[3.10] bpo-45355: More use of sizeof(_Py_CODEUNIT) (GH-28720). (GH-28721)

(cherry picked from commit 252b7bcb236dc261f3af1275bc90f9a303d9648f)
diff --git a/Objects/frameobject.c b/Objects/frameobject.c
index 8974d37..d02cf9d 100644
--- a/Objects/frameobject.c
+++ b/Objects/frameobject.c
@@ -275,8 +275,8 @@ marklines(PyCodeObject *code, int len)
     }
 
     while (PyLineTable_NextAddressRange(&bounds)) {
-        assert(bounds.ar_start/2 < len);
-        linestarts[bounds.ar_start/2] = bounds.ar_line;
+        assert(bounds.ar_start/(int)sizeof(_Py_CODEUNIT) < len);
+        linestarts[bounds.ar_start/sizeof(_Py_CODEUNIT)] = bounds.ar_line;
     }
     return linestarts;
 }
diff --git a/Python/compile.c b/Python/compile.c
index b007859..97aa224 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -6619,7 +6619,7 @@ static int
 assemble_line_range(struct assembler *a)
 {
     int ldelta, bdelta;
-    bdelta =  (a->a_offset - a->a_lineno_start) * 2;
+    bdelta =  (a->a_offset - a->a_lineno_start) * sizeof(_Py_CODEUNIT);
     if (bdelta == 0) {
         return 1;
     }