[Bug middle-end/82885] memcpy does not propagate aliasing knowledge

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82885

--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> ---
gcc (illegally) generates some calls to memcpy(p,q,n) where p and q may be the
same pointer, although they mustn't overlap in any more complicated way. That
makes such an optimization problematic (although this memcpy generation seems
to happen at expansion time, so doing the optimization earlier might be ok).