RE: GCC 3.4.3 static constants, named sections, and -fkeep-static-consts

["Gary Funck" <gary at intrepid dot com>]

> From: James E Wilson
> Sent: Tuesday, March 08, 2005 6:59 PM
[...]
> 
> Try re-reading the docs.  -fkeep-static-consts is the default.  The 
> purpose of this is that we don't perform this optimization at -O0 
> normally, but if you use -fno-keep-static-consts, then we do.  So this 
> option can let you remove static consts in extra cases, but will never 
> prevent the compiler from removing them.

Jim,

Thanks for the follow-up. I filed a bug report,
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20319
and note #2 summarizes some relevant, conflicting facts:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20319#c2

The gist is the documentation describes the current behavior.
However, I don't think the current behavior is useful, and
it does not agree with comments in the source code, nor the
help line.

However, as you noted __attribute__ ((used)) works
well as a workaround, although it would be helpful if `used'
was added to the documentation as a supported attribute that
can be applied to variables.

I think that the switch name
-fkeep-static-consts might be more consistenly named if it
was given the opposite sense and named something like
-fdelete-unused-static-consts.  The idea here is that by
asserting the switch a particular optimization is _enabled_.
Thus the optimizations performed at each level can be consistently
enumerated by asserting a particular set of switches which enable
specific optimizations.  This would change the present user interface,
however, I doubt that anyone is making extensive use of the current
interface because at present only -fno-keep-static-consts, asserted
at -O0 (no optimization), actually changes the default behavior of
the compiler.