From: "H. Peter Anvin" <hpa@zytor.com>
To: Joe Perches <joe@perches.com>, linux-arch <linux-arch@vger.kernel.org>
Cc: mingo@kernel.org, linux-kernel@vger.kernel.org,
tglx@linutronix.de, james.t.kukunas@intel.com,
hpa@linux.intel.com,
Linus Torvalds <torvalds@linux-foundation.org>,
David Miller <davem@davemloft.net>
Subject: Re: [tip:x86/asm] x86, bitops: Change bitops to be native operand size
Date: Sun, 10 Nov 2013 18:06:26 -0800 [thread overview]
Message-ID: <52803BA2.2080908@zytor.com> (raw)
In-Reply-To: <1384123457.3081.33.camel@joe-AO722>
On 11/10/2013 02:44 PM, Joe Perches wrote:
> (adding linux-arch, and possible patch below)
>
> On Sun, 2013-11-10 at 14:10 -0800, H. Peter Anvin wrote:
>> Yes, on the generic it is int.
>>
>> The problem is in part that some architectures have bitop
>> instructions with specific behavior.
>
> I think that all bitop indices should be changed
> to unsigned (int or long, probably long) for all
> arches.
>
> Is there any impediment to that?
>
It is at the very best misleading. On x86 bit indicies will be signed
no matter what the data type says, and having an unsigned data type
being interpreted as signed seems like really dangerous.
On the other hand, for the generic implementation unsigned long makes sense.
We might need a bitindex_t or something like that for it to be clean.
-hpa
next prev parent reply other threads:[~2013-11-11 2:06 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-17 1:15 [tip:x86/asm] x86, bitops: Change bitops to be native operand size tip-bot for H. Peter Anvin
2013-11-10 21:09 ` Joe Perches
2013-11-10 22:10 ` H. Peter Anvin
2013-11-10 22:44 ` Joe Perches
2013-11-11 2:06 ` H. Peter Anvin [this message]
2013-11-11 2:22 ` Joe Perches
2013-11-11 23:34 ` H. Peter Anvin
2013-11-12 2:54 ` Joe Perches
2013-11-12 3:15 ` Linus Torvalds
2013-11-12 4:08 ` Joe Perches
2013-11-12 8:52 ` Geert Uytterhoeven
2013-11-30 23:16 ` Rob Landley
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