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  1. JDK
  2. JDK-8176518

C2: Invalid ImplicitNullChecks with non-protected heap base

    Details

    • Type: Bug
    • Status: Closed
    • Priority: P2
    • Resolution: Fixed
    • Affects Version/s: 9, 10
    • Fix Version/s: 9
    • Component/s: hotspot
    • Labels:
    • Subcomponent:
    • Resolved In Build:
      b164
    • CPU:
      ppc
    • OS:
      aix
    • Verification:
      Not verified

      Backports

        Description

        We have observed that C2 generates implicit null checks for write accesses to the heap base even though it was not protected (narrow_oop_use_implicit_null_checks = false).
        The problem showed up on AIX with -XX:HeapBaseMinAddress=32g. ReservedHeapSpace::establish_noaccess_prefix protects the base area on almost all platforms, but not on AIX (in some case).
        PhaseCFG::implicit_null_check needs to skip the transformation in this case.

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                • Assignee:
                  mdoerr Martin Doerr
                  Reporter:
                  mdoerr Martin Doerr
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                  • Created:
                    Updated:
                    Resolved: