[Wasm GC] Add missing unreachable check in evaluateKindCheck (#5410)

2 files changed, 24 insertions, 1 deletions

diff --git a/src/ir/gc-type-utils.h b/src/ir/gc-type-utils.h
index 8832d4d0f..1646e47c3 100644
--- a/src/ir/gc-type-utils.h
+++ b/src/ir/gc-type-utils.h
@@ -123,7 +123,9 @@ inline EvaluationResult evaluateKindCheck(Expression* curr) {
 
   Kind actual;
 
-  if (childType.isFunction()) {
+  if (childType == Type::unreachable) {
+    return Unknown;
+  } else if (childType.isFunction()) {
     actual = Func;
   } else if (childType.isData()) {
     actual = Data;
diff --git a/test/lit/passes/optimize-instructions-gc.wast b/test/lit/passes/optimize-instructions-gc.wast
index abf3da432..c5100434d 100644
--- a/test/lit/passes/optimize-instructions-gc.wast
+++ b/test/lit/passes/optimize-instructions-gc.wast
@@ -3230,4 +3230,25 @@
       )
     )
   )
+
+  ;; CHECK:      (func $as_of_unreachable (type $none_=>_ref|data|) (result (ref data))
+  ;; CHECK-NEXT:  (ref.as_data
+  ;; CHECK-NEXT:   (unreachable)
+  ;; CHECK-NEXT:  )
+  ;; CHECK-NEXT: )
+  ;; NOMNL:      (func $as_of_unreachable (type $none_=>_ref|data|) (result (ref data))
+  ;; NOMNL-NEXT:  (ref.as_data
+  ;; NOMNL-NEXT:   (unreachable)
+  ;; NOMNL-NEXT:  )
+  ;; NOMNL-NEXT: )
+  (func $as_of_unreachable (result (ref data))
+    ;; The cast will definitely fail, so we can turn it into an unreachable. The
+    ;; ref.as must then ignore the unreachable input and not error on trying to
+    ;; infer anything about it.
+    (ref.as_data
+      (ref.cast $A
+        (ref.null none)
+      )
+    )
+  )
 )