PING [Patch][Middle-end]Add -fzero-call-used-regs=[skip|used-gpr|all-gpr|used|all]

[Segher Boessenkool]

On Fri, Sep 04, 2020 at 10:34:23AM -0700, H.J. Lu wrote:
> > You probably have to do this for every target separately?  But it is not
> > enough to handle it in the epilogue, you also need to make sure it is
> > done on every path that returns *without* epilogue.
> 
> This feature is designed for normal return with epilogue.

Very many normal returns do *not* pass through an epilogue, but are
simple_return.  Disabling that is *much* more expensive than that 2%.


Segher