[Bug tree-optimization/67351] Missed optimisation on 64-bit field compared to 32-bit

[hs.naveen2u at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67351

--- Comment #8 from hs.naveen2u at gmail dot com ---
Patch that implements the optimization referred by Richard and Andrew.
https://gcc.gnu.org/ml/gcc-patches/2015-09/msg00014.html