[PATCH x86_64] Update memcpy, mempcpy and memmove selection order for Excavator CPU BZ #19583

[H.J. Lu]

On Thu, Mar 17, 2016 at 3:52 AM, Pawar, Amit <Amit.Pawar@amd.com> wrote:
> This patch is fix for https://sourceware.org/bugzilla/show_bug.cgi?id=19583
>
> As per the suggestion, defining new bit_arch_Prefer_Fast_Copy_Backward and index_arch_Prefer_Fast_Copy_Backward feature bit macros to update IFUNC selection order for memcpy, memcpy_chk, mempcpy, mempcpy_chk, memmove and memmove_chk functions without affecting other targets. PFA patch and ChangeLog files to this mail. If OK please commit it from my side.
>
>

A few comments:

1. Since there is bit_arch_Fast_Copy_Backward already, please
add bit_arch_Avoid_AVX_Fast_Unaligned_Load instead.
2. Please verify that index_arch_XXX are the same and use
one index_arch_XXX to set all bits.  There are examples in
sysdeps/x86/cpu-features.c.
3. Please use proper ChangeLog format:

        * file (name of function, macro, ...): What changed.

-- 
H.J.