[Bug middle-end/41455] memcpy not tail called if it's a struct assignment

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41455

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
We could do that I suppose.  Of course memcpy will expand to alias-set zero
block copies while aggregate assignment can use better info.

So in the end this means doing full block-copy expansion on GIMPLE rather than
on RTL.  Which sounds messy / impossible given stuff like rep; movb;

Another option is to not use __builtin_memcpy for aggregate assignments but
some internal function call that we can hand extra parameters (for aliasing).