Re: Make bfd.link_next field a union

[Alan Modra <amodra at gmail dot com>]

On Fri, Jun 13, 2014 at 09:33:25AM -0700, Michael Eager wrote:
> On 06/13/14 02:48, Alan Modra wrote:
> >This is the first of four patches aimed at fixing PR17047, a problem
> >that arose from people fussing over the linker not freeing the main
> >hash table before exit.  In hindsight, I probably should have just
> >reverted the original patch and HP's more recent fix..
> >
> >The link_next field of struct bfd is currently only used to chain
> >together linker input files.  This patch prepares to use the field to
> >stash the linker hash table, which is always created on the linker
> >output file.
> 
> Is there a reason not to create a link_hash field, rather than
> overload/reuse link_next?  I've never been fond of using unions
> to store unrelated data.

Memory is a finite resource.  I've never been fond of wasting it.  :)

In the case of struct bfd this isn't so important, where ld might only
have thousands of these structs in memory.  It becomes rather more
important in struct bfd_section, and critical in struct
bfd_link_hash_entry.  We even get complaints about the assembler using
too much memory,
eg. https://sourceware.org/bugzilla/show_bug.cgi?id=15930

-- 
Alan Modra
Australia Development Lab, IBM