Make local.tee's type its local's type (#2511)

According to the current spec, `local.tee`'s return type should be the
same as its local's type. (Discussions on whether we should change this
rule is going on in WebAssembly/reference-types#55, but here I will
assume this spec does not change. If this changes, we should change many
parts of Binaryen transformation anyway...)

But currently in Binaryen `local.tee`'s type is computed from its
value's type. This didn't make any difference in the MVP, but after we
have subtype relationship in #2451, this can become a problem. For
example:
```
(func $test (result funcref) (local $0 anyref)
  (local.tee $0
    (ref.func $test)
  )
)
```
This shouldn't validate in the spec, but this will pass Binaryen
validation with the current `local.tee` implementation.

This makes `local.tee`'s type computed from the local's type, and makes
`LocalSet::makeTee` get a type parameter, to which we should pass the
its corresponding local's type. We don't embed the local type in the
class `LocalSet` because it may increase memory size.

This also fixes the type of `local.get` to be the local type where
`local.get` and `local.set` pair is created from `local.tee`.

1 files changed, 1 insertions, 1 deletions

diff --git a/test/binaryen.js/kitchen-sink.js b/test/binaryen.js/kitchen-sink.js
index 83e3d4a44..982bcc927 100644
--- a/test/binaryen.js/kitchen-sink.js
+++ b/test/binaryen.js/kitchen-sink.js
@@ -469,7 +469,7 @@ function test_core() {
     ),
     module.drop(module.local.get(0, Binaryen.i32)),
     module.local.set(0, makeInt32(101)),
-    module.drop(module.local.tee(0, makeInt32(102))),
+    module.drop(module.local.tee(0, makeInt32(102), Binaryen.i32)),
     module.i32.load(0, 0, makeInt32(1)),
     module.i64.load16_s(2, 1, makeInt32(8)),
     module.f32.load(0, 0, makeInt32(2)),