JDK-8028471 : PPC64 (part 215): opto: Extend ImplicitNullCheck optimization.
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: port-stage-ppc-aix
  • Priority: P4
  • Status: Resolved
  • Resolution: Fixed
  • OS: aix
  • CPU: ppc
  • Submitted: 2013-11-16
  • Updated: 2017-02-23
  • Resolved: 2013-11-22
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JDK 8 JDK 9 Other
8u20Fixed 9Fixed openjdk7u,port-stage-ppc-aixFixed
ImplicitNullChecks did not work on platforms where the zero
page is only write protected.
This change adds os property 'zero_page_read_protected' and extends
the ImplicitNullCheck optimization to consider only stores if
this property is not true.  If a decoded compressed oop will access the 
guard page before the heap, Loads work again.
This is needed on AIX, where the page at address '0' is only write-protected.


This is preparation for PPC64 integration: http://openjdk.java.net/jeps/175
This and following ppc64 changes will go into staging repository first and tested there: http://hg.openjdk.java.net/ppc-aix-port/stage/