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Re: movmem pattern and missed alignment

From: Eric Botcazou <ebotcazou at adacore dot com>
To: Alexander Monakov <amonakov at ispras dot ru>
Cc: gcc at gcc dot gnu dot org, Richard Biener <richard dot guenther at gmail dot com>, Michael Matz <matz at suse dot de>, Paul Koning <paulkoning at comcast dot net>
Date: Tue, 09 Oct 2018 08:41:40 +0200
Subject: Re: movmem pattern and missed alignment
References: <5FA92D6B-8718-4586-AB3C-61C40639888E@comcast.net> <A2E8CA2E-47EF-4716-898D-4B7003A69F94@gmail.com> <alpine.LNX.2.20.13.1810090848590.2469@monopod.intra.ispras.ru>

> It's not quite obvious what SSE has to do with this - any hint please?

SSE introduced alignment constraints into the non-strict-alignment target x86 
so people didn't really want to play by the rules of strict-alignment targets.

> (according to my quick check this changed between gcc-4.5 and gcc-4.6)

Possibly indeed, I remembered GCC 4.5 as being the turning point.

-- 
Eric Botcazou

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References:
- movmem pattern and missed alignment
  - From: Paul Koning
- Re: movmem pattern and missed alignment
  - From: Richard Biener
- Re: movmem pattern and missed alignment
  - From: Alexander Monakov

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