8252990: Intrinsify Unsafe.storeStoreFence

[shipilev]

Unsafe.storeStoreFence currently delegates to stronger Unsafe.storeFence. We can teach compilers to map this directly to already existing rules that handle MemBarStoreStore. Like explicit LoadFence/StoreFence, we introduce the special node to differentiate explicit fence and implicit store-store barriers. storeStoreFence is usually used to simulate safe final-field like constructions in special JDK classes, like ConstantCallSite and friends.

Motivational performance difference on benchmarks from JDK-8276054 on ARM32 (Raspberry Pi 4):

Benchmark                      Mode  Cnt   Score    Error  Units
Multiple.plain                 avgt    3   2.669 ±  0.004  ns/op
Multiple.release               avgt    3  16.688 ±  0.057  ns/op
Multiple.storeStore            avgt    3  14.021 ±  0.144  ns/op // Better

MultipleWithLoads.plain        avgt    3   4.672 ±  0.053  ns/op
MultipleWithLoads.release      avgt    3  16.689 ±  0.044  ns/op
MultipleWithLoads.storeStore   avgt    3  14.012 ±  0.010  ns/op // Better

MultipleWithStores.plain       avgt    3  14.687 ±  0.009  ns/op
MultipleWithStores.release     avgt    3  45.393 ±  0.192  ns/op
MultipleWithStores.storeStore  avgt    3  38.048 ±  0.033  ns/op // Better

Publishing.plain               avgt    3  27.079 ±  0.201  ns/op
Publishing.release             avgt    3  27.088 ±  0.241  ns/op
Publishing.storeStore          avgt    3  27.009 ±  0.259  ns/op // Within error, hidden by allocation

Single.plain                   avgt    3   2.670 ± 0.002  ns/op
Single.releaseFence            avgt    3   6.675 ± 0.001  ns/op
Single.storeStoreFence         avgt    3   8.012 ± 0.027  ns/op  // Worse, seems to be ARM32 implementation artifact

The same thing on AArch64 (Raspberry Pi 3):

Benchmark                      Mode  Cnt   Score   Error  Units

Multiple.plain                 avgt    3   5.914 ± 0.115  ns/op
Multiple.release               avgt    3  10.149 ± 0.059  ns/op
Multiple.storeStore            avgt    3   6.757 ± 0.138  ns/op // Better

MultipleWithLoads.plain        avgt    3  11.849 ± 0.331  ns/op
MultipleWithLoads.release      avgt    3  35.565 ± 1.144  ns/op
MultipleWithLoads.storeStore   avgt    3  19.441 ± 0.471  ns/op // Better

MultipleWithStores.plain       avgt    3   5.920 ± 0.213  ns/op
MultipleWithStores.release     avgt    3  20.286 ± 0.347  ns/op
MultipleWithStores.storeStore  avgt    3  12.686 ± 0.230  ns/op // Better

Publishing.plain               avgt    3  22.261 ± 1.630  ns/op
Publishing.release             avgt    3  22.269 ± 0.576  ns/op
Publishing.storeStore          avgt    3  17.464 ± 0.397  ns/op // Better

Single.plain                   avgt    3   5.916 ± 0.063  ns/op
Single.release                 avgt    3  10.148 ± 0.401  ns/op
Single.storeStore              avgt    3   6.767 ± 0.164  ns/op // Better

As expected, this does not affect x86_64 at all, because both release and storeStore are effectively no-ops, only affecting compiler optimizations:

Benchmark                      Mode  Cnt  Score   Error  Units

Multiple.plain                 avgt    3  0.406 ± 0.002  ns/op
Multiple.release               avgt    3  0.409 ± 0.018  ns/op
Multiple.storeStore            avgt    3  0.406 ± 0.001  ns/op

MultipleWithLoads.plain        avgt    3  4.328 ± 0.006  ns/op
MultipleWithLoads.release      avgt    3  4.600 ± 0.014  ns/op
MultipleWithLoads.storeStore   avgt    3  4.602 ± 0.006  ns/op

MultipleWithStores.plain       avgt    3  0.812 ± 0.001  ns/op
MultipleWithStores.release     avgt    3  0.812 ± 0.002  ns/op
MultipleWithStores.storeStore  avgt    3  0.812 ± 0.002  ns/op

