation loc) const &;

	/// If this RValue is a +0 value, copy the RValue and return. Otherwise,
	/// return std::move(*this);
	RValue ensurePlusOne(SILGenFunction &SGF, SILLocation loc) &&;

	/// Borrow all subvalues of the rvalue.
	RValue borrow(SILGenFunction &SGF, SILLocation loc) const &;

	RValue copyForDiagnostics() const;

	static bool areObviouslySameValue(SILValue lhs, SILValue rhs);
	bool isObviouslyEqual(const RValue &rhs) const;

	void dump() const;
	void dump(raw_ostream &OS, unsigned indent = 0) const;

	/// Verify RValue invariants.
	///
	/// This checks ownership invariants and also checks that all sub managed
	/// values that are loadable are actually objects.
	///
	/// NOTE This is a no-op in non-assert builds.
	void verify(SILGenFunction &SGF) const &;
	};

	} // end namespace Lowering
	} // end namespace swift

	#endif