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class BoxUnbox[BT <: BTypes] extends AnyRef

Source
BoxUnbox.scala
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Instance Constructors

  1. new BoxUnbox(btypes: BT)

Type Members

  1. sealed trait BoxConsumer extends AnyRef
  2. sealed trait BoxCreation extends AnyRef
  3. trait BoxKind extends AnyRef
  4. class CopyOpsIterator extends Iterator[AbstractInsnNode]

    For a set of box creation operations and a corresponding set of box consumer operations, this iterator returns all copy operations (load, store, dup) that are in between.

  5. case class EscapingConsumer (consumer: AbstractInsnNode) extends BoxConsumer with Product with Serializable

    An unknown box consumer

  6. case class InstanceCreation (newOp: TypeInsnNode, dupOp: InsnNode, initCall: MethodInsnNode) extends BoxCreation with Product with Serializable
  7. case class ModuleFactory (moduleLoad: AbstractInsnNode, producer: MethodInsnNode) extends BoxCreation with Product with Serializable
  8. case class ModuleGetter (moduleLoad: AbstractInsnNode, consumer: MethodInsnNode) extends BoxConsumer with Product with Serializable

    An extractor method in a Scala module, e.g., Predef.Integer2int

  9. case class PrimitiveBox (boxedType: Type, boxClass: InternalName) extends BoxKind with Product with Serializable
  10. case class PrimitiveBoxingGetter (consumer: MethodInsnNode) extends BoxConsumer with Product with Serializable

    A getter that boxes the returned value, e.g., Tuple2$mcII$sp._1

  11. case class PrimitiveUnboxingGetter (consumer: MethodInsnNode, unboxedPrimitive: Type) extends BoxConsumer with Product with Serializable

    A getter that unboxes the returned value, e.g., Tuple2._1$mcI$sp

  12. case class Ref (boxedType: Type, refClass: InternalName) extends BoxKind with Product with Serializable
  13. case class StaticFactory (producer: MethodInsnNode, loadInitialValues: Option[List[AbstractInsnNode]]) extends BoxCreation with Product with Serializable
  14. case class StaticGetterOrInstanceRead (consumer: AbstractInsnNode) extends BoxConsumer with Product with Serializable

    Static extractor (BoxesRunTime.unboxToInt) or GETFIELD or getter invocation

  15. case class StaticSetterOrInstanceWrite (consumer: AbstractInsnNode) extends BoxConsumer with Product with Serializable

    PUTFIELD or setter invocation

  16. case class Tuple (boxedTypes: List[Type], tupleClass: InternalName) extends BoxKind with Product with Serializable

Value Members

  1. final def !=(arg0: Any): Boolean

    Test two objects for inequality.

    Test two objects for inequality.

    returns

    true if !(this == that), false otherwise.

    Definition Classes
    AnyRef → Any
  2. final def ##(): Int

    Equivalent to x.hashCode except for boxed numeric types and null.

    Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.

    returns

    a hash value consistent with ==

    Definition Classes
    AnyRef → Any
  3. def +(other: String): String
    Implicit
    This member is added by an implicit conversion from BoxUnbox[BT] to any2stringadd[BoxUnbox[BT]] performed by method any2stringadd in scala.Predef.
    Definition Classes
    any2stringadd
  4. def ->[B](y: B): (BoxUnbox[BT], B)
    Implicit
    This member is added by an implicit conversion from BoxUnbox[BT] to ArrowAssoc[BoxUnbox[BT]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  5. final def ==(arg0: Any): Boolean

    The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).

    The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).

    returns

    true if the receiver object is equivalent to the argument; false otherwise.

    Definition Classes
    AnyRef → Any
  6. def allCreationsConsumers(initialCreation: BoxCreation, boxKind: BoxKind, prodCons: ProdConsAnalyzer): Option[(Set[BoxCreation], Set[BoxConsumer])]

    Given a box creations operation

    Given a box creations operation

    • find all ultimate consumers for the produced value. then:
      • for all consumed values, find all producer operations. check that all are box creations
        • recurse until reaching a fixpoint

    Returns a set of box creations and a set of box consumers. Note that the box consumers may contain EscapingConsumers, even if there are multiple box creation operations. The callee will handle this case (and not attempt to eliminate the box).

