From: Rasmus Villemoes <linux@rasmusvillemoes.dk>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andi Kleen <ak@linux.intel.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 2/2] include/linux: apply __malloc attribute
Date: Sat, 26 Mar 2016 20:06:13 +0100 [thread overview]
Message-ID: <87mvplukii.fsf@rasmusvillemoes.dk> (raw)
In-Reply-To: <20160324153639.bb996d7bf5a585dfb46740b7@linux-foundation.org> (Andrew Morton's message of "Thu, 24 Mar 2016 15:36:39 -0700")
On Thu, Mar 24 2016, Andrew Morton <akpm@linux-foundation.org> wrote:
> On Thu, 24 Mar 2016 00:42:32 +0100 Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote:
>
>> Attach the malloc attribute to a few allocation functions. This helps
>> gcc generate better code by telling it that the return value doesn't
>> alias any existing pointers (which is even more valuable given the
>> pessimizations implied by -fno-strict-aliasing).
>>
> Shaves 6 bytes off my 1MB i386 defconfig vmlinux. Winner!
Well, the full bloat-o-meter summary is
add/remove: 0/0 grow/shrink: 72/155 up/down: 1165/-1674 (-509)
which sure still isn't much, but this isn't (just) about saving a few
bytes, but more about allowing gcc to generate better code; sometimes by
not having to reload, but also by enabling it to reorder instructions
(e.g. hoisting a load above a store) - the simple example was chosen
because it was very easy to see the relationship between the source and
the generated code.
Anyway, thanks for picking them up.
Rasmus
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prev parent reply other threads:[~2016-03-26 19:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1458776553-9033-1-git-send-email-linux@rasmusvillemoes.dk>
2016-03-23 23:42 ` Rasmus Villemoes
2016-03-24 22:36 ` Andrew Morton
2016-03-26 19:06 ` Rasmus Villemoes [this message]
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