--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/graal/com.oracle.graal.compiler.test/src/com/oracle/graal/compiler/test/UnbalancedMonitorsTest.java	Fri Oct 02 10:03:15 2015 -0700
@@ -0,0 +1,312 @@
+/*
+ * Copyright (c) 2015, 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.
+ */
+package com.oracle.graal.compiler.test;
+
+import jdk.internal.jvmci.code.BailoutException;
+import jdk.internal.jvmci.meta.ResolvedJavaMethod;
+import jdk.internal.org.objectweb.asm.ClassWriter;
+import jdk.internal.org.objectweb.asm.Label;
+import jdk.internal.org.objectweb.asm.MethodVisitor;
+import jdk.internal.org.objectweb.asm.Opcodes;
+
+import org.junit.Test;
+
+import com.oracle.graal.graphbuilderconf.GraphBuilderConfiguration;
+import com.oracle.graal.graphbuilderconf.GraphBuilderConfiguration.Plugins;
+import com.oracle.graal.graphbuilderconf.InvocationPlugins;
+import com.oracle.graal.java.GraphBuilderPhase;
+import com.oracle.graal.nodes.StructuredGraph;
+import com.oracle.graal.nodes.StructuredGraph.AllowAssumptions;
+import com.oracle.graal.phases.OptimisticOptimizations;
+
+/**
+ * Exercise handling of unbalanced monitor operations by the parser. Algorithmically Graal assumes
+ * that locks are statically block structured but that isn't something enforced by the bytecodes. In
+ * HotSpot a dataflow is performed to ensure they are properly structured and methods with
+ * unstructured locking aren't compiled and fall back to the interpreter. Having the Graal parser
+ * handle this directly is simplifying for targets of Graal since they don't have to provide a data
+ * flow that checks this property.
+ */
+public class UnbalancedMonitorsTest extends GraalCompilerTest implements Opcodes {
+    private static final String NAME = "com.oracle.graal.compiler.test.UnbalancedMonitorsTest$UnbalancedMonitors";
+    private static AsmLoader LOADER = new AsmLoader(UnbalancedMonitorsTest.class.getClassLoader());
+
+    @Test
+    public void runWrongOrder() throws Exception {
+        checkForBailout("wrongOrder");
+    }
+
+    @Test
+    public void runTooFewExits() throws Exception {
+        checkForBailout("tooFewExits");
+    }
+
+    @Test
+    public void runTooManyExits() throws Exception {
+        checkForBailout("tooManyExits");
+    }
+
+    @Test
+    public void runTooFewExitsExceptional() throws Exception {
+        checkForBailout("tooFewExitsExceptional");
+    }
+
+    @Test
+    public void runTooManyExitsExceptional() throws Exception {
+        checkForBailout("tooManyExitsExceptional");
+    }
+
+    private void checkForBailout(String name) throws ClassNotFoundException {
+        ResolvedJavaMethod method = getResolvedJavaMethod(LOADER.findClass(NAME), name);
+        try {
+            StructuredGraph graph = new StructuredGraph(method, AllowAssumptions.NO);
+            GraphBuilderConfiguration graphBuilderConfig = GraphBuilderConfiguration.getEagerDefault(new Plugins(new InvocationPlugins(getMetaAccess())));
+            graphBuilderConfig = graphBuilderConfig.withOmitAllExceptionEdges(false);
+            OptimisticOptimizations optimisticOpts = OptimisticOptimizations.NONE;
+
+            GraphBuilderPhase.Instance graphBuilder = new GraphBuilderPhase.Instance(getMetaAccess(), getProviders().getStampProvider(), null, graphBuilderConfig, optimisticOpts, null);
+            graphBuilder.apply(graph);
+        } catch (BailoutException e) {
