References: CLtL p. 160
Edit History: V1 9 Sep 1988, David Gray (initial version)
V2 19 Sep 1988, David Gray (delete first alternative)
The OPTIMIZE declaration provides a way to tell the compiler how important
various qualities are in order to guide which optimizations are done.
There is another quality, however, that is not mentioned, but is an
important consideration for the compiler: how much information
should be included in the object code to facilitate debugging. This
includes both annotation added to enable a debugger to display more
information to the user, and also suppression of optimizations that would
confuse debugging by making it harder to connect the object code with the
In the description of the OPTIMIZE declaration, add an additional quality
named DEBUG, described as "ease of debugging".
Since ease of debugging is an issue that the user will be concerned with,
and is an issue that the compiler needs to consider, this provides a clear
way for the user to control the amount of debugging information placed in
the object module, with DEBUG=0 meaning none and DEBUG=3 meaning "as much
No current implementation of this is known.
Cost to implementors:
All would have to update their handling of OPTIMIZE declarations to accept
the new quality.
Cost to users:
One more little feature to learn. Some problems may result from the
addition of the symbol DEBUG to the LISP package.
Provides users a standard way to control the interaction between
the compiler and debugger, and saves implementors from having to invent
Costs of Non-Adoption:
Continued confusion about how debug information should be controlled.
Concern has been raised that there is already a problem with the
non-orthogonality of SPEED, SAFETY, and SPACE that would be made even
worse with DEBUG added, since users tend to be perplexed by the
interactions of these qualities.