JDK-6339956 : Eliminate locking of unescaped objects
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 6
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • OS: generic
  • CPU: generic
  • Submitted: 2005-10-21
  • Updated: 2010-04-02
  • Resolved: 2005-12-07
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6 b63Fixed
Related Reports
Relates :  
Escape analysis was recently added to Compiler2.  However there are currently no
optimizations which take advantage of it.  Adding an optimization to eliminate
locking and unlocking of unescaped objects is an easy, safe optimization to
take advantage of escape analysis.

SUGGESTED FIX PRT webrev: http://analemma.sfbay.sun.com/net/prt-archiver.sfbay/data/archived_workspaces/main/c2_baseline/2005/20051130105101.steved.escape_analysis_ws/workspace/webrevs/webrev-2005.11.30/index.html

EVALUATION Eliminating locking on unescaped objects has been added. As part of this change, the bytecode escape estimator was added. Without it, almost no opportunities for this optimization are detected. This optimization is only effective when the DoEscapeAnalysis flag is turned on (it is off by default.)