bytecode

问题 Closed . This question needs to be more focused. It is not currently accepting answers. Want to improve this question? Update the question so it focuses on one problem only by editing this post. Closed 4 years ago . I am recently reading about bytecode analysis and I need a help with the below query: Which JDK packages/APIs I have to look for if I wanted to write a Java program which disassembles a Java Byte Code (by reading a class file) and print Opcodes without using any external libraries

问题 Though a switch statement can be represented as a series of if statements, it appears that when a Java switch statement is compiled into bytecode, a different approach is used. What is the representation used by bytecode? I assume this alternate representation is for efficiency reasons, so how does the efficiency compare to that of just an if statement representation? Are there any other considerations that have led to using this representation? 回答1: Read the spec . In Java, if you code a

问题 When I wrote some code, I found a interesting thing: def test(): l = [] for i in range(10): def f():pass print(f) #l.append(f) test() import dis dis.dis(test) The output is : <function test.<locals>.f at 0x7f46c0b0d400> <function test.<locals>.f at 0x7f46c0b0d488> <function test.<locals>.f at 0x7f46c0b0d400> <function test.<locals>.f at 0x7f46c0b0d488> <function test.<locals>.f at 0x7f46c0b0d400> <function test.<locals>.f at 0x7f46c0b0d488> <function test.<locals>.f at 0x7f46c0b0d400>

问题 I'm using a Java Agent and Javassist to add some logging to some JDK classes. Essentially when the system loads some TLS classes, Javassist will add some additional bytecode to them to help me debug some connection problems. Here's the problem, given this class is included in the agent jar: package com.something.myagent; public class MyAgentPrinter { public static final void sayHello() { System.out.println("Hello!"); } } In my agent's transform method, let's say I tried to invoke that class

问题 I looked at the internal representation of some OCaml values. The representation of an empty array is an atom(0) , i.e. a block with tag=0 and size=0 . Empty arrays of floats are represented by an atom(0) too. Is there any OCaml value represented by an atom with tag > 0 ? If not: for what purpose the OCaml bytecode set contains the ATOM n instruction? 回答1: A tag > 0 is used for constructors with arguments, which would make them not atoms. Constructors without arguments on the other hand are

问题 I am looking for a high level bytecode manipulation tool like Javassist, but that understands some of Scala peculiarities. Lower level bytecode manipulation tools should be relatively agnostic, but for my use cases something at the level of Javassist is much better. However a tool at that level needs to know about the source language and its bytecode mapping. Does something like this exist for Scala? So far I have been able to use Javassist with Scala for very simple things, but I have been

问题 I would like to open a PE file (which i know is a .Net assembly) and find where the .Net bytecode is (ideally starting at the entrypoint). I know that the PE header data (entrypoint RVA) take me just to a stub which calls CorExeMain from mscoree.dll . This is not what i'm looking for though. I would like to find the bytecode that gets run by mscorlib. How can i do that using C++ and no external tools like ildasm, dumpbin etc. ? I can already parse the PE header and know what image base/RVA

问题 You see assembly code and assembly coders all over the internet but there's almost nothing on bytecode. Why is that ? The needs and the advantages of programming in assembly should all hold for programming in bytecode too. 回答1: Another reason why bytecode programming is far less popular / common than assembly programming is the genericity of bytecode - its simplicity. Bytecode instruction sets are largely "ultra-RISC", very simple instructions. Designed for two purposes, to provide the

问题 I want to understand class files and inner/nested classes a bit better and I'm wondering about the following things: Is the InnerClasses attribute used to refer tothe inner/nested classes in the ´containing´ class or is it used in the inner/nested classes to refer to the ‘container’ class? Is the InnerClasses attribute in class files sufficient? E.g. Do inner/nested classes have to follow the name mangling with $ or is this just a convention? Is there a way to make a class look like an inner

问题 I'm enrolled in a compilers course, using the "dragon book" as textbook. It gives instructions on how to convert the intermediate code generated by its compiler to an object language, assembly. My question is: where can I find instructions to convert an intermediate code in the 3-address format to java bytecode, for the same grammar used in the book? Textbook site: http://dragonbook.stanford.edu/index.html#courses 回答1: If you want to know how to create a binary Java classfile yourself, there