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Re: toolchain/53051: __atomic_is_lock_free missing on NetBSD/sparc
The following reply was made to PR lib/53051; it has been noted by GNATS.
From: David Young <dyoung%pobox.com@localhost>
Subject: Re: toolchain/53051: __atomic_is_lock_free missing on NetBSD/sparc
Date: Sat, 24 Feb 2018 15:37:03 -0600
On Sat, Feb 24, 2018 at 08:50:01PM +0000, maya%netbsd.org@localhost wrote:
> The following reply was made to PR toolchain/53051; it has been noted by GNATS.
> From: maya%netbsd.org@localhost
> To: gnats-bugs%NetBSD.org@localhost
> Subject: Re: toolchain/53051: __atomic_is_lock_free missing on NetBSD/sparc
> Date: Sat, 24 Feb 2018 20:47:46 +0000
> Never mind, the documentation even says it out loud (thanks for someone
> who read it out for me... :-))
> This built-in function returns true if objects of SIZE bytes always
> generate lock-free atomic instructions for the target
> architecture. If the built-in function is not known to be
> lock-free, a call is made to a runtime routine named
That paragraph may oversimplify things a bit? What if an object
is SIZE bytes but not naturally aligned?
Some readers may misunderstand "lock-free" to mean a non-interlocked
memory access (i.e., without LOCK prefix on x86) such as the
atomic_*_ni(3) functions provide on NetBSD, when the meaning is more
like a mutex, unless *I* have misunderstood.
dyoung%pobox.com@localhost Urbana, IL (217) 721-9981
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