[Bug tree-optimization/63641] Invalid shift leads to incorrect code on 32-bit system

[ian at airs dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63641

--- Comment #2 from Ian Lance Taylor <ian at airs dot com> ---
Created attachment 33805
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=33805&action=edit
sample patch

This patch seems to fix the problem, and the new tests still pass.  But I
haven't done full testing and I'm not entirely sure whether this is the right
approach.