RFR(S): 6378256: Performance problem with System.identityHashCode in client compiler

[Roland Westrelin]

Hi Rahul,

> Please review revised patch, notes for JDK-6378256.
> https://bugs.openjdk.java.net/browse/JDK-6378256
> 
> 
> Latest webrev-03: http://cr.openjdk.java.net/~thartmann/6378256/webrev.03/

Thanks for making the change. I would say it’s better to add inline_check_hashcode_from_object_header() to sharedRuntime.hpp with #ifdef X86 rather than have the inline declaration. Not sure what others think.

>>> Can you justify the comments again?

I meant justify as text justification that is right align that comment:

  36 // ---------------------------------------------------------------------------
  37 // Object.hashCode, System.identityHashCode can pull the hashCode from the header word
  38 // instead of doing a full VM transition once it's been computed.
  39 // Since hashCode is usually polymorphic at call sites we can't do
  40 // this optimization at the call site without a lot of work.

and that comment

2019     // Object.hashCode, System.identityHashCode can pull the hashCode from the header word
2020     // instead of doing a full VM transition once it's been computed.
2021     // Since hashCode is usually polymorphic at call sites we can't do
2022     // this optimization at the call site without a lot of work.

Sorry for the confusion. The code looks good to me/

Roland.