Re: [PATCH]: Add new bytecode op `switch' for implementing branch tables.

[Clément Pit-Claudel]

On 2017-02-08 08:38, Vibhav Pant wrote:
> On Tue, Feb 7, 2017 at 9:26 PM, Clément Pit-Claudel wrote:
>> The timings fluctuate quite a bit, but the byte-switch branch seems
>> to be about 5-7% slower.  Hopefully linear-scan hash tables will
>> make things much faster :)
>
> The following patch makes hash_lookup use linear search when the
> number of keys in the hash table is <= 5 (chosen arbitrarily). switch
> bytecode run with this patch takes 15.96 seconds to run the
> benchmark, while the goto-if-nil code takes 17.15 seconds.

Thanks! Indeed, here are new timings:

$ rm -f *.elc; emacs-byte-switch -Q --batch --eval '(byte-compile-file 
"eval-expr.el")'; time emacs-byte-switch -Q --batch -L . -l benchmark-expr.el

real    0m3.703s
user    0m3.664s
sys     0m0.012s

$ rm -f *.elc; emacs -Q --batch --eval '(byte-compile-file "eval-expr.el")'; 
time emacs -Q --batch -L . -l benchmark-expr.el

real    0m3.878s
user    0m3.860s
sys     0m0.016s

Things still fluctuate, but the byte-switch branch is now consistently faster, 
by roughly 5% :)

Clément.