Store the SSA name range type in the tree structure

At the moment, an anti range ~[A,B] is stored as [B+1,A-1].  This makes
it harder to store the range in the natural precision of A and B, since
B+1 and A-1 might not be representable in that precision.

This patch instead stores the original minimum and maximum values and
uses a spare tree bit to represent the range type.  The version below
is for trunk; I've also tested a wide-int version.

Tested on x86_64-linux-gnu.  OK to install?

Thanks,
Richard


gcc/
	* tree-core.h (tree_base): Document use of static_flag for SSA_NAME.
	* tree.h (SSA_NAME_ANTI_RANGE_P, SSA_NAME_RANGE_TYPE): New macros.
	* tree-ssanames.h (set_range_info): Add range_type argument.
	(duplicate_ssa_name_range_info): Likewise.
	* tree-ssanames.c (set_range_info): Take the range type as argument
	and store it in SSA_NAME_ANTI_RANGE_P.
	(duplicate_ssa_name_range_info): Likewise.
	(get_range_info): Use SSA_NAME_ANTI_RANGE_P.
	(set_nonzero_bits): Update call to set_range_info.
	(duplicate_ssa_name_fn): Update call to duplicate_ssa_name_range_info.
	* tree-ssa-copy.c (fini_copy_prop): Likewise.
	* tree-vrp.c (remove_range_assertions): Update call to set_range_info.
	(vrp_finalize): Likewise, passing anti-ranges directly.

On Thu, Nov 28, 2013 at 12:26 PM, Richard Sandiford
<rdsandiford@googlemail.com> wrote:
> At the moment, an anti range ~[A,B] is stored as [B+1,A-1].  This makes
> it harder to store the range in the natural precision of A and B, since
> B+1 and A-1 might not be representable in that precision.
>
> This patch instead stores the original minimum and maximum values and
> uses a spare tree bit to represent the range type.  The version below
> is for trunk; I've also tested a wide-int version.
>
> Tested on x86_64-linux-gnu.  OK to install?

Ok.

Thanks,
Richard.

