No longer call wasm-opt with --opt 1

compiler/bin-wasm_of_ocaml/compile.ml

@@ -150,77 +150,104 @@ let link_and_optimize
     | Some _ | None -> opt_sourcemap
   in
   let enable_source_maps = Option.is_some opt_sourcemap_file in
+  let run_dce = not dynlink in
+  let run_opt =
+    match (profile : Profile.t) with
+    | O1 -> false
+    | O2 | O3 -> true
+  in
+  (* [with_step_output ~is_last base] invokes its continuation with the
+     output file and sourcemap to pass to a Binaryen pass. If [is_last] the
+     pass writes directly to the final location; otherwise a pair of temp
+     files scoped to the continuation is used. *)
+  let with_step_output ~is_last base k =
+    if is_last
+    then k ~file:output_file ~opt_sm:opt_sourcemap_file
+    else
+      Fs.with_intermediate_file (Filename.temp_file base ".wasm")
+      @@ fun file ->
+      opt_with
+        Fs.with_intermediate_file
+        (if enable_source_maps then Some (Filename.temp_file base ".wasm.map") else None)
+      @@ fun opt_sm -> k ~file ~opt_sm
+  in
   Fs.with_intermediate_file (Filename.temp_file "runtime" ".wasm")
   @@ fun runtime_file ->
   build_runtime ~runtime_file;
-  Fs.with_intermediate_file (Filename.temp_file "wasm-merged" ".wasm")
-  @@ fun temp_file ->
-  opt_with
-    Fs.with_intermediate_file
-    (if enable_source_maps
-     then Some (Filename.temp_file "wasm-merged" ".wasm.map")
-     else None)
-  @@ fun opt_temp_sourcemap ->
-  (with_runtime_files ~runtime_wasm_files
-  @@ fun runtime_inputs ->
-  let t = Timer.make ~get_time:Unix.time () in
-  Binaryen.link
-    ~inputs:
-      ({ Binaryen.module_name = "env"; file = runtime_file; source_map_file = None }
-       :: runtime_inputs
-      @ List.map
-          ~f:(fun (file, source_map_file) ->
-            { Binaryen.module_name = "OCaml"; file; source_map_file })
-          wat_files)
-    ~opt_output_sourcemap:opt_temp_sourcemap
-    ~output_file:temp_file
-    ();
-  if binaryen_times () then Format.eprintf "  binaryen link: %a@." Timer.print t);
-
-  let optimize_and_finish ~opt_input_sourcemap ~input_file primitives =
+  let link ~output_file ~opt_output_sourcemap =
+    with_runtime_files ~runtime_wasm_files
+    @@ fun runtime_inputs ->
+    let t = Timer.make ~get_time:Unix.time () in
+    Binaryen.link
+      ~inputs:
+        ({ Binaryen.module_name = "env"; file = runtime_file; source_map_file = None }
+         :: runtime_inputs
+        @ List.map
+            ~f:(fun (file, source_map_file) ->
+              { Binaryen.module_name = "OCaml"; file; source_map_file })
+            wat_files)
+      ~opt_output_sourcemap
+      ~output_file
+      ();
+    if binaryen_times () then Format.eprintf "  binaryen link: %a@." Timer.print t
+  in
+  let dce ~input_file ~opt_input_sourcemap ~output_file ~opt_output_sourcemap =
+    let t = Timer.make ~get_time:Unix.time () in
+    let primitives =
+      Binaryen.dead_code_elimination
+        ~dependencies:Runtime_files.dependencies
+        ~opt_input_sourcemap
+        ~opt_output_sourcemap
+        ~input_file
+        ~output_file
+    in
+    if binaryen_times () then Format.eprintf "  binaryen dce: %a@." Timer.print t;
+    primitives
+  in
+  let optimize ~input_file ~opt_input_sourcemap =
     let t = Timer.make ~get_time:Unix.time () in
     Binaryen.optimize
       ~profile
       ~opt_input_sourcemap
-      ~opt_output_sourcemap:opt_sourcemap
+      ~opt_output_sourcemap:opt_sourcemap_file
       ~input_file
       ~output_file
       ();
-    if binaryen_times () then Format.eprintf "  binaryen opt: %a@." Timer.print t;
+    if binaryen_times () then Format.eprintf "  binaryen opt: %a@." Timer.print t
+  in
+  let finish primitives =
     Option.iter
       ~f:(update_sourcemap ~sourcemap_root ~sourcemap_don't_inline_content)
       opt_sourcemap_file;
     primitives
   in
-  if dynlink
+  let link_is_last = (not run_dce) && not run_opt in
+  with_step_output ~is_last:link_is_last "wasm-merged"
+  @@ fun ~file:linked ~opt_sm:opt_linked_sm ->
+  link ~output_file:linked ~opt_output_sourcemap:opt_linked_sm;
+  if link_is_last
+  then finish (Linker.list_all ())
+  else if run_dce
   then
-    optimize_and_finish
-      ~opt_input_sourcemap:opt_temp_sourcemap
-      ~input_file:temp_file
-      (Linker.list_all ())
-  else
-    Fs.with_intermediate_file (Filename.temp_file "wasm-dce" ".wasm")
-    @@ fun temp_file' ->
-    opt_with
-      Fs.with_intermediate_file
-      (if enable_source_maps
-       then Some (Filename.temp_file "wasm-dce" ".wasm.map")
-       else None)
-    @@ fun opt_temp_sourcemap' ->
-    let t = Timer.make ~get_time:Unix.time () in
+    let dce_is_last = not run_opt in
+    with_step_output ~is_last:dce_is_last "wasm-dce"
+    @@ fun ~file:dced ~opt_sm:opt_dced_sm ->
     let primitives =
-      Binaryen.dead_code_elimination
-        ~dependencies:Runtime_files.dependencies
-        ~opt_input_sourcemap:opt_temp_sourcemap
-        ~opt_output_sourcemap:opt_temp_sourcemap'
-        ~input_file:temp_file
-        ~output_file:temp_file'
+      dce
+        ~input_file:linked
+        ~opt_input_sourcemap:opt_linked_sm
+        ~output_file:dced
+        ~opt_output_sourcemap:opt_dced_sm
     in
-    if binaryen_times () then Format.eprintf "  binaryen dce: %a@." Timer.print t;
-    optimize_and_finish
-      ~opt_input_sourcemap:opt_temp_sourcemap'
-      ~input_file:temp_file'
-      primitives
+    if dce_is_last
+    then finish primitives
+    else (
+      optimize ~input_file:dced ~opt_input_sourcemap:opt_dced_sm;
+      finish primitives)
+  else (
+    (* [dynlink] + O2/O3: skip DCE, go straight to [wasm-opt]. *)
+    optimize ~input_file:linked ~opt_input_sourcemap:opt_linked_sm;
+    finish (Linker.list_all ()))
 
