Issue #28126: Replace Py_MEMCPY with memcpy(). Visual Studio can properly optimize memcpy().
diff --git a/Python/marshal.c b/Python/marshal.c
index 627a842..87a4b24 100644
--- a/Python/marshal.c
+++ b/Python/marshal.c
@@ -130,7 +130,7 @@
     m = p->end - p->ptr;
     if (p->fp != NULL) {
         if (n <= m) {
-            Py_MEMCPY(p->ptr, s, n);
+            memcpy(p->ptr, s, n);
             p->ptr += n;
         }
         else {
@@ -140,7 +140,7 @@
     }
     else {
         if (n <= m || w_reserve(p, n - m)) {
-            Py_MEMCPY(p->ptr, s, n);
+            memcpy(p->ptr, s, n);
             p->ptr += n;
         }
     }