From: Paolo Bonzini <pbonzini@redhat.com>
To: "Eric Blake" <eblake@redhat.com>,
"Marc-André Lureau" <marcandre.lureau@redhat.com>
Cc: qemu-devel <qemu-devel@nongnu.org>,
"P. Berrange, Daniel" <berrange@redhat.com>,
"Armbruster, Markus" <armbru@redhat.com>
Subject: Re: [Qemu-devel] [PATCH 2/3] qobject: assume base of a qobject is at offset 0
Date: Wed, 21 Mar 2018 16:34:53 +0100 [thread overview]
Message-ID: <d91d87e4-e3f0-c21f-669a-d3e70258a949@redhat.com> (raw)
In-Reply-To: <26a3cea8-20ff-34a3-945b-044a730812b6@redhat.com>
On 21/03/2018 16:29, Eric Blake wrote:
>
> Not necessarily - can we use multiple layers of macros? (Untested)
>
> #define QOBJECT_0(x) x
> #define QOBJECT_1(x) ({ \
> QEMU_BUILD_BUG_ON(offsetof(typeof(*x), base)); \
> &(x)->base; })
> #define QOBJECT(x) QOBJECT_ ## QEMU_GENERIC(x, \
> (QObject *, 0),
> (const QObject *, 0),
> 1)(x)
>
> or with an additional layer of glue() if needed
>
> That is, reduce the QEMU_GENERIC expansion into something that generates
> only a single preprocessor token, where we then use to decide which
> OTHER macro to expand, so that we are only evaluating &(x)->base when we
> selected the derived types.
I don't think so. Macro expansion happens way earlier.
Paolo
next prev parent reply other threads:[~2018-03-21 15:35 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-21 13:40 [Qemu-devel] [PATCH 0/3] RFC: simplify qobject refcount Marc-André Lureau
2018-03-21 13:40 ` [Qemu-devel] [PATCH 1/3] compiler: extend QEMU_GENERIC to handle more arguments Marc-André Lureau
2018-03-21 13:40 ` [Qemu-devel] [PATCH 2/3] qobject: assume base of a qobject is at offset 0 Marc-André Lureau
2018-03-21 14:01 ` Paolo Bonzini
2018-03-21 14:08 ` Marc-André Lureau
2018-03-21 14:19 ` Eric Blake
2018-03-21 14:21 ` Marc-André Lureau
2018-03-21 14:49 ` Paolo Bonzini
2018-03-21 15:29 ` Eric Blake
2018-03-21 15:34 ` Paolo Bonzini [this message]
2018-03-21 15:55 ` Marc-André Lureau
2018-03-21 16:00 ` Paolo Bonzini
2018-03-21 16:11 ` Marc-André Lureau
2018-03-21 16:23 ` Paolo Bonzini
2018-03-21 16:59 ` Marc-André Lureau
2018-03-21 17:08 ` Eric Blake
2018-03-21 17:23 ` Marc-André Lureau
2018-03-21 17:38 ` Eric Blake
2018-03-21 17:43 ` Paolo Bonzini
2018-03-21 14:01 ` Eric Blake
2018-03-21 14:02 ` Paolo Bonzini
2018-03-21 13:40 ` [Qemu-devel] [PATCH 3/3] qobject: replace qobject_incref/QINCREF qobject_decref/QDECREF Marc-André Lureau
2018-03-21 14:28 ` Eric Blake
2018-03-21 14:51 ` Marc-André Lureau
2018-03-21 15:36 ` Eric Blake
2018-03-21 14:09 ` [Qemu-devel] [PATCH 0/3] RFC: simplify qobject refcount Eric Blake
2018-03-21 14:19 ` Marc-André Lureau
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