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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, 20 May 2015 09:01:01 -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>
On 27 April 2015 at 15:09, Rafael EspÃndola <email@example.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.
> On 24 April 2015 at 10:54, Rafael EspÃndola <firstname.lastname@example.org> wrote:
>> 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% )
>> 1.162564763 seconds time elapsed ( +- 0.14% )
>> 2015-04-24 Rafael Ãvila de EspÃndola <email@example.com>
>> * fileread.cc (find_or_make_view): Don't align on x86_64.