[TypedFunctionReferences] Identify subtyping between funcref and all typed function references (#3357)

1 files changed, 15 insertions, 2 deletions

diff --git a/src/wasm/wasm-type.cpp b/src/wasm/wasm-type.cpp
index cf68d92e9..f98077961 100644
--- a/src/wasm/wasm-type.cpp
+++ b/src/wasm/wasm-type.cpp
@@ -521,8 +521,21 @@ bool Type::isSubType(Type left, Type right) {
     return true;
   }
   if (left.isRef() && right.isRef()) {
-    return right == Type::anyref ||
-           (left == Type::i31ref && right == Type::eqref);
+    // Everything is a subtype of anyref.
+    if (right == Type::anyref) {
+      return true;
+    }
+    // Various things are subtypes of eqref.
+    if ((left == Type::i31ref || left.getHeapType().isArray() ||
+         left.getHeapType().isStruct()) &&
+        right == Type::eqref) {
+      return true;
+    }
+    // All typed function signatures are subtypes of funcref.
+    if (left.getHeapType().isSignature() && right == Type::funcref) {
+      return true;
+    }
+    return false;
   }
   if (left.isTuple() && right.isTuple()) {
     if (left.size() != right.size()) {