Use array instead of conditional for BUILD_SLICE args

Author: markshannon

Include/internal/pycore_opcode_metadata.h

@@ -65,8 +65,7 @@ def check_function(self, func, expected):
 class StackEffectTests(unittest.TestCase):
     def test_stack_effect(self):
         self.assertEqual(stack_effect(dis.opmap['POP_TOP']), -1)
-        self.assertEqual(stack_effect(dis.opmap['BUILD_SLICE'], 0), -1)
-        self.assertEqual(stack_effect(dis.opmap['BUILD_SLICE'], 1), -1)
+        self.assertEqual(stack_effect(dis.opmap['BUILD_SLICE'], 2), -1)
         self.assertEqual(stack_effect(dis.opmap['BUILD_SLICE'], 3), -2)
         self.assertRaises(ValueError, stack_effect, 30000)
         # All defined opcodes

Include/internal/pycore_uop_metadata.h

@@ -4695,11 +4695,10 @@ dummy_func(
             LLTRACE_RESUME_FRAME();
         }
 
-        inst(BUILD_SLICE, (start, stop, step if (oparg == 3) -- slice)) {
-            PyObject *start_o = PyStackRef_AsPyObjectBorrow(start);
-            PyObject *stop_o = PyStackRef_AsPyObjectBorrow(stop);
-            PyObject *step_o = PyStackRef_AsPyObjectBorrow(step);
-
+        inst(BUILD_SLICE, (args[oparg] -- slice)) {
+            PyObject *start_o = PyStackRef_AsPyObjectBorrow(args[0]);
+            PyObject *stop_o = PyStackRef_AsPyObjectBorrow(args[1]);
+            PyObject *step_o = oparg == 3 ? PyStackRef_AsPyObjectBorrow(args[2]) : NULL;
             PyObject *slice_o = PySlice_New(start_o, stop_o, step_o);
             DECREF_INPUTS();
             ERROR_IF(slice_o == NULL, error);