stackeffect(int opcode, int oparg)
{
	switch (opcode) {
		case POP_TOP:
			return -1;
		case ROT_TWO:
		case ROT_THREE:
		case ROT_FOUR:
			return 0;
		case DUP_TOP:
			return 1;

		case UNARY_POSITIVE:
		case UNARY_NEGATIVE:
		case UNARY_NOT:
		case UNARY_CONVERT:
		case UNARY_INVERT:
			return 0;

		case BINARY_POWER:
		case BINARY_MULTIPLY:
		case BINARY_DIVIDE:
		case BINARY_MODULO:
		case BINARY_ADD:
		case BINARY_SUBTRACT:
		case BINARY_SUBSCR:
		case BINARY_FLOOR_DIVIDE:
		case BINARY_TRUE_DIVIDE:
		case BINARY_LSHIFT:
		case BINARY_RSHIFT:
		case BINARY_AND:
		case BINARY_XOR:
		case BINARY_OR:
			return -1;

		case SLICE+0:
			return 0;
		case SLICE+1:
			return -1;
		case SLICE+2:
			return -1;
		case SLICE+3:
			return -2;

		case STORE_SLICE+0:
			return -2;
		case STORE_SLICE+1:
			return -3;
		case STORE_SLICE+2:
			return -3;
		case STORE_SLICE+3:
			return -4;

		case DELETE_SLICE+0:
			return -1;
		case DELETE_SLICE+1:
			return -2;
		case DELETE_SLICE+2:
			return -2;
		case DELETE_SLICE+3:
			return -3;

		case INPLACE_ADD:
		case INPLACE_SUBTRACT:
		case INPLACE_MULTIPLY:
		case INPLACE_DIVIDE:
		case INPLACE_MODULO:
			return -2;

		case STORE_SUBSCR:
			return -3;
		case DELETE_SUBSCR:
			return -2;

		case PRINT_EXPR:
			return -1;
		case PRINT_ITEM_TO:
			return -2;
		case PRINT_ITEM:
			return -1;
		case RETURN_VALUE:
			return -1;
		case YIELD_VALUE:
			return -1;
		case EXEC_STMT:
			return -3;
		case BUILD_CLASS:
			return -2;
		case STORE_NAME:
			return -1;
		case STORE_ATTR:
			return -2;
		case DELETE_ATTR:
			return -1;
		case STORE_GLOBAL:
			return -1;
		case BUILD_MAP:
			return 1;
		case COMPARE_OP:
			return -1;
		case STORE_FAST:
			return -1;
		case IMPORT_STAR:
			return -1;
		case IMPORT_NAME:
			return 0;
		case IMPORT_FROM:
			return 1;
		case LOAD_ATTR:
			return 0;
		case SETUP_EXCEPT:
			return 3;
		case SETUP_FINALLY:
			return 3;
		case FOR_ITER:
			return 1;
		case LOAD_LOCALS:
		case LOAD_CONST:
		case LOAD_NAME:
		case LOAD_ATTR:
		case LOAD_GLOBAL:
		case LOAD_FAST:
		case LOAD_CLOSURE:
		case LOAD_DEREF:
			return 1;
		case MAKE_CLOSURE: /* XXX depends on number of freevars */
			return -oparg;
		case MAKE_FUNCTION:
			return -oparg;
	}
}