[perl #130615] [PERF] Autoincrement much slower in sink context

[Zoffix Znet via RT]

On Sat, 21 Jan 2017 13:52:37 -0800, ale...@yahoo.com wrote:
> m: my int $i = 0; while $i < 10_000_000 {  $i++ }; say now - INIT
> now;rakudo-moar 7f245f: OUTPUT«5.1848902␤»
> m: my (int $i, int $nosink) = 0, 0; while $i < 10_000_000 {  $nosink =
> $i++ }; say now - INIT now;rakudo-moar 7f245f: OUTPUT«0.0816566␤»

More accurately: it's much faster when not sunk, as it gets optimized. Turn off 
the optimizer and the difference vanishes:

zoffix@VirtualBox:~$ perl6 -e 'my int $i = 0; while $i < 200_000 { $ = $i++; $ 
= 42 }; say now - INIT now;'                                                    
                                                                                
                
0.05608007
zoffix@VirtualBox:~$ perl6 -e 'my int $i = 0; while $i < 200_000 { $i++; $ = 42 
}; say now - INIT now;'                                                         
                                                                                
               
0.1869925
zoffix@VirtualBox:~$ perl6 --optimize=off -e 'my int $i = 0; while $i < 200_000 
{ $ = $i++; $ = 42 }; say now - INIT now;'
0.2641866
zoffix@VirtualBox:~$ perl6 --optimize=off -e 'my int $i = 0; while $i < 200_000 
{ $i++; $ = 42 }; say now - INIT now;'                                          
                                                                                
               
0.2896187