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Subject: Re: [RFC] LKMM: Add volatile_if()
From:   Rasmus Villemoes <linux@rasmusvillemoes.dk>
To:     Linus Torvalds <torvalds@linux-foundation.org>,
        Alexander Monakov <amonakov@ispras.ru>
Cc:     Jakub Jelinek <jakub@redhat.com>,
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        Peter Zijlstra <peterz@infradead.org>,
        Will Deacon <will@kernel.org>,
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        Boqun Feng <boqun.feng@gmail.com>,
        Nick Piggin <npiggin@gmail.com>,
        David Howells <dhowells@redhat.com>,
        Jade Alglave <j.alglave@ucl.ac.uk>,
        Luc Maranget <luc.maranget@inria.fr>,
        Akira Yokosawa <akiyks@gmail.com>,
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Message-ID: <193ca8cf-cf2c-9372-c0ab-16714ec37f57@rasmusvillemoes.dk>
Date:   Mon, 7 Jun 2021 01:44:59 +0200
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On 07/06/2021 01.39, Rasmus Villemoes wrote:

> memory". Replacing with a call to an extern function marked pure does
> indeed cause gcc to cache the value of y*z, so in theory this should be
> possible, if one could convince gcc to "trust me, this really is a pure
> function".

Don't know why I didn't think to check before sending, but FWIW clang
doesn't need convincing, it already takes the __pure at face value and
caches y*z.

Rasmus