On 16/11/2018 20:40, Stefan Beller wrote:
On Fri, Nov 16, 2018 at 3:04 AM Phillip Wood <phillip.wood@xxxxxxxxxxxx> wrote:
From: Phillip Wood <phillip.wood@xxxxxxxxxxxxx>
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.
Up to here the series looks good and I think we could take it
as a preparatory self-standing series.
Thanks for looking at these, I think it makes sense to split the series
here, the commit message for this patch may want tweaking slightly if we
do. (I did wonder about splitting it in two when I submitted it but took
the easy way out.)
Best Wishes
Phillip
I'll read on.
Thanks,
Stefan
