No need to modify class bytes for Java 10 support (#740)

18 files changed, 46 insertions, 225 deletions

diff --git a/org.jacoco.core.test.validation.java5/src/org/jacoco/core/test/validation/java5/FinallyTest.java b/org.jacoco.core.test.validation.java5/src/org/jacoco/core/test/validation/java5/FinallyTest.java
index 82fb08cc..3987ecaa 100644
--- a/org.jacoco.core.test.validation.java5/src/org/jacoco/core/test/validation/java5/FinallyTest.java
+++ b/org.jacoco.core.test.validation.java5/src/org/jacoco/core/test/validation/java5/FinallyTest.java
@@ -21,7 +21,6 @@ import java.util.HashSet;
 import java.util.Map;
 import java.util.Set;
 
-import org.jacoco.core.internal.BytecodeVersion;
 import org.jacoco.core.test.TargetLoader;
 import org.jacoco.core.test.validation.Source.Line;
 import org.jacoco.core.test.validation.ValidationTestBase;
@@ -194,7 +193,6 @@ public class FinallyTest extends ValidationTestBase {
 		final Set<String> gotoTags = new HashSet<String>();
 
 		byte[] b = TargetLoader.getClassDataAsBytes(FinallyTarget.class);
-		b = BytecodeVersion.downgradeIfNeeded(BytecodeVersion.get(b), b);
 
 		final ClassNode classNode = new ClassNode();
 		new ClassReader(b).accept(classNode, 0);
diff --git a/org.jacoco.core.test.validation.java5/src/org/jacoco/core/test/validation/java5/FramesTest.java b/org.jacoco.core.test.validation.java5/src/org/jacoco/core/test/validation/java5/FramesTest.java
index 2d502c31..a8bd1bca 100644
--- a/org.jacoco.core.test.validation.java5/src/org/jacoco/core/test/validation/java5/FramesTest.java
+++ b/org.jacoco.core.test.validation.java5/src/org/jacoco/core/test/validation/java5/FramesTest.java
@@ -18,7 +18,6 @@ import java.io.PrintWriter;
 import java.io.StringWriter;
 
 import org.jacoco.core.instr.Instrumenter;
-import org.jacoco.core.internal.BytecodeVersion;
 import org.jacoco.core.internal.instr.InstrSupport;
 import org.jacoco.core.runtime.IRuntime;
 import org.jacoco.core.runtime.SystemPropertiesRuntime;
@@ -87,9 +86,6 @@ public class FramesTest {
 	}
 
 	private byte[] calculateFrames(byte[] source) {
-		source = BytecodeVersion.downgradeIfNeeded(BytecodeVersion.get(source),
-				source);
-
 		ClassReader rc = new ClassReader(source);
 		ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES);
 
diff --git a/org.jacoco.core.test.validation.java5/src/org/jacoco/core/test/validation/java5/StructuredLockingTest.java b/org.jacoco.core.test.validation.java5/src/org/jacoco/core/test/validation/java5/StructuredLockingTest.java
index 8243c4bc..1d197bf9 100644
--- a/org.jacoco.core.test.validation.java5/src/org/jacoco/core/test/validation/java5/StructuredLockingTest.java
+++ b/org.jacoco.core.test.validation.java5/src/org/jacoco/core/test/validation/java5/StructuredLockingTest.java
@@ -20,7 +20,6 @@ import java.util.List;
 import java.util.Set;
 
 import org.jacoco.core.instr.Instrumenter;
-import org.jacoco.core.internal.BytecodeVersion;
 import org.jacoco.core.runtime.IRuntime;
 import org.jacoco.core.runtime.SystemPropertiesRuntime;
 import org.jacoco.core.test.TargetLoader;
@@ -65,9 +64,6 @@ public class StructuredLockingTest {
 		Instrumenter instrumenter = new Instrumenter(runtime);
 		byte[] instrumented = instrumenter.instrument(source, "TestTarget");
 
-		final int version = BytecodeVersion.get(instrumented);
-		instrumented = BytecodeVersion.downgradeIfNeeded(version, instrumented);
-
 		ClassNode cn = new ClassNode();
 		new ClassReader(instrumented).accept(cn, 0);
 		for (MethodNode mn : cn.methods) {
diff --git a/org.jacoco.core.test/src/org/jacoco/core/analysis/AnalyzerTest.java b/org.jacoco.core.test/src/org/jacoco/core/analysis/AnalyzerTest.java
index d8828340..b52c6e32 100644
--- a/org.jacoco.core.test/src/org/jacoco/core/analysis/AnalyzerTest.java
+++ b/org.jacoco.core.test/src/org/jacoco/core/analysis/AnalyzerTest.java
@@ -11,6 +11,7 @@
  *******************************************************************************/
 package org.jacoco.core.analysis;
 
+import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNull;
@@ -36,7 +37,6 @@ import java.util.zip.ZipEntry;
 import java.util.zip.ZipOutputStream;
 
 import org.jacoco.core.data.ExecutionDataStore;
-import org.jacoco.core.internal.BytecodeVersion;
 import org.jacoco.core.internal.data.CRC64;
 import org.jacoco.core.test.TargetLoader;
 import org.junit.Before;
@@ -90,12 +90,16 @@ public class AnalyzerTest {
 	}
 
 	@Test
-	public void should_analyze_java10_class() throws Exception {
-		final byte[] bytes = createClass(BytecodeVersion.V10);
+	public void should_not_modify_class_bytes_to_support_next_version()
+			throws Exception {
+		final byte[] originalBytes = createClass(Opcodes.V12);
+		final byte[] bytes = new byte[originalBytes.length];
+		System.arraycopy(originalBytes, 0, bytes, 0, originalBytes.length);
 		final long expectedClassId = CRC64.classId(bytes);
 
 		analyzer.analyzeClass(bytes, "");
 
+		assertArrayEquals(originalBytes, bytes);
 		assertEquals(expectedClassId, classes.get("Foo").getId());
 	}
 
diff --git a/org.jacoco.core.test/src/org/jacoco/core/instr/ClassFileVersionsTest.java b/org.jacoco.core.test/src/org/jacoco/core/instr/ClassFileVersionsTest.java
index 38bd8083..338d85d3 100644
--- a/org.jacoco.core.test/src/org/jacoco/core/instr/ClassFileVersionsTest.java
+++ b/org.jacoco.core.test/src/org/jacoco/core/instr/ClassFileVersionsTest.java
@@ -22,6 +22,7 @@ import static org.objectweb.asm.Opcodes.INVOKESPECIAL;
 import static org.objectweb.asm.Opcodes.INVOKEVIRTUAL;
 import static org.objectweb.asm.Opcodes.POP;
 import static org.objectweb.asm.Opcodes.RETURN;
+import static org.objectweb.asm.Opcodes.V10;
 import static org.objectweb.asm.Opcodes.V11;
 import static org.objectweb.asm.Opcodes.V12;
 import static org.objectweb.asm.Opcodes.V1_1;
@@ -36,7 +37,6 @@ import static org.objectweb.asm.Opcodes.V9;
 
 import java.io.IOException;
 
-import org.jacoco.core.internal.BytecodeVersion;
 import org.jacoco.core.internal.instr.InstrSupport;
 import org.jacoco.core.runtime.IRuntime;
 import org.jacoco.core.runtime.SystemPropertiesRuntime;
@@ -100,7 +100,7 @@ public class ClassFileVersionsTest {
 
 	@Test
 	public void test_10() throws IOException {
-		testVersion(BytecodeVersion.V10, true);
+		testVersion(V10, true);
 	}
 
