735 lines
28 KiB
OCaml
735 lines
28 KiB
OCaml
(***********************************************************************)
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(* *)
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(* Objective Caml *)
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(* *)
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(* Xavier Leroy, projet Cristal, INRIA Rocquencourt *)
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(* *)
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(* Copyright 1996 Institut National de Recherche en Informatique et *)
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(* en Automatique. All rights reserved. This file is distributed *)
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(* under the terms of the Q Public License version 1.0. *)
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(* *)
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(***********************************************************************)
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(* $Id$ *)
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(* Introduction of closures, uncurrying, recognition of direct calls *)
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open Misc
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open Asttypes
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open Primitive
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open Lambda
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open Switch
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open Clambda
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(* Auxiliaries for compiling functions *)
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let rec split_list n l =
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if n <= 0 then ([], l) else begin
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match l with
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[] -> fatal_error "Closure.split_list"
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| a::l -> let (l1, l2) = split_list (n-1) l in (a::l1, l2)
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end
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let rec build_closure_env env_param pos = function
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[] -> Tbl.empty
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| id :: rem ->
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Tbl.add id (Uprim(Pfield pos, [Uvar env_param]))
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(build_closure_env env_param (pos+1) rem)
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(* Check if a variable occurs in a [clambda] term. *)
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let occurs_var var u =
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let rec occurs = function
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Uvar v -> v = var
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| Uconst cst -> false
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| Udirect_apply(lbl, args) -> List.exists occurs args
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| Ugeneric_apply(funct, args) -> occurs funct || List.exists occurs args
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| Uclosure(fundecls, clos) -> List.exists occurs clos
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| Uoffset(u, ofs) -> occurs u
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| Ulet(id, def, body) -> occurs def || occurs body
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| Uletrec(decls, body) ->
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List.exists (fun (id, u) -> occurs u) decls || occurs body
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| Uprim(p, args) -> List.exists occurs args
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| Uswitch(arg, s) ->
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occurs arg ||
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occurs_array s.us_actions_consts || occurs_array s.us_actions_blocks
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| Ustaticfail (_, args) -> List.exists occurs args
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| Ucatch(_, _, body, hdlr) -> occurs body || occurs hdlr
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| Utrywith(body, exn, hdlr) -> occurs body || occurs hdlr
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| Uifthenelse(cond, ifso, ifnot) ->
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occurs cond || occurs ifso || occurs ifnot
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| Usequence(u1, u2) -> occurs u1 || occurs u2
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| Uwhile(cond, body) -> occurs cond || occurs body
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| Ufor(id, lo, hi, dir, body) -> occurs lo || occurs hi || occurs body
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| Uassign(id, u) -> id = var || occurs u
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| Usend(met, obj, args) ->
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occurs met || occurs obj || List.exists occurs args
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and occurs_array a =
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try
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for i = 0 to Array.length a - 1 do
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if occurs a.(i) then raise Exit
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done;
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false
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with Exit ->
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true
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in occurs u
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(* Determine whether the estimated size of a clambda term is below
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some threshold *)
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let prim_size prim args =
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match prim with
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Pidentity -> 0
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| Pgetglobal id -> 1
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| Psetglobal id -> 1
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| Pmakeblock(tag, mut) -> 5 + List.length args
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| Pfield f -> 1
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| Psetfield(f, isptr) -> if isptr then 4 else 1
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| Pfloatfield f -> 1
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| Psetfloatfield f -> 1
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| Pccall p -> (if p.prim_alloc then 10 else 4) + List.length args
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| Praise -> 4
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| Pstringlength -> 5
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| Pstringrefs | Pstringsets -> 6
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| Pmakearray kind -> 5 + List.length args
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| Parraylength kind -> if kind = Pgenarray then 6 else 2
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| Parrayrefu kind -> if kind = Pgenarray then 12 else 2
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| Parraysetu kind -> if kind = Pgenarray then 16 else 4
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| Parrayrefs kind -> if kind = Pgenarray then 18 else 8
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| Parraysets kind -> if kind = Pgenarray then 22 else 10
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| Pbittest -> 3
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| Pbigarrayref(ndims, _, _) -> 4 + ndims * 6
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| Pbigarrayset(ndims, _, _) -> 4 + ndims * 6
