mirrors/yosys
3
0
Fork 0
mirror of https://github.com/YosysHQ/yosys synced 2025-08-22 19:17:55 +00:00
Code Activity

Improve commutative hashing.

Browse source 
The simple XOR `commutative_eat()` implementation produces a lot of collisions.
https://www.preprints.org/manuscript/201710.0192/v1/download is a useful reference on this topic.

Running the included `hashTest.cc` without the hashlib changes, I get 49,580,349 collisions.
The 49,995,000 (i,j) pairs (0 <= i < 10000, i < j < 10000) hash into only 414,651 unique hash values.
We get simple collisions like (0,1) colliding with (2,3).

With the hashlib changes, we get only 707,099 collisions and 49,287,901 unique hash values.
Much better! The `commutative_hash` implementation corresponds to `Sum(4)` in the paper
mentioned above.
This commit is contained in:
Robert O'Callahan 2025-08-19 03:21:54 +00:00
parent b0d709f6cf
commit 3a5742ffd2
3 changed files with 78 additions and 7 deletions
Download patch file Download diff file Expand all files Collapse all files

1
kernel/yosys_common.h
View file

@ -20,6 +20,7 @@
#ifndef YOSYS_COMMON_H
#define YOSYS_COMMON_H
#include <array>
#include <map>
#include <set>
#include <tuple>