+            if (e.getMessage().contains("unbalanced monitors")) {
+                return;
+            }
+            throw e;
+        }
+        assertTrue("should have bailed out", false);
+    }
+
+    // @formatter:off
+    // Template class used with Bytecode Outline to generate ASM code
+    //    public static class UnbalancedMonitors {
+    //
+    //        public UnbalancedMonitors() {
+    //        }
+    //
+    //        public Object wrongOrder(Object a, Object b) {
+    //            synchronized (a) {
+    //                synchronized (b) {
+    //                    return b;
+    //                }
+    //            }
+    //        }
+    //
+    //        public Object tooFewExits(Object a, Object b) {
+    //            synchronized (a) {
+    //                synchronized (b) {
+    //                    return b;
+    //                }
+    //            }
+    //        }
+    //
+    //        public boolean tooFewExitsExceptional(Object a, Object b) {
+    //            synchronized (a) {
+    //                synchronized (b) {
+    //                    return b.equals(a);
+    //                }
+    //            }
+    //        }
+    //    }
+    // @formatter:on
+
+    public static byte[] generateClass() {
+
+        ClassWriter cw = new ClassWriter(0);
+
+        cw.visit(52, ACC_SUPER | ACC_PUBLIC, "com/oracle/graal/compiler/test/UnbalancedMonitorsTest$UnbalancedMonitors", null, "java/lang/Object", null);
+
+        cw.visitSource("UnbalancedMonitorsTest.java", null);
+
+        cw.visitInnerClass("com/oracle/graal/compiler/test/UnbalancedMonitorsTest$UnbalancedMonitors", "com/oracle/graal/compiler/test/UnbalancedMonitorsTest", "UnbalancedMonitors", ACC_STATIC);
+
+        visitConstructor(cw);
+        visitWrongOrder(cw);
+        visitBlockStructured(cw, true, false);
+        visitBlockStructured(cw, true, true);
+        visitBlockStructured(cw, false, false);
+        visitBlockStructured(cw, false, true);
+        cw.visitEnd();
+
+        return cw.toByteArray();
+    }
+
+    private static void visitBlockStructured(ClassWriter cw, boolean normalReturnError, boolean tooMany) {
+        String name = (tooMany ? "tooMany" : "tooFew") + "Exits" + (normalReturnError ? "" : "Exceptional");
+        // Generate too many or too few exits down the either the normal or exceptional return paths
+        int exceptionalExitCount = normalReturnError ? 1 : (tooMany ? 2 : 0);
+        int normalExitCount = normalReturnError ? (tooMany ? 2 : 0) : 1;
+        MethodVisitor mv;
+        mv = cw.visitMethod(ACC_PUBLIC, name, "(Ljava/lang/Object;Ljava/lang/Object;)Z", null, null);
+        mv.visitCode();
+        Label l0 = new Label();
+        Label l1 = new Label();
+        Label l2 = new Label();
+        mv.visitTryCatchBlock(l0, l1, l2, null);
+        Label l3 = new Label();
+        mv.visitTryCatchBlock(l2, l3, l2, null);
+        Label l4 = new Label();
+        Label l5 = new Label();
+        Label l6 = new Label();
+        mv.visitTryCatchBlock(l4, l5, l6, null);
+        Label l7 = new Label();
+        mv.visitTryCatchBlock(l2, l7, l6, null);
+        Label l8 = new Label();
+        mv.visitLabel(l8);
+        mv.visitVarInsn(ALOAD, 1);
+        mv.visitInsn(DUP);
+        mv.visitVarInsn(ASTORE, 3);
+        mv.visitInsn(MONITORENTER);
+        mv.visitLabel(l4);
+        mv.visitVarInsn(ALOAD, 2);
+        mv.visitInsn(DUP);
