1 files changed, 50 insertions, 0 deletions
diff --git a/js/src/vm/TypeofEqOperand.h b/js/src/vm/TypeofEqOperand.h
new file mode 100644
index 0000000000..b3236baed6
--- /dev/null
+++ b/js/src/vm/TypeofEqOperand.h
@@ -0,0 +1,50 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef vm_TypeofEqOperand_h
+#define vm_TypeofEqOperand_h
+
+#include "mozilla/Assertions.h"  // MOZ_ASSERT
+
+#include <stdint.h>  // uint8_t
+
+#include "jspubtd.h"     // JSType
+#include "vm/Opcodes.h"  // JSOp
+
+namespace js {
+
+struct TypeofEqOperand {
+  static constexpr uint8_t TYPE_MASK = 0x0f;
+  static constexpr uint8_t NEQ_BIT = 0x80;
+
+ private:
+  uint8_t value;
+
+  static uint8_t toNeqBit(JSOp compareOp) {
+    MOZ_ASSERT(compareOp == JSOp::Eq || compareOp == JSOp::Ne);
+    return compareOp == JSOp::Ne ? NEQ_BIT : 0;
+  }
+
+  explicit TypeofEqOperand(uint8_t value) : value(value) {}
+
+ public:
+  TypeofEqOperand(JSType type, JSOp compareOp)
+      : value(type | toNeqBit(compareOp)) {}
+
+  static TypeofEqOperand fromRawValue(uint8_t value) {
+    return TypeofEqOperand(value);
+  }
+
+  JSType type() const { return JSType(value & TYPE_MASK); }
+  JSOp compareOp() const { return (value & NEQ_BIT) ? JSOp::Ne : JSOp::Eq; }
+  uint8_t rawValue() const { return value; }
+};
+
+static_assert((JSTYPE_LIMIT & TypeofEqOperand::TYPE_MASK) == JSTYPE_LIMIT);
+
+}  // namespace js
+
+#endif  // vm_TypeofEqOperand_h