 	@Test
@@ -124,8 +124,6 @@ public class ClassFileVersionsTest {
 	}
 
 	private void assertFrames(byte[] source, final boolean expected) {
-		int version = BytecodeVersion.get(source);
-		source = BytecodeVersion.downgradeIfNeeded(version, source);
 		new ClassReader(source)
 				.accept(new ClassVisitor(InstrSupport.ASM_API_VERSION) {
 
diff --git a/org.jacoco.core.test/src/org/jacoco/core/instr/InstrumenterTest.java b/org.jacoco.core.test/src/org/jacoco/core/instr/InstrumenterTest.java
index 85882352..94828edf 100644
--- a/org.jacoco.core.test/src/org/jacoco/core/instr/InstrumenterTest.java
+++ b/org.jacoco.core.test/src/org/jacoco/core/instr/InstrumenterTest.java
@@ -35,7 +35,6 @@ import java.util.zip.ZipInputStream;
 import java.util.zip.ZipOutputStream;
 
 import org.jacoco.core.analysis.AnalyzerTest;
-import org.jacoco.core.internal.BytecodeVersion;
 import org.jacoco.core.internal.data.CRC64;
 import org.jacoco.core.internal.instr.InstrSupport;
 import org.jacoco.core.runtime.IExecutionDataAccessorGenerator;
@@ -97,17 +96,16 @@ public class InstrumenterTest {
 	}
 
 	@Test
-	public void should_instrument_java10_class() throws Exception {
-		final byte[] originalBytes = createClass(BytecodeVersion.V10);
+	public void should_not_modify_class_bytes_to_support_next_version()
+			throws Exception {
+		final byte[] originalBytes = createClass(Opcodes.V12);
 		final byte[] bytes = new byte[originalBytes.length];
 		System.arraycopy(originalBytes, 0, bytes, 0, originalBytes.length);
 		final long expectedClassId = CRC64.classId(bytes);
 
-		final byte[] instrumentedBytes = instrumenter.instrument(bytes, "");
+		instrumenter.instrument(bytes, "");
 
 		assertArrayEquals(originalBytes, bytes);
-		assertEquals(BytecodeVersion.V10,
-				BytecodeVersion.get(instrumentedBytes));
 		assertEquals(expectedClassId, accessorGenerator.classId);
 	}
 
diff --git a/org.jacoco.core.test/src/org/jacoco/core/instr/ResizeInstructionsTest.java b/org.jacoco.core.test/src/org/jacoco/core/instr/ResizeInstructionsTest.java
index fb639ca3..02016445 100644
--- a/org.jacoco.core.test/src/org/jacoco/core/instr/ResizeInstructionsTest.java
+++ b/org.jacoco.core.test/src/org/jacoco/core/instr/ResizeInstructionsTest.java
@@ -15,8 +15,6 @@ import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertSame;
 import static org.junit.Assert.assertTrue;
 
-import org.jacoco.core.instr.Instrumenter;
-import org.jacoco.core.internal.BytecodeVersion;
 import org.jacoco.core.internal.instr.InstrSupport;
 import org.jacoco.core.runtime.IRuntime;
 import org.jacoco.core.runtime.RuntimeData;
@@ -62,8 +60,6 @@ public class ResizeInstructionsTest {
 	@Test
 	public void should_not_loose_InnerClasses_attribute() throws Exception {
 		byte[] source = TargetLoader.getClassDataAsBytes(Inner.class);
-		final int version = BytecodeVersion.get(source);
-		source = BytecodeVersion.downgradeIfNeeded(version, source);
 
 		final ClassReader cr = new ClassReader(source);
 		final ClassWriter cw = new ClassWriter(0);
@@ -81,7 +77,6 @@ public class ResizeInstructionsTest {
 			}
 		}, 0);
 		source = cw.toByteArray();
-		BytecodeVersion.set(source, version);
 
 		final byte[] bytes = instrumenter.instrument(source, "");
 
diff --git a/org.jacoco.core.test/src/org/jacoco/core/internal/BytecodeVersionTest.java b/org.jacoco.core.test/src/org/jacoco/core/internal/BytecodeVersionTest.java
deleted file mode 100644
index 6bc4ca9e..00000000
--- a/org.jacoco.core.test/src/org/jacoco/core/internal/BytecodeVersionTest.java
+++ /dev/null
@@ -1,62 +0,0 @@
-/*******************************************************************************
- * Copyright (c) 2009, 2018 Mountainminds GmbH & Co. KG and Contributors
- * All rights reserved. This program and the accompanying materials
- * are made available under the terms of the Eclipse Public License v1.0
- * which accompanies this distribution, and is available at
- * http://www.eclipse.org/legal/epl-v10.html
- *
- * Contributors:
- *    Evgeny Mandrikov - initial API and implementation
- *
- *******************************************************************************/
-package org.jacoco.core.internal;
-
-import org.junit.Test;
-import org.objectweb.asm.ClassWriter;
-import org.objectweb.asm.Opcodes;
-
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotSame;
-import static org.junit.Assert.assertSame;
-
-public class BytecodeVersionTest {
-
-	@Test
-	public void should_get_and_set_major_version() {
-		final byte[] bytes = createClass(Opcodes.V1_1);
-		assertEquals(45, BytecodeVersion.get(bytes));
-
-		BytecodeVersion.set(bytes, Opcodes.V1_2);
-		assertEquals(46, BytecodeVersion.get(bytes));
-	}
-
-	@Test
-	public void should_return_original_when_not_java10() {
-		final byte[] originalBytes = createClass(Opcodes.V9);
-
-		final byte[] bytes = BytecodeVersion.downgradeIfNeeded(Opcodes.V9,
-				originalBytes);
-
-		assertSame(originalBytes, bytes);
-	}
-
-	@Test
-	public void should_return_copy_when_java10() {
-		final byte[] originalBytes = createClass(BytecodeVersion.V10);
-
-		final byte[] bytes = BytecodeVersion
-				.downgradeIfNeeded(BytecodeVersion.V10, originalBytes);
-
-		assertNotSame(originalBytes, bytes);
-		assertEquals(Opcodes.V9, BytecodeVersion.get(bytes));
-		assertEquals(BytecodeVersion.V10, BytecodeVersion.get(originalBytes));
-	}
-
-	private static byte[] createClass(final int version) {
-		final ClassWriter cw = new ClassWriter(0);
-		cw.visit(version, 0, "Foo", null, "java/lang/Object", null);
-		cw.visitEnd();
-		return cw.toByteArray();
-	}
-
-}
diff --git a/org.jacoco.core.test/src/org/jacoco/core/internal/data/CRC64Test.java b/org.jacoco.core.test/src/org/jacoco/core/internal/data/CRC64Test.java
index 39f7d508..ffb60801 100644
--- a/org.jacoco.core.test/src/org/jacoco/core/internal/data/CRC64Test.java
+++ b/org.jacoco.core.test/src/org/jacoco/core/internal/data/CRC64Test.java
@@ -16,7 +16,6 @@ import static org.junit.Assert.assertEquals;
 import java.io.UnsupportedEncodingException;
 
 import org.jacoco.core.data.ExecutionDataWriter;
-import org.jacoco.core.internal.BytecodeVersion;
 import org.junit.Test;
 import org.objectweb.asm.ClassWriter;
 import org.objectweb.asm.Opcodes;
@@ -29,7 +28,7 @@ public class CRC64Test {
 	@Test
 	public void except_java_9_checksums_should_be_different_for_different_bytecode_versions() {
 		assertEquals(0x589E9080A572741EL,
-				CRC64.classId(createClass(BytecodeVersion.V10)));
+				CRC64.classId(createClass(Opcodes.V10)));
 
 		// should remove workaround for Java 9
 		// during change of exec file version
diff --git a/org.jacoco.core.test/src/org/jacoco/core/internal/instr/InstrSupportTest.java b/org.jacoco.core.test/src/org/jacoco/core/internal/instr/InstrSupportTest.java
index c1b3044b..dda12bfd 100644
--- a/org.jacoco.core.test/src/org/jacoco/core/internal/instr/InstrSupportTest.java
+++ b/org.jacoco.core.test/src/org/jacoco/core/internal/instr/InstrSupportTest.java
@@ -15,7 +15,6 @@ import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
 
