JDK-6716785 : implicit null checks not triggering with CompressedOops
  • Type: Bug
  • Component: hotspot
  • Sub-Component: runtime
  • Affected Version: hs13,6u6p
  • Priority: P2
  • Status: Closed
  • Resolution: Fixed
  • OS: linux,linux_suse_sles_10
  • CPU: x86
  • Submitted: 2008-06-19
  • Updated: 2011-03-08
  • Resolved: 2011-03-08
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Unresolved : Release in which this issue/RFE will be addressed.
Resolved: Release in which this issue/RFE has been resolved.
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JDK 6 JDK 7 Other
6u14Fixed 7Fixed hs13Fixed
Related Reports
Duplicate :  
JDK-6719144 - "unhandled implicit exception in compiled code" assertion on linux-amd64 with CompressedOops in 6u6p
Duplicate :  
JDK-6719131 - jdwp tests fail with java.lang.ClassCastException, on linux-amd64 in -Xcomp mode with CompressedOops
Relates :  
JDK-2184534 - VM does not reserve protected page below heap for compressed oops implicit null checks
Relates :  
JDK-6896084 - VM does not reserve protected page below heap for compressed oops implicit null checks
Description
See comments.
Comments
EVALUATION This fix has been checked in for both hs13 (snapshot for b03) and in hs14.
22-07-2008
EVALUATION Add code to allocate extra space for java heap (either 1 page or alignment) and unprotect so that implicit null exceptions at heap_base + 1 page fault.
30-06-2008
SUGGESTED FIX The ultimate fix should be in runtime, in the short term we may want to have some variant of -UseImplicitNullChecks for narrow oops in C2.
25-06-2008
EVALUATION Implict null checks under CompressedOops are not triggering a change on control flow. It appears that the heap_base+1 page is still writeable, so the generated code does not SEGV as expected.
25-06-2008
EVALUATION -
19-06-2008