[Bug tree-optimization/88598] simplification of multiplication by 1 or 0 fails

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88598

--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> ---
-funroll-loops helps (I expect that's what llvm does).
float j[5] = {}; also helps. We should probably simplify {0,0,...} to {}, but
then we would still be missing the optimization for {1,1,...} where we would
like to notice that any read can only yield 1.