4 files changed, 22 insertions, 9 deletions
diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 0160ffaf6..386f89060 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -6893,11 +6893,14 @@ bool WasmBinaryBuilder::maybeVisitI31Get(Expression*& out, uint32_t code) {
 }
 
 bool WasmBinaryBuilder::maybeVisitRefTest(Expression*& out, uint32_t code) {
-  if (code == BinaryConsts::RefTestStatic || code == BinaryConsts::RefTest) {
+  if (code == BinaryConsts::RefTestStatic || code == BinaryConsts::RefTest ||
+      code == BinaryConsts::RefTestNull) {
     bool legacy = code == BinaryConsts::RefTestStatic;
-    auto intendedType = legacy ? getIndexedHeapType() : getHeapType();
+    auto castType = legacy ? getIndexedHeapType() : getHeapType();
+    auto nullability =
+      (code == BinaryConsts::RefTestNull) ? Nullable : NonNullable;
     auto* ref = popNonVoidExpression();
-    out = Builder(wasm).makeRefTest(ref, intendedType);
+    out = Builder(wasm).makeRefTest(ref, Type(castType, nullability));
     return true;
   }
   return false;
diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index cf287d8a1..4fdc29a66 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -2776,9 +2776,15 @@ Expression* SExpressionWasmBuilder::makeI31Get(Element& s, bool signed_) {
 }
 
 Expression* SExpressionWasmBuilder::makeRefTest(Element& s) {
-  auto heapType = parseHeapType(*s[1]);
-  auto* ref = parseExpression(*s[2]);
-  return Builder(wasm).makeRefTest(ref, heapType);
+  int i = 1;
+  auto nullability = NonNullable;
+  if (s[0]->str().str != "ref.test_static" && s[1]->str().str == "null") {
+    nullability = Nullable;
+    ++i;
+  }
+  auto heapType = parseHeapType(*s[i++]);
+  auto* ref = parseExpression(*s[i++]);
+  return Builder(wasm).makeRefTest(ref, Type(heapType, nullability));
 }
 
 Expression* SExpressionWasmBuilder::makeRefCast(Element& s) {
diff --git a/src/wasm/wasm-stack.cpp b/src/wasm/wasm-stack.cpp
index 911447b48..e24060f2a 100644
--- a/src/wasm/wasm-stack.cpp
+++ b/src/wasm/wasm-stack.cpp
@@ -2025,8 +2025,12 @@ void BinaryInstWriter::visitCallRef(CallRef* curr) {
 
 void BinaryInstWriter::visitRefTest(RefTest* curr) {
   o << int8_t(BinaryConsts::GCPrefix);
-  o << U32LEB(BinaryConsts::RefTest);
-  parent.writeHeapType(curr->intendedType);
+  if (curr->castType.isNullable()) {
+    o << U32LEB(BinaryConsts::RefTestNull);
+  } else {
+    o << U32LEB(BinaryConsts::RefTest);
+  }
+  parent.writeHeapType(curr->castType.getHeapType());
 }
 
 void BinaryInstWriter::visitRefCast(RefCast* curr) {
diff --git a/src/wasm/wasm-validator.cpp b/src/wasm/wasm-validator.cpp
index b102ecb1c..68fb58ec4 100644
--- a/src/wasm/wasm-validator.cpp
+++ b/src/wasm/wasm-validator.cpp
@@ -2513,7 +2513,7 @@ void FunctionValidator::visitRefTest(RefTest* curr) {
     return;
   }
   shouldBeEqual(
-    curr->intendedType.getBottom(),
+    curr->castType.getHeapType().getBottom(),
     curr->ref->type.getHeapType().getBottom(),
     curr,
     "ref.test target type and ref type must have a common supertype");