Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-8038416

Access to undefined scoped variables deoptimized too much

    XMLWordPrintable

Details

    • Bug
    • Resolution: Fixed
    • P4
    • 9
    • 9
    • core-libs
    • None
    • b17
    • generic
    • generic

    Backports

      Description

        JDK-8038396 deoptimizes access to scoped variables that start out as undefined too much.
        E.g.

        var x = foo()
        var a = 3;
        a++; // becomes double instead of optimistic int

        function foo() { return null };

        The reason is that the first deoptimizing recompilation happens when "foo()" is invoked and the return value doesn't fit in an int. At this time, "a" is not yet initialized, so naively observing Undefined value turns its subsequent accessor into Object one. The fix is to avoid inferring expression types for undefined scoped variables (those for which Property.getCurrentType() == null), instead of presuming Object.

        Attachments

          Issue Links

            Activity

              People

                attila Attila Szegedi
                attila Attila Szegedi
                Votes:
                0 Vote for this issue
                Watchers:
                2 Start watching this issue

                Dates

                  Created:
                  Updated:
                  Resolved: