[9] RFR (M): 8027827: Improve performance of catchException combinator

Marcus Lagergren marcus.lagergren at oracle.com
Thu Feb 20 15:31:30 UTC 2014

This looks good, and we have done a significant number of test runs to verify its integrity.

I say ship it. +1

We know that there are some issues with sun.misc.ValueConversion.castReference and similar internal methods not being inlined, but as far as I can understand this is a separate issue that will be addressed. By rewriting a guard for Nashorn to not use castReference in the fast case, I get record indy performance with your catch combinator.

/M (jdk9 reviewer)

On 19 Feb 2014, at 22:46, Vladimir Ivanov <vladimir.x.ivanov at oracle.com> wrote:

> http://cr.openjdk.java.net/~vlivanov/8027827/final/webrev.00
> https://jbs.oracle.com/bugs/browse/JDK-8027827
> 354 lines changed: 193 ins; 91 del; 70 mod
> MethodHandles.catchException combinator implementation is based on generic invokers (MethodHandleImpl$GuardWithCatch.invoke_*). It is significantly slower than a Java equivalent (try-catch).
> Future Nashorn performance improvements require catchException combinator speed to be on par with try-catch in Java.
> So, it should be represented in a more efficient form.
> I chose the following lambda form representation:
>  t_{i}:L=ValueConversions.array(a1:L,...,a_{k}:L);
> t_{i+1}:L=MethodHandleImpl.guardWithCatch(t_{p1}, t_{p2}, t_{p3}, t_{i}:L);
> t_{i+2}:I=ValueConversions.unbox(t7:L);
>     OR :L=ValueConversions.identity(t_{n+1})
>     OR :V=ValueConversions.ignore(t_{n+1})
> where:
>  a1, ..., a_{k} - arguments
>  t_{p1}, t_{p2}, t_{p3} - target method handle, exception class, catcher method handle respectively; passed as bounded parameters;
> During lambda form compilation it is converted into bytecode equivalent of the following Java code:
>  try {
>      return target.invokeBasic(...);
>  } catch(Throwable e) {
>      if (!exClass.isInstance(e)) throw e;
>      return catcher.invokeBasic(e, ...);
>  }
> There's a set of microbenchmarks (attached to the bug) I wrote to verify performance characteristics of new implementation.
> What is missing is lambda form caching. The plan is to have a single lambda form per basic type, but it needs more work - current representation is suitable for sharing on bytecode level, but lambda form interpretation doesn't work well (arguments boxing + result unboxing are problematic).
> Tests: microbenchmarks, jdk/java/lang/invoke/, nashorn with optimistic types (unit tests, octane).
> Tested in 2 modes:
>  * COMPILE_THRESHOLD=0 -Xverify:all
> 1) Update of cached name and member in LF compilation loop (see InvokerBytecodeGenerator.generateCustomizedCodeBytes) fixes a bug during compilation of selectAlternative when running with COMPILE_THRESHOLD=0.
> 2) As part of this change, I fix existing bug [1], so I add regression test for it.
> Thanks!
> Best regards,
> Vladimir Ivanov
> [1] https://bugs.openjdk.java.net/browse/JDK-8034120

More information about the core-libs-dev mailing list