JDK-7132690 : InstanceKlass::_reference_type should be u1 type
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: runtime
  • Affected Version: 8
  • Priority: P4
  • Status: Closed
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2012-01-24
  • Updated: 2012-10-13
  • Resolved: 2012-02-11
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JDK 7 JDK 8 Other
7u4Fixed 8Fixed hs23Fixed
The ReferenceType is defined as an enum with 6 values (src/share/vm/utilities/globalDefinitions.hpp). The InstanceKlass::_reference_type is an int type. It can be reduced to u1 type. Move the field within InstanceKlass to utilize unused memory can save 4-byte for each class.

EVALUATION http://hg.openjdk.java.net/lambda/lambda/hotspot/rev/a79cb7c55012

EVALUATION http://hg.openjdk.java.net/hsx/hotspot-gc/hotspot/rev/a79cb7c55012

EVALUATION http://hg.openjdk.java.net/hsx/hotspot-comp/hotspot/rev/a79cb7c55012

EVALUATION http://hg.openjdk.java.net/hsx/hotspot-emb/hotspot/rev/a79cb7c55012

EVALUATION The suggestion in Description section will be implemented.