[PATCH] Fix PR83158

[PATCH] Fix PR83158

[Richard Biener]

Recent changes caused VRP to create [-2147483646, +INF] from
merging ~[0, 0] and [-2147483646, +INF].  This causes i386 specific
folding of lznct to no longer trigger.  The following extends the
existing special-casing of ~[0, 0] from pointer-like types to
pointer types and integer types > int (covering integral arguments).

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.

Richard.

2017-11-28  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/83158
	* tree-vrp.c (intersect_ranges): Prefer ~[0, 0] in a few more
	cases.

Index: gcc/tree-vrp.c
===================================================================
--- gcc/tree-vrp.c	(revision 255173)
+++ gcc/tree-vrp.c	(working copy)
@@ -6021,11 +6021,14 @@ intersect_ranges (enum value_range_type
 		   && vrp_val_is_max (vr1max))
 	    ;
 	  /* Choose the anti-range if it is ~[0,0], that range is special
-	     enough to special case when vr1's range is relatively wide.  */
+	     enough to special case when vr1's range is relatively wide.
+	     At least for types bigger than int - this covers pointers
+	     and arguments to functions like ctz.  */
 	  else if (*vr0min == *vr0max
 		   && integer_zerop (*vr0min)
-		   && (TYPE_PRECISION (TREE_TYPE (*vr0min))
-		       == TYPE_PRECISION (ptr_type_node))
+		   && ((TYPE_PRECISION (TREE_TYPE (*vr0min))
+			>= TYPE_PRECISION (integer_type_node))
+		       || POINTER_TYPE_P (TREE_TYPE (*vr0min)))
 		   && TREE_CODE (vr1max) == INTEGER_CST
 		   && TREE_CODE (vr1min) == INTEGER_CST
 		   && (wi::clz (wi::to_wide (vr1max) - wi::to_wide (vr1min))