2 files changed, 26 insertions, 5 deletions

diff --git a/src/wasm/literal.cpp b/src/wasm/literal.cpp
index 34f3d250d..80ff47b17 100644
--- a/src/wasm/literal.cpp
+++ b/src/wasm/literal.cpp
@@ -71,7 +71,8 @@ Literal::Literal(const uint8_t init[16]) : type(Type::v128) {
 
 Literal::Literal(std::shared_ptr<GCData> gcData, HeapType type)
   : gcData(gcData), type(type, NonNullable) {
-  // The type must be a proper type for GC data.
+  // The type must be a proper type for GC data: either a struct, array, or
+  // string; or a null.
   assert((isData() && gcData) || (type.isBottom() && !gcData));
 }
 
@@ -577,7 +578,20 @@ std::ostream& operator<<(std::ostream& o, Literal literal) {
         case HeapType::struct_:
         case HeapType::array:
           WASM_UNREACHABLE("invalid type");
-        case HeapType::string:
+        case HeapType::string: {
+          auto data = literal.getGCData();
+          if (!data) {
+            o << "nullstring";
+          } else {
+            o << "string(\"";
+            for (auto c : data->values) {
+              // TODO: more than ascii
+              o << char(c.getInteger());
+            }
+            o << "\")";
+          }
+          break;
+        }
         case HeapType::stringview_wtf8:
         case HeapType::stringview_wtf16:
         case HeapType::stringview_iter:
diff --git a/src/wasm/wasm-type.cpp b/src/wasm/wasm-type.cpp
index 2c26f0e21..cebb1b489 100644
--- a/src/wasm/wasm-type.cpp
+++ b/src/wasm/wasm-type.cpp
@@ -897,7 +897,8 @@ bool Type::isFunction() const {
 
 bool Type::isData() const {
   if (isBasic()) {
-    return false;
+    // The only basic type that is considered data is a string.
+    return isString();
   } else {
     auto* info = getTypeInfo(*this);
     return info->isRef() && info->ref.heapType.isData();
@@ -924,6 +925,8 @@ bool Type::isStruct() const { return isRef() && getHeapType().isStruct(); }
 
 bool Type::isArray() const { return isRef() && getHeapType().isArray(); }
 
+bool Type::isString() const { return isRef() && getHeapType().isString(); }
+
 bool Type::isDefaultable() const {
   // A variable can get a default value if its type is concrete (unreachable
   // and none have no values, hence no default), and if it's a reference, it
@@ -1267,7 +1270,7 @@ bool HeapType::isFunction() const {
 
 bool HeapType::isData() const {
   if (isBasic()) {
-    return id == struct_ || id == array;
+    return id == struct_ || id == array || id == string;
   } else {
     return getHeapTypeInfo(*this)->isData();
   }
@@ -1297,6 +1300,8 @@ bool HeapType::isArray() const {
   }
 }
 
+bool HeapType::isString() const { return *this == HeapType::string; }
+
 bool HeapType::isBottom() const {
   if (isBasic()) {
     switch (getBasic()) {
@@ -1672,7 +1677,9 @@ bool SubTyper::isSubType(HeapType a, HeapType b) {
       case HeapType::any:
         return a.getBottom() == HeapType::none;
       case HeapType::eq:
-        return a == HeapType::i31 || a == HeapType::none || a.isData();
+        return a == HeapType::i31 || a == HeapType::none ||
+               a == HeapType::struct_ || a == HeapType::array || a.isStruct() ||
+               a.isArray();
       case HeapType::i31:
         return a == HeapType::none;
       case HeapType::struct_: