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/*
* Copyright (c) 2012, 2025, 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 vm.compiler.coverage.parentheses.share;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodHandles.Lookup;
import java.lang.reflect.Field;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.MethodVisitor;
import static org.objectweb.asm.Opcodes.*;
import java.lang.reflect.Method;
import java.util.List;
/**
* This class convert instructions sequence to java class file, load it to same JVM and then execute.
* This class uses hidden classes for class loading
*/
public class HotspotInstructionsExecutor implements InstructionsExecutor {
private static final Object[] NO_CP_PATCHES = new Object[0];
private int stackSize;
public HotspotInstructionsExecutor(int stackSize) {
this.stackSize = stackSize;
}
@Override
public int execute(List<Instruction> instructions) throws ReflectiveOperationException {
Class execClass = generateClass(instructions);
Method execMethod = execClass.getMethod("exec");
return (Integer) execMethod.invoke(null);
}
private Class generateClass(List<Instruction> instructions) throws ReflectiveOperationException {
// Needs to be in the same package as the lookup class.
String classNameForASM = "vm/compiler/coverage/parentheses/share/ExecClass";
ClassWriter cw = new ClassWriter(0);
cw.visit(V1_1, ACC_PUBLIC, classNameForASM, null, "java/lang/Object", null);
// creates a MethodWriter for the 'main' method
MethodVisitor mw = cw.visitMethod(ACC_PUBLIC + ACC_STATIC, "exec", "()I", null, null);
for (Instruction instruction : instructions) {
mw.visitInsn(instruction.opCode);
}
mw.visitInsn(IRETURN);
mw.visitMaxs(stackSize, 2);
mw.visitEnd();
Lookup lookup = MethodHandles.lookup();
Class<?> hc = lookup.defineHiddenClass(cw.toByteArray(), false).lookupClass();
return hc;
}
}
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