[Bug middle-end/53623] [4.7/4.8 Regression] sign extension is effectively split into two x86-64 instructions

[hjl.tools at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53623

--- Comment #14 from H.J. Lu <hjl.tools at gmail dot com> ---
Created attachment 34767
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34767&action=edit
A backport patch for 4.8 branch

I am testing this patch now.