Fix PR tree-optimization/72810

Sometimes the case labels of a switch have a different type than the
switch operand, e.g. in the test case below, the case labels have type t
and the switch operand has type int. Because the verifier expects that
case labels of a switch each have the exact same type, it's important to
avoid changing their types when truncating their range.

Does this patch look OK to commit after bootstrap + regtesting?

gcc/ChangeLog:

	PR tree-optimization/72810
	* tree-vrp.c (simplify_switch_using_ranges): Avoid changing
	the types of the case labels when truncating.

gcc/testsuite/ChangeLog:

	PR tree-optimization/72810
	* tree-ssa/vrp110.c: New test.
---
 gcc/testsuite/gcc.dg/tree-ssa/vrp110.c | 24 +++++++++++++++++++
 gcc/tree-vrp.c                         | 43 +++++++++++++++++++---------------
 2 files changed, 48 insertions(+), 19 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/vrp110.c

On Fri, Aug 5, 2016 at 3:08 PM, Patrick Palka <patrick@parcs.ath.cx> wrote:
> Sometimes the case labels of a switch have a different type than the
> switch operand, e.g. in the test case below, the case labels have type t
> and the switch operand has type int. Because the verifier expects that
> case labels of a switch each have the exact same type, it's important to
> avoid changing their types when truncating their range.
>
> Does this patch look OK to commit after bootstrap + regtesting?

Ok, though the verifier should possibly be made more forgiving and
allow all types_compatible_p.

Richard.

