[Soot-list] Re: Global variables in soot

[John Chaitanya Kati]

so if any one(one operand) them is a field ref, then that expression is 
available after that program point. but in soot, this is causing problem as they are being 
assigned to local variables.



On Wed, 2 May 2007, John Chaitanya Kati wrote:

> by expressions i mean those involving two operands like a*b, a+b etc...
>
>
> On Fri, 4 May 2007, Eric Bodden wrote:
>
>> So in your example, would it ot suffice to say that...
>> 
>> $i2 = <Test: int a>;
>> 
>> ... here the expression "<Test: int a>" is available in $i2?
>> 
>> So whenever a field reference is assigned to a local, it's expression
>> is available in that local.
>> 
>> Eric
>> 
>> On 04/05/07, John Chaitanya Kati <johnkati at cse.iitb.ac.in> wrote:
>>> Hi,
>>>     I am trying to implement inter-procedural available expression
>>> analysis using call string approach. As far as i know, i have to take care
>>> of expressions which have only one or both operands as global and create a
>>> bitvector of only those expressions. If both variables in the expression
>>> are local then i need not care for such type of expressions. But its
>>> getting difficult for me now...
>>> 
>>> 
>>> 
>>> 
>>> 
>>> On Fri, 4 May 2007, Eric Bodden wrote:
>>> 
>>> > Hi again.
>>> >
>>> > Sorry but I overlooked something. As Patrick just reminded me,
>>> > points-to analysis only works for reference types, while the field in
>>> > your example is an int. So it seems like you would have to write your
>>> > own analysis for this.
>>> >
>>> > What are you actually trying to achieve?
>>> >
>>> > Eric
>>> >
>>> > On 04/05/07, Eric Bodden <eric.bodden at mail.mcgill.ca> wrote:
>>> >> Ah, I see.
>>> >>
>>> >> In this case, I think you need points-to analysis. You want to find
>>> >> out which values $i2 could possibly point to. We have some tutorials
>>> >> and papers about how to use points-to analysis in Soot online.
>>> >>
>>> >> Eric
>>> >>
>>> >> On 04/05/07, John Chaitanya Kati <johnkati at cse.iitb.ac.in> wrote:
>>> >> > for my below program, jimple is giving the following output
>>> >> >         int i0, i1, $i2, $i3;
>>> >> >          $i2 = <Test: int a>;
>>> >> >          i1 = $i2 * i0;
>>> >> >
>>> >> > so its treating $i2 as local since its getting declared. But actually 
>>> it
>>> >> > represents variable 'a' which is global. I need this information for
>>> >> > interprocedural available expression analysis. So how do i resolve it 
>>> ?
>>> >> >
>>> >> >
>>> >> >
>>> >> >
>>> >> > On Fri, 4 May 2007, Eric Bodden wrote:
>>> >> >
>>> >> > > Ok, so what you mean by global variables are actually fields. it's 
>>> as
>>> >> > > I said: local variables are represented by soot.Local's and
>>> >> > > fields/global variables by soot.jimple.FieldRef's.
>>> >> > >
>>> >> > > Eric
>>> >> > >
>>> >> > > On 04/05/07, John Chaitanya Kati <johnkati at cse.iitb.ac.in> wrote:
>>> >> > >> By global variables i meant, which are available to all the 
>>> methods of
>>> >> the
>>> >> > >> class.
>>> >> > >> class Test
>>> >> > >> {       static public int a=5;
>>> >> > >>         static public void main(String args[])
>>> >> > >>         {
>>> >> > >>                 int b=10,c;
>>> >> > >>                 c = a*b;
>>> >> > >>                 add(a,b);
>>> >> > >>         }
>>> >> > >>         static void add(int i, int j)
>>> >> > >>         {
>>> >> > >>                 i=i+j;
>>> >> > >>                 a=15;
>>> >> > >>         }
>>> >> > >> }
>>> >> > >> a is global, b,c are local to main. I want to find out such 
>>> variables.
>>> >> > >>
>>> >> > >>
>>> >> > >>
>>> >> > >>
>>> >> > >>
>>> >> > >>
>>> >> > >>
>>> >> > >>
>>> >> > >>
>>> >> > >>
>>> >> > >>
>>> >> > >> On Fri, 4 May 2007, Eric Bodden wrote:
>>> >> > >>
>>> >> > >> > What's a global variable?
>>> >> > >> >
>>> >> > >> > Soot knows variables of type soot.Local. Those are obviously 
>>> local.
>>> >> > >> > Then there also are field references, which are obviously field
>>> >> > >> > references. Are those what you mean by global? (Of course, a 
>>> local
>>> >> can
>>> >> > >> > well be assigned a field reference, the same way as it can 
>>> happen in
>>> >> > >> > Java code.)
>>> >> > >> >
>>> >> > >> > Eric
>>> >> > >> >
>>> >> > >> > On 04/05/07, John Chaitanya Kati <johnkati at cse.iitb.ac.in> 
>>> wrote:
>>> >> > >> >> Hi,
>>> >> > >> >>    Is there a way to find out if a variable is global or not in
>>> >> soot ?
>>> >> > >> >>
>>> >> > >> >> --
>>> >> > >> >> Thanks for any help in advance
>>> >> > >> >> John Chaitanya
>>> >> > >> >>
>>> >> > >> >
>>> >> > >> >
>>> >> > >> >
>>> >> > >>
>>> >> > >> --
>>> >> > >>
>>> >> > >> Thanks
>>> >> > >> John Chaitanya
>>> >> > >> Like a rose trampled on the ground, you took the fall and thought 
>>> of
>>> >> me...
>>> >> > >>
>>> >> > >
>>> >> > >
>>> >> > >
>>> >> >
>>> >> > --
>>> >> >
>>> >> > Thanks
>>> >> > John Chaitanya
>>> >> > Like a rose trampled on the ground, you took the fall and thought of
>>> >> me...
>>> >> >
>>> >>
>>> >>
>>> >> --
>>> >> Eric Bodden
>>> >> Sable Research Group
>>> >> McGill University, Montréal, Canada
>>> >>
>>> >
>>> >
>>> >
>>> 
>>> --
>>> 
>>> Thanks
>>> John Chaitanya
>>> Like a rose trampled on the ground, you took the fall and thought of me...
>> 
>> 
>> 
>
>

-- 

Thanks
John Chaitanya
Like a rose trampled on the ground, you took the fall and thought of me...