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  1. JDK
  2. JDK-8233081

C1: PatchingStub for field access copies too much

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      Description

        C1's PatchingStub copies bytes from the method's regular code area to a dedicated patching template which gets copied back when the patching work is completed.
        Currently, C1's PatchingStub with PatchID "access_field_id" copies all bytes between the PatchingStub's instanciation and the patching_epilog call.
        This is not only more than necessary, it can cause _bytes_to_copy to exceed its one byte limitation: emit_int8(_bytes_to_copy).
        On some platforms, code for VerifyOops is part of the code which gets copied forth and back. This is unnecessary and should be avoided.
        Note that the template for PatchID "access_field_id" never gets executed, so there's no reason for copying more than the code to be patched.

        So there are basically 2 issues:
        - Possible size overflow (depending on platform and activated features)
        - Wasted code cache space

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            backported by

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8233991 C1: PatchingStub for field access copies too much

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8234578 C1: PatchingStub for field access copies too much

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved

            Backport - A issue that is required to port a Bug or Feature into another product release. This issue type is generally associated with the main Bug/Feature to represent each individual release of the port. JDK-8246139 C1: PatchingStub for field access copies too much

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved
            relates to

            Bug - A problem which impairs or prevents the functions of the product. JDK-8234645 ARM32: C1: PatchingStub for field access: not enough bytes

            • P2 - Crashes, loss of data, severe memory leak.
            • Resolved

            Bug - A problem which impairs or prevents the functions of the product. JDK-8231757 [ppc] Fix VerifyOops. Errors show since 8231058.

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved

            Bug - A problem which impairs or prevents the functions of the product. JDK-8260502 [s390] NativeMovRegMem::verify() fails because it's too strict

            • P4 - Minor loss of function, or other problem where easy workaround is present.
            • Resolved

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                mdoerr Martin Doerr
                mdoerr Martin Doerr
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