Integrated: 8284579: Improve VarHandle checks for interpreter

[Claes Redestad]

On Fri, 8 Apr 2022 11:48:10 GMT, Claes Redestad <redestad at openjdk.org> wrote:

> A few additional enhancements aiming to improve VH performance in the interpreter:
> 
> - Flatten `TypeAndInvokers`: adds a pointer to `VarHandle` (a small increase 40->48) but removes an object and an indirection on any instance actually used - and might avoid allocating the `MethodHandle[]` unnecessarily on some instances
> - Have `checkExactAccessMode` return the directness of the `VarHandle` so that we can avoid some `isDirect` method calls.
> 
> Baseline, `-Xint`
> 
> Benchmark                                 Mode  Cnt    Score   Error  Units
> VarHandleExact.exact_exactInvocation      avgt   30  478.324 ? 5.762  ns/op
> VarHandleExact.generic_exactInvocation    avgt   30  392.114 ? 1.644  ns/op
> VarHandleExact.generic_genericInvocation  avgt   30  822.484 ? 1.865  ns/op
> 
> 
> Patched, `-Xint`
> 
> Benchmark                                 Mode  Cnt    Score   Error  Units
> VarHandleExact.exact_exactInvocation      avgt   30  437.704 ? 5.320  ns/op
> VarHandleExact.generic_exactInvocation    avgt   30  374.512 ? 3.154  ns/op
> VarHandleExact.generic_genericInvocation  avgt   30  757.054 ? 1.237  ns/op
> 
> 
> No significant performance difference in normal mode.

This pull request has now been integrated.

Changeset: 280aa428
Author:    Claes Redestad <redestad at openjdk.org>
URL:       https://git.openjdk.java.net/jdk/commit/280aa428800043f314b92ae88076d596cb4c2fe0
Stats:     244 lines in 4 files changed: 26 ins; 28 del; 190 mod

8284579: Improve VarHandle checks for interpreter

Reviewed-by: mcimadamore, mchung

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PR: https://git.openjdk.java.net/jdk/pull/8160