re PR tree-optimization/47677 (Hang in VRP)

2011-02-10  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/47677
	* tree-vrp.c (vrp_bitmap_equal_p): Fix comparison of empty bitmaps.

	* gcc.dg/torture/pr47677.c: New testcase.

From-SVN: r170002

gcc/ChangeLog

+2011-02-10  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/47677
+	* tree-vrp.c (vrp_bitmap_equal_p): Fix comparison of empty bitmaps.
+
 2011-02-10  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/47665

gcc/testsuite/ChangeLog

+2011-02-10  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/47677
+	* gcc.dg/torture/pr47677.c: New testcase.
+
 2011-02-10  Iain Sandoe  <iains@gcc.gnu.org>
 
 	* objc.dg/special/load-category-1.m: Remove unused header.

gcc/testsuite/gcc.dg/torture/pr47677.c

+/* { dg-do compile } */
+
+struct S { int s; int u; };
+extern int bar (void);
+extern struct S *baz (void);
+
+void
+foo (int x, struct S *y, char z, int *v, struct S *s)
+{
+  int c, d;
+  if (x & 2)
+    d = 1;
+  else
+    {
+      d = (x & 1) ? 11 : 0;
+      while ((c = (s->s != (s->u & 1) ? s->s : bar ())) != '\0');
+      c = (s->s != '\\' && (s->u & 4) ? s->s : bar ());
+      if (c == '<')
+        goto lab;
+    }
+  while ((c = ((s->u & 1) ? s->s : bar ())) != 0
+         && ((d != 11 && d != 17) || (v[c] & 1) == 0))
+    {
+    lab:;
+      switch (d)
+        {
+        case 14:
+          if (c == '}')
+            y = baz ();
+          d = y->s = z == '<' ? 17 : 11;
+        }
+    }
+}
+

gcc/tree-vrp.c

@@ -714,6 +714,8 @@ static inline bool
 vrp_bitmap_equal_p (const_bitmap b1, const_bitmap b2)
 {
   return (b1 == b2
+	  || ((!b1 || bitmap_empty_p (b1))
+	      && (!b2 || bitmap_empty_p (b2)))
 	  || (b1 && b2
 	      && bitmap_equal_p (b1, b2)));
 }