[Bug rtl-optimization/49088] Combine fails to properly handle zero-extension and signed int constant

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49088

--- Comment #6 from H.J. Lu <hjl.tools at gmail dot com> 2011-05-20 20:59:43 
UTC ---
Created attachment 24312
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24312
A patch

I am testing this patch.