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  1. JDK
  2. JDK-8308869

C2: use profile data in subtype checks when profile has more than one class

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Details

    • Enhancement
    • Resolution: Fixed
    • P4
    • 22
    • 21
    • hotspot
    • b15

    Description

      At subtype checks, we use profile data if both:

      1- and the test hasn't failed before
      2- if it reports a unique class

      If neither 1- nor 2- is true, then we ignore profile data. It seems unfortunate as if 1- is false, there's still a good chance the class reported by profile data is the common case and testing for it before going to the full blown subtype check would be faster overall. Even if 2- is false, but only 2 classes are ever seen at the subtype check, it's likely that emitting 1 comparison with each before the full blown subtype check is faster overall.

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          relates to

          Bug - A problem which impairs or prevents the functions of the product. JDK-8320296 [lworld] Fix profiling at array store subtype checks in Valhalla

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

          Enhancement - null JDK-8320404 Double whitespace in SubTypeCheckNode::dump_spec output

          • P5 - Cosmetic problem like misspelt words or misaligned text.
          • Resolved

          Enhancement - null JDK-8315763 Update subtype check profile collection on 32-bit ARM following 8308869

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

          Enhancement - null JDK-8315750 Update subtype check profile collection on PPC following 8308869

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

          Enhancement - null JDK-8315762 Update subtype check profile collection on s390x following 8308869

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

          Commit Commit openjdk/jdk/dac17279

          Review Review openjdk/jdk/14375

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              roland Roland Westrelin
              roland Roland Westrelin
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                Updated:
                Resolved: