@var{m} must be the machine mode for pointers on the machine in use.
The expression @var{y} must be one of three forms:
-@table @code
@code{(plus:@var{m} @var{x} @var{z})},
@code{(minus:@var{m} @var{x} @var{z})}, or
@code{(plus:@var{m} @var{x} @var{i})},
-@end table
where @var{z} is an index register and @var{i} is a constant.
Here is an example of its use: