[PATCH][20/n] Remove GENERIC stmt combining from SCCVN

Richard Biener rguenther@suse.de
Mon Sep 14 08:52:00 GMT 2015


On Sat, 12 Sep 2015, Eric Botcazou wrote:

> > 	* fold-const.c (fold_binary_loc): Move simplifying of comparisons
> > 	against the highest or lowest possible integer ...
> > 	* match.pd: ... as patterns here.
> 
> This incorrectly dropped the calls to omit_one_operand_loc, resulting in the 
> failure of the attached Ada test: if the operand has side effects, you cannot 
> replace the entire comparison with just 'true' or 'false'.

Still trying to reproduce, but I suppose you hit

 /* Comparisons with the highest or lowest possible integer of
    the specified precision will have known values.  */
 (simplify
  (cmp (convert?@2 @0) INTEGER_CST@1)
  (if ((INTEGRAL_TYPE_P (TREE_TYPE (@1)) || POINTER_TYPE_P (TREE_TYPE 
(@1)))
       && tree_nop_conversion_p (TREE_TYPE (@2), TREE_TYPE (@0)))
   (with
    {
      tree arg1_type = TREE_TYPE (@1);
      unsigned int prec = TYPE_PRECISION (arg1_type);
      wide_int max = wi::max_value (arg1_type);
      wide_int signed_max = wi::max_value (prec, SIGNED);
      wide_int min = wi::min_value (arg1_type);
    }
    (switch
     (if (wi::eq_p (@1, max))
      (switch
       (if (cmp == GT_EXPR)
        { constant_boolean_node (false, type); })
       (if (cmp == GE_EXPR)
        (eq @2 @1))
       (if (cmp == LE_EXPR)
        { constant_boolean_node (true, type); })

this which should handle side-effects in @0 just fine:

/* #line 2019 "/space/rguenther/src/svn/trunk/gcc/match.pd" */
                      if (cmp == LE_EXPR)
                        {
                          if (dump_file && (dump_flags & TDF_DETAILS)) 
fprintf (dump_file, "Applying pattern match.pd:2020, %s:%d\n", __FILE__, 
__LINE__);
                          tree res;
                          res =  constant_boolean_node (true, type);
                          if (TREE_SIDE_EFFECTS (captures[0]))
                            res = build2_loc (loc, COMPOUND_EXPR, type, 
fold_ignored_result (captures[0]), res);
                          return res;

note that genmatch "inlines" omit_one_operand, so you only see
fold_ignored_result here.

So maybe the issue is with some other pattern or was latent
elsewehere.  I'll have a closer look once I manage to reproduce
the issue.

Richard.

> 
> 	* gnat.dg/overflow_sum3.adb: New test.
> 
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nuernberg)



More information about the Gcc-patches mailing list