[Bug rtl-optimization/54585] stack space allocated but never used when calling functions that return structs in registers

[chip at pobox dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54585

--- Comment #3 from Chip Salzenberg <chip at pobox dot com> ---
It's worth it for cache reasons I believe.  The data cache works better you
don't spread out the stack data unnecessarily.  More concretely, if the stack
frame can entirely disappear then you also reduce the instruction count. 
That's fewer instructions to dispatch and less icache pressure.