From: Alberto Gonzalez <boqwxp@airmail.cc>
Date: Mon, 18 May 2020 17:10:01 +0000 (+0000)
Subject: kernel: Try an order-independent approach to hashing `dict`.
X-Git-Tag: working-ls180~517^2
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=6eea4b3d79590f874caa3ec740785781f3926666;p=yosys.git

kernel: Try an order-independent approach to hashing `dict`.

Co-Authored-By: David Shah <dave@ds0.me>
Co-Authored-By: Eddie Hung <eddie@fpgeh.com>
---

diff --git a/kernel/hashlib.h b/kernel/hashlib.h
index 1284f3f8d..5c87b55f5 100644
--- a/kernel/hashlib.h
+++ b/kernel/hashlib.h
@@ -617,12 +617,10 @@ public:
 	}
 
 	unsigned int hash() const {
-		std::vector<entry_t> entries_(entries); //make a copy to preserve const-ness
-		std::sort(entries_.begin(), entries_.end());
 		unsigned int h = mkhash_init;
-		for (unsigned int i = 0; i < entries_.size(); ++i) {
-			h = mkhash(h, hash_ops<K>::hash(entries_[i].udata.first));
-			h = mkhash(h, hash_ops<T>::hash(entries_[i].udata.second));
+		for (auto &entry : entries) {
+			h ^= hash_ops<K>::hash(entry.udata.first);
+			h ^= hash_ops<T>::hash(entry.udata.second);
 		}
 		return h;
 	}