[Soot-list] try catch transformation question

[Heejong Lee]

Hi, again.

Anybody explain why this happen?

original file:
  1 import java.io.*;
  2
  3 public class T {
  4     Exception returnExpt(int x) {
  5         if(x > 0) return new Exception();
  6         else return new IOException();
  7     }
  8     void test() {
  9         Exception e = returnExpt(1);
 10         String x = null;
 11         try {
 12             throw e;
 13         } catch(IOException i) {
 14             System.out.println("IOException");
 15             x.toUpperCase(); // no error
 16         } catch(Exception ex) {
 17             System.out.println("Exception");
 18             x.toUpperCase(); // error
 19         }
 20     }
 21     public static void main(String[] argv) {
 22         T t = new T();
 23         t.test();
 24     }
 25 }

jimple output(with -allow-phantom-refs -f jimple):
 34     void test()
 35     {
 36         T r0;
 37         java.lang.Exception r1, $r6, r7;
 38         null_type n0;
 39         java.io.IOException r2, $r3;
 40         java.io.PrintStream $r4, $r8;
 41
 42         r0 := @this: T;
 43         r1 = virtualinvoke r0.<T: java.lang.Exception returnExpt(int)>(1);
 44         n0 = null;
 45
 46      label0:
 47         throw r1;
 48
 49      label1:
 50         $r3 := @caughtexception;
 51         r2 = $r3;
 52         $r4 = <java.lang.System: java.io.PrintStream out>;
 53         virtualinvoke $r4.<java.io.PrintStream: void
println(java.lang.String)>("IOException");
 54         virtualinvoke n0.<java.lang.String: java.lang.String
toUpperCase()>();
 55         goto label2;
 56
 57      label2:
 58         return;
 59
 60         catch java.io.IOException from label0 to label1 with label1;
 61     }

Where is a trap for java.lang.Exception after transformation?

FYI, the bytecode is normal:
void test();
  Code:
   0:	aload_0
   1:	iconst_1
   2:	invokevirtual	#6; //Method returnExpt:(I)Ljava/lang/Exception;
   5:	astore_1
   6:	aconst_null
   7:	astore_2
   8:	aload_1
   9:	athrow
   10:	astore_3
   11:	getstatic	#7; //Field java/lang/System.out:Ljava/io/PrintStream;
   14:	ldc	#8; //String IOException
   16:	invokevirtual	#9; //Method
java/io/PrintStream.println:(Ljava/lang/String;)V
   19:	aload_2
   20:	invokevirtual	#10; //Method
java/lang/String.toUpperCase:()Ljava/lang/String;
   23:	pop
   24:	goto	41
   27:	astore_3
   28:	getstatic	#7; //Field java/lang/System.out:Ljava/io/PrintStream;
   31:	ldc	#11; //String Exception
   33:	invokevirtual	#9; //Method
java/io/PrintStream.println:(Ljava/lang/String;)V
   36:	aload_2
   37:	invokevirtual	#10; //Method
java/lang/String.toUpperCase:()Ljava/lang/String;
   40:	pop
   41:	return
  Exception table:
   from   to  target type
     8    10    10   Class java/io/IOException

     8    10    27   Class java/lang/Exception

Thanks in advance!

--
Heejong Lee

Associate Research Engineer
Program Analysis Division
Fasoo.com, Inc. (www.spa-arrow.com)