[Bug tree-optimization/88732] different results on -O0 and -O1, -O2, -O3, -Os

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88732

--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> ---
Why not read the documentation for that function?
"If x is 0, the result is undefined."