Re: [PATCH, CHKP] Fix static const bounds creation in LTO

[Jan Hubicka <hubicka@ucw.cz>]

> 
> Thanks a lot for looking into it!  Seems originally I mostly got problems due to no DECL_WEAK for generated var, make_decl_one_only seems to work for my tests.  Will run more testing to make sure it's OK.  Here is a new patch version.  Is it OK?

Good ;)
> diff --git a/gcc/tree-chkp.c b/gcc/tree-chkp.c
> index 03f75b3..4daeab6 100644
> --- a/gcc/tree-chkp.c
> +++ b/gcc/tree-chkp.c
> @@ -1876,26 +1876,17 @@ chkp_add_bounds_to_call_stmt (gimple_stmt_iterator *gsi)
>  /* Return constant static bounds var with specified LB and UB
>     if such var exists in varpool.  Return NULL otherwise.  */
>  static tree
> -chkp_find_const_bounds_var (HOST_WIDE_INT lb,
> -			    HOST_WIDE_INT ub)
> +chkp_find_const_bounds_var (tree id)
>  {
> -  tree val = targetm.chkp_make_bounds_constant (lb, ub);
> -  struct varpool_node *node;
> -
> -  /* We expect bounds constant is represented as a complex value
> -     of two pointer sized integers.  */
> -  gcc_assert (TREE_CODE (val) == COMPLEX_CST);
> +  struct symtab_node *node = symtab_node::get_for_asmname (id);

Sadly I think this won't work on targets that adds prefix to assembler name,
like djgpp/mingw.
To obtain mangled assembler name you need to call
id = targetm.mangle_decl_assembler_name (decl, DECL_NAME (decl));
that in turn requires decl to already exist.  That is why I guess you may want
to just build the new var and see if already exists....

Honza
>  
> -  FOR_EACH_VARIABLE (node)
> -    if (POINTER_BOUNDS_P (node->decl)
> -	&& TREE_READONLY (node->decl)
> -	&& DECL_INITIAL (node->decl)
> -	&& TREE_CODE (DECL_INITIAL (node->decl)) == COMPLEX_CST
> -	&& tree_int_cst_equal (TREE_REALPART (DECL_INITIAL (node->decl)),
> -			       TREE_REALPART (val))
> -	&& tree_int_cst_equal (TREE_IMAGPART (DECL_INITIAL (node->decl)),
> -			       TREE_IMAGPART (val)))
> +  if (node)
> +    {
> +      /* We don't allow this symbol usage for non bounds.  */
> +      gcc_assert (node->type == SYMTAB_VARIABLE);
> +      gcc_assert (POINTER_BOUNDS_P (node->decl));
>        return node->decl;
> +    }
>  
>    return NULL;
>  }
> @@ -1907,37 +1898,34 @@ chkp_make_static_const_bounds (HOST_WIDE_INT lb,
>  			       HOST_WIDE_INT ub,
>  			       const char *name)
>  {
> +  tree id = get_identifier (name);
>    tree var;
> +  varpool_node *node;
>  
>    /* With LTO we may have constant bounds already in varpool.
>       Try to find it.  */
> -  var = chkp_find_const_bounds_var (lb, ub);
> +  var = chkp_find_const_bounds_var (id);
>  
>    if (var)
>      return var;
>  
> -  var  = build_decl (UNKNOWN_LOCATION, VAR_DECL,
> -		     get_identifier (name), pointer_bounds_type_node);
> +  var  = build_decl (UNKNOWN_LOCATION, VAR_DECL, id,
> +		     pointer_bounds_type_node);
>  
> -  TREE_PUBLIC (var) = 1;
>    TREE_USED (var) = 1;
>    TREE_READONLY (var) = 1;
>    TREE_STATIC (var) = 1;
>    TREE_ADDRESSABLE (var) = 0;
>    DECL_ARTIFICIAL (var) = 1;
>    DECL_READ_P (var) = 1;
> +  DECL_INITIAL (var) = targetm.chkp_make_bounds_constant (lb, ub);
> +  make_decl_one_only (var, DECL_ASSEMBLER_NAME (var));
>    /* We may use this symbol during ctors generation in chkp_finish_file
>       when all symbols are emitted.  Force output to avoid undefined
>       symbols in ctors.  */
> -  if (!in_lto_p)
> -    {
> -      DECL_INITIAL (var) = targetm.chkp_make_bounds_constant (lb, ub);
> -      DECL_COMDAT (var) = 1;
> -      varpool_node::get_create (var)->set_comdat_group (DECL_ASSEMBLER_NAME (var));
> -      varpool_node::get_create (var)->force_output = 1;
> -    }
> -  else
> -    DECL_EXTERNAL (var) = 1;
> +  node = varpool_node::get_create (var);
> +  node->force_output = 1;
> +
>    varpool_node::finalize_decl (var);
>  
>    return var;