-import org.jacoco.core.internal.BytecodeVersion;
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
@@ -43,6 +42,13 @@ public class InstrSupportTest {
 	}
 
 	@Test
+	public void getVersionMajor_should_return_major_version_number() {
+		final byte[] bytes = new byte[] { (byte) 0xCA, (byte) 0xFE, (byte) 0xBA,
+				(byte) 0xBE, /* minor */ 0x00, 0x03, /* major */ 0x00, 0x2D };
+		assertEquals(45, InstrSupport.getVersionMajor(bytes));
+	}
+
+	@Test
 	public void needFrames_should_return_false_for_versions_less_than_1_6() {
 		assertFalse(InstrSupport.needsFrames(Opcodes.V1_1));
 		assertFalse(InstrSupport.needsFrames(Opcodes.V1_2));
@@ -57,7 +63,7 @@ public class InstrSupportTest {
 		assertTrue(InstrSupport.needsFrames(Opcodes.V1_7));
 		assertTrue(InstrSupport.needsFrames(Opcodes.V1_8));
 		assertTrue(InstrSupport.needsFrames(Opcodes.V9));
-		assertTrue(InstrSupport.needsFrames(BytecodeVersion.V10));
+		assertTrue(InstrSupport.needsFrames(Opcodes.V10));
 		assertTrue(InstrSupport.needsFrames(Opcodes.V11));
 		assertTrue(InstrSupport.needsFrames(Opcodes.V12));
 	}
diff --git a/org.jacoco.core.test/src/org/jacoco/core/runtime/ModifiedSystemClassRuntimeTest.java b/org.jacoco.core.test/src/org/jacoco/core/runtime/ModifiedSystemClassRuntimeTest.java
index 03a58018..8a968840 100644
--- a/org.jacoco.core.test/src/org/jacoco/core/runtime/ModifiedSystemClassRuntimeTest.java
+++ b/org.jacoco.core.test/src/org/jacoco/core/runtime/ModifiedSystemClassRuntimeTest.java
@@ -25,12 +25,8 @@ import java.lang.reflect.Method;
 import java.lang.reflect.Modifier;
 import java.lang.reflect.Proxy;
 
-import org.jacoco.core.internal.BytecodeVersion;
 import org.jacoco.core.test.TargetLoader;
 import org.junit.Test;
-import org.objectweb.asm.ClassReader;
-import org.objectweb.asm.ClassWriter;
-import org.objectweb.asm.tree.ClassNode;
 
 /**
  * Unit tests for {@link ModifiedSystemClassRuntime}.
@@ -49,28 +45,6 @@ public class ModifiedSystemClassRuntimeTest extends RuntimeTestBase {
 		ModifiedSystemClassRuntime.createFor(inst, TARGET_CLASS_NAME);
 	}
 
-	@Test
-	public void should_instrument_java10_class() {
-		final byte[] bytes = createClass(BytecodeVersion.V10);
-
-		byte[] instrumented = ModifiedSystemClassRuntime.instrument(bytes,
-				"accessField");
-
-		assertEquals(BytecodeVersion.V10, BytecodeVersion.get(instrumented));
-		instrumented = BytecodeVersion.downgradeIfNeeded(BytecodeVersion.V10,
-				instrumented);
-		final ClassNode classNode = new ClassNode();
-		new ClassReader(instrumented).accept(classNode, 0);
-		assertEquals("accessField", classNode.fields.get(0).name);
-	}
-
-	private static byte[] createClass(final int version) {
-		final ClassWriter cw = new ClassWriter(0);
-		cw.visit(version, 0, "Foo", null, "java/lang/Object", null);
-		cw.visitEnd();
-		return cw.toByteArray();
-	}
-
 	/** This static member emulate the instrumented system class. */
 	public static Object accessField;
 
