diff --git a/compiler/bin-js_of_ocaml/compile.ml b/compiler/bin-js_of_ocaml/compile.ml
index d3e924e807..ba99440925 100644
--- a/compiler/bin-js_of_ocaml/compile.ml
+++ b/compiler/bin-js_of_ocaml/compile.ml
@@ -285,7 +285,7 @@ let run
   | `None ->
       let prims = Linker.list_all () |> StringSet.elements in
       assert (List.length prims > 0);
-      let code, uinfo = Parse_bytecode.predefined_exceptions ~target:`JavaScript in
+      let code, uinfo = Parse_bytecode.predefined_exceptions in
       let uinfo = { uinfo with primitives = uinfo.primitives @ prims } in
       let code : Parse_bytecode.one =
         { code
@@ -331,7 +331,6 @@ let run
           let linkall = linkall || toplevel || dynlink in
           let code =
             Parse_bytecode.from_exe
-              ~target:`JavaScript
               ~includes:include_dirs
               ~include_cmis
               ~link_info:(toplevel || dynlink)
@@ -364,7 +363,6 @@ let run
           let t1 = Timer.make () in
           let code =
             Parse_bytecode.from_cmo
-              ~target:`JavaScript
               ~includes:include_dirs
               ~include_cmis
               ~debug:need_debug
@@ -421,7 +419,6 @@ let run
               let t1 = Timer.make () in
               let code =
                 Parse_bytecode.from_cmo
-                  ~target:`JavaScript
                   ~includes:include_dirs
                   ~include_cmis
                   ~debug:need_debug
@@ -453,7 +450,6 @@ let run
                 let t1 = Timer.make () in
                 let code =
                   Parse_bytecode.from_cmo
-                    ~target:`JavaScript
                     ~includes:include_dirs
                     ~include_cmis
                     ~debug:need_debug
diff --git a/compiler/lib/config.ml b/compiler/lib/config.ml
index 7865b6fd33..caf8f55be6 100644
--- a/compiler/lib/config.ml
+++ b/compiler/lib/config.ml
@@ -183,8 +183,11 @@ end
 
 (****)
 
-let target_ : [ `JavaScript | `Wasm ] ref = ref `JavaScript
+let target_ : [ `JavaScript | `Wasm ] option ref = ref (Some `JavaScript)
 
-let target () = !target_
+let target () =
+  match !target_ with
+  | Some t -> t
+  | None -> failwith "target was not set"
 
-let set_target t = target_ := t
+let set_target t = target_ := Some t
diff --git a/compiler/lib/driver.ml b/compiler/lib/driver.ml
index b50df74d65..8836bf82a4 100644
--- a/compiler/lib/driver.ml
+++ b/compiler/lib/driver.ml
@@ -670,7 +670,19 @@ let link_and_pack ?(standalone = true) ?(wrap_with_fun = `Iife) ?(link = `No) p
   |> coloring
   |> check_js
 
-let optimize ~profile ~deadcode_sentinal p =
+type optimized_result =
+  { program : Code.program
+  ; variable_uses : Deadcode.variable_uses
+  ; trampolined_calls : Effects.trampolined_calls
+  ; in_cps : Effects.in_cps
+  ; deadcode_sentinal : Code.Var.t
+  }
+
+let optimize ~profile p =
+  let deadcode_sentinal =
+    (* If deadcode is disabled, this field is just fresh variable *)
+    Code.Var.fresh_n "undef"
+  in
   let opt =
     specialize_js_once
     +> (match profile with
@@ -687,16 +699,14 @@ let optimize ~profile ~deadcode_sentinal p =
   in
   if times () then Format.eprintf "Start Optimizing...@.";
   let t = Timer.make () in
-  let r = opt p in
+  let (program, variable_uses), trampolined_calls, in_cps = opt p in
   let () = if times () then Format.eprintf " optimizations : %a@." Timer.print t in
-  r
+  { program; variable_uses; trampolined_calls; in_cps; deadcode_sentinal }
 
 let full ~standalone ~wrap_with_fun ~profile ~link ~source_map ~formatter d p =
-  let deadcode_sentinal =
-    (* If deadcode is disabled, this field is just fresh variable *)
-    Code.Var.fresh_n "undef"
+  let { program; variable_uses; trampolined_calls; in_cps; deadcode_sentinal } =
+    optimize ~profile p
   in
-  let r = optimize ~profile ~deadcode_sentinal p in
   let exported_runtime = not standalone in
   let emit formatter =
     generate
@@ -708,7 +718,7 @@ let full ~standalone ~wrap_with_fun ~profile ~link ~source_map ~formatter d p =
     +> link_and_pack ~standalone ~wrap_with_fun ~link
     +> output formatter ~source_map ()
   in
-  let source_map = emit formatter r in
+  let source_map = emit formatter ((program, variable_uses), trampolined_calls, in_cps) in
   source_map
 
