How are strings embedded in binary files?
I'm writing my own bytecode and virtual machine (on .NET) and one thing i can't figure out is how to embed strings into my bytecode. Any ideas now how i should do it? ...
bytecode
Fail-safe way of round-tripping JVM byte-code to text-representation and back
I'm looking for a fail-safe way to round-trip between a JVM class file and a text representation and back again. One strict requirement is that the resulting round-tripped JVM class file is exactly functionally equivalent to the original JVM class file as long as the text representation is left unchanged. Furthermore, the text represen...
Is Java bytecode compatible within different updates of the same version of Java?
Hello, this question is related to the the other topic discussed here: http://stackoverflow.com/questions/1266940/is-java-bytecode-compatible-with-different-versions-of-java but in this case would like to know whether compatibility is preserved within the same version but on different updates. For example, is bytecode generate by the com...
Lua's bytecode specification
Can anyone tell me where to find Lua's bytecode specification? I've been searching for 15 minutes, and I can't find anything. ...
Is there any way to programmatically generate Python bytecode?
I want to hack around with the Python interpreter and try creating a small DSL . Is there any module where I can do something like this theoretical code (similar to LINQ expression trees)? expression_tree = Function( Print( String('Hello world!') ) ) compile_to_bytecode(expression_tree) Or would it just be easier t...
Scala in java code : $colon
Hi, I read some java source code which including Scala source code. I found Nil.$colon$colon(Object arg) What does keywords $colon mean? And what does this line mean? ...
Switching between bytecode versions for a Java class file
Given a Java class file (ClassName.class) with bytecode version X is there a general way to convert this class file from being represented in bytecode version X to being represented in bytecode version Y? Assumptions: The source code is not available. The class file is the only available representation of the class. The class file is ...
Disabling compile-time dependency checking when compiling Java classes
Consider the following two Java classes: a.) class Test { void foo(Object foobar) { } } b.) class Test { void foo(pkg.not.in.classpath.FooBar foobar) { } } Furthermore, assume that pkg.not.in.classpath.FooBar is not found in the classpath. The first class will compile fine using the standard javac. However, the second class won't c...
Understanding Java Byte Code
Often I am stuck with a java class file with no source and I am trying to understand the problem I have at hand. Note a decompiler is useful but not sufficient in all situation... I have two question What tools are available to view java byte code (preferably available from the linux command line ) What are good references to get fam...
unboxing using the ASM Java library
I'm using the ASM Java library to replace some reflection. I generate the body of this method: void set(Object object, int fieldIndex, Object value); With this generated method, I can set fields on an object at runtime without using reflection. It works great. However, I found it fails for primitive fields. Here is the relevant part o...
CPython is bytecode interpreter?
I don't really get the concept of "bytecode interpreter" in the context of CPython. Can someone shed some light over the whole picture? Does it mean that CPython will compile and execute pyc file (bytecode file?). Then what compile py file to pyc file? And how is Jython different from CPython (except they are implemented in different la...
Resolve class name from bytecode
Is it possible to dig up a classes name from bytecode which is formed from the class' source code? The situation is this: I get a classes bytecode remotely from somewhere, it doesn't matter where it comes from. To effectively load that class with a classloader i would need to have the class name as well... right? ...
In the 13 years that Java has been around, are there any specific examples of backward incompatibilities?
It has been thirteen years between the initial public release of Java 1.0 (1996) and the current stable release 1.6.0_16 (2009). During those thirteen years the following notable releases have been made: JDK 1.0 (January, 1996) JDK 1.1 (February, 1997) J2SE 1.2 (December, 1998) J2SE 1.3 (May, 2000) J2SE 1.4 (February, 2002) J2SE 5.0 (...
Compiler optimization: Java bytecode
I'm currently writing a toy compiler targeting Java bytecode in the translation. I would like to know if there is some kind of catalog, maybe a summary, of various simple peephole optimizations that can be made in the emitted bytecode before writing the .class file. I actually am aware of some libraries that have this functionality, but...
What are some interesting, free, open-source Dynamic Analysis tools for Java?
I am looking for some interesting dynamic analysers to use and report on for a university assignment. The tools should be: Open-source (so I can learn from them) Free (both as in speech and beer, because I want to be able to share the results, and I'm tight-fisted, respectively) Intended for Java (source or bytecode) This includes, b...
What is the use of Python's basic optimizations mode? (`python -O`)
Python has a flag -O that you can execute the interpreter with. The option will generate "optimized" bytecode (written to .pyo files), and given twice, it will discard docstrings. From Python's man page: -O Turn on basic optimizations. This changes the filename exten‐ sion for compiled (bytecode) files from .pyc ...
How to determine the Java byte code version of the current class programatically?
I have a situation where the deployment platform is Java 5 and the development happens with Eclipse under Java 6 where we have established a procedure of having a new workspace created when beginning work on a given project. One of the required steps is therefore setting the compiler level to Java 5, which is frequently forgotten. We h...
What is ILLegal Byte code ?
While reading Java Security I came across the below sentences but could not get any satisfactory explanation on the Internet. Can anyone please explain Prevents loading of classes with bytecode Prevents loading of in illegal packages ...
Local variables in java bytecode
I am trying to learn java bytecode and I stumbled on this: I compiled this very simple code with the -g option: public class Test { public static void main(String args[]) { double a = 1.0; int b = (int)a; } } The main code turned out to be: 0 dconst_1 1 dstore_1 2 dload_1 3 d2i 4 istore_3 5 return In addition, main's maximum...
What is the difference between assembly code and bytecode?
While in the search for the various differences in the meanings of source code, bytecode, assembly code, machine code, compilers, linkers, interpreters, assemblers and all the rest, I only got confused on the difference between bytcode and assembly code. Particularly the introduction this wikipedia article to describe CIL confused me ...