diff --git a/org.jacoco.core/src/org/jacoco/core/analysis/Analyzer.java b/org.jacoco.core/src/org/jacoco/core/analysis/Analyzer.java
index 92d640d2..01ffd5d3 100644
--- a/org.jacoco.core/src/org/jacoco/core/analysis/Analyzer.java
+++ b/org.jacoco.core/src/org/jacoco/core/analysis/Analyzer.java
@@ -22,7 +22,6 @@ import java.util.zip.ZipInputStream;
 
 import org.jacoco.core.data.ExecutionData;
 import org.jacoco.core.data.ExecutionDataStore;
-import org.jacoco.core.internal.BytecodeVersion;
 import org.jacoco.core.internal.ContentTypeDetector;
 import org.jacoco.core.internal.InputStreams;
 import org.jacoco.core.internal.Pack200Streams;
@@ -113,9 +112,7 @@ public class Analyzer {
 
 	private void analyzeClass(final byte[] source) {
 		final long classId = CRC64.classId(source);
-		final int version = BytecodeVersion.get(source);
-		final byte[] b = BytecodeVersion.downgradeIfNeeded(version, source);
-		final ClassReader reader = new ClassReader(b);
+		final ClassReader reader = new ClassReader(source);
 		if ((reader.getAccess() & Opcodes.ACC_SYNTHETIC) != 0) {
 			return;
 		}
diff --git a/org.jacoco.core/src/org/jacoco/core/instr/Instrumenter.java b/org.jacoco.core/src/org/jacoco/core/instr/Instrumenter.java
index da956fd9..1b18f908 100644
--- a/org.jacoco.core/src/org/jacoco/core/instr/Instrumenter.java
+++ b/org.jacoco.core/src/org/jacoco/core/instr/Instrumenter.java
@@ -21,7 +21,6 @@ import java.util.zip.ZipEntry;
 import java.util.zip.ZipInputStream;
 import java.util.zip.ZipOutputStream;
 
-import org.jacoco.core.internal.BytecodeVersion;
 import org.jacoco.core.internal.ContentTypeDetector;
 import org.jacoco.core.internal.InputStreams;
 import org.jacoco.core.internal.Pack200Streams;
@@ -84,10 +83,7 @@ public class Instrumenter {
 
 	private byte[] instrument(final byte[] source) {
 		final long classId = CRC64.classId(source);
-		final int originalVersion = BytecodeVersion.get(source);
-		final byte[] b = BytecodeVersion.downgradeIfNeeded(originalVersion,
-				source);
-		final ClassReader reader = new ClassReader(b);
+		final ClassReader reader = new ClassReader(source);
 		final ClassWriter writer = new ClassWriter(reader, 0) {
 			@Override
 			protected String getCommonSuperClass(final String type1,
@@ -97,13 +93,12 @@ public class Instrumenter {
 		};
 		final IProbeArrayStrategy strategy = ProbeArrayStrategyFactory
 				.createFor(classId, reader, accessorGenerator);
+		final int version = InstrSupport.getVersionMajor(source);
 		final ClassVisitor visitor = new ClassProbesAdapter(
 				new ClassInstrumenter(strategy, writer),
-				InstrSupport.needsFrames(originalVersion));
+				InstrSupport.needsFrames(version));
 		reader.accept(visitor, ClassReader.EXPAND_FRAMES);
-		final byte[] instrumented = writer.toByteArray();
-		BytecodeVersion.set(instrumented, originalVersion);
-		return instrumented;
+		return writer.toByteArray();
 	}
 
