From: Michael Matz <matz@suse.de>
To: Frederick Virchanza Gotham <cauldwell.thomas@gmail.com>
Cc: binutils@sourceware.org
Subject: Re: Linker : Make a map of typeinfo to vtable
Date: Mon, 22 Jan 2024 17:50:33 +0100 (CET) [thread overview]
Message-ID: <51e942dd-dbe0-f644-e9bb-0e12fc69f076@suse.de> (raw)
In-Reply-To: <CALtZhhMUxmUzWrHLB8xDA_0z0yjgZDLp8DqaofJvVk6rZznQ=g@mail.gmail.com>
Hello,
On Fri, 19 Jan 2024, Frederick Virchanza Gotham wrote:
> So I want to edit the source code for the GNU linker in order to add two
> new symbols to every binary:
>
> (1) __map_typeinfohash_vtable
> (2) __map_typeinfohash_vtable_size
>
> The first one is an array mapping the hashes of type_info's to vtable
> pointers. The second one is the number of elements in the array. The array
> would look something like the following in C++:
>
> pair<size_t, void const*> const g_vtables[] = {
> { typeid(MyClass).hash_code(), &_ZTI7MyClass },
> { typeid(YourClass).hash_code(), &_ZTI9YourClass },
> };
When you want to get from typeinfo to vtable pointer, why not just add
that pointer directly into the typeinfo? A hashtable is quite a
roundabout way to implement 'typeid(Type).vtable()' .
As you're proposing your general idea on a mailing list for new features
of C++, that seems like a more sensible design than hacking the linker.
Ciao,
Michael.
next prev parent reply other threads:[~2024-01-22 16:50 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-19 22:29 Frederick Virchanza Gotham
2024-01-19 22:52 ` Frederick Virchanza Gotham
2024-01-20 19:44 ` Frederick Virchanza Gotham
2024-01-21 3:27 ` Frederick Virchanza Gotham
2024-01-21 22:35 ` Frederick Virchanza Gotham
2024-01-22 16:50 ` Michael Matz [this message]
2024-01-25 10:17 ` Frederick Virchanza Gotham
2024-01-25 23:02 ` Frederick Virchanza Gotham
2024-01-27 10:56 ` Frederick Virchanza Gotham
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=51e942dd-dbe0-f644-e9bb-0e12fc69f076@suse.de \
--to=matz@suse.de \
--cc=binutils@sourceware.org \
--cc=cauldwell.thomas@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).