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| _ -> 2 (* arithmetic and comparisons *)
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(* Very raw approximation of switch cost *)
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let lambda_smaller lam threshold =
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let size = ref 0 in
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let rec lambda_size lam =
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if !size > threshold then raise Exit;
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match lam with
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Uvar v -> ()
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| Uconst(Const_base(Const_int _ | Const_char _ | Const_float _) |
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Const_pointer _) -> incr size
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| Uconst _ ->
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raise Exit (* avoid duplication of structured constants *)
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| Udirect_apply(fn, args) ->
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size := !size + 4; lambda_list_size args
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| Ugeneric_apply(fn, args) ->
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size := !size + 6; lambda_size fn; lambda_list_size args
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| Uclosure(defs, vars) ->
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raise Exit (* inlining would duplicate function definitions *)
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| Uoffset(lam, ofs) ->
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incr size; lambda_size lam
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| Ulet(id, lam, body) ->
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lambda_size lam; lambda_size body
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| Uletrec(bindings, body) ->
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raise Exit (* usually too large *)
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| Uprim(prim, args) ->
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size := !size + prim_size prim args;
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lambda_list_size args
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| Uswitch(lam, cases) ->
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if Array.length cases.us_actions_consts > 1 then size := !size + 5 ;
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if Array.length cases.us_actions_blocks > 1 then size := !size + 5 ;
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lambda_size lam;
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lambda_array_size cases.us_actions_consts ;
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lambda_array_size cases.us_actions_blocks
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| Ustaticfail (_,args) -> lambda_list_size args
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| Ucatch(_, _, body, handler) ->
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incr size; lambda_size body; lambda_size handler
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| Utrywith(body, id, handler) ->
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size := !size + 8; lambda_size body; lambda_size handler
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| Uifthenelse(cond, ifso, ifnot) ->
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size := !size + 2;
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lambda_size cond; lambda_size ifso; lambda_size ifnot
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| Usequence(lam1, lam2) ->
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lambda_size lam1; lambda_size lam2
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| Uwhile(cond, body) ->
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size := !size + 2; lambda_size cond; lambda_size body
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| Ufor(id, low, high, dir, body) ->
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size := !size + 4; lambda_size low; lambda_size high; lambda_size body
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| Uassign(id, lam) ->
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incr size; lambda_size lam
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| Usend(met, obj, args) ->
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size := !size + 8;
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lambda_size met; lambda_size obj; lambda_list_size args
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and lambda_list_size l = List.iter lambda_size l
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and lambda_array_size a = Array.iter lambda_size a in
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try
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lambda_size lam; !size <= threshold
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with Exit ->
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false
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(* Check if a clambda term is ``pure'',
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that is without side-effects *and* not containing function definitions *)
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let rec is_pure_clambda = function
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Uvar v -> true
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| Uconst cst -> true
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| Uprim((Psetglobal _ | Psetfield _ | Psetfloatfield _ |
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Pccall _ | Praise | Poffsetref _ | Pstringsetu | Pstringsets |
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Parraysetu _ | Parraysets _ | Pbigarrayset _), _) -> false
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| Uprim(p, args) -> List.for_all is_pure_clambda args
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| _ -> false
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(* Simplify primitive operations on integers *)
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let make_const_int n = (Uconst(Const_base(Const_int n)), Value_integer n)
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let make_const_ptr n = (Uconst(Const_pointer n), Value_constptr n)
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let make_const_bool b = make_const_ptr(if b then 1 else 0)
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let simplif_prim_pure p (args, approxs) =
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match approxs with
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[Value_integer x] ->
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begin match p with
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Pidentity -> make_const_int x
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| Pnegint -> make_const_int (-x)
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| Poffsetint y -> make_const_int (x + y)
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| _ -> (Uprim(p, args), Value_unknown)
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end
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| [Value_integer x; Value_integer y] ->
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begin match p with
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Paddint -> make_const_int(x + y)
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| Psubint -> make_const_int(x - y)
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| Pmulint -> make_const_int(x * y)
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| Pdivint when y <> 0 -> make_const_int(x / y)
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| Pmodint when y <> 0 -> make_const_int(x mod y)
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| Pandint -> make_const_int(x land y)
