[EH] Improve catch validation (#4315)

This improves validation of `catch` bodies mostly by checking the
validity of `pop`s.

For every `catch` body:
- Checks if its tag exists
- If the tag's type is none:
  - Ensures there shouldn't be any `pop`s
- If the tag's type is not none:
  - Checks if there's a single `pop` within the catch body
  - Checks if the tag type matches the `pop`'s type
  - Checks if the `pop`'s location is valid

For every `catch_all` body:
- Ensures there shuldn't be any `pop`s

This uncovers several bugs related to `pop`s in existing tests, which
this PR also fixes.

1 files changed, 28 insertions, 0 deletions

diff --git a/test/exception-handling.wast.from-wast b/test/exception-handling.wast.from-wast
index 1ce7a84b7..ee409652b 100644
--- a/test/exception-handling.wast.from-wast
+++ b/test/exception-handling.wast.from-wast
@@ -3,9 +3,11 @@
  (type $i32_=>_none (func (param i32)))
  (type $i64_=>_none (func (param i64)))
  (type $i32_i64_=>_none (func (param i32 i64)))
+ (type $anyref_=>_none (func (param anyref)))
  (tag $e-i32 (param i32))
  (tag $e-i64 (param i64))
  (tag $e-i32-i64 (param i32 i64))
+ (tag $e-anyref (param anyref))
  (tag $e-empty (param))
  (func $foo
   (nop)
@@ -351,4 +353,30 @@
    )
   )
  )
+ (func $pop_test
+  (try $try
+   (do
+    (nop)
+   )
+   (catch $e-i32
+    (throw $e-i32
+     (if (result i32)
+      (pop i32)
+      (i32.const 0)
+      (i32.const 3)
+     )
+    )
+   )
+  )
+  (try $try28
+   (do
+    (nop)
+   )
+   (catch $e-anyref
+    (drop
+     (pop funcref)
+    )
+   )
+  )
+ )
 )