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Re: [PATCH, AArch64] Add optimized strchrnul

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).

Andrew Pinski

> regards, Kyle

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