Commit 82701aca authored by Andrei Paskevich's avatar Andrei Paskevich

Mlw: the unaffected regions do not have to be singletons

parent d9c23cbe
......@@ -654,11 +654,12 @@ let e_let ld e =
let e_exec ({c_cty = cty} as c) = match cty.cty_args with
| _::_ as al ->
(* unlike for RLpv or RLls, we do not purify the signature,
so the regions are now frozen and we have to forbid all
effects, including allocation/reset *)
check_effects cty; check_state cty;
(* no need to check eff_covers since we are completely pure *)
if List.exists (fun a -> not a.pv_ity.ity_imm) al ||
not cty.cty_result.ity_imm then Loc.errorm "This function \
has mutable type signature, it cannot be used as pure";
if not (Sreg.is_empty cty.cty_effect.eff_resets) then Loc.errorm
"This function has side effects, it cannot be used as pure";
let func a ity = ity_func a.pv_ity ity in
let ity = List.fold_right func al cty.cty_result in
let ghost = List.exists (fun a -> a.pv_ghost) al in
......@@ -1045,15 +1045,20 @@ let eff_union_seq e1 e2 =
(* NOTE: do not export this function *)
let eff_inst sbs e =
(* all modified or reset regions in e must be instantiated into
(* All modified or reset regions in e must be instantiated into
distinct regions. We allow regions that are not affected directly
to be aliased, even if they contain modified or reset subregions:
the values are still updated at the same program points and with
the same postconditions, as in the initial verified code. *)
let inst src = Mreg.fold (fun r v acc ->
let t = reg_full_inst sbs r in match t.ity_node with
| Ityreg r -> Mreg.add_new (IllegalAlias r) r v acc
| _ -> raise (IllegalSnapshot t)) src Mreg.empty in
the same postconditions, as in the initial verified code.
Every modified or reset region must be instantiated into a region,
not a snapshot. Also, every region containing a modified or reset
region, must also be instantiated into a region and not a snapshot.
The latter is not necessary for soundness, but simplifies VCgen. *)
let inst src = Mreg.fold (fun p v acc -> Mreg.fold (fun q t acc ->
match t.ity_node with
| Ityapp _ when reg_r_reachable p q -> raise (IllegalSnapshot t)
| Ityreg r when reg_equal p q -> Mreg.add_new (IllegalAlias r) r v acc
| _ -> acc) sbs.isb_reg acc) src Mreg.empty in
let writes = inst e.eff_writes in
let resets = inst e.eff_resets in
let taints = inst e.eff_taints in
......@@ -1069,7 +1074,7 @@ let eff_inst sbs e =
let sreg = Mreg.set_diff sreg e.eff_resets in
let dst = Mreg.fold (fun _ i s -> match i.ity_node with
| Ityreg r -> Sreg.add r s | _ -> s) sreg Sreg.empty in
let dst = Mtv.fold (fun _ i s -> ity_freeregs s i) sbs.isb_var dst in
let dst = Mtv.fold (fun _ i s -> ity_rch_regs s i) sbs.isb_var dst in
ignore (Mreg.inter (fun r _ _ -> raise (IllegalAlias r)) dst impact);
{ e with eff_writes = writes; eff_taints = taints;
eff_covers = covers; eff_resets = resets }
......@@ -219,6 +219,7 @@ let close_module uc =
store_module m;
let count_regions {muc_known = kn} {pv_ity = ity} mr =
let add_reg r mr = Mreg.change (fun n -> Some (n <> None)) r mr in
let meet mr1 mr2 = Mreg.union (fun _ x y -> Some (x || y)) mr1 mr2 in
......@@ -242,6 +243,7 @@ let count_regions {muc_known = kn} {pv_ity = ity} mr =
meet mr (List.fold_left add_field Mreg.empty c.rs_cty.cty_args))
Mreg.empty d.itd_constructors) in
down mr ity
let add_symbol add id v uc =
store_path uc [] id;
......@@ -257,16 +259,7 @@ let add_pdecl_no_logic uc d =
muc_known = known_add_decl uc.muc_known d;
muc_local = Sid.union uc.muc_local d.pd_news } in
let add_rs uc s = add_symbol add_ps s.rs_name (RS s) uc in
let add_rs_noalias uc s = match s.rs_logic with
| RLls _ | RLlemma ->
let sv = s.rs_cty.cty_effect.eff_reads in
let mr = Spv.fold (count_regions uc) sv Mreg.empty in
Mreg.iter (fun _ n ->
if n then Loc.errorm ?loc:s.rs_name.id_loc
"The type of this function contains an alias") mr;
add_rs uc s
| _ -> add_rs uc s in
let add_rd uc d = add_rs_noalias uc d.rec_sym in
let add_rd uc d = add_rs uc d.rec_sym in
match d.pd_node with
| PDtype tdl ->
let add uc d =
......@@ -275,7 +268,7 @@ let add_pdecl_no_logic uc d =
add_symbol add_ts d.itd_its.its_ts.ts_name d.itd_its uc in
List.fold_left add uc tdl
| PDlet (LDvar (v,_)) -> add_symbol add_ps v.pv_vs.vs_name (PV v) uc
| PDlet (LDsym (s,_)) -> add_rs_noalias uc s
| PDlet (LDsym (s,_)) -> add_rs uc s
| PDlet (LDrec l) -> List.fold_left add_rd uc l
| PDexn xs -> add_symbol add_xs xs.xs_name xs uc
| PDpure -> uc
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