marshalにTYPE_SMALL_REFを追加してみる

commit 4cef1f77f0731ef5f144ddf6ebf17e495303f1fd
Author: Inada Naoki <songofacandy@gmail.com>
Date:   2023-04-06 17:20:36 +0900

    exp: marshalにsmall refを作ってpycのサイズを観察する

diff --git a/Python/marshal.c b/Python/marshal.c
index 2966139cec..156e1bf3af 100644
--- a/Python/marshal.c
+++ b/Python/marshal.c
@@ -59,6 +59,7 @@ module marshal
 #define TYPE_STRING             's'
 #define TYPE_INTERNED           't'
 #define TYPE_REF                'r'
+#define TYPE_SMALL_REF          'R'
 #define TYPE_TUPLE              '('
 #define TYPE_LIST               '['
 #define TYPE_DICT               '{'
@@ -316,8 +317,15 @@ w_ref(PyObject *v, char *flag, WFILE *p)
         w = (int)(uintptr_t)entry->value;
         /* we don't store "long" indices in the dict */
         assert(0 <= w && w <= 0x7fffffff);
-        w_byte(TYPE_REF, p);
-        w_long(w, p);
+        if (w < 256) {
+        //if (false) {
+            w_byte(TYPE_SMALL_REF, p);
+            w_byte((unsigned char)w, p);
+        }
+        else {
+            w_byte(TYPE_REF, p);
+            w_long(w, p);
+        }
         return 1;
     } else {
         size_t s = p->hashtable->nentries;
@@ -1464,8 +1472,12 @@ r_object(RFILE *p)
         retval = v;
         break;
 
+    case TYPE_SMALL_REF:
+        n = (unsigned char) r_byte(p);
+        goto _read_ref;
     case TYPE_REF:
         n = r_long(p);
+    _read_ref:
         if (n < 0 || n >= PyList_GET_SIZE(p->refs)) {
             if (n == -1 && PyErr_Occurred())
                 break;
diff --git a/Tools/build/umarshal.py b/Tools/build/umarshal.py
index f61570cbaf..82f442fa02 100644
--- a/Tools/build/umarshal.py
+++ b/Tools/build/umarshal.py
@@ -23,6 +23,7 @@ class Type:
     STRING              = ord('s')
     INTERNED            = ord('t')
     REF                 = ord('r')
+    SMALL_REF           = ord('R')
     TUPLE               = ord('(')
     LIST                = ord('[')
     DICT                = ord('{')
@@ -296,6 +297,11 @@ def R_REF(obj: Any) -> Any:
             retval = self.refs[n]
             assert retval is not None
             return retval
+        elif type == Type.SMALL_REF:
+            n = self.r_byte()
+            retval = self.refs[n]
+            assert retval is not None
+            return retval
         else:
             breakpoint()
             raise AssertionError(f"Unknown type {type} {chr(type)!r}")