3 files changed, 17 insertions, 4 deletions
diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 60a4bad77..9cd7e79a7 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -6712,10 +6712,13 @@ bool WasmBinaryBuilder::maybeVisitRefCast(Expression*& out, uint32_t code) {
     auto* ref = popNonVoidExpression();
     out = Builder(wasm).makeRefCast(ref, rtt);
     return true;
-  } else if (code == BinaryConsts::RefCastStatic) {
+  } else if (code == BinaryConsts::RefCastStatic ||
+             code == BinaryConsts::RefCastNopStatic) {
     auto intendedType = getIndexedHeapType();
     auto* ref = popNonVoidExpression();
-    out = Builder(wasm).makeRefCast(ref, intendedType);
+    auto safety =
+      code == BinaryConsts::RefCastNopStatic ? RefCast::Unsafe : RefCast::Safe;
+    out = Builder(wasm).makeRefCast(ref, intendedType, safety);
     return true;
   }
   return false;
diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index 02da4f909..8680ff8cc 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -2702,7 +2702,13 @@ Expression* SExpressionWasmBuilder::makeRefCast(Element& s) {
 Expression* SExpressionWasmBuilder::makeRefCastStatic(Element& s) {
   auto heapType = parseHeapType(*s[1]);
   auto* ref = parseExpression(*s[2]);
-  return Builder(wasm).makeRefCast(ref, heapType);
+  return Builder(wasm).makeRefCast(ref, heapType, RefCast::Safe);
+}
+
+Expression* SExpressionWasmBuilder::makeRefCastNopStatic(Element& s) {
+  auto heapType = parseHeapType(*s[1]);
+  auto* ref = parseExpression(*s[2]);
+  return Builder(wasm).makeRefCast(ref, heapType, RefCast::Unsafe);
 }
 
 Expression* SExpressionWasmBuilder::makeBrOn(Element& s, BrOnOp op) {
diff --git a/src/wasm/wasm-stack.cpp b/src/wasm/wasm-stack.cpp
index 8afeb6779..8588a049f 100644
--- a/src/wasm/wasm-stack.cpp
+++ b/src/wasm/wasm-stack.cpp
@@ -2051,7 +2051,11 @@ void BinaryInstWriter::visitRefCast(RefCast* curr) {
   if (curr->rtt) {
     o << U32LEB(BinaryConsts::RefCast);
   } else {
-    o << U32LEB(BinaryConsts::RefCastStatic);
+    if (curr->safety == RefCast::Unsafe) {
+      o << U32LEB(BinaryConsts::RefCastNopStatic);
+    } else {
+      o << U32LEB(BinaryConsts::RefCastStatic);
+    }
     parent.writeIndexedHeapType(curr->intendedType);
   }
 }