 let full_no_source_map ~formatter ~standalone ~wrap_with_fun ~profile ~link d p =
diff --git a/compiler/lib/driver.mli b/compiler/lib/driver.mli
index 7f3e16bb4f..91f846b989 100644
--- a/compiler/lib/driver.mli
+++ b/compiler/lib/driver.mli
@@ -20,13 +20,15 @@
 
 type profile
 
-val optimize :
-     profile:profile
-  -> deadcode_sentinal:Code.Var.t
-  -> Code.program
-  -> (Code.program * Deadcode.variable_uses)
-     * Effects.trampolined_calls
-     * Effects.trampolined_calls
+type optimized_result =
+  { program : Code.program
+  ; variable_uses : Deadcode.variable_uses
+  ; trampolined_calls : Effects.trampolined_calls
+  ; in_cps : Effects.in_cps
+  ; deadcode_sentinal : Code.Var.t
+  }
+
+val optimize : profile:profile -> Code.program -> optimized_result
 
 val f :
      ?standalone:bool
diff --git a/compiler/lib/eval.ml b/compiler/lib/eval.ml
index 2242ef1ce0..ab4183f302 100644
--- a/compiler/lib/eval.ml
+++ b/compiler/lib/eval.ml
@@ -47,6 +47,8 @@ module Int32 = struct
     match l with
     | [ Int i; Int j ] -> Some (Int (f i (to_int j)))
     | _ -> None
+
+  let numbits = 32
 end
 
 module Int31 = struct
@@ -71,6 +73,8 @@ module Int31 = struct
     | [ Int i; Int j ] ->
         Some (Int (to_int32 (f (of_int32_warning_on_overflow i) (Int32.to_int j))))
     | _ -> None
+
+  let numbits = 31
 end
 
 let float_binop_aux (l : constant list) (f : float -> float -> 'a) : 'a option =
@@ -114,9 +118,15 @@ module type Int = sig
   val int_binop : constant list -> (t -> t -> t) -> constant option
 
   val shift_op : constant list -> (t -> int -> t) -> constant option
+
+  val of_int32_warning_on_overflow : int32 -> t
+
+  val to_int32 : t -> int32
+
+  val numbits : int
 end
 
-let eval_prim x =
+let eval_prim ~target x =
   match x with
   | Not, [ Int i ] -> bool Int32.(i = 0l)
   | Lt, [ Int i; Int j ] -> bool Int32.(i < j)
@@ -127,8 +137,15 @@ let eval_prim x =
   | Extern name, l -> (
       let name = Primitive.resolve name in
       let (module Int : Int) =
-        match Config.target () with
-        | `JavaScript -> (module Int32)
+        match target with
+        | `JavaScript ->
+            (module struct
+              include Int32
+
+              let of_int32_warning_on_overflow = Fun.id
+
+              let to_int32 = Fun.id
+            end)
         | `Wasm -> (module Int31)
       in
       match name, l with
@@ -158,7 +175,9 @@ let eval_prim x =
       | "caml_mul_float", _ -> float_binop l ( *. )
       | "caml_div_float", _ -> float_binop l ( /. )
       | "caml_fmod_float", _ -> float_binop l mod_float
-      | "caml_int_of_float", [ Float f ] -> Some (Int (Int32.of_float f))
+      | "caml_int_of_float", [ Float f ] ->
+          Some
+            (Int (Int32.of_float f |> Int.of_int32_warning_on_overflow |> Int.to_int32))
       | "to_int", [ Float f ] -> Some (Int (Int32.of_float f))
       | "to_int", [ Int i ] -> Some (Int i)
       (* Math *)
@@ -190,12 +209,7 @@ let eval_prim x =
           | Some env -> Some (String env)
           | None -> None)
       | "caml_sys_const_word_size", [ _ ] -> Some (Int 32l)
-      | "caml_sys_const_int_size", [ _ ] ->
-          Some
-            (Int
-               (match Config.target () with
-               | `JavaScript -> 32l
-               | `Wasm -> 31l))
+      | "caml_sys_const_int_size", [ _ ] -> Some (Int (Int32.of_int Int.numbits))
       | "caml_sys_const_big_endian", [ _ ] -> Some (Int 0l)
       | "caml_sys_const_naked_pointers_checked", [ _ ] -> Some (Int 0l)
       | _ -> None)
@@ -222,7 +236,7 @@ type is_int =
   | N
   | Unknown
 
-let is_int info x =
+let is_int ~target info x =
   match x with
   | Pv x ->
       get_approx
@@ -231,7 +245,7 @@ let is_int info x =
           match Flow.Info.def info x with
           | Some (Constant (Int _)) -> Y
           | Some (Constant (NativeInt _ | Int32 _)) ->
-              assert (Poly.equal (Config.target ()) `Wasm);
+              assert (Poly.equal target `Wasm);
               N
           | Some (Block (_, _, _, _) | Constant _) -> N
           | None | Some _ -> Unknown)
@@ -244,7 +258,7 @@ let is_int info x =
         x
   | Pc (Int _) -> Y
   | Pc (NativeInt _ | Int32 _) ->
-      assert (Poly.equal (Config.target ()) `Wasm);
+      assert (Poly.equal target `Wasm);
       N
   | Pc _ -> N
 
