30 lines
859 B
OCaml
30 lines
859 B
OCaml
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open Mini_c
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open Trace
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(* Overly conservative for now: ok to treat pure things as impure,
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must not treat impure things as pure. *)
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let is_pure : expression -> bool = fun e ->
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match e.content with
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| E_closure _ -> true
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| _ -> false
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let rec elim_dead_lambdas : expression -> expression result = fun e ->
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let changed = ref false in (* ugh *)
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let mapper : Helpers.mapper = fun e ->
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match e.content with
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| E_let_in ((x, _), e1, e2) when is_pure e1 ->
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let fvs = Free_variables.expression [] e2 in
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if Free_variables.mem x fvs
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then ok e
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else
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(* pure e1 is not used, eliminate! *)
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(changed := true ; ok e2)
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| _ -> ok e in
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let%bind e = Helpers.map_expression mapper e in
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if !changed
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then elim_dead_lambdas e
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else ok e
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let all_expression : expression -> expression result =
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elim_dead_lambdas
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