[EH][GC] Send a non-nullable exnref from TryTable (#7013)

When EH+GC are enabled then wasm has non-nullable types, and the
sent exnref should be non-nullable. In BinaryenIR we use the non-
nullable type all the time, which we also do for function references
and other things; we lower it if GC is not enabled to a nullable type
for the binary format (see `WasmBinaryWriter::writeType`, to which
comments were added in this PR). That is, this PR makes us handle
exnref the same as those other types.

A new test verifies that behavior. Various existing tests are updated
because ReFinalize will now use the more refined type, so this is
an optimization. It is also a bugfix as in #6987 we started to emit
the refined form in the fuzzer, and this PR makes us handle it
properly in validation and ReFinalization.

1 files changed, 1 insertions, 1 deletions

diff --git a/test/lit/passes/merge-blocks-eh.wast b/test/lit/passes/merge-blocks-eh.wast
index e53f601fd..e56f536f4 100644
--- a/test/lit/passes/merge-blocks-eh.wast
+++ b/test/lit/passes/merge-blocks-eh.wast
@@ -100,7 +100,7 @@
 
   ;; CHECK:      (func $drop-block-try_catch_multi_partial (type $0)
   ;; CHECK-NEXT:  (tuple.drop 2
-  ;; CHECK-NEXT:   (block $outer (type $1) (result i32 exnref)
+  ;; CHECK-NEXT:   (block $outer (type $2) (result i32 (ref exn))
   ;; CHECK-NEXT:    (block $inner
   ;; CHECK-NEXT:     (try_table (catch_ref $i32 $outer) (catch_all $inner)
   ;; CHECK-NEXT:      (call $import)