py/emitndebug: Add native debug emitter.

This emitter prints out pseudo-machine instructions, instead of the usual
output of the native emitter.  It can be enabled on any port via
`MICROPY_EMIT_NATIVE_DEBUG` (make sure other native emitters are disabled)
but the easiest way to use it is with mpy-cross:

    $ mpy-cross -march=debug file.py

Signed-off-by: Damien George <damien@micropython.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/py/asmbase.c b/py/asmbase.c
index cf64e3f3d..3fce543a7 100644
--- a/py/asmbase.c
+++ b/py/asmbase.c
@@ -30,6 +30,7 @@
 #include "py/obj.h"
 #include "py/misc.h"
 #include "py/asmbase.h"
+#include "py/persistentcode.h"
 
 #if MICROPY_EMIT_MACHINE_CODE
 
@@ -91,6 +92,11 @@ void mp_asm_base_label_assign(mp_asm_base_t *as, size_t label) {
     } else {
         // ensure label offset has not changed from PASS_COMPUTE to PASS_EMIT
         assert(as->label_offsets[label] == as->code_offset);
+        #if MICROPY_DYNAMIC_COMPILER && MICROPY_EMIT_NATIVE_DEBUG
+        if (mp_dynamic_compiler.native_arch == MP_NATIVE_ARCH_DEBUG) {
+            mp_printf(MICROPY_EMIT_NATIVE_DEBUG_PRINTER, "label(label_%u)\n", (unsigned int)label);
+        }
+        #endif
     }
 }