@@ -316,7 +330,7 @@ let constant_js_equal a b =
   | Tuple _, _
   | _, Tuple _ -> None
 
-let eval_instr info ((x, loc) as i) =
+let eval_instr ~target info ((x, loc) as i) =
   match x with
   | Let (x, Prim (Extern (("caml_equal" | "caml_notequal") as prim), [ y; z ])) -> (
       match the_const_of info y, the_const_of info z with
@@ -373,7 +387,7 @@ let eval_instr info ((x, loc) as i) =
            below fail. *)
       [ i ]
   | Let (x, Prim (IsInt, [ y ])) -> (
-      match is_int info y with
+      match is_int ~target info y with
       | Unknown -> [ i ]
       | (Y | N) as b ->
           let c = Constant (bool' Poly.(b = Y)) in
@@ -389,7 +403,7 @@ let eval_instr info ((x, loc) as i) =
   | Let (x, Prim (Extern "caml_sys_const_backend_type", [ _ ])) ->
       let jsoo = Code.Var.fresh () in
       let backend_name =
-        match Config.target () with
+        match target with
         | `JavaScript -> "js_of_ocaml"
         | `Wasm -> "wasm_of_ocaml"
       in
@@ -406,6 +420,7 @@ let eval_instr info ((x, loc) as i) =
                | _ -> false)
         then
           eval_prim
+            ~target
             ( prim
             , List.map prim_args' ~f:(function
                   | Some c -> c
@@ -423,9 +438,13 @@ let eval_instr info ((x, loc) as i) =
                 , Prim
                     ( prim
                     , List.map2 prim_args prim_args' ~f:(fun arg (c : constant option) ->
-                          match c, Config.target () with
-                          | ( Some ((Int _ | Int32 _ | NativeInt _ | NativeString _) as c)
-                            , _ ) -> Pc c
+                          match c, target with
+                          | Some ((Int _ | NativeString _) as c), _ -> Pc c
+                          | Some ((Int32 _ | NativeInt _) as c), `Wasm -> Pc c
+                          | Some (Int32 _ | NativeInt _), `JavaScript ->
+                              invalid_arg
+                                "Constant of type Int32 or NativeInt unexpected in the \
+                                 JavaScript backend"
                           | Some (Float _ as c), `JavaScript -> Pc c
                           | Some (String _ as c), `JavaScript
                             when Config.Flag.use_js_string () -> Pc c
@@ -554,15 +573,15 @@ let drop_exception_handler blocks =
     blocks
     blocks
 
-let eval info blocks =
+let eval ~target info blocks =
   Addr.Map.map
     (fun block ->
-      let body = List.concat_map block.body ~f:(eval_instr info) in
+      let body = List.concat_map block.body ~f:(eval_instr ~target info) in
       let branch = eval_branch info block.branch in
       { block with Code.body; Code.branch })
     blocks
 
 let f info p =
-  let blocks = eval info p.blocks in
+  let blocks = eval ~target:(Config.target ()) info p.blocks in
   let blocks = drop_exception_handler blocks in
   { p with blocks }
diff --git a/compiler/lib/link_js.ml b/compiler/lib/link_js.ml
index 4fa3778fb9..e4d3d2989e 100644
--- a/compiler/lib/link_js.ml
+++ b/compiler/lib/link_js.ml
@@ -412,13 +412,7 @@ let link ~output ~linkall ~mklib ~toplevel ~files ~resolve_sourcemap_url ~source
             List.fold_left units ~init:StringSet.empty ~f:(fun acc (u : Unit_info.t) ->
                 StringSet.union acc (StringSet.of_list u.primitives))
           in
-          let code =
-            Parse_bytecode.link_info
-              ~target:`JavaScript
-              ~symbols:!sym
-              ~primitives
-              ~crcs:[]
-          in
+          let code = Parse_bytecode.link_info ~symbols:!sym ~primitives ~crcs:[] in
           let b = Buffer.create 100 in
           let fmt = Pretty_print.to_buffer b in
           Driver.configure fmt;
diff --git a/compiler/lib/ocaml_compiler.ml b/compiler/lib/ocaml_compiler.ml
index d8020a8411..2518753d5f 100644
--- a/compiler/lib/ocaml_compiler.ml
+++ b/compiler/lib/ocaml_compiler.ml
@@ -18,13 +18,13 @@
 