  7. final def asInstanceOf[T0]: T0

    Cast the receiver object to be of type T0.

    Cast the receiver object to be of type T0.

    Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

    returns

    the receiver object.

    Definition Classes
    Any
    Exceptions thrown

    ClassCastException if the receiver object is not an instance of the erasure of type T0.

  8. def boxUnboxElimination(method: MethodNode, owner: InternalName): Boolean

    Eliminate box-unbox pairs within method.

    Eliminate box-unbox pairs within method. Such appear commonly after closure elimination:

    def t2 = { val f = (b: Byte, i: Int) => i + b // no specialized variant for this function type f(1, 2) // invokes the generic apply }

    The closure optimizer re-writes the apply call to anonfun$adapted method, which takes boxed arguments. After inlining this method, we get

    def t2 = { val a = boxByte(1) val b = boxInteger(2) val r = boxInteger(anonfun$(unboxByte(a), unboxInt(b))) unboxInt(r) }

    All these box/unbox operations are eliminated here.

    Implementation: for every box operation, find all consumers of the boxed value, then all producers of these consumers, repeat until reaching a fixpoint. If this results in a set of boxing and unboxing operations, the box can be eliminated.

    There are two methods for eliminating boxes: M1: If there is a single boxing operation, the boxed value(s) are stored into new local variable(s) at the allocation site. Accesses to the boxed value are re-written to reads / writes of these locals. Advantages:

    • supports mutable boxes (IntRef and friends)
    • supports eliminating unbox operations even if the box object needs to be created because it escapes (see E4)
      • works by keeping the unboxed value(s) in locals AND the box in its original form
      • only for immutable boxes: modifications to the escaped box cannot be applied to the local variable(s) holding the boxed value(s). Restriction:
    • does not work if there are multiple boxing operations (see E1)

    M2: If there are multiple boxing operations, the boxing operations are simply eliminated, leaving the unboxed value(s) on the stack. Store / load operations that previously acted on the box are adapted to handle the boxed type(s). If the box contains multiple values (or a size-2 value, which doesn't fit into locals that were used for the box), new local slots are used for store / load operations. Restrictions:

    • does not support re-writing writes to (mutable) boxes (see E2)
    • does not support re-writing reads of boxes that also escape (see E3)

    E1: M1 only works if there's a single boxing operation. def e1(b: Boolean) = { val i: Integer = box(10) // 10 is stored into a new local, box operation and i removed val j: Integer = box(20) // 20 is stored into a new local, box operation adn j removed val r = if (b) i else j // loads and stores of the box are eliminated, r no longer exists unbox(r) // cannot rewrite: we don't know which local to load } Note: the example has no write and the box does not escape, so M2 works here.

    E2: mutable boxes with multiple boxing operations cannot be eliminated. M1: see E1 M2: cannot replace an IntRef on the stack by an Int value on the stack, an Int on the stack cannot be modified.

    def e2(b: Boolean) = { val r1 = new IntRef(0) val r2 = new IntRef(1) val modRef = if (b) r1 else r2 modRef.elem += 10 // M1: cannot rewrite: which local to write? same as E1. (if (b) r1 else r2).elem += 10 // M2: cannot change an Int on the stack (r1.elem, r2.elem) }

    E3: escaping boxes with multiple boxing operations cannot be rewritten. M1: see E1. M2: at *, instead of an Integer, an Int is on the stack, but the escape method expects an Integer. We cannot just create a box at this point: if there are multiple escapes (or an escape is executed more than once), the difference could be observed (reference equality).

    def e3(b: Boolean) = { val i: Integer = box(1) val j: Integer = box(2) escape(if (b) i else j) // * unbox(if (b) i else j) }

    E4: M1 supports rewriting unbox operations of immutable boxes that escape def e4 = { val i: Integer = box(10) // 10 is stored into a new local, loaded as argument for the box call escape(i) // not changed, still loads the local i holding the box unbox(i) // rewritten to a pop (of the box) and a load of the local variable }

