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|
(* *********************************************************************)
(* *)
(* The Compcert verified compiler *)
(* *)
(* Xavier Leroy, INRIA Paris-Rocquencourt *)
(* *)
(* Copyright Institut National de Recherche en Informatique et en *)
(* Automatique. All rights reserved. This file is distributed *)
(* under the terms of the GNU General Public License as published by *)
(* the Free Software Foundation, either version 2 of the License, or *)
(* (at your option) any later version. This file is also distributed *)
(* under the terms of the INRIA Non-Commercial License Agreement. *)
(* *)
(* *********************************************************************)
(* Eliminate structs and unions being returned by value as function results *)
(* This is a simpler special case of [StructByValue]. *)
open C
open Cutil
open Transform
(* In function result types, struct s -> void + add 1st parameter struct s *
Try to preserve original typedef names when no change.
*)
let rec transf_type env t =
match unroll env t with
| TFun(tres, None, vararg, attr) ->
let tres' = transf_type env tres in
TFun((if is_composite_type env tres then TVoid [] else tres'),
None, vararg, attr)
| TFun(tres, Some args, vararg, attr) ->
let args' = List.map (transf_funarg env) args in
let tres' = transf_type env tres in
if is_composite_type env tres then begin
let res = Env.fresh_ident "_res" in
TFun(TVoid [], Some((res, TPtr(tres', [])) :: args'), vararg, attr)
end else
TFun(tres', Some args', vararg, attr)
| TPtr(t1, attr) ->
let t1' = transf_type env t1 in
if t1' = t1 then t else TPtr(transf_type env t1, attr)
| TArray(t1, sz, attr) ->
let t1' = transf_type env t1 in
if t1' = t1 then t else TArray(transf_type env t1, sz, attr)
| _ -> t
and transf_funarg env (id, t) = (id, transf_type env t)
(* Expressions: transform calls + rewrite the types *)
let rec transf_expr env ctx e =
let newty = transf_type env e.etyp in
match e.edesc with
| EConst c ->
{edesc = EConst c; etyp = newty}
| ESizeof ty ->
{edesc = ESizeof (transf_type env ty); etyp = newty}
| EAlignof ty ->
{edesc = EAlignof (transf_type env ty); etyp = newty}
| EVar x ->
{edesc = EVar x; etyp = newty}
| EUnop(op, e1) ->
{edesc = EUnop(op, transf_expr env Val e1); etyp = newty}
| EBinop(Oassign, lhs, {edesc = ECall(fn, args)}, ty)
when is_composite_type env ty ->
transf_composite_call env ctx (Some lhs) fn args ty
| EBinop(Ocomma, e1, e2, ty) ->
ecomma (transf_expr env Effects e1) (transf_expr env ctx e2)
| EBinop(op, e1, e2, ty) ->
{edesc = EBinop(op, transf_expr env Val e1,
transf_expr env Val e2,
transf_type env ty);
etyp = newty}
| EConditional(e1, e2, e3) ->
{edesc = EConditional(transf_expr env Val e1,
transf_expr env ctx e2,
transf_expr env ctx e3);
etyp = newty}
| ECast(ty, e1) ->
{edesc = ECast(transf_type env ty, transf_expr env Val e1); etyp = newty}
| ECall(fn, args) ->
if is_composite_type env e.etyp then
transf_composite_call env ctx None fn args e.etyp
else
{edesc = ECall(transf_expr env Val fn,
List.map (transf_expr env Val) args);
etyp = newty}
(* Function calls returning a composite: add first argument.
ctx = Effects: lv = f(...) -> f(&lv, ...) [copy optimization]
f(...) -> f(&newtemp, ...)
