Hooking up the array mismatch stub as an intrinsic in the template interpreter

[Coleen Phillimore]

I don't know why we'd add even more assembly code to the interpreter.  
Why doesn't the JIT optimize this function instead? By adding a stub in 
the interpreter does that prevent the JIT from inlining this function 
since it's not invocation counted?

thanks,
Coleen


On 4/14/16 10:53 AM, Paul Sandoz wrote:
> Hi,
>
> I hooked up the array mismatch stub to the interpreter, with a bit of code cargo culting the CRC work and some lldb debugging [*] it appears to work and pass tests.
>
> Can someone have a quick look to see if i am not the right track here:
>
>    http://cr.openjdk.java.net/~psandoz/jdk9/JDK-8151268-int-c1-mismatch/webrev/ <http://cr.openjdk.java.net/~psandoz/jdk9/JDK-8151268-int-c1-mismatch/webrev/>
>
>
> Here are some quick numbers running using -Xint for byte[] equality:
>
> Benchmark              (lastNEQ)   (n)  Mode  Cnt       Score      Error  Units
> # Baseline
> # VM options: -Xint
> ByteArray.base_equals      false  1024  avgt   10  16622.453 ± 498.475  ns/op
> ByteArray.base_equals       true  1024  avgt   10  16889.244 ± 439.895  ns/op
>
> # Before patch
> # VM options: -Xint -XX:-UseVectorizedMismatchIntrinsic
> ByteArray.jdk_equals       false  1024  avgt   10  106436.195 ± 3657.508  ns/op
> ByteArray.jdk_equals        true  1024  avgt   10  103306.001 ± 2723.130  ns/op
>
> # After patch
> # VM options: -Xint -XX:+UseVectorizedMismatchIntrinsic
> ByteArray.jdk_equals       false  1024  avgt   10    448.764 ±  18.977  ns/op
> ByteArray.jdk_equals        true  1024  avgt   10    448.657 ±  22.656  ns/op
>
>
>
> The next step is to wire up C1.
>
> Further steps would be to substitute some of intrinsics added/used for compact strings with mismatch, then evaluate the performance.
>
> Thanks,
> Paul.
>
> [*] Stubs to be used as intrinsics in the template interpreter need to be created during the initial stage of generation, otherwise the stub address is null which leads to a SEGV that’s hard to track down.