3 files changed, 8 insertions, 0 deletions
diff --git a/src/ir/ReFinalize.cpp b/src/ir/ReFinalize.cpp
index 785b36c80..b8d620560 100644
--- a/src/ir/ReFinalize.cpp
+++ b/src/ir/ReFinalize.cpp
@@ -163,6 +163,7 @@ void ReFinalize::visitArrayNew(ArrayNew* curr) { curr->finalize(); }
 void ReFinalize::visitArrayGet(ArrayGet* curr) { curr->finalize(); }
 void ReFinalize::visitArraySet(ArraySet* curr) { curr->finalize(); }
 void ReFinalize::visitArrayLen(ArrayLen* curr) { curr->finalize(); }
+void ReFinalize::visitRefAs(RefAs* curr) { curr->finalize(); }
 
 void ReFinalize::visitFunction(Function* curr) {
   // we may have changed the body from unreachable to none, which might be bad
diff --git a/src/ir/cost.h b/src/ir/cost.h
index 95c483601..8c23c91f8 100644
--- a/src/ir/cost.h
+++ b/src/ir/cost.h
@@ -623,6 +623,7 @@ struct CostAnalyzer : public OverriddenVisitor<CostAnalyzer, Index> {
   Index visitArrayLen(ArrayLen* curr) {
     return 1 + nullCheckCost(curr->ref) + visit(curr->ref);
   }
+  Index visitRefAs(RefAs* curr) { return 1 + visit(curr->value); }
 
 private:
   Index nullCheckCost(Expression* ref) {
diff --git a/src/ir/effects.h b/src/ir/effects.h
index 603ed49a3..ca440ce51 100644
--- a/src/ir/effects.h
+++ b/src/ir/effects.h
@@ -598,6 +598,12 @@ private:
         parent.implicitTrap = true;
       }
     }
+    void visitRefAs(RefAs* curr) {
+      // traps when the arg is not valid
+      if (curr->value->type.isNullable()) {
+        parent.implicitTrap = true;
+      }
+    }
   };
 
 public: