Re: [musl] [PATCH] add memcmpeq: memcmp that returns length of first mismatch

[Thorsten Glaser <tg@mirbsd.de>]

Markus Wichmann dixit:

>> > > +	for (; n >= sizeof(word) && *(word *)p1 == *(word *)p2; p1+=sizeof(word), p2+=sizeof(word), n-=sizeof(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’s an instant SIGBUS/SIGSEGV.

bye,
//mirabilos
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