From dc873d8c8f08143730139147f866480ce61eed1a Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Sun, 5 Feb 2023 13:25:45 -0800
Subject: [PATCH] ircd::m::event: Add exists_count() convenience; simplify
 various popcounts.

---
 include/ircd/m/event/event.h |  1 +
 matrix/event.cc              | 17 +++++++++++++++++
 matrix/event_auth.cc         |  9 ++-------
 matrix/event_prev.cc         |  9 ++-------
 4 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/include/ircd/m/event/event.h b/include/ircd/m/event/event.h
index e0f83ac53..9f9010771 100644
--- a/include/ircd/m/event/event.h
+++ b/include/ircd/m/event/event.h
@@ -26,6 +26,7 @@ namespace ircd::m
 
 	// parallel util; returns bitset
 	uint64_t exists(const vector_view<const id::event> &);
+	size_t exists_count(const vector_view<const id::event> &);
 
 	// Equality tests the event_id only! know this.
 	bool operator==(const event &a, const event &b);
diff --git a/matrix/event.cc b/matrix/event.cc
index 9937524b8..f2e866eb4 100644
--- a/matrix/event.cc
+++ b/matrix/event.cc
@@ -1044,6 +1044,23 @@ ircd::m::operator==(const event &a, const event &b)
 	return a.event_id == b.event_id;
 }
 
+size_t
+ircd::m::exists_count(const vector_view<const id::event> &event_ids)
+{
+	const auto mask
+	{
+		exists(event_ids)
+	};
+
+	const auto ret
+	{
+		__builtin_popcountl(mask)
+	};
+
+	assert(size_t(ret) <= event_ids.size());
+	return ret;
+}
+
 uint64_t
 ircd::m::exists(const vector_view<const id::event> &event_ids)
 {
diff --git a/matrix/event_auth.cc b/matrix/event_auth.cc
index 3f47e1b4f..d490dc7d5 100644
--- a/matrix/event_auth.cc
+++ b/matrix/event_auth.cc
@@ -87,17 +87,12 @@ const
 		return auth_event(i++);
 	});
 
-	const auto mask
-	{
-		m::exists({ids, i})
-	};
-
 	const auto ret
 	{
-		__builtin_popcountl(mask)
+		m::exists_count({ids, i})
 	};
 
-	assert(size_t(ret) <= max && size_t(ret) <= auth_events_count());
+	assert(ret <= max && ret <= auth_events_count());
 	return ret;
 }
 
diff --git a/matrix/event_prev.cc b/matrix/event_prev.cc
index 3a918178e..6f6b4bc3e 100644
--- a/matrix/event_prev.cc
+++ b/matrix/event_prev.cc
@@ -114,17 +114,12 @@ const
 		return prev_event(i++);
 	});
 
-	const auto mask
-	{
-		m::exists({ids, i})
-	};
-
 	const auto ret
 	{
-		__builtin_popcountl(mask)
+		m::exists_count({ids, i})
 	};
 
-	assert(size_t(ret) <= max && size_t(ret) <= prev_events_count());
+	assert(ret <= max && ret <= prev_events_count());
 	return ret;
 }