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Date: Tue, 20 Sep 2016 19:57:32 +0200
From: Georg Sauthoff <>
Subject: Re: memchr() performance

On Mon, Sep 19, 2016 at 07:58:48PM +0200, Szabolcs Nagy wrote:
> * Georg Sauthoff <> [2016-09-19 15:29:53 +0200]:

> > Yes. Sure, ub means that anything can happen, but this case should be ok
> > with GCC - if the function is compiled in isolation in its own
> > translation unit.
> unless you use lto
> (which musl does not support now, but ppl are doing this)

Yes, with lto there is no isolation.

For lto you can do one of the following:

- write a version in pure assembler, doesn't have to be harder to read
  than a C version

- use the may_alias attribute (supported at least by GCC/Clang)

- apply the memcpy() trick:

Best regards

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