Integrated: 8346194: Improve G1 pre-barrier C2 cost estimate

[Thomas Schatzl]

On Mon, 3 Mar 2025 12:30:23 GMT, Thomas Schatzl <tschatzl at openjdk.org> wrote:

> Hi all,
> 
>   please review this change that modifies pre-barrier node costs for loop-unrolling to only consider the fast path. The reasoning is similar to zgc (and the new costs as well): only the part of the barrier inlined into the main code stream, as the slow path is laid out separately and does/should not directly affect performance (particularly if there is no marking going on).
> 
> There are no differences/impact in performance since the post barrier cost is still very large, which fill be fixed elsewhere.
> 
> Testing: gha, perf testing standalone (neither micros nor actual benchmarks give any difference outside of variance), testing with JDK-8342382
> 
> Hth,
>   Thomas

This pull request has now been integrated.

Changeset: 9f8d833f
Author:    Thomas Schatzl <tschatzl at openjdk.org>
URL:       https://git.openjdk.org/jdk/commit/9f8d833f8654cb4280d002ef86ce3ae9d709eddc
Stats:     11 lines in 1 file changed: 5 ins; 5 del; 1 mod

8346194: Improve G1 pre-barrier C2 cost estimate

Co-authored-by: Roberto Castañeda Lozano <rcastanedalo at openjdk.org>
Reviewed-by: rcastanedalo, ayang

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PR: https://git.openjdk.org/jdk/pull/23862