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open LustreSpec
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open Corelang
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open Machine_code
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let rec eliminate elim instr =
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let e_expr = eliminate_expr elim in
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match instr with
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| MLocalAssign (i,v) -> MLocalAssign (i, e_expr v)
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| MStateAssign (i,v) -> MStateAssign (i, e_expr v)
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| MReset i -> instr
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| MStep (il, i, vl) -> MStep(il, i, List.map e_expr vl)
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| MBranch (g,hl) ->
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MBranch
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(e_expr g,
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(List.map
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(fun (l, il) -> l, List.map (eliminate elim) il)
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hl
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)
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)
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and eliminate_expr elim expr =
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match expr with
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| LocalVar v -> if List.mem_assoc v elim then List.assoc v elim else expr
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| Fun (id, vl) -> Fun (id, List.map (eliminate_expr elim) vl)
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| Array(vl) -> Array(List.map (eliminate_expr elim) vl)
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| Access(v1, v2) -> Access(eliminate_expr elim v1, eliminate_expr elim v2)
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| Power(v1, v2) -> Access(eliminate_expr elim v1, eliminate_expr elim v2)
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| Cst _ | StateVar _ -> expr
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(* see if elim has to take in account the provided instr:
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if so, upodate elim and return the remove flag,
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otherwise, the expression should be kept and elim is left untouched *)
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let update_elim elim instr =
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Format.eprintf "SHOULD WE STORE THE EXPRESSION IN INSTR %a TO ELIMINATE IT@." pp_instr instr;
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let apply elim v new_e =
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(v, new_e)::List.map (fun (v, e) -> v, eliminate_expr [v, new_e] e) elim
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in
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match instr with
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(* Simple cases*)
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| MLocalAssign (v, (Cst _ as e))
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| MLocalAssign (v, (LocalVar _ as e))
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| MLocalAssign (v, (StateVar _ as e)) -> true, apply elim v e
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(* When optimization >= 3, we also inline any basic operator call.
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All those are returning a single ouput *)
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| MStep([v], id, vl) when
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List.mem id Basic_library.internal_funs
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&& !Options.optimization >= 3
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-> assert false
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(* true, apply elim v (Fun(id, vl))*)
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| MLocalAssign (v, ((Fun (id, il)) as e)) when
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List.mem id Basic_library.internal_funs (* this will avoid inlining ite *)
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&& !Options.optimization >= 3
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-> (
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Format.eprintf "WE STORE THE EXPRESSION DEFINING %s TO ELIMINATE IT@." v.var_id;
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true, apply elim v e
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)
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| _ ->
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(* default case, we keep the instruction and do not modify elim *)
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false, elim
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(** We iterate in the order, recording simple local assigns in an accumulator
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1. each expression is rewritten according to the accumulator
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2. local assigns then rewrite occurrences of the lhs in the computed accumulator
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*)
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let optimize_minstrs instrs =
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let rev_instrs, eliminate =
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List.fold_left (fun (rinstrs, elim) instr ->
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(* each subexpression in instr that could be rewritten by the elim set is
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rewritten *)
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let instr = eliminate elim instr in
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(* if instr is a simple local assign, then (a) elim is simplified with it (b) it
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is stored as the elim set *)
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let remove, elim = update_elim elim instr in
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(if remove then rinstrs else instr::rinstrs), elim
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) ([],[]) instrs
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in
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let eliminated_vars = List.map fst eliminate in
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eliminated_vars, List.rev rev_instrs
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(** Perform optimization on machine code:
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- iterate through step instructions and remove simple local assigns
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*)
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let optimize_machine machine =
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let eliminated_vars, new_instrs = optimize_minstrs machine.mstep.step_instrs in
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let new_locals =
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List.filter (fun v -> not (List.mem v eliminated_vars)) machine.mstep.step_locals
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in
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{
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machine with
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mstep = {
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machine.mstep with
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step_locals = new_locals;
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step_instrs = new_instrs
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}
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}
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let optimize_machines machines =
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List.map optimize_machine machines
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(* Local Variables: *)
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(* compile-command:"make -C .." *)
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(* End: *)
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