------- Comment #2 from xinping dot huang at gmail dot com 2010-05-24 13:51 ------- Subject: Re: Strange behavior on bit fields sructures.
My gcc 4.4.4 generate the correct binary and get the correct result even with -O3 option. Wesley 2010/5/24 dennis at conus dot info <gcc-bugzi...@gcc.gnu.org>: > > > ------- Comment #1 from dennis at conus dot info 2010-05-24 13:30 ------- > The code 4.4.1 x86 generating (with -O3 option) for bswap() function I > mentioned earlier is strange too: > > > ; bswap(unsigned int) > public _Z5bswapj > _Z5bswapj proc near > > var_4 = dword ptr -4 > arg_0 = dword ptr 8 > > push ebp > mov ebp, esp > sub esp, 10h > mov eax, [ebp+arg_0] > mov edx, eax > sar edx, 18h > mov byte ptr [ebp+var_4], dl > mov edx, eax > shr edx, 10h > mov byte ptr [ebp+var_4+1], dl > movsx edx, ah > mov byte ptr [ebp+var_4+3], al > mov eax, [ebp+var_4] ; returning var_4 > mov byte ptr [ebp+var_4+2], dl ; set last byte to var_4 > leave > retn > _Z5bswapj endp > > > -- > > > http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44260 > > -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44260
