http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50521
--- Comment #10 from Tomohiro Kashiwada <kikairoya at gmail dot com> 2011-10-28 08:13:31 UTC --- (In reply to comment #9) > http://infocenter.arm.com/help/topic/com.arm.doc.ihi0042d/IHI0042D_aapcs.pdf > section 7.1.7.5. Thanks, I see. On ARM ABI, reading or writing to volatile-bitfields should not cause double access and regardless of volatileness, access should be aligned as container's type. I think that to avoid double access needs treatment of volatile object.