LOAD_GLOBAL can only include one PUSH_NULL

sweeneyde · Nov 30, 2023 · 5b08f80 · 5b08f80
1 parent 4c9da4c
commit 5b08f80
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Showing 2 changed files with 24 additions and 1 deletion.
diff --git a/Lib/test/test_peepholer.py b/Lib/test/test_peepholer.py
@@ -1075,5 +1075,28 @@ def test_no_unsafe_static_swap(self):
         ]
         self.cfg_optimization_test(insts, insts, consts=list(range(3)), nlocals=1)
 
+    def test_only_one_push_null_per_load_global(self):
+        # When optimizing func()(), a second pass shouldn't
+        # let the LOAD_GLOBAL absorb another PUSH_NULL.
+        before = [
+            ('PUSH_NULL', 0, 1),
+            ('PUSH_NULL', 0, 1),
+            ('LOAD_GLOBAL', 0, 1),
+            ('CALL', 0, 1),
+            ('CALL', 0, 1),
+            ('RETURN_VALUE', 0, 1),
+        ]
+        after = [
+            ('PUSH_NULL', 0, 1),
+            ('LOAD_GLOBAL', 1, 1),
+            ('CALL', 0, 1),
+            ('CALL', 0, 1),
+            ('RETURN_VALUE', 0, 1),
+        ]
+        self.cfg_optimization_test(before, expected_insts=after, consts=[])
+        self.cfg_optimization_test(after, expected_insts=after, consts=[])
+
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/Python/flowgraph.c b/Python/flowgraph.c
@@ -1554,7 +1554,7 @@ optimize_basic_block(PyObject *const_cache, basicblock *bb, PyObject *consts)
             case KW_NAMES:
                 break;
             case PUSH_NULL:
-                if (nextop == LOAD_GLOBAL && (inst[1].i_opcode & 1) == 0) {
+                if (nextop == LOAD_GLOBAL && (inst[1].i_oparg & 1) == 0) {
                     INSTR_SET_OP0(inst, NOP);
                     inst[1].i_oparg |= 1;
                 }