[libc-coord] Add new ABI '__memcmpeq()' to libc

[enh]

(Android libc maintainer.)

should __memcmpeq be in compiler-rt rather than libc?

On Thu, Sep 16, 2021 at 1:35 PM Joseph Myers <joseph@codesourcery.com>
wrote:

> On Thu, 16 Sep 2021, Chris Kennelly wrote:
>
> > In terms of relying on the feature:  If __memcmpeq is ever exposed as an
> a
> > simple alias for memcmp (since the notes mention that it's a valid
> > implementation), does that open up the possibility of depending on the
> > bcmp-like behavior that we were trying to escape?
>
> The proposal is as an ABI only (compilers would generate calls to
> __memcmpeq from boolean uses of memcmp, users wouldn't write calls to
> __memcmpeq directly, __memcmpeq wouldn't be declared in installed libc
> headers).  If such dependence arises, that would suggest a compiler bug
> wrongly generating such calls for non-boolean memcmp uses.
>
> --
> Joseph S. Myers
> joseph@codesourcery.com
>