Re: [Patch] OpenMP: Handle cpp_implicit_alias in declare-target discovery (PR96390)

[Jakub Jelinek <jakub@redhat.com>]

On Wed, Sep 23, 2020 at 03:52:12PM +0200, Tobias Burnus wrote:
> +  if (TREE_CODE (*tp) == FUNCTION_DECL)
>      {
> +      tree decl = *tp;
>        tree id = get_identifier ("omp declare target");
> -      if (!DECL_EXTERNAL (*tp) && DECL_SAVED_TREE (*tp))
> -	((vec<tree> *) data)->safe_push (*tp);
> -      DECL_ATTRIBUTES (*tp) = tree_cons (id, NULL_TREE, DECL_ATTRIBUTES (*tp));
>        symtab_node *node = symtab_node::get (*tp);
>        if (node != NULL)
>  	{
> +	  while (node->alias_target)
> +	    {
> +	      if (node->cpp_implicit_alias)
> +		node = node->get_alias_target ();
> +	      if (!omp_declare_target_fn_p (node->decl)
> +		  && !lookup_attribute ("omp declare target host",
> +					DECL_ATTRIBUTES (node->decl)))
> +		{
> +		  node->offloadable = 1;
> +		  DECL_ATTRIBUTES (node->decl)
> +		    = tree_cons (id, NULL_TREE, DECL_ATTRIBUTES (node->decl));
> +		}
> +	      node = symtab_node::get (node->alias_target);
> +	    }
> +	  if (node->cpp_implicit_alias)
> +	    node = node->get_alias_target ();

Almost, the problem is that node with node->cpp_implicit_alias isn't marked
then.  And, the
> +           if (node->cpp_implicit_alias)
> +             node = node->get_alias_target ();
in the while loop looks problematic, not sure if it is ever possible
to have both alias_target and cpp_implicit_alias set, but if it would be,
there is no guarantee that node->get_alias_target ()->alias_target must be
non-NULL.

What I really meant was:
> +	  while (node->alias_target)
> +	    {
> +	      if (!omp_declare_target_fn_p (node->decl)
> +		  && !lookup_attribute ("omp declare target host",
> +					DECL_ATTRIBUTES (node->decl)))
> +		{
> +		  node->offloadable = 1;
> +		  DECL_ATTRIBUTES (node->decl)
> +		    = tree_cons (id, NULL_TREE, DECL_ATTRIBUTES (node->decl));
> +		}
> +	      node = symtab_node::get (node->alias_target);
> +	    }
> +	  cgraph_node *new_node = node->get_ultimate_target ();
> +	  if (new_node != node)
> +	    {
> +	      while (node != new_node)
> +		{
> +		  if (!omp_declare_target_fn_p (node->decl)
> +		      && !lookup_attribute ("omp declare target host",
> +					    DECL_ATTRIBUTES (node->decl)))
> +		    {
> +		      node->offloadable = 1;
> +		      DECL_ATTRIBUTES (node->decl)
> +			= tree_cons (id, NULL_TREE, DECL_ATTRIBUTES (node->decl));
> +		    }
> +		  gcc_assert (node->alias && node->analyzed);
> +		  node = node->get_alias_target ();
> +		}
> +	    }

	Jakub