https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82705
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Target| |x86_64-*-*, i?86-*-*
Status|UNCONFIRMED |NEW
Last reconfirmed| |2017-10-25
Version|unknown |7.2.1
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
sub/add are to align the stack according to the ABI.
The complication for the middle-end to perform the optimization is likely
the move of the argument slot pointer to the return slot pointer
(rdi to rax).
Confirmed.
