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modifying python bytecode

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问题 I was wondering how to modify byte code, then recompile that code so I can use it in python as a function? I've been trying: a = """ def fact(): a = 8 a = 0 """ c = compile(a, '<string>', 'exec') w = c.co_consts[0].co_code dis(w) which decompiles to: 0 LOAD_CONST 1 (1) 3 STORE_FAST 1 (1) 6 LOAD_CONST 2 (2) 9 STORE_FAST 1 (1) 12 LOAD_CONST 0 (0) 15 RETURN_VALUE supposing I want to get rid of lines 0 and 3, I call: x = c.co_consts[0].co_code[6:16] dis(x) which results in : 0 LOAD_CONST 2 (2) 3

Is it possible to inject code in an android application?

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问题 I would like to inject code in an android application at runtime. I have tried to use dx tool to generate a dexfile in the sdcard but when i want to instantiate, it fails. Are there any tools to inject code generating new dalvik bytecode? I am studing some libraries, aspecjt or guice for android. Is it better to work with a script language? Thanks people :) 回答1: No, it is not possible. Android application permissions would not work if that was possible. 回答2: Dexmaker is new and designed just

Different behaviour of java bytecode

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I am a newbee in Java Bytecode. I was understanding the bytecode through some examples but I got stuck in an example. These are my java and bytecode file class SimpleAdd{ public static void main(char args[]){ int a,b,c,d; a = 9; b = 4; c = 3; d = a + b + c; System.out.println(d); } } Compiled from "SimpleAdd.java" class SimpleAdd extends java.lang.Object{ SimpleAdd(); Code: 0: aload_0 1: invokespecial #1; //Method java/lang/Object."<init>":()V 4: return public static void main(char[]); Code: 0: bipush 9 2: istore_1 3: iconst_4 4: istore_2 5: iconst_3 6: istore_3 7: iload_1 8: iload_2 9: iadd

Why isn't more Java software compiled natively?

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I realize the benefits of bytecode vs. native code (portability). But say you always know that your code will run on a x86 architecture, why not then compile for x86 and get the performance benefit? Note that I am assuming there is a performance gain to native code compilation. Some folks have answered that there could in fact be no gain which is news to me.. Because the performance gain (if any) is not worth the trouble. Also, garbage collection is very important for performance. Chances are that the GC of the JVM is better than the one embedded in the compiled executable, say with GCJ . And

Writing a detector to search for uses of “System.out.println” using Findbugs

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问题 I am trying to write a bug detector to find instances of the method call "System.out.println" using Findbugs. I understand that "System.out.println" in bytecode is compiled to a call to GETSTATIC, which pushes "System.out" onto the stack. A call to INVOKEVIRTUAL pops "System.out" off the stack and calls the method. I have prepared some code (found below) which finds the correct GETSTATIC and INVOKEVIRTUAL calls, but have been unable to link the two together. I suspect I may need to use

Do different Java Compilers (where the vendor is different) produce different bytecode

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问题 Given the same major version, say Java 7, do different Java Compilers (e.g., Oracle's hotspot, JRockit, or IBM's J9 etc...) compile a given java source code file into the same bytcode? Scanning the Java 7 language spec it would seem that what is being discussed is the semantics of the language and not the transformation of the code into bytecode. This question is not the same as do different major.minor versions for a given vendor produce the same bytecode. That question is already answered

Methodologies for designing a simple programming language

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问题 In my ongoing effort to quench my undying thirst for more programming knowledge I have come up with the idea of attempting to write a (at least for now) simple programming language that compiles into bytecode. The problem is I don't know the first thing about language design. Does anyone have any advice on a methodology to build a parser and what the basic features every language should have? What reading would you recommend for language design? How high level should I be shooting for? Is it

How does Java Determine methods call at runtime in polymorphism?

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问题 While the main principle of polymorphism is decoupling "what from who" in term of types , but what confuses me how does method-call mechanism finds out and calls the correct method body in polymorphism. Since in java all method binding is late-binding unless the method is static , final or private , and late-binding is done by JVM which precomputes method table for each class and then do a table look up during runtime in normal method call. But the same thing happens during polymorphism too.

Disabling compile-time dependency checking when compiling Java classes

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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 compile and javac will give you the error message "package pkg.not.in.classpath does not exist" . The error message is nice in the general case since checking your dependencies allows the compiler to tell you if you got some method argument wrong, etc. While nice and

Lua's bytecode specification [closed]

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Can anyone tell me where to find Lua's bytecode specification? I've been searching for 15 minutes, and I can't find anything . Maybe A No-Frills Introduction to Lua 5.1 VM Instructions contains what you're looking for? There is also a table of the Lua 5.0 instruction set (Figure 5) in: Ierusalimschy, R.; Figueiredo, L. H.; Celes, W. (2005), "The implementation of Lua 5.0", J. of Universal Comp. Sci. 11 (7): 1159-1176 You can find the full text with a search on Google Scholar and I believe it's on lua.org as well. This reference is used by the Lua page on Wikipedia, which is always a good place