116 lines
4.6 KiB
Diff
116 lines
4.6 KiB
Diff
# HG changeset patch
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# User thartmann
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# Date 1468206230 -3600
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# Mon Jul 11 04:03:50 2016 +0100
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# Node ID 7c89f7f3f2c57d64970cc2ae3a81d24765830118
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# Parent 4b40867e627dd9043bc67a4795caa9834ef69478
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8159244, PR3074: Partially initialized string object created by C2's string concat optimization may escape
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Summary: Emit release barrier after String creation to prevent partially initialized object from escaping.
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Reviewed-by: kvn
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diff -r 4b40867e627d -r 7c89f7f3f2c5 src/share/vm/opto/stringopts.cpp
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--- openjdk/hotspot/src/share/vm/opto/stringopts.cpp Fri Jun 17 11:31:24 2016 +0200
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+++ openjdk/hotspot/src/share/vm/opto/stringopts.cpp Mon Jul 11 04:03:50 2016 +0100
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@@ -1,5 +1,5 @@
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/*
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- * Copyright (c) 2009, 2013, Oracle and/or its affiliates. All rights reserved.
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+ * Copyright (c) 2009, 2016, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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@@ -1640,6 +1640,12 @@
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kit.store_String_length(kit.control(), result, length);
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}
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kit.store_String_value(kit.control(), result, char_array);
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+
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+ // The value field is final. Emit a barrier here to ensure that the effect
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+ // of the initialization is committed to memory before any code publishes
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+ // a reference to the newly constructed object (see Parse::do_exits()).
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+ assert(AllocateNode::Ideal_allocation(result, _gvn) != NULL, "should be newly allocated");
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+ kit.insert_mem_bar(Op_MemBarRelease, result);
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} else {
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result = C->top();
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}
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diff -r 4b40867e627d -r 7c89f7f3f2c5 test/compiler/stringopts/TestStringObjectInitialization.java
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000
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+++ openjdk/hotspot/test/compiler/stringopts/TestStringObjectInitialization.java Mon Jul 11 04:03:50 2016 +0100
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@@ -0,0 +1,78 @@
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+/*
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+ * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
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+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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+ *
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+ * This code is free software; you can redistribute it and/or modify it
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+ * under the terms of the GNU General Public License version 2 only, as
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+ * published by the Free Software Foundation.
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+ *
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+ * This code is distributed in the hope that it will be useful, but WITHOUT
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+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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+ * version 2 for more details (a copy is included in the LICENSE file that
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+ * accompanied this code).
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+ *
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+ * You should have received a copy of the GNU General Public License version
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+ * 2 along with this work; if not, write to the Free Software Foundation,
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+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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+ *
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+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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+ * or visit www.oracle.com if you need additional information or have any
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+ * questions.
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+ */
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+
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+
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+import java.util.Arrays;
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+
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+/*
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+ * @test
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+ * @bug 8159244
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+ * @requires vm.gc == "Parallel" | vm.gc == "null"
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+ * @summary Verifies that no partially initialized String object escapes from
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+ * C2's String concat optimization in a highly concurrent setting.
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+ * This test triggers the bug in about 1 out of 10 runs.
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+ * @compile -XDstringConcat=inline TestStringObjectInitialization.java
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+ * @run main/othervm/timeout=300 -XX:+IgnoreUnrecognizedVMOptions -XX:-UseCompressedOops -XX:-CompactStrings
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+ * -XX:-UseG1GC -XX:+UseParallelGC TestStringObjectInitialization
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+ */
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+public class TestStringObjectInitialization {
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+
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+ String myString;
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+
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+ public static void main(String[] args) throws Exception {
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+ TestStringObjectInitialization t = new TestStringObjectInitialization();
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+ // Create some threads that concurrently update 'myString'
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+ for (int i = 0; i < 100; ++i) {
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+ (new Thread(new Runner(t))).start();
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+ }
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+ Thread last = new Thread(new Runner(t));
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+ last.start();
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+ last.join();
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+ }
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+
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+ private void add(String message) {
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+ // String escapes to other threads here
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+ myString += message;
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+ }
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+
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+ public void run(String s, String[] sArray) {
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+ // Trigger C2's string concatenation optimization
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+ add(s + Arrays.toString(sArray) + " const ");
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+ }
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+}
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+
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+class Runner implements Runnable {
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+ private TestStringObjectInitialization test;
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+
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+ public Runner(TestStringObjectInitialization t) {
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+ test = t;
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+ }
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+
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+ public void run(){
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+ String[] array = {"a", "b", "c"};
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+ for (int i = 0; i < 10000; ++i) {
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+ test.run("a", array);
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+ }
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+ }
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+}
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+
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