On Tue, Apr 05, 2022 at 04:05:22PM +0200, Peter Zijlstra wrote: > On Tue, Apr 05, 2022 at 01:51:30PM +0100, Mark Rutland wrote: > > Hi all, > > > > [adding kernel folk who work on asm stuff] > > > > As a heads-up, GCC 12 (not yet released) appears to erroneously optimize away > > calls to functions with volatile asm. Szabolcs has raised an issue on the GCC > > bugzilla: > > > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105160 > > > > ... which is a P1 release blocker, and is currently being investigated. > > > > Jemery originally reported this as an issue with {readl,writel}_relaxed(), but > > the underlying problem doesn't have anything to do with those specifically. > > > > I'm dumping a bunch of info here largely for posterity / archival, and to find > > out who (from the kernel side) is willing and able to test proposed compiler > > fixes, once those are available. > > > > I'm happy to do so for aarch64; Peter, I assume you'd be happy to look at the > > x86 side? > > Sure.. FWIW, compiler explorer now have a trunk build with the fix, and my x86-64 example now gets compiled to something which looks correct: https://godbolt.org/z/cveff9hq5 Thanks, Mark.
