Re: Plugins always enabled in GCC 4.8?

[Joern Rennecke <amylaar@spamcop.net>]

Quoting Basile Starynkevitch <basile@starynkevitch.net>:

> I also am in favor of having a software linked dynamically with shared
> libraries, for a very pragramtical reason: If a software has shared
> libraries, then modifying one such library in its implementation (not its
> interface) is very often easier for the developer, who can, thanks to the
> dynamic linking, test and use his improved shared library more easily and
> more quickly. In particular, if GCC were made of shared libraries, I believe
> that the build time would be much faster for the developer (ie the GCC
> contributor), and this is a big comfort in practice.

I don't see that.  Re-linking cc1 / cc1plus is reasonably fast.  And you'll
have to rebuild all the target libraries for a full test, no matter if
you have a monolithic exectuable or one with lots of dsos.  But in the
latter case, you'll have to dynamically link against numerous
dso for each library file compilation.

Where we could save rebuilding time is in cutting unwanted header
file dependencies, like tm.h included by frontends.
So, in that sense, more modularity helps build times.

But any gain from not statically re-linking the full executable is likely
already lost by more resource-hungry -fpic compilation, and even more
so by the dynamic link overhead.

Time savings when compiling the compiler with lto might be more noticable,
but only because you add additionaly boundaries which severely limit of
what lto can do for you.  lto and fast turn-around times don't mix very
well, anyway.