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  1. JDK
  2. JDK-8280872

Reorder code cache segments to improve code density

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    • b17
    • aarch64

    Backports

      Description

        To reduce far jumps, far calls and trampolines in segmented CodeCache of the size [128M, 248M) and equally sized profiled and non-profiled segments, we can put the non-nmethod segment in between the profiled and non-profiled segments.
        Doing this we will have the sizes of the combined segments (non-nmethod, profiled) and (non-nmethod, non-profiled) below 128M. So there is no need for far jumps, far calls and trampolines to the non-nmethod section. Also when we reposition the non-nmethod segment, in the segment on the left we can allocate space from the end to make everything close to each other.

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            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-8295147 Reorder code cache segments to improve code density

            • 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-8295556 Reorder code cache segments to improve code density

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

            Enhancement - null JDK-8283102 AArch64: Optimize BR+FAR_JUMP into one BR in MachUEPNode::emit

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

            Bug - A problem which impairs or prevents the functions of the product. JDK-8284681 compiler/c2/aarch64/TestFarJump.java fails with "RuntimeException: for CodeHeap < 250MB the far jump is expected to be encoded with a single branch instruction"

            • P3 - Major loss of function.
            • Resolved
            links to

            Commit Commit openjdk/jdk17u-dev/d4d2e34a

            Commit Commit openjdk/jdk/e524107a

            Review Review openjdk/jdk17u-dev/743

            Review Review openjdk/jdk/7517

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                bulasevich Boris Ulasevich
                eastigeevich Evgeny Astigeevich
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                  Updated:
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