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Re: [PATCH] Fix for PR55492 : __atomic_load doesn't match ACQUIRE memory model

From: Andrew MacLeod <amacleod at redhat dot com>
To: Yvan Roux <yvan dot roux at linaro dot org>
Cc: gcc-patches at gcc dot gnu dot org
Date: Thu, 29 Nov 2012 12:01:07 -0500
Subject: Re: [PATCH] Fix for PR55492 : __atomic_load doesn't match ACQUIRE memory model
References: <CAD57uCc0hVb740SKkdLJf_BQtE=xHJ126zxNtbBeXHCjUn2LGA@mail.gmail.com>

On 11/29/2012 10:42 AM, Yvan Roux wrote:

Hi,

on ARMv7, the code generated for the __atomic_load builtins in the
__ATOMIC_ACQUIRE memory model, puts a memory barrier before the load, whereas
the semantic of the acquire memory model implies a barrier after.

The issue seems to be in expand_atomic_load which puts a memory fence before
the load in any memory model. The attached patch fixes the problem.

Patch is fine.

If you can confirm you have a copyright assignment on file I can take care of checking it in.

Andrew

Follow-Ups:
- Re: [PATCH] Fix for PR55492 : __atomic_load doesn't match ACQUIRE memory model
  - From: Yvan Roux

References:
- [PATCH] Fix for PR55492 : __atomic_load doesn't match ACQUIRE memory model
  - From: Yvan Roux

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