[patch gimplify]: Make sure comparison using boolean-type after gimplification

[Richard Guenther]

On Thu, May 26, 2011 at 12:46 PM, Richard Guenther
<richard.guenther@gmail.com> wrote:
> On Thu, May 26, 2011 at 12:20 PM, Kai Tietz <ktietz@redhat.com> wrote:
>> Hello,
>>
>> this patch ensures that after gimplification also comparison expressions using FE's boolean_type_node.  As we need to deal here with C/C++'s (obj-c/c++ and java's), Ada's, and Fortran's specific boolean types, this patch alters some checks in tree-cfg for Ada's sake, and we need to deal in fold-const about type-conversion of comparisons special.
>> Additionally it takes care that in forwprop pass we don't do type hoising for boolean types.
>>
>> ChangeLog
>>
>> 2011-05-26  Kai Tietz
>>
>>          * gimplify.c (gimple_boolify): Boolify all comparison
>>          expressions.
>>          (gimplify_expr): Use 'useless_type_conversion_p' for comparing
>>          org_type with boolean_type_node for TRUTH-expressions and comparisons.
>>          * fold-const.c (fold_unary_loc): Handle comparison conversions with
>>          boolean-type special.
>>          * tree-cfg.c (verify_gimple_comparison): Adjust check for boolean
>>          or compatible types.
>>          (verify_gimple_assign_unary): Likewise.
>>          * tree-ssa-forwprop.c (forward_propagate_comparison): Handle
>>          boolean case special.
>>
>> Tested on x86_64-pc-linux-gnu (multilib) with regression test for all standard languages (C, C++, Obj-C, Fortran, Java) plus Obj-C++ and Ada. Ok for apply?
>
> It obviously isn't ok to apply before a patch has gone in that will resolve
> all of the FAILs you specify.  Comments on the patch:
>
> @@ -7281,9 +7284,28 @@ gimplify_expr (tree *expr_p, gimple_seq
>                 plain wrong if bitfields are involved.  */
>                {
>                  tree type = TREE_TYPE (TREE_OPERAND (*expr_p, 1));
> +                 tree org_type = TREE_TYPE (*expr_p);
> +
> +                 if (!useless_type_conversion_p (org_type, boolean_type_node))
> +                   {
> +                     TREE_TYPE (*expr_p) = boolean_type_node;
> +                     *expr_p = fold_convert_loc (saved_location, org_type, *expr_p);
> +                     ret = GS_OK;
> +                     goto dont_recalculate;
> +                   }
>
> The above should be only done for !AGGREGATE_TYPE_P.  Probably then
> the strange dont_recalcuate goto can go away as well.
>
>                  if (!AGGREGATE_TYPE_P (type))
> -                   goto expr_2;
> +                   {
> +                     enum gimplify_status r0, r1;
> +
> +                     r0 = gimplify_expr (&TREE_OPERAND (*expr_p, 0), pre_p,
> +                                         post_p, is_gimple_val, fb_rvalue);
> +                     r1 = gimplify_expr (&TREE_OPERAND (*expr_p, 1), pre_p,
> +                                         post_p, is_gimple_val, fb_rvalue);
> +
> +                     ret = MIN (r0, r1);
> +                   }
> +
>
> why change this?
>
> @@ -7641,6 +7641,12 @@ fold_unary_loc (location_t loc, enum tre
>        }
>       else if (COMPARISON_CLASS_P (arg0))
>        {
> +         /* Don't optimize type change, if op0 is of kind boolean_type_node.
> +            Otherwise this will lead to race-condition on gimplification
> +            trying to boolify comparison expression.  */
> +         if (TREE_TYPE (op0) == boolean_type_node)
> +           return NULL_TREE;
> +
>          if (TREE_CODE (type) == BOOLEAN_TYPE)
>            {
>              arg0 = copy_node (arg0);
>
> The code leading here looks quite strange to me ...
>
> tree
> fold_unary_loc (location_t loc, enum tree_code code, tree type, tree op0)
> {
> ...
>  if (TREE_CODE_CLASS (code) == tcc_unary)
>    {
> ...
>      else if (COMPARISON_CLASS_P (arg0))
>        {
>          if (TREE_CODE (type) == BOOLEAN_TYPE)
>            {
>              arg0 = copy_node (arg0);
>              TREE_TYPE (arg0) = type;
>              return arg0;
>            }
>          else if (TREE_CODE (type) != INTEGER_TYPE)
>            return fold_build3_loc (loc, COND_EXPR, type, arg0,
>                                fold_build1_loc (loc, code, type,
>                                             integer_one_node),
>                                fold_build1_loc (loc, code, type,
>                                             integer_zero_node));
>        }
>
> so, for any tcc_unary, like NEGATE_EXPR, with BOOLEAN_TYPE,
> return arg0 ... sure.  Same for the 2nd case.  ~ (a == b) isn't
> the same as a == b ? ~1 : ~0.  I _suppose_ those cases were
> ment for CONVERT_EXPR_CODE_P (code) instead of all of tcc_unary,
> in which case they should be dropped or moved below where we
> handle conversions explicitly.
>
> That said - does anyone remember anything about that above code?
> Trying to do some svn blame history tracking now ...

Oh, the patch continues...

@@ -3208,7 +3208,10 @@ verify_gimple_comparison (tree type, tre
        && (!POINTER_TYPE_P (op0_type)
 	   || !POINTER_TYPE_P (op1_type)
 	   || TYPE_MODE (op0_type) != TYPE_MODE (op1_type)))
-      || !INTEGRAL_TYPE_P (type))
+      || !(TREE_CODE (type) == BOOLEAN_TYPE
+      	   || (TREE_TYPE (type) && TREE_CODE (type) == INTEGER_TYPE
+      	       && TREE_CODE (TREE_TYPE (type)) == BOOLEAN_TYPE)
+	   || (INTEGRAL_TYPE_P (type) && TYPE_PRECISION (type) == 1)))
     {

why that strange TREE_TYPE (TREE_TYPE ())) thing again?  Drop
that.

@@ -3352,6 +3355,8 @@ verify_gimple_assign_unary (gimple stmt)
     case TRUTH_NOT_EXPR:
       /* We require two-valued operand types.  */
       if (!(TREE_CODE (rhs1_type) == BOOLEAN_TYPE
+      	    || (TREE_TYPE (rhs1_type) && TREE_CODE (rhs1_type) == INTEGER_TYPE
+      	        && TREE_CODE (TREE_TYPE (rhs1_type)) == BOOLEAN_TYPE)
 	    || (INTEGRAL_TYPE_P (rhs1_type)
 		&& TYPE_PRECISION (rhs1_type) == 1)))
         {

likewise.

Richard.