py: Add new cstack API for stack checking, with limit margin macro.

Currently the stack limit margin is hard-coded in each port's call to
`mp_stack_set_limit()`, but on threaded ports it's fiddlier and can lead to
bugs (such as incorrect thread stack margin on esp32).

This commit provides a new API to initialise the C Stack in one function
call, with a config macro to set the margin.  Where possible the new call
is inlined to reduce code size in thread-free ports.

Intended replacement for `MP_TASK_STACK_LIMIT_MARGIN` on esp32.

The previous `stackctrl.h` API is still present and unmodified apart from a
deprecation comment.  However it's not available when the
`MICROPY_PREVIEW_VERSION_2` macro is set.

This work was funded through GitHub Sponsors.

Signed-off-by: Angus Gratton <angus@redyak.com.au>

1 files changed, 2 insertions, 2 deletions

diff --git a/py/obj.c b/py/obj.c
index e43451dadd..1606ad5209 100644
--- a/py/obj.c
+++ b/py/obj.c
@@ -34,7 +34,7 @@
 #include "py/objint.h"
 #include "py/objstr.h"
 #include "py/runtime.h"
-#include "py/stackctrl.h"
+#include "py/cstack.h"
 #include "py/stream.h" // for mp_obj_print
 
 // Allocates an object and also sets type, for mp_obj_malloc{,_var} macros.
@@ -117,7 +117,7 @@ const char *mp_obj_get_type_str(mp_const_obj_t o_in) {
 
 void mp_obj_print_helper(const mp_print_t *print, mp_obj_t o_in, mp_print_kind_t kind) {
     // There can be data structures nested too deep, or just recursive
-    MP_STACK_CHECK();
+    mp_cstack_check();
     #ifndef NDEBUG
     if (o_in == MP_OBJ_NULL) {
         mp_print_str(print, "(nil)");