For the integer shift ops, since the Src1 operand is forced
to be an immediate or register (cl), it should be legal to
have Dest+Src0 be either register or memory. However, we
are currently only using the register form. It might be the
case that shift w/ Dest+Src0 as mem are less optimized
on some micro-architectures though, since it has to load,
shift, and store all in one operation, but I'm not sure.

BUG=none
R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/622113002