/**
* Empties the method of all code (except for a return). This includes line numbers, exceptions,
* local variables, etc.
*/
public static void empty_method(MethodGen mg) {
mg.setInstructionList(new InstructionList(new RETURN()));
mg.removeExceptionHandlers();
mg.removeLineNumbers();
mg.removeLocalVariables();
mg.setMaxLocals();
}
private static void addTimer(ClassGen cgen, Method method) {
// set up the construction tools
InstructionFactory ifact = new InstructionFactory(cgen);
InstructionList ilist = new InstructionList();
ConstantPoolGen pgen = cgen.getConstantPool();
String cname = cgen.getClassName();
MethodGen wrapgen = new MethodGen(method, cname, pgen);
wrapgen.setInstructionList(ilist);
// rename a copy of the original method
MethodGen methgen = new MethodGen(method, cname, pgen);
cgen.removeMethod(method);
String iname = methgen.getName() + "_timing";
methgen.setName(iname);
cgen.addMethod(methgen.getMethod());
Type result = methgen.getReturnType();
// compute the size of the calling parameters
Type[] parameters = methgen.getArgumentTypes();
int stackIndex = methgen.isStatic() ? 0 : 1;
for (int i = 0; i < parameters.length; i++) {
stackIndex += parameters[i].getSize();
}
// save time prior to invocation
ilist.append(
ifact.createInvoke(
"java.lang.System",
"currentTimeMillis",
Type.LONG,
Type.NO_ARGS,
Constants.INVOKESTATIC));
ilist.append(InstructionFactory.createStore(Type.LONG, stackIndex));
// call the wrapped method
int offset = 0;
short invoke = Constants.INVOKESTATIC;
if (!methgen.isStatic()) {
ilist.append(InstructionFactory.createLoad(Type.OBJECT, 0));
offset = 1;
invoke = Constants.INVOKEVIRTUAL;
}
for (int i = 0; i < parameters.length; i++) {
Type type = parameters[i];
ilist.append(InstructionFactory.createLoad(type, offset));
offset += type.getSize();
}
ilist.append(ifact.createInvoke(cname, iname, result, parameters, invoke));
// store result for return later
if (result != Type.VOID) {
ilist.append(InstructionFactory.createStore(result, stackIndex + 2));
}
// print time required for method call
ilist.append(
ifact.createFieldAccess(
"java.lang.System", "out", new ObjectType("java.io.PrintStream"), Constants.GETSTATIC));
ilist.append(InstructionConstants.DUP);
ilist.append(InstructionConstants.DUP);
String text = "Call to method " + methgen.getName() + " took ";
ilist.append(new PUSH(pgen, text));
ilist.append(
ifact.createInvoke(
"java.io.PrintStream",
"print",
Type.VOID,
new Type[] {Type.STRING},
Constants.INVOKEVIRTUAL));
ilist.append(
ifact.createInvoke(
"java.lang.System",
"currentTimeMillis",
Type.LONG,
Type.NO_ARGS,
Constants.INVOKESTATIC));
ilist.append(InstructionFactory.createLoad(Type.LONG, stackIndex));
ilist.append(InstructionConstants.LSUB);
ilist.append(
ifact.createInvoke(
"java.io.PrintStream",
"print",
Type.VOID,
new Type[] {Type.LONG},
Constants.INVOKEVIRTUAL));
ilist.append(new PUSH(pgen, " ms."));
ilist.append(
ifact.createInvoke(
"java.io.PrintStream",
"println",
Type.VOID,
new Type[] {Type.STRING},
Constants.INVOKEVIRTUAL));
// return result from wrapped method call
if (result != Type.VOID) {
ilist.append(InstructionFactory.createLoad(result, stackIndex + 2));
}
ilist.append(InstructionFactory.createReturn(result));
// finalize the constructed method
wrapgen.stripAttributes(true);
wrapgen.setMaxStack();
wrapgen.setMaxLocals();
cgen.addMethod(wrapgen.getMethod());
ilist.dispose();
}
/**
* Processes each method in cg replacing any specified calls with static user calls.
*
* @param fullClassName must be packageName.className
*/
private boolean map_calls(ClassGen cg, String fullClassName, ClassLoader loader) {
boolean transformed = false;
try {
pgen = cg.getConstantPool();
// Loop through each method in the class
Method[] methods = cg.getMethods();
for (int i = 0; i < methods.length; i++) {
MethodGen mg = new MethodGen(methods[i], cg.getClassName(), pgen);
// Get the instruction list and skip methods with no instructions
InstructionList il = mg.getInstructionList();
if (il == null) continue;
if (debug) out.format("Original code: %s%n", mg.getMethod().getCode());
instrument_method(methods[i], mg);
// Remove the Local variable type table attribute (if any).
// Evidently, some changes we make require this to be updated, but
// without BCEL support, that would be hard to do. Just delete it
// for now (since it is optional, and we are unlikely to be used by
// a debugger)
for (Attribute a : mg.getCodeAttributes()) {
if (is_local_variable_type_table(a)) {
mg.removeCodeAttribute(a);
}
}
// Update the instruction list
mg.setInstructionList(il);
mg.update();
// Update the max stack and Max Locals
mg.setMaxLocals();
mg.setMaxStack();
mg.update();
// Update the method in the class
cg.replaceMethod(methods[i], mg.getMethod());
if (debug) out.format("Modified code: %s%n", mg.getMethod().getCode());
// verify the new method
// StackVer stackver = new StackVer();
// VerificationResult vr = stackver.do_stack_ver (mg);
// log ("vr for method %s = %s%n", mg.getName(), vr);
// if (vr.getStatus() != VerificationResult.VERIFIED_OK) {
// System.out.printf ("Warning BCEL Verify failed for method %s: %s",
// mg.getName(), vr);
// System.out.printf ("Code: %n%s%n", mg.getMethod().getCode());
// System.exit(1);
// }
}
cg.update();
} catch (Exception e) {
out.format("Unexpected exception encountered: " + e);
e.printStackTrace();
}
return transformed;
}
