cfgcleanup.c (try_optimize_cfg): Make sure merge_blocks doesn't merge bb with itself.

	* cfgcleanup.c (try_optimize_cfg): Make sure merge_blocks doesn't
	merge bb with itself.

	* gcc.c-torture/compile/20020605-1.c: New test.

From-SVN: r54456

gcc/ChangeLog

+2002-06-10  Jakub Jelinek  <jakub@redhat.com>
+
+	* cfgcleanup.c (try_optimize_cfg): Make sure merge_blocks doesn't
+	merge bb with itself.
+
 2002-06-10  Richard Henderson  <rth@redhat.com>
 
 	* config/alpha/alpha.md (builtin_zap): Fix thinkos expanding mask.

gcc/cfgcleanup.c

@@ -1675,6 +1675,7 @@ try_optimize_cfg (mode)
 		     && !(s->flags & EDGE_COMPLEX)
 		     && (c = s->dest) != EXIT_BLOCK_PTR
 		     && c->pred->pred_next == NULL
+		     && b != c
 		     /* If the jump insn has side effects,
 			we can't kill the edge.  */
 		     && (GET_CODE (b->end) != JUMP_INSN

gcc/testsuite/ChangeLog

+2002-06-10  Jakub Jelinek  <jakub@redhat.com>
+
+	* gcc.c-torture/compile/20020605-1.c: New test.
+
 2002-06-07  Roger Sayle  <roger@eyesopen.com>
 
 	* gcc.dg/20020607-2.c: New test case.

gcc/testsuite/gcc.c-torture/compile/20020605-1.c

+/* This testcase caused on IA-32 -O2 endless loop in
+   merge_blocks when trying to merge a basic block
+   with itself.  */
+
+void f (void)
+{
+  char *c;
+  do
+    {
+      if (c)
+	break;
+    }
+  while (1);
+  if (!c)
+    while (1)
+      f ();
+}