counting-chars

Small and stupid benchmark of counting a char in a big string.

-O2

CPU	Naive	SSE4.2	AVX2
Ryzen 9 7950X3D (gcc 13)	712	88	56
Ryzen 9 7950X3D (clang 16)	464	83	45

-O3 -march=native

CPU	Naive	SSE4.2	AVX2
Ryzen 9 7950X3D (gcc 13)	76	83	70
Ryzen 9 7950X3D (clang 16)	62	81	42

Old ones

Older results, with gcc 9.2 and a somewhat different hardware:

CPU	Naive / -O2	Naive / -O3 -march=native	SSE4.2	AVX2
Core i7 3930k @ 4.0 GHz	1060	506	255	—
Core i7 4770	921	332	253	125
Core i7 6700	913	317	218	118
Ryzen 7 3700X	863	352	126	116

Generating test input

We use King James version of the bible from The Large Corpus here, concatenated 500 times with itself:

wget http://corpus.canterbury.ac.nz/resources/large.tar.gz
tar xf large.tar.gz bible.txt
for i in `seq 1 500`; do cat bible.txt >> bible_large.txt; done