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

[Amit Kumar]

On Fri, 15 Nov 2024 11:50:04 GMT, Martin Doerr <mdoerr at openjdk.org> wrote:

>>>With your code strength_reduce_multiply will no longer be called with negative c preventing possible optimizations inside of it.
>> 
>> My thoughts are that even if `strength_reduce_multiply` is being called with `-ve` values. It's almost doing nothing. At the end we are falling back to this code: 
>> 
>>         // we couldn't strength reduce so just emit the multiply
>>         if (!did_strength_reduce) {
>>           __ mul(left_op, right_op, result_op);
>>         }
>
> I didn't get your point. Some platform owners may want to use `strength_reduce_multiply` for more cases in the future.

That is possible. Thanks for the suggestion. I have reverted the commit :-)

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PR Review Comment: https://git.openjdk.org/jdk/pull/22144#discussion_r1843700689