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|
(* Wasm_of_ocaml compiler
* http://www.ocsigen.org/js_of_ocaml/
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, with linking exception;
* either version 2.1 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*)
open Stdlib
type ctx =
{ mutable initialized : Code.Var.Set.t
; uninitialized : Code.Var.Set.t ref
}
let mark_initialized ctx i = ctx.initialized <- Code.Var.Set.add i ctx.initialized
let fork_context { initialized; uninitialized } = { initialized; uninitialized }
let check_initialized ctx i =
if not (Code.Var.Set.mem i ctx.initialized)
then ctx.uninitialized := Code.Var.Set.add i !(ctx.uninitialized)
let rec scan_expression ctx e =
match e with
| Wasm_ast.Const _ | GlobalGet _ | Pop _ | RefFunc _ | RefNull _ -> ()
| UnOp (_, e')
| I32WrapI64 e'
| I64ExtendI32 (_, e')
| F32DemoteF64 e'
| F64PromoteF32 e'
| RefI31 e'
| I31Get (_, e')
| ArrayLen e'
| StructGet (_, _, _, e')
| RefCast (_, e')
| RefTest (_, e')
| Br_on_cast (_, _, _, e')
| Br_on_cast_fail (_, _, _, e')
| Br_on_null (_, e')
| ExternConvertAny e'
| AnyConvertExtern e' -> scan_expression ctx e'
| BinOp (_, e', e'')
| ArrayNew (_, e', e'')
| ArrayNewData (_, _, e', e'')
| ArrayGet (_, _, e', e'')
| RefEq (e', e'') ->
scan_expression ctx e';
scan_expression ctx e''
| LocalGet i -> check_initialized ctx i
| LocalTee (i, e') ->
scan_expression ctx e';
mark_initialized ctx i
| Call_ref (_, e', l) ->
scan_expressions ctx l;
scan_expression ctx e'
| Call (_, l) | ArrayNewFixed (_, l) | StructNew (_, l) -> scan_expressions ctx l
| BlockExpr (_, l) -> scan_instructions ctx l
| Seq (l, e') -> scan_instructions ctx (l @ [ Push e' ])
| IfExpr (_, cond, e1, e2) ->
scan_expression ctx cond;
scan_expression (fork_context ctx) e1;
scan_expression (fork_context ctx) e2
| Try (_, body, _) -> scan_instructions ctx body
and scan_expressions ctx l = List.iter ~f:(fun e -> scan_expression ctx e) l
and scan_instruction ctx i =
match i with
| Wasm_ast.Drop e
| GlobalSet (_, e)
| Br (_, Some e)
| Br_if (_, e)
| Br_table (e, _, _)
| Throw (_, e)
| Return (Some e)
| Push e -> scan_expression ctx e
| StructSet (_, _, e, e') ->
scan_expression ctx e;
scan_expression ctx e'
| LocalSet (i, e) ->
scan_expression ctx e;
mark_initialized ctx i
| Loop (_, l) | Block (_, l) -> scan_instructions ctx l
| If (_, e, l, l') ->
scan_expression ctx e;
scan_instructions ctx l;
scan_instructions ctx l'
| CallInstr (_, l) | Return_call (_, l) -> scan_expressions ctx l
| Br (_, None) | Return None | Rethrow _ | Nop | Unreachable | Event _ -> ()
| ArraySet (_, e, e', e'') ->
scan_expression ctx e;
scan_expression ctx e';
scan_expression ctx e''
| Return_call_ref (_, e', l) ->
scan_expressions ctx l;
scan_expression ctx e'
and scan_instructions ctx l =
let ctx = fork_context ctx in
List.iter ~f:(fun i -> scan_instruction ctx i) l
let rec rewrite_expression uninitialized (e : Wasm_ast.expression) =
match e with
| Const _ | GlobalGet _ | Pop _ | RefFunc _ | RefNull _ -> e
| UnOp (op, e') -> UnOp (op, rewrite_expression uninitialized e')
| I32WrapI64 e' -> I32WrapI64 (rewrite_expression uninitialized e')
| I64ExtendI32 (s, e') -> I64ExtendI32 (s, rewrite_expression uninitialized e')
| F32DemoteF64 e' -> F32DemoteF64 (rewrite_expression uninitialized e')
| F64PromoteF32 e' -> F64PromoteF32 (rewrite_expression uninitialized e')
| RefI31 e' -> RefI31 (rewrite_expression uninitialized e')
| I31Get (s, e') -> I31Get (s, rewrite_expression uninitialized e')
| ArrayLen e' -> ArrayLen (rewrite_expression uninitialized e')
| StructGet (s, ty, i, e') -> StructGet (s, ty, i, rewrite_expression uninitialized e')
| RefCast (ty, e') -> RefCast (ty, rewrite_expression uninitialized e')
| RefTest (ty, e') -> RefTest (ty, rewrite_expression uninitialized e')
| Br_on_cast (i, ty, ty', e') ->
Br_on_cast (i, ty, ty', rewrite_expression uninitialized e')
| Br_on_cast_fail (i, ty, ty', e') ->
Br_on_cast_fail (i, ty, ty', rewrite_expression uninitialized e')
| Br_on_null (i, e') -> Br_on_null (i, rewrite_expression uninitialized e')
| BinOp (op, e', e'') ->
BinOp (op, rewrite_expression uninitialized e', rewrite_expression uninitialized e'')
| ArrayNew (ty, e', e'') ->
ArrayNew
(ty, rewrite_expression uninitialized e', rewrite_expression uninitialized e'')
| ArrayNewData (ty, i, e', e'') ->
ArrayNewData
(ty, i, rewrite_expression uninitialized e', rewrite_expression uninitialized e'')
| ArrayGet (s, ty, e', e'') ->
ArrayGet