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| Porint -> make_const_int(x lor y)
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| Pxorint -> make_const_int(x lxor y)
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| Plslint -> make_const_int(x lsl y)
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| Plsrint -> make_const_int(x lsr y)
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| Pasrint -> make_const_int(x asr y)
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| Pintcomp cmp ->
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let result = match cmp with
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Ceq -> x = y
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| Cneq -> x <> y
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| Clt -> x < y
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| Cgt -> x > y
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| Cle -> x <= y
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| Cge -> x >= y in
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make_const_bool result
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| _ -> (Uprim(p, args), Value_unknown)
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end
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| [Value_constptr x] ->
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begin match p with
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Pidentity -> make_const_ptr x
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| Pnot -> make_const_bool(x = 0)
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| Pisint -> make_const_bool true
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| _ -> (Uprim(p, args), Value_unknown)
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end
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| [Value_constptr x; Value_constptr y] ->
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begin match p with
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Psequand -> make_const_bool(x <> 0 && y <> 0)
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| Psequor -> make_const_bool(x <> 0 || y <> 0)
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| _ -> (Uprim(p, args), Value_unknown)
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end
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| _ ->
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(Uprim(p, args), Value_unknown)
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let simplif_prim p (args, approxs as args_approxs) =
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if List.for_all is_pure_clambda args
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then simplif_prim_pure p args_approxs
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else (Uprim(p, args), Value_unknown)
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(* Substitute variables in a [ulambda] term (a body of an inlined function)
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and perform some more simplifications on integer primitives.
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Also perform alpha-conversion on let-bound identifiers to avoid
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clashes with locally-generated identifiers.
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The variables must not be assigned in the term.
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This is used to substitute "trivial" arguments for parameters
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during inline expansion. *)
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let approx_ulam = function
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Uconst(Const_base(Const_int n)) -> Value_integer n
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| Uconst(Const_base(Const_char c)) -> Value_integer(Char.code c)
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| Uconst(Const_pointer n) -> Value_constptr n
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| _ -> Value_unknown
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let rec substitute sb ulam =
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match ulam with
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Uvar v ->
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begin try Tbl.find v sb with Not_found -> ulam end
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| Uconst cst -> ulam
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| Udirect_apply(lbl, args) ->
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Udirect_apply(lbl, List.map (substitute sb) args)
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| Ugeneric_apply(fn, args) ->
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Ugeneric_apply(substitute sb fn, List.map (substitute sb) args)
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| Uclosure(defs, env) ->
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(* never present in an inlined function body; painful to get right *)
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assert false
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| Uoffset(u, ofs) -> Uoffset(substitute sb u, ofs)
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| Ulet(id, u1, u2) ->
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let id' = Ident.rename id in
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Ulet(id', substitute sb u1, substitute (Tbl.add id (Uvar id') sb) u2)
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| Uletrec(bindings, body) ->
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(* never present in an inlined function body; painful to get right *)
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assert false
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| Uprim(p, args) ->
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let sargs = List.map (substitute sb) args in
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let (res, _) = simplif_prim p (sargs, List.map approx_ulam sargs) in
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res
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| Uswitch(arg, sw) ->
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Uswitch(substitute sb arg,
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{ sw with
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us_actions_consts =
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Array.map (substitute sb) sw.us_actions_consts;
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us_actions_blocks =
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Array.map (substitute sb) sw.us_actions_blocks;
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})
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| Ustaticfail (nfail, args) ->
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Ustaticfail (nfail, List.map (substitute sb) args)
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| Ucatch(nfail, ids, u1, u2) ->
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Ucatch(nfail, ids, substitute sb u1, substitute sb u2)
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| Utrywith(u1, id, u2) ->
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let id' = Ident.rename id in
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Utrywith(substitute sb u1, id', substitute (Tbl.add id (Uvar id') sb) u2)
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| Uifthenelse(u1, u2, u3) ->
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begin match substitute sb u1 with
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Uconst(Const_pointer n) ->
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if n <> 0 then substitute sb u2 else substitute sb u3
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| su1 ->
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Uifthenelse(su1, substitute sb u2, substitute sb u3)
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end
