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.
Luke Wren@pervognsen Yeah, the only time I have actually seen compiler bugs with LTO was when we were LTOing a mixture of v8-M Main and Base in the RP2350 ROM. Even that was ICEs instead of miscompiles.
That said I am currently working with a large embedded firmware codebase that has issues under LTO, and it's pretty annoying to track down given there is no way of running it off-target, so things like ubsan are not an option.
LTO also makes the disassembly way more annoying to read, which unfortunately I care about quite a bit if I'm down in the weeds doing hardware debug.