 open! Stdlib
 
-let rec constant_of_const ~target c : Code.constant =
+let rec constant_of_const c : Code.constant =
   let open Lambda in
   let open Asttypes in
   match c with
   | Const_base (Const_int i) ->
       Int
-        (match target with
+        (match Config.target () with
         | `JavaScript -> Int32.of_int_warning_on_overflow i
         | `Wasm -> Int31.(of_int_warning_on_overflow i |> to_int32))
   | Const_base (Const_char c) -> Int (Int32.of_int (Char.code c))
@@ -40,11 +40,11 @@ let rec constant_of_const ~target c : Code.constant =
       Float_array (Array.of_list l)
   | ((Const_pointer i) [@if ocaml_version < (4, 12, 0)]) ->
       Int
-        (match target with
+        (match Config.target () with
         | `JavaScript -> Int32.of_int_warning_on_overflow i
         | `Wasm -> Int31.(of_int_warning_on_overflow i |> to_int32))
   | Const_block (tag, l) ->
-      let l = Array.of_list (List.map l ~f:(fun c -> constant_of_const ~target c)) in
+      let l = Array.of_list (List.map l ~f:(fun c -> constant_of_const c)) in
       Tuple (tag, l, Unknown)
 
 let rec find_loc_in_summary ident' = function
diff --git a/compiler/lib/ocaml_compiler.mli b/compiler/lib/ocaml_compiler.mli
index 409381a562..227f1b9f31 100644
--- a/compiler/lib/ocaml_compiler.mli
+++ b/compiler/lib/ocaml_compiler.mli
@@ -16,8 +16,7 @@
  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  *)
 
-val constant_of_const :
-  target:[ `JavaScript | `Wasm ] -> Lambda.structured_constant -> Code.constant
+val constant_of_const : Lambda.structured_constant -> Code.constant
 
 val find_loc_in_summary : Ident.t -> Env.summary -> Location.t option
 
diff --git a/compiler/lib/parse_bytecode.ml b/compiler/lib/parse_bytecode.ml
index 4611259751..0db004cdf9 100644
--- a/compiler/lib/parse_bytecode.ml
+++ b/compiler/lib/parse_bytecode.ml
@@ -443,7 +443,7 @@ end
 
 (* Parse constants *)
 module Constants : sig
-  val parse : target:[ `JavaScript | `Wasm ] -> Obj.t -> Code.constant
+  val parse : Obj.t -> Code.constant
 
   val inlined : Code.constant -> bool
 end = struct
@@ -477,7 +477,7 @@ end = struct
 
   let ident_native = ident_of_custom (Obj.repr 0n)
 
-  let rec parse ~target x =
+  let rec parse x =
     if Obj.is_block x
     then
       let tag = Obj.tag x in
@@ -503,15 +503,12 @@ end = struct
         | None -> assert false
       else if tag < Obj.no_scan_tag
       then
-        Tuple
-          ( tag
-          , Array.init (Obj.size x) ~f:(fun i -> parse ~target (Obj.field x i))
-          , Unknown )
+        Tuple (tag, Array.init (Obj.size x) ~f:(fun i -> parse (Obj.field x i)), Unknown)
       else assert false
     else
       let i : int = Obj.magic x in
       Int
-        (match target with
+        (match Config.target () with
         | `JavaScript -> Int32.of_int_warning_on_overflow i
         | `Wasm -> Int31.(of_int_warning_on_overflow i |> to_int32))
 
@@ -769,10 +766,10 @@ let access_global g i =
       g.vars.(i) <- Some x;
       x
 
-let register_global ~target ?(force = false) g i loc rem =
+let register_global ?(force = false) g i loc rem =
   if g.is_exported.(i)
      &&
-     match target with
+     match Config.target () with
      | `Wasm -> true
      | `JavaScript -> false
   then (
@@ -805,7 +802,7 @@ let register_global ~target ?(force = false) g i loc rem =
     :: rem
   else rem
 
-let get_global ~target state instrs i loc =
+let get_global state instrs i loc =
   State.size_globals state (i + 1);
   let g = State.globals state in
   match g.vars.(i) with
@@ -820,7 +817,7 @@ let get_global ~target state instrs i loc =
         x, state, (Let (x, Constant cst), loc) :: instrs
       else if i < Array.length g.constants
               ||
-              match target with
+              match Config.target () with
               | `Wasm -> false
               | `JavaScript -> true
       then (
@@ -853,7 +850,6 @@ type compile_info =
   ; code : string
   ; limit : int
   ; debug : Debug.t
-  ; target : [ `JavaScript | `Wasm ]
   }
 
 let string_of_addr debug_data addr =
@@ -881,7 +877,7 @@ let ( ||| ) x y =
   | No -> y
   | _ -> x
 
