From 4d14399749a31cf18826548332a48c6418d5e7e0 Mon Sep 17 00:00:00 2001
From: "Emil J. Tywoniak" <emil@tywoniak.eu>
Date: Wed, 30 Oct 2024 10:49:17 +0100
Subject: [PATCH] hashlib: allow forcing Hasher state, use it for IdString
 trivial hashing

---
 kernel/hashlib.h | 7 +++++++
 kernel/rtlil.h   | 6 ++++++
 2 files changed, 13 insertions(+)

diff --git a/kernel/hashlib.h b/kernel/hashlib.h
index 33a1e04f8..aa9f43ff4 100644
--- a/kernel/hashlib.h
+++ b/kernel/hashlib.h
@@ -132,6 +132,13 @@ class Hasher {
 		state ^= t;
 	}
 
+	void force(hash_t new_state) {
+		state = new_state;
+	}
+
+	bool is_new() const {
+		return state == Hasher().state;
+	}
 };
 
 template<typename T>
diff --git a/kernel/rtlil.h b/kernel/rtlil.h
index a1f8668d0..b048b1a44 100644
--- a/kernel/rtlil.h
+++ b/kernel/rtlil.h
@@ -361,6 +361,12 @@ namespace RTLIL
 		}
 
 		Hasher hash_acc(Hasher h) const {
+			// If we're starting a hashing sequence, simply start with unhashed ID
+			if (h.is_new()) {
+				h.force((Hasher::hash_t) index_);
+				return h;
+			}
+
 			return hash_ops<int>::hash_acc(index_, h);
 		}