8255762: Shenandoah: Consolidate/streamline interpreter LRBs

[rkennke]

We currently have two LRB implementations in interpreter: one normal and one for native/weak LRB. We should consolidate them into one.

The main issue here is that the two implementations follow different approaches:

• the normal LRB calls through the shenandoah_lrb stub which does additional null- and cset-checking
• the weak LRB calls to runtime directly and must not do cset-checking

The reason for calling through the stub is that it gives more freedom to allocate two registers that are required for the cset check. However, we can invert the cset addressing like we did in JDK-8245465 and save a register. We can also eliminate the null-check and let the cset-check subsume it (like we do everywhere else). Allocating a single register for the cset-check is easy, and we can do so in-line without the extra jump through the stub. The runtime call through the stub has also been very costly: it dumps 2KB of register data on the stack at each call, that is very excessive. save_xmm_registers() should be more than enough (in-fact, I am almost certain that this is excessive too, and we should only need to save/restore xmm0 - but not in this patch). Not needing to generate the call-stub is also helpful for backportability, because in jdk8-shenandoah we cannot do that.

Testing: hotspot_gc_shenandoah (x86_64, x86_32, aarch64)

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Progress

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Testing

	Linux x64	Linux x86	Windows x64	macOS x64
Build	⏳ (5/5 running)	⏳ (2/2 running)	⏳ (2/2 running)	⏳ (2/2 running)

Issue

• JDK-8255762: Shenandoah: Consolidate/streamline interpreter LRBs

Reviewers

• Aleksey Shipilev (@shipilev - Reviewer) ⚠️ Review applies to 12382e6

Download

$ git fetch https://git.openjdk.java.net/jdk pull/1010/head:pull/1010
$ git checkout pull/1010

[bridgekeeper]

👋 Welcome back rkennke! 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]

@rkennke The following labels will be automatically applied to this pull request:

• hotspot
• shenandoah

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing lists. If you would like to change these labels, use the /label pull request command.

[mlbridge]

Webrevs

• 02: Full - Incremental (f031885)
• 01: Full - Incremental (12382e6)
• 00: Full (6573511)

[shipilev]

This looks nice. Please run hotspot_gc_shenandoah on aarch64?

[shipilev]

Looks good, apart from two nits.

[openjdk]

@rkennke 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:

8255762: Shenandoah: Consolidate/streamline interpreter LRBs

Reviewed-by: shade

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 33 new commits pushed to the master branch:

• 63461d5: 8255072: [TESTBUG] com/sun/jdi/EATests.java should not fail if expected VMOutOfMemoryException is not thrown
• b8d4e02: 8255374: Add a dropReturn MethodHandle combinator
• 1d0bd50: 8254758: Change G1ServiceThread to be task based
• 9a0cf58: 8255615: Zero: demote ZeroStack::abi_stack_available guarantee to assert
• 904561e: 8255719: Zero: on return path, check for pending exception before attempting to clear it
• 9bd836e: 8255744: Zero: handle JVM_CONSTANT_DynamicInError
• 36998b0: 8255716: AArch64: Regression: JVM crashes if manually offline a core
• 4107670: 8233562: [TESTBUG] Swing StyledEditorKit test bug4506788.java fails on MacOS
• 9a36747: 8255780: Remove unused overloads of VMError::report_and_die()
• c96a914: 8255662: ZGC: Unify nmethod closures in the heap iterator
• ... and 23 more: https://git.openjdk.java.net/jdk/compare/1769c48342b68712cb25b7df747201f46b8b9d54...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.

[rkennke]

/integrate

[openjdk]

@rkennke Since your change was applied there have been 33 commits pushed to the master branch:

• 63461d5: 8255072: [TESTBUG] com/sun/jdi/EATests.java should not fail if expected VMOutOfMemoryException is not thrown
• b8d4e02: 8255374: Add a dropReturn MethodHandle combinator
• 1d0bd50: 8254758: Change G1ServiceThread to be task based
• 9a0cf58: 8255615: Zero: demote ZeroStack::abi_stack_available guarantee to assert
• 904561e: 8255719: Zero: on return path, check for pending exception before attempting to clear it
• 9bd836e: 8255744: Zero: handle JVM_CONSTANT_DynamicInError
• 36998b0: 8255716: AArch64: Regression: JVM crashes if manually offline a core
• 4107670: 8233562: [TESTBUG] Swing StyledEditorKit test bug4506788.java fails on MacOS
• 9a36747: 8255780: Remove unused overloads of VMError::report_and_die()
• c96a914: 8255662: ZGC: Unify nmethod closures in the heap iterator
• ... and 23 more: https://git.openjdk.java.net/jdk/compare/1769c48342b68712cb25b7df747201f46b8b9d54...master

Your commit was automatically rebased without conflicts.

Pushed as commit 93ef009.

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