RFR: 8344026: [s390x] ubsan failure: signed integer overflow in c1_LIRGenerator_s390.cpp

[Martin Doerr]

On Fri, 15 Nov 2024 10:04:51 GMT, Amit Kumar <amitkumar at openjdk.org> wrote:

> This PR adds `c > 0 && c < max_jint` check in c1_LIRGenerator_s390.cpp. Please look JBS for more info.

One more remark: Your current solution restricts the scope of the optimization while the unsigned solution (`is_power_of_2((juint)c + 1)`,  `log2i_exact((juint)c + 1)`, ...) only fixes UB. I don't think optimizing multiplication by these special values is particularly important. So, I'm ok with either version.

-------------

PR Comment: https://git.openjdk.org/jdk/pull/22144#issuecomment-2479013713