JDK-8324688 : C2: Disable ReduceAllocationMerges by default
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 22
  • Priority: P2
  • Status: Closed
  • Resolution: Fixed
  • Submitted: 2024-01-25
  • Updated: 2024-02-02
  • Resolved: 2024-01-26
The Version table provides details related to the release that this issue/RFE will be addressed.

Unresolved : Release in which this issue/RFE will be addressed.
Resolved: Release in which this issue/RFE has been resolved.
Fixed : Release in which this issue/RFE has been fixed. The release containing this fix may be available for download as an Early Access Release or a General Availability Release.

To download the current JDK release, click here.
JDK 22
22 b34Fixed
Related Reports
Duplicate :  
JDK-8287061 - Support for rematerializing scalar replaced objects participating in allocation merges
Duplicate :  
JDK-8322854 - Incorrect rematerialization of scalar replaced objects in C2
Description
Due to several recent bug reports after JDK-8287061 (latest one JDK-8322854), we've decided it's best to disable ReduceAllocationMerges by default for JDK 22 which disables the features of JDK-8287061.
Comments
Changeset: b7f38fc5 Author: Christian Hagedorn <chagedorn@openjdk.org> Date: 2024-01-26 14:25:49 +0000 URL: https://git.openjdk.org/jdk22/commit/b7f38fc54f7121e518db1e19c1ca7e80744b6798
26-01-2024
Thanks Vladimir for the approval!
26-01-2024
Fix request for JDK 22 approved.
25-01-2024
A pull request was submitted for review. URL: https://git.openjdk.org/jdk22/pull/97 Date: 2024-01-25 10:27:37 +0000
25-01-2024
Fix Request: There have been several bug reports after the integration of JDK-8287061 which is a new improvement integrated in JDK 22. Since we are late in the release and we are still discovering issues (latest one being JDK-8322854), we request to disable JDK-8287061 by setting ReduceAllocationMerges to false by default in JDK 22.
25-01-2024
ILW = Several crashes after JDK-8287061, recent regression but intermittently observed, use -XX:-ReduceAllocationMerges = HMM = P2
25-01-2024