faster splitter

[qznc via Digitalmars-d]

On Tuesday, 31 May 2016 at 19:29:25 UTC, Chris wrote:
> Would it speed things up even more, if we put the function 
> `computeSkip` into the loop or is this done automatically by 
> the compiler?

LDC inlines it. DMD does not.

More numbers:

./benchmark.ldc
Search in Alice in Wonderland
        std: 147 ±1
     manual: 100 ±0
       qznc: 121 ±1
      Chris: 103 ±1
     Andrei: 144 ±1
    Andrei2: 105 ±1
Search in random short strings
        std: 125 ±15
     manual: 117 ±10
       qznc: 104 ±6
      Chris: 123 ±14
     Andrei: 104 ±5
    Andrei2: 103 ±4
Mismatch in random long strings
        std: 140 ±22
     manual: 164 ±64
       qznc: 115 ±13
      Chris: 167 ±63
     Andrei: 161 ±68
    Andrei2: 106 ±9
Search random haystack with random needle
        std: 138 ±27
     manual: 135 ±33
       qznc: 116 ±16
      Chris: 141 ±36
     Andrei: 131 ±33
    Andrei2: 109 ±12
  (avg slowdown vs fastest; absolute deviation)
CPU ID: GenuineIntel Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz

Random short strings has haystacks of 10 to 300 characters and 
needles of 2 to 10. Basically, no time for initialisation.

Random long strings has haystacks of size 1000, 10_000, 100_000, 
or 1_000_000 and needles 50 to 500. It inserts a character into a 
random index of the needle to force a mismatch.

The last one is the configuration as before.

Overall, Andrei2 (the lazy compute skip) is really impressive. :)