 let link_runtime ~profile runtime_wasm_files output_file =
   if List.is_empty runtime_wasm_files
@@ -275,6 +302,7 @@ let generate_prelude ~out_file =
   let context = Generate.start () in
   let _ =
     Generate.f
+      ~profile
       ~context
       ~unit_name:(Some "prelude")
       ~live_vars:variable_uses
@@ -488,6 +516,7 @@ let run
     let context = Generate.start () in
     let toplevel_name, generated_js =
       Generate.f
+        ~profile
         ~context
         ~unit_name
         ~live_vars:variable_uses
@@ -579,31 +608,45 @@ let run
           else None)
        @@ fun opt_tmp_map_file ->
        let unit_data, shapes =
-         Fs.with_intermediate_file (Filename.temp_file unit_name ".wasm")
-         @@ fun input_file ->
-         opt_with
-           Fs.with_intermediate_file
-           (if enable_source_maps
-            then Some (Filename.temp_file unit_name ".wasm.map")
-            else None)
-         @@ fun opt_input_sourcemap ->
-         let fragments, shapes =
-           output
-             code
-             ~wat_file:
-               (Filename.concat (Filename.dirname output_file) (unit_name ^ ".wat"))
-             ~unit_name:(Some unit_name)
-             ~file:input_file
-             ~opt_source_map_file:opt_input_sourcemap
-         in
-         Binaryen.optimize
-           ~profile
-           ~opt_input_sourcemap
-           ~opt_output_sourcemap:opt_tmp_map_file
-           ~input_file
-           ~output_file:tmp_wasm_file
-           ();
-         { Link.unit_name; unit_info; fragments }, shapes
+         match profile with
+         | Profile.O1 ->
+             (* At O1, skip Binaryen.optimize — write directly *)
+             let fragments, shapes =
+               output
+                 code
+                 ~wat_file:
+                   (Filename.concat (Filename.dirname output_file) (unit_name ^ ".wat"))
+                 ~unit_name:(Some unit_name)
+                 ~file:tmp_wasm_file
+                 ~opt_source_map_file:opt_tmp_map_file
+             in
+             { Link.unit_name; unit_info; fragments }, shapes
+         | O2 | O3 ->
+             Fs.with_intermediate_file (Filename.temp_file unit_name ".wasm")
+             @@ fun input_file ->
+             opt_with
+               Fs.with_intermediate_file
+               (if enable_source_maps
+                then Some (Filename.temp_file unit_name ".wasm.map")
+                else None)
+             @@ fun opt_input_sourcemap ->
+             let fragments, shapes =
+               output
+                 code
+                 ~wat_file:
+                   (Filename.concat (Filename.dirname output_file) (unit_name ^ ".wat"))
+                 ~unit_name:(Some unit_name)
+                 ~file:input_file
+                 ~opt_source_map_file:opt_input_sourcemap
+             in
+             Binaryen.optimize
+               ~profile
+               ~opt_input_sourcemap
+               ~opt_output_sourcemap:opt_tmp_map_file
+               ~input_file
+               ~output_file:tmp_wasm_file
+               ();
+             { Link.unit_name; unit_info; fragments }, shapes
        in
        cont unit_data unit_name tmp_wasm_file opt_tmp_map_file shapes cmi_files
      in

