Re: Ternary operator performance improvements

2011/10/17 Ilia Alshanetsky <ilia@prohost.org>: > Seems like a good patch, +1 from me on inclusion into 5.4/HEAD. > > On Fri, Oct 14, 2011 at 2:08 PM, Arnaud Le Blanc <arnaud.lb@gmail.com> wrote: >> Hi, >> >> I've already posted this patch and it has since been reviewed and improved. >> I'm re-posting it for discussion before eventually commiting it. >> >> The ternary operator always copies its second or third operand, which is very >> slow compared to an if/else when the operand is an array for example: >> >> $a = range(0,9); >> >> // this takes 0.3 seconds here: >> >> for ($i = 0; $i < 5000000; ++$i) { >>        if (true) { >>                $b = $a; >>        } else { >>                $b = $a; >>        } >> } >> >> // this takes 3.8 seconds: >> >> for ($i = 0; $i < 5000000; ++$i) { >>        $b = true ? $a : $a; >> } >> >> I've tried to reduce the performance hit by avoiding the copy when possible >> (patch attached). >> >> Benchmark: >> >> Without patch: (the numbers are the time taken to run the code a certain >> amount of times) >> >> $int = 0; >> $ary = array(1,2,3,4,5,6,7,8,9); >> >> true ? 1 : 0        0.124 >> true ? 1+0 : 0      0.109 >> true ? $ary : 0     2.020 ! >> true ? $int : 0     0.103 >> true ? ${'ary'} : 0 2.290 ! >> true ?: 0           0.091 >> 1+0 ?: 0            0.086 >> $ary ?: 0           2.151 ! >> ${'var'} ?: 0       2.317 ! >> >> With patch: >> >> true ? 1 : 0        0.124 >> true ? 1+0 : 0      0.195 >> true ? $ary : 0     0.103 >> true ? $int : 0     0.089 >> true ? ${'ary'} : 0 0.103 >> true ?: 0           0.086 >> 1+0 ?: 0            0.159 >> $cv ?: 0            0.090 >> ${'var'} ?: 0       0.089 >> >> >> The array copying overhead is eliminated. There is however a slowdown in some >> of the cases, but overall there is no completely unexpected performance hit as >> it is the case currently. >> >> What do you think ? Is there any objection ? >> >> Best regards, >> >> -- >> PHP Internals - PHP Runtime Development Mailing List >> To unsubscribe, visit: http://www.php.net/unsub.php >> > > -- > PHP Internals - PHP Runtime Development Mailing List > To unsubscribe, visit: http://www.php.net/unsub.php > > +1 from me too. -- Regards, Felipe Pena