Re: Safe to use stdatomic.h?

From: brian m. carlson <sandals@crustytoothpaste.net>
Date: Mar 20, 2017, 23:22 UTC
Message-ID: <20170320232240.k3egololfj7wt5cf@genre.crustytoothpaste.net>
In-Reply-To: <000801d2a1b7$1ec41620$5c4c4260$@gmail.com>

On Mon, Mar 20, 2017 at 04:18:20PM -0400, Ben Peart wrote:

Show 10 quoted lines

> My college Jeff is working on a patch series to further parallelize the
> loading of the index.  As part of that patch, it would be nice to use the
> atomic_fetch_add function as that would be more efficient than creating a
> mutex simply to protect a variable so that it can be incremented.  I haven't
> seen any use of atomics yet in Git, nor anything that includes
> <stdatomic.h>.
> 
> GCC has supported them since 4.9 and Clang has supported them by default
> since 3.3.  Are there any compilers currently in use by Git that don't
> support these C11 functions?

At work, we're compiling for CentOS 6 and 7. CentOS 7 only has GCC 4.8, and CentOS 6 has something much older. This is code we ship to customers, so we can't rely on them having devtoolset installed for newer GCC.

I could support the argument for ditching RHEL/CentOS 5 support, but I expect other people might disagree. After all, we're still targeting C89.

-- 
brian m. carlson / brian with sandals: Houston, Texas, US
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