8161147: jvm crashes when -XX:+UseCountedLoopSafepoints is enabled
Summary: don't convert loop with safepoint on the backedge to Counted loop
Reviewed-by: kvn
--- a/hotspot/src/share/vm/opto/loopnode.cpp Thu Jun 23 17:58:59 2016 +0000
+++ b/hotspot/src/share/vm/opto/loopnode.cpp Mon Jul 25 14:31:42 2016 -0700
@@ -279,8 +279,16 @@
return false;
// Allow funny placement of Safepoint
- if (back_control->Opcode() == Op_SafePoint)
+ if (back_control->Opcode() == Op_SafePoint) {
+ if (UseCountedLoopSafepoints) {
+ // Leaving the safepoint on the backedge and creating a
+ // CountedLoop will confuse optimizations. We can't move the
+ // safepoint around because its jvm state wouldn't match a new
+ // location. Give up on that loop.
+ return false;
+ }
back_control = back_control->in(TypeFunc::Control);
+ }
// Controlling test for loop
Node *iftrue = back_control;
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/compiler/loopopts/TestCountedLoopSafepointBackedge.java Mon Jul 25 14:31:42 2016 -0700
@@ -0,0 +1,52 @@
+/*
+ * Copyright (c) 2016, Red Hat, Inc. 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 8161147
+ * @summary Safepoint on backedge breaks UseCountedLoopSafepoints
+ * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement -XX:+UseCountedLoopSafepoints TestCountedLoopSafepointBackedge
+ *
+ */
+
+public class TestCountedLoopSafepointBackedge {
+ static void test(int[] arr, int inc) {
+ int i = 0;
+ for (;;) {
+ for (int j = 0; j < 10; j++);
+ arr[i] = i;
+ i++;
+ if (i >= 100) {
+ break;
+ }
+ for (int j = 0; j < 10; j++);
+ }
+ }
+
+ static public void main(String[] args) {
+ int[] arr = new int[100];
+ for (int i = 0; i < 20000; i++) {
+ test(arr, 1);
+ }
+ }
+}