http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50325
--- Comment #26 from rguenther at suse dot de <rguenther at suse dot de> 2011-12-01 11:23:41 UTC --- On Thu, 1 Dec 2011, iains at gcc dot gnu.org wrote: > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50325 > > --- Comment #23 from Iain Sandoe <iains at gcc dot gnu.org> 2011-12-01 > 10:10:10 UTC --- > there is nothing in the ABI doc: > > http://developer.apple.com/library/mac/#documentation/DeveloperTools/Conceptual/LowLevelABI/100-32-bit_PowerPC_Function_Calling_Conventions/32bitPowerPC.html#//apple_ref/doc/uid/TP40002438-SW20 > > that would suggest a different layout of bitfields in the two cases you cite. > > > For varargs and K&R style function calls - it can be that double/vect values > end up with a 4 byte alignment on the stack, when they are also passed in > regs. > (see PR 34311) - but I doubt that is relevant to this case. store_bit_field/extract_bit_field are not about bitfields in the C sense (despite their names). They are for setting/extracting a subset of bits. Any structure layout issue wrt bitfields has to be taken into account by the caller (so have any function-argument layout specialities). Richard.
