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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.

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.  */


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