RFR (XS): Set matrix update probability to low in conditional

[Roman Kennke]

Am 20.03.2017 um 14:26 schrieb Aleksey Shipilev:
> Hi,
>
> We can make the generated code a bit better by putting "unlikely" branch profile
> hint on the conditional matrix update:
>  http://cr.openjdk.java.net/~shade/shenandoah/matrix-c2-prob/webrev.01/
>
> Seems to help workloads that are sensitive to matrix barriers:
>
> Benchmark            Mode  Cnt    Score   Error    Units
>
> # Baseline, -UseMatrix
> Compiler.compiler   thrpt   50   93.041 ± 1.177  ops/min
> Compiler.sunflow    thrpt   50  225.488 ± 3.148  ops/min
> XmlValidation.test  thrpt   50  284.879 ± 1.190  ops/min
>
> # Baseline, +UseMatrix
> Compiler.compiler   thrpt   50   79.702 ± 0.805  ops/min
> Compiler.sunflow    thrpt   50  197.360 ± 2.629  ops/min
> XmlValidation.test  thrpt   50  254.786 ± 0.881  ops/min
>
> # Patched, +UseMatrix
> Compiler.compiler   thrpt   50   82.011 ± 0.865  ops/min
> Compiler.sunflow    thrpt   50  202.404 ± 3.808  ops/min
> XmlValidation.test  thrpt   50  257.733 ± 0.912  ops/min
>
> Testing: hotspot_gc_shenandoah
>
> Thanks,
> -Aleksey
>
Yes!

Roman