Name: diC59631 Date: 05/21/98


Category general:jit_symantec ?

I have encountered the following problem when using JDK1.1.6 and the
included JIT compiler on Windows95.

The following simplified code runs fine:

public class JITError {
  public static void main(String argv[]) {
    getX();
  }
  private static void getX() {
    int x=0;
    while (x!=0) {
      try {
        Class.forName("");
      } catch (Exception ex) {
      }
      x--;
    }
  }
}
javap -c -private JITError
Method void getX()
   0 iconst_0
   1 istore_0
   2 goto 18
   5 ldc #1 <String "">
   7 invokestatic #7 <Method java.lang.Class forName(java.lang.String)>
  10 pop
  11 goto 15
  14 pop
  15 iinc 0 -1
  18 iload_0
  19 ifne 5
  22 return
Exception table:
   from to target type
     5 11 14 <Class java.lang.Exception>

------------------------------------------------------------------------
However with the following modification the JIT dll causes a windows error:
Now comment out the x-- line:


public class JITError {
  public static void main(String argv[]) {
    getX();
  }
  private static void getX() {
    int x=0;
    while (x!=0) {
      try {
        Class.forName("");
      } catch (Exception ex) {
      }
// x--;
    }
  }
}
javap -c -private JITError
Method void getX()
   0 iconst_0
   1 istore_0
   2 goto 18
   5 ldc #1 <String "">
   7 invokestatic #7 <Method java.lang.Class forName(java.lang.String)>
  10 pop
  11 goto 18
  14 pop
  15 goto 18
  18 iload_0
  19 ifne 5
  22 return
Exception table:
   from to target type
     5 11 14 <Class java.lang.Exception>

This causes the JIT Compiler error on windows 95:

JAVA caused an invalid page fault in
module SYMCJIT.DLL at 02cf:01f4704e.
Registers:
EAX=00000000 CS=02cf EIP=01f4704e EFLGS=00010293
EBX=01d90c24 SS=02d7 ESP=0063ed34 EBP=01d91b98
ECX=0063ee98 DS=02d7 ESI=01d9109c FS=0fdf
EDX=01d91a64 ES=02d7 EDI=01d9109c GS=0000
Bytes at CS:EIP:
39 70 04 74 04 8b d0 eb f5 8b 30 89 32 c7 00 00
Stack dump:
0063ee98 01f1091a 01d90c24 01d9109c 0063ee98 0063ee98 01d91f94 00000000 01d92688 0000005b 01d91c24 01f46f7e 01d91f94 0063ee98 01d91f84 0000005b


The only difference between the two sequencies of virtual code
is:

  14 pop
  15 iinc 0 -1
  18 iload_0

which is ok and

  14 pop
  15 goto 18
  18 iload_0

which fails. ie goto goes redundantly goes to the following command.
(Review ID: 30878)
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