-let rec compile_block blocks debug_data ~target code pc state =
+let rec compile_block blocks debug_data code pc state =
   match Addr.Map.find_opt pc !tagged_blocks with
   | Some old_state -> (
       (* Check that the shape of the stack is compatible with the one used to compile the block *)
@@ -913,7 +909,7 @@ let rec compile_block blocks debug_data ~target code pc state =
       let state = State.start_block pc state in
       tagged_blocks := Addr.Map.add pc state !tagged_blocks;
       let instr, last, state' =
-        compile { blocks; code; limit; debug = debug_data; target } pc state []
+        compile { blocks; code; limit; debug = debug_data } pc state []
       in
       assert (not (Addr.Map.mem pc !compiled_blocks));
       (* When jumping to a block that was already visited and the
@@ -942,11 +938,10 @@ let rec compile_block blocks debug_data ~target code pc state =
       in
       compiled_blocks := Addr.Map.add pc (state, List.rev instr, last) !compiled_blocks;
       match fst last with
-      | Branch (pc', _) ->
-          compile_block blocks debug_data ~target code pc' (adjust_state pc')
+      | Branch (pc', _) -> compile_block blocks debug_data code pc' (adjust_state pc')
       | Cond (_, (pc1, _), (pc2, _)) ->
-          compile_block blocks debug_data ~target code pc1 (adjust_state pc1);
-          compile_block blocks debug_data ~target code pc2 (adjust_state pc2)
+          compile_block blocks debug_data code pc1 (adjust_state pc1);
+          compile_block blocks debug_data code pc2 (adjust_state pc2)
       | Poptrap (_, _) -> ()
       | Switch (_, _) -> ()
       | Raise _ | Return _ | Stop -> ()
@@ -1288,7 +1283,7 @@ and compile infos pc state instrs =
         let params, state' = State.make_stack nparams state' loc in
         if debug_parser () then Format.printf ") {@.";
         let state' = State.clear_accu state' in
-        compile_block infos.blocks infos.debug ~target:infos.target code addr state';
+        compile_block infos.blocks infos.debug code addr state';
         if debug_parser () then Format.printf "}@.";
         let args = State.stack_vars state' in
         let state'', _, _ = Addr.Map.find addr !compiled_blocks in
@@ -1345,7 +1340,7 @@ and compile infos pc state instrs =
               let params, state' = State.make_stack nparams state' loc in
               if debug_parser () then Format.printf ") {@.";
               let state' = State.clear_accu state' in
-              compile_block infos.blocks infos.debug ~target:infos.target code addr state';
+              compile_block infos.blocks infos.debug code addr state';
               if debug_parser () then Format.printf "}@.";
               let args = State.stack_vars state' in
               let state'', _, _ = Addr.Map.find addr !compiled_blocks in
@@ -1375,16 +1370,16 @@ and compile infos pc state instrs =
         compile infos (pc + 2) (State.env_acc n state) instrs
     | GETGLOBAL ->
         let i = getu code (pc + 1) in
-        let _, state, instrs = get_global ~target:infos.target state instrs i loc in
+        let _, state, instrs = get_global state instrs i loc in
         compile infos (pc + 2) state instrs
     | PUSHGETGLOBAL ->
         let state = State.push state loc in
         let i = getu code (pc + 1) in
-        let _, state, instrs = get_global ~target:infos.target state instrs i loc in
+        let _, state, instrs = get_global state instrs i loc in
         compile infos (pc + 2) state instrs
     | GETGLOBALFIELD ->
         let i = getu code (pc + 1) in
-        let x, state, instrs = get_global ~target:infos.target state instrs i loc in
+        let x, state, instrs = get_global state instrs i loc in
         let j = getu code (pc + 2) in
         let y, state = State.fresh_var state loc in
         if debug_parser () then Format.printf "%a = %a[%d]@." Var.print y Var.print x j;
@@ -1393,7 +1388,7 @@ and compile infos pc state instrs =
         let state = State.push state loc in
 
         let i = getu code (pc + 1) in
-        let x, state, instrs = get_global ~target:infos.target state instrs i loc in
+        let x, state, instrs = get_global state instrs i loc in
         let j = getu code (pc + 2) in
         let y, state = State.fresh_var state loc in
         if debug_parser () then Format.printf "%a = %a[%d]@." Var.print y Var.print x j;
@@ -1418,7 +1413,7 @@ and compile infos pc state instrs =
         in
         let x, state = State.fresh_var state loc in
         if debug_parser () then Format.printf "%a = 0@." Var.print x;
-        let instrs = register_global ~target:infos.target g i loc instrs in
+        let instrs = register_global g i loc instrs in
         compile infos (pc + 2) state ((Let (x, const 0l), loc) :: instrs)
     | ATOM0 ->
         let x, state = State.fresh_var state loc in
@@ -1766,9 +1761,9 @@ and compile infos pc state instrs =
         let it = Array.init isize ~f:(fun i -> base + gets code (base + i)) in
         let bt = Array.init bsize ~f:(fun i -> base + gets code (base + isize + i)) in
         Array.iter it ~f:(fun pc' ->
-            compile_block infos.blocks infos.debug ~target:infos.target code pc' state);
+            compile_block infos.blocks infos.debug code pc' state);
         Array.iter bt ~f:(fun pc' ->
-            compile_block infos.blocks infos.debug ~target:infos.target code pc' state);
+            compile_block infos.blocks infos.debug code pc' state);
         match isize, bsize with
         | _, 0 -> instrs, (Switch (x, Array.map it ~f:(fun pc -> pc, [])), loc), state
         | 0, _ ->
@@ -1839,17 +1834,10 @@ and compile infos pc state instrs =
                   , (handler_addr, State.stack_vars handler_state) )
               , loc ) )
             !compiled_blocks;
+        compile_block infos.blocks infos.debug code handler_addr handler_state;
         compile_block
           infos.blocks
           infos.debug
-          ~target:infos.target
-          code
-          handler_addr
-          handler_state;
-        compile_block
-          infos.blocks
-          infos.debug
-          ~target:infos.target
           code
           body_addr
           { (State.push_handler handler_ctx_state) with
@@ -1867,7 +1855,6 @@ and compile infos pc state instrs =
         compile_block
           infos.blocks
           infos.debug
-          ~target:infos.target
           code
           addr
           (State.pop 4 (State.pop_handler state));
@@ -2551,7 +2538,7 @@ type one =
   ; debug : Debug.t
   }
 
