[Bug tree-optimization/54295] [4.7 regression] Widening multiply-accumulate operation uses wrong value extension

[rearnsha at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54295

--- Comment #1 from Richard Earnshaw <rearnsha at gcc dot gnu.org> 2012-08-17 
12:47:35 UTC ---
Created attachment 28042
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=28042
Testcase