+        mv.visitVarInsn(ASTORE, 4);
+        mv.visitInsn(MONITORENTER);
+        mv.visitLabel(l0);
+        mv.visitVarInsn(ALOAD, 2);
+        mv.visitVarInsn(ALOAD, 1);
+        mv.visitMethodInsn(INVOKEVIRTUAL, "java/lang/Object", "equals", "(Ljava/lang/Object;)Z", false);
+        mv.visitVarInsn(ALOAD, 4);
+        mv.visitInsn(MONITOREXIT);
+        mv.visitLabel(l1);
+        for (int i = 0; i < normalExitCount; i++) {
+            mv.visitVarInsn(ALOAD, 3);
+            mv.visitInsn(MONITOREXIT);
+        }
+        mv.visitLabel(l5);
+        mv.visitInsn(IRETURN);
+        mv.visitLabel(l2);
+        mv.visitFrame(Opcodes.F_FULL, 5, new Object[]{"com/oracle/graal/compiler/test/UnbalancedMonitorsTest$UnbalancedMonitors", "java/lang/Object", "java/lang/Object", "java/lang/Object",
+                        "java/lang/Object"}, 1, new Object[]{"java/lang/Throwable"});
+        mv.visitVarInsn(ALOAD, 4);
+        mv.visitInsn(MONITOREXIT);
+        mv.visitLabel(l3);
+        mv.visitInsn(ATHROW);
+        mv.visitLabel(l6);
+        mv.visitFrame(Opcodes.F_FULL, 4, new Object[]{"com/oracle/graal/compiler/test/UnbalancedMonitorsTest$UnbalancedMonitors", "java/lang/Object", "java/lang/Object", "java/lang/Object"}, 1,
+                        new Object[]{"java/lang/Throwable"});
+        for (int i = 0; i < exceptionalExitCount; i++) {
+            mv.visitVarInsn(ALOAD, 3);
+            mv.visitInsn(MONITOREXIT);
+        }
+        mv.visitLabel(l7);
+        mv.visitInsn(ATHROW);
+        Label l9 = new Label();
+        mv.visitLabel(l9);
+        mv.visitMaxs(2, 5);
+        mv.visitEnd();
+    }
+
+    private static void visitWrongOrder(ClassWriter cw) {
+        MethodVisitor mv;
+        mv = cw.visitMethod(ACC_PUBLIC, "wrongOrder", "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;", null, null);
+        mv.visitCode();
+        Label l0 = new Label();
+        Label l1 = new Label();
+        Label l2 = new Label();
+        mv.visitTryCatchBlock(l0, l1, l2, null);
+        Label l3 = new Label();
+        mv.visitTryCatchBlock(l2, l3, l2, null);
+        Label l4 = new Label();
+        Label l5 = new Label();
+        Label l6 = new Label();
+        mv.visitTryCatchBlock(l4, l5, l6, null);
+        Label l7 = new Label();
+        mv.visitTryCatchBlock(l2, l7, l6, null);
+        Label l8 = new Label();
+        mv.visitLabel(l8);
+        mv.visitVarInsn(ALOAD, 1);
+        mv.visitInsn(DUP);
+        mv.visitVarInsn(ASTORE, 3);
+        mv.visitInsn(MONITORENTER);
+        mv.visitLabel(l4);
+        mv.visitVarInsn(ALOAD, 2);
+        mv.visitInsn(DUP);
+        mv.visitVarInsn(ASTORE, 4);
+        mv.visitInsn(MONITORENTER);
+        mv.visitLabel(l0);
+        mv.visitVarInsn(ALOAD, 2);
+        mv.visitVarInsn(ALOAD, 3);
+        mv.visitInsn(MONITOREXIT);
+        mv.visitLabel(l1);
+        // Swapped exit order with exit above
+        mv.visitVarInsn(ALOAD, 4);
+        mv.visitInsn(MONITOREXIT);
+        mv.visitLabel(l5);
+        mv.visitInsn(ARETURN);
+        mv.visitLabel(l2);
+        mv.visitFrame(Opcodes.F_FULL, 5, new Object[]{"com/oracle/graal/compiler/test/UnbalancedMonitorsTest$UnbalancedMonitors", "java/lang/Object", "java/lang/Object", "java/lang/Object",
+                        "java/lang/Object"}, 1, new Object[]{"java/lang/Throwable"});
+        mv.visitVarInsn(ALOAD, 4);
+        mv.visitInsn(MONITOREXIT);
+        mv.visitLabel(l3);
