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  1. JDK
  2. JDK-8251322

Improve BitMap::iterate

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Details

    • Enhancement
    • Resolution: Fixed
    • P4
    • 16
    • 16
    • hotspot
    • None
    • b11

    Description

      BitMap::iterate could be improved by using count_trailing_zeros instead of looping over the individual bits in a word, much as was done for get_next_one_offset and friends by JDK-6735527. Rewriting it to use get_next_one_offset would likely both simplify it and make it faster.

      It used to be that the deprecated (and now removed) CMS GC was the only user of this function, so improving it wasn't a priority. But it's now being used by CDS (see JDK-8208658, for example), so may be worthwhile now.

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        Issue Links

          relates to

          Enhancement - null JDK-8251330 Reorder CDS archived heap to speed up relocation

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

          Enhancement - null JDK-6735527 Bitmap - speed up searches

          • P3 - Major loss of function.
          • Resolved

          Enhancement - null JDK-8208658 Make CDS archived heap regions usable even if compressed oop encoding has changed

          • P3 - Major loss of function.
          • Resolved

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              kbarrett Kim Barrett
              kbarrett Kim Barrett
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              Dates

                Created:
                Updated:
                Resolved: