Per VognsenWeird FUD by Phoronix about LTO builds since Mesa is apparently turning off their LTO builds due to "impossible to reproduce bugs that only happen in LTO builds". I'd like to get other people's take, but I'm assuming what's actually happening is that like with -O1 vs -O3, optimizing across translation units is exposing latent UB bugs (or much less likely, latent compiler bugs not directly related to LTO), and it's not that the LTO pass itself is buggy.
Andrea (Drea) Tamar Pinski@pervognsen at one point Mesa had strict aliasing turned off but they turned it back in recent years so that might be still an issue.
A good example of alaising issue and lto. I fixed a strict aliasing issue in gcc sources in 2011 (PR48981) which was exposed by lto, just happens spec 2017 chose a gcc that was older than that too and every once in a while (like last year), we get a report of gcc in spec failing with lto if using strict aliasing but only with the new enough gcc.
It is just funny how I fixed it almost 15 years ago now too.