On Monday, 5 September 2016 at 08:21:53 UTC, Andrei Alexandrescu
wrote:
What are the benchmarks and the numbers? What loss are you
looking at? -- Andrei
Just looking at the example, and referencing the map code in
std.algorithm.iteration, I can see multiple function calls
instead of one thanks to every indexing of the new map doing a
transformation instead of caching it. I'm not sure if the lambda
declaration there will result in the argument being taken by ref
or by value, but let's assume by value for the sake of argument.
Depending on if it's taking by value a reference or a value type,
that could either be a cheap function call or an expensive one.
But even if it took it by reference, it's still a function call.
Function calls are generally The Devil(TM) in a gaming
environment. The less you can make, the better.
Random aside: There are streaming store instructions available to
me on x86 platforms so that I don't have to wait for the
destination to hit L1 cache before writing. The pattern Manu
talks about with a batching function can better exploit this. But
I imagine copy could also take advantage of this when dealing
with value types.
