Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merge jdk16 #1870

wants to merge 8 commits into from

Merge jdk16 #1870

wants to merge 8 commits into from


Copy link

@JesperIRL JesperIRL commented Dec 22, 2020

Forwardport JDK 16 -> JDK 17


  • Change must not contain extraneous whitespace
  • Commit message must refer to an issue
  • Change must be properly reviewed


$ git fetch pull/1870/head:pull/1870
$ git checkout pull/1870

rkennke and others added 8 commits Dec 21, 2020

Disable GCM hoisting of memory-writing nodes for irreducible CFGs. This prevents
GCM from wrongly "hoisting" stores into descendants of their original loop. Such
an "inverted hoisting" can happen due to CFGLoop::compute_freq()'s inaccurate
estimation of frequencies for irreducible CFGs.

Extend CFG verification code by checking that memory-writing nodes are placed in
either their original loop or an ancestor.

Add tests for the reducible and irreducible cases. The former was already
handled correctly before the change (the frequency estimation model prevents
"inverted hoisting" for reducible CFGs), and is just added for coverage.

This change addresses the specific miscompilation issue in a conservative way,
for simplicity and safety. Future work includes investigating if only the
illegal blocks can be discarded as candidates for GCM hoisting, and refining
frequency estimation for irreducible CFGs.

Reviewed-by: kvn, chagedorn
Reviewed-by: kvn, chagedorn
… and

Reviewed-by: amenkov, cjplummer
…RegistryNames/ on Windows

Reviewed-by: rriggs, msheppar, prr
Copy link

@bridgekeeper bridgekeeper bot commented Dec 22, 2020

👋 Welcome back jwilhelm! 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.

Copy link

@openjdk openjdk bot commented Dec 22, 2020

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

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

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


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 no new commits pushed to the master branch. If another commit should be pushed before you perform the /integrate command, your PR will be automatically rebased. If you prefer to avoid any potential 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.

Copy link

@openjdk openjdk bot commented Dec 22, 2020

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

  • compiler
  • hotspot
  • javadoc
  • 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.

Copy link

@mlbridge mlbridge bot commented Dec 22, 2020

Copy link
Member Author

@JesperIRL JesperIRL commented Dec 22, 2020


@openjdk openjdk bot closed this Dec 22, 2020
@openjdk openjdk bot added integrated and removed ready rfr labels Dec 22, 2020
Copy link

@openjdk openjdk bot commented Dec 22, 2020

@JesperIRL Pushed as commit f2bad3a.

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

@JesperIRL JesperIRL deleted the JesperIRL:forward_port_16_17 branch Dec 22, 2020
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
3 participants