    E4 seems to be a bit of a corner case, but it's necessary to unblock box eliminations with mutual dependencies. Example:

    val ((a, b), c) = ((1, 2), 3) a + b + c

    generates (after a few cleanups) the following (pseudo-bytecode, ignoring primitive boxing, specialization):

    load 1, load 2, new Tuple2 // stack: Tuple2 load 3 // stack: Tuple2; Int val local1 = new Tuple2 val local2 = local1._1.asInstanceOf[Tuple2] val c = local1._2.asInstanceOf[Int] if (local2 == null) throw new MatchError(local1) val a = local2._1 val b = local2._2 a + b + c

    In order to eliminate the tuples, we first need to eliminate the outer tuple (stored in local1)

    • single box operation, so we use M1
    • there are three consumers of the outer tuple: local1._1, local1._2 and new MatchError(local1). in the last one, the tuple escapes.
    • note that the MatchError creation is dead code: local2 is never null. However, our nullness analysis cannot identify this: it does not track nullness through tuple stores and loads.
    • if we re-write the non-escaping consumers of the outer tuple, but keep the tuple allocation and the escaping consumer, we get the follwoing:

    load 1, load 2 val newLocal1 = new Tuple2; load newLocal1 // stack: Tuple2 val newLocal2 = 3; load newLocal2 // stack: Tuple2; Int val local1 = new Tuple2 val local2 = newLocal1 val c = newLocal2 if (local2 == null) throw new MatchError(local1) val a = local2._1 val b = local2._2 a + b + c

    At this point, the nullness analysis sees that local2 == null is false, dead code elimination removes the throw new MatchError(local1). After eliminating the allocation of the outer tuple, the inner tuple (stored in newLocal1) can also be eliminated.

    Special case for tuples wrt specialization: a tuple getter may box or unbox the value stored in the tuple: calling _1 on a Tuple2$mcII$sp boxes the primitive Int stored in the tuple. Similarly, calling _1$mcI$sp on a non-specialized Tuple2 unboxes the Integer in the tuple. When eliminating such getters, we have to introduce appropriate box / unbox calls.

    TODO: add new calls (box / unbox) to the call graph (not urgent) TODO: update the call graph because stack heights change (not urgent). this may also affect other optimizations, we ignored the issue so far. check how stack heights stored in the call graph are used. Note: these tasks are not urgent because the call graph is not currently used during / after method-local optimizations, only before to perform inlining and closure rewriting.

  9. val btypes: BT
  10. def checkCopyOpReplacements(initialProds: Set[BoxCreation], finalCons: Set[BoxConsumer], valueTypes: List[Type], nextLocal: Int, prodCons: ProdConsAnalyzer): Option[(Map[AbstractInsnNode, List[AbstractInsnNode]], Int, Map[Int, Type])]

    Takes two sets initialProds and finalCons such that all boxes produced by the first set are only consumed by an operation in the second set.

    Takes two sets initialProds and finalCons such that all boxes produced by the first set are only consumed by an operation in the second set.

    Returns a map that replaces copy operations (ALOAD / ASTORE) between the producers and consumers with corresponding copy operations for the values stored in the box. The returned Int value returns the next free local variable slot.

    Examples:

    • for an Integer box, an ASTORE x is simply replaced by ISTORE x
    • for a pair of two references, an ASTORE x is replaced by ASTORE x1; ASTORE x2 where x1 and x2 are fresh locals

    Not all copy operations can be supported: DUP only works for single-value boxes, the more exotic copy operations (DUP2_X2) are not supported (note that Scalac never emits them). If a copy operation cannot be replaced, this method returns None.

  11. def clone(): AnyRef

    Create a copy of the receiver object.

    Create a copy of the receiver object.

    The default implementation of the clone method is platform dependent.

    returns

    a copy of the receiver object.

