Re: [PATCH v1 7/9] diff --color-moved-ws: optimize allow-indentation-change

>
> From: Phillip Wood <phillip.wood@dunelm.org.uk>
>
> When running
>
>   git diff --color-moved-ws=allow-indentation-change v2.18.0 v2.19.0
>
> cmp_in_block_with_wsd() is called 694908327 times. Of those 42.7%
> return after comparing a and b. By comparing the lengths first we can
> return early in all but 0.03% of those cases without dereferencing the
> string pointers. The comparison between a and c fails in 6.8% of
> calls, by comparing the lengths first we reject all the failing calls
> without dereferencing the string pointers.
>
> This reduces the time to run the command above by by 42% from 14.6s to
> 8.5s. This is still much slower than the normal --color-moved which
> takes ~0.6-0.7s to run but is a significant improvement.
>
> The next commits will replace the current implementation with one that
> works with mixed tabs and spaces in the indentation. I think it is
> worth optimizing the current implementation first to enable a fair
> comparison between the two implementations.