> Thanks,
> Richard
>
>
> gcc/
>         * tree-core.h (tree_base): Document use of static_flag for SSA_NAME.
>         * tree.h (SSA_NAME_ANTI_RANGE_P, SSA_NAME_RANGE_TYPE): New macros.
>         * tree-ssanames.h (set_range_info): Add range_type argument.
>         (duplicate_ssa_name_range_info): Likewise.
>         * tree-ssanames.c (set_range_info): Take the range type as argument
>         and store it in SSA_NAME_ANTI_RANGE_P.
>         (duplicate_ssa_name_range_info): Likewise.
>         (get_range_info): Use SSA_NAME_ANTI_RANGE_P.
>         (set_nonzero_bits): Update call to set_range_info.
>         (duplicate_ssa_name_fn): Update call to duplicate_ssa_name_range_info.
>         * tree-ssa-copy.c (fini_copy_prop): Likewise.
>         * tree-vrp.c (remove_range_assertions): Update call to set_range_info.
>         (vrp_finalize): Likewise, passing anti-ranges directly.
>
> Index: gcc/tree-core.h
> ===================================================================
> --- gcc/tree-core.h     2013-11-15 18:23:21.113488640 +0000
> +++ gcc/tree-core.h     2013-11-28 11:12:32.956977322 +0000
> @@ -822,6 +822,9 @@ struct GTY(()) tree_base {
>         TRANSACTION_EXPR_OUTER in
>            TRANSACTION_EXPR
>
> +       SSA_NAME_ANTI_RANGE_P in
> +          SSA_NAME
> +
>     public_flag:
>
>         TREE_OVERFLOW in
> Index: gcc/tree.h
> ===================================================================
> --- gcc/tree.h  2013-11-20 10:58:57.275831561 +0000
> +++ gcc/tree.h  2013-11-28 11:12:32.969977280 +0000
> @@ -1434,6 +1434,14 @@ #define SSA_NAME_IS_DEFAULT_DEF(NODE) \
>  #define SSA_NAME_PTR_INFO(N) \
>     SSA_NAME_CHECK (N)->ssa_name.info.ptr_info
>
> +/* True if SSA_NAME_RANGE_INFO describes an anti-range.  */
> +#define SSA_NAME_ANTI_RANGE_P(N) \
> +    SSA_NAME_CHECK (N)->base.static_flag
> +
> +/* The type of range described by SSA_NAME_RANGE_INFO.  */
> +#define SSA_NAME_RANGE_TYPE(N) \
> +    (SSA_NAME_ANTI_RANGE_P (N) ? VR_ANTI_RANGE : VR_RANGE)
> +
>  /* Value range info attributes for SSA_NAMEs of non pointer-type variables.  */
>  #define SSA_NAME_RANGE_INFO(N) \
>      SSA_NAME_CHECK (N)->ssa_name.info.range_info
> Index: gcc/tree-ssanames.h
> ===================================================================
> --- gcc/tree-ssanames.h 2013-11-15 18:23:22.050485010 +0000
> +++ gcc/tree-ssanames.h 2013-11-28 11:12:32.964977296 +0000
> @@ -70,7 +70,8 @@ #define ssa_name(i) ((*cfun->gimple_df->
>  enum value_range_type { VR_UNDEFINED, VR_RANGE, VR_ANTI_RANGE, VR_VARYING };
>
>  /* Sets the value range to SSA.  */
> -extern void set_range_info (tree, double_int, double_int);
> +extern void set_range_info (tree, enum value_range_type, double_int,
> +                           double_int);
>  /* Gets the value range from SSA.  */
>  extern enum value_range_type get_range_info (const_tree, double_int *,
>                                              double_int *);
> @@ -93,7 +94,8 @@ extern struct ptr_info_def *get_ptr_info
>  extern tree copy_ssa_name_fn (struct function *, tree, gimple);
>  extern void duplicate_ssa_name_ptr_info (tree, struct ptr_info_def *);
>  extern tree duplicate_ssa_name_fn (struct function *, tree, gimple);
> -extern void duplicate_ssa_name_range_info (tree, struct range_info_def *);
> +extern void duplicate_ssa_name_range_info (tree, enum value_range_type,
> +                                          struct range_info_def *);
>  extern void release_defs (gimple);
>  extern void replace_ssa_name_symbol (tree, tree);
>
> Index: gcc/tree-ssanames.c
> ===================================================================
> --- gcc/tree-ssanames.c 2013-11-20 10:59:18.330782865 +0000
> +++ gcc/tree-ssanames.c 2013-11-28 11:12:32.963977300 +0000
> @@ -178,12 +178,14 @@ make_ssa_name_fn (struct function *fn, t
>    return t;
>  }
>
> -/* Store range information MIN, and MAX to tree ssa_name NAME.  */
> +/* Store range information RANGE_TYPE, MIN, and MAX to tree ssa_name NAME.  */
>
>  void
> -set_range_info (tree name, double_int min, double_int max)
> +set_range_info (tree name, enum value_range_type range_type, double_int min,
> +               double_int max)
>  {
>    gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
> +  gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
>    range_info_def *ri = SSA_NAME_RANGE_INFO (name);
>
>    /* Allocate if not available.  */
> @@ -194,12 +196,16 @@ set_range_info (tree name, double_int mi
>        ri->nonzero_bits = double_int::mask (TYPE_PRECISION (TREE_TYPE (name)));
>      }
>
> +  /* Record the range type.  */
> +  if (SSA_NAME_RANGE_TYPE (name) != range_type)
> +    SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
> +
>    /* Set the values.  */
>    ri->min = min;
>    ri->max = max;
>
>    /* If it is a range, try to improve nonzero_bits from the min/max.  */
> -  if (min.cmp (max, TYPE_UNSIGNED (TREE_TYPE (name))) != 1)
> +  if (range_type == VR_RANGE)
>      {
>        int prec = TYPE_PRECISION (TREE_TYPE (name));
>        double_int xorv;
> @@ -225,7 +231,6 @@ set_range_info (tree name, double_int mi
>  enum value_range_type
>  get_range_info (const_tree name, double_int *min, double_int *max)
>  {
> -  enum value_range_type range_type;
>    gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
>    gcc_assert (min && max);
>    range_info_def *ri = SSA_NAME_RANGE_INFO (name);
> @@ -236,22 +241,9 @@ get_range_info (const_tree name, double_
>               > 2 * HOST_BITS_PER_WIDE_INT))
>      return VR_VARYING;
>
> -  /* If min > max, it is VR_ANTI_RANGE.  */
> -  if (ri->min.cmp (ri->max, TYPE_UNSIGNED (TREE_TYPE (name))) == 1)
> -    {
> -      /* VR_ANTI_RANGE ~[min, max] is encoded as [max + 1, min - 1].  */
> -      range_type = VR_ANTI_RANGE;
> -      *min = ri->max + double_int_one;
> -      *max = ri->min - double_int_one;
