Module Union.MakeSource

Create a disjoint union of two value abstractions

Parameters

Signature

Header of the abstraction

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type t = V1.t * V2.t

Type of the abstract value.

Identifier of the value domain

Sourceval accept_type : Core.All.typ -> bool

Predicate of types abstracted by the value domain

Sourceval name : string

Name of the value domain

Sourceval display : string

Display name used in debug messages

val bottom : t

Least abstract element of the lattice.

val top : t

Greatest abstract element of the lattice.

Lattice operators

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Sourceval is_bottom : t -> bool

is_bottom a tests whether a is bottom or not.

val subset : t -> t -> bool

Partial order relation. subset a1 a2 tests whether a1 is related to (or included in) a2.

val join : t -> t -> t

join a1 a2 computes an upper bound of a1 and a2.

val meet : t -> t -> t

meet a1 a2 computes a lower bound of a1 and a2.

val widen : 'a Core.All.ctx -> t -> t -> t

widen ctx a1 a2 computes an upper bound of a1 and a2 that ensures stabilization of ascending chains.

Forward semantics

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The forward semantics define how expressions are evaluated into abstract values

Forward evaluation of expressions

Sourceval avalue : 'r Core.All.avalue_kind -> t -> 'r option

Create an avalue over-approximating a given abstract value

Backward semantics

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Backward semantics define how a refinement in the abstract value of an expression impact the abstract values of the sub-expressions

Backward evaluation of expressions. backward man e ve r refines the values ve of the sub-expressions such that the evaluation of the expression e is in r i.e., we filter the sub-values ve knowing that, after applying the evaluating the expression, the result is in r

Sourceval filter : bool -> Core.All.typ -> t -> t

Keep abstract values that represent a given truth value

Sourceval compare : ('v, t) Abstraction.Value.value_man -> Core.All.operator -> bool -> Core.All.expr -> t -> Core.All.expr -> t -> t * t

Backward evaluation of boolean comparisons. compare man op true e1 v1 e2 v2 returns (v1',v2') where:

  • v1' abstracts the set of v in v1 such that v1' op v' is true for some v' in v2'
  • v2' abstracts the set of v' in v2 such that v2' op v' is true for some v in v1' i.e., we filter the abstract values v1 and v2 knowing that the test is true

Extended semantics

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Extended semantics define the evaluation of mixed-types expressions. When an expression is composed of sub-expressions with different types, several abstraction may cooperate to compute the evaluation. The previous transfer functions can't be used, because they are defined over one abstraction only.

Sourceval eval_ext : ('v, t) Abstraction.Value.value_man -> Core.All.expr -> 'v option

Extend evaluation of expressions returning the global abstract value of e. Note that the type of e may not satisfy the predicate accept_type.

Extend backward evaluation of an heterogenous expression's sub-parts

Sourceval compare_ext : ('v, t) Abstraction.Value.value_man -> Core.All.operator -> bool -> Core.All.expr -> 'v -> Core.All.expr -> 'v -> ('v * 'v) option

Extend comparison between heterogenous expressions

Communication handlers

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Sourceval ask : ('v, t) Abstraction.Value.value_man -> ('a, 'r) Core.All.query -> 'r option

Handler of queries

Pretty printer

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Sourceval print : Core.All.printer -> t -> unit

Printer of an abstract element.