-let parse_bytecode code globals debug_data ~target =
+let parse_bytecode code globals debug_data =
   let state = State.initial globals in
   Code.Var.reset ();
   let blocks = Blocks.analyse debug_data code in
@@ -2566,7 +2553,7 @@ let parse_bytecode code globals debug_data ~target =
     if not (Blocks.is_empty blocks')
     then (
       let start = 0 in
-      compile_block blocks' debug_data ~target code start state;
+      compile_block blocks' debug_data code start state;
       let blocks =
         Addr.Map.mapi
           (fun _ (state, instr, last) ->
@@ -2686,7 +2673,6 @@ type bytesections =
 [@@ocaml.warning "-unused-field"]
 
 let from_exe
-    ~target
     ?(includes = [])
     ~linkall
     ~link_info
@@ -2700,7 +2686,7 @@ let from_exe
   let primitive_table = Array.of_list primitives in
   let code = Toc.read_code toc ic in
   let init_data = Toc.read_data toc ic in
-  let init_data = Array.map ~f:(Constants.parse ~target) init_data in
+  let init_data = Array.map ~f:Constants.parse init_data in
   let orig_symbols = Toc.read_symb toc ic in
   let orig_crcs = Toc.read_crcs toc ic in
   let keeps =
@@ -2755,12 +2741,12 @@ let from_exe
     Ocaml_compiler.Symtable.GlobalMap.iter symbols ~f:(fun id n ->
         globals.named_value.(n) <- Some (Ocaml_compiler.Symtable.Global.name id);
         globals.is_exported.(n) <- true);
-  let p = parse_bytecode code globals debug_data ~target in
+  let p = parse_bytecode code globals debug_data in
   (* register predefined exception *)
   let body =
     List.fold_left predefined_exceptions ~init:[] ~f:(fun body (i, name) ->
         globals.named_value.(i) <- Some name;
-        let body = register_global ~target ~force:true globals i noloc body in
+        let body = register_global ~force:true globals i noloc body in
         globals.is_exported.(i) <- false;
         body)
   in
@@ -2768,7 +2754,7 @@ let from_exe
     Array.fold_right_i globals.constants ~init:body ~f:(fun i _ l ->
         match globals.vars.(i) with
         | Some x when globals.is_const.(i) ->
-            let l = register_global ~target globals i noloc l in
+            let l = register_global globals i noloc l in
             (Let (x, Constant globals.constants.(i)), noloc) :: l
         | _ -> l)
   in
@@ -2787,8 +2773,8 @@ let from_exe
       let gdata = Var.fresh () in
       let need_gdata = ref false in
       let infos =
-        [ "sections", Constants.parse ~target (Obj.repr sections)
-        ; "symbols", Constants.parse ~target (Obj.repr symbols_array)
+        [ "sections", Constants.parse (Obj.repr sections)
+        ; "symbols", Constants.parse (Obj.repr symbols_array)
         ; "prim_count", Int (Int32.of_int (Array.length globals.primitives))
         ]
       in
@@ -2879,7 +2865,7 @@ let from_bytes ~prims ~debug (code : bytecode) =
     t
   in
   let globals = make_globals 0 [||] prims in
-  let p = parse_bytecode code globals debug_data ~target:`JavaScript in
+  let p = parse_bytecode code globals debug_data in
   let gdata = Var.fresh_n "global_data" in
   let need_gdata = ref false in
   let find_name i =
@@ -2944,13 +2930,13 @@ module Reloc = struct
   let constant_of_const x = Constants.parse x [@@if ocaml_version >= (5, 1, 0)]
 
