[libc-commits] [PATCH] D118157: [libc] Improve hypotf performance with different algorithm correctly rounded to all rounding modes.

Paul Zimmermann via Phabricator via libc-commits libc-commits at lists.llvm.org
Fri Jan 28 01:36:58 PST 2022

zimmermann6 added a comment.

I'm still running semi-exhaustive tests, it takes some time. I wonder whether a full exhaustive test is possible, by comparing the LLVM implementation with the code from Alexei at https://core-math.gitlabpages.inria.fr/. On a 64-core machine (Intel Xeon Gold 6130 @ 2.10GHz), it takes 4.6s to check 2^33 pairs (x,y). If one tests only positive x,y and x>=y, as exhaustive comparison would have to check 2^61 pairs for each rounding mode, which would take less than 1.5 month using 10000 such machines. This would not be a proof, but the probability that both codes are wrong for the same inputs and give exactly the same wrong answer is quite small.

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