[Bug rtl-optimization/48696] Horrible bitfield code generation on x86

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48696

--- Comment #9 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-04-20 
15:41:09 UTC ---
Btw, the branch from the work "some time ago" created

show_bug:
.LFB2:
        movl    (%rdi), %eax
        andl    $-64, %eax
        movl    %eax, (%rdi)
        shrl    $6, %eax
        movzwl  %ax, %eax
        ret

for your testcase.