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Date: Fri, 27 May 2011 20:41:00 -0000
From: Jason Merrill <jason@redhat.com>
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To: Aldy Hernandez <aldyh@redhat.com>
CC: Jeff Law <law@redhat.com>, gcc-patches <gcc-patches@gcc.gnu.org>,        Jakub Jelinek <jakub@redhat.com>
Subject: Re: [C++0x] contiguous bitfields race implementation
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On 05/26/2011 02:37 PM, Aldy Hernandez wrote:
> The narrowest integer mode containing the bit field is still 32, so we
> access the bitfield with an SI instruction as expected.

OK, then:

struct A
{
   int i: 4;
   int j: 4;
   int k: 8;
   int l: 8;
   int m: 8;
};

now the narrowest mode containing 'j' is QI/8, but it would still be 
safe to use SI.

Jason