[patch] Use unaligned access on x86_64

[Rafael Espíndola]

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 Espíndola <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 Ávila de Espíndola <rafael.espindola@gmail.com>
>
> * fileread.cc (find_or_make_view): Don't align on x86_64.
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