 	/**
diff --git a/org.jacoco.core/src/org/jacoco/core/internal/BytecodeVersion.java b/org.jacoco.core/src/org/jacoco/core/internal/BytecodeVersion.java
deleted file mode 100644
index c24828b3..00000000
--- a/org.jacoco.core/src/org/jacoco/core/internal/BytecodeVersion.java
+++ /dev/null
@@ -1,81 +0,0 @@
-/*******************************************************************************
- * Copyright (c) 2009, 2018 Mountainminds GmbH & Co. KG and Contributors
- * All rights reserved. This program and the accompanying materials
- * are made available under the terms of the Eclipse Public License v1.0
- * which accompanies this distribution, and is available at
- * http://www.eclipse.org/legal/epl-v10.html
- *
- * Contributors:
- *    Evgeny Mandrikov - initial API and implementation
- *
- *******************************************************************************/
-package org.jacoco.core.internal;
-
-import org.objectweb.asm.Opcodes;
-
-/**
- * Utilities to read and modify bytecode version in bytes of class. Main purpose
- * of this class is to deal with bytecode versions which are not yet supported
- * by ASM.
- */
-public final class BytecodeVersion {
-
-	private static final int VERSION_INDEX = 6;
-
-	/**
-	 * Version of the Java 10 class file format.
-	 */
-	public static final int V10 = Opcodes.V9 + 1;
-
-	private BytecodeVersion() {
-	}
-
-	/**
-	 * Gets major of bytecode version number from given bytes of class.
-	 * 
-	 * @param b
-	 *            bytes of class
-	 * @return version of bytecode
-	 */
-	public static int get(final byte[] b) {
-		return (short) (((b[VERSION_INDEX] & 0xFF) << 8)
-				| (b[VERSION_INDEX + 1] & 0xFF));
-	}
-
-	/**
-	 * Sets major of bytecode version in given bytes of class.
-	 *
-	 * @param b
-	 *            bytes of class
-	 * @param version
-	 *            version of bytecode to set
-	 */
-	public static void set(final byte[] b, final int version) {
-		b[VERSION_INDEX] = (byte) (version >>> 8);
-		b[VERSION_INDEX + 1] = (byte) version;
-	}
-
-	/**
-	 * Returns given bytes of class if its major bytecode version is less that
-	 * {@link #V10}, otherwise returns copy where major version set to
-	 * {@link Opcodes#V9}.
-	 * 
-	 * @param version
-	 *            version of bytecode
-	 * @param source
-	 *            bytes of class
-	 * @return given bytes of class if version is less than {@link #V10},
-	 *         otherwise copy where version set to {@link Opcodes#V9}
-	 */
-	public static byte[] downgradeIfNeeded(final int version,
-			final byte[] source) {
-		if (V10 != version) {
-			return source;
-		}
-		final byte[] b = new byte[source.length];
-		System.arraycopy(source, 0, b, 0, source.length);
-		set(b, Opcodes.V9);
-		return b;
-	}
-
-}
diff --git a/org.jacoco.core/src/org/jacoco/core/internal/ContentTypeDetector.java b/org.jacoco.core/src/org/jacoco/core/internal/ContentTypeDetector.java
index c74d3374..5ef3a9a0 100644
--- a/org.jacoco.core/src/org/jacoco/core/internal/ContentTypeDetector.java
+++ b/org.jacoco.core/src/org/jacoco/core/internal/ContentTypeDetector.java
@@ -83,7 +83,7 @@ public class ContentTypeDetector {
 			case Opcodes.V1_7:
 			case Opcodes.V1_8:
 			case Opcodes.V9:
-			case BytecodeVersion.V10:
+			case Opcodes.V10:
 			case Opcodes.V11:
 			case Opcodes.V11 | Opcodes.V_PREVIEW_EXPERIMENTAL:
 			case Opcodes.V12:
diff --git a/org.jacoco.core/src/org/jacoco/core/internal/instr/InstrSupport.java b/org.jacoco.core/src/org/jacoco/core/internal/instr/InstrSupport.java
index 1d4cf2a3..c4569c28 100644
--- a/org.jacoco.core/src/org/jacoco/core/internal/instr/InstrSupport.java
+++ b/org.jacoco.core/src/org/jacoco/core/internal/instr/InstrSupport.java
@@ -13,6 +13,7 @@ package org.jacoco.core.internal.instr;
 
 import static java.lang.String.format;
 
+import org.objectweb.asm.ClassReader;
 import org.objectweb.asm.MethodVisitor;
 import org.objectweb.asm.Opcodes;
 
@@ -157,6 +158,20 @@ public final class InstrSupport {
 	 */
 	static final int CLINIT_ACC = Opcodes.ACC_SYNTHETIC | Opcodes.ACC_STATIC;
 
