[Bug tree-optimization/58277] wrong code at -O3 (affecting 4.7, 4.8, and trunk)

[su at cs dot ucdavis.edu]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58277

--- Comment #1 from Zhendong Su <su at cs dot ucdavis.edu> ---
Created attachment 30725
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30725&action=edit
testcase