4 files changed, 76 insertions, 0 deletions

diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index fc14510e9..020953c1b 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -3052,6 +3052,12 @@ BinaryConsts::ASTNodes WasmBinaryBuilder::readExpression(Expression*& curr) {
         visitRefIs((curr = allocator.alloc<RefIs>())->cast<RefIs>(), opcode);
         break;
       }
+      if (opcode == BinaryConsts::RefAsFunc ||
+          opcode == BinaryConsts::RefAsData ||
+          opcode == BinaryConsts::RefAsI31) {
+        visitRefAs((curr = allocator.alloc<RefAs>())->cast<RefAs>(), opcode);
+        break;
+      }
       throwError("invalid code after GC prefix: " + std::to_string(opcode));
       break;
     }
@@ -5971,6 +5977,25 @@ bool WasmBinaryBuilder::maybeVisitArrayLen(Expression*& out, uint32_t code) {
   return true;
 }
 
+void WasmBinaryBuilder::visitRefAs(RefAs* curr, uint8_t code) {
+  BYN_TRACE("zz node: RefAs\n");
+  switch (code) {
+    case BinaryConsts::RefAsFunc:
+      curr->op = RefAsFunc;
+      break;
+    case BinaryConsts::RefAsData:
+      curr->op = RefAsData;
+      break;
+    case BinaryConsts::RefAsI31:
+      curr->op = RefAsI31;
+      break;
+    default:
+      WASM_UNREACHABLE("invalid code for ref.as_*");
+  }
+  curr->value = popNonVoidExpression();
+  curr->finalize();
+}
+
 void WasmBinaryBuilder::throwError(std::string text) {
   throw ParseException(text, 0, pos);
 }
diff --git a/src/wasm/wasm-s-parser.cpp b/src/wasm/wasm-s-parser.cpp
index b9927cbc7..5dec22eb3 100644
--- a/src/wasm/wasm-s-parser.cpp
+++ b/src/wasm/wasm-s-parser.cpp
@@ -2236,6 +2236,10 @@ Expression* SExpressionWasmBuilder::makeArrayLen(Element& s) {
   return Builder(wasm).makeArrayLen(ref);
 }
 
+Expression* SExpressionWasmBuilder::makeRefAs(Element& s, RefAsOp op) {
+  return Builder(wasm).makeRefAs(op, parseExpression(s[1]));
+}
+
 // converts an s-expression string representing binary data into an output
 // sequence of raw bytes this appends to data, which may already contain
 // content.
diff --git a/src/wasm/wasm-stack.cpp b/src/wasm/wasm-stack.cpp
index 5609dbb0e..197581e33 100644
--- a/src/wasm/wasm-stack.cpp
+++ b/src/wasm/wasm-stack.cpp
@@ -2072,6 +2072,22 @@ void BinaryInstWriter::visitArrayLen(ArrayLen* curr) {
   parent.writeHeapType(curr->ref->type.getHeapType());
 }
 
+void BinaryInstWriter::visitRefAs(RefAs* curr) {
+  switch (curr->op) {
+    case RefAsFunc:
+      o << int8_t(BinaryConsts::GCPrefix) << int8_t(BinaryConsts::RefAsFunc);
+      break;
+    case RefAsData:
+      o << int8_t(BinaryConsts::GCPrefix) << int8_t(BinaryConsts::RefAsData);
+      break;
+    case RefAsI31:
+      o << int8_t(BinaryConsts::GCPrefix) << int8_t(BinaryConsts::RefAsI31);
+      break;
+    default:
+      WASM_UNREACHABLE("invalid ref.as_*");
+  }
+}
+
 void BinaryInstWriter::emitScopeEnd(Expression* curr) {
   assert(!breakStack.empty());
   breakStack.pop_back();
diff --git a/src/wasm/wasm.cpp b/src/wasm/wasm.cpp
index cd1fb716c..2921f4974 100644
--- a/src/wasm/wasm.cpp
+++ b/src/wasm/wasm.cpp
@@ -245,6 +245,17 @@ const char* getExpressionName(Expression* curr) {
       return "array.set";
     case Expression::Id::ArrayLenId:
       return "array.len";
+    case Expression::Id::RefAsId:
+      switch (curr->cast<RefAs>()->op) {
+        case RefAsFunc:
+          return "ref.as_func";
+        case RefAsData:
+          return "ref.as_data";
+        case RefAsI31:
+          return "ref.as_i31";
+        default:
+          WASM_UNREACHABLE("unimplemented ref.is_*");
+      }
     case Expression::Id::NumExpressionIds:
       WASM_UNREACHABLE("invalid expr id");
   }
@@ -1153,6 +1164,26 @@ void ArrayLen::finalize() {
   }
 }
 
+void RefAs::finalize() {
+  if (value->type == Type::unreachable) {
+    type = Type::unreachable;
+    return;
+  }
+  switch (op) {
+    case RefAsFunc:
+      type = Type::funcref;
+      break;
+    case RefAsData:
+      type = Type::dataref;
+      break;
+    case RefAsI31:
+      type = Type::i31ref;
+      break;
+    default:
+      WASM_UNREACHABLE("unimplemented ref.is_*");
+  }
+}
+
 size_t Function::getNumParams() { return sig.params.size(); }
 
 size_t Function::getNumVars() { return vars.size(); }