Java CodeAttribute.setMaxLocals方法代码示例

import scouter.javassist.bytecode.CodeAttribute; //导入方法依赖的package包/类
/**
 * Declares a new local variable.  The scope of this variable is the
 * whole method body.  The initial value of that variable is not set.
 * The declared variable can be accessed in the code snippet inserted
 * by <code>insertBefore()</code>, <code>insertAfter()</code>, etc.
 *
 * <p>If the second parameter <code>asFinally</code> to
 * <code>insertAfter()</code> is true, the declared local variable
 * is not visible from the code inserted by <code>insertAfter()</code>.
 *
 * @param name      the name of the variable
 * @param type      the type of the variable
 * @see #insertBefore(String)
 * @see #insertAfter(String)
 */
public void addLocalVariable(String name, CtClass type)
    throws CannotCompileException
{
    declaringClass.checkModify();
    ConstPool cp = methodInfo.getConstPool();
    CodeAttribute ca = methodInfo.getCodeAttribute();
    if (ca == null)
        throw new CannotCompileException("no method body");

    LocalVariableAttribute va = (LocalVariableAttribute)ca.getAttribute(
                                            LocalVariableAttribute.tag);
    if (va == null) {
        va = new LocalVariableAttribute(cp);
        ca.getAttributes().add(va);
    }

    int maxLocals = ca.getMaxLocals();
    String desc = Descriptor.of(type);
    va.addEntry(0, ca.getCodeLength(),
                cp.addUtf8Info(name), cp.addUtf8Info(desc), maxLocals);
    ca.setMaxLocals(maxLocals + Descriptor.dataSize(desc));
}
 

import scouter.javassist.bytecode.CodeAttribute; //导入方法依赖的package包/类
protected void runEditor(ExprEditor ed, CodeIterator oldIterator)
    throws CannotCompileException
{
    CodeAttribute codeAttr = oldIterator.get();
    int orgLocals = codeAttr.getMaxLocals();
    int orgStack = codeAttr.getMaxStack();
    int newLocals = locals();
    codeAttr.setMaxStack(stack());
    codeAttr.setMaxLocals(newLocals);
    ExprEditor.LoopContext context
        = new ExprEditor.LoopContext(newLocals);
    int size = oldIterator.getCodeLength();
    int endPos = oldIterator.lookAhead();
    oldIterator.move(currentPos);
    if (ed.doit(thisClass, thisMethod, context, oldIterator, endPos))
        edited = true;

    oldIterator.move(endPos + oldIterator.getCodeLength() - size);
    codeAttr.setMaxLocals(orgLocals);
    codeAttr.setMaxStack(orgStack);
    maxLocals = context.maxLocals;
    maxStack += context.maxStack;
}
 

import scouter.javassist.bytecode.CodeAttribute; //导入方法依赖的package包/类
/**
 * Performs code conversion.
 */
protected void doit(CtClass clazz, MethodInfo minfo, ConstPool cp)
    throws CannotCompileException
{
   Transformer t;
    CodeAttribute codeAttr = minfo.getCodeAttribute();
    if (codeAttr == null || transformers == null)
        return;
    for (t = transformers; t != null; t = t.getNext())
        t.initialize(cp, clazz, minfo);

    CodeIterator iterator = codeAttr.iterator();
    while (iterator.hasNext()) {
        try {
            int pos = iterator.next();
            for (t = transformers; t != null; t = t.getNext())
                pos = t.transform(clazz, pos, iterator, cp);
        }
        catch (BadBytecode e) {
            throw new CannotCompileException(e);
        }
    }

    int locals = 0;
    int stack = 0;
    for (t = transformers; t != null; t = t.getNext()) {
        int s = t.extraLocals();
        if (s > locals)
            locals = s;

        s = t.extraStack();
        if (s > stack)
            stack = s;
    }

    for (t = transformers; t != null; t = t.getNext())
        t.clean();

    if (locals > 0)
        codeAttr.setMaxLocals(codeAttr.getMaxLocals() + locals);

    if (stack > 0)
        codeAttr.setMaxStack(codeAttr.getMaxStack() + stack);

    try {
    	minfo.rebuildStackMapIf6(clazz.getClassPool(),
                                 clazz.getClassFile2());
    }
    catch (BadBytecode b) {
        throw new CannotCompileException(b.getMessage(), b);
    }
}
 

import scouter.javassist.bytecode.CodeAttribute; //导入方法依赖的package包/类
/**
 * Undocumented method.  Do not use; internal-use only.
 */
public boolean doit(CtClass clazz, MethodInfo minfo)
    throws CannotCompileException
{
    CodeAttribute codeAttr = minfo.getCodeAttribute();
    if (codeAttr == null)
        return false;

    CodeIterator iterator = codeAttr.iterator();
    boolean edited = false;
    LoopContext context = new LoopContext(codeAttr.getMaxLocals());

    while (iterator.hasNext())
        if (loopBody(iterator, clazz, minfo, context))
            edited = true;

    ExceptionTable et = codeAttr.getExceptionTable();
    int n = et.size();
    for (int i = 0; i < n; ++i) {
        Handler h = new Handler(et, i, iterator, clazz, minfo);
        edit(h);
        if (h.edited()) {
            edited = true;
            context.updateMax(h.locals(), h.stack());
        }
    }

    // codeAttr might be modified by other partiess
    // so I check the current value of max-locals.
    if (codeAttr.getMaxLocals() < context.maxLocals)
        codeAttr.setMaxLocals(context.maxLocals);

    codeAttr.setMaxStack(codeAttr.getMaxStack() + context.maxStack);
    try {
        if (edited)
            minfo.rebuildStackMapIf6(clazz.getClassPool(),
                                     clazz.getClassFile2());
    }
    catch (BadBytecode b) {
        throw new CannotCompileException(b.getMessage(), b);
    }

    return edited;
}