1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/test/compiler/gcbarriers/TestMembarDependencies.java Mon Oct 15 11:00:27 2018 +0200
1.3 @@ -0,0 +1,98 @@
1.4 +/*
1.5 + * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + */
1.26 +
1.27 +/*
1.28 + * @test TestMembarDependencies
1.29 + * @bug 8172850
1.30 + * @summary Tests correct scheduling of memory loads around MembarVolatile emitted by GC barriers.
1.31 + * @library /testlibrary
1.32 + * @run driver compiler.membars.TestMembarDependencies
1.33 + */
1.34 +
1.35 +package compiler.membars;
1.36 +
1.37 +import com.oracle.java.testlibrary.*;
1.38 +
1.39 +public class TestMembarDependencies {
1.40 + private static TestMembarDependencies f1;
1.41 + private static TestMembarDependencies f2;
1.42 +
1.43 + public static void main(String args[]) throws Throwable {
1.44 + if (args.length == 0) {
1.45 + // For debugging, add "-XX:+TraceOptoPipelining"
1.46 + OutputAnalyzer oa = ProcessTools.executeTestJvm("-XX:+IgnoreUnrecognizedVMOptions",
1.47 + "-XX:-TieredCompilation", "-XX:-BackgroundCompilation", "-XX:+PrintOpto",
1.48 + "-XX:CompileCommand=compileonly,compiler.membars.TestMembarDependencies::test*",
1.49 + "-XX:CompileCommand=dontinline,compiler.membars.TestMembarDependencies::test_m1",
1.50 + TestMembarDependencies.class.getName(), "run");
1.51 + // C2 should not crash or bail out from compilation
1.52 + oa.shouldHaveExitValue(0);
1.53 + oa.shouldNotMatch("Bailout: Recompile without subsuming loads");
1.54 + System.out.println(oa.getOutput());
1.55 + } else {
1.56 + f2 = new TestMembarDependencies();
1.57 + // Trigger compilation of test1 and test2
1.58 + for (int i = 0; i < 10_000; ++i) {
1.59 + f2.test1(f2);
1.60 + f2.test2(f2);
1.61 + }
1.62 + }
1.63 + }
1.64 +
1.65 + public void test_m1() { }
1.66 + public void test_m2() { }
1.67 +
1.68 + public void test1(TestMembarDependencies obj) {
1.69 + // Try/catch/finally is used to create a CFG block without a test + jmpCon
1.70 + // allowing GCM to schedule the testN_mem_reg0 instruction into that block.
1.71 + try {
1.72 + // Method call defines memory state that is then
1.73 + // used by subsequent instructions/blocks (see below).
1.74 + test_m1();
1.75 + } catch (Exception e) {
1.76 +
1.77 + } finally {
1.78 + // Oop write to field emits a GC post-barrier with a MembarVolatile
1.79 + // which has a wide memory effect (kills all memory). This creates an
1.80 + // anti-dependency on all surrounding memory loads.
1.81 + f1 = obj;
1.82 + }
1.83 + // The empty method m2 is inlined but the null check of f2 remains. It is encoded
1.84 + // as CmpN(LoadN(MEM), NULL) where MEM is the memory after the call to test_m1().
1.85 + // This is matched to testN_mem_reg0 on x86 which is scheduled before the barrier
1.86 + // in the try/catch block due to the anti-dependency on the MembarVolatile.
1.87 + // C2 crashes in the register allocator when trying to spill the flag register
1.88 + // to keep the result of the testN instruction live from the try/catch block
1.89 + // until it is here.
1.90 + f2.test_m2();
1.91 + }
1.92 +
1.93 + public void test2(TestMembarDependencies obj) {
1.94 + // Same as test1 but without try/catch/finally.
1.95 + // This causes C2 to bail out in block local scheduling because testN_mem_reg0 is
1.96 + // scheduled into a block that already contains another test + jmpCon instruction.
1.97 + test_m1();
1.98 + f1 = obj;
1.99 + f2.test_m2();
1.100 + }
1.101 +}
