8290451: Incorrect result when switching to C2 OSR compilation from C1

[rwestrel]

In BadStateAtLongCmp.test(), the field increment is between the lcmp
and iflt bytecodes that implement the loop exit condition (handcrafted
bytecodes required as such a sequence is not generated by javac). When
compiled by C1, lcmp+iflt is canonicalized to a single If and it
captures the state of the lcmp bytecode. Tiered compilation attaches
the state to a deoptimization call to switch to an OSR
compilation. That state causes the field increment to be reexecuted
when the switch to a C2 method occurs at the backbranch. Proposed fix
is to use the state at the iflt instead.

---

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

Issue

• JDK-8290451: Incorrect result when switching to C2 OSR compilation from C1

Reviewers

• Tobias Hartmann (@TobiHartmann - Reviewer)
• Vladimir Kozlov (@vnkozlov - Reviewer)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk pull/9938/head:pull/9938
$ git checkout pull/9938

Update a local copy of the PR:
$ git checkout pull/9938
$ git pull https://git.openjdk.org/jdk pull/9938/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 9938

View PR using the GUI difftool:
$ git pr show -t 9938

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/9938.diff

[bridgekeeper]

👋 Welcome back roland! 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]

@rwestrel The following label will be automatically applied to this pull request:

• hotspot-compiler

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

[mlbridge]

Webrevs

• 01: Full - Incremental (d0a821aa)
• 00: Full (61be28c2)

[TobiHartmann]

Looks good to me.

[TobiHartmann]

Please use an older bytecode version to simplify backports.

[rwestrel]

Done (with the class file version for jdk 8 now)

[openjdk]

@rwestrel 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:

8290451: Incorrect result when switching to C2 OSR compilation from C1

Reviewed-by: thartmann, kvn

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 88 new commits pushed to the master branch:

• bc6ac6f: 8292968: java.net.ContentHandler's javadoc has a broken reference
• e016363: 8293007: riscv: failed to build after JDK-8290025
• 9424d6d: 8293012: ConstantPool::print_on can crash if _cache is NULL
• 40b0ed5: 8292891: ifdef-out some CDS-only functions
• adb3d4f: 8292694: x86_64 c2i/i2c adapters may use more stack space than necessary
• 30def49: 8292769: [JVMCI] OutOfMemoryError thrown when attaching the libgraal isolate causes HotSpot to crash.
• a88a9e3: 8291466: C2: assert(false) failed: infinite loop in PhaseIterGVN::transform_old with -XX:+StressIGVN
• d5167a9: 7189422: [macosx] Submenu's arrow have a wrong position
• 512fee1: 8292972: Initialize fields if CodeBlobIterator shortcuts without heaps
• a476ec5: 8292983: ModuleReferenceImpl.computeHash should record algorithm for cache checks
• ... and 78 more: https://git.openjdk.org/jdk/compare/79597f1ea6844f374beeeba219719cd9d5fe7d03...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.

[rwestrel]

Looks good to me.

Thanks for the review.

[vnkozlov]

Ok.

[rwestrel]

@vnkozlov thanks for the review

[rwestrel]

/integrate

[openjdk]

Going to push as commit afa5d4c.
Since your change was applied there have been 88 commits pushed to the master branch:

• bc6ac6f: 8292968: java.net.ContentHandler's javadoc has a broken reference
• e016363: 8293007: riscv: failed to build after JDK-8290025
• 9424d6d: 8293012: ConstantPool::print_on can crash if _cache is NULL
• 40b0ed5: 8292891: ifdef-out some CDS-only functions
• adb3d4f: 8292694: x86_64 c2i/i2c adapters may use more stack space than necessary
• 30def49: 8292769: [JVMCI] OutOfMemoryError thrown when attaching the libgraal isolate causes HotSpot to crash.
• a88a9e3: 8291466: C2: assert(false) failed: infinite loop in PhaseIterGVN::transform_old with -XX:+StressIGVN
• d5167a9: 7189422: [macosx] Submenu's arrow have a wrong position
• 512fee1: 8292972: Initialize fields if CodeBlobIterator shortcuts without heaps
• a476ec5: 8292983: ModuleReferenceImpl.computeHash should record algorithm for cache checks
• ... and 78 more: https://git.openjdk.org/jdk/compare/79597f1ea6844f374beeeba219719cd9d5fe7d03...master

Your commit was automatically rebased without conflicts.

[openjdk]

@rwestrel Pushed as commit afa5d4c.

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