[Bug c/50521] -fstrict-volatile-bitfields is not strict

[henrik at henriknordstrom dot net]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50521

--- Comment #7 from Henrik Nordström <henrik at henriknordstrom dot net> 2011-10-28 01:59:34 UTC ---
Right.  r171347 seem to be about fetches from bitfields while this change is
about stores?

An interesting test would be 

  bitfield.bits.a = bitfield.bits.c

which should load the int to a register, load the int again to another
register, copy c to a between them and store the result.  I guess the double
load may be optimized away as it's an sideeffect of the aassignment.