8357968: RISC-V: Interpreter volatile reference stores with G1 are not sequentially consistent

[feilongjiang]

Fixes RISC-V memory ordering problem.
This patch is not clean because JDK-8293290 adds a third temporary register to store_heap_oop, which is introduced in JDK20.
In JDK17, do_oop_store also clobbers the same x13 as in mailine. The current fix is similar to aarch64 in mainline, but puts the flags in x15 instead, to avoid the clobber of the volatile bits.

Additional testing:

• linux-riscv64 server release, jcstress RefDekker test now passes
• linux-riscv64 server release, Tier1-3

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8357968 needs maintainer approval

Issue

• JDK-8357968: RISC-V: Interpreter volatile reference stores with G1 are not sequentially consistent (Bug - P4 - Approved)

Reviewers

• Robbin Ehn (@robehn - Committer)
• Fei Yang (@RealFYang - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk17u-dev.git pull/3678/head:pull/3678
$ git checkout pull/3678

Update a local copy of the PR:
$ git checkout pull/3678
$ git pull https://git.openjdk.org/jdk17u-dev.git pull/3678/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 3678

View PR using the GUI difftool:
$ git pr show -t 3678

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk17u-dev/pull/3678.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back fjiang! 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]

@feilongjiang 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:

8357968: RISC-V: Interpreter volatile reference stores with G1 are not sequentially consistent

Reviewed-by: rehn, fyang

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 6 new commits pushed to the master branch:

• fb0a796: 8315505: CompileTask timestamp printed can overflow
• 183b9a0: 8314978: Multiple server call from connection failing with expect100 in getOutputStream
• 2a9bba2: 8336499: Failure when creating non-CRT RSA private keys in SunPKCS11
• ... and 3 more: https://git.openjdk.org/jdk17u-dev/compare/34f76e39b4ed9984e157c932d8145f7adfeeed98...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.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@robehn, @RealFYang) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

[openjdk]

This backport pull request has now been updated with issue from the original commit.

[mlbridge]

Webrevs

• 00: Full (3cdd9a44)

[feilongjiang]

@robehn, would you please take a look?

[robehn]

Looks good!

[RealFYang]

Looks good.

[openjdk]

⚠️ @feilongjiang This change is now ready for you to apply for maintainer approval. This can be done directly in each associated issue or by using the /approval command.

[feilongjiang]

/approval request Fixes the corner case in RISC-V interpreter, manifests as memory model problem.
Same issue exists in jdk17u repo as well. And the bug is reproducible with jcstress RefDekker test with jdk17u.
Backport is not clean. This is a RISC-V specific change, 17u version differs a bit from mainline version, see 17u PR.
Tier1-3 tested on linux-riscv64 platform. jcstress RefDekker test passes with this backport.

[openjdk]

@feilongjiang
8357968: The approval request has been created successfully.

[feilongjiang]

@robehn @RealFYang -- Thanks!
/integrate

[openjdk]

@feilongjiang
Your change (at version 3cdd9a4) is now ready to be sponsored by a Committer.

[RealFYang]

/sponsor

[openjdk]

Going to push as commit 76e1329.
Since your change was applied there have been 6 commits pushed to the master branch:

• fb0a796: 8315505: CompileTask timestamp printed can overflow
• 183b9a0: 8314978: Multiple server call from connection failing with expect100 in getOutputStream
• 2a9bba2: 8336499: Failure when creating non-CRT RSA private keys in SunPKCS11
• ... and 3 more: https://git.openjdk.org/jdk17u-dev/compare/34f76e39b4ed9984e157c932d8145f7adfeeed98...master

Your commit was automatically rebased without conflicts.

[openjdk]

@RealFYang @feilongjiang Pushed as commit 76e1329.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.