[Bug tree-optimization/31178] VRP can infer a range for b in a >> b and a << b

[amacleod at redhat dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=31178

--- Comment #9 from Andrew Macleod <amacleod at redhat dot com> ---
Seems like it may expose a problem in gcc.target/i386/sse2-v1ti-shift-3.c as
well:

 for (i=0; i<128; i++) {
<...>
    if ((ti)rotr_v1ti(ut,i) != (ti)rotr_ti(x,i))
      __builtin_abort();
    if ((ti)rotl_v1ti(ut,i) != (ti)rotl_ti(x,i))

And those are defined:

uv1ti rotr_v1ti(uv1ti x, unsigned int i) { return (x >> i) | (x << (128-i)); }
uv1ti rotl_v1ti(uv1ti x, unsigned int i) { return (x << i) | (x >> (128-i)); }

so when i is 0, they can perform a shift of 128 on a 128 bit object.