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Re: [PATCH, AArch64] Add optimized strchrnul

On 10/12/14 09:38, Richard Earnshaw wrote:
> On 09/12/14 22:38, Andrew Pinski wrote:
>> On Wed, Dec 3, 2014 at 9:45 AM, Kyle McMartin <> wrote:
>>> On Wed, Nov 05, 2014 at 02:02:22PM +0000, Marcus Shawcroft wrote:
>>>> On 13 June 2014 11:23, Richard Earnshaw <> wrote:
>>>>> Here is an optimized implementation of __strchrnul.  The simplification
>>>>> that we don't have to track precisely why the loop terminates (match or
>>>>> end-of-string) means we have to do less work in both setup and the core
>>>>> inner loop.  That means this should never be slower than strchr.
>>>>> As with strchr, the use of LD1 means we do not need different versions
>>>>> for big-/little-endian.
>>>>> <date>  Richard Earnshaw  <>
>>>>>         * sysdeps/aarch64/strchrnul.S: New file.
>>>> Committed. + NEWS entry. /Marcus
>>> Hrm, I've bisected this commit as the cause of localedef segfaulting as
>>> part of install-locales... it ends up crashing weirdly inside of
>>> vsprintf's internals. Have either of you seen anything similar?
>> I just ran into this with an ILP32 compiled glibc (with thunderX
>> tuning and some extra patches) where printf was crashing.  The problem
>> is v15 is being used but it is a callee saved register.  Here is the
>> documentation from the ABI:
>> Registers v8-v15 must be preserved by a callee across subroutine
>> calls; the remaining registers (v0-v7, v16-v31)
>> do not need to be preserved (or should be preserved by the caller).
>> Thanks,
>> Andrew Pinski
>>> regards, Kyle
> Well spotted!  I'll push a fix round the various implementations of this
> R.

And here's the patch.

I'd commit this as obvious, but I don't have a commit bit for glibc :-(

	* sysdeps/aarch64/strchrnul.S (vrepmask): Use a call-clobbered


Attachment: glibc-strchrnul-reg.patch
Description: Text document

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