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

From: Yvan Roux <yvan dot roux at linaro dot org>
To: gcc-patches at gcc dot gnu dot org
Date: Thu, 29 Nov 2012 16:42:41 +0100
Subject: [PATCH] Fix for PR55492 : __atomic_load doesn't match ACQUIRE memory model

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.

Thanks,
Yvan

Attachment: Fix-load-acquire.patch
Description: Binary data

Follow-Ups:
- Re: [PATCH] Fix for PR55492 : __atomic_load doesn't match ACQUIRE memory model
  - From: Andrew MacLeod
- Re: [PATCH] Fix for PR55492 : __atomic_load doesn't match ACQUIRE memory model
  - From: Marcus Shawcroft

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