Use low bit of LOAD_GLOBAL's oparg to indicate whether it should push an additional NULL. (GH-31933)

1 files changed, 13 insertions, 2 deletions

diff --git a/Python/compile.c b/Python/compile.c
index ac9ddbc..950c44a 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -1000,7 +1000,7 @@ stack_effect(int opcode, int oparg, int jump)
             return -1;
 
         case LOAD_GLOBAL:
-            return 1;
+            return (oparg & 1) + 1;
 
         /* Exception handling pseudo-instructions */
         case SETUP_FINALLY:
@@ -4185,8 +4185,12 @@ compiler_nameop(struct compiler *c, identifier name, expr_context_ty ctx)
     assert(op);
     arg = compiler_add_o(dict, mangled);
     Py_DECREF(mangled);
-    if (arg < 0)
+    if (arg < 0) {
         return 0;
+    }
+    if (op == LOAD_GLOBAL) {
+        arg <<= 1;
+    }
     return compiler_addop_i(c, op, arg);
 }
 
@@ -8812,6 +8816,13 @@ optimize_basic_block(struct compiler *c, basicblock *bb, PyObject *consts)
                 break;
             case KW_NAMES:
                 break;
+            case PUSH_NULL:
+                if (nextop == LOAD_GLOBAL && (inst[1].i_opcode & 1) == 0) {
+                    inst->i_opcode = NOP;
+                    inst->i_oparg = 0;
+                    inst[1].i_oparg |= 1;
+                }
+                break;
             default:
                 /* All HAS_CONST opcodes should be handled with LOAD_CONST */
                 assert (!HAS_CONST(inst->i_opcode));