On Saturday, 28 May 2016 at 01:30:11 UTC, Andrei Alexandrescu
wrote:
On 05/27/2016 06:19 PM, qznc wrote:
manual find: 118 ±24
qznc find: 109 ±13 <--- using the sentinel trick
Chris find: 142 ±27
It is normal that the numbers of the other tests change, since
those are
relative to the fastest one in each run. When qznc find 'wins'
more
often, the others get more slowdown.
What compiler?
LDC. For DMD the numbers show no improvement:
std find: 170 ±31
manual find: 132 ±25
qznc find: 103 ±6
Chris find: 157 ±30
to
std find: 168 ±30
manual find: 131 ±25
qznc find: 104 ±8 <--- sentinel
Chris find: 155 ±29
(Caveat: Chris find has a bug, which is triggered once in the
10000 runs each.)
The sentinel trick is only proof of concept. The sentinel value
is `needleBack+1`, but range elements need not support addition.
Finding a sentinel is hard and most certainly requires more
assumptions about the ranges.
This means another special case for mutable ranges could be
worthwhile.
Also mind the throwing possibilities.
What do you mean? Using exceptions?
If anybody wants to replicate. It only takes a few seconds and
there are no dependencies except dmd/ldc.
git clone https://github.com/qznc/find-is-too-slow
cd find-is-too-slow
make dmd
make ldc
