From fe0f398e14941d7f21cf372ec8a4888691c99886 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Tue, 7 Feb 2023 11:27:51 -0800
Subject: [PATCH] ircd::util: Add popcount wrapping; consolidate callsites.

---
 include/ircd/ircd.h          |  1 +
 include/ircd/m/query.h       |  2 +-
 include/ircd/simd/popcnt.h   |  7 +----
 include/ircd/util/bitset.h   |  2 +-
 include/ircd/util/popcount.h | 59 ++++++++++++++++++++++++++++++++++++
 matrix/event.cc              |  2 +-
 matrix/event_get.cc          |  2 +-
 matrix/event_index.cc        |  2 +-
 matrix/room_state_fetch.cc   |  2 +-
 9 files changed, 67 insertions(+), 12 deletions(-)
 create mode 100644 include/ircd/util/popcount.h

diff --git a/include/ircd/ircd.h b/include/ircd/ircd.h
index 8fa10bfd3..b25520d52 100644
--- a/include/ircd/ircd.h
+++ b/include/ircd/ircd.h
@@ -43,6 +43,7 @@
 #include "byte_view.h"
 #include "buffer/buffer.h"
 #include "vg.h"
+#include "util/popcount.h"
 #include "simd/simd.h"
 #include "simt/simt.h"
 #include "allocator/allocator.h"
diff --git a/include/ircd/m/query.h b/include/ircd/m/query.h
index a6eec974f..f04207fff 100644
--- a/include/ircd/m/query.h
+++ b/include/ircd/m/query.h
@@ -157,7 +157,7 @@ ircd::m::query(std::nothrow_t,
 
 	const auto got
 	{
-		__builtin_popcountl(mask)
+		popcount(mask)
 	};
 
 	return ret;
diff --git a/include/ircd/simd/popcnt.h b/include/ircd/simd/popcnt.h
index e36df75df..0ccb8801a 100644
--- a/include/ircd/simd/popcnt.h
+++ b/include/ircd/simd/popcnt.h
@@ -25,12 +25,7 @@ noexcept
 {
 	uint ret(0), i(0);
 	for(; i < lanes<T>(); ++i)
-		if constexpr(sizeof_lane<T>() <= sizeof(int))
-			ret += __builtin_popcount(a[i]);
-		else if constexpr(sizeof_lane<T>() <= sizeof(long))
-			ret += __builtin_popcountl(a[i]);
-		else
-			ret += __builtin_popcountll(a[i]);
+		ret += popcount(a[i]);
 
 	return ret;
 }
diff --git a/include/ircd/util/bitset.h b/include/ircd/util/bitset.h
index 58948573e..6f1dd4e08 100644
--- a/include/ircd/util/bitset.h
+++ b/include/ircd/util/bitset.h
@@ -132,7 +132,7 @@ const
 {
 	size_t ret(0);
 	for(size_t i(0); i < words; ++i)
-		ret += std::popcount(buf[i]);
+		ret += popcount(buf[i]);
 
 	return ret;
 }
diff --git a/include/ircd/util/popcount.h b/include/ircd/util/popcount.h
new file mode 100644
index 000000000..d0d639cb7
--- /dev/null
+++ b/include/ircd/util/popcount.h
@@ -0,0 +1,59 @@
+// The Construct
+//
+// Copyright (C) The Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2023 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+#pragma once
+#define HAVE_IRCD_UTIL_POPCOUNT_H
+
+namespace ircd {
+inline namespace util
+{
+	template<class T>
+	constexpr int popcount(const T) noexcept;
+
+	template<> constexpr int popcount(const unsigned long long) noexcept;
+	template<> constexpr int popcount(const unsigned long) noexcept;
+	template<> constexpr int popcount(const unsigned int) noexcept;
+}}
+
+template<>
+constexpr int
+ircd::util::popcount(const unsigned long long a)
+noexcept
+{
+	#if __has_feature(__cpp_lib_bitops)
+		return std::popcount(a);
+	#else
+		return __builtin_popcountll(a);
+	#endif
+}
+
+template<>
+constexpr int
+ircd::util::popcount(const unsigned long a)
+noexcept
+{
+	#if __has_feature(__cpp_lib_bitops)
+		return std::popcount(a);
+	#else
+		return __builtin_popcountl(a);
+	#endif
+}
+
+template<>
+constexpr int
+ircd::util::popcount(const unsigned int a)
+noexcept
+{
+	#if __has_feature(__cpp_lib_bitops)
+		return std::popcount(a);
+	#else
+		return __builtin_popcount(a);
+	#endif
+}
diff --git a/matrix/event.cc b/matrix/event.cc
index f2e866eb4..c4d570780 100644
--- a/matrix/event.cc
+++ b/matrix/event.cc
@@ -1054,7 +1054,7 @@ ircd::m::exists_count(const vector_view<const id::event> &event_ids)
 
 	const auto ret
 	{
-		__builtin_popcountl(mask)
+		popcount(mask)
 	};
 
 	assert(size_t(ret) <= event_ids.size());
diff --git a/matrix/event_get.cc b/matrix/event_get.cc
index c326f871f..aae93ba9f 100644
--- a/matrix/event_get.cc
+++ b/matrix/event_get.cc
@@ -240,7 +240,7 @@ ircd::m::get(const vector_view<const event::idx> &event_idx,
 
 	const auto found
 	{
-		__builtin_popcountl(mask)
+		popcount(mask)
 	};
 
 	if(unlikely(size_t(found) < event_idx.size()))
diff --git a/matrix/event_index.cc b/matrix/event_index.cc
index 2966496f1..14120da71 100644
--- a/matrix/event_index.cc
+++ b/matrix/event_index.cc
@@ -200,7 +200,7 @@ ircd::m::index(const vector_view<event::idx> &out_,
 			db::read(column, keys, bufs)
 		};
 
-		ret += __builtin_popcountl(found_mask);
+		ret += popcount(found_mask);
 	}
 
 	return ret;
diff --git a/matrix/room_state_fetch.cc b/matrix/room_state_fetch.cc
index 8a30fdbf4..9f893a52e 100644
--- a/matrix/room_state_fetch.cc
+++ b/matrix/room_state_fetch.cc
@@ -90,7 +90,7 @@ ircd::m::room_state_fetch_result(room::state::fetch &f,
 		};
 
 		f.responses += i;
-		f.exists += __builtin_popcountl(exists);
+		f.exists += popcount(exists);
 		for(size_t j(0); j < i; ++j)
 		{
 			if(exists & (1UL << j))