> -    }
> -  else
> -  {
> -    /* Otherwise (when min <= max), it is VR_RANGE.  */
> -    range_type = VR_RANGE;
> -    *min = ri->min;
> -    *max = ri->max;
> -  }
> -  return range_type;
> +  *min = ri->min;
> +  *max = ri->max;
> +  return SSA_NAME_RANGE_TYPE (name);
>  }
>
>  /* Change non-zero bits bitmask of NAME.  */
> @@ -261,7 +253,7 @@ set_nonzero_bits (tree name, double_int
>  {
>    gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
>    if (SSA_NAME_RANGE_INFO (name) == NULL)
> -    set_range_info (name,
> +    set_range_info (name, VR_RANGE,
>                     tree_to_double_int (TYPE_MIN_VALUE (TREE_TYPE (name))),
>                     tree_to_double_int (TYPE_MAX_VALUE (TREE_TYPE (name))));
>    range_info_def *ri = SSA_NAME_RANGE_INFO (name);
> @@ -490,15 +482,17 @@ duplicate_ssa_name_ptr_info (tree name,
>    SSA_NAME_PTR_INFO (name) = new_ptr_info;
>  }
>
> -/* Creates a duplicate of the range_info_def at RANGE_INFO for use by
> -   the SSA name NAME.  */
> +/* Creates a duplicate of the range_info_def at RANGE_INFO of type
> +   RANGE_TYPE for use by the SSA name NAME.  */
>  void
> -duplicate_ssa_name_range_info (tree name, struct range_info_def *range_info)
> +duplicate_ssa_name_range_info (tree name, enum value_range_type range_type,
> +                              struct range_info_def *range_info)
>  {
>    struct range_info_def *new_range_info;
>
>    gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
>    gcc_assert (!SSA_NAME_RANGE_INFO (name));
> +  gcc_assert (!SSA_NAME_ANTI_RANGE_P (name));
>
>    if (!range_info)
>      return;
> @@ -506,6 +500,8 @@ duplicate_ssa_name_range_info (tree name
>    new_range_info = ggc_alloc_range_info_def ();
>    *new_range_info = *range_info;
>
> +  gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
> +  SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
>    SSA_NAME_RANGE_INFO (name) = new_range_info;
>  }
>
> @@ -530,7 +526,8 @@ duplicate_ssa_name_fn (struct function *
>        struct range_info_def *old_range_info = SSA_NAME_RANGE_INFO (name);
>
>        if (old_range_info)
> -       duplicate_ssa_name_range_info (new_name, old_range_info);
> +       duplicate_ssa_name_range_info (new_name, SSA_NAME_RANGE_TYPE (name),
> +                                      old_range_info);
>      }
>
>    return new_name;
> Index: gcc/tree-ssa-copy.c
> ===================================================================
> --- gcc/tree-ssa-copy.c 2013-11-20 10:59:13.528790271 +0000
> +++ gcc/tree-ssa-copy.c 2013-11-28 11:12:32.961977306 +0000
> @@ -572,6 +572,7 @@ fini_copy_prop (void)
>                    && SSA_NAME_RANGE_INFO (var)
>                    && !SSA_NAME_RANGE_INFO (copy_of[i].value))
>             duplicate_ssa_name_range_info (copy_of[i].value,
> +                                          SSA_NAME_RANGE_TYPE (var),
>                                            SSA_NAME_RANGE_INFO (var));
>         }
>      }
> Index: gcc/tree-vrp.c
> ===================================================================
> --- gcc/tree-vrp.c      2013-11-20 10:58:52.760847630 +0000
> +++ gcc/tree-vrp.c      2013-11-28 11:12:32.967977287 +0000
> @@ -6583,7 +6583,8 @@ remove_range_assertions (void)
>                     && all_imm_uses_in_stmt_or_feed_cond (var, stmt,
>                                                           single_pred (bb)))
>                   {
> -                   set_range_info (var, SSA_NAME_RANGE_INFO (lhs)->min,
> +                   set_range_info (var, SSA_NAME_RANGE_TYPE (lhs),
> +                                   SSA_NAME_RANGE_INFO (lhs)->min,
>                                     SSA_NAME_RANGE_INFO (lhs)->max);
>                     maybe_set_nonzero_bits (bb, var);
>                   }
> @@ -9589,36 +9590,12 @@ vrp_finalize (void)
>         continue;
>
>         if ((TREE_CODE (vr_value[i]->min) == INTEGER_CST)
> -           && (TREE_CODE (vr_value[i]->max) == INTEGER_CST))
> -         {
> -           if (vr_value[i]->type == VR_RANGE)
> -             set_range_info (name,
> -                             tree_to_double_int (vr_value[i]->min),
> -                             tree_to_double_int (vr_value[i]->max));
> -           else if (vr_value[i]->type == VR_ANTI_RANGE)
> -             {
> -               /* VR_ANTI_RANGE ~[min, max] is encoded compactly as
> -                  [max + 1, min - 1] without additional attributes.
> -                  When min value > max value, we know that it is
> -                  VR_ANTI_RANGE; it is VR_RANGE otherwise.  */
> -
> -               /* ~[0,0] anti-range is represented as
> -                  range.  */
> -               if (TYPE_UNSIGNED (TREE_TYPE (name))
> -                   && integer_zerop (vr_value[i]->min)
> -                   && integer_zerop (vr_value[i]->max))
> -                 set_range_info (name,
> -                                 double_int_one,
> -                                 double_int::max_value
> -                                 (TYPE_PRECISION (TREE_TYPE (name)), true));
> -               else
> -                 set_range_info (name,
> -                                 tree_to_double_int (vr_value[i]->max)
> -                                 + double_int_one,
> -                                 tree_to_double_int (vr_value[i]->min)
> -                                 - double_int_one);
> -             }
> -         }
> +           && (TREE_CODE (vr_value[i]->max) == INTEGER_CST)
> +           && (vr_value[i]->type == VR_RANGE
> +               || vr_value[i]->type == VR_ANTI_RANGE))
> +         set_range_info (name, vr_value[i]->type,
> +                         tree_to_double_int (vr_value[i]->min),
> +                         tree_to_double_int (vr_value[i]->max));
>        }
>
>    /* Free allocated memory.  */