[Bug tree-optimization/64992] More optimize opportunity

[ishiura-compiler at ml dot kwansei.ac.jp]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64992

--- Comment #4 from Ishiura Lab Compiler Team <ishiura-compiler at ml dot 
kwansei.ac.jp> ---
FYI, clang-3.6 -O3 seems to do the same optimization on "org.c" as well as on
"opt.c."