wasm2c exception handling is broken

[SoniEx2]

;;; TOOL: run-spec-wasm2c
;;; ARGS*: --enable-exceptions
(module
  (tag $e0)
  (func $throw (throw $e0))
  (func (export "break-throw") (result i32)
    (try $outer (result i32)
      (do
        (try (result i32)
          (do
            (block $a
              (try (do (br $a)) (delegate $outer))
            )
            (call $throw)
            (i32.const 0)
          )
          (catch $e0 (i32.const 1))
        )
      )
      (catch $e0 (i32.const 2))
    )
  )
)

(assert_return (invoke "break-throw") (i32.const 1))
(;; STDOUT ;;;
1/1 tests passed.
;;; STDOUT ;;)

[SoniEx2]

this works correctly tho:

;;; TOOL: run-spec-wasm2c
;;; ARGS*: --enable-exceptions
(module
  (tag $e0)
  (func $throw (throw $e0))
  (func (export "break-throw") (result i32)
    (try $outer (result i32)
      (do
        (try (result i32)
          (do
            (block $a (result i32)
              (try (do (br $a (i32.const 0))) (delegate $outer)) (i32.const 0)
            ) (drop)
            (call $throw)
            (i32.const 0)
          )
          (catch $e0 (i32.const 1))
        )
      )
      (catch $e0 (i32.const 2))
    )
  )
)

(assert_return (invoke "break-throw") (i32.const 1))
(;; STDOUT ;;;
1/1 tests passed.
;;; STDOUT ;;)

[keithw]

Thanks -- could you please contribute the test upstream (could reference WebAssembly/exception-handling#210) and then we'll pull it from there and adjust wasm2c to match? Would be good to make sure every implementation agrees on the semantics.

[SoniEx2]

this also seems to work correctly:

;;; TOOL: run-spec-wasm2c
;;; ARGS*: --enable-exceptions
(module
  (tag $e0)
  (func $throw (throw $e0))
  (func (export "break-throw") (result i32)
    (try $outer (result i32)
      (do
        (try (result i32)
          (do
            (block $a
              (try (do (br $a)) (delegate $outer))
            )
            (throw $e0)
            (i32.const 0)
          )
          (catch $e0 (i32.const 1))
        )
      )
      (catch $e0 (i32.const 2))
    )
  )
)

(assert_return (invoke "break-throw") (i32.const 1))
(;; STDOUT ;;;
1/1 tests passed.
;;; STDOUT ;;)