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| Usequence(u1, u2) -> Usequence(substitute sb u1, substitute sb u2)
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| Uwhile(u1, u2) -> Uwhile(substitute sb u1, substitute sb u2)
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| Ufor(id, u1, u2, dir, u3) ->
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let id' = Ident.rename id in
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Ufor(id', substitute sb u1, substitute sb u2, dir,
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substitute (Tbl.add id (Uvar id') sb) u3)
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| Uassign(id, u) ->
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let id' =
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try
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match Tbl.find id sb with Uvar i -> i | _ -> assert false
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with Not_found ->
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id in
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Uassign(id', substitute sb u)
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| Usend(u1, u2, ul) ->
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Usend(substitute sb u1, substitute sb u2, List.map (substitute sb) ul)
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(* Perform an inline expansion *)
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let is_simple_argument = function
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Uvar _ -> true
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| Uconst(Const_base(Const_int _ | Const_char _ | Const_float _)) -> true
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| Uconst(Const_pointer _) -> true
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| _ -> false
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let no_effects = function
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Uclosure _ -> true
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| Uconst(Const_base(Const_string _)) -> true
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| u -> is_simple_argument u
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let rec bind_params subst params args body =
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match (params, args) with
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([], []) -> substitute subst body
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| (p1 :: pl, a1 :: al) ->
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if is_simple_argument a1 then
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bind_params (Tbl.add p1 a1 subst) pl al body
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else begin
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let p1' = Ident.rename p1 in
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let body' = bind_params (Tbl.add p1 (Uvar p1') subst) pl al body in
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if occurs_var p1 body then Ulet(p1', a1, body')
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else if no_effects a1 then body'
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else Usequence(a1, body')
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end
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| (_, _) -> assert false
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(* Check if a lambda term is ``pure'',
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that is without side-effects *and* not containing function definitions *)
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let rec is_pure = function
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Lvar v -> true
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| Lconst cst -> true
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| Lprim((Psetglobal _ | Psetfield _ | Psetfloatfield _ |
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Pccall _ | Praise | Poffsetref _ | Pstringsetu | Pstringsets |
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Parraysetu _ | Parraysets _), _) -> false
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| Lprim(p, args) -> List.for_all is_pure args
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| _ -> false
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(* Generate a direct application *)
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let direct_apply fundesc funct ufunct uargs =
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let app_args =
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if fundesc.fun_closed then uargs else uargs @ [ufunct] in
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let app =
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match fundesc.fun_inline with
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None -> Udirect_apply(fundesc.fun_label, app_args)
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| Some(params, body) -> bind_params Tbl.empty params app_args body in
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(* If ufunct can contain side-effects or function definitions,
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we must make sure that it is evaluated exactly once.
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If the function is not closed, we evaluate ufunct as part of the
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arguments.
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If the function is closed, we force the evaluation of ufunct first. *)
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if not fundesc.fun_closed || is_pure funct
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then app
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else Usequence(ufunct, app)
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(* Add [Value_integer] or [Value_constptr] info to the approximation
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of an application *)
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let strengthen_approx appl approx =
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match approx_ulam appl with
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(Value_integer _ | Value_constptr _) as intapprox -> intapprox
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| _ -> approx
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(* If a term has approximation Value_integer or Value_constptr and is pure,
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replace it by an integer constant *)
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let check_constant_result lam ulam approx =
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match approx with
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Value_integer n when is_pure lam -> make_const_int n
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| Value_constptr n when is_pure lam -> make_const_ptr n
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| _ -> (ulam, approx)
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(* Evaluate an expression with known value for its side effects only,
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or discard it if it's pure *)
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let sequence_constant_expr lam ulam1 (ulam2, approx2 as res2) =
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if is_pure lam then res2 else (Usequence(ulam1, ulam2), approx2)
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(* Maintain the approximation of the global structure being defined *)
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let global_approx = ref([||] : value_approximation array)
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(* Maintain the nesting depth for functions *)
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let function_nesting_depth = ref 0
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let excessive_function_nesting_depth = 5
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(* Uncurry an expression and explicitate closures.
