[PATCH] Fix fold_cond_expr_with_comparison (PR middle-end/40747)

[Richard Guenther]

On Wed, Jul 15, 2009 at 11:33 AM, Jakub Jelinek<jakub@redhat.com> wrote:
> Hi!
>
> This is something Paolo Bonzini fixed already for > and >= to MAX
> optimization, but is needed for MIN as well.  Since Richard's
> http://gcc.gnu.org/ml/gcc-patches/2008-04/msg01303.html
> change operand_equal_p ignores signedness and precision for INTEGER_CSTs,
> so we need to make sure MIN_EXPR is done in the right type.
> For MAX_EXPR the patch just cleans up formatting.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk/4.4?

Ok.

Thanks,
Richard.

> 2009-07-14  Jakub Jelinek  <jakub@redhat.com>
>
>        PR middle-end/40747
>        * fold-const.c (fold_cond_expr_with_comparison): When folding
>        < and <= to MIN, make sure the MIN uses the same type as the
>        comparison's operands.
>
>        * gcc.c-torture/execute/pr40747.c: New test.
>
> --- gcc/fold-const.c.jj 2009-07-09 08:10:38.000000000 +0200
> +++ gcc/fold-const.c    2009-07-14 20:39:46.000000000 +0200
> @@ -5310,31 +5310,35 @@ fold_cond_expr_with_comparison (tree typ
>        return fold_build3 (COND_EXPR, type, arg0, arg1, arg2);
>
>       case LT_EXPR:
> -       /* If C1 is C2 + 1, this is min(A, C2).  */
> +       /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
> +          MIN_EXPR, to preserve the signedness of the comparison.  */
>        if (! operand_equal_p (arg2, TYPE_MAX_VALUE (type),
>                               OEP_ONLY_CONST)
>            && operand_equal_p (arg01,
>                                const_binop (PLUS_EXPR, arg2,
>                                             build_int_cst (type, 1), 0),
>                                OEP_ONLY_CONST))
> -         return pedantic_non_lvalue (fold_build2 (MIN_EXPR,
> -                                                  type,
> -                                                  fold_convert (type, arg1),
> -                                                  arg2));
> +         {
> +           tem = fold_build2 (MIN_EXPR, TREE_TYPE (arg00), arg00,
> +                              fold_convert (TREE_TYPE (arg00), arg2));
> +           return pedantic_non_lvalue (fold_convert (type, tem));
> +         }
>        break;
>
>       case LE_EXPR:
> -       /* If C1 is C2 - 1, this is min(A, C2).  */
> +       /* If C1 is C2 - 1, this is min(A, C2), with the same care
> +          as above.  */
>        if (! operand_equal_p (arg2, TYPE_MIN_VALUE (type),
>                               OEP_ONLY_CONST)
>            && operand_equal_p (arg01,
>                                const_binop (MINUS_EXPR, arg2,
>                                             build_int_cst (type, 1), 0),
>                                OEP_ONLY_CONST))
> -         return pedantic_non_lvalue (fold_build2 (MIN_EXPR,
> -                                                  type,
> -                                                  fold_convert (type, arg1),
> -                                                  arg2));
> +         {
> +           tem = fold_build2 (MIN_EXPR, TREE_TYPE (arg00), arg00,
> +                              fold_convert (TREE_TYPE (arg00), arg2));
> +           return pedantic_non_lvalue (fold_convert (type, tem));
> +         }
>        break;
>
>       case GT_EXPR:
> @@ -5346,11 +5350,11 @@ fold_cond_expr_with_comparison (tree typ
>                                const_binop (MINUS_EXPR, arg2,
>                                             build_int_cst (type, 1), 0),
>                                OEP_ONLY_CONST))
> -         return pedantic_non_lvalue (fold_convert (type,
> -                                     fold_build2 (MAX_EXPR, TREE_TYPE (arg00),
> -                                                  arg00,
> -                                                  fold_convert (TREE_TYPE (arg00),
> -                                                                arg2))));
> +         {
> +           tem = fold_build2 (MAX_EXPR, TREE_TYPE (arg00), arg00,
> +                              fold_convert (TREE_TYPE (arg00), arg2));
> +           return pedantic_non_lvalue (fold_convert (type, tem));
> +         }
>        break;
>
>       case GE_EXPR:
> @@ -5361,11 +5365,11 @@ fold_cond_expr_with_comparison (tree typ
>                                const_binop (PLUS_EXPR, arg2,
>                                             build_int_cst (type, 1), 0),
>                                OEP_ONLY_CONST))
> -         return pedantic_non_lvalue (fold_convert (type,
> -                                     fold_build2 (MAX_EXPR, TREE_TYPE (arg00),
> -                                                  arg00,
> -                                                  fold_convert (TREE_TYPE (arg00),
> -                                                                arg2))));
> +         {
> +           tem = fold_build2 (MAX_EXPR, TREE_TYPE (arg00), arg00,
> +                              fold_convert (TREE_TYPE (arg00), arg2));
> +           return pedantic_non_lvalue (fold_convert (type, tem));
> +         }
>        break;
>       case NE_EXPR:
>        break;
> --- gcc/testsuite/gcc.c-torture/execute/pr40747.c.jj    2009-07-14 20:49:14.000000000 +0200
> +++ gcc/testsuite/gcc.c-torture/execute/pr40747.c       2009-07-14 20:48:55.000000000 +0200
> @@ -0,0 +1,22 @@
> +/* PR middle-end/40747 */
> +
> +extern void abort (void);
> +
> +int
> +foo (int i)
> +{
> +  return (i < 4 && i >= 0) ? i : 4;
> +}
> +
> +int
> +main ()
> +{
> +  if (foo (-1) != 4) abort ();
> +  if (foo (0) != 0) abort ();
> +  if (foo (1) != 1) abort ();
> +  if (foo (2) != 2) abort ();
> +  if (foo (3) != 3) abort ();
> +  if (foo (4) != 4) abort ();
> +  if (foo (5) != 4) abort ();
> +  return 0;
> +}
>
>        Jakub
>