[gentoo-dev] Re: debug/release builds extensions/clarification proposal

Maciej Mrozowski <reavertm@××××××.fm> writes:

> - USE=debug is useless  when CFLAGS/LDFLAGS or FEATURES are not appropriate

What are you saying here? I'm afraid you're mistaken here.

For the most part, USE=debug means "enable debug code paths", which for
lots of projects simply means "enable assertions"; there are packages
that take this as "enable debug symbols too" but I don't think that's
very valid since users might want debug code paths but not symbols and
vice-versa (I indeed have debug symbols bug no debug codepaths enabled).

Now just to make sure the common misconceptions don't hit again:

- -ggdb *does not have any runtime performance hit*; neither in
   execution time nor in memory usage; the debug sections are not mapped
   into memory at all; this is true for both non-stripped and split
   executables;
- -O0 is not always a good idea; beside bugs in packages concealed by
   -O1+ [1], there are some further points: missing registers on x86
   causes build failures, and if ( 0 ) cases are not optimised away,
   resulting in stuff like FFmpeg not to link properly since undefined
   references are not pruned away; this means that using -O0
   unconditionally for any package for debug is not really an option;

[1] http://blog.flameeyes.eu/2008/09/02/testing-the-corner-cases

-- 
Diego "Flameeyes" Pettenò
http://blog.flameeyes.eu/