-;;;; info classes, info types, and type numbers, part I: what's needed not only
-;;;; at compile time but also at run time
-
-;;;; Note: This section is a blast from the past, a little trip down memory
-;;;; lane to revisit the weird host/target interactions of the CMU CL build
-;;;; process. Because of the way that the cross-compiler and target compiler
-;;;; share stuff here, if you change anything in here, you'd be well-advised to
-;;;; nuke all your fasl files and restart compilation from the very beginning
-;;;; of the bootstrap process.
-
-;;; Why do we suppress the :COMPILE-TOPLEVEL situation here when we're running
-;;; the cross-compiler? The cross-compiler (which was built from these sources)
-;;; has its version of these data and functions defined in the same places we'd
-;;; be defining into. We're happy with its version, since it was compiled from
-;;; the same sources, so there's no point in overwriting its nice compiled
-;;; version of this stuff with our interpreted version. (And any time we're
-;;; *not* happy with its version, perhaps because we've been editing the
-;;; sources partway through bootstrapping, tch tch, overwriting its version
-;;; with our version would be unlikely to help, because that would make the
-;;; cross-compiler very confused.)
+;;;; info classes, info types, and type numbers, part I: what's needed
+;;;; not only at compile time but also at run time
+
+;;;; Note: This section is a blast from the past, a little trip down
+;;;; memory lane to revisit the weird host/target interactions of the
+;;;; CMU CL build process. Because of the way that the cross-compiler
+;;;; and target compiler share stuff here, if you change anything in
+;;;; here, you'd be well-advised to nuke all your fasl files and
+;;;; restart compilation from the very beginning of the bootstrap
+;;;; process.
+
+;;; At run time, we represent the type of info that we want by a small
+;;; non-negative integer.
+(eval-when (:compile-toplevel :load-toplevel :execute)
+ (def!constant type-number-bits 6))
+(deftype type-number () `(unsigned-byte ,type-number-bits))
+
+;;; Why do we suppress the :COMPILE-TOPLEVEL situation here when we're
+;;; running the cross-compiler? The cross-compiler (which was built
+;;; from these sources) has its version of these data and functions
+;;; defined in the same places we'd be defining into. We're happy with
+;;; its version, since it was compiled from the same sources, so
+;;; there's no point in overwriting its nice compiled version of this
+;;; stuff with our interpreted version. (And any time we're *not*
+;;; happy with its version, perhaps because we've been editing the
+;;; sources partway through bootstrapping, tch tch, overwriting its
+;;; version with our version would be unlikely to help, because that
+;;; would make the cross-compiler very confused.)