Flag to generate the new exception handling instructions

Author: vouillon

.github/workflows/wasm_of_ocaml.yml

@@ -228,7 +228,7 @@ jobs:
         working-directory: ./wasm_of_ocaml
         env:
           WASM_ENGINE: wasmtime
-          WASI_FLAGS: --enable trap-on-exception
+          WASI_FLAGS: --enable exnref
           RUST_BACKTRACE: 0
         continue-on-error: true
         run: opam exec -- dune build @runtest-wasm --profile wasi

compiler/lib-wasm/binaryen.ml

@@ -136,12 +136,12 @@ let optimize
     ~output_file
     () =
   command
-    ("wasm-opt"
-     :: (common_options ()
-        @ (if Config.Flag.trap_on_exception () then [] else [ "--traps-never-happen" ])
-        @ (match options with
-          | Some o -> o
-          | None -> optimization_options profile)
-        @ [ Filename.quote input_file; "-o"; Filename.quote output_file ])
+    (("wasm-opt" :: (if Config.Flag.exnref () then [ "--emit-exnref" ] else []))
+    @ (common_options ()
+      @ (if Config.Flag.trap_on_exception () then [] else [ "--traps-never-happen" ])
+      @ (match options with
+        | Some o -> o
+        | None -> optimization_options profile)
+      @ [ Filename.quote input_file; "-o"; Filename.quote output_file ])
     @ opt_flag "--input-source-map" opt_input_sourcemap
     @ opt_flag "--output-source-map" opt_output_sourcemap)

compiler/lib/config.ml

@@ -109,6 +109,8 @@ module Flag = struct
 
   let wasi = o ~name:"wasi" ~default:false
 
+  let exnref = o ~name:"exnref" ~default:false
+
   let trap_on_exception = o ~name:"trap-on-exception" ~default:false
 end
 

compiler/lib/config.mli

@@ -78,6 +78,8 @@ module Flag : sig
 
   val wasi : unit -> bool
 
+  val exnref : unit -> bool
+
   val trap_on_exception : unit -> bool
 
   val enable : string -> unit