Java GeneratorAdapter.loadLocal方法代碼示例

import org.objectweb.asm.commons.GeneratorAdapter; //導入方法依賴的package包/類
/**
 * Adds the instructions to do a generic redirection.
 */
protected void redirect(GeneratorAdapter mv, int change) {
    // code to check if a new implementation of the current class is available.
    Label l0 = new Label();
    mv.loadLocal(change);
    mv.visitJumpInsn(Opcodes.IFNULL, l0);
    doRedirect(mv, change);

    // Return
    if (type == Type.VOID_TYPE) {
        mv.pop();
    } else {
        ByteCodeUtils.unbox(mv, type);
    }
    mv.returnValue();

    // jump label for classes without any new implementation, just invoke the original
    // method implementation.
    mv.visitLabel(l0);
}
 

import org.objectweb.asm.commons.GeneratorAdapter; //導入方法依賴的package包/類
@Override
protected void doRedirect( GeneratorAdapter mv, int change) {
    mv.loadLocal(change);
    mv.push(AcesoProguardMap.instance().getMtdIndex(visitedClassName, IncrementalTool.getMtdSig(mtdName,mtdDesc)));
    ByteCodeUtils.newVariableArray(mv, ByteCodeUtils.toLocalVariables(types));

    // now invoke the generic dispatch method.
    mv.invokeInterface(IncrementalVisitor.CHANGE_TYPE, Method.getMethod("Object access$dispatch(int, Object[])"));
}
 

import org.objectweb.asm.commons.GeneratorAdapter; //導入方法依賴的package包/類
/**
 * Adds the instructions to do a generic redirection.
 * <p/>
 * Note that the generated bytecode does not have a direct translation to code, but as an
 * example, the following code block gets inserted.
 * <code>
 * if ($change != null) {
 * $change.access$dispatch($name, new object[] { arg0, ... argsN })
 * $anyCodeInsertedbyRestore
 * }
 * $originalMethodBody
 * </code>
 *
 * @param mv     the method visitor to add the instructions to.
 * @param change the local variable containing the alternate implementation.
 * @param args   the type of the local variable that need to be forwarded.
 */
void redirect(GeneratorAdapter mv, int change, List<Type> args) {
    // code to check if a new implementation of the current class is available.
    Label l0 = new Label();
    mv.loadLocal(change);
    mv.visitJumpInsn(Opcodes.IFNULL, l0);
    mv.loadLocal(change);
    mv.push(name);

    // create an array of objects capable of containing all the parameters and optionally the "this"
    createLocals(mv, args);

    // we need to maintain the stack index when loading parameters from, as for long and double
    // values, it uses 2 stack elements, all others use only 1 stack element.
    int stackIndex = 0;
    for (int arrayIndex = 0; arrayIndex < args.size(); arrayIndex++) {
        Type arg = args.get(arrayIndex);
        // duplicate the array of objects reference, it will be used to store the value in.
        mv.dup();
        // index in the array of objects to store the boxed parameter.
        mv.push(arrayIndex);
        // Pushes the appropriate local variable on the stack
        redirectLocal(mv, stackIndex, arg);
        // potentially box up intrinsic types.
        mv.box(arg);
        mv.arrayStore(Type.getType(Object.class));
        // stack index must progress according to the parameter type we just processed.
        stackIndex += arg.getSize();
    }

    // now invoke the generic dispatch method.
    mv.invokeInterface(IncrementalVisitor.CHANGE_TYPE, Method.getMethod("Object access$dispatch(String, Object[])"));

    // Restore the state after the redirection
    restore(mv, args);
    // jump label for classes without any new implementation, just invoke the original
    // method implementation.
    mv.visitLabel(l0);
}
 

import org.objectweb.asm.commons.GeneratorAdapter; //導入方法依賴的package包/類
@Override
protected void redirectLocal(GeneratorAdapter mv, int stackIndex, Type arg) {
    // If the stack index is 0, we do not send the local variable 0 (this) as it
    // cannot escape the constructor. Instead, we use this argument position to send
    // a reference to the locals array where the redirected method will return their
    // values.
    if (stackIndex == 0) {
        mv.loadLocal(locals);
    } else {
        super.redirectLocal(mv, stackIndex, arg);
    }
}
 

import org.objectweb.asm.commons.GeneratorAdapter; //導入方法依賴的package包/類
@Override
protected void restore(GeneratorAdapter mv, List<Type> args) {
    // At this point, init$args has been called and the result Object is on the stack.
    // The value of that Object is Object[] with exactly n + 1 elements.
    // The first element is a string with the qualified name of the constructor to call.
    // The remaining elements are the constructtor arguments.

    // Create a new local that holds the result of init$args call.
    mv.visitTypeInsn(Opcodes.CHECKCAST, "[Ljava/lang/Object;");
    int constructorArgs = mv.newLocal(Type.getType("[Ljava/lang/Object;"));
    mv.storeLocal(constructorArgs);

    // Reinstate local values
    mv.loadLocal(locals);
    int stackIndex = 0;
    for (int arrayIndex = 0; arrayIndex < args.size(); arrayIndex++) {
        Type arg = args.get(arrayIndex);
        // Do not restore "this"
        if (arrayIndex > 0) {
            // duplicates the array
            mv.dup();
            // index in the array of objects to restore the boxed parameter.
            mv.push(arrayIndex);
            // get it from the array
            mv.arrayLoad(Type.getType(Object.class));
            // unbox the argument
            ByteCodeUtils.unbox(mv, arg);
            // restore the argument
            mv.visitVarInsn(arg.getOpcode(Opcodes.ISTORE), stackIndex);
        }
        // stack index must progress according to the parameter type we just processed.
        stackIndex += arg.getSize();
    }
    // pops the array
    mv.pop();

    // Push a null for the marker parameter.
    mv.loadLocal(constructorArgs);
    mv.visitInsn(Opcodes.ACONST_NULL);

    // Invoke the constructor
    mv.visitMethodInsn(Opcodes.INVOKESPECIAL, thisClassName, "<init>", DISPATCHING_THIS_SIGNATURE, false);

    mv.goTo(end.getLabel());
}