(s, ty, rewrite_expression uninitialized e', rewrite_expression uninitialized e'')
| RefEq (e', e'') ->
RefEq (rewrite_expression uninitialized e', rewrite_expression uninitialized e'')
| LocalGet i ->
if Code.Var.Hashtbl.mem uninitialized i
then RefCast (Code.Var.Hashtbl.find uninitialized i, e)
else e
| LocalTee (i, e') ->
let e = Wasm_ast.LocalTee (i, rewrite_expression uninitialized e') in
if Code.Var.Hashtbl.mem uninitialized i
then RefCast (Code.Var.Hashtbl.find uninitialized i, e)
else e
| Call_ref (f, e', l) ->
Call_ref
(f, rewrite_expression uninitialized e', rewrite_expressions uninitialized l)
| Call (f, l) -> Call (f, rewrite_expressions uninitialized l)
| ArrayNewFixed (ty, l) -> ArrayNewFixed (ty, rewrite_expressions uninitialized l)
| StructNew (ty, l) -> StructNew (ty, rewrite_expressions uninitialized l)
| BlockExpr (ty, l) -> BlockExpr (ty, rewrite_instructions uninitialized l)
| Seq (l, e') ->
Seq (rewrite_instructions uninitialized l, rewrite_expression uninitialized e')
| IfExpr (ty, cond, e1, e2) ->
IfExpr
( ty
, rewrite_expression uninitialized cond
, rewrite_expression uninitialized e1
, rewrite_expression uninitialized e2 )
| Try (ty, body, catches) -> Try (ty, rewrite_instructions uninitialized body, catches)
| ExternConvertAny e' -> ExternConvertAny (rewrite_expression uninitialized e')
| AnyConvertExtern e' -> AnyConvertExtern (rewrite_expression uninitialized e')
and rewrite_expressions uninitialized l =
List.map ~f:(fun e -> rewrite_expression uninitialized e) l
and rewrite_instruction uninitialized i =
match i with
| Wasm_ast.Drop e -> Wasm_ast.Drop (rewrite_expression uninitialized e)
| GlobalSet (x, e) -> GlobalSet (x, rewrite_expression uninitialized e)
| Br (i, Some e) -> Br (i, Some (rewrite_expression uninitialized e))
| Br_if (i, e) -> Br_if (i, rewrite_expression uninitialized e)
| Br_table (e, l, i) -> Br_table (rewrite_expression uninitialized e, l, i)
| Throw (t, e) -> Throw (t, rewrite_expression uninitialized e)
| Return (Some e) -> Return (Some (rewrite_expression uninitialized e))
| Push e -> Push (rewrite_expression uninitialized e)
| StructSet (ty, i, e, e') ->
StructSet
(ty, i, rewrite_expression uninitialized e, rewrite_expression uninitialized e')
| LocalSet (i, e) -> LocalSet (i, rewrite_expression uninitialized e)
| Loop (ty, l) -> Loop (ty, rewrite_instructions uninitialized l)
| Block (ty, l) -> Block (ty, rewrite_instructions uninitialized l)
| If (ty, e, l, l') ->
If
( ty
, rewrite_expression uninitialized e
, rewrite_instructions uninitialized l
, rewrite_instructions uninitialized l' )
| CallInstr (f, l) -> CallInstr (f, rewrite_expressions uninitialized l)
| Return_call (f, l) -> Return_call (f, rewrite_expressions uninitialized l)
| Br (_, None) | Return None | Rethrow _ | Nop | Unreachable | Event _ -> i
| ArraySet (ty, e, e', e'') ->
ArraySet
( ty
, rewrite_expression uninitialized e
, rewrite_expression uninitialized e'
, rewrite_expression uninitialized e'' )
| Return_call_ref (f, e', l) ->
Return_call_ref
(f, rewrite_expression uninitialized e', rewrite_expressions uninitialized l)
and rewrite_instructions uninitialized l =
List.map ~f:(fun i -> rewrite_instruction uninitialized i) l
let has_default (ty : Wasm_ast.heap_type) =
match ty with
| Any | Eq | I31 -> true
| Func | Extern | Array | Struct | None_ | Type _ -> false
let f ~param_names ~locals instrs =
let ctx =
{ initialized = Code.Var.Set.empty; uninitialized = ref Code.Var.Set.empty }
in
List.iter ~f:(fun x -> mark_initialized ctx x) param_names;
List.iter
~f:(fun (var, typ) ->
match (typ : Wasm_ast.value_type) with
| I32 | I64 | F32 | F64 | Ref { nullable = true; _ } -> mark_initialized ctx var
| Ref { nullable = false; _ } -> ())
locals;
scan_instructions ctx instrs;
let local_types = Code.Var.Hashtbl.create 16 in
let locals =
List.map
~f:(fun ((var, typ) as local) ->
match typ with
| Ref ({ nullable = false; typ } as ref_typ) ->
if Code.Var.Set.mem var !(ctx.uninitialized) && not (has_default typ)
then (
Code.Var.Hashtbl.add local_types var ref_typ;
var, Wasm_ast.Ref { nullable = true; typ })
else local
| I32 | I64 | F32 | F64 | Ref { nullable = true; _ } -> local)
locals
in
let initializations =
List.filter_map
~f:(fun i ->
if Code.Var.Hashtbl.mem local_types i
then None
else Some (Wasm_ast.LocalSet (i, RefI31 (Const (I32 0l)))))
(Code.Var.Set.elements !(ctx.uninitialized))
in
let instrs =
if Code.Var.Hashtbl.length local_types = 0
then instrs
else rewrite_instructions local_types instrs
in
locals, initializations @ instrs
|
