This is not a bug - it's just the optimiser doing its job!

In Assembler, you get precisely one machine instruction for each Assembly statement; in a high-level language (eg, 'C') there is no such guarantee!!

Your 'C' source contains a repeated instruction sequnce:

   InSPack = 0;
   StartSPack = 0;
   return;

Rather than duplicate this code, the compiler has simply generated it once only, and placed a jump to it from the other instance!