private @NotNull Map<PsiVariable, IntList> getWritesOffsets() {
        final Map<PsiVariable, IntList> writeOffsets = new HashMap<>();
        for (int i = flowStart; i < flowEnd; i++) {
          Instruction instruction = instructions.get(i);
          if (instruction instanceof WriteVariableInstruction) {
            final PsiVariable variable = ((WriteVariableInstruction)instruction).variable;
            if (variable instanceof PsiLocalVariable || variable instanceof PsiParameter) {
              IntList offsets = writeOffsets.get(variable);
              if (offsets == null) writeOffsets.put(variable, offsets = new IntArrayList());
              offsets.add(i);
            }
          }
        }
        LOG.debug("writeOffsets:", writeOffsets);
        return writeOffsets;
      }
private @NotNull Map<PsiVariable, IntList> getWritesOffsets()