[wasm] Option to implement OCaml strings with JavaScript strings

.github/workflows/build-wasm_of_ocaml.yml

@@ -75,7 +75,7 @@ jobs:
       - name: Set-up Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: latest
+          node-version: 'v24.0.0-v8-canary202412116884e26428'
 
       - name: Set-up OCaml ${{ matrix.ocaml-compiler }}
         uses: ocaml/setup-ocaml@v3

compiler/bin-wasm_of_ocaml/compile.ml

@@ -81,6 +81,35 @@ let with_runtime_files ~runtime_wasm_files f =
   in
   Wat_preprocess.with_preprocessed_files ~variables:[] ~inputs f
 
+let build_runtime ~runtime_file =
+  (* Keep this variables in sync with gen/gen.ml *)
+  let variables = [ "use-js-string", Config.Flag.use_js_string () ] in
+  match
+    List.find_opt Runtime_files.precompiled_runtimes ~f:(fun (flags, _) ->
+        assert (
+          List.length flags = List.length variables
+          && List.for_all2 ~f:(fun (k, _) (k', _) -> String.equal k k') flags variables);
+        Poly.equal flags variables)
+  with
+  | Some (_, contents) -> Fs.write_file ~name:runtime_file ~contents
+  | None ->
+      let inputs =
+        List.map
+          ~f:(fun (module_name, contents) ->
+            { Wat_preprocess.module_name
+            ; file = module_name ^ ".wat"
+            ; source = Contents contents
+            })
+          Runtime_files.wat_files
+      in
+      Runtime.build
+        ~link_options:[ "-g" ]
+        ~opt_options:[ "-g"; "-O2" ]
+        ~variables:
+          (List.map ~f:(fun (k, v) : (_ * Wat_preprocess.value) -> k, Bool v) variables)
+        ~inputs
+        ~output_file:runtime_file
+
 let link_and_optimize
     ~profile
     ~sourcemap_root
@@ -99,7 +128,7 @@ let link_and_optimize
   let enable_source_maps = Option.is_some opt_sourcemap_file in
   Fs.with_intermediate_file (Filename.temp_file "runtime" ".wasm")
   @@ fun runtime_file ->
-  Fs.write_file ~name:runtime_file ~contents:Runtime_files.wasm_runtime;
+  build_runtime ~runtime_file;
   Fs.with_intermediate_file (Filename.temp_file "wasm-merged" ".wasm")
   @@ fun temp_file ->
   opt_with
@@ -145,7 +174,7 @@ let link_and_optimize
 
 let link_runtime ~profile runtime_wasm_files output_file =
   if List.is_empty runtime_wasm_files
-  then Fs.write_file ~name:output_file ~contents:Runtime_files.wasm_runtime
+  then build_runtime ~runtime_file:output_file
   else
     Fs.with_intermediate_file (Filename.temp_file "extra_runtime" ".wasm")
     @@ fun extra_runtime ->
@@ -167,7 +196,7 @@ let link_runtime ~profile runtime_wasm_files output_file =
       ();
     Fs.with_intermediate_file (Filename.temp_file "runtime" ".wasm")
     @@ fun runtime_file ->
-    Fs.write_file ~name:runtime_file ~contents:Runtime_files.wasm_runtime;
+    build_runtime ~runtime_file;
     Binaryen.link
       ~opt_output_sourcemap:None
       ~inputs:
@@ -191,25 +220,25 @@ let generate_prelude ~out_file =
   in
   let context = Generate.start () in
   let debug = Parse_bytecode.Debug.create ~include_cmis:false false in
-  let _ =
+  let _, generated_js =
     Generate.f
       ~context
-      ~unit_name:(Some "prelude")
+      ~unit_name:(Some "wasmoo_prelude")
       ~live_vars:variable_uses
       ~in_cps
       ~deadcode_sentinal
       ~debug
       program
   in
   Generate.output ch ~context;
-  uinfo.provides
+  uinfo.provides, generated_js
 
 let build_prelude z =
   Fs.with_intermediate_file (Filename.temp_file "prelude" ".wasm")
   @@ fun prelude_file ->
   Fs.with_intermediate_file (Filename.temp_file "prelude_file" ".wasm")
   @@ fun tmp_prelude_file ->
-  let predefined_exceptions = generate_prelude ~out_file:prelude_file in
+  let info = generate_prelude ~out_file:prelude_file in
   Binaryen.optimize
     ~profile:(Driver.profile 1)
     ~input_file:prelude_file
@@ -218,7 +247,7 @@ let build_prelude z =
     ~opt_output_sourcemap:None
     ();
   Zip.add_file z ~name:"prelude.wasm" ~file:tmp_prelude_file;
-  predefined_exceptions
+  info
 
