From: Alberto Gonzalez <boqwxp@airmail.cc>
Date: Fri, 24 Apr 2020 08:37:16 +0000 (+0000)
Subject: kernel: Ensure `dict` always hashes to the same value given the same contents.
X-Git-Tag: working-ls180~517^2~1
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=976edb7597692ac04111b3c51b13e18105c14f42;p=yosys.git

kernel: Ensure `dict` always hashes to the same value given the same contents.
---

diff --git a/kernel/hashlib.h b/kernel/hashlib.h
index 18114b6ad..1284f3f8d 100644
--- a/kernel/hashlib.h
+++ b/kernel/hashlib.h
@@ -207,6 +207,7 @@ class dict
 		entry_t() { }
 		entry_t(const std::pair<K, T> &udata, int next) : udata(udata), next(next) { }
 		entry_t(std::pair<K, T> &&udata, int next) : udata(std::move(udata)), next(next) { }
+		bool operator<(const entry_t &other) const { return udata.first < other.udata.first; }
 	};
 
 	std::vector<int> hashtable;
@@ -616,10 +617,12 @@ 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 (auto &it : entries) {
-			h = mkhash(h, hash_ops<K>::hash(it.udata.first));
-			h = mkhash(h, hash_ops<T>::hash(it.udata.second));
+		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));
 		}
 		return h;
 	}