Where to attach backend builtin decl?

[Sa Liu]

FX,

Could you please check in this patch to mainline?

Thanks!
Sa
 
> With help from Jakub on IRC, I got the following working:
> 
> Index: f95-lang.c
> ===================================================================
> --- f95-lang.c  (revision 132578)
> +++ f95-lang.c  (working copy)
> @@ -723,7 +723,20 @@
>     implicit_built_in_decls[code] = decl;
>   }
> 
> +/* Look for a function decl with a given name.  */
> +tree
> +find_fndecl_toplevel (tree name)
> +{
> +  tree t;
> 
> +  for (t = global_binding_level->names; t; t = TREE_CHAIN (t))
> +    if (TREE_CODE (t) == FUNCTION_DECL && DECL_NAME (t) == name)
> +      return t;
> +
> +  return NULL_TREE;
> +}
> +
> +
>   #define DO_DEFINE_MATH_BUILTIN(code, name, argtype, tbase) \
>       gfc_define_builtin ("__builtin_" name "l", tbase##longdouble 
> [argtype], \
>                          BUILT_IN_ ## code ## L, name "l", true); \
> Index: trans.h
> ===================================================================
> --- trans.h     (revision 132578)
> +++ trans.h     (working copy)
> @@ -476,6 +476,7 @@
>   tree gfc_build_library_function_decl (tree, tree, int, ...);
> 
>   /* somewhere! */
> +tree find_fndecl_toplevel (tree);
>   tree pushdecl (tree);
>   tree pushdecl_top_level (tree);
>   void pushlevel (int);
> Index: trans-decl.c
> ===================================================================
> --- trans-decl.c        (revision 132578)
> +++ trans-decl.c        (working copy)
> @@ -1118,6 +1118,15 @@
>        to know that.  */
>     gcc_assert (!(sym->attr.entry || sym->attr.entry_master));
> 
> +  if (sym->attr.is_bind_c == 1
> +      && strncmp (sym->binding_label, "__builtin_", 10) == 0)
> +    {
> +      sym->backend_decl
> +       = find_fndecl_toplevel (get_identifier (sym->binding_label));
> +      if (sym->backend_decl)
> +       return sym->backend_decl;
> +    }
> +
>     if (sym->attr.intrinsic)
>       {
>         /* Call the resolution function to get the actual name.  This is
> 
> 
> The find_fndecl_toplevel() function does the job of getting decls 
> back from the global_binding_level given their identifier. It works 
> for the builtins I tried it with (like __builtin_sqrt), and I suppose 
> it should also work with your backend builtins. That saves us from 
> storing yet another namespace and using the already existing code. 
> Can you try it and see if it works for you?
> 
> And, in case it fails because the backend builtins are defined in a 
> contained binding level, we can changed the function to look from the 
> current binding level upwards, like this:
> 
> > +/* Look for a function decl with a given name.  */
> > +tree
> > +find_fndecl (tree name)
> > +{
> > +  struct binding_level *b;
> > +  tree t;
> > +
> > +  for (b = current_binding_level; b; b = b->level_chain)
> > +    for (t = b->names; t; t = TREE_CHAIN (t))
> > +      if (TREE_CODE (t) == FUNCTION_DECL && DECL_NAME (t) == name)
> > +       return t;
> > +
> > +  return NULL_TREE;
> > +}
> 
> (I have this code in my own tree because I use it for another patch, 
> the decl merging issue.) If the first one doesn't work, try this one.
> 
> > Following is the patch I have. Certainly in 
> > gfc_get_extern_function_decl() we need to add a check for standard 
> > intrinsics, before looking for backend intrinsics.
> 
> I think the above solution, which handles all intrinsics without 
> extra bookkeeping, is a better approach.
> 
> >
> FX
> 
> 
> -- 
> François-Xavier Coudert
> http://www.homepages.ucl.ac.uk/~uccafco/
>