[Soot-list] Unwanted optimization by soot?

[Dharmendra Singh]

I was trying to implement ball larus path profiling on the following java
program using soot.

1 package test1;

2 public class Main {

3     public static void main(String args[]) {

4         int x = args[0].length();

5         try {

6             int b = x / 0;

7             System.err.println("Here");

8             System.err.println(b);

9         } catch (ArithmeticException e1) {

10             if (x < 5)

11                 x++;

12             else

13                 x--;

14             System.err.println("Exception: e1");

15         } catch (Exception e5) {

16             x += 10;

17         } finally {

18             System.err.println("Finally");

19         }

20         System.err.println(x);

21         return;

22     }

23 }

There is java.lang.ArithmeticException divide by zero on line 6. When I run
the program without instrumentation through soot, the exception is thrown
at line 6 and "Here" of line 7 is not printed. But when I run the
instrumented code, than exception is thrown after line 7 ( print "Here" ).

javap -c output of uninstrumented class file

        3: invokevirtual #2 // Method java/lang/String.length:()I

       6: istore_1

       7: iload_1

       8: iconst_0

       9: idiv

      10: istore_2

      11: getstatic #3 // Field java/lang/System.err:Ljava/io/PrintStream;

      14: ldc #4 // String Here

      16: invokevirtual #5 // Method
java/io/PrintStream.println:(Ljava/lang/String;)V

division is at line 9 and print "Here" at 16

javap -c output of instrumented class file

      27: getstatic #47 // Field java/lang/System.err:Ljava/io/PrintStream;

      30: ldc #23 // String Here

      32: invokevirtual #17 // Method
java/io/PrintStream.println:(Ljava/lang/String;)V

      35: lload_3

      36: ldc2_w #52 // long 15l

      39: ladd

      40: ldc2_w #52 // long 15l

      43: ladd

      44: lstore_3

      45: getstatic #47 // Field java/lang/System.err:Ljava/io/PrintStream;

      48: iload_0

      49: iconst_0

      50: idiv

      51: invokevirtual #39 // Method java/io/PrintStream.println:(I)V

Here line 30 is print "Here" and line 50 is division. (Ignore the extra
adds, they are for BL path profiling.)

I'm not doing any rearrangement of instructions during Transformation. Why
is this happening?

#java version

java version "1.7.0_95"

OpenJDK Runtime Environment (IcedTea 2.6.4) (7u95-2.6.4-3)

OpenJDK 64-Bit Server VM (build 24.95-b01, mixed mode)

#javac

javac 1.7.0_95

#soot

soot-nightly-05082016
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