Re: [PATCH] Make redirection only for target_clones: V2 (PR ipa/85329).

[Martin Liška <mliska at suse dot cz>]

On 04/12/2018 03:46 PM, Jan Hubicka wrote:
> > 2018-04-12  Martin Liska  <mliska@suse.cz>
> >
> > 	PR ipa/85329
> > 	* multiple_target.c (create_dispatcher_calls): Set apostrophes
> > 	for target_clone error message.
> > 	(separate_attrs): Add new argument and check for an emptry
> > 	string.
> > 	(expand_target_clones): Handle it.
> > 	(ipa_target_clone): Make redirection just for target_clones
> > 	functions.
> >
> > gcc/testsuite/ChangeLog:
> >
> > 2018-04-12  Martin Liska  <mliska@suse.cz>
> >
> > 	PR ipa/85329
> > 	* g++.dg/ext/pr85329.C: New test.
> > 	* gcc.target/i386/mvc12.c: New test.
> > @@ -413,7 +426,11 @@ expand_target_clones (struct cgraph_node *node, bool definition)
> >     tree attributes = make_attribute ("target", "default",
> >   				    DECL_ATTRIBUTES (node->decl));
> >     DECL_ATTRIBUTES (node->decl) = attributes;
> > +  DECL_COMDAT (node->decl) = 0;
> > +  DECL_WEAK (node->decl) = 0;
> > +  DECL_ARTIFICIAL (node->decl) = 1;
> >     node->local.local = false;
> > +  node->set_comdat_group (NULL);
>
> If you make C++ inline and get the idea to use target cloning attribute on this,
> this will likely lead to link error if you compile multiple files because you
> turn comdat to non-comdat.
>
> For comdats this woudl effectivly need to become C++ abi extension and we would
> need to define comdat sections for these.  Perhaps easiest way is to simply
> reject the attribute on comdats and probaby also extern functions?
>
> Otherwise patch looks OK.
> Honza

And Honza also asked me for description what has changes in between GCC 7.x and current trunk.
There are test-cases that illustrate that:

./gcc/testsuite/gcc.target/i386/mvc10.c
./gcc/testsuite/gcc.target/i386/mvc11.c
./gcc/testsuite/gcc.target/i386/mvc5.c
./gcc/testsuite/gcc.target/i386/mvc7.c
./gcc/testsuite/gcc.target/i386/pr80732.c
./gcc/testsuite/gcc.target/i386/pr81214.c

Martin