From: "H. Peter Anvin" <hpa@zytor.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Denys Vlasenko <vda.linux@googlemail.com>,
linux-kernel@vger.kernel.org,
Douglas W Jones <jones@cs.uiowa.edu>,
Michal Nazarewicz <mnazarewicz@google.com>
Subject: Re: [PATCH 1/1] vsprintf: optimize decimal conversion (again)
Date: Mon, 26 Mar 2012 13:20:52 -0700 [thread overview]
Message-ID: <4F70CFA4.5020503@zytor.com> (raw)
In-Reply-To: <20120326131304.018a5f4b.akpm@linux-foundation.org>
On 03/26/2012 01:13 PM, Andrew Morton wrote:
> On Mon, 26 Mar 2012 21:56:38 +0200
> Denys Vlasenko <vda.linux@googlemail.com> wrote:
>
>>>> +#if BITS_PER_LONG != 32 || (~(0ULL)>>1) != ((1ULL<<63)-1)
>>>
>>> What's this for?
>>
>> The second check should be just BITS_PER_LONG_LONG != 64,
>> but we don't have BITS_PER_LONG_LONG.
>
> So let's add BITS_PER_LONG_LONG rather than hacking around its absence!
First of all, the #if is wrong: the preprocessor doesn't support data
types and does all arithmetic at (u)intmax_t precision.
As far as BITS_PER_LONG_LONG, there are tons of places in the kernel
which already require that long long is exactly 64 bits. That may or
may not be a good thing, but for right now one could simply:
#define BITS_PER_LONG_LONG 64
-hpa
next prev parent reply other threads:[~2012-03-26 20:21 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-26 18:47 [PATCH 0/1] vsprintf: optimize decimal conversion (again) Denys Vlasenko
2012-03-26 18:51 ` [PATCH 1/1] " Denys Vlasenko
2012-03-26 19:51 ` Andrew Morton
2012-03-26 19:56 ` Denys Vlasenko
2012-03-26 20:13 ` Andrew Morton
2012-03-26 20:18 ` Geert Uytterhoeven
2012-03-26 23:18 ` Denys Vlasenko
2012-03-27 0:30 ` Denys Vlasenko
2012-03-27 3:49 ` H. Peter Anvin
2012-03-26 20:20 ` H. Peter Anvin [this message]
2012-03-27 17:12 ` Michal Nazarewicz
2012-03-27 17:17 ` H. Peter Anvin
2012-03-27 0:26 ` Denys Vlasenko
2012-03-27 12:08 ` [PATCH 0/1] " roma1390
2012-03-27 15:32 ` Denys Vlasenko
2012-03-27 15:42 ` Denys Vlasenko
2012-03-28 5:56 ` roma1390
2012-03-28 10:13 ` Denys Vlasenko
2012-03-28 10:24 ` roma1390
2012-03-28 10:33 ` Denys Vlasenko
2012-03-28 10:39 ` roma1390
2012-03-28 11:20 ` Denys Vlasenko
2012-03-29 10:35 ` Denys Vlasenko
2012-03-28 10:31 ` roma1390
2012-03-28 11:23 ` Denys Vlasenko
2012-03-29 5:23 ` roma1390
2012-03-29 10:33 ` Denys Vlasenko
2012-03-27 13:49 ` roma1390
2012-03-27 15:33 ` Denys Vlasenko
2012-03-29 5:16 ` roma1390
2012-03-29 10:33 ` Denys Vlasenko
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