Publishing.plain               avgt    3  6.370 ± 0.059  ns/op
Publishing.release             avgt    3  6.358 ± 0.436  ns/op
Publishing.storeStore          avgt    3  6.367 ± 0.054  ns/op

Single.plain                   avgt    3  0.407 ± 0.039  ns/op
Single.releaseFence            avgt    3  0.406 ± 0.001  ns/op
Single.storeStoreFence         avgt    3  0.406 ± 0.001  ns/op

Additional testing:

• Linux x86_64 fastdebug tier1
• Linux AArch64 fastdebug tier1
• Linux x86_64 Fences benchmark
• Linux AArch64 Fences benchmark
• Linux ARM32 Fences benchmark
• Linux AArch64 jcstress quick run

---

Progress

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• Commit message must refer to an issue
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Issue

• JDK-8252990: Intrinsify Unsafe.storeStoreFence

Reviewers

• David Holmes (@dholmes-ora - Reviewer) ⚠️ Review applies to 5277aa2
• Tobias Hartmann (@TobiHartmann - Reviewer)
• Wang Huang (@Wanghuang-Huawei - Author)

Reviewing

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[mlbridge]

Webrevs

• 01: Full - Incremental (1f24d71c)
• 00: Full (5277aa2a)

[dholmes-ora]

I'm certainly no JIT expert but the pattern for adding the new intrinsic seems consistent with the existing code.

Thanks,
David

[openjdk]

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

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8252990: Intrinsify Unsafe.storeStoreFence

Reviewed-by: dholmes, thartmann, whuang

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At the time when this comment was updated there had been 99 new commits pushed to the master branch:

• 92be9d8: 8276236: Table headers missing in Formatter api docs
• 9bf3165: 8276164: RandomAccessFile#write method could throw IndexOutOfBoundsException that is not described in javadoc
• 0488ebd: 8276105: C2: Conv(D|F)2(I|L)Nodes::Ideal should handle rounding correctly
• acceffc: 8273704: DrawStringWithInfiniteXform.java failed : drawString with InfiniteXform transform takes long time
• 2eafa03: 8276234: Trivially clean up locale-related code
• 47e7a42: 8262945: [macos] Regression Manual Test for Key Events Fails
• 99b7b95: 8276205: Shenandoah: CodeCache_lock should always be held for initializing code cache iteration
• 9771544: 8260428: Drop support for pre JDK 1.4 DatagramSocketImpl implementations
• e265f83: 8276107: Preventive collections trigger before maxing out heap
• c8abe35: 8276121: G1: Remove unused and uninitialized _g1h in g1SATBMarkQueueSet.hpp
• ... and 89 more: https://git.openjdk.java.net/jdk/compare/f6232982b91cb2314e96ddbde3984836a810a556...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

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[TobiHartmann]

That looks good to me.

[Wanghuang-Huawei]

LGTM

[shipilev]

Finally revived my quiet AArch64 dev board, added AArch64 results, which are even better than ARM32. Updated PR with perf results.

[shipilev]

jcstress and tier1 passes on AArch64. Seems like we are good to go.

/integrate

[openjdk]

Going to push as commit b7a06be.
Since your change was applied there have been 99 commits pushed to the master branch:

• 92be9d8: 8276236: Table headers missing in Formatter api docs
• 9bf3165: 8276164: RandomAccessFile#write method could throw IndexOutOfBoundsException that is not described in javadoc
• 0488ebd: 8276105: C2: Conv(D|F)2(I|L)Nodes::Ideal should handle rounding correctly
• acceffc: 8273704: DrawStringWithInfiniteXform.java failed : drawString with InfiniteXform transform takes long time
• 2eafa03: 8276234: Trivially clean up locale-related code
• 47e7a42: 8262945: [macos] Regression Manual Test for Key Events Fails
• 99b7b95: 8276205: Shenandoah: CodeCache_lock should always be held for initializing code cache iteration
• 9771544: 8260428: Drop support for pre JDK 1.4 DatagramSocketImpl implementations
• e265f83: 8276107: Preventive collections trigger before maxing out heap
• c8abe35: 8276121: G1: Remove unused and uninitialized _g1h in g1SATBMarkQueueSet.hpp
• ... and 89 more: https://git.openjdk.java.net/jdk/compare/f6232982b91cb2314e96ddbde3984836a810a556...master

Your commit was automatically rebased without conflicts.

[openjdk]

@shipilev Pushed as commit b7a06be.

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