scala.tools.nsc.backend.icode.analysis

# TypeFlowAnalysis

#### abstract class TypeFlowAnalysis extends AnyRef

A data-flow analysis on types, that works on `ICode`.

Source
  TypeFlowAnalysis.scala

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2. by StringFormat
3. by Ensuring
4. by ArrowAssoc

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### Instance Constructors

1. #### new TypeFlowAnalysis()

### Type Members

1. #### case class CallsiteInfo(bb: Global.icodes.BasicBlock, receiver: Global.Symbol, stackLength: Int, concreteMethod: Global.Symbol) extends Product with Serializable

2. #### class MTFAGrowable extends MethodTFA

   A full type-flow analysis on a method computes in- and out-flows for each basic block (that's what MethodTFA does).

   A full type-flow analysis on a method computes in- and out-flows for each basic block (that's what MethodTFA does).

   For the purposes of Inliner, doing so guarantees that an abstract typestack-slot is available by the time an inlining candidate (a CALL_METHOD instruction) is visited. This subclass (MTFAGrowable) of MethodTFA also aims at performing such analysis on CALL_METHOD instructions, with some differences:

   (a) early screening is performed while the type-flow is being computed (in an override of `blockTransfer`) by testing a subset of the conditions that Inliner checks later. The reasoning here is: if the early check fails at some iteration, there's no chance a follow-up iteration (with a yet more lub-ed typestack-slot) will succeed. Failure is sufficient to remove that particular CALL_METHOD from the typeflow's `remainingCALLs`. A forward note: in case inlining occurs at some basic block B, all blocks reachable from B get their CALL_METHOD instructions considered again as candidates (because of the more precise types that -- perhaps -- can be computed).

   (b) in case the early check does not fail, no conclusive decision can be made, thus the CALL_METHOD stays `isOnwatchlist`.

   In other words, `remainingCALLs` tracks those callsites that still remain as candidates for inlining, so that Inliner can focus on those. `remainingCALLs` also caches info about the typestack just before the callsite, so as to spare computing them again at inlining time.

   Besides caching, a further optimization involves skipping those basic blocks whose in-flow and out-flow isn't needed anyway (as explained next). A basic block lacking a callsite in `remainingCALLs`, when visisted by the standard algorithm, won't cause any inlining. But as we know from the way type-flows are computed, computing the in- and out-flow for a basic block relies in general on those of other basic blocks. In detail, we want to focus on that sub-graph of the CFG such that control flow may reach a remaining candidate callsite. Those basic blocks not in that subgraph can be skipped altogether. That's why:

   - `forwardAnalysis()` in `MTFAGrowable` now checks for inclusion of a basic block in `relevantBBs`
   - same check is performed before adding a block to the worklist, and as part of choosing successors. The bookkeeping supporting on-the-fly pruning of irrelevant blocks requires overridding most methods of the dataflow-analysis.

   The rest of the story takes place in Inliner, which does not visit all of the method's basic blocks but only on those represented in `remainingCALLs`.

3. #### class MethodTFA extends DataFlowAnalysis[typeFlowLattice.type]

4. #### class Timer extends AnyRef

5. #### class VarBinding extends HashMap[Global.icodes.Local, Global.icodes.TypeKind]

   A map which returns the bottom type for unfound elements

### Abstract Value Members

1. #### abstract val global: Global

### Concrete 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 information
     This member is added by an implicit conversion from TypeFlowAnalysis to any2stringadd[TypeFlowAnalysis] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd

4. #### def ->[B](y: B): (TypeFlowAnalysis, B)

   Implicit information
     This member is added by an implicit conversion from TypeFlowAnalysis to ArrowAssoc[TypeFlowAnalysis] 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 clone(): AnyRef

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

8. #### def ensuring(cond: (TypeFlowAnalysis) ⇒ Boolean, msg: ⇒ Any): TypeFlowAnalysis

   Implicit information
     This member is added by an implicit conversion from TypeFlowAnalysis to Ensuring[TypeFlowAnalysis] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring

9. #### def ensuring(cond: (TypeFlowAnalysis) ⇒ Boolean): TypeFlowAnalysis

   Implicit information
     This member is added by an implicit conversion from TypeFlowAnalysis to Ensuring[TypeFlowAnalysis] performed by method Ensuring in scala.Predef.
   Definition Classes
     Ensuring

10. #### def ensuring(cond: Boolean, msg: ⇒ Any): TypeFlowAnalysis

    Implicit information
      This member is added by an implicit conversion from TypeFlowAnalysis to Ensuring[TypeFlowAnalysis] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

11. #### def ensuring(cond: Boolean): TypeFlowAnalysis

    Implicit information
      This member is added by an implicit conversion from TypeFlowAnalysis to Ensuring[TypeFlowAnalysis] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring

12. #### final def eq(arg0: AnyRef): Boolean

    Definition Classes
      AnyRef

13. #### def equals(arg0: Any): Boolean

    Definition Classes
      AnyRef → Any

14. #### def finalize(): Unit

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

15. #### def formatted(fmtstr: String): String

    Implicit information
      This member is added by an implicit conversion from TypeFlowAnalysis to StringFormat[TypeFlowAnalysis] performed by method StringFormat in scala.Predef.
    Definition Classes
      StringFormat
    Annotations
      @inline()

16. #### final def getClass(): Class[_]

    Definition Classes
      AnyRef → Any

17. #### def hashCode(): Int

    Definition Classes
      AnyRef → Any

18. #### final def isInstanceOf[T0]: Boolean

    Definition Classes
      Any

19. #### final def ne(arg0: AnyRef): Boolean

    Definition Classes
      AnyRef

20. #### final def notify(): Unit

    Definition Classes
      AnyRef

21. #### final def notifyAll(): Unit

    Definition Classes
      AnyRef

22. #### final def synchronized[T0](arg0: ⇒ T0): T0

    Definition Classes
      AnyRef

23. #### val timer: Timer

24. #### def toString(): String

    Definition Classes
      AnyRef → Any

25. #### object typeFlowLattice extends SemiLattice

    The type flow lattice contains a binding from local variable names to types and a type stack.

26. #### object typeLattice extends SemiLattice

    The lattice of ICode types.

27. #### object typeStackLattice extends SemiLattice

    The lattice of type stacks.

    The lattice of type stacks. It is a straight forward extension of the type lattice (lub is pairwise lub of the list elements).

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): (TypeFlowAnalysis, B)

    Implicit information
      This member is added by an implicit conversion from TypeFlowAnalysis to ArrowAssoc[TypeFlowAnalysis] performed by method ArrowAssoc in scala.Predef.
    Definition Classes
      ArrowAssoc

### Inherited from AnyRef

### Inherited from Any

### Inherited by implicit conversion any2stringadd from TypeFlowAnalysis to any2stringadd[TypeFlowAnalysis]

### Inherited by implicit conversion StringFormat from TypeFlowAnalysis to StringFormat[TypeFlowAnalysis]

### Inherited by implicit conversion Ensuring from TypeFlowAnalysis to Ensuring[TypeFlowAnalysis]

### Inherited by implicit conversion ArrowAssoc from TypeFlowAnalysis to ArrowAssoc[TypeFlowAnalysis]

### Ungrouped