https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91131
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Known to work| |10.0
Known to fail|10.0 |
--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed on trunk sofar.
Note the non-optimal code-gen probably was a side-effect of us making
three volatile accesses out of one. On x86 I now see
main:
.LFB0:
.cfi_startproc
movl $0, Reg_A(%rip)
xorl %eax, %eax
movl $8, Reg_B(%rip)
movl $255, Reg_C(%rip)
movb $0, Reg_D(%rip)
movb $-1, Reg_E(%rip)
ret
as of using a packed structure the reason it might be problematic is that
this lowers its alignment to 1 byte. There are architectures that cannot
do unaligned accesses so when the bitfield spans more than one byte the
access might need to be decomposed. Using an aligned attribute in addition
to the packed attribute and aligning the structure appropriately would be
a solution to this issue.
