RFR: 8346914: UB issue in scalbnA

[Andrew Haley]

On Thu, 5 Jun 2025 07:48:03 GMT, David Holmes <dholmes at openjdk.org> wrote:

> Second, finding the math routines and the arguments thereto which actually reach this function is also difficult. I have found 3 tests only that hit the `scalbnA` function at the point where the potential overflow occurs, but beyond that I cannot determine what arguments will cause the different code paths to be taken. Consequently the only testing I could do here was to make a copy of the original `scalbnA` function and then place a check in the callers that the old and new code produced the same result. Again how much coverage this actually gave is not known. That test code still remains in the PR as the initial commit.

I'm somewhat perplexed by this. Should I conclude that you have never succeeded in triggering the UB, and that you do not know if UB ever occurs?

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

PR Comment: https://git.openjdk.org/jdk/pull/25656#issuecomment-2944064370