scala.tools.nsc.backend.icode.analysis

# TypeFlowAnalysis

###
Related Doc: package analysis

#### abstract class TypeFlowAnalysis extends AnyRef

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

Source
  TypeFlowAnalysis.scala

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AnyRef, Any
Known Subclasses
analysis
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Inherited

1. TypeFlowAnalysis
2. AnyRef
3. Any

Implicitly

1. by any2stringadd
2. by StringFormat
3. by Ensuring
4. by ArrowAssoc

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Visibility

1. Public
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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 visited 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 overriding 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

   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 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

   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. #### 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`.

7. #### 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

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

    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

13. #### 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

14. #### 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

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[_]

    A representation that corresponds to the dynamic class of the receiver object.

    A representation that corresponds to the dynamic class of the receiver object.

    The nature of the representation is platform dependent.

    returns

      a representation that corresponds to the dynamic class of the receiver object.

    Definition Classes
      AnyRef → Any
    Note

      not specified by SLS as a member of AnyRef

17. #### 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

18. #### 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

19. #### 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

20. #### 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

21. #### 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

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

    Definition Classes
      AnyRef

23. #### val timer: Timer

24. #### 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

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