JDK-6991197 : G1: specialize deal_with_reference() for narrowOop*
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: gc
  • Affected Version: hs20
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2010-10-12
  • Updated: 2014-07-29
  • Resolved: 2014-01-31
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8u20Fixed 9 b04Fixed
G1ParScanThreadState::deal_with_reference(T*) should be specialized for narrowOop*; doing so may help performance when compressed oops are enabled.

EVALUATION deal_with_reference(T*) first checks whether the partial array mask bit is set and branches accordingly. This check is unnecessary when T is narrowOop, so the test and branch can be eliminated for narrowOop* (presumably the most common type processed) if the method is specialized.