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Re: master: Build failure in malloc with GCC 7

From: Andreas Schwab <schwab at suse dot de>
To: Florian Weimer <fweimer at redhat dot com>
Cc: GNU C Library <libc-alpha at sourceware dot org>, DJ Delorie <dj at redhat dot com>, Carlos O'Donell <carlos at redhat dot com>
Date: Wed, 12 Jul 2017 14:29:25 +0200
Subject: Re: master: Build failure in malloc with GCC 7
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References: <53780a28-ff3e-0c60-f9b2-f16f9580667d@redhat.com> <mvm60ey9gyx.fsf@suse.de> <8a31493c-6778-ca10-7469-77fff10b8b42@redhat.com> <a0e2feeb-4f0e-29f5-f0e2-c44f848ac3a5@redhat.com>

On Jul 12 2017, Florian Weimer <fweimer@redhat.com> wrote:

> The attached patch adds an assert which reveals to the GCC optimizers
> that the global_max_fast can never MAX_FAST_SIZE, so this particular
> issue goes away.  However, there is a cost in terms of code size because
> it affects many places in malloc.

Can __builtin_unreachable avoid the runtime overhead?

Andreas.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
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  - From: Florian Weimer
- Re: master: Build failure in malloc with GCC 7
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- Re: master: Build failure in malloc with GCC 7
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- Re: master: Build failure in malloc with GCC 7
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