[Soot-list] Add Expression works strange.

[Eric Bodden]

Thanks a lot for the input Elena!

Wow, that's odd! I have never seen javap give such apparently false/misleading information. Is this something we should report to Oracle?

Anyway, I would assume that the bytecode is actually correct?

Cheers,
Eric


> On 06.02.2015, at 01:22, Elena Sherman <elenasherman at boisestate.edu> wrote:
> 
> Roman,
> 
> I've run your code with the initialization of the local variable part added to it. It looks like that depending on the bytecode viewer I get different bytecode. When I use javap -c Decomp.class I get the following (what you get):
> 
> Compiled from "Decomp.java"
> public class decomp.Decomp {
>   public decomp.Decomp();
>     Code:
>        0: aload_0       
>        1: invokespecial #1                  // Method java/lang/Object."<init>":()V
>        4: return        
>        5: iconst_0      
>        6: istore_0      
>        7: iinc_w        #0,  1              // #0
> 
>   public static void main(java.lang.String[]);
>     Code:
>        0: return        
>        1: iconst_0      
>        2: istore_0      
>        3: iinc_w        #0,  1              // #0
> }
> 
> However, when I use Eclipse's bytecode viewer I get the following:
> 
> // Compiled from Decomp.java (version 1.2 : 46.0, super bit)
> public class decomp.Decomp {
>   // Method descriptor #12 ()V
>   // Stack: 1, Locals: 1
>   public Decomp();
>      0  aload_0 [this]
>      1  invokespecial java.lang.Object() [1]
>      4  return
>      5  wide
>      6  iinc 0 500 [this]
>       Line numbers:
>         [pc: 0, line: 0]
>         [pc: 1, line: 1]
>         [pc: 4, line: 2]
>         [pc: 5, line: 3]
>       Attribute: LineNumberTable Length: 18
>       Attribute: LineNumberTable Length: 18
> 
>   // Method descriptor #11 ([Ljava/lang/String;)V
>   // Stack: 0, Locals: 1
>   public static void main(java.lang.String[] arg0);
>     0  return
>     1  wide
>     2  iinc 0 500 [arg0]
>       Line numbers:
>         [pc: 0, line: 0]
>         [pc: 1, line: 1]
>       Attribute: LineNumberTable Length: 10
>       Attribute: LineNumberTable Length: 10
> }
> 
> Which is correct. So, apparently the wide incremental instruction, i.e., iinc_w should be interpreted a bit different than its regular version iinc. I'm not a bytecode specialist, so I cannot tell exactly how to interpret iinc_w's arguments in terms of iinc.
> 
> In general bytecode can be quite confusing, so in order to check whether your instrumentation works as expected try to print something out like the value of the local variable you're trying to increment. Thus when you execute the instrumented code you will know for sure if this is what you want or not, or there are any errors in the instrumentation.
> 
> Hope it helps.
> 
> Elena
> 
> On Thu, Feb 5, 2015 at 11:38 AM, Roman Petriev <vvpiroman at gmail.com> wrote:
> Test cases here.
> Is it good? Do you need anything else?
> 
> 2015-02-05 12:58 GMT+03:00 Bodden, Eric <eric.bodden at sit.fraunhofer.de>:
> Hi Roman.
> 
> > I hope that is (exactly) what you want to see.
> 
> Ideal would be a minimal but runnable example, including your driver class for Soot and the command-line options you are using. We should be able to reproduce this with as little effort as possible.
> 
> Thanks,
> Eric
> 
> 

--
Prof. Eric Bodden, Ph.D., http://sse.ec-spride.de/ http://bodden.de/
Head of Secure Software Engineering at Fraunhofer SIT, TU Darmstadt and EC SPRIDE
Tel: +49 6151 16-75422    Fax: +49 6151 869-127
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