[Soot-list] Why JSubExpr if Jimple does not have subexpression?

[Z]

Thank you for your reply.

But, another difference between the 2 versions seem to be more serious:

the 2nd generated jimple  does not even introduce temporary variables,
while the first one does it !
It seems to me that the 2nd one is not a real jimple.

Zell.

On Fri, Jul 6, 2012 at 1:19 PM, Patrick Lam <p.lam at ece.uwaterloo.ca> wrote:

> Subtraction from a constant is probably not the interesting thing.
> That's easy to convert back to a SubExpr if you want anyway. I'd bet
> that javac/Soot doen't convert subtractions from integer values to
> AddExprs.
>
> pat
>
> On 07/06/2012 03:29 AM, Eric Bodden wrote:
> > Hmmm, interesting. Maybe the compiler just compiles the code that way
> > (for whatever reason). I would be surprised if Soot actually did this
> > conversion. Anyway - does it hurt?
> >
> > Eric
> >
> > On 6 July 2012 07:32, Z<zell08v at orange.fr>  wrote:
> >> Thanks Eric.
> >>
> >> In the following, I show 2 different versions of jimple files generated
> >> within my Eclipse. They are output to the same sootOutput directory,
> with
> >> the same file name "tester.Snippet.Jimple" . But the 2nd one seems to
> >> transform each SubExpr "x-1" to AddExpr "x+ -1" . Am I doing something
> wrong
> >> here? Thank you for your help.
> >>
> >> Zell.
> >>
> >> ---------My original test4() method in tester.Snippet.java
> is------------
> >>      static void test4() {
> >>          int y;
> >>          y = 7;
> >>          y = y+1;
> >>          y= y-1;
> >>      }
> >>
> >> -------This  following one is generated by right-clicking the java
> source,
> >> then SOOT->process SOOT File->create Jimple ---------------
> >>      static void test4()
> >>      {
> >>          int y, temp$0, temp$1, temp$2, temp$3;
> >>
> >>          temp$0 = 7;
> >>          y = temp$0;
> >>          temp$1 = y;
> >>          temp$2 = temp$1 + 1;
> >>          y = temp$2;
> >>          temp$3 = y - 1;
> >>          y = temp$3;
> >>          return;
> >>      }
> >>
> >> ---------------This following  one is launched by this  main() in Java:
> >> " ...main(String[] args) {  args="-f J tester.Snippet".split(" "); ...
> >> soot.Main.main(args);}" -------------
> >>
> >>      static void test4()
> >>      {
> >>          byte b0;
> >>          int i1, i2;
> >>
> >>          b0 = 7;
> >>          i1 = b0 + 1;
> >>          i2 = i1 + -1;
> >>          return;
> >>
> >>      }
> >>
> >> On Wed, Jul 4, 2012 at 10:34 AM, Eric Bodden<eric.bodden at ec-spride.de>
> >> wrote:
> >>>
> >>>> Apparently, Jimple transforms all the expressions like "x = y - 7 "
> to "
> >>>> z =
> >>>> y +  (-7)",
> >>>
> >>> I don't think it does - at least not if you process bytecode.
> >>
> >>
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> >>
> >
> >
> >
>
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