1 files changed, 9 insertions, 0 deletions
diff --git a/js/src/frontend/SharedContext.h b/js/src/frontend/SharedContext.h
index 12f9a6ed12..ab0606527e 100644
--- a/js/src/frontend/SharedContext.h
+++ b/js/src/frontend/SharedContext.h
@@ -180,6 +180,10 @@ class SharedContext {
   // FunctionBox::copyUpdated* methods.
   bool isScriptExtraFieldCopiedToStencil : 1;
 
+  // Indicates this shared context is eligible to use JSOp::ArgumentsLength
+  // when emitting the ArgumentsLength parse node.
+  bool eligibleForArgumentsLength : 1;
+
   // End of fields.
 
   enum class Kind : uint8_t { FunctionBox, Global, Eval, Module };
@@ -273,6 +277,11 @@ class SharedContext {
     return retVal;
   }
 
+  bool isEligibleForArgumentsLength() {
+    return eligibleForArgumentsLength && !bindingsAccessedDynamically();
+  }
+  void setIneligibleForArgumentsLength() { eligibleForArgumentsLength = false; }
+
   void copyScriptExtraFields(ScriptStencilExtra& scriptExtra);
 };