[PATCH][ARM64] Improve ARM64 vector creation

[Tim Northover]

Hi Louis,

On 17 April 2014 20:55, Louis Gerbarg <lgg at apple.com> wrote:
> Currently when vectors are of mostly constant floating point values are created on ARM64 we do a lot of unnecessary inserts instead of duping the value across the vector. This patch fixes that, along with adding some patterns to be a bit a bit more efficient when that value is 0.0f.

Looks good to me! The test covered exactly the question I was about to
ask (what about const != 0?), given the code, which is always a good
sign.

Cheers.

Tim.