8384080: Shenandoah: Simplify C1 CAS barriers

[shipilev]

In Shenandoah LBE, we have switched to a more succinct way to deal with concurrent evacuation false negatives in atomics: do the fix up early on, thus avoiding any need for CAS retry logic.

This one handles the C1 side. Since we no longer have Shenandoah-specific LIR nodes, and we do not call into platform-specific ShenandoahBarrierSetAssembler from their respective emits, this allows us to do everything in shared code, greatly reducing platform-specific implementations. The barrier bindings follow the shape we did in native barrier set, JDK-8383810.

Additional testing:

• Linux x86_64 server fastdebug, hotspot_gc_shenandoah
• Linux x86_64 server fastdebug, all with -XX:+UseShenandoahGC -XX:TieredStopAtLevel=1
• Linux AArch64 server fastdebug, all with -XX:+UseShenandoahGC -XX:TieredStopAtLevel=1
• Linux x86_64 server release, jcstress with -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=aggressive
• Linux AArch64 server release, jcstress with -XX:+UseShenandoahGC -XX:ShenandoahGCHeuristics=aggressive

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Issue

• JDK-8384080: Shenandoah: Simplify C1 CAS barriers (Enhancement - P4)

Reviewers

• Kelvin Nilsen (@kdnilsen - Reviewer)
• Roman Kennke (@rkennke - Reviewer)

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@shipilev This change now passes all automated pre-integration checks.

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8384080: Shenandoah: Simplify C1 CAS barriers

Reviewed-by: kdnilsen, rkennke

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At the time when this comment was updated there had been 26 new commits pushed to the master branch:

• 84afc28: 8384089: Correctly catch invalid uses of StubCodeMark
• 18d0d27: 8382035: [ubsan] Under UBSAN builds, disable tests that rely on simulated JVM crashes
• 88ac00a: 8384097: G1: G1ConcurrentMarkThread::total_mark_cpu_time_s adds together nanoseconds and seconds
• ... and 23 more: https://git.openjdk.org/jdk/compare/b337599da27b7659d816f3c4e91566543bbbcc25...master

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[shipilev]

Looks like it passes the tests. @rkennke, @earthling-amzn, @kdnilsen -- please take a look. I would like to integrate it early next week, if nothing blocking appears. This would allow us to eliminate SBSA::cmpxchg_oop along with C2 CAS barrier rewrite in LBE, as LBE would eliminate the last use of it.

[kdnilsen]

Thanks.

[rkennke]

This is a nice simplification! The changes look good!