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From: Will Deacon <will.deacon@arm.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Dave Martin <dave.martin@arm.com>,
	Richard Henderson <rth@twiddle.net>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: Re: [PATCH] genksyms: Teach parser about 128-bit built-in types
Date: Tue, 18 Jun 2019 17:20:21 +0100	[thread overview]
Message-ID: <20190618162021.GA4270@fuggles.cambridge.arm.com> (raw)
In-Reply-To: <CAK8P3a3phkiL8LFQM_AewMCE0EpQaCTOmgkVJe4x9oV84F4_7g@mail.gmail.com>

Hi Arnd,

On Tue, Jun 18, 2019 at 04:17:35PM +0200, Arnd Bergmann wrote:
> On Tue, Jun 18, 2019 at 3:10 PM Will Deacon <will.deacon@arm.com> wrote:
> >
> > +       { "__int128", BUILTIN_INT_KEYW },
> > +       { "__int128_t", BUILTIN_INT_KEYW },
> > +       { "__uint128_t", BUILTIN_INT_KEYW },
> 
> I wonder if it's safe to treat them as the same type, since
> __int128_t and __uint128_t differ in signedness.
> 
> If someone exports a symbol with one and changes it to the other, they
> would appear to be the same type.

My understanding is that the actual CRC generation for normal symbols is
based purely on the string-representation of the function signature, and
so the underlying type information isn't relevant to that. I can also
confirm that the CRC for an exported symbol that returns a __uint128_t
is not the same if you change it to return a __int128_t instead.

Will

  reply	other threads:[~2019-06-18 16:21 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-18 13:10 Will Deacon
2019-06-18 14:17 ` Arnd Bergmann
2019-06-18 16:20   ` Will Deacon [this message]
2019-06-21 16:57     ` Masahiro Yamada

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