Pre-compute empty tuple singleton

python · mdboom · Mar 27, 2025 · Mar 20, 2025 · Mar 20, 2025 · Mar 20, 2025
commit 40ad9fca75c0a17df4fbe88f1ba5811d14692723
@@ -106,6 +106,9 @@ extern PyTypeObject _PyExc_MemoryError;
                 }, \
                 .tuple_empty = { \
                     .ob_base = _PyVarObject_HEAD_INIT(&PyTuple_Type, 0), \
+                    /* Using the hash constants in tupleobject.c
+                       _PyHASH_XXPRIME_5 + (_PyHASH_XXPRIME_5 ^ 3527539UL) */ \
+                    .ob_hash = 5740354900026072187, \
                 }, \
                 .hamt_bitmap_node_empty = { \
                     .ob_base = _PyVarObject_HEAD_INIT(&_PyHamt_BitmapNode_Type, 0), \

diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
@@ -321,11 +321,6 @@ tuple_hash(PyObject *op)
 {
     PyTupleObject *v = _PyTuple_CAST(op);
 
-    // For the empty singleton, we don't need to dereference the pointer
-    if (op == (PyObject *)&_Py_SINGLETON(tuple_empty)) {
-        return _PyHASH_XXPRIME_5 + (_PyHASH_XXPRIME_5 ^ 3527539UL);
-    }
-
     if (v->ob_hash != (Py_uhash_t)-1) {
         return v->ob_hash;
     }