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
    Note

    not specified by SLS as a member of AnyRef

  12. def ensuring(cond: (BoxUnbox[BT]) ⇒ Boolean, msg: ⇒ Any): BoxUnbox[BT]
    Implicit
    This member is added by an implicit conversion from BoxUnbox[BT] to Ensuring[BoxUnbox[BT]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  13. def ensuring(cond: (BoxUnbox[BT]) ⇒ Boolean): BoxUnbox[BT]
    Implicit
    This member is added by an implicit conversion from BoxUnbox[BT] to Ensuring[BoxUnbox[BT]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  14. def ensuring(cond: Boolean, msg: ⇒ Any): BoxUnbox[BT]
    Implicit
    This member is added by an implicit conversion from BoxUnbox[BT] to Ensuring[BoxUnbox[BT]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  15. def ensuring(cond: Boolean): BoxUnbox[BT]
    Implicit
    This member is added by an implicit conversion from BoxUnbox[BT] to Ensuring[BoxUnbox[BT]] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  16. final def eq(arg0: AnyRef): Boolean

    Tests whether the argument (that) is a reference to the receiver object (this).

    Tests whether the argument (that) is a reference to the receiver object (this).

    The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:

    • It is consistent: for any non-null instances x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false.
    • For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false.
    • null.eq(null) returns true.

    When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).

    returns

    true if the argument is a reference to the receiver object; false otherwise.

    Definition Classes
    AnyRef
  17. def equals(arg0: Any): Boolean

    The equality method for reference types.

    The equality method for reference types. Default implementation delegates to eq.

    See also equals in scala.Any.

    returns

    true if the receiver object is equivalent to the argument; false otherwise.

    Definition Classes
    AnyRef → Any
  18. def finalize(): Unit

    Called by the garbage collector on the receiver object when there are no more references to the object.

    Called by the garbage collector on the receiver object when there are no more references to the object.

    The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.

    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
    Note

    not specified by SLS as a member of AnyRef

  19. def formatted(fmtstr: String): String
    Implicit
    This member is added by an implicit conversion from BoxUnbox[BT] to StringFormat[BoxUnbox[BT]] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  20. final def getClass(): Class[_]

    Returns the runtime class representation of the object.

    Returns the runtime class representation of the object.

    returns

    a class object corresponding to the runtime type of the receiver.

    Definition Classes
    AnyRef → Any
  21. def hashCode(): Int

    The hashCode method for reference types.

    The hashCode method for reference types. See hashCode in scala.Any.

    returns

    the hash code value for this object.

    Definition Classes
    AnyRef → Any
  22. final def isInstanceOf[T0]: Boolean

    Test whether the dynamic type of the receiver object is T0.

    Test whether the dynamic type of the receiver object is T0.

    Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will return true. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

    returns

    true if the receiver object is an instance of erasure of type T0; false otherwise.

    Definition Classes
    Any
  23. final def ne(arg0: AnyRef): Boolean

    Equivalent to !(this eq that).

    Equivalent to !(this eq that).

    returns

    true if the argument is not a reference to the receiver object; false otherwise.

    Definition Classes
    AnyRef
  24. final def notify(): Unit

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Wakes up a single thread that is waiting on the receiver object's monitor.

    Definition Classes
    AnyRef
    Note

    not specified by SLS as a member of AnyRef

  25. final def notifyAll(): Unit

    Wakes up all threads that are waiting on the receiver object's monitor.

    Wakes up all threads that are waiting on the receiver object's monitor.

    Definition Classes
    AnyRef
    Note

    not specified by SLS as a member of AnyRef

  26. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  27. def toString(): String

    Creates a String representation of this object.

    Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.

    returns

    a String representation of the object.

    Definition Classes
    AnyRef → Any
  28. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  29. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  30. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  31. def →[B](y: B): (BoxUnbox[BT], B)
    Implicit
    This member is added by an implicit conversion from BoxUnbox[BT] to ArrowAssoc[BoxUnbox[BT]] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
  32. object BoxKind
  33. object PrimitiveBox extends Serializable
  34. object Ref extends Serializable
  35. object Tuple extends Serializable

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion any2stringadd from BoxUnbox[BT] to any2stringadd[BoxUnbox[BT]]

Inherited by implicit conversion StringFormat from BoxUnbox[BT] to StringFormat[BoxUnbox[BT]]

Inherited by implicit conversion Ensuring from BoxUnbox[BT] to Ensuring[BoxUnbox[BT]]

Inherited by implicit conversion ArrowAssoc from BoxUnbox[BT] to ArrowAssoc[BoxUnbox[BT]]

Ungrouped