Re: PR84229 part 1: Avoid cloning of functions that calls va_arg_pack

[Jan Hubicka <hubicka@ucw.cz>]

> On Wed, Feb 21, 2018 at 08:09:28PM +0100, Jan Hubicka wrote:
> > --- ipa-cp.c	(revision 257844)
> > +++ ipa-cp.c	(working copy)
> > @@ -630,6 +630,24 @@ determine_versionability (struct cgraph_
> >        reason = "calls comdat-local function";
> >      }
> >  
> > +  /* Functions calling BUILT_IN_VA_ARG_PACK and BUILT_IN_VA_ARG_PACK_LEN
> > +     works only when inlined.  Cloning them may still lead to better code
> 
> s/works/work/
> 
> > +     becuase ipa-cp will not give up on cloning further.  If the function is
> 
> s/becuase/because/
> 
> > +     external this however leads to wrong code becuase we may end up producing
> 
> s/becuase/because/

Thanks, fixed.

> 
> > +     offline copy of the function.  */
> > +  if (DECL_EXTERNAL (node->decl))
> > +    for (cgraph_edge *edge = node->callees; !reason && edge;
> > +	 edge = edge->next_callee)
> > +      if (DECL_BUILT_IN (edge->callee->decl)
> > +	  && DECL_BUILT_IN_CLASS (edge->callee->decl) == BUILT_IN_NORMAL)
> > +        {
> > +	  if (DECL_FUNCTION_CODE (edge->callee->decl) == BUILT_IN_VA_ARG_PACK)
> > +	    reason = "external function which calls va_arg_pack";
> > +	  if (DECL_FUNCTION_CODE (edge->callee->decl)
> > +	      == BUILT_IN_VA_ARG_PACK_LEN)
> > +	    reason = "external function which calls va_arg_pack_len";
> > +        }
> > +
> >    if (reason && dump_file && !node->alias && !node->thunk.thunk_p)
> >      fprintf (dump_file, "Function %s is not versionable, reason: %s.\n",
> >  	     node->dump_name (), reason);
> 
> Do you have a testcase for this, or is it LTO with too large input?

There is reduced testcase in the PR which probably should be rejected by C
frontend because it is uses va_arg_pack on non-variadic function.
I plan to send additional patches and then come with a testcase (because current
one should be early inlined and thus it will stop testing ipa-cp)

Honza