On Mon, Feb 13, 2023 at 12:41:48PM +0000, Richard Biener wrote:
> > Could we e.g. prevent turning such indirect calls into direct calls?
>
> We do exactly have gimple_call_fntype and gimple_call_ctrl_altering_p
> to not require special-casing indirect to direct call promotion here.
Ah, so if we make returns_twice apply to function types, then we could
just compare if gimple_call_fntype has also returns_twice and if not, not
consider it actually returns_twice.
> > Anyway, notice_special_calls is called in various spots, not just DCE,
> > wouldn't it be better to simply not set calls_setjmp flag in there if
> > the current function already has cfg and the call isn't ctrl altering?
>
> I thought about changing gimple_call_flags instead, filtering out
> ECF_RETURNS_TWICE. I just didn't make up my mind on what
> property to key at (and to require 'cfun' to be set to query it).
> But sure, changing notice_special_calls also works - the only
> other relevant caller is the inliner I think, and that could be
> replaced by caller |= callee of the two flags tracked instead of
> re-scanning each inlined stmt.
>
> Would you be happy with changing notice_special_calls, dropping the
> DCE hunk but keeping the cfgexpand/calls.cc hunks?
I think so.
Jakub
