On 9/5/16 1:43 PM, Ethan Watson wrote:
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.
Understood. Would explicitly asking for vectorized operations be
acceptable? One school of thought has it that explicit invocation of
parallel operations are preferable to autovectorization and its ilk. --
Andrei
