module StringMap : sig ... endval optimize_constant_fold : bool refval fexp_of_ctor :
(Value.StringMap.key * Value.value) ->
Ast_util.uannot Ast.fexpval exp_of_value : Value.value -> Ast_util.uannot Ast.expval is_too_large : Value.value -> boolval safe_primops : (Value.value list -> Value.value) StringMap.tval opt_fold_to_unit : string list refWe can specify a list of identifiers that we want to remove from the final AST here. This is useful for removing tracing features in optimized builds, e.g. for booting an OS as fast as possible.
Basically we just do this by mapping
f(x, y, z) -> ()
when f is in the list of identifiers to be mapped to unit. The advantage of doing it like this is if x, y, and z are computationally expensive then we remove them also. String concatentation is very expensive at runtime so this is something we really want when cutting out tracing features. Obviously it's important that they don't have any meaningful side effects, and that f does actually have type unit.
val fold_to_unit : Ast_util.IdSet.elt -> boolval is_constant : Type_check.tannot Ast.exp -> boolval is_constant_fexp : Type_check.tannot Ast.fexp -> boolval run : Interpreter.frame -> Value.valueThis rewriting pass looks for function applications (E_app) expressions where every argument is a literal. It passes these expressions to the OCaml interpreter in interpreter.ml, and reconstructs the values returned back into expressions which are then re-typechecked and re-inserted back into the AST.
We don't use the effect system to decide if expressions are safe to evaluate, because this ignores I/O, and would force us to ignore functions that maybe throw exceptions internally but as called are totally safe. Instead any exceptions during evaluation are caught, and the original expression is kept. Some causes of this could be:
val initial_state :
(Type_check.tannot, 'a) Ast_defs.ast ->
Type_check.Env.t ->
Interpreter.lstate * Interpreter.gstatetype fixed = {registers : Type_check.tannot Ast.exp Ast_util.Bindings.t;fields : Type_check.tannot Ast.exp Ast_util.Bindings.t Ast_util.Bindings.t;}val no_fixed : fixedval rw_exp :
fixed ->
string ->
(unit -> 'a) ->
(unit -> 'b) ->
Interpreter.state ->
Type_check.tannot Ast.exp ->
Type_check.tannot Ast.expval rewrite_exp_once :
string ->
Interpreter.state ->
Type_check.tannot Ast.exp ->
Type_check.tannot Ast.expval rewrite_constant_function_calls' :
fixed ->
string ->
(Type_check.tannot, Type_check.env) Ast_defs.ast ->
Type_check.typed_astval rewrite_constant_function_calls :
fixed ->
string ->
(Type_check.tannot, Type_check.env) Ast_defs.ast ->
Type_check.typed_asttype to_constant = | Register of Ast.id * Ast.typ * Type_check.tannot Ast.exp| Register_field of Ast.id * Ast.id * Ast.typ * Type_check.tannot Ast.exp