python · brandtbucher · May 19, 2025 · May 19, 2025 · May 19, 2025 · May 19, 2025
diff --git a/Include/internal/pycore_uop_ids.h b/Include/internal/pycore_uop_ids.h
diff --git a/Include/internal/pycore_uop_metadata.h b/Include/internal/pycore_uop_metadata.h
diff --git a/Lib/test/test_capi/test_opt.py b/Lib/test/test_capi/test_opt.py
@@ -1955,9 +1955,10 @@ def testfunc(n):
        self.assertEqual(res, TIER2_THRESHOLD)
        self.assertIsNotNone(ex)
        uops = get_opnames(ex)
-        self.assertIn("_CALL_ISINSTANCE", uops)
+        self.assertNotIn("_CALL_ISINSTANCE", uops)
        self.assertNotIn("_GUARD_THIRD_NULL", uops)
        self.assertNotIn("_GUARD_CALLABLE_ISINSTANCE", uops)
+        self.assertIn("_POP_CALL_TWO_LOAD_CONST_INLINE_BORROW", uops)

    def test_call_list_append(self):
        def testfunc(n):
@@ -1987,9 +1988,10 @@ def testfunc(n):
        self.assertEqual(res, TIER2_THRESHOLD)
        self.assertIsNotNone(ex)
        uops = get_opnames(ex)
-        self.assertIn("_CALL_ISINSTANCE", uops)
+        self.assertNotIn("_CALL_ISINSTANCE", uops)
        self.assertNotIn("_TO_BOOL_BOOL", uops)
        self.assertNotIn("_GUARD_IS_TRUE_POP", uops)
+        self.assertIn("_POP_CALL_TWO_LOAD_CONST_INLINE_BORROW", uops)

    def test_call_isinstance_is_false(self):
        def testfunc(n):
@@ -2004,9 +2006,10 @@ def testfunc(n):
        self.assertEqual(res, TIER2_THRESHOLD)
        self.assertIsNotNone(ex)
        uops = get_opnames(ex)
-        self.assertIn("_CALL_ISINSTANCE", uops)
+        self.assertNotIn("_CALL_ISINSTANCE", uops)
        self.assertNotIn("_TO_BOOL_BOOL", uops)
        self.assertNotIn("_GUARD_IS_FALSE_POP", uops)
+        self.assertIn("_POP_CALL_TWO_LOAD_CONST_INLINE_BORROW", uops)

    def test_call_isinstance_subclass(self):
        def testfunc(n):
@@ -2021,9 +2024,10 @@ def testfunc(n):
        self.assertEqual(res, TIER2_THRESHOLD)
        self.assertIsNotNone(ex)
        uops = get_opnames(ex)
-        self.assertIn("_CALL_ISINSTANCE", uops)
+        self.assertNotIn("_CALL_ISINSTANCE", uops)
        self.assertNotIn("_TO_BOOL_BOOL", uops)
        self.assertNotIn("_GUARD_IS_TRUE_POP", uops)
+        self.assertIn("_POP_CALL_TWO_LOAD_CONST_INLINE_BORROW", uops)

    def test_call_isinstance_unknown_object(self):
        def testfunc(n):

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-05-19-20-52-53.gh-issue-134268.HPKX1e.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-05-19-20-52-53.gh-issue-134268.HPKX1e.rst
@@ -0,0 +1,2 @@
+Add ``_POP_CALL_TWO_LOAD_CONST_INLINE_BORROW`` and use it to further
+optimize ``CALL_ISINSTANCE``.
@@ -5342,6 +5342,15 @@ dummy_func(
            value = PyStackRef_FromPyObjectImmortal(ptr);
        }

+        tier2 pure op(_POP_CALL_TWO_LOAD_CONST_INLINE_BORROW, (ptr/4, callable, null, pop1, pop2 -- value)) {
+            PyStackRef_CLOSE(pop2);
+            PyStackRef_CLOSE(pop1);
+            (void)null; // Silence compiler warnings about unused variables
+            DEAD(null);
+            PyStackRef_CLOSE(callable);
+            value = PyStackRef_FromPyObjectImmortal(ptr);
+        }
+
        tier2 op(_CHECK_FUNCTION, (func_version/2 -- )) {
            assert(PyStackRef_FunctionCheck(frame->f_funcobj));
            PyFunctionObject *func = (PyFunctionObject *)PyStackRef_AsPyObjectBorrow(frame->f_funcobj);

diff --git a/Python/executor_cases.c.h b/Python/executor_cases.c.h
@@ -550,6 +550,10 @@ dummy_func(void) {
        value = sym_new_const(ctx, ptr);
    }

+    op(_POP_CALL_TWO_LOAD_CONST_INLINE_BORROW, (ptr/4, unused, unused, unused, unused -- value)) {
+        value = sym_new_const(ctx, ptr);
+    }
+
    op(_COPY, (bottom, unused[oparg-1] -- bottom, unused[oparg-1], top)) {
        assert(oparg > 0);
        top = bottom;
@@ -901,12 +905,12 @@ dummy_func(void) {
            // known types, meaning we can deduce either True or False

            // The below check is equivalent to PyObject_TypeCheck(inst, cls)
+            PyObject *out = Py_False;
            if (inst_type == cls_o || PyType_IsSubtype(inst_type, cls_o)) {
-                sym_set_const(res, Py_True);
-            }
-            else {
-                sym_set_const(res, Py_False);
+                out = Py_True;
            }
+            sym_set_const(res, out);
+            REPLACE_OP(this_instr, _POP_CALL_TWO_LOAD_CONST_INLINE_BORROW, 0, (uintptr_t)out);
        }
    }


diff --git a/Python/optimizer_cases.c.h b/Python/optimizer_cases.c.h
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Add ``_POP_CALL_TWO_LOAD_CONST_INLINE_BORROW`` and use it to further
		optimize ``CALL_ISINSTANCE``.