QUERY · ISSUE

Emitted code epilogue block contains a superflous jump to the next available code address.

openby agattiopened 2025-01-17updated 2025-01-17

bug

Port, board and/or hardware

mpy-cross built from git commit 6db29978ac8954f3686f9eb59dd71b55c3495456 (current master)

MicroPython version

MicroPython v1.25.0-preview.216.g6db29978a.dirty on 2025-01-17; mpy-cross emitting mpy v6.3

Reproduction

Run mpy-cross -X emit=native -march=debug tests/basics/0prelim.py
Look at the last part of the output for a jump to label_0.

This applies to any supported architecture with a native emitter, but -march=debug is used in the command line to make the problem visible without using a disassembler.

Expected behaviour

There should be no empty jump being emitted at the end of a block.

Observed behaviour

At the end of an emitted block of code this can be seen (taken from tests/basics/0prelim.py):

    ...
    jump(label_0)
label(label_0)
EXIT(0)

This applies also to functions that need a more involved cleanup procedure:

(tests/basics/async_for.py):

    ...
    jump(label_0)
    dead_code load(r_temp0, r_fun_table, 0)
    dead_code store(r_temp0, r_local2, 5)
    dead_code mov_reg_imm(r_temp0, 40=0x28)
    dead_code add(r_temp0, r_local2)
    dead_code store(r_temp0, r_local2, 2)
    dead_code mov_reg_imm(r_temp0, 0=0x0)
    dead_code mov_local_reg(local_3, r_temp0)
    dead_code jump(label_0)
label(label_0)
    call_ind(nlr_pop)
    mov_reg_local(r_ret, local_3)
EXIT(0)

(tests/basics/array_micropython.py):

    ...
    mov_local_reg(local_3, r_ret)
    jump(label_0)
label(label_0)
    mov_reg_local(r_arg1, local_6)
    call_ind(native_swap_globals)
    call_ind(nlr_pop)
    mov_reg_local(r_ret, local_3)
EXIT(0)

Additional Information

This is not specific to mpy-cross as the same issue occurs when emitting a block of code at runtime as well.

Code of Conduct

Yes, I agree

CANDIDATE · PULL REQUEST

py: fix native emitter to work with `async with` statements

mergedby dpgeorgeopened 2024-06-20updated 2024-08-11

py-core

This fixes the native emitter so that async with statements now work with it.

This PR also includes a new "debug native emitter" that can be used to print out pseudo instructions generated by the native emitter, to help debug issues with it. Eg with the following test.py file:

@micropython.native
def f():
    return 1

mpy-cross can be used as follows to get debug output from the native emitter:

$ ./build/mpy-cross -march=debug test.py
ENTRY(num_locals=6)
    load(r_fun_table, r_arg1, 1)
    load(r_local3, r_fun_table, 2)
    load(r_fun_table, r_fun_table, 3)
    load(r_fun_table, r_fun_table, 0)
    mov_local_reg(local_0, r_arg1)
    mov_reg_imm(r_arg1, 1=0x1)
    mov_local_reg(local_3, r_arg1)
    mov_reg_local_addr(r_arg1, local_0)
    call_ind(setup_code_state)
    mov_reg_imm(r_ret, 3=0x3)
    jump(label_0)
    dead_code load(r_ret, r_fun_table, 0)
    dead_code jump(label_0)
label(label_0)
EXIT(0)