> The choice appears to be to continue to have broken volatile bitfields > on ARM with no way for users to make them conform to the ABI, or to > change things so that they conform to the ABI if you specify > -fstrict-volatile-bitfields explicitly and to the C/C++ standard by > default, without that option.
I can't speak for ARM, but for the other targets (for which I wrote the original patch), the requirement is that volatile bitfield accesses ALWAYS be in the mode of the type specified by the user. If the user says "int x:8;" then SImode (assuming 32-bit ints) must always be used, even if QImode could be used. The reason for this is that volatile bitfields are normally used for memory-mapped peripherals, and accessing peripheral registers in the wrong mode leads to incorrect operation.
