Fix PR 23141 and 23142

[Diego Novillo <dnovillo at redhat dot com>]

I hate these bugs.  There were two problems wrapped into one.  As discussed 
in http://gcc.gnu.org/ml/gcc/2005-09/msg00098.html, the logic to prevent 
infinite iterations in vrp_visit_phi_node should only trigger when the 
previous result and the new one are both VR_RANGEs.

That fixes a couple of Ada regressions and at the same time fixes a minor 
pessimization.  In most cases we were getting a new ~[val, val] anti-range 
from vrp_meet that was being converted into VR_VARYING by this code.

However, this was also hiding a bug in vrp_meet in cases where we met a 
VR_RANGE with a VR_ANTI_RANGE.  If both ranges had equivalence sets, 
instead of doing the intersection of equivalence sets we were just copying 
one into the other.  This was mis-compiling the C++ front end such that we 
would get tons of syntax errors while compiling libstdc++.

Bootstrapped and tested x86, x86-64, ia64 and ppc64.

2005-10-15  Diego Novillo  <dnovillo@redhat.com>

	PR 23141
	PR 23142
	* tree-vrp.c (vrp_meet): Fix the intersection of equivalence
	sets VR0->EQUIV and VR1->EQUIV when meeting a range and an
	anti-range.
	(vrp_visit_phi_node): Only prevent infinite iterations when
	the previous result and the new result are both VR_RANGEs.

Index: tree-vrp.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/tree-vrp.c,v
retrieving revision 2.62
diff -d -u -p -r2.62 tree-vrp.c
--- tree-vrp.c	4 Oct 2005 03:02:18 -0000	2.62
+++ tree-vrp.c	15 Oct 2005 14:26:11 -0000
@@ -3497,8 +3497,11 @@ vrp_meet (value_range_t *vr0, value_rang
 	  && !symbolic_range_p (vr1)
 	  && !value_ranges_intersect_p (vr0, vr1))
 	{
+	  /* Copy most of VR1 into VR0.  Don't copy VR1's equivalence
+	     set.  We need to compute the intersection of the two
+	     equivalence sets.  */
 	  if (vr1->type == VR_ANTI_RANGE)
-	    copy_value_range (vr0, vr1);
+	    set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr0->equiv);
 
 	  /* The resulting set of equivalences is the intersection of
 	     the two sets.  */
@@ -3609,7 +3612,7 @@ vrp_visit_phi_node (tree phi)
   /* To prevent infinite iterations in the algorithm, derive ranges
      when the new value is slightly bigger or smaller than the
      previous one.  */
-  if (lhs_vr->type == VR_RANGE)
+  if (lhs_vr->type == VR_RANGE && vr_result.type == VR_RANGE)
     {
       if (!POINTER_TYPE_P (TREE_TYPE (lhs)))
 	{