[Bug tree-optimization/79697] unused realloc(0, n) not eliminated

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79697

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
It makes sense to convert realloc(0, n) to just malloc and the rest just works.