JDK-6746907 : Improve implicit null check generatation
  • Type: Enhancement
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: hs14
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • OS: solaris_10
  • CPU: sparc
  • Submitted: 2008-09-10
  • Updated: 2010-04-03
  • Resolved: 2008-09-23
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JDK 6 JDK 7 Other
6u14Fixed 7Fixed hs14Fixed
Description
VM doesn't generate implicit null check if there are empty blocks
between null test and uncommon_trap call.
Also VM specifies the holder of a tested oop in uncommon_trap's debug info
instead of passing NULL. This increase registers pressure.

Comments
SUGGESTED FIX Skip over empty blocks when looking for uncommon_trap and add the missing offset check for compressed oops when looking for an implicit null check opportunities. Use NULL as value for a tested oop in uncommon_trap's debug info.
11-09-2008

EVALUATION http://hg.openjdk.java.net/jdk7/hotspot-comp/hotspot/rev/c792b641b8bd
11-09-2008