output

     11 bash: 2
      8 dash: 0
      3 dash: 3
     10 jsh: 0
      1 jsh: 3
     11 ksh: 3
     11 mksh: 0
     11 zsh: 2

return.bash

code='trap "(exit 2); return" USR1

f() {
    while :; do
	(exit 3) > "$fifo"
        sleep 0.5
    done

    return 5
}

{ read x < "$fifo"; kill -USR1 $$; } & (exit 7); f; echo $?
'

trap 'rm -f "$fifo"' EXIT
fifo=$(mktemp); rm -f "$fifo"; mkfifo "$fifo"; export fifo

shells=(
    bash
    ksh
    mksh
    dash
   # 'busybox sh'
    jsh
    zsh
)

for attempt in {0..10}; do
    time for shell in "${shells[@]}"; do
	printf '%s: %s\n' "$shell" "$($shell -c "$code")"
    done
done | sort | uniq -c