[Bug tree-optimization/63148] [4.8/4.9/5 Regression] r187042 causes auto-vectorization failure for X86 for -m32.

[doug.gilmore at imgtec dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63148

--- Comment #6 from Doug Gilmore <doug.gilmore at imgtec dot com> ---
> The input to the vectorizer is already bogus:
>
>   _12 = i.0_5 + 536870911;
>   _13 = global_data.b[_12];

Note that gimple out generated by the front end
is already problematic:

Before r187042:
  D.1747 = i.0 + -1;
With r187042:
  D.1747 = i.0 + 536870911;
Any idea what the intent of the changes in r187042 that transform
signed to unsigned constants?  To me, that is the problematic issue.