8326235: RISC-V: Size CodeCache for short calls encoding

[robehn]

Hi, please consider.

This limits the code cache to a size such that all code cache -> code cache calls and jump may always use auipc+jalr.
(this is what we do in practice)
Thus we can fix the encoding for those and not have variable encoding.
The reduction of the size is just 2k, but due to option passing the real reduction is probably 1M.
-XX:ReservedCodeCacheSize=2047M (down from 2048)

Note, specifying '2G' gives the message:

Invalid ReservedCodeCacheSize=2048M. Must be at most 2047M.

Manually test, no test I found uses this large code cache.

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Issue

• JDK-8326235: RISC-V: Size CodeCache for short calls encoding (Enhancement - P4)

Reviewers

• Fei Yang (@RealFYang - Reviewer)
• Antonios Printezis (@gctony - Reviewer)

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• 00: Full (095e338d)

[RealFYang]

Thanks for fixing this potential risk. We will be more certain in code emitted for a cc -> cc call. In fact, I was also planning to do a similar fix for this very uncommon case :-)

[openjdk]

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

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

8326235: RISC-V: Size CodeCache for short calls encoding

Reviewed-by: fyang, tonyp

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At the time when this comment was updated there had been 27 new commits pushed to the master branch:

• 33834b7: 8326375: [REDO] Clean up NativeCompilation.gmk and its newly created parts
• 2352268: 8326334: JFR failed assert(used(klass)) failed: invariant
• 492e8bf: 8325587: Shenandoah: ShenandoahLock should allow blocking in VM
• 5f16f34: 8326370: Remove redundant and misplaced micros from StringBuffers
• 921507c: 8326319: G1: Remove unused G1ConcurrentMark::_init_times
• 68eb5a1: 8321075: RISC-V: UseSystemMemoryBarrier lacking proper OS support
• 04d43c4: 8187759: Background not refreshed when painting over a transparent JFrame
• d5f3d5c: 8326201: [S390] Need to bailout cleanly if creation of stubs fails when code cache is out of space
• d31fd78: 8325496: Make TrimNativeHeapInterval a product switch
• 27003b5: 8326090: Rename jvmti_aod.h
• ... and 17 more: https://git.openjdk.org/jdk/compare/69a11c7f7ea7c4195a8ee56391bdf04c75bd8156...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.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[robehn]

Thanks for fixing this potential risk. We will be more certain in code emitted for a cc -> cc call. In fact, I was also planning to do a similar fix for this very uncommon case :-)

Thanks!

[gctony]

Looks good.

[robehn]

Looks good.

Thanks!

[robehn]

/integrate

[openjdk]

Going to push as commit 51e2dde.
Since your change was applied there have been 28 commits pushed to the master branch:

• c022431: 8326412: debuginfo files should not have executable bit set
• 33834b7: 8326375: [REDO] Clean up NativeCompilation.gmk and its newly created parts
• 2352268: 8326334: JFR failed assert(used(klass)) failed: invariant
• 492e8bf: 8325587: Shenandoah: ShenandoahLock should allow blocking in VM
• 5f16f34: 8326370: Remove redundant and misplaced micros from StringBuffers
• 921507c: 8326319: G1: Remove unused G1ConcurrentMark::_init_times
• 68eb5a1: 8321075: RISC-V: UseSystemMemoryBarrier lacking proper OS support
• 04d43c4: 8187759: Background not refreshed when painting over a transparent JFrame
• d5f3d5c: 8326201: [S390] Need to bailout cleanly if creation of stubs fails when code cache is out of space
• d31fd78: 8325496: Make TrimNativeHeapInterval a product switch
• ... and 18 more: https://git.openjdk.org/jdk/compare/69a11c7f7ea7c4195a8ee56391bdf04c75bd8156...master

Your commit was automatically rebased without conflicts.

[openjdk]

@robehn Pushed as commit 51e2dde.

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