   (* We currently rely on constants to be relocated before globals. *)
-  let step1 ~target t compunit code =
+  let step1 t compunit code =
     if t.step2_started then assert false;
     let open Cmo_format in
     List.iter compunit.cu_primitives ~f:(fun name ->
         Hashtbl.add t.primitives name (Hashtbl.length t.primitives));
     let slot_for_literal sc =
-      t.constants <- constant_of_const ~target sc :: t.constants;
+      t.constants <- constant_of_const sc :: t.constants;
       let pos = t.pos in
       t.pos <- succ t.pos;
       pos
@@ -3018,16 +3004,16 @@ module Reloc = struct
     globals
 end
 
-let from_compilation_units ~target ~includes:_ ~include_cmis ~debug_data l =
+let from_compilation_units ~includes:_ ~include_cmis ~debug_data l =
   let reloc = Reloc.create () in
-  List.iter l ~f:(fun (compunit, code) -> Reloc.step1 ~target reloc compunit code);
+  List.iter l ~f:(fun (compunit, code) -> Reloc.step1 reloc compunit code);
   List.iter l ~f:(fun (compunit, code) -> Reloc.step2 reloc compunit code);
   let globals = Reloc.make_globals reloc in
   let code =
     let l = List.map l ~f:(fun (_, c) -> Bytes.to_string c) in
     String.concat ~sep:"" l
   in
-  let prog = parse_bytecode code globals debug_data ~target in
+  let prog = parse_bytecode code globals debug_data in
   let gdata = Var.fresh_n "global_data" in
   let need_gdata = ref false in
   let body =
@@ -3036,7 +3022,7 @@ let from_compilation_units ~target ~includes:_ ~include_cmis ~debug_data l =
         | Some x when globals.is_const.(i) -> (
             match globals.named_value.(i) with
             | None ->
-                let l = register_global ~target globals i noloc l in
+                let l = register_global globals i noloc l in
                 let cst = globals.constants.(i) in
                 (match cst, Code.Var.get_name x with
                 | String str, None -> Code.Var.name x (Printf.sprintf "cst_%s" str)
@@ -3069,8 +3055,7 @@ let from_compilation_units ~target ~includes:_ ~include_cmis ~debug_data l =
   in
   { code = prepend prog body; cmis; debug = debug_data }
 
-let from_cmo ~target ?(includes = []) ?(include_cmis = false) ?(debug = false) compunit ic
-    =
+let from_cmo ?(includes = []) ?(include_cmis = false) ?(debug = false) compunit ic =
   let debug_data = Debug.create ~include_cmis debug in
   seek_in ic compunit.Cmo_format.cu_pos;
   let code = Bytes.create compunit.Cmo_format.cu_codesize in
@@ -3081,13 +3066,11 @@ let from_cmo ~target ?(includes = []) ?(include_cmis = false) ?(debug = false) c
     seek_in ic compunit.Cmo_format.cu_debug;
     Debug.read_event_list debug_data ~crcs:[] ~includes ~orig:0 ic);
   if times () then Format.eprintf "    read debug events: %a@." Timer.print t;
-  let p =
-    from_compilation_units ~target ~includes ~include_cmis ~debug_data [ compunit, code ]
-  in
+  let p = from_compilation_units ~includes ~include_cmis ~debug_data [ compunit, code ] in
   Code.invariant p.code;
   p
 
-let from_cma ~target ?(includes = []) ?(include_cmis = false) ?(debug = false) lib ic =
+let from_cma ?(includes = []) ?(include_cmis = false) ?(debug = false) lib ic =
   let debug_data = Debug.create ~include_cmis debug in
   let orig = ref 0 in
   let t = ref 0. in
@@ -3106,7 +3089,7 @@ let from_cma ~target ?(includes = []) ?(include_cmis = false) ?(debug = false) l
         compunit, code)
   in
   if times () then Format.eprintf "    read debug events: %.2f@." !t;
-  let p = from_compilation_units ~target ~includes ~include_cmis ~debug_data units in
+  let p = from_compilation_units ~includes ~include_cmis ~debug_data units in
   Code.invariant p.code;
   p
 
@@ -3151,7 +3134,7 @@ let from_channel ic =
           `Exe
       | _ -> raise Magic_number.(Bad_magic_number (to_string magic)))
 
-let predefined_exceptions ~target =
+let predefined_exceptions =
   let body =
     let open Code in
     List.map predefined_exceptions ~f:(fun (index, name) ->
@@ -3161,7 +3144,7 @@ let predefined_exceptions ~target =
         let v_name_js = Var.fresh () in
         let v_index = Var.fresh () in
         [ Let (v_name, Constant (String name)), noloc ]
-        @ (match target with
+        @ (match Config.target () with
           | `Wasm -> []
           | `JavaScript ->
               [ ( Let (v_name_js, Constant (NativeString (Native_string.of_string name)))
@@ -3184,14 +3167,14 @@ let predefined_exceptions ~target =
                     , [ Pc (Int (Int32.of_int index))
                       ; Pv exn
                       ; Pv
-                          (match target with
+                          (match Config.target () with
                           | `JavaScript -> v_name_js
                           | `Wasm -> v_name)
                       ] ) )
             , noloc )
           ]
         @
-        match target with
+        match Config.target () with
         | `JavaScript -> []
         | `Wasm ->
             [ ( Let
@@ -3213,7 +3196,7 @@ let predefined_exceptions ~target =
   in
   { start = 0; blocks = Addr.Map.singleton 0 block; free_pc = 1 }, unit_info
 
