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  1. JDK
  2. JDK-8213199

GC abstraction for Assembler::needs_explicit_null_check()

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    Details

    • Type: Enhancement
    • Status: Resolved
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 12
    • Fix Version/s: 12
    • Component/s: hotspot
    • Subcomponent:
      gc
    • Resolved In Build:
      b20
    • CPU:
      generic
    • OS:
      generic

      Description

      GCs (like Shenandoah) may emit additional loads or stores. In the case of Shenandoah, we emit forward pointer loads from offset -8. Those accesses don't match the pattern currently checked in Assembler::needs_explicit_null_check() which means that explicit null checks would be emitted for forwarding pointer loads. But we don't want that because we know that the base object cannot be NULL (everything else would be an error).

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              Assignee:
              rkennke Roman Kennke
              Reporter:
              rkennke Roman Kennke
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                Dates

                Created:
                Updated:
                Resolved: