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From: NRK <nrk@disroot.org>
To: musl@lists.openwall.com
Cc: Viktor Reznov <yann.collet.is.not.a.perfectionist@gmail.com>
Subject: Re: [musl] [PATCH] Decreasing the number of divisions
Date: Wed, 17 Apr 2024 01:25:18 +0000	[thread overview]
Message-ID: <kq7ozupkdpannvt6fxnltuap4bhesjot5sbqhnwe5hpvey7nht@qj3jonh36ngt> (raw)
In-Reply-To: <Zh6LOBFx8ZCjHFTO@voyager>

> I played around with this change on godbolt: https://godbolt.org/z/9PoGK9zae

You're looking at clang -O3, if you use gcc -Os (usual for musl
users/distros) you'll notice that gcc actually ends up emitting a div
instruction, which are known to be slow.

But I don't think trying to optimize around gcc's bad codegen is the
right move. It's better to just not use -Os with gcc. Which musl already
does since commit b90841e25832.

- NRK

  reply	other threads:[~2024-04-17  1:25 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-16 13:29 Viktor Reznov
2024-04-16 14:29 ` Markus Wichmann
2024-04-17  1:25   ` NRK [this message]
2024-04-17  1:56     ` Markus Wichmann
2024-04-16 14:38 ` Rich Felker
     [not found]   ` <CAKs8_OKqKsLbG_Cf0DtDGeZDLdFkO1kDx6z5Fg_rQwPxPLGP6g@mail.gmail.com>
2024-04-16 16:55     ` Rich Felker
     [not found]       ` <CAKs8_OJ4evmTzAGVZ1Yccw+4Jj7v=RwEJWicwbSoeQwbvqav1Q@mail.gmail.com>
2024-04-17  0:09         ` [musl] " Rich Felker

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