[Soot-list] Possible bug with null-type locals

[Rohan Padhye]

Hello Eric,

I am using the the JAR from http://plg.uwaterloo.ca/~olhotak/build ... 
Is this is
the correct place to get the nightly build? It says so on the Soot website.

And yes, I tried with the same command arguments that you did:
$ javac BugTest.java
$ java -jar sootclasses.jar -cp . -pp -f J BugTest

.... And I'm still getting the output that I posted earlier.

Regards,
Rohan

PS: I don't have any of the other JARs (such as Polyglot, Jasmin, etc) 
if that makes
any difference.

On Monday 04 March 2013 08:22 PM, Eric Bodden wrote:
> Thanks a lot Rohan, that's quite useful.
>
> Unfortunately I am unable to reproduce this bug. Using the command
> line arguments "-cp . -pp BugTest -f J" I am getting this input with
> my version of Soot (which should correspond to the current development
> branch and thus the nightly build). What command line are you using?
>
> public class BugTest extends java.lang.Object
> {
>
>      public void <init>()
>      {
>          BugTest r0;
>
>          r0 := @this: BugTest;
>          specialinvoke r0.<java.lang.Object: void <init>()>();
>          return;
>      }
>
>      public static void main(java.lang.String[])
>      {
>          java.lang.String[] r0;
>          Node r1, r2, $r3;
>          int i0;
>
>          r0 := @parameter0: java.lang.String[];
>          r1 = null;
>          i0 = 0;
>          goto label1;
>
>       label0:
>          $r3 = new Node;
>          specialinvoke $r3.<Node: void <init>()>();
>          r2 = $r3;
>          r2.<Node: Node n> = r1;
>          r1 = r2;
>          i0 = i0 + 1;
>
>       label1:
>          if i0 < 5 goto label0;
>
>          return;
>      }
> }
>
> Eric
>
>
> On 4 March 2013 14:32, Rohan Padhye <rohanpadhye at cse.iitb.ac.in> wrote:
>> Hi,
>>
>> I have come across what seems to be a bug in the nightly build.
>>
>> Consider a simple program constructing a linked-list of five elements:
>>
>> class Node
>> {
>>       Node n;
>> }
>> class BugTest
>> {
>>       public static void main(String args[])
>>       {
>>           Node x = null;
>>           for(int i=0; i<5; i++) {
>>               Node t = new Node();
>>               t.n = x;
>>               x = t;
>>           }
>>       }
>> }
>>
>>
>> For some reason Soot builds the following Jimple: (Note the Jimple for
>> the line "t.n = x")
>>
>> public static void main(java.lang.String[])
>>       {
>>           java.lang.String[] r0;
>>           null_type n0;
>>           byte b0;
>>           Node r1, $r2, r3;
>>           int i1;
>>
>>           r0 := @parameter0: java.lang.String[];
>>           n0 = null;
>>           b0 = 0;
>>
>>        label0:
>>           if b0 >= 5 goto label1;
>>
>>           $r2 = new Node;
>>           specialinvoke $r2.<Node: void <init>()>();
>>           r1 = $r2;
>>           r1.<Node: Node n> = n0;      // <-----------------------
>>           r3 = r1;
>>           i1 = b0 + 1;
>>           goto label0;
>>
>>        label1:
>>           return;
>>       }
>>
>> Notice that "t.n = x" has essentially turned to "t.n = null". This is
>> not some optimization as I have acquired this dump right after
>> the Jimple body creation phase. The optimized Jimple gets away with the
>> loop altogether which is even stranger.
>>
>> Oh, and it is not because I am not using the linked list later, which
>> makes it dead, or something like that.
>> This behaviour is observed even in larger programs where I am actively
>> using the list.
>>
>> This problem did not occur in the last build I used (Jan 26), but is
>> occurring in the current one.
>>
>> Regards,
>>
>> Rohan
>> _______________________________________________
>> Soot-list mailing list
>> Soot-list at sable.mcgill.ca
>> http://mailman.cs.mcgill.ca/mailman/listinfo/soot-list
>
>

-- 
Regards,
Rohan Padhye