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Also return the approximation of the expression.
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The approximation environment [fenv] maps idents to approximations.
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Idents not bound in [fenv] approximate to [Value_unknown].
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The closure environment [cenv] maps idents to [ulambda] terms.
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It is used to substitute environment accesses for free identifiers. *)
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let close_approx_var fenv cenv id =
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let approx = try Tbl.find id fenv with Not_found -> Value_unknown in
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match approx with
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Value_integer n ->
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make_const_int n
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| Value_constptr n ->
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make_const_ptr n
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| approx ->
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let subst = try Tbl.find id cenv with Not_found -> Uvar id in
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(subst, approx)
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let close_var fenv cenv id =
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let (ulam, app) = close_approx_var fenv cenv id in ulam
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exception Found of int
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let rec close fenv cenv = function
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Lvar id ->
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close_approx_var fenv cenv id
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| Lconst cst ->
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begin match cst with
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Const_base(Const_int n) -> (Uconst cst, Value_integer n)
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| Const_base(Const_char c) -> (Uconst cst, Value_integer(Char.code c))
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| Const_pointer n -> (Uconst cst, Value_constptr n)
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| _ -> (Uconst cst, Value_unknown)
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end
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| Lfunction(kind, params, body) as funct ->
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close_one_function fenv cenv (Ident.create "fun") funct
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| Lapply(funct, args) ->
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let nargs = List.length args in
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begin match (close fenv cenv funct, close_list fenv cenv args) with
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((ufunct, Value_closure(fundesc, approx_res)),
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[Uprim(Pmakeblock(_, _), uargs)])
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when List.length uargs = - fundesc.fun_arity ->
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let app = direct_apply fundesc funct ufunct uargs in
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(app, strengthen_approx app approx_res)
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| ((ufunct, Value_closure(fundesc, approx_res)), uargs)
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when nargs = fundesc.fun_arity ->
