Re: PR tree-optimization/45522 (missed constand folding in VRP)

[Richard Guenther <rguenther at suse dot de>]

On Sat, 4 Sep 2010, Jan Hubicka wrote:

> Hi
> this patch fixes missed folding of tree_code_type[6] into 2 in the testcase
> attached.  The problem is that the constant is discovered by VRP, not CCP and
> gimple_fold makes no attempt to fold the constant vars references into
> constants except for string.
> 
> Moving code folding strings into fold_const_aggregate_ref is also needed
> to avoid one missed constant folding during Ada bootstrap I don't know how
> to produce testcase for.
> 
> Bootstrapped/regtested x86_64-linux, OK?

Ok.

Thanks,
Richard.

> Honza
> 
> /* { dg-do compile } */
> /* { dg-options "-O2 -fdump-tree-optimized" } */
> typedef const union tree_node *const_tree;
> typedef struct
> {
> }
> double_int;
> double_int double_int_zext (double_int, unsigned);
> enum tree_code
> { ERROR_MARK, IDENTIFIER_NODE, TREE_LIST, BLOCK, ENUMERAL_TYPE, BOOLEAN_TYPE,
>     INTEGER_TYPE, ARRAY_TYPE, INTEGER_CST, VAR_DECL, PARM_DECL, RESULT_DECL,
>   };
> enum tree_code_class
> { tcc_exceptional, tcc_constant, tcc_type, tcc_declaration, tcc_reference, };
> struct tree_base
> {
>   __extension__ enum tree_code code:16;
>   unsigned unsigned_flag:1;
> };
> struct tree_type
> {
>   unsigned int precision:10;
>   union tree_type_symtab
>   {
>   } symtab;
> };
> union tree_node
> {
>   struct tree_base base;
>   struct tree_type type;
> };
> const enum tree_code_class tree_code_type[] =
> { tcc_exceptional, 1, 0, 0, 0, 0, 2, };
> 
> int_fits_type_p (const_tree c, const_tree type)
> {
>   double_int dc, dd;
>   {
>     if (((enum tree_code) (type)->base.code) == INTEGER_TYPE && ((
> 								   {
> 								   __typeof
> 								   (type) __t
> 								   = (type);
> 								   if
> 								   (tree_code_type
> 								    [(int)
> 								     (((enum
> 									tree_code)
> 								       (__t)->
> 								       base.
> 								       code))]
> 								    !=
> 								    (tcc_type))
> 								   tree_class_check_failed
> 								   (__t,
> 								    __FUNCTION__);
> 								   __t;})->
> 								 base.
> 								 unsigned_flag))
>       dd = double_int_zext (dd, ((
> 				   {
> 				   __typeof (type) __t = (type);
> 				   if (tree_code_type
> 				       [(int)
> 					(((enum tree_code) (__t)->base.
> 					  code))] !=
> 				       (tcc_type))
> 				   tree_class_check_failed (__t,
> 							    __FUNCTION__);
> 				   __t;}
> 				 )->type.precision));
> }
> }
> /* The switch should be switch converted and later constant propagated.  */
> /* { dg-final { scan-tree-dump-not "tree_code_type.6" "optimized"} } */
> /* { dg-final { cleanup-tree-dump "optimized" } } */
> 
> 	* gimple-fold.c (maybe_fold_reference): Use fold_const_aggregate_ref.
> 	* tree-ssa-ccp.c (fold_const_aggregate_ref): Use
> 	fold_read_from_constant_string.
> Index: gimple-fold.c
> ===================================================================
> --- gimple-fold.c	(revision 163859)
> +++ gimple-fold.c	(working copy)
> @@ -462,14 +474,11 @@ static tree
>  maybe_fold_reference (tree expr, bool is_lhs)
>  {
>    tree *t = &expr;
> +  tree result;
>  
> -  if (TREE_CODE (expr) == ARRAY_REF
> -      && !is_lhs)
> -    {
> -      tree tem = fold_read_from_constant_string (expr);
> -      if (tem)
> -	return tem;
> -    }
> +  if (!is_lhs
> +      && (result = fold_const_aggregate_ref (expr)))
> +    return result;
>  
>    /* ???  We might want to open-code the relevant remaining cases
>       to avoid using the generic fold.  */
> Index: tree-ssa-ccp.c
> ===================================================================
> --- tree-ssa-ccp.c	(revision 163859)
> +++ tree-ssa-ccp.c	(working copy)
> @@ -1325,6 +1325,10 @@ fold_const_aggregate_ref (tree t)
>    if (TREE_CODE_CLASS (TREE_CODE (t)) == tcc_declaration)
>      return get_symbol_constant_value (t);
>  
> +  tem = fold_read_from_constant_string (t);
> +  if (tem)
> +    return tem;
> +
>    switch (TREE_CODE (t))
>      {
>      case ARRAY_REF:
> 
> 

-- 
Richard Guenther <rguenther@suse.de>
Novell / SUSE Labs
SUSE LINUX Products GmbH - Nuernberg - AG Nuernberg - HRB 16746 - GF: Markus Rex