diff -r 992120803410 -r e044997c2eda test/compiler/gcbarriers/TestMembarDependencies.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/compiler/gcbarriers/TestMembarDependencies.java	Mon Oct 15 11:00:27 2018 +0200
@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2017, 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 TestMembarDependencies
+ * @bug 8172850
+ * @summary Tests correct scheduling of memory loads around MembarVolatile emitted by GC barriers.
+ * @library /testlibrary
+ * @run driver compiler.membars.TestMembarDependencies
+ */
+
+package compiler.membars;
+
+import com.oracle.java.testlibrary.*;
+
+public class TestMembarDependencies {
+    private static TestMembarDependencies f1;
+    private static TestMembarDependencies f2;
+
+    public static void main(String args[]) throws Throwable {
+        if (args.length == 0) {
+            // For debugging, add "-XX:+TraceOptoPipelining"
+            OutputAnalyzer oa = ProcessTools.executeTestJvm("-XX:+IgnoreUnrecognizedVMOptions",
+                "-XX:-TieredCompilation", "-XX:-BackgroundCompilation", "-XX:+PrintOpto",
+                "-XX:CompileCommand=compileonly,compiler.membars.TestMembarDependencies::test*",
+                "-XX:CompileCommand=dontinline,compiler.membars.TestMembarDependencies::test_m1",
+                TestMembarDependencies.class.getName(), "run");
+            // C2 should not crash or bail out from compilation
+            oa.shouldHaveExitValue(0);
+            oa.shouldNotMatch("Bailout: Recompile without subsuming loads");
+            System.out.println(oa.getOutput());
+        } else {
+            f2 = new TestMembarDependencies();
+            // Trigger compilation of test1 and test2
+            for (int i = 0; i < 10_000; ++i) {
+              f2.test1(f2);
+              f2.test2(f2);
+            }
+        }
+    }
+
+    public void test_m1() { }
+    public void test_m2() { }
+
+    public void test1(TestMembarDependencies obj) {
+        // Try/catch/finally is used to create a CFG block without a test + jmpCon
+        // allowing GCM to schedule the testN_mem_reg0 instruction into that block.
+        try {
+            // Method call defines memory state that is then
+            // used by subsequent instructions/blocks (see below).
+            test_m1();
+        } catch (Exception e) {
+
+        } finally {
+            // Oop write to field emits a GC post-barrier with a MembarVolatile
+            // which has a wide memory effect (kills all memory). This creates an
+            // anti-dependency on all surrounding memory loads.
+            f1 = obj;
+        }
+        // The empty method m2 is inlined but the null check of f2 remains. It is encoded
+        // as CmpN(LoadN(MEM), NULL) where MEM is the memory after the call to test_m1().
+        // This is matched to testN_mem_reg0 on x86 which is scheduled before the barrier
+        // in the try/catch block due to the anti-dependency on the MembarVolatile.
+        // C2 crashes in the register allocator when trying to spill the flag register
+        // to keep the result of the testN instruction live from the try/catch block
+        // until it is here.
+        f2.test_m2();
+    }
+
+    public void test2(TestMembarDependencies obj) {
+        // Same as test1 but without try/catch/finally.
+        // This causes C2 to bail out in block local scheduling because testN_mem_reg0 is
+        // scheduled into a block that already contains another test + jmpCon instruction.
+        test_m1();
+        f1 = obj;
+        f2.test_m2();
+    }
+}