https://gcc.gnu.org/bugzilla/show_bug.cgi?id=76774
--- Comment #4 from Peter Sewell <Peter.Sewell at cl dot cam.ac.uk> --- (In reply to Andrew Pinski from comment #3) > What code were you expecting anyways? I hadn't noticed how recent the other-size LL/SC were. But then I would have expected a 4-byte representation for _Atomic(_Bool) on the older machines, to minimise the amount of code between the lwarx and stwcx; would that have some other disadvantage? I don't think the code you've got is functionally wrong on normal h/w. We noticed this running in a semantics-based emulator that's very picky about reading from uninitialised memory, but on normal h/w the extra memory will AFAICS always be mapped and be within the same reservation granule.