2006-10-13 Richard Guenther <rguenther@suse.de>

	PR tree-optimization/29446
	* tree-vrp.c (fix_equivalence_set): Remove.
	(extract_range_from_assert): Do not call fix_equivalence_set.
	(debug_value_range): Print a newline.
	(compare_name_with_value): For equivalence sets with
	inconsistent value ranges conservatively bail out.
	(compare_names): Likewise.

	* gcc.dg/torture/pr29446.c: New testcase.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@117705 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 23 insertions, 91 deletions

diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c
index 4a30e4ee8a5..8e67e8a3d2b 100644
--- a/gcc/tree-vrp.c
+++ b/gcc/tree-vrp.c
@@ -724,86 +724,6 @@ ssa_name_nonzero_p (tree t)
 }
 
 
-/* When extracting ranges from X_i = ASSERT_EXPR <Y_j, pred>, we will
-   initially consider X_i and Y_j equivalent, so the equivalence set
-   of Y_j is added to the equivalence set of X_i.  However, it is
-   possible to have a chain of ASSERT_EXPRs whose predicates are
-   actually incompatible.  This is usually the result of nesting of
-   contradictory if-then-else statements.  For instance, in PR 24670:
-
-   	count_4 has range [-INF, 63]
-
-   	if (count_4 != 0)
-	  {
-	    count_19 = ASSERT_EXPR <count_4, count_4 != 0>
-	    if (count_19 > 63)
-	      {
-	        count_18 = ASSERT_EXPR <count_19, count_19 > 63>
-		if (count_18 <= 63)
-		  ...
-	      }
-	  }
-
-   Notice that 'if (count_19 > 63)' is trivially false and will be
-   folded out at the end.  However, during propagation, the flowgraph
-   is not cleaned up and so, VRP will evaluate predicates more
-   predicates than necessary, so it must support these
-   inconsistencies.  The problem here is that because of the chaining
-   of ASSERT_EXPRs, the equivalency set for count_18 includes count_4.
-   Since count_4 has an incompatible range, we ICE when evaluating the
-   ranges in the equivalency set.  So, we need to remove count_4 from
-   it.  */
-
-static void
-fix_equivalence_set (value_range_t *vr_p)
-{
-  bitmap_iterator bi;
-  unsigned i;
-  bitmap e = vr_p->equiv;
-  bitmap to_remove;
-
-  /* Only detect inconsistencies on numeric ranges.  */
-  if (vr_p->type == VR_VARYING
-      || vr_p->type == VR_UNDEFINED
-      || symbolic_range_p (vr_p))
-    return;
-
-  to_remove = BITMAP_ALLOC (NULL);
-  EXECUTE_IF_SET_IN_BITMAP (e, 0, i, bi)
-    {
-      value_range_t *equiv_vr = vr_value[i];
-
-      if (equiv_vr->type == VR_VARYING
-	  || equiv_vr->type == VR_UNDEFINED)
-	continue;
-
-      if (vr_p->type == VR_RANGE
-	  && equiv_vr->type == VR_RANGE)
-	{
-	  /* Two ranges have an empty intersection if their end points
-	     are outside of the other range.  */
-	  if (compare_values (equiv_vr->min, vr_p->max) == 1
-	      || compare_values (equiv_vr->max, vr_p->min) == -1)
-	    bitmap_set_bit (to_remove, i);
-	}
-      else if ((equiv_vr->type == VR_RANGE && vr_p->type == VR_ANTI_RANGE)
-	       || (equiv_vr->type == VR_ANTI_RANGE && vr_p->type == VR_RANGE))
-	{
-	  /* A range and an anti-range have an empty intersection if
-	     their end points are the same.  FIXME,
-	     value_ranges_intersect_p should handle this
-	     automatically.  */
-	  if (compare_values (equiv_vr->min, vr_p->min) == 0
-	      && compare_values (equiv_vr->max, vr_p->max) == 0)
-	    bitmap_set_bit (to_remove, i);
-	}
-    }
-
-  bitmap_and_compl_into (vr_p->equiv, to_remove);
-  BITMAP_FREE (to_remove);
-}
-
-
 /* Extract value range information from an ASSERT_EXPR EXPR and store
    it in *VR_P.  */
 
@@ -1056,7 +976,7 @@ extract_range_from_assert (value_range_t *vr_p, tree expr)
       || var_vr->type == VR_UNDEFINED
       || symbolic_range_p (vr_p)
       || symbolic_range_p (var_vr))
-    goto done;
+    return;
 
   if (var_vr->type == VR_RANGE && vr_p->type == VR_RANGE)
     {
@@ -1191,11 +1111,6 @@ extract_range_from_assert (value_range_t *vr_p, tree expr)
 	    }
 	}
     }
-
-  /* Remove names from the equivalence set that have ranges
-     incompatible with VR_P.  */
-done:
-  fix_equivalence_set (vr_p);
 }
 
 
@@ -2438,6 +2353,7 @@ void
 debug_value_range (value_range_t *vr)
 {
   dump_value_range (stderr, vr);
+  fprintf (stderr, "\n");
 }
 
 
@@ -3555,8 +3471,16 @@ compare_name_with_value (enum tree_code comp, tree var, tree val)
       t = compare_range_with_value (comp, &equiv_vr, val);
       if (t)
 	{
-	  /* All the ranges should compare the same against VAL.  */
-	  gcc_assert (retval == NULL || t == retval);
+	  /* If we get different answers from different members
+	     of the equivalence set this check must be in a dead
+	     code region.  Folding it to a trap representation
+	     would be correct here.  For now just return don't-know.  */
+	  if (retval != NULL
+	      && t != retval)
+	    {
+	      retval = NULL_TREE;
+	      break;
+	    }
 	  retval = t;
 	}
     }
@@ -3638,9 +3562,17 @@ compare_names (enum tree_code comp, tree n1, tree n2)
 	  t = compare_ranges (comp, &vr1, &vr2);
 	  if (t)
 	    {
-	      /* All the ranges in the equivalent sets should compare
-		 the same.  */
-	      gcc_assert (retval == NULL || t == retval);
+	      /* If we get different answers from different members
+		 of the equivalence set this check must be in a dead
+		 code region.  Folding it to a trap representation
+		 would be correct here.  For now just return don't-know.  */
+	      if (retval != NULL
+		  && t != retval)
+		{
+		  bitmap_clear_bit (e1, SSA_NAME_VERSION (n1));
+		  bitmap_clear_bit (e2, SSA_NAME_VERSION (n2));
+		  return NULL_TREE;
+		}
 	      retval = t;
 	    }
 	}