+        mv.visitInsn(ATHROW);
+        mv.visitLabel(l6);
+        mv.visitFrame(Opcodes.F_FULL, 4, new Object[]{"com/oracle/graal/compiler/test/UnbalancedMonitorsTest$UnbalancedMonitors", "java/lang/Object", "java/lang/Object", "java/lang/Object"}, 1,
+                        new Object[]{"java/lang/Throwable"});
+        mv.visitVarInsn(ALOAD, 3);
+        mv.visitInsn(MONITOREXIT);
+        mv.visitLabel(l7);
+        mv.visitInsn(ATHROW);
+        Label l9 = new Label();
+        mv.visitLabel(l9);
+        mv.visitMaxs(2, 5);
+        mv.visitEnd();
+    }
+
+    private static void visitConstructor(ClassWriter cw) {
+        MethodVisitor mv;
+        mv = cw.visitMethod(ACC_PUBLIC, "<init>", "()V", null, null);
+        mv.visitCode();
+        Label l0 = new Label();
+        mv.visitLabel(l0);
+        mv.visitVarInsn(ALOAD, 0);
+        mv.visitMethodInsn(INVOKESPECIAL, "java/lang/Object", "<init>", "()V", false);
+        Label l1 = new Label();
+        mv.visitLabel(l1);
+        mv.visitInsn(RETURN);
+        Label l2 = new Label();
+        mv.visitLabel(l2);
+        mv.visitMaxs(1, 1);
+        mv.visitEnd();
+    }
+
+    public static class AsmLoader extends ClassLoader {
+        Class<?> loaded;
+
+        public AsmLoader(ClassLoader parent) {
+            super(parent);
+        }
+
+        @Override
+        protected Class<?> findClass(String name) throws ClassNotFoundException {
+            if (name.equals(NAME)) {
+                if (loaded != null) {
+                    return loaded;
+                }
+                byte[] bytes = generateClass();
+                return (loaded = defineClass(name, bytes, 0, bytes.length));
+            } else {
+                return super.findClass(name);
+            }
+        }
+    }
+}

--- a/graal/com.oracle.graal.java/src/com/oracle/graal/java/BytecodeParser.java	Fri Oct 02 15:23:31 2015 +0200
+++ b/graal/com.oracle.graal.java/src/com/oracle/graal/java/BytecodeParser.java	Fri Oct 02 10:03:15 2015 -0700
@@ -1972,9 +1972,6 @@
         }
 
         synchronizedEpilogue(BytecodeFrame.AFTER_BCI, x, kind);
-        if (frameState.lockDepth(false) != 0) {
-            throw bailout("unbalanced monitors");
-        }
     }
 
     protected void genMonitorEnter(ValueNode x, int bci) {
@@ -1985,6 +1982,9 @@
     }
 
     protected void genMonitorExit(ValueNode x, ValueNode escapedReturnValue, int bci) {
+        if (frameState.lockDepth(false) == 0) {
+            throw bailout("unbalanced monitors: too many exits");
+        }
         MonitorIdNode monitorId = frameState.peekMonitorId();
         ValueNode lockedObject = frameState.popLock();
         if (GraphUtil.originalValue(lockedObject) != GraphUtil.originalValue(x)) {
@@ -2520,6 +2520,9 @@
             genMonitorExit(methodSynchronizedObject, currentReturnValue, bci);
             assert !frameState.rethrowException();
         }
+        if (frameState.lockDepth(false) != 0) {
+            throw bailout("unbalanced monitors: too few exits exiting frame");
+        }
     }
 
     private void createExceptionDispatch(ExceptionDispatchBlock block) {
@@ -2646,6 +2649,9 @@
 
             try {
                 processBytecode(bci, opcode);
+            } catch (BailoutException e) {
+                // Don't wrap bailouts as parser errors
+                throw e;
             } catch (Throwable e) {
                 throw asParserError(e);
             }