8346470: Improve WriteBarrier JMH to have old-to-young refs

[ericcaspole]

Adds new cases based on the existing ones using an extra iteration setup to allocate into young gen, allowing to test old-to-young stores etc, where the existing code is all old-to-old.

Here is a run on a standard OCI A1.160 with JDK 25:

Benchmark                                                                         Mode  Cnt     Score    Error  Units
WriteBarrier.WithDefaultUnrolling.testArrayWriteBarrierFastPathNullLarge          avgt   12  3448.826 ±  1.620  ns/op
WriteBarrier.WithDefaultUnrolling.testArrayWriteBarrierFastPathNullSmall          avgt   12    63.740 ±  0.151  ns/op
WriteBarrier.WithDefaultUnrolling.testArrayWriteBarrierFastPathNullYoungLarge     avgt   12  3448.353 ±  0.860  ns/op
WriteBarrier.WithDefaultUnrolling.testArrayWriteBarrierFastPathNullYoungSmall     avgt   12    63.565 ±  0.132  ns/op
WriteBarrier.WithDefaultUnrolling.testArrayWriteBarrierFastPathOldToYoungLarge    avgt   12  4476.390 ±  0.930  ns/op
WriteBarrier.WithDefaultUnrolling.testArrayWriteBarrierFastPathOldToYoungSmall    avgt   12    73.517 ±  0.082  ns/op
WriteBarrier.WithDefaultUnrolling.testArrayWriteBarrierFastPathRealLarge          avgt   12  3103.911 ±  2.079  ns/op
WriteBarrier.WithDefaultUnrolling.testArrayWriteBarrierFastPathRealSmall          avgt   12    57.549 ±  0.512  ns/op
WriteBarrier.WithDefaultUnrolling.testArrayWriteBarrierFastPathYoungToOldLarge    avgt   12  9587.762 ±  2.044  ns/op
WriteBarrier.WithDefaultUnrolling.testArrayWriteBarrierFastPathYoungToOldSmall    avgt   12   157.244 ±  0.169  ns/op
WriteBarrier.WithDefaultUnrolling.testArrayWriteBarrierFastPathYoungToYoungLarge  avgt   12  3103.191 ±  1.100  ns/op
WriteBarrier.WithDefaultUnrolling.testArrayWriteBarrierFastPathYoungToYoungSmall  avgt   12    57.392 ±  0.624  ns/op
WriteBarrier.WithDefaultUnrolling.testFieldWriteBarrierFastPath                   avgt   12     2.668 ±  0.001  ns/op
WriteBarrier.WithDefaultUnrolling.testFieldWriteBarrierFastPathYoungRef           avgt   12     9.337 ±  0.001  ns/op
WriteBarrier.WithoutUnrolling.testArrayWriteBarrierFastPathNullLarge              avgt   12  3449.234 ±  1.840  ns/op
WriteBarrier.WithoutUnrolling.testArrayWriteBarrierFastPathNullSmall              avgt   12    63.720 ±  0.079  ns/op
WriteBarrier.WithoutUnrolling.testArrayWriteBarrierFastPathNullYoungLarge         avgt   12  3448.055 ±  0.665  ns/op
WriteBarrier.WithoutUnrolling.testArrayWriteBarrierFastPathNullYoungSmall         avgt   12    63.555 ±  0.116  ns/op
WriteBarrier.WithoutUnrolling.testArrayWriteBarrierFastPathOldToYoungLarge        avgt   12  4476.646 ±  1.560  ns/op
WriteBarrier.WithoutUnrolling.testArrayWriteBarrierFastPathOldToYoungSmall        avgt   12    73.525 ±  0.070  ns/op
WriteBarrier.WithoutUnrolling.testArrayWriteBarrierFastPathRealLarge              avgt   12  3104.395 ±  1.537  ns/op
WriteBarrier.WithoutUnrolling.testArrayWriteBarrierFastPathRealSmall              avgt   12    57.766 ±  0.136  ns/op
WriteBarrier.WithoutUnrolling.testArrayWriteBarrierFastPathYoungToOldLarge        avgt   12  9586.585 ±  1.086  ns/op
WriteBarrier.WithoutUnrolling.testArrayWriteBarrierFastPathYoungToOldSmall        avgt   12   157.147 ±  0.128  ns/op
WriteBarrier.WithoutUnrolling.testArrayWriteBarrierFastPathYoungToYoungLarge      avgt   12  3103.531 ±  0.883  ns/op
WriteBarrier.WithoutUnrolling.testArrayWriteBarrierFastPathYoungToYoungSmall      avgt   12    57.669 ±  0.620  ns/op
WriteBarrier.WithoutUnrolling.testFieldWriteBarrierFastPath                       avgt   12     2.668 ±  0.001  ns/op
WriteBarrier.WithoutUnrolling.testFieldWriteBarrierFastPathYoungRef               avgt   12     9.337 ±  0.001  ns/op

