incoherent stack height

["Uwe Dolinsky" <u.dolinsky@iname.com>]

Hi,

The method in question:

static void refer()
{
     for (int i=0;i<8;i++)
     {}
}

has the following baf output:

 push 0
 store.i i0
 load.i i0
 push 8
 ifcmpge.i return
 inc.i i0 1
 goto load.i i0
 return

When I insert a dup before the store and delete the subsequent load (which should
result in the same stack layout) I get:

   push 0
   dup1.i
   store.i i0
   push 8
   ifcmpge.i return
   inc.i i0 1
   goto push 8
   return

which I output right after the modification. Then soot complains:

Exception in thread "main" java.lang.RuntimeException: incoherent stack height a
t block merge point Block 1:
[preds: 0 2 ] [succs: 2 3 ]
push 8;
ifcmpge.i return;
Block 2:
[preds: 1 ] [succs: 1 ]
inc.i i0 1;
goto push 8;

computed blockHeight == 0 recorded blockHeight = 1
        at soot.baf.JasminClass.calculateStackHeight(JasminClass.java:1799)
        at soot.baf.JasminClass.calculateStackHeight(JasminClass.java:1804)

It compiles fine when I leave the original load instruction in the code together
with the newly inserted dup.

What am I doing wrong?
I'm using revision 1792.

Thanks
Uwe








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