-let link_info ~target ~symbols ~primitives ~crcs =
+let link_info ~symbols ~primitives ~crcs =
   let gdata = Code.Var.fresh_n "global_data" in
   let symbols_array =
     Ocaml_compiler.Symtable.GlobalMap.fold
@@ -3231,8 +3214,8 @@ let link_info ~target ~symbols ~primitives ~crcs =
     (* Include linking information *)
     let sections = { symb = symbols; crcs; prim = primitives; dlpt = [] } in
     let infos =
-      [ "sections", Constants.parse ~target (Obj.repr sections)
-      ; "symbols", Constants.parse ~target (Obj.repr symbols_array)
+      [ "sections", Constants.parse (Obj.repr sections)
+      ; "symbols", Constants.parse (Obj.repr symbols_array)
       ; "prim_count", Int (Int32.of_int (List.length primitives))
       ]
     in
diff --git a/compiler/lib/parse_bytecode.mli b/compiler/lib/parse_bytecode.mli
index 33edf53f1c..dac8e266d9 100644
--- a/compiler/lib/parse_bytecode.mli
+++ b/compiler/lib/parse_bytecode.mli
@@ -52,8 +52,7 @@ end
 val read_primitives : Toc.t -> in_channel -> string list
 
 val from_exe :
-     target:[ `JavaScript | `Wasm ]
-  -> ?includes:string list
+     ?includes:string list
   -> linkall:bool
   -> link_info:bool
   -> include_cmis:bool
@@ -63,8 +62,7 @@ val from_exe :
   -> one
 
 val from_cmo :
-     target:[ `JavaScript | `Wasm ]
-  -> ?includes:string list
+     ?includes:string list
   -> ?include_cmis:bool
   -> ?debug:bool
   -> Cmo_format.compilation_unit
@@ -72,8 +70,7 @@ val from_cmo :
   -> one
 
 val from_cma :
-     target:[ `JavaScript | `Wasm ]
-  -> ?includes:string list
+     ?includes:string list
   -> ?include_cmis:bool
   -> ?debug:bool
   -> Cmo_format.library
@@ -90,11 +87,10 @@ val from_string :
   -> string
   -> Code.program * Debug.t
 
-val predefined_exceptions : target:[ `JavaScript | `Wasm ] -> Code.program * Unit_info.t
+val predefined_exceptions : Code.program * Unit_info.t
 
 val link_info :
-     target:[ `JavaScript | `Wasm ]
-  -> symbols:Ocaml_compiler.Symtable.GlobalMap.t
+     symbols:Ocaml_compiler.Symtable.GlobalMap.t
   -> primitives:StringSet.t
   -> crcs:(string * Digest.t option) list
   -> Code.program
diff --git a/compiler/lib/specialize_js.ml b/compiler/lib/specialize_js.ml
index 162b877582..e8fa7b9535 100644
--- a/compiler/lib/specialize_js.ml
+++ b/compiler/lib/specialize_js.ml
@@ -22,8 +22,8 @@ open! Stdlib
 open Code
 open Flow
 
-let specialize_instr info i =
-  match i, Config.target () with
+let specialize_instr ~target info i =
+  match i, target with
   | Let (x, Prim (Extern "caml_format_int", [ y; z ])), `JavaScript -> (
       match the_string_of info y with
       | Some "%d" -> (
@@ -156,7 +156,7 @@ let equal3 a b c = Code.Var.equal a b && Code.Var.equal b c
 
 let equal4 a b c d = Code.Var.equal a b && Code.Var.equal b c && Code.Var.equal c d
 
-let specialize_instrs info l =
+let specialize_instrs ~target info l =
   let rec aux info checks l acc =
     match l with
     | [] -> List.rev acc
@@ -285,22 +285,22 @@ let specialize_instrs info l =
               in
               aux info ((y, idx) :: checks) r acc
         | _ ->
-            let i = specialize_instr info i in
+            let i = specialize_instr ~target info i in
             aux info checks r ((i, loc) :: acc))
   in
   aux info [] l []
 
-let specialize_all_instrs info p =
+let specialize_all_instrs ~target info p =
   let blocks =
     Addr.Map.map
-      (fun block -> { block with Code.body = specialize_instrs info block.body })
+      (fun block -> { block with Code.body = specialize_instrs ~target info block.body })
       p.blocks
   in
   { p with blocks }
 
 (****)
 
-let f info p = specialize_all_instrs info p
+let f info p = specialize_all_instrs ~target:(Config.target ()) info p
 
 let f_once p =
   let rec loop acc l =