try to use the same str object for all code filenames when compiling or unmarshalling (#12190)

This should reduce memory usage.

1 files changed, 19 insertions, 0 deletions

diff --git a/Python/marshal.c b/Python/marshal.c
index f66b765..7b327ad 100644
--- a/Python/marshal.c
+++ b/Python/marshal.c
@@ -58,6 +58,7 @@ typedef struct {
     int depth;
     /* If fp == NULL, the following are valid: */
     PyObject *str;
+    PyObject *current_filename;
     char *ptr;
     char *end;
     int version;
@@ -976,6 +977,18 @@ r_object(RFILE *p)
             filename = r_object(p);
             if (filename == NULL)
                 goto code_error;
+            if (PyUnicode_CheckExact(filename)) {
+                if (p->current_filename != NULL) {
+                    if (!PyUnicode_Compare(filename, p->current_filename)) {
+                        Py_DECREF(filename);
+                        Py_INCREF(p->current_filename);
+                        filename = p->current_filename;
+                    }
+                }
+                else {
+                    p->current_filename = filename;
+                }
+            }
             name = r_object(p);
             if (name == NULL)
                 goto code_error;
@@ -1037,6 +1050,7 @@ PyMarshal_ReadShortFromFile(FILE *fp)
     RFILE rf;
     assert(fp);
     rf.fp = fp;
+    rf.current_filename = NULL;
     rf.end = rf.ptr = NULL;
     return r_short(&rf);
 }
@@ -1046,6 +1060,7 @@ PyMarshal_ReadLongFromFile(FILE *fp)
 {
     RFILE rf;
     rf.fp = fp;
+    rf.current_filename = NULL;
     rf.ptr = rf.end = NULL;
     return r_long(&rf);
 }
@@ -1106,6 +1121,7 @@ PyMarshal_ReadObjectFromFile(FILE *fp)
     RFILE rf;
     PyObject *result;
     rf.fp = fp;
+    rf.current_filename = NULL;
     rf.depth = 0;
     rf.ptr = rf.end = NULL;
     result = r_object(&rf);
@@ -1118,6 +1134,7 @@ PyMarshal_ReadObjectFromString(char *str, Py_ssize_t len)
     RFILE rf;
     PyObject *result;
     rf.fp = NULL;
+    rf.current_filename = NULL;
     rf.ptr = str;
     rf.end = str + len;
     rf.depth = 0;
@@ -1214,6 +1231,7 @@ marshal_load(PyObject *self, PyObject *f)
     if (data == NULL)
         return NULL;
     rf.fp = NULL;
+    rf.current_filename = NULL;
     if (PyBytes_Check(data)) {
         rf.ptr = PyBytes_AS_STRING(data);
         rf.end = rf.ptr + PyBytes_GET_SIZE(data);
@@ -1282,6 +1300,7 @@ marshal_loads(PyObject *self, PyObject *args)
     s = p.buf;
     n = p.len;
     rf.fp = NULL;
+    rf.current_filename = NULL;
     rf.ptr = s;
     rf.end = s + n;
     rf.depth = 0;