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Frama-C API - LogicSemantics

Compiler for ACSL expressions

module M : Model

Underlying memory model

type loc = M.loc
type nonrec value = M.loc value
type nonrec logic = M.loc logic
type nonrec region = M.loc region
type nonrec result = M.loc result
type sigma = M.Sigma.t

Frames

Frames are compilation environment for ACSL. A frame typically manages the current function, formal paramters, the memory environments at different labels and the \result and \exit_status values.

The frame also holds the gamma environment responsible for accumulating typing constraints, and the pool for generating fresh logic variables.

Notice that a frame is not responsible for holding the environment at label Here, since this is managed by a specific compilation environment, see env below.

type frame
val pp_frame : Stdlib.Format.formatter -> frame -> unit
val get_frame : unit -> frame

Get the current frame, or raise a fatal error if none.

val in_frame : frame -> ('a -> 'b) -> 'a -> 'b

Execute the given closure with the specified current frame. The Lang.gamma and Lang.pool contexts are also set accordingly.

val mem_at_frame : frame -> Clabels.c_label -> sigma

Get the memory environment at the given label. A fresh environment is created lazily if required. The label must not be Here.

val set_at_frame : frame -> Clabels.c_label -> sigma -> unit

Update a frame with a specific environment for the given label.

val has_at_frame : frame -> Clabels.c_label -> bool

Chek if a frame already has a specific envioronement for the given label.

val mem_frame : Clabels.c_label -> sigma

Same as mem_at_frame but for the current frame.

val mk_frame : ?kf:Frama_c_kernel.Cil_types.kernel_function -> ?result:result -> ?status:Lang.F.var -> ?formals:value Frama_c_kernel.Cil_datatype.Varinfo.Map.t -> ?labels:sigma Wp__.Clabels.LabelMap.t -> ?descr:string -> unit -> frame

Full featured constructor for frames, with fresh pool and gamma.

val local : descr:string -> frame

Make a local frame reusing the current pool and gamma.

Make a fresh frame with the given function.

type call

Internal call data.

val call : ?result:M.loc -> Frama_c_kernel.Cil_types.kernel_function -> value list -> call

Create call data from the callee point of view, deriving data (gamma and pools) from the current frame. If result is specified, the called function will stored its result at the provided location in the current frame (the callee).

val call_pre : sigma -> call -> sigma -> frame

Derive a frame from the call data suitable for compiling the called function contracts in the provided pre-state.

val call_post : sigma -> call -> sigma sequence -> frame

Derive a frame from the call data suitable for compiling the called function contracts in the provided pre-state and post-state.

val return : unit -> Frama_c_kernel.Cil_types.typ

Result type of the current function in the current frame.

val result : unit -> result

Result location of the current function in the current frame.

val status : unit -> Lang.F.var

Exit status for the current frame.

val guards : frame -> Lang.F.pred list

Returns the current gamma environment from the current frame.

Compilation Environment

type env

Compilation environment for terms and predicates. Manages the current memory state and the memory state at Here.

Remark: don't confuse the current memory state with the memory state at label Here. The current memory state is the one we have at hand when compiling a term or a predicate. Hence, inside \at(e,L) the current memory state when compiling e is the one at L.

val mk_env : ?here:sigma -> ?lvars:Frama_c_kernel.Cil_types.logic_var list -> unit -> env

Create a new environment.

Current and Here memory points are initialized to ~here, if provided.

The logic variables stand for formal parameters of ACSL logic function and ACSL predicates.

val current : env -> sigma

The current memory state. Must be propertly initialized with a specific move before.

val move_at : env -> sigma -> env

Move the compilation environment to the specified Here memory state. This memory state becomes also the new current one.

val mem_at : env -> Clabels.c_label -> sigma

Returns the memory state at the requested label. Uses the local environment for Here and the current frame otherwize.

val env_at : env -> Clabels.c_label -> env

Returns a new environment where the current memory state is moved to to the corresponding label. Suitable for compiling e inside \at(e,L) ACSL construct.

Compilers

Compile a term l-value into a (typed) abstract location

Compile a term expression.

Compile a predicate. The polarity is used to generate a weaker or stronger predicate in case of unsupported feature from WP or the underlying memory model.

Compile a predicate call.

Compile a term representing a set of memory locations into an abstract region.

val assigned_of_lval : env -> Frama_c_kernel.Cil_types.lval -> region

Computes the region assigned by a list of froms.

val assigned_of_froms : env -> Frama_c_kernel.Cil_types.from list -> region

Computes the region assigned by a list of froms.

val assigned_of_assigns : env -> Frama_c_kernel.Cil_types.assigns -> region option

Computes the region assigned by an assigns clause. None means everyhting is assigned.

Same as term above but reject any set of locations.

val loc_of_term : env -> Frama_c_kernel.Cil_types.term -> loc

Same as term above but expects a single loc or a single pointer value.

Compile a lemma definition.

Regions

val vars : region -> Lang.F.Vars.t

Qed variables appearing in a region expression.

val occurs : Lang.F.var -> region -> bool

Member of vars.

val check_assigns : unfold:int -> sigma -> written:region -> assignable:region -> Lang.F.pred

Check assigns inclusion. Compute a formula that checks whether written locations are either invalid (at the given memory location) or included in some assignable region. When ~unfold:n && n <> 0, compound memory locations are expanded field-by-field and arrays, cell-by-cell (by quantification). Up to n levels are unfolded, -1 means unlimited.