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Date: Wed, 28 Feb 2024 23:14:27 +0000 (UTC)
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Subject: Re: [musl] [PATCH] add memcmpeq: memcmp that returns length of first
 mismatch

Markus Wichmann dixit:

>> > > +=09for (; n >=3D sizeof(word) && *(word *)p1 =3D=3D *(word *)p2; p1=
+=3Dsizeof(word), p2+=3Dsizeof(word), n-=3Dsizeof(word));

Very much UB.

>4. All the other musl C code avoids misaligned word access. I don't know
>which architecture/ABI doesn't allow it, but it is nevertheless the

Almost all of them. i386/amd64 penalise it heavily and it can cause
trouble when crossing page sizes, cacheline sizes, etc. as well. On
alpha, many ARM, SPARC, and others, it=E2=80=99s an instant SIGBUS/SIGSEGV.

bye,
//mirabilos
--=20
I believe no one can invent an algorithm. One just happens to hit upon it
when God enlightens him. Or only God invents algorithms, we merely copy the=
m.
If you don't believe in God, just consider God as Nature if you won't deny
existence.=09=09-- Coywolf Qi Hunt