7125879: assert(proj != NULL) failed: must be found

Summary: Leave i_o attached to slow allocation call when there are no i_o users after the call.
Reviewed-by: iveresov, twisti

src/share/vm/opto/macro.cpp

@@ -1503,9 +1503,16 @@ void PhaseMacroExpand::expand_allocate_common(
   // if we generated only a slow call, we are done
   if (always_slow) {
     // Now we can unhook i_o.
+    if (result_phi_i_o->outcnt() > 1) {
       call->set_req(TypeFunc::I_O, top());
-    if (result_phi_i_o->outcnt() == 0)
-      _igvn.remove_dead_node(result_phi_i_o);
+    } else {
+      assert(result_phi_i_o->unique_ctrl_out() == call, "");
+      // Case of new array with negative size known during compilation.
+      // AllocateArrayNode::Ideal() optimization disconnect unreachable
+      // following code since call to runtime will throw exception.
+      // As result there will be no users of i_o after the call.
+      // Leave i_o attached to this call to avoid problems in preceding graph.
+    }
     return;
   }
 

test/compiler/7125879/Test7125879.java

+/*
+ * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 7125879
+ * @summary assert(proj != NULL) failed: must be found
+ *
+ * @run main/othervm -Xcomp Test7125879
+ */
+
+public class Test7125879 {
+    String var_1 = "abc";
+
+    public Test7125879() {
+        var_1 = var_1.replaceAll("d", "e") + var_1;
+    }
+
+    public static void main(String[] args) {
+        Test7125879 t = new Test7125879();
+        try {
+            t.test();
+        } catch(Throwable e) { }
+    }
+
+    private void test() {
+        new Test7125879().var_1 = ((Test7125879)(new Object[-1])[0]).var_1;
+    }
+}
+