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diff --git a/src/ast/properties.h b/src/ast/properties.h
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+/*
+ * Copyright 2016 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef wasm_ast_properties_h
+#define wasm_ast_properties_h
+
+#include "wasm.h"
+
+namespace wasm {
+
+struct Properties {
+  static bool emitsBoolean(Expression* curr) {
+    if (auto* unary = curr->dynCast<Unary>()) {
+      return unary->isRelational();
+    } else if (auto* binary = curr->dynCast<Binary>()) {
+      return binary->isRelational();
+    }
+    return false;
+  }
+
+  static bool isSymmetric(Binary* binary) {
+    switch (binary->op) {
+      case AddInt32:
+      case MulInt32: 
+      case AndInt32:
+      case OrInt32:
+      case XorInt32:
+      case EqInt32:
+      case NeInt32:
+
+      case AddInt64:
+      case MulInt64: 
+      case AndInt64:
+      case OrInt64:
+      case XorInt64:
+      case EqInt64:
+      case NeInt64: return true;
+
+      default: return false;
+    }
+  }
+};
+
+} // wasm
+
+#endif // wams_ast_properties_h
+