[Soot-list] Re: A possible bug of Jimple generation in Soot

[Lin Li]

Hi Ondrej,

I think using Bugzilla is a good idea.

Lin

> Hi Bin,
>
> Thanks for the detailed report.
>
> It is a known limitation of the use-original-names option that it
> generates code that is not exactly like Jimple. In particular, it
> does not always have the property that values have been split along
> DU-UD webs, as in Jimple. Therefore, this option may make analyses,
> including alias analysis, less precise. This is the main reason why
> this option is not on by default.
>
> In some cases, it is not possible to split along DU-UD webs and keep the
> original names, because the original assignment of names to values is
> not along DU-UD webs. However, in this case, the relevant local is
> a stack local, so it seems it shouldn't have a name, so I don't see why
> Soot does not split it.
>
> I've cc'ed this message to the Soot mailing list. Perhaps someone there
> knows more about the use-original-names option and can explain this.
>
> The place to report problems such as this is the
> Soot mailing list. Note that you must be subscribed to the list in order
> to post to it. You can subscribe to the list at:
> http://www.sable.mcgill.ca/mailman/listinfo/soot-list
>
> In general, we are no longer using the bug tracker because of system
> administration issues. To the Soot people reading this: we do now
> have a Bugzilla set up at https://svn.sable.mcgill.ca/bugzilla, which
> should solve the issues with the old system. Should we start using and
> advertising it?
>
> Ondrej
>
> On Mon, Nov 15, 2004 at 10:23:05PM -0500, Bin Zhao wrote:
>>    Hi Ondrej,
>>
>>        I am Bin Zhao, a first-year graduate student in Computer Science
>>    Department in University of Maryland. Currently I am using Soot 2.1.0
>> to
>>    perform alias analysis for my course project. However, I found there
>> could
>>    be possibly a bug in the generated Jimple and caused an incorrect
>> analysis
>>    of alias. I tried to report the bug via the "Soot Bug Tracking" link
>> on
>>    the Soot Homepage. However the link didn't work any longer. I have
>> read
>>    your master thesis and know you are the author of Spark. Therefore I
>> am
>>    sending this email to you and you can forward to the appropriate
>> person.
>>
>>        The simple Java program is as the following:
>>
>>    import java.util.*;
>>
>>    public class ExampleA{
>>
>>      public static void main(String[] args){
>>        List l1 = new ArrayList();
>>        List l2 = new LinkedList();
>>        l2 = new ArrayList();
>>      }
>>    }
>>
>>        We set the use-original-names to true and the generated jimple
>> file is
>>    as the following;
>>
>>    public class ExampleA extends java.lang.Object
>>    {
>>
>>        public void <init>()
>>        {
>>            ExampleA l0;
>>
>>            l0 := @this: ExampleA;
>>            specialinvoke l0.<java.lang.Object: void <init>()>();
>>            return;
>>        }
>>
>>        public static void main(java.lang.String[])
>>        {
>>            java.lang.String[] l0;
>>            java.util.ArrayList $r0, l1, l2;
>>            java.util.LinkedList l2, $r2;
>>
>>            l0 := @parameter0: java.lang.String[];
>>            $r0 = new java.util.ArrayList;
>>            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>            specialinvoke $r0.<java.util.ArrayList: void <init>()>();
>>            l1 = $r0;
>>            ^^^^^^^^^
>>            $r2 = new java.util.LinkedList;
>>            specialinvoke $r2.<java.util.LinkedList: void <init>()>();
>>            l2 = $r2;
>>            $r0 = new java.util.ArrayList;
>>            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>            specialinvoke $r0.<java.util.ArrayList: void <init>()>();
>>            l2 = $r0;
>>            ^^^^^^^^^^
>>            return;
>>        }
>>    }
>>        You can notice that the generated jimple file uses the same stack
>>    variable $r0 for both the ArrayList allocations for l1 and l2. And
>> $r0 is
>>    assigned to both l1 and l2. When we perform alias analysis, it says
>> that
>>    after "l2 = new ArrayList()", l1 and l2 has non-empty intersection of
>>    points-to set.
>>
>>    thanks,
>>    Bin
>
>
>
>
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