Add missing unwind helper implementations

Objects/codeobject.c

@@ -1310,6 +1310,30 @@ PyCode_Addr2Line(PyCodeObject *co, int addrq)
     return _PyCode_CheckLineNumber(addrq, &bounds);
 }
 
+int
+_PyCode_SafeAddr2Line(PyCodeObject *co, int addrq)
+{
+    if (co == NULL) {
+        return -1;
+    }
+    /*
+     * dump_frame() may be called from signal handlers or other contexts where
+     * the code object could already be in the process of being torn down.
+     * Basic sanity checks help us avoid dereferencing obviously invalid
+     * objects while still providing a best-effort line number when possible.
+     */
+    if (!Py_IS_TYPE(co, &PyCode_Type)) {
+        return -1;
+    }
+    if (Py_REFCNT(co) <= 0) {
+        return -1;
+    }
+    if (addrq < 0 || addrq >= _PyCode_NBYTES(co)) {
+        return -1;
+    }
+    return PyCode_Addr2Line(co, addrq);
+}
+
 void
 _PyLineTable_InitAddressRange(const char *linetable, Py_ssize_t length, int firstlineno, PyCodeAddressRange *range)
 {

Python/ceval.c

@@ -52,6 +52,19 @@
 #include <stdlib.h>
 #include <stdbool.h>              // bool
 
+bool
+_PyEval_NoToolsForUnwind(PyThreadState *tstate)
+{
+    assert(tstate != NULL);
+    /*
+     * The generator fast-path in gen_close() only applies when we are sure
+     * that no tracing or profiling callbacks are going to observe the stack
+     * unwinding.  In that situation we can skip some of the normal unwinding
+     * machinery.
+     */
+    return !tstate->cframe->use_tracing;
+}
+
 /* ======================== Firmament2 source scope ======================== */
 #include <pythread.h>   /* Py_tss_t */
 #include <string.h>     /* strlen, memcpy */