py/emitnative: Add support for archs that cannot read executable data.

In which case place the native function prelude in a bytes object, linked
from the const_table of that function.  An architecture should define
N_PRELUDE_AS_BYTES_OBJ to 1 before including py/emitnative.c to emit
correct machine code, then enable MICROPY_EMIT_NATIVE_PRELUDE_AS_BYTES_OBJ
so the runtime can correctly handle the prelude being in a bytes object.

1 files changed, 6 insertions, 0 deletions

diff --git a/py/objgenerator.c b/py/objgenerator.c
index 359dade88..2cfdb12f6 100644
--- a/py/objgenerator.c
+++ b/py/objgenerator.c
@@ -30,6 +30,7 @@
 
 #include "py/runtime.h"
 #include "py/bc.h"
+#include "py/objstr.h"
 #include "py/objgenerator.h"
 #include "py/objfun.h"
 #include "py/stackctrl.h"
@@ -88,6 +89,11 @@ STATIC mp_obj_t native_gen_wrap_call(mp_obj_t self_in, size_t n_args, size_t n_k
 
     // Determine start of prelude, and extract n_state from it
     uintptr_t prelude_offset = ((uintptr_t*)self_fun->bytecode)[0];
+    #if MICROPY_EMIT_NATIVE_PRELUDE_AS_BYTES_OBJ
+    // Prelude is in bytes object in const_table, at index prelude_offset
+    mp_obj_str_t *prelude_bytes = MP_OBJ_TO_PTR(self_fun->const_table[prelude_offset]);
+    prelude_offset = (const byte*)prelude_bytes->data - self_fun->bytecode;
+    #endif
     const uint8_t *ip = self_fun->bytecode + prelude_offset;
     size_t n_state, n_exc_stack_unused, scope_flags, n_pos_args, n_kwonly_args, n_def_args;
     MP_BC_PRELUDE_SIG_DECODE_INTO(ip, n_state, n_exc_stack_unused, scope_flags, n_pos_args, n_kwonly_args, n_def_args);