Is there any way to get the bytecode offsets along with the line number ?

x = 0

Consider the above code snippet. The dis module outputs the line numbers along with the bytecode offsets.

  1           0 LOAD_CONST               0 (0)
              2 STORE_NAME               0 (x)
              4 LOAD_CONST               1 (None)
              6 RETURN_VALUE

Using the bytecode module I get the following, except the offset=<> part. Is there any way I can get these offsets, similar to the dis module’s output?

<LOAD_CONST arg=0 lineno=1 offset=0>
<STORE_NAME arg='x' lineno=1 offset=2>
<LOAD_CONST arg=None lineno=1 offset=4>
<RETURN_VALUE lineno=1 offset=6>>

I modified the bytecode module source to get the above output. If there is no other way except modifying the source, should I submit a PR?

[laike9m]

Thanks @MatthieuDartiailh for pointing me to this issue. I’m also interested in having a way to get offset easily, cause right now I have to iterate over Bytecode to calculate the offset, which is inefficient.

I read the above comments, from my understanding, the concern is mostly about whether it is appropriate to coupe [Concrete]Bytecode with the original bytecode. I don’t have enough understanding of the library to give a perfect answer, but perhaps we can consider a different approach.

So, we are concerned about having things coupled, how about create a separete class specifically for handling mapping, and leave [Concrete]Bytecode unchanged.

For example, a class called BytecodeMapper

mapper = BytecodeMapper(my_func.f_code)
bc: Bytecode = mapper.get_bytecode()
cbc: ConcreteBytecode = mapper.get_concrete_bytecode()

# For offset
mapper.find_instr_by_offset(int)  # returns a Instr
mapper.find_concrete_instr_by_offset(int)  # returns a ConcreteInstr
mapper.get_offset(Union[Instr, ConcreteInstr])

# For lineno
mapper.find_instrs_by_lineno(int)  # returns a list of Instr
mapper.find_concrete_instrs_by_lineno(int)  # returns a list of ConcreteInstr
mapper.get_lineno(Union[Instr, ConcreteInstr])

You can do whatever you want with the returned Bytecode object. When get_offset or get_lineno is called, it checks whether the passed in instr actually comes from this mapper(aka is, not ==). If not, just return None.

[laike9m]

@MatthieuDartiailh By “new offsets” you mean the offset after modifying Bytecode or ConcreteBytecode right? I would suggest not bother doing it, it feels hacky and may have problems? I can not say for other people, maybe someone need the offset to be updated as well, but I just don’t feel this to be a legitimate use.