---

Progress

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Issue

• JDK-8346470: Improve WriteBarrier JMH to have old-to-young refs (Enhancement - P4)

Reviewers

• Thomas Schatzl (@tschatzl - Reviewer)

Reviewing

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$ git pr checkout 24010

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[ericcaspole]

/label gc

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[openjdk]

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

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8346470: Improve WriteBarrier JMH to have old-to-young refs

Reviewed-by: tschatzl

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At the time when this comment was updated there had been 50 new commits pushed to the master branch:

• 4e51a8c: 8307513: C2: intrinsify Math.max(long,long) and Math.min(long,long)
• 7e3bc81: 8351216: ZGC: Store NUMA node count
• 82eb780: 8351349: GSSUtil.createSubject has outdated access control context and policy related text
• c3db667: 8351542: LIBMANAGEMENT_OPTIMIZATION remove special optimization settings
• 375722f: 8351839: RISC-V: Fix base offset calculation introduced in JDK-8347489
• 4c5956d: 8350866: [x86] Add C1 intrinsics for CRC32-C
• 9c00331: 8330469: C2: Remove or change "PrintOpto && VerifyLoopOptimizations" as printing code condition
• c18494d: 8351108: ImageIO.write(..) fails with exception when writing JPEG with IndexColorModel
• 86860ca: 8346916: [REDO] align_up has potential overflow
• a33b1f7: 8345298: RISC-V: Add riscv backend for Float16 operations - scalar
• ... and 40 more: https://git.openjdk.org/jdk/compare/73465b9866da8e97e557d6ad80a95568ada3ee01...master

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[openjdk]

@ericcaspole
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[ericcaspole]

/label hotspot-gc, hotspot-compiler

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@ericcaspole
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[mlbridge]

Webrevs

• 01: Full - Incremental (46da7dbc)
• 00: Full (7075365a)

[tschatzl]

Some minor formatting issues...

[ericcaspole]

Updated the code with Thomas' suggestions.

[ericcaspole]

/integrate

[openjdk]

Going to push as commit 03ef79c.
Since your change was applied there have been 54 commits pushed to the master branch:

• b50fe9b: 8280818: Expand bug8033699.java to iterate over all LaFs
• 771e160: 8351323: Parameterize compiler and linker flags for iconv
• 0ff1c08: 8349984: (jdeps) jdeps can use String.repeat instead of String.replaceAll
• 37ec796: 8351500: G1: NUMA migrations cause crashes in region allocation
• 4e51a8c: 8307513: C2: intrinsify Math.max(long,long) and Math.min(long,long)
• 7e3bc81: 8351216: ZGC: Store NUMA node count
• 82eb780: 8351349: GSSUtil.createSubject has outdated access control context and policy related text
• c3db667: 8351542: LIBMANAGEMENT_OPTIMIZATION remove special optimization settings
• 375722f: 8351839: RISC-V: Fix base offset calculation introduced in JDK-8347489
• 4c5956d: 8350866: [x86] Add C1 intrinsics for CRC32-C
• ... and 44 more: https://git.openjdk.org/jdk/compare/73465b9866da8e97e557d6ad80a95568ada3ee01...master

Your commit was automatically rebased without conflicts.

[openjdk]

@ericcaspole Pushed as commit 03ef79c.

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