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let app = direct_apply fundesc funct ufunct uargs in
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(app, strengthen_approx app approx_res)
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| ((ufunct, Value_closure(fundesc, approx_res)), uargs)
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when fundesc.fun_arity > 0 && nargs > fundesc.fun_arity ->
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let (first_args, rem_args) = split_list fundesc.fun_arity uargs in
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(Ugeneric_apply(direct_apply fundesc funct ufunct first_args,
|
|
rem_args),
|
|
Value_unknown)
|
|
| ((ufunct, _), uargs) ->
|
|
(Ugeneric_apply(ufunct, uargs), Value_unknown)
|
|
end
|
|
| Lsend(met, obj, args) ->
|
|
let (umet, _) = close fenv cenv met in
|
|
let (uobj, _) = close fenv cenv obj in
|
|
(Usend(umet, uobj, close_list fenv cenv args), Value_unknown)
|
|
| Llet(str, id, lam, body) ->
|
|
let (ulam, alam) = close_named fenv cenv id lam in
|
|
begin match (str, alam) with
|
|
(Variable, _) ->
|
|
let (ubody, abody) = close fenv cenv body in
|
|
(Ulet(id, ulam, ubody), abody)
|
|
| (_, (Value_integer _ | Value_constptr _))
|
|
when str = Alias || is_pure lam ->
|
|
close (Tbl.add id alam fenv) cenv body
|
|
| (_, _) ->
|
|
let (ubody, abody) = close (Tbl.add id alam fenv) cenv body in
|
|
(Ulet(id, ulam, ubody), abody)
|
|
end
|
|
| Lletrec(defs, body) ->
|
|
if List.for_all
|
|
(function (id, Lfunction(_, _, _)) -> true | _ -> false)
|
|
defs
|
|
then begin
|
|
(* Simple case: only function definitions *)
|
|
let (clos, infos) = close_functions fenv cenv defs in
|
|
let clos_ident = Ident.create "clos" in
|
|
let fenv_body =
|
|
List.fold_right
|
|
(fun (id, pos, approx) fenv -> Tbl.add id approx fenv)
|
|
infos fenv in
|
|
let (ubody, approx) = close fenv_body cenv body in
|
|
(Ulet(clos_ident, clos,
|
|
List.fold_right
|
|
(fun (id, pos, approx) body ->
|
|
Ulet(id, Uoffset(Uvar clos_ident, pos), body))
|
|
infos ubody),
|
|
approx)
|
|
end else begin
|
|
(* General case: recursive definition of values *)
|
|
let rec clos_defs = function
|
|
[] -> ([], fenv)
|
|
| (id, lam) :: rem ->
|
|
let (udefs, fenv_body) = clos_defs rem in
|
|
let (ulam, approx) = close fenv cenv lam in
|
|
((id, ulam) :: udefs, Tbl.add id approx fenv_body) in
|
|
let (udefs, fenv_body) = clos_defs defs in
|
|
let (ubody, approx) = close fenv_body cenv body in
|
|
(Uletrec(udefs, ubody), approx)
|
|
end
|
|
| Lprim(Pgetglobal id, []) as lam ->
|
|
check_constant_result lam
|
|
(Uprim(Pgetglobal id, [])) (Compilenv.global_approx id)
|
|
| Lprim(Pmakeblock(tag, mut) as prim, lams) ->
|
|
let (ulams, approxs) = List.split (List.map (close fenv cenv) lams) in
|
|
(Uprim(prim, ulams),
|
|
begin match mut with
|
|
Immutable -> Value_tuple(Array.of_list approxs)
|
|
| Mutable -> Value_unknown
|
|
end)
|
|
| Lprim(Pfield n, [lam]) ->
|
|
let (ulam, approx) = close fenv cenv lam in
|
|
let fieldapprox =
|
|
match approx with
|
|
Value_tuple a when n < Array.length a -> a.(n)
|
|
| _ -> Value_unknown in
|
|
check_constant_result lam (Uprim(Pfield n, [ulam])) fieldapprox
|
|
| Lprim(Psetfield(n, _), [Lprim(Pgetglobal id, []); lam]) ->
|
|
let (ulam, approx) = close fenv cenv lam in
|
|
(!global_approx).(n) <- approx;
|
|
(Uprim(Psetfield(n, false), [Uprim(Pgetglobal id, []); ulam]),
|
|
Value_unknown)
|
|
| Lprim(p, args) ->
|
|
simplif_prim p (close_list_approx fenv cenv args)
|
|
| Lswitch(arg, sw) as l ->
|
|
(* NB: failaction might get copied, thus it should be some Lstaticraise *)
|
|
let (uarg, _) = close fenv cenv arg in
|
|
let const_index, const_actions =
|
|
close_switch fenv cenv sw.sw_consts sw.sw_numconsts sw.sw_failaction
|
|
and block_index, block_actions =
