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:
Uncurryhas been run already, and no multiple parameter lists exit.
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Instance Constructors
- new TailCallElimination(unit: Global.CompilationUnit)
Type Members
- class ClonedTailContext extends TailContext
- class DefDefTailContext extends TailContext
- sealed trait TailContext extends AnyRef
Value Members
-
final
def
!=(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
-
final
def
##(): Int
- Definition Classes
- AnyRef → Any
-
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
-
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()
-
final
def
==(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
-
final
def
asInstanceOf[T0]: T0
- Definition Classes
- Any
-
def
atOwner[A](owner: Global.Symbol)(trans: ⇒ A): A
- Definition Classes
- Transformer
-
def
clone(): AnyRef
- Attributes
- protected[java.lang]
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
def
currentClass: Global.Symbol
- Attributes
- protected
- Definition Classes
- Transformer
-
def
currentMethod: Global.Symbol
- Attributes
- protected
- Definition Classes
- Transformer
-
var
currentOwner: Global.Symbol
- Attributes
- protected[scala]
- Definition Classes
- Transformer
-
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
-
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
-
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
-
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
-
final
def
eq(arg0: AnyRef): Boolean
- Definition Classes
- AnyRef
-
def
equals(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
-
def
finalize(): Unit
- Attributes
- protected[java.lang]
- Definition Classes
- AnyRef
- Annotations
- @throws( classOf[java.lang.Throwable] )
-
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()
-
final
def
getClass(): Class[_]
- Definition Classes
- AnyRef → Any
-
def
hashCode(): Int
- Definition Classes
- AnyRef → Any
-
final
def
isInstanceOf[T0]: Boolean
- Definition Classes
- Any
-
final
def
ne(arg0: AnyRef): Boolean
- Definition Classes
- AnyRef
- def noTailTransform(tree: Global.Tree): Global.Tree
- def noTailTransforms(trees: List[Global.Tree]): collection.immutable.List[Global.Tree]
-
final
def
notify(): Unit
- Definition Classes
- AnyRef
-
final
def
notifyAll(): Unit
- Definition Classes
- AnyRef
-
final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
- AnyRef
-
def
toString(): String
- Definition Classes
- AnyRef → Any
-
def
transform(tree: Global.Tree): Global.Tree
- Definition Classes
- TailCallElimination → Transformer
-
def
transform(tree: Global.Tree, nctx: TailContext): Global.Tree
Rewrite this tree to contain no tail recursive calls
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def
transformCaseDefs(trees: List[Global.CaseDef]): List[Global.CaseDef]
- Definition Classes
- Transformer
-
def
transformIdents(trees: List[Global.Ident]): List[Global.Ident]
- Definition Classes
- Transformer
-
def
transformMemberDefs(trees: List[Global.MemberDef]): List[Global.MemberDef]
- Definition Classes
- Transformer
-
def
transformModifiers(mods: Global.Modifiers): Global.Modifiers
- Definition Classes
- Transformer
-
def
transformStats(stats: List[Global.Tree], exprOwner: Global.Symbol): List[Global.Tree]
- Definition Classes
- Transformer
-
def
transformTemplate(tree: Global.Template): Global.Template
- Definition Classes
- Transformer
-
def
transformTrees(trees: List[Global.Tree]): List[Global.Tree]
- Definition Classes
- Transformer
-
def
transformTypeDefs(trees: List[Global.TypeDef]): List[Global.TypeDef]
- Definition Classes
- Transformer
-
def
transformUnit(unit: Global.CompilationUnit): Unit
- Definition Classes
- TailCallElimination → Transformer
-
def
transformValDef(tree: Global.ValDef): Global.ValDef
- Definition Classes
- Transformer
-
def
transformValDefs(trees: List[Global.ValDef]): List[Global.ValDef]
- Definition Classes
- Transformer
-
def
transformValDefss(treess: List[List[Global.ValDef]]): List[List[Global.ValDef]]
- Definition Classes
- Transformer
-
val
treeCopy: Global.TreeCopier
- Definition Classes
- Transformer
-
final
def
wait(): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long, arg1: Int): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
- def yesTailTransform(tree: Global.Tree): Global.Tree
-
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
- object EmptyTailContext extends TailContext
The Scala compiler API.
The following resources are useful for Scala plugin/compiler development: