RFR(XS) : 8038240 : new WB API to get nmethod

[Vladimir Kozlov]

John,

Current WB osr tests are very simple with only one loop (in 
CompilerWhiteBoxTest.java):

      private int osrMethod() {
          int result = 0;
          for (long i = 0; i < CompilerWhiteBoxTest.BACKEDGE_THRESHOLD; 
++i) {
             result += method();
          }
          return result;
      }

So using Boolean should be fine for now. But it would need to be 
extended, as you suggested, if we add more complex loops.

Thanks,
Vladimir

On 3/25/14 2:01 PM, John Rose wrote:
> The boolean parameter is not expressive enough.  It will have to change as soon as we have more than two versions of a method.
>
> (In fact, we already do:  There is potentially a different OSR method for each entry point BCI.  The formulation you have returns just one of them.)
>
> I suggest you change "boolean isOsr" in the WB API to "long version" or even "Object version".  The version enumeration can be evolved over time.  Values 0 and 1 can be "normal at current compilation" and "first available OSR".
>
> Also, put the version number into the NMethod structure, so it can be requeried.  For an OSR method, the entry BCI is important to know.
>
> ...But I see that there is already a use of booleans like this in the WB API.  So I guess you should consistent with what you have.
>
> I filed a bug to track this issue of method versioning; there is technical debt here:
>    https://bugs.openjdk.java.net/browse/JDK-8038356
>
> — John
>