From: Joe Perches <joe@perches.com>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: linux-arch <linux-arch@vger.kernel.org>,
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 18:22:50 -0800 [thread overview]
Message-ID: <1384136570.4771.5.camel@joe-AO722> (raw)
In-Reply-To: <52803BA2.2080908@zytor.com>
On Sun, 2013-11-10 at 18:06 -0800, H. Peter Anvin wrote:
> On 11/10/2013 02:44 PM, Joe Perches wrote:
> > 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.
Is there really any reason to introduce bitindex_t?
Perhaps the current x86 bitops asm code is being conflated
with the ideal implementation?
next prev parent reply other threads:[~2013-11-11 2:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <tip-z61ofiwe90xeyb461o72h8ya@git.kernel.org>
[not found] ` <1384117768.3081.10.camel@joe-AO722>
[not found] ` <5ac67859-a0b2-47f5-bdc2-c2a52b8d6885@email.android.com>
2013-11-10 22:44 ` [tip:x86/asm] x86, bitops: Change bitops to be native operand size Joe Perches
2013-11-10 22:44 ` Joe Perches
2013-11-11 2:06 ` H. Peter Anvin
2013-11-11 2:22 ` Joe Perches [this message]
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
2013-11-30 23:16 ` Rob Landley
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