If the ++ or -- operator is used on a bitfield, the addition or subtraction is done with the size of the bitfield. So code like: struct { int f:3; } s; ... s->f++; will generate intermediate code like: add.3 %r <- %a, $1 This is not incorrect from the IR point of view but CPUs have only register-sized instructions, like 'add.32'. So, these odd-sized instruction have one or two implicit masking/extend that should better make explicit. Fix this by casting to and from the base type when these operators are used on bitfields. Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>