Performance test of short-circuiting AliasSeq

Tue Jun 2 08:27:36 UTC 2020

On Tuesday, 2 June 2020 at 06:52:00 UTC, Walter Bright wrote:
> On 6/1/2020 1:23 PM, Stefan Koch wrote:
>> TLDR; Performance patch caused a slowdown.
>> Why? Because the checking for the case which it wants to 
>> optimize takes more time than you safe by optimizing it.
>
> You'll need a finer grained profile to reach this conclusion 
> than the gross measurement of the compiler runtime. I suggest 
> using Vtune.

Oh hey, Vtune is free again for noncommercial use! Nice, there 
was a phase where it was only available commercially.

That said, for multi-run timings I'm very fond of multitime ( 
https://tratt.net/laurie/src/multitime/ ) and perf-tools can also 
give you good per-instruction analytics, though its presentation 
is not nearly as nice as vtune's.