> gcc/ChangeLog:
>
>         PR tree-optimization/72810
>         * tree-vrp.c (simplify_switch_using_ranges): Avoid changing
>         the types of the case labels when truncating.
>
> gcc/testsuite/ChangeLog:
>
>         PR tree-optimization/72810
>         * tree-ssa/vrp110.c: New test.
> ---
>  gcc/testsuite/gcc.dg/tree-ssa/vrp110.c | 24 +++++++++++++++++++
>  gcc/tree-vrp.c                         | 43 +++++++++++++++++++---------------
>  2 files changed, 48 insertions(+), 19 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.dg/tree-ssa/vrp110.c
>
> diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp110.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp110.c
> new file mode 100644
> index 0000000..34d7eb4
> --- /dev/null
> +++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp110.c
> @@ -0,0 +1,24 @@
> +/* { dg-options "-O2" }  */
> +
> +extern void foo (void);
> +extern void bar (void);
> +
> +void
> +test (int i)
> +{
> +  if (i == 1)
> +    return;
> +
> +  typedef int t;
> +  t j = i;
> +  switch (j)
> +    {
> +    case 1:
> +    case 2:
> +      foo ();
> +      break;
> +    case 7:
> +      bar ();
> +      break;
> +    }
> +}
> diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
> index 7e3b513..2c166db 100644
> --- a/gcc/tree-vrp.c
> +++ b/gcc/tree-vrp.c
> @@ -9643,61 +9643,66 @@ simplify_switch_using_ranges (gswitch *stmt)
>        tree min_label = gimple_switch_label (stmt, min_idx);
>        tree max_label = gimple_switch_label (stmt, max_idx);
>
> +      /* Avoid changing the types of the case labels when truncating.  */
> +      tree case_label_type = TREE_TYPE (CASE_LOW (min_label));
> +      tree vr_min = fold_convert (case_label_type, vr->min);
> +      tree vr_max = fold_convert (case_label_type, vr->max);
> +
>        if (vr->type == VR_RANGE)
>         {
>           /* If OP's value range is [2,8] and the low label range is
>              0 ... 3, truncate the label's range to 2 .. 3.  */
> -         if (tree_int_cst_compare (CASE_LOW (min_label), vr->min) < 0
> +         if (tree_int_cst_compare (CASE_LOW (min_label), vr_min) < 0
>               && CASE_HIGH (min_label) != NULL_TREE
> -             && tree_int_cst_compare (CASE_HIGH (min_label), vr->min) >= 0)
> -           CASE_LOW (min_label) = vr->min;
> +             && tree_int_cst_compare (CASE_HIGH (min_label), vr_min) >= 0)
> +           CASE_LOW (min_label) = vr_min;
>
>           /* If OP's value range is [2,8] and the high label range is
>              7 ... 10, truncate the label's range to 7 .. 8.  */
> -         if (tree_int_cst_compare (CASE_LOW (max_label), vr->max) <= 0
> +         if (tree_int_cst_compare (CASE_LOW (max_label), vr_max) <= 0
>               && CASE_HIGH (max_label) != NULL_TREE
> -             && tree_int_cst_compare (CASE_HIGH (max_label), vr->max) > 0)
> -           CASE_HIGH (max_label) = vr->max;
> +             && tree_int_cst_compare (CASE_HIGH (max_label), vr_max) > 0)
> +           CASE_HIGH (max_label) = vr_max;
>         }
>        else if (vr->type == VR_ANTI_RANGE)
>         {
> -         tree one_cst = build_one_cst (TREE_TYPE (op));
> +         tree one_cst = build_one_cst (case_label_type);
>
>           if (min_label == max_label)
>             {
>               /* If OP's value range is ~[7,8] and the label's range is
>                  7 ... 10, truncate the label's range to 9 ... 10.  */
> -             if (tree_int_cst_compare (CASE_LOW (min_label), vr->min) == 0
> +             if (tree_int_cst_compare (CASE_LOW (min_label), vr_min) == 0
>                   && CASE_HIGH (min_label) != NULL_TREE
> -                 && tree_int_cst_compare (CASE_HIGH (min_label), vr->max) > 0)
> +                 && tree_int_cst_compare (CASE_HIGH (min_label), vr_max) > 0)
>                 CASE_LOW (min_label)
> -                 = int_const_binop (PLUS_EXPR, vr->max, one_cst);
> +                 = int_const_binop (PLUS_EXPR, vr_max, one_cst);
>
>               /* If OP's value range is ~[7,8] and the label's range is
>                  5 ... 8, truncate the label's range to 5 ... 6.  */
> -             if (tree_int_cst_compare (CASE_LOW (min_label), vr->min) < 0
> +             if (tree_int_cst_compare (CASE_LOW (min_label), vr_min) < 0
>                   && CASE_HIGH (min_label) != NULL_TREE
> -                 && tree_int_cst_compare (CASE_HIGH (min_label), vr->max) == 0)
> +                 && tree_int_cst_compare (CASE_HIGH (min_label), vr_max) == 0)
>                 CASE_HIGH (min_label)
> -                 = int_const_binop (MINUS_EXPR, vr->min, one_cst);
> +                 = int_const_binop (MINUS_EXPR, vr_min, one_cst);
>             }
>           else
>             {
>               /* If OP's value range is ~[2,8] and the low label range is
>                  0 ... 3, truncate the label's range to 0 ... 1.  */
> -             if (tree_int_cst_compare (CASE_LOW (min_label), vr->min) < 0
> +             if (tree_int_cst_compare (CASE_LOW (min_label), vr_min) < 0
>                   && CASE_HIGH (min_label) != NULL_TREE
> -                 && tree_int_cst_compare (CASE_HIGH (min_label), vr->min) >= 0)
> +                 && tree_int_cst_compare (CASE_HIGH (min_label), vr_min) >= 0)
>                 CASE_HIGH (min_label)
> -                 = int_const_binop (MINUS_EXPR, vr->min, one_cst);
> +                 = int_const_binop (MINUS_EXPR, vr_min, one_cst);
>
>               /* If OP's value range is ~[2,8] and the high label range is
>                  7 ... 10, truncate the label's range to 9 ... 10.  */
> -             if (tree_int_cst_compare (CASE_LOW (max_label), vr->max) <= 0
> +             if (tree_int_cst_compare (CASE_LOW (max_label), vr_max) <= 0
>                   && CASE_HIGH (max_label) != NULL_TREE
> -                 && tree_int_cst_compare (CASE_HIGH (max_label), vr->max) > 0)
> +                 && tree_int_cst_compare (CASE_HIGH (max_label), vr_max) > 0)
>                 CASE_LOW (max_label)
> -                 = int_const_binop (PLUS_EXPR, vr->max, one_cst);
> +                 = int_const_binop (PLUS_EXPR, vr_max, one_cst);
>             }
>         }
>
> --
> 2.9.2.614.g990027a
>