From: Segher Boessenkool <segher@kernel.crashing.org>
To: Joel Stanley <joel@jms.id.au>
Cc: linux-fbdev@vger.kernel.org, kvm@vger.kernel.org,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
dri-devel@lists.freedesktop.org,
Paul Mackerras <paulus@samba.org>,
alsa-devel@alsa-project.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 2/5] powerpc: Replace _ALIGN_DOWN() by ALIGN_DOWN()
Date: Tue, 21 Apr 2020 10:55:16 -0500 [thread overview]
Message-ID: <20200421155516.GT26902@gate.crashing.org> (raw)
In-Reply-To: <CACPK8XfqnqgkXcBzp=nqd=AJX1MK05eTNiyOdaEuRu3_6RsXSQ@mail.gmail.com>
Hi!
On Tue, Apr 21, 2020 at 01:04:05AM +0000, Joel Stanley wrote:
> On Mon, 20 Apr 2020 at 18:38, Christophe Leroy <christophe.leroy@c-s.fr> wrote:
> > _ALIGN_DOWN() is specific to powerpc
> > ALIGN_DOWN() is generic and does the same
> >
> > Replace _ALIGN_DOWN() by ALIGN_DOWN()
>
> This one is a bit less obvious. It becomes (leaving the typeof's alone
> for clarity):
>
> -((addr)&(~((typeof(addr))(size)-1)))
> +((((addr) - ((size) - 1)) + ((typeof(addr))(size) - 1)) &
> ~((typeof(addr))(size)-1))
>
> Which I assume the compiler will sort out?
[ This is line-wrapped, something in your mailer? Took me a bit to figure
out the - and + are diff -u things :-) ]
In the common case where size is a constant integer power of two, the
compiler will have no problem with this. But why do so complicated?
Why are the casts there, btw?
Segher
next prev parent reply other threads:[~2020-04-21 16:29 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-20 18:36 [PATCH 1/5] drivers/powerpc: Replace _ALIGN_UP() by ALIGN() Christophe Leroy
2020-04-20 18:36 ` [PATCH 2/5] powerpc: Replace _ALIGN_DOWN() by ALIGN_DOWN() Christophe Leroy
2020-04-21 1:04 ` Joel Stanley
2020-04-21 15:55 ` Segher Boessenkool [this message]
2020-04-20 18:36 ` [PATCH 3/5] powerpc: Replace _ALIGN_UP() by ALIGN() Christophe Leroy
2020-04-21 1:04 ` Joel Stanley
2020-04-20 18:36 ` [PATCH 4/5] powerpc: Replace _ALIGN() " Christophe Leroy
2020-04-21 1:11 ` Joel Stanley
2020-04-20 18:36 ` [PATCH 5/5] powerpc: Remove _ALIGN_UP(), _ALIGN_DOWN() and _ALIGN() Christophe Leroy
2020-04-21 1:04 ` Joel Stanley
2020-04-21 0:49 ` [PATCH 1/5] drivers/powerpc: Replace _ALIGN_UP() by ALIGN() Joel Stanley
2020-05-20 10:59 ` Michael Ellerman
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