control printing from the garbage collector

General Form:
(gc-verbose arg)

Garbage collection (gc) is performed by every Lisp implementation; see gc$. However, different ACL2 builds might see more or fewer messages. This macro is intended to provide an interface for controlling the verbosity, which is off if the argument evaluates to nil and otherwise is on.

The above functionality is only supported for the following host Common Lisp implementations: CCL, CMUCL, and GCL. Otherwise, the only effect of this macro is to print a notice that it is not supported. You are welcome to contact the ACL2 developers if you would like to help in adding such support for another host Common Lisp.

Evaluation of a call of this macro always returns nil.