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Files
coreutils/tests
Pádraig Brady 45cdd85366 cut: -c: optimize extracting the start of a line
Performance was tested with GCC 16 on an i7-5600U with
CFLAGS='-march=native -O3 -flto' with the following setup:

$ yes | head -n10M > sl.in
$ yes $(yes eeeaae | head -n10K | paste -s -d' ') | head -n10K > llw.in
$ yes $(yes eeeaae | head -n9 | paste -s -d' ') | head -n1M > asw.in
$ yes $(yes éééááé | head -n9 | paste -s -d$'\xe2\x80\x83') |
   head -n1M > mbw.in

for type in sl llw asw mbw; do
  cat $type.in >/dev/null;
  for imp in '-before' '-after'; do
    echo ============ "${imp:-base}" $type ==============;
    for d in -c; do
      fields='-f1 -f10 -f100'
      test "$d" = "-c" && { fields='-c1 -c10 -c100000'; d=''; }
      for f in $fields; do
        for loc in C.UTF-8; do
          # Skip -b for UTF-8 as no different
          test "$loc" = C.UTF-8 && echo "$f" | grep -q -- -b \
           && continue
          # Skip multi-byte delimiter for C and not allowed
          test "$loc" = C && test $(echo -n "$d" | wc -c) -ge 4 \
           && continue
          bin=src/cut${imp}
          LC_ALL=$loc $bin $f $d /dev/null 2>/dev/null &&
          hyperfine --warmup=2 -m2 -M6 \
           "LC_ALL=$loc $bin $f $d $type.in >/dev/null" ||
          printf 'Benchmark 1: %s\n  unsupported\n\n' \
           "LC_ALL=$loc $bin $f $d $type.in >/dev/null"
        done;
      done;
    done;
  done;
done

After a little post-processing of the results, we get:

-- src/cut-before

| command       |       sl |      llw |      asw |      mbw |
| ------------- | -------- | -------- | -------- | -------- |
| UTF8 -c1      |  60.7 ms |  1.244 s | 123.5 ms | 515.2 ms |
| UTF8 -c10     |  39.3 ms |  1.248 s | 127.4 ms | 526.0 ms |
| UTF8 -c100000 |  39.4 ms |  1.242 s | 121.4 ms | 514.3 ms |

-- src/cut-after

| command       |       sl |      llw |      asw |      mbw |
| ------------- | -------- | -------- | -------- | -------- |
| UTF8 -c1      |  70.9 ms | 105.5 ms |  27.0 ms |  47.6 ms |
| UTF8 -c10     |  55.7 ms | 105.7 ms |  48.2 ms | 126.8 ms |
| UTF8 -c100000 |  55.2 ms |  1.596 s | 158.8 ms | 555.1 ms |

* src/cut.c (cut_characters_mode): Shortcut the line delimiter
search if finished processing characters.
* tests/cut/cut.pl: Add a test case.
2026-09-29 13:34:00 +01:00
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