8257232: CompileThresholdScaling fails to work on 32-bit platforms

[DamonFool]

Hi all,

CompileThresholdScaling is incorrect on 32-bit platforms.

If you run the following command on Linux-32:

java -XX:CompileThresholdScaling=0.75 -version

It gets the following unexpected warnings:

intx Tier0InvokeNotifyFreqLog=32 is outside the allowed range [ 0 ... 30 ]
intx Tier0BackedgeNotifyFreqLog=32 is outside the allowed range [ 0 ... 30 ]
intx Tier2InvokeNotifyFreqLog=32 is outside the allowed range [ 0 ... 30 ]
intx Tier2BackedgeNotifyFreqLog=32 is outside the allowed range [ 0 ... 30 ]
intx Tier3InvokeNotifyFreqLog=32 is outside the allowed range [ 0 ... 30 ]
intx Tier3BackedgeNotifyFreqLog=32 is outside the allowed range [ 0 ... 30 ]
intx Tier23InlineeNotifyFreqLog=32 is outside the allowed range [ 0 ... 30 ]

The failure is that nth_bit(max_freq_bits) [1] = nth_bit(32) [2] = 0 on 32-bit platforms.
So the scaling logic is wrong.
It would be better to fix it.

Thanks.
Best regards,
Jie

[1] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/compiler/compilerDefinitions.cpp#L125
[2] https://github.com/openjdk/jdk/blob/master/src/hotspot/share/utilities/globalDefinitions.hpp#L973

---

Progress

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Issue

• JDK-8257232: CompileThresholdScaling fails to work on 32-bit platforms

Reviewers

• Vladimir Kozlov (@vnkozlov - Reviewer)
• Claes Redestad (@cl4es - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/1499/head:pull/1499
$ git checkout pull/1499

[DamonFool]

/issue add JDK-8257232
/test
/label add hotspot-compiler
/cc hotspot-compiler

[bridgekeeper]

👋 Welcome back jiefu! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

@DamonFool This issue is referenced in the PR title - it will now be updated.

[openjdk]

@DamonFool
The hotspot-compiler label was successfully added.

[openjdk]

@DamonFool The hotspot-compiler label was already applied.

[openjdk]

@DamonFool The hotspot-compiler label was already applied.

[mlbridge]

Webrevs

• 00: Full (2116b88)

[vnkozlov]

Good.

[openjdk]

@DamonFool 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:

8257232: CompileThresholdScaling fails to work on 32-bit platforms

Reviewed-by: kvn, redestad

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 56 new commits pushed to the master branch:

• cfd070e: 8257537: [vector] Cleanup redundant bitwise cases on floating point vectors
• 03f3b8e: 8210253: Clipped UI rendering with X11 pipeline and HiDPI
• ce496cb: 8257190: simplify PhaseIdealLoop constructors
• 927504e: 8256474: Migrate Mutex _owner accesses to use Atomic operations
• 00e79db: 8257511: JDK-8254082 brings regression to AbstractStringBuilder.insert(int dstOffset, CharSequence s, int start, int end)
• 015e6e5: 8257460: Further CompilerOracle cleanup
• 29d90b9: 8255968: Confusing error message for inaccessible constructor
• c5046ca: 8246739: InputStream.skipNBytes could be implemented more efficiently
• 56b15fb: 8159746: (proxy) Support for default methods
• 1433baf: 8253751: Dependencies of automatic modules are not propagated through module layers
• ... and 46 more: https://git.openjdk.java.net/jdk/compare/c93f0a07c4088ec6c393324e49f32e330f4a58a5...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.

[DamonFool]

Good.

Thanks @vnkozlov for your review.

May I get a second review for this change?
Thanks.

[cl4es]

Looks good to me.

Just an idea for a future RFE (one which I might pick up and work on myself): If the multiply-loop-based log2_intptr is a performance issue here, it could probably be optimized by building a variant based on count_leading_zeros. That would require lifting it out from globalDefinitions.hpp, so powerOfTwo.hpp might be a good place.

[cl4es]

Could be simplified to return MIN2(log2_intptr(scaled_freq), max_freq_bits);

[DamonFool]

Could be simplified to return MIN2(log2_intptr(scaled_freq), max_freq_bits);

OK.
Will use this kind of code style next time.
Thanks.

[DamonFool]

/integrate

[openjdk]

@DamonFool Since your change was applied there have been 56 commits pushed to the master branch:

• cfd070e: 8257537: [vector] Cleanup redundant bitwise cases on floating point vectors
• 03f3b8e: 8210253: Clipped UI rendering with X11 pipeline and HiDPI
• ce496cb: 8257190: simplify PhaseIdealLoop constructors
• 927504e: 8256474: Migrate Mutex _owner accesses to use Atomic operations
• 00e79db: 8257511: JDK-8254082 brings regression to AbstractStringBuilder.insert(int dstOffset, CharSequence s, int start, int end)
• 015e6e5: 8257460: Further CompilerOracle cleanup
• 29d90b9: 8255968: Confusing error message for inaccessible constructor
• c5046ca: 8246739: InputStream.skipNBytes could be implemented more efficiently
• 56b15fb: 8159746: (proxy) Support for default methods
• 1433baf: 8253751: Dependencies of automatic modules are not propagated through module layers
• ... and 46 more: https://git.openjdk.java.net/jdk/compare/c93f0a07c4088ec6c393324e49f32e330f4a58a5...master

Your commit was automatically rebased without conflicts.

Pushed as commit 8f4fa3f.

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