mpy-cross viper incompatibility with OBJ_REPR_B
Port, board and/or hardware
unix port, obj_repr_b, x86 (32-bit)
MicroPython version
based on v1.27.0-preview-154-g44986b1f04
Reproduction
- Make a 32-bit REPR_B "standard" or "coverage" build (from e.g., #17688)
- Run
RUN_TESTS_MPY_CROSS_FLAGS="--mpy-cross-flags=\"-march=x86 -msmall-int-bits=30\"" make -C ports/unix/ VARIANT=standard test_full_no_native# orVARIANT=coverage, depending
Expected behaviour
Tests pass
Observed behaviour
12 tests failed: micropython/native_gen.py micropython/native_misc.py micropython/native_try.py micropython/viper_import.py micropython/native_try_deep.py micropython/native_while.py micropython/native_with.py micropython/viper_misc3.py micropython/native_closure.py micropython/native_const.py micropython/native_for.py micropython/viper_with.py
I didn't dig deeply because native & viper were not important to my use case but I think that there are some assumptions about the encoding of small integer values as discussed in a related PR: https://github.com/micropython/micropython/pull/17688#issuecomment-3075383706
} else if (si->vtype == VTYPE_INT || si->vtype == VTYPE_UINT) {
ASM_MOV_REG_IMM(emit->as, reg_dest, (uintptr_t)MP_OBJ_NEW_SMALL_INT(si->data.u_imm));
Additional Information
No, I've provided everything above.
Code of Conduct
Yes, I agree
mpy-cross: Assertion failed for `-march=debug` and Viper code
Port, board and/or hardware
mpy-cross on Linux/amd64
MicroPython version
MicroPython v1.26.0-preview.196.g5f058e986 on 2025-06-09; linux [GCC 15.1.1] version
Reproduction
- Build
mpy-crosswithout any special flags or parameters (as in,make -C mpy-cross clean && make -C mpy-cross - Run
./mpy-cross/build/mpy-cross -march=debug ./tests/micropython/viper_ptr16_store.py
Expected behaviour
mpy-cross should not crash on exit but terminate gracefully.
Observed behaviour
mpy-cross will crash with:
mpy-cross: ../py/asmbase.c:56: mp_asm_base_start_pass: Assertion `as->code_base != NULL' failed.
after dumping native meta-opcodes to STDOUT.
Additional Information
This only happens for Viper code. For example, dumping tests/micropython/native_closure.py or tests/micropython/meminfo.py doesn't trigger the assertion.
I haven't really looked into this, but it seems like Viper code would still trigger an emit pass even for the debug arch? This could probably be fixed if N_DEBUG would be propagated into py/asmbase.c too but it doesn't seem to be the case.
Code of Conduct
Yes, I agree