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Re: [v3 RFC] PATCH to memory asm ops in atomicity.h
- From: Richard Henderson <rth at redhat dot com>
- To: Jason Merrill <jason at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 16 Dec 2003 15:51:12 -0800
- Subject: Re: [v3 RFC] PATCH to memory asm ops in atomicity.h
- References: <xypbrq8jppq.fsf@miranda.boston.redhat.com>
On Tue, Dec 16, 2003 at 06:41:05PM -0500, Jason Merrill wrote:
> This patch is a followup to
>
> http://gcc.gnu.org/ml/gcc-patches/2003-01/msg00108.html
>
> which has been sitting in my tree for months. It makes memory I/O explicit
> by adding input/output operands for *__mem to the patterns that don't have
> them yet and removing the memory clobbers, which are thereby no longer
> necessary.
Why are you doing this? If these operations are used as
synchronization primitives, then a memory clobber *is*
necessary as a barrier to memory read/write movement.
r~