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Groups > linux.kernel > #1401641
| From | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [patch V4 09/31] bitops: Add x86-specific parity functions |
| Date | 2016-05-16 19:10 +0200 |
| Message-ID | <rzubM-1me-15@gated-at.bofh.it> (permalink) |
| References | <rxxGP-4ls-49@gated-at.bofh.it> <rxytb-5fG-5@gated-at.bofh.it> <rxyMz-5vM-35@gated-at.bofh.it> <rzt61-rV-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Mon, May 16, 2016 at 11:49:05PM +0800, Zhaoxiu Zeng wrote:
> On 2016/5/11 17:31, Peter Zijlstra wrote:
> > Please use the GEN_*_RMWcc() stuff to avoid the setpo where possible.
>
> Setpo is better.
> In most cases, we need to store the parity, or compare it with other variables.
>
> For example, in drivers/net/ethernet/broadcom/tg3.c,
>
> static int tg3_test_nvram(struct tg3 *tp)
> {
> ......
> if (parity8(data[i]) == !!parity[i])
> goto out;
> ......
> }
>
> If use GEN_BINARY_RMWcc stuff，
>
> static inline unsigned int __arch_parity8(unsigned int w)
> {
> GEN_BINARY_RMWcc("testb", w, "er", 0xff, "%0", "po");
> }
blergh; GCC does indeed make a mess of that. It looks we'll need the
cc-output stuff for this in order for GCC to generates sane code for
that :/
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Re: [patch V4 09/31] bitops: Add x86-specific parity functions Zhaoxiu Zeng <zengzhaoxiu@163.com> - 2016-05-16 18:00 +0200
Re: [patch V4 09/31] bitops: Add x86-specific parity functions Peter Zijlstra <peterz@infradead.org> - 2016-05-16 19:10 +0200
Re: [patch V4 09/31] bitops: Add x86-specific parity functions "H. Peter Anvin" <hpa@zytor.com> - 2016-05-16 21:30 +0200
Re: [patch V4 09/31] bitops: Add x86-specific parity functions Peter Zijlstra <peterz@infradead.org> - 2016-05-17 13:30 +0200
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