JDK-8369881 : C2: Unexpected node in SuperWord truncation: ReverseBytesS, ReverseBytesUS
  • Type: Bug
  • Component: hotspot
  • Sub-Component: compiler
  • Affected Version: 26
  • Priority: P3
  • Status: Resolved
  • Resolution: Fixed
  • Submitted: 2025-10-15
  • Updated: 2025-10-21
  • Resolved: 2025-10-16
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 26
26 b20Fixed
Related Reports
Causes :  
JDK-8350177 - C2 SuperWord: Integer.numberOfLeadingZeros, numberOfTrailingZeros, reverse and bitCount have input types wrongly truncated for byte and short
Description
In production, this behaves safe, but in debug, we find a missing case.

Very easy to reproduce:

java Test.java
Comments
Changeset: aa194c6a Branch: master Author: Emanuel Peter <epeter@openjdk.org> Date: 2025-10-16 06:45:10 +0000 URL: https://git.openjdk.org/jdk/commit/aa194c6a5a21aca64d454e4c5eeed1464c8f190b
16-10-2025
A pull request was submitted for review. Branch: master URL: https://git.openjdk.org/jdk/pull/27819 Date: 2025-10-15 08:46:23 +0000
15-10-2025
ILW = Same as JDK-8362979 = P3
15-10-2025