From: Alan Modra <amodra@gmail.com>
To: Andrew Haley <aph@redhat.com>
Cc: Jakub Jelinek <jakub@redhat.com>,
"Hogan, D. (GE Power & Water)" <D.Hogan@ge.com>,
"libffi-discuss@sourceware.org" <libffi-discuss@sourceware.org>
Subject: Re: RFC: variadic closures in x86/x86_64
Date: Tue, 26 Nov 2013 14:27:00 -0000 [thread overview]
Message-ID: <20131126142723.GD9211@bubble.grove.modra.org> (raw)
In-Reply-To: <5293221D.4010505@redhat.com>
On Mon, Nov 25, 2013 at 10:10:37AM +0000, Andrew Haley wrote:
> Sure, but we don't need a new libffi interface to do that. We need
> only to set %rax. And we can just do that anyway; it doesn't hurt.
>
> I must be missing something.
The claim to fame looks to be the ability to call variadic functions
without describing the arguments via ffi_prep_cif_var at the point of
call. Instead you do so in the function consuming the args. I'm not
sure what that gains you..
The patch suffers from the same flaw as my first attempt at adding
variadic argument support for PowerPC64 ELFv2, namely that you cannot
add fields to ffi_cif without breaking ABI compatibility.
Applications linked against an older version of libffi.so will supply
the old ffi_cif to a new shared library..
Oh, and gcc still contains the first attempt since no one has yet
approved an import from libffi to cure the problem.
--
Alan Modra
Australia Development Lab, IBM
next prev parent reply other threads:[~2013-11-26 14:27 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-25 2:46 Hogan, D. (GE Power & Water)
2013-11-25 9:29 ` Andrew Haley
2013-11-25 9:37 ` Jakub Jelinek
2013-11-25 10:10 ` Andrew Haley
2013-11-26 14:27 ` Alan Modra [this message]
2013-12-04 8:03 ` Hogan, D. (GE Power & Water)
2013-12-04 11:05 ` Philip Ashmore
[not found] ` <F023C084BCC16446BDA5B664305741E8091E8B@ALPMBAPA05.e2k.ad.ge.com>
2013-12-05 13:03 ` Philip Ashmore
2013-12-04 12:21 ` Andrew Haley
2013-12-04 18:28 ` Hogan, D. (GE Power & Water)
2013-12-04 18:51 ` Andrew Haley
2013-12-05 0:47 ` Hogan, D. (GE Power & Water)
2013-12-05 8:33 ` Andrew Haley
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=20131126142723.GD9211@bubble.grove.modra.org \
--to=amodra@gmail.com \
--cc=D.Hogan@ge.com \
--cc=aph@redhat.com \
--cc=jakub@redhat.com \
--cc=libffi-discuss@sourceware.org \
/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).