|
|
close_switch fenv cenv sw.sw_blocks sw.sw_numblocks sw.sw_failaction in
|
|
(Uswitch(uarg,
|
|
{us_index_consts = const_index;
|
|
us_actions_consts = const_actions;
|
|
us_index_blocks = block_index;
|
|
us_actions_blocks = block_actions}),
|
|
Value_unknown)
|
|
| Lstaticraise (i, args) ->
|
|
(Ustaticfail (i, close_list fenv cenv args), Value_unknown)
|
|
| Lstaticcatch(body, (i, vars), handler) ->
|
|
let (ubody, _) = close fenv cenv body in
|
|
let (uhandler, _) = close fenv cenv handler in
|
|
(Ucatch(i, vars, ubody, uhandler), Value_unknown)
|
|
| Ltrywith(body, id, handler) ->
|
|
let (ubody, _) = close fenv cenv body in
|
|
let (uhandler, _) = close fenv cenv handler in
|
|
(Utrywith(ubody, id, uhandler), Value_unknown)
|
|
| Lifthenelse(arg, ifso, ifnot) ->
|
|
begin match close fenv cenv arg with
|
|
(uarg, Value_constptr n) ->
|
|
sequence_constant_expr arg uarg
|
|
(close fenv cenv (if n = 0 then ifnot else ifso))
|
|
| (uarg, _ ) ->
|
|
let (uifso, _) = close fenv cenv ifso in
|
|
let (uifnot, _) = close fenv cenv ifnot in
|
|
(Uifthenelse(uarg, uifso, uifnot), Value_unknown)
|
|
end
|
|
| Lsequence(lam1, lam2) ->
|
|
let (ulam1, _) = close fenv cenv lam1 in
|
|
let (ulam2, approx) = close fenv cenv lam2 in
|
|
(Usequence(ulam1, ulam2), approx)
|
|
| Lwhile(cond, body) ->
|
|
let (ucond, _) = close fenv cenv cond in
|
|
let (ubody, _) = close fenv cenv body in
|
|
(Uwhile(ucond, ubody), Value_unknown)
|
|
| Lfor(id, lo, hi, dir, body) ->
|
|
let (ulo, _) = close fenv cenv lo in
|
|
let (uhi, _) = close fenv cenv hi in
|
|
let (ubody, _) = close fenv cenv body in
|
|
(Ufor(id, ulo, uhi, dir, ubody), Value_unknown)
|
|
| Lassign(id, lam) ->
|
|
let (ulam, _) = close fenv cenv lam in
|
|
(Uassign(id, ulam), Value_unknown)
|
|
| Levent _ | Lifused _ -> assert false
|
|
|
|
and close_list fenv cenv = function
|
|
[] -> []
|
|
| lam :: rem ->
|
|
let (ulam, _) = close fenv cenv lam in
|
|
ulam :: close_list fenv cenv rem
|
|
|
|
and close_list_approx fenv cenv = function
|
|
[] -> ([], [])
|
|
| lam :: rem ->
|
|
let (ulam, approx) = close fenv cenv lam in
|
|
let (ulams, approxs) = close_list_approx fenv cenv rem in
|
|
(ulam :: ulams, approx :: approxs)
|
|
|
|
and close_named fenv cenv id = function
|
|
Lfunction(kind, params, body) as funct ->
|
|
close_one_function fenv cenv id funct
|
|
| lam ->
|
|
close fenv cenv lam
|
|
|
|
(* Build a shared closure for a set of mutually recursive functions *)
|
|
|
|
and close_functions fenv cenv fun_defs =
|
|
(* Update and check nesting depth *)
|
|
incr function_nesting_depth;
|
|
let initially_closed =
|
|
!function_nesting_depth < excessive_function_nesting_depth in
|
|
(* Determine the free variables of the functions *)
|
|
let fv =
|
|
IdentSet.elements (free_variables (Lletrec(fun_defs, lambda_unit))) in
|
|
(* Build the function descriptors for the functions.
|
|
Initially all functions are assumed not to need their environment
|
|
parameter. *)
|
|
let uncurried_defs =
|
|
List.map
|
|
(function
|
|
(id, (Lfunction(kind, params, body) as def)) ->
|
|
let label =
|
|
Compilenv.current_unit_name() ^ "__" ^ Ident.unique_name id in
|
|
let arity = List.length params in
|
|
let fundesc =
|
|
{fun_label = label;
|
|
fun_arity = (if kind = Tupled then -arity else arity);
|
|
fun_closed = initially_closed;
|
|
fun_inline = None } in
|
|
(id, params, body, fundesc)
|
|
| (_, _) -> fatal_error "Closure.close_functions")
|
|
fun_defs in
|
|
(* Build an approximate fenv for compiling the functions *)
|
|
let fenv_rec =
|
|
List.fold_right
|
|
(fun (id, params, body, fundesc) fenv ->
|
|
Tbl.add id (Value_closure(fundesc, Value_unknown)) fenv)
|
|
uncurried_defs fenv in
|
|
(* Determine the offsets of each function's closure in the shared block *)
