Packages

c

scala.tools.nsc.transform.TailCalls

TailCallElimination

class TailCallElimination extends Global.Transformer

A Tail Call Transformer

Source
TailCalls.scala
Version

1.1 What it does: Finds method calls in tail-position and replaces them with jumps. A call is in a tail-position if it is the last instruction to be executed in the body of a method. This is done by recursing over the trees that may contain calls in tail-position (trees that can't contain such calls are not transformed). However, they are not that many. Self-recursive calls in tail-position are replaced by jumps to a label at the beginning of the method. As the JVM provides no way to jump from a method to another one, non-recursive calls in tail-position are not optimized. A method call is self-recursive if it calls the current method and the method is final (otherwise, it could be a call to an overridden method in a subclass). Furthermore, If the method has type parameters, the call must contain these parameters as type arguments. Recursive calls on a different instance are optimized. Since 'this' is not a local variable, a dummy local val is added and used as a label parameter. The backend knows to load the corresponding argument in the 'this' (local at index 0). This dummy local is never used and should be cleaned up by dead code elimination (when enabled). This phase has been moved before pattern matching to catch more of the common cases of tail recursive functions. This means that more cases should be taken into account (like nested function, and pattern cases). If a method contains self-recursive calls, a label is added to at the beginning of its body and the calls are replaced by jumps to that label. Assumes: Uncurry has been run already, and no multiple parameter lists exist.

Linear Supertypes
Global.Transformer, Global.Transformer, AnyRef, Any
Type Hierarchy
Ordering
  1. Alphabetic
  2. By Inheritance
Inherited
  1. TailCallElimination
  2. Transformer
  3. Transformer
  4. AnyRef
  5. Any
Implicitly
  1. by any2stringadd
  2. by StringFormat
  3. by Ensuring
  4. by ArrowAssoc
  1. Hide All
  2. Show All
Visibility
  1. Public
  2. All

Instance Constructors

  1. new TailCallElimination(unit: Global.CompilationUnit)

Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. def +(other: String): String
    Implicit
    This member is added by an implicit conversion from TailCallElimination to any2stringadd[TailCallElimination] performed by method any2stringadd in scala.Predef.
    Definition Classes
    any2stringadd
  4. def ->[B](y: B): (TailCallElimination, B)
    Implicit
    This member is added by an implicit conversion from TailCallElimination to ArrowAssoc[TailCallElimination] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
    Annotations
    @inline()
  5. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  6. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  7. def atOwner[A](owner: Global.Symbol)(trans: ⇒ A): A
    Definition Classes
    Transformer
  8. def clone(): AnyRef
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  9. def currentClass: Global.Symbol
    Attributes
    protected
    Definition Classes
    Transformer
  10. def currentMethod: Global.Symbol
    Attributes
    protected
    Definition Classes
    Transformer
  11. var currentOwner: Global.Symbol
    Attributes
    protected[scala]
    Definition Classes
    Transformer
  12. def ensuring(cond: (TailCallElimination) ⇒ Boolean, msg: ⇒ Any): TailCallElimination
    Implicit
    This member is added by an implicit conversion from TailCallElimination to Ensuring[TailCallElimination] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  13. def ensuring(cond: (TailCallElimination) ⇒ Boolean): TailCallElimination
    Implicit
    This member is added by an implicit conversion from TailCallElimination to Ensuring[TailCallElimination] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  14. def ensuring(cond: Boolean, msg: ⇒ Any): TailCallElimination
    Implicit
    This member is added by an implicit conversion from TailCallElimination to Ensuring[TailCallElimination] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  15. def ensuring(cond: Boolean): TailCallElimination
    Implicit
    This member is added by an implicit conversion from TailCallElimination to Ensuring[TailCallElimination] performed by method Ensuring in scala.Predef.
    Definition Classes
    Ensuring
  16. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  17. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  18. def finalize(): Unit
    Attributes
    protected[java.lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  19. def formatted(fmtstr: String): String
    Implicit
    This member is added by an implicit conversion from TailCallElimination to StringFormat[TailCallElimination] performed by method StringFormat in scala.Predef.
    Definition Classes
    StringFormat
    Annotations
    @inline()
  20. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
  21. def hashCode(): Int
    Definition Classes
    AnyRef → Any
  22. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  23. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  24. def noTailTransform(tree: Global.Tree): Global.Tree
  25. def noTailTransforms(trees: List[Global.Tree]): collection.immutable.List[Global.Tree]
  26. final def notify(): Unit
    Definition Classes
    AnyRef
  27. final def notifyAll(): Unit
    Definition Classes
    AnyRef
  28. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  29. def toString(): String
    Definition Classes
    AnyRef → Any
  30. def transform(tree: Global.Tree): Global.Tree
    Definition Classes
    TailCallElimination → Transformer
  31. def transform(tree: Global.Tree, nctx: TailContext): Global.Tree

    Rewrite this tree to contain no tail recursive calls

  32. def transformCaseDefs(trees: List[Global.CaseDef]): List[Global.CaseDef]
    Definition Classes
    Transformer
  33. def transformIdents(trees: List[Global.Ident]): List[Global.Ident]
    Definition Classes
    Transformer
  34. def transformMemberDefs(trees: List[Global.MemberDef]): List[Global.MemberDef]
    Definition Classes
    Transformer
  35. def transformModifiers(mods: Global.Modifiers): Global.Modifiers
    Definition Classes
    Transformer
  36. def transformStats(stats: List[Global.Tree], exprOwner: Global.Symbol): List[Global.Tree]
    Definition Classes
    Transformer
  37. def transformTemplate(tree: Global.Template): Global.Template
    Definition Classes
    Transformer
  38. def transformTrees(trees: List[Global.Tree]): List[Global.Tree]
    Definition Classes
    Transformer
  39. def transformTypeDefs(trees: List[Global.TypeDef]): List[Global.TypeDef]
    Definition Classes
    Transformer
  40. def transformUnit(unit: Global.CompilationUnit): Unit
    Definition Classes
    TailCallElimination → Transformer
  41. def transformValDef(tree: Global.ValDef): Global.ValDef
    Definition Classes
    Transformer
  42. def transformValDefs(trees: List[Global.ValDef]): List[Global.ValDef]
    Definition Classes
    Transformer
  43. def transformValDefss(treess: List[List[Global.ValDef]]): List[List[Global.ValDef]]
    Definition Classes
    Transformer
  44. val treeCopy: Global.TreeCopier
    Definition Classes
    Transformer
  45. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  46. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  47. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  48. def yesTailTransform(tree: Global.Tree): Global.Tree
  49. def →[B](y: B): (TailCallElimination, B)
    Implicit
    This member is added by an implicit conversion from TailCallElimination to ArrowAssoc[TailCallElimination] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
    ArrowAssoc
  50. object EmptyTailContext extends TailContext

Inherited from Global.Transformer

Inherited from Global.Transformer

Inherited from AnyRef

Inherited from Any

Inherited by implicit conversion any2stringadd from TailCallElimination to any2stringadd[TailCallElimination]

Inherited by implicit conversion StringFormat from TailCallElimination to StringFormat[TailCallElimination]

Inherited by implicit conversion Ensuring from TailCallElimination to Ensuring[TailCallElimination]

Inherited by implicit conversion ArrowAssoc from TailCallElimination to ArrowAssoc[TailCallElimination]

Ungrouped