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Re: [patch] Use unaligned access on x86_64
- From: Rafael EspÃndola <rafael dot espindola at gmail dot com>
- To: Binutils <binutils at sourceware dot org>
- Cc: Cary Coutant <ccoutant at gmail dot com>
- Date: Wed, 27 May 2015 11:26:48 -0400
- Subject: Re: [patch] Use unaligned access on x86_64
- Authentication-results: sourceware.org; auth=none
- References: <CAG3jRe+iwbjGWdqG-0gTb-8yNWqDN=S-1iVLkNKP2cXEscONhA at mail dot gmail dot com> <CAG3jReKawoa9xU_1eQ9_dYj0HYa+80Dp4Noo27MiFbCY2be2mg at mail dot gmail dot com> <CAG3jReKrfVtt_P=9gUTB7k6=ehAyu9wqHYyqb+wNueGrJ_OCpQ at mail dot gmail dot com>
ping
On 20 May 2015 at 09:01, Rafael EspÃndola <rafael.espindola@gmail.com> wrote:
> ping.
>
> On 27 April 2015 at 15:09, Rafael EspÃndola <rafael.espindola@gmail.com> wrote:
>> I tested this on my linux workstation with a debug build of clang. The
>> results are still very interesting.
>>
>> The perf logs are attached.
>>
>> Cheers,
>> Rafael
>>
>>
>> On 24 April 2015 at 10:54, Rafael EspÃndola <rafael.espindola@gmail.com> wrote:
>>> Hi,
>>>
>>> x86_64 has exquisite support for unaligned loads. It is a shame not to use it.
>>>
>>> The attached patch avoids aligning archive members on x86_64. The
>>> results when linking clang are very interesting:
>>>
>>> * massif reports that the malloc memory usage goes from 331,295,192
>>> bytes to just 133,415,136 bytes.
>>>
>>> * the linking time (30 runs average) goes from
>>>
>>> 1.310065610 seconds time elapsed ( +- 0.19% )
>>>
>>> to
>>>
>>> 1.162564763 seconds time elapsed ( +- 0.14% )
>>>
>>>
>>> Cheers,
>>> Rafael
>>>
>>>
>>> 2015-04-24 Rafael Ãvila de EspÃndola <rafael.espindola@gmail.com>
>>>
>>> * fileread.cc (find_or_make_view): Don't align on x86_64.