[Bug target/119628] Need better mechanisms to manage register saves in callee for tail calls

[hjl.tools at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119628

--- Comment #3 from H.J. Lu <hjl.tools at gmail dot com> ---
(In reply to ak from comment #2)
> The existing attributes could just handle this case?

Caller needs to know what registers are saved by callee.  But caller doesn't
know what ISAs are used by callee.