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RE: [PATCH] Fix C++0x memory model for -fno-strict-volatile-bitfields on ARM

From: Bernd Edlinger <bernd dot edlinger at hotmail dot de>
To: Richard Biener <richard dot guenther at gmail dot com>
Cc: Jason Merrill <jason at redhat dot com>, "Joseph S. Myers" <joseph at codesourcery dot com>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Sandra Loosemore <sandra at codesourcery dot com>, Eric Botcazou <ebotcazou at adacore dot com>
Date: Mon, 25 Nov 2013 13:07:41 +0100
Subject: RE: [PATCH] Fix C++0x memory model for -fno-strict-volatile-bitfields on ARM
Authentication-results: sourceware.org; auth=none
References: <DUB122-W15E51EED0BDD4E4BBB7280E40D0 at phx dot gbl>,<CAFiYyc3B19C+KzWADqMuFftHBsf9R-BVmhx3byk4HMaHDZVCgQ at mail dot gmail dot com>,<DUB122-W349FBC26ACB80FE7DB42E7E40D0 at phx dot gbl>,<DUB122-W34629C286171333E30C282E40B0 at phx dot gbl>,<CAFiYyc2rzP3kt3O8GcDRFbae=YXFgUrjSTkwRpYv-CA3BzrjAQ at mail dot gmail dot com>,<DUB122-W30700270BEE314AA5EED7AE4FB0 at phx dot gbl>,<CAFiYyc0k-=C16YZ3mr7eP_i4f-O+FOXHLakepdnqK2hAW4vV4A at mail dot gmail dot com>,<DUB122-W45F353FDDFC7B5AA2D7AAE4E40 at phx dot gbl>

Hello,

I had forgotten to run the Ada test suite when I submitted the previous version of this patch.
And indeed there were some Ada test cases failing because in Ada packed structures are
like bit fields, but without the DECL_BIT_FIELD_TYPE attribute.

Please find attached the updated version of this patch.

Boot-strapped and regression-tested on x86_64-linux-gnu.
Ok for trunk?

Bernd.

> On Mon, 18 Nov 2013 11:37:05, Bernd Edlinger wrote:
>
> Hi,
>
> On Fri, 15 Nov 2013 13:30:51, Richard Biener wrote:
>>> That looks like always pretending it is a bit field.
>>> But it is not a bit field, and bitregion_start=bitregion_end=0
>>> means it is an ordinary value.
>>
>> I don't think it is supposed to mean that. It's supposed to mean
>> "the access is unconstrained".
>>
>
> Ok, agreed, I did not regard that as a feature.
> And apparently only the code path in expand_assigment
> really has a problem with it.
>
> So here my second attempt at fixing this.
>
> Boot-strapped and regression-tested on x86_64-linux-gnu.
>
> OK for trunk?
>
>
> Thanks
> Bernd.

Attachment: changelog-unaligned-data.txt
Description: Text document

Attachment: patch-unaligned-data.diff
Description: Binary data

References:
- Re: [PATCH] Fix C++0x memory model for -fno-strict-volatile-bitfields on ARM
  - From: Richard Biener
- RE: [PATCH] Fix C++0x memory model for -fno-strict-volatile-bitfields on ARM
  - From: Bernd Edlinger
- Re: [PATCH] Fix C++0x memory model for -fno-strict-volatile-bitfields on ARM
  - From: Richard Biener
- RE: [PATCH] Fix C++0x memory model for -fno-strict-volatile-bitfields on ARM
  - From: Bernd Edlinger

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