|
|
let env_pos = ref (-1) in
|
|
let clos_offsets =
|
|
List.map
|
|
(fun (id, params, body, fundesc) ->
|
|
let pos = !env_pos + 1 in
|
|
env_pos := !env_pos + 1 + (if fundesc.fun_arity <> 1 then 3 else 2);
|
|
pos)
|
|
uncurried_defs in
|
|
let fv_pos = !env_pos in
|
|
(* This reference will be set to false if the hypothesis that a function
|
|
does not use its environment parameter is invalidated. *)
|
|
let useless_env = ref initially_closed in
|
|
(* Translate each function definition *)
|
|
let clos_fundef (id, params, body, fundesc) env_pos =
|
|
let env_param = Ident.create "env" in
|
|
let cenv_fv =
|
|
build_closure_env env_param (fv_pos - env_pos) fv in
|
|
let cenv_body =
|
|
List.fold_right2
|
|
(fun (id, params, arity, body) pos env ->
|
|
Tbl.add id (Uoffset(Uvar env_param, pos - env_pos)) env)
|
|
uncurried_defs clos_offsets cenv_fv in
|
|
let (ubody, approx) = close fenv_rec cenv_body body in
|
|
if !useless_env && occurs_var env_param ubody then useless_env := false;
|
|
let fun_params = if !useless_env then params else params @ [env_param] in
|
|
((fundesc.fun_label, fundesc.fun_arity, fun_params, ubody),
|
|
(id, env_pos, Value_closure(fundesc, approx))) in
|
|
(* Translate all function definitions. *)
|
|
let clos_info_list =
|
|
if initially_closed then begin
|
|
let cl = List.map2 clos_fundef uncurried_defs clos_offsets in
|
|
(* If the hypothesis that the environment parameters are useless has been
|
|
invalidated, then set [fun_closed] to false in all descriptions and
|
|
recompile *)
|
|
if !useless_env then cl else begin
|
|
List.iter
|
|
(fun (id, params, body, fundesc) -> fundesc.fun_closed <- false)
|
|
uncurried_defs;
|
|
List.map2 clos_fundef uncurried_defs clos_offsets
|
|
end
|
|
end else
|
|
(* Excessive closure nesting: assume environment parameter is used *)
|
|
List.map2 clos_fundef uncurried_defs clos_offsets
|
|
in
|
|
(* Update nesting depth *)
|
|
decr function_nesting_depth;
|
|
(* Return the Uclosure node and the list of all identifiers defined,
|
|
with offsets and approximations. *)
|
|
let (clos, infos) = List.split clos_info_list in
|
|
(Uclosure(clos, List.map (close_var fenv cenv) fv), infos)
|
|
|
|
(* Same, for one non-recursive function *)
|
|
|
|
and close_one_function fenv cenv id funct =
|
|
match close_functions fenv cenv [id, funct] with
|
|
((Uclosure([_, _, params, body], _) as clos),
|
|
[_, _, (Value_closure(fundesc, _) as approx)]) ->
|
|
(* See if the function can be inlined *)
|
|
if lambda_smaller body (!Clflags.inline_threshold + List.length params)
|
|
then fundesc.fun_inline <- Some(params, body);
|
|
(clos, approx)
|
|
| _ -> fatal_error "Closure.close_one_function"
|
|
|
|
(* Close a switch *)
|
|
|
|
and close_switch fenv cenv cases num_keys default =
|
|
let index = Array.create num_keys 0
|
|
and store = mk_store Pervasives.(=) in
|
|
|
|
(* First default case *)
|
|
begin match default with
|
|
| Some def when List.length cases < num_keys ->
|
|
ignore (store.act_store def)
|
|
| _ -> ()
|
|
end ;
|
|
(* Then all other cases *)
|
|
List.iter
|
|
(fun (key,lam) ->
|
|
index.(key) <- store.act_store lam)
|
|
cases ;
|
|
(* Compile action *)
|
|
let actions =
|
|
Array.map
|
|
(fun lam ->
|
|
let ulam,_ = close fenv cenv lam in
|
|
ulam)
|
|
(store.act_get ()) in
|
|
match actions with
|
|
| [| |] -> [| |], [| |] (* May happen when default is None *)
|
|
| _ -> index, actions
|
|
|
|
|
|
(* The entry point *)
|
|
|
|
let intro size lam =
|
|
function_nesting_depth := 0;
|
|
global_approx := Array.create size Value_unknown;
|
|
Compilenv.set_global_approx(Value_tuple !global_approx);
|
|
let (ulam, approx) = close Tbl.empty Tbl.empty lam in
|
|
global_approx := [||];
|
|
ulam
|