ircd: Add assume() convenience wrapping for __builtin_assume().

include/ircd/ircd.h

