Re: Ternary operator performance improvements

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 >