ctx = Val: lv = f(...) -> f(&newtemp, ...), lv = newtemp
f(...) -> f(&newtemp, ...), newtemp
*)
and transf_composite_call env ctx opt_lhs fn args ty =
let ty = transf_type env ty in
let fn = transf_expr env Val fn in
let args = List.map (transf_expr env Val) args in
match ctx, opt_lhs with
| Effects, None ->
let tmp = new_temp ~name:"_res" ty in
{edesc = ECall(fn, eaddrof tmp :: args); etyp = TVoid []}
| Effects, Some lhs ->
let lhs = transf_expr env Val lhs in
{edesc = ECall(fn, eaddrof lhs :: args); etyp = TVoid []}
| Val, None ->
let tmp = new_temp ~name:"_res" ty in
ecomma {edesc = ECall(fn, eaddrof tmp :: args); etyp = TVoid []} tmp
| Val, Some lhs ->
let lhs = transf_expr env Val lhs in
let tmp = new_temp ~name:"_res" ty in
ecomma {edesc = ECall(fn, eaddrof tmp :: args); etyp = TVoid []}
(eassign lhs tmp)
(* Initializers *)
let rec transf_init env = function
| Init_single e ->
Init_single (transf_expr env Val e)
| Init_array il ->
Init_array (List.map (transf_init env) il)
| Init_struct(id, fil) ->
Init_struct (id, List.map (fun (fld, i) -> (fld, transf_init env i)) fil)
| Init_union(id, fld, i) ->
Init_union(id, fld, transf_init env i)
(* Declarations *)
let transf_decl env (sto, id, ty, init) =
(sto, id, transf_type env ty,
match init with None -> None | Some i -> Some (transf_init env i))
(* Transformation of statements and function bodies *)
let transf_funbody env body optres =
let transf_expr ctx e = transf_expr env ctx e in
(* Function returns: if return type is struct or union,
return x -> _res = x; return
*)
let rec transf_stmt s =
match s.sdesc with
| Sskip -> s
| Sdo e ->
{s with sdesc = Sdo(transf_expr Effects e)}
| Sseq(s1, s2) ->
{s with sdesc = Sseq(transf_stmt s1, transf_stmt s2)}
| Sif(e, s1, s2) ->
{s with sdesc = Sif(transf_expr Val e,
transf_stmt s1, transf_stmt s2)}
| Swhile(e, s1) ->
{s with sdesc = Swhile(transf_expr Val e, transf_stmt s1)}
| Sdowhile(s1, e) ->
{s with sdesc = Sdowhile(transf_stmt s1, transf_expr Val e)}
| Sfor(s1, e, s2, s3) ->
{s with sdesc = Sfor(transf_stmt s1, transf_expr Val e,
transf_stmt s2, transf_stmt s3)}
| Sbreak -> s
| Scontinue -> s
| Sswitch(e, s1) ->
{s with sdesc = Sswitch(transf_expr Val e, transf_stmt s1)}
| Slabeled(lbl, s1) ->
{s with sdesc = Slabeled(lbl, transf_stmt s1)}
| Sgoto lbl -> s
| Sreturn None -> s
| Sreturn(Some e) ->
let e = transf_expr Val e in
begin match optres with
| None ->
{s with sdesc = Sreturn(Some e)}
| Some dst ->
sseq s.sloc
(sassign s.sloc dst e)
{sdesc = Sreturn None; sloc = s.sloc}
end
| Sblock sl ->
{s with sdesc = Sblock(List.map transf_stmt sl)}
| Sdecl d ->
{s with sdesc = Sdecl(transf_decl env d)}
| Sasm _ -> s
in
transf_stmt body
let transf_fundef env f =
reset_temps();
let ret = transf_type env f.fd_ret in
let params =
List.map (fun (id, ty) -> (id, transf_type env ty)) f.fd_params in
let (ret1, params1, body1) =
if is_composite_type env ret then begin
let vres = Env.fresh_ident "_res" in
let tres = TPtr(ret, []) in
let eres = {edesc = EVar vres; etyp = tres} in
let eeres = {edesc = EUnop(Oderef, eres); etyp = ret} in
(TVoid [],
(vres, tres) :: params,
transf_funbody env f.fd_body (Some eeres))
end else
(ret, params, transf_funbody env f.fd_body None) in
let temps = get_temps() in
{f with fd_ret = ret1; fd_params = params1;
fd_locals = f.fd_locals @ temps; fd_body = body1}
(* Composites *)
let transf_composite env su id attr fl =
(attr, List.map (fun f -> {f with fld_typ = transf_type env f.fld_typ}) fl)
(* Entry point *)
let program p =
Transform.program
~decl:transf_decl
~fundef:transf_fundef
~composite:transf_composite
~typedef:(fun env id ty -> transf_type env ty)
p
|
