Re: [I don't think it's off-topic at all] Linking speed for C++

[Geoff Keating <geoffk at geoffk dot org>]

Joe Buck <jbuck@synopsys.COM> writes:

> On Wed, May 09, 2001 at 11:39:04AM -0700, Joe Buck wrote:
> > > Clearly, if the pointer points to a global symbol that is defined
> > > externally, we we still need a relocation.  But it will be common to refer
> > > to a function whose definition comes from the same object file, or the
> > > same .so (meaning that relocations can be eliminated when building the
> > > shared library).
> > 
> > No, you misunderstand.  If the symbol is _visible_ externally, then a
> > dynamic relocation is required.  Even if the actual definition comes
> > from the current dso.  This is just the way ELF dynamic linking works.
> 
> It seems that this should be fixable by making the linker smarter.  After
> all, for the case of an offset to the same dso, what we have is a
> constant.  What will this required dynamic relocation do?

There's no way to know, for an externally visible symbol, at link
time, which dso it is in, even if there is a definition in the same
dso as it is used, because it could be overridden elsewhere.

-- 
- Geoffrey Keating <geoffk@geoffk.org>