 let build_js_runtime ~primitives ?runtime_arguments () =
   let always_required_js, primitives =
@@ -396,12 +425,18 @@ let run
      let z = Zip.open_out tmp_output_file in
      Zip.add_file z ~name:"runtime.wasm" ~file:tmp_wasm_file;
      Zip.add_entry z ~name:"runtime.js" ~contents:js_runtime;
-     let predefined_exceptions = build_prelude z in
+     let predefined_exceptions, (strings, fragments) = build_prelude z in
      Link.add_info
        z
        ~predefined_exceptions
        ~build_info:(Build_info.create `Runtime)
-       ~unit_data:[]
+       ~unit_data:
+         [ { Link.unit_name = "wasmoo_prelude"
+           ; unit_info = Unit_info.empty
+           ; strings
+           ; fragments
+           }
+         ]
        ();
      Zip.close_out z)
    else

compiler/bin-wasm_of_ocaml/dune

@@ -25,9 +25,10 @@
  (target runtime_files.ml)
  (deps
   gen/gen.exe
-  ../../runtime/wasm/runtime.wasm
   ../../runtime/wasm/runtime.js
-  ../../runtime/wasm/deps.json)
+  ../../runtime/wasm/deps.json
+  (glob_files ../../runtime/wasm/*.wat)
+  (glob_files ../../runtime/wasm/runtime-*.wasm))
  (action
   (with-stdout-to
    %{target}

compiler/bin-wasm_of_ocaml/gen/gen.ml

@@ -1,13 +1,61 @@
 let read_file ic = really_input_string ic (in_channel_length ic)
 
+(* Keep the two variables below in sync with function build_runtime in
+   ../compile.ml *)
+
+let default_flags = []
+
+let interesting_runtimes = [ [ "use-js-string", false ]; [ "use-js-string", true ] ]
+
+let name_runtime l =
+  let flags = List.filter_map (fun (k, v) -> if v then Some k else None) l in
+  String.concat "-" ("runtime" :: (if flags = [] then [ "standard" ] else flags))
+  ^ ".wasm"
+
+let print_flags f flags =
+  Format.fprintf
+    f
+    "@[<2>[ %a ]@]"
+    (Format.pp_print_list
+       ~pp_sep:(fun f () -> Format.fprintf f ";@ ")
+       (fun f (k, v) ->
+         Format.fprintf f "@[\"%s\",@ %s@]" k (if v then "true" else "false")))
+    flags
+
 let () =
   let () = set_binary_mode_out stdout true in
   Format.printf
-    "let wasm_runtime = \"%s\"@."
+    "let js_runtime = \"%s\"@."
     (String.escaped (read_file (open_in_bin Sys.argv.(1))));
   Format.printf
-    "let js_runtime = \"%s\"@."
+    "let dependencies = \"%s\"@."
     (String.escaped (read_file (open_in_bin Sys.argv.(2))));
+  let wat_files, runtimes =
+    List.partition
+      (fun f -> Filename.check_suffix f ".wat")
+      (Array.to_list (Array.sub Sys.argv 3 (Array.length Sys.argv - 3)))
+  in
   Format.printf
-    "let dependencies = \"%s\"@."
-    (String.escaped (read_file (open_in_bin Sys.argv.(3))))
+    "let wat_files = [%a]@."
+    (Format.pp_print_list (fun f file ->
+         Format.fprintf
+           f
+           "\"%s\", \"%s\"; "
+           Filename.(chop_suffix (basename file) ".wat")
+           (String.escaped (read_file (open_in_bin file)))))
+    wat_files;
+  Format.printf
+    "let precompiled_runtimes = [%a]@."
+    (Format.pp_print_list (fun f flags ->
+         let flags = flags @ default_flags in
+         let name = name_runtime flags in
+         match List.find_opt (fun file -> Filename.basename file = name) runtimes with
+         | None -> failwith ("Missing runtime " ^ name)
+         | Some file ->
+             Format.fprintf
+               f
+               "%a, \"%s\"; "
+               print_flags
+               flags
+               (String.escaped (read_file (open_in_bin file)))))
+    interesting_runtimes

compiler/lib-wasm/code_generation.ml

@@ -453,7 +453,8 @@ let rec is_smi e =
   | RefNull _
   | Br_on_cast _
   | Br_on_cast_fail _
-  | Try _ -> false
+  | Try _
+  | ExternConvertAny _ -> false
   | BinOp ((F32 _ | F64 _), _, _) | RefTest _ | RefEq _ -> true
   | IfExpr (_, _, ift, iff) -> is_smi ift && is_smi iff