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From: Markus Wichmann <nullplan@gmx.net>
To: musl@lists.openwall.com
Subject: Re: max_align_t mess on i386
Date: Sun, 15 Dec 2019 06:47:46 +0100	[thread overview]
Message-ID: <20191215054746.GD20973@voyager> (raw)
In-Reply-To: <20191214151932.GW1666@brightrain.aerifal.cx>

On Sat, Dec 14, 2019 at 10:19:32AM -0500, Rich Felker wrote:
> The disadvantage of leaving max_align_t alone is that we have to
> (continue to) consider _Float128 an unsupported extension type whose
> use would be outside the scope of any guarantees we make, and that
> would need memalign to use. This is largely viable at present because
> it's a fringe thing, but we don't know if that will continue to be
> true far in the future.
>

It wouldn't just be that. Any application making use of SSE vector types
would have to use *memalign(). Apparently, there are libraries out there
that expect to get a 16byte alignment out of malloc(), or at least
that's what the author of dietlibc is alleging here:

https://blog.fefe.de/?ts=bac7bb06

Yes, it's German, but Google Translate exists. More importantly though,
it is from 2006, and he says he's "hacking about with" a bignum library,
and I don't know if he means his own or a public one. In any case,
though, the mere existance of SSE was cause enough for that man to
change the allocator to return a higher alignment on x86. Maybe one more
factor leaning towards the ABI change, right?

> Rich

Ciao,
Markus


  parent reply	other threads:[~2019-12-15  5:47 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-14 15:19 Rich Felker
2019-12-14 17:51 ` Florian Weimer
2019-12-14 18:17   ` Rich Felker
2019-12-14 18:53     ` Daniel Kolesa
2019-12-15 18:04   ` Rich Felker
2019-12-15  5:47 ` Markus Wichmann [this message]
2019-12-15 18:06 ` Jeffrey Walton
2019-12-15 18:22   ` Rich Felker
2019-12-16 15:30     ` Jeffrey Walton
2019-12-16 15:56       ` Rich Felker
2019-12-16 16:36         ` Jeffrey Walton
2019-12-16 17:49           ` Rich Felker
2019-12-16 16:40         ` Florian Weimer
2019-12-16 17:45           ` Rich Felker
2019-12-16 17:49             ` Florian Weimer
2019-12-16 17:51               ` Rich Felker
2019-12-15 18:23   ` Joakim Sindholt
2019-12-15 18:51     ` Rich Felker
2019-12-15 20:03       ` Alexander Monakov
2019-12-15 20:50         ` Szabolcs Nagy
2019-12-15 21:51         ` Jeffrey Walton

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