RFR: 8340183: Shenandoah: Incorrect match for clone barrier in is_gc_barrier_node

[Roman Kennke]

On Mon, 16 Sep 2024 10:35:15 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> The name of the call we emit is "shenandoah_clone":
> https://github.com/openjdk/jdk/blob/545951889c1ea68646be600decaf2bf4c049600b/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp#L806
> 
> ...yet we test for "shenandoah_clone_barrier" here:
> https://github.com/openjdk/jdk/blob/545951889c1ea68646be600decaf2bf4c049600b/src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp#L688
> 
> I think we are better off polling the call target instead of relying on call name. This change also eliminates `shenandoah_cas_obj` matcher, for which we do not have the emitted call ever since we started doing CAS expansions inline.
> 
> Additional testing:
>  - [x] Linux x86_64 server fastdebug, `hotspot_gc_shenandoah`
>  - [ ] Linux x86_64 server fastdebug, `all` with `-XX:+UseShenandoahGC`

Looks good, thank you!

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Marked as reviewed by rkennke (Reviewer).

PR Review: https://git.openjdk.org/jdk/pull/21014#pullrequestreview-2322461615