Tom Eccles d16ecad968
[flang] Disable noalias by default (#142128)
With these enabled we see a 70% performance regression for exchange2_r
on neoverse-v1 (aws graviton 3) using `-mcpu=native -Ofast -flto`. There
is also a smaller regression on neoverse-v2.

This appears to be because function specialization is no longer kicking
in during LTO for digits_2. This can be seen in the output executable:
previously it contained specialized copies of the function with names
like `_QMbrute_forcePdigits_2.specialized.4`. Now there are no names
like this.

The bug is not in flang - instead in the function specialization pass -
but due to the size of the regression I would like to request that this
is disabled until function specialization has been fixed.
2025-05-30 17:35:41 +01:00
..