compiler/lib-wasm/gc_target.ml

@@ -2041,7 +2041,33 @@ let handle_exceptions ~result_typ ~fall_through ~context body x exn_handler =
      let* () = no_event in
      exn_handler ~result_typ ~fall_through ~context)
 
-let post_process_function_body = Initialize_locals.f
+let post_process_function_body ~profile ~param_names ~param_types ~locals body =
+  (* At [--opt 1] we skip [wasm-opt] entirely (both for .cmo/.cma and
+     for executables), so our own passes are the only ones tightening
+     the body. [Local_sink] runs first: shortening live ranges and
+     dropping [local.set]s simplifies the input to [Var_coalescing]. *)
+  let body =
+    match (profile : Profile.t) with
+    | O1 when Config.Flag.wasm_local_sink () -> Local_sink.f body
+    | O1 | O2 | O3 -> body
+  in
+  let locals, body =
+    match (profile : Profile.t) with
+    | O1 when Config.Flag.wasm_var_coalescing () ->
+        Var_coalescing.f ~param_names ~param_types ~locals body
+    | O1 | O2 | O3 -> locals, body
+  in
+  let locals, body = Initialize_locals.f ~param_names ~locals body in
+  (* Reorder locals so frequently-used ones get low Wasm indices
+     (one-byte LEB128 encoding for indices < 128). Gated on [O1] to
+     match the rest of this pipeline; at [O2]/[O3] [wasm-opt] handles
+     local reordering. *)
+  let locals =
+    match (profile : Profile.t) with
+    | O1 when Config.Flag.wasm_reorder_locals () -> Reorder_locals.f ~locals body
+    | O1 | O2 | O3 -> locals
+  in
+  locals, body
 
 let entry_point ~toplevel_fun =
   let code =