javac - How to easily create Java bytecode dependent regression tests? -

i have identified bug in application (which processes bytecode using soot) arises on specific bytecode instructions.

i want create test specific case. however, i'm not able reliably write test code, compile expected bytecode, trigger bug.

this attempt trigger bug:

public void updaterhsonifeq() {         int x = 15;         int y = aircraftcontrol.readsensor(0);         // fixme != in bytecode instead of ==         if (x == y) {             aircraftcontrol.readsensor(y);         }         else {             aircraftcontrol.readsensor(x);         }     } 

the problem is, compiler changes branch logic inverting comparison , switching 2 branches. can see in bytecode below, != comparison instead of ==. however, bug i'm testing triggered ==.

 public void updaterhsonifeq();      0  bipush 15      2  istore_1 [x]      3  iconst_0      4  invokestatic aircraftcontrol.readsensor(int) : int [17]      7  istore_2 [y]      8  iload_1 [x]      9  iload_2 [y]     10  if_icmpne 21 <============================== should if_icmpeq     13  iload_2 [y]     14  invokestatic aircraftcontrol.readsensor(int) : int [17]     17  pop     18  goto 26     21  iload_1 [x]     22  invokestatic aircraftcontrol.readsensor(int) : int [17]     25  pop     26  return 

is there way write test cases need result in predictable bytecode easily? possible @ given there different java compilers, versions thereof etc?

if want specific bytecode instructions, obvious , reliable approach write directly in bytecode.

i've written open source assembler available here. simple cases, can jasmin, better documented. have disassembler, if need minor tweaks, can compile java class, disassemble, make tweak , reassemble.