Newer version of bitCount() #112
Merged
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This updates
ctrie.bitCount()
from "version 1" to "version 3" of Jörg Arndt's 32-bit bitcount function (according to http://www.jjj.de/bitwizardry/files/bitcount.h)I'm quite inexpert at these things, but benchmarking definitely suggests an improvement here (certainly it generates a lot less assembly). Hand-writing the assembly would probably be even better, but I suspect that might be beyond the realm of practical benefits, given that my general benchmarks suggest <4% of overall CPU time is spent here.