+	private static final int MAJOR_VERSION_INDEX = 6;
+
+	/**
+	 * Gets major of bytecode version number from given bytes of class.
+	 *
+	 * @param b
+	 *            bytes of class
+	 * @return version of bytecode
+	 */
+	public static int getVersionMajor(final byte[] b) {
+		return (short) (((b[MAJOR_VERSION_INDEX] & 0xFF) << 8)
+				| (b[MAJOR_VERSION_INDEX + 1] & 0xFF));
+	}
+
 	/**
 	 * Determines whether the given class file version requires stackmap frames.
 	 * 
diff --git a/org.jacoco.core/src/org/jacoco/core/internal/instr/ProbeArrayStrategyFactory.java b/org.jacoco.core/src/org/jacoco/core/internal/instr/ProbeArrayStrategyFactory.java
index a4fb82b0..4e1938f2 100644
--- a/org.jacoco.core/src/org/jacoco/core/internal/instr/ProbeArrayStrategyFactory.java
+++ b/org.jacoco.core/src/org/jacoco/core/internal/instr/ProbeArrayStrategyFactory.java
@@ -11,7 +11,6 @@
  *******************************************************************************/
 package org.jacoco.core.internal.instr;
 
-import org.jacoco.core.internal.BytecodeVersion;
 import org.jacoco.core.internal.flow.ClassProbesAdapter;
 import org.jacoco.core.runtime.IExecutionDataAccessorGenerator;
 import org.objectweb.asm.ClassReader;
@@ -44,7 +43,7 @@ public final class ProbeArrayStrategyFactory {
 			final IExecutionDataAccessorGenerator accessorGenerator) {
 
 		final String className = reader.getClassName();
-		final int version = BytecodeVersion.get(reader.b);
+		final int version = InstrSupport.getVersionMajor(reader.b);
 
 		if (isInterfaceOrModule(reader)) {
 			final ProbeCounter counter = getProbeCounter(reader);
diff --git a/org.jacoco.core/src/org/jacoco/core/runtime/ModifiedSystemClassRuntime.java b/org.jacoco.core/src/org/jacoco/core/runtime/ModifiedSystemClassRuntime.java
index e51242d8..6d31358f 100644
--- a/org.jacoco.core/src/org/jacoco/core/runtime/ModifiedSystemClassRuntime.java
+++ b/org.jacoco.core/src/org/jacoco/core/runtime/ModifiedSystemClassRuntime.java
@@ -19,7 +19,6 @@ import java.lang.instrument.Instrumentation;
 import java.lang.reflect.Field;
 import java.security.ProtectionDomain;
 
-import org.jacoco.core.internal.BytecodeVersion;
 import org.jacoco.core.internal.instr.InstrSupport;
 import org.objectweb.asm.ClassReader;
 import org.objectweb.asm.ClassVisitor;
@@ -154,10 +153,7 @@ public class ModifiedSystemClassRuntime extends AbstractRuntime {
 	 */
 	public static byte[] instrument(final byte[] source,
 			final String accessFieldName) {
-		final int originalVersion = BytecodeVersion.get(source);
-		final byte[] b = BytecodeVersion.downgradeIfNeeded(originalVersion,
-				source);
-		final ClassReader reader = new ClassReader(b);
+		final ClassReader reader = new ClassReader(source);
 		final ClassWriter writer = new ClassWriter(reader, 0);
 		reader.accept(new ClassVisitor(InstrSupport.ASM_API_VERSION, writer) {
 
@@ -168,9 +164,7 @@ public class ModifiedSystemClassRuntime extends AbstractRuntime {
 			}
 
 		}, ClassReader.EXPAND_FRAMES);
-		final byte[] instrumented = writer.toByteArray();
-		BytecodeVersion.set(instrumented, originalVersion);
-		return instrumented;
+		return writer.toByteArray();
 	}
 
 	private static void createDataField(final ClassVisitor visitor,