https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115954
--- Comment #5 from Wilco <wilco at gcc dot gnu.org> --- (In reply to Richard Biener from comment #2) > (In reply to Richard Biener from comment #1) > > Not sure what the x86 psABI says here (possibly nothing for aggregate > > _Atomic). > > It doesn't consider _Atomic [influencing the ABI] at all. > > Note I think your test queries actual object alignment which a compiler > can of course increase vs. what the ABI requires as minimum alignment, > you should possibly cross-check with alignof/sizeof of the type. > > On x86 clang returns size 8 and align 8 for the atomic A7 type (GCC does > not). I tried using the type for sizeof/alignof, and it returns the same values. So GCC overaligns structs that are an exact power of 2.
