[Bug c/57157] Poor optimization of portable rotate idiom

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57157

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 30075
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30075&action=edit
/tmp/gcc49-pr57157.patch

Untested tiny i386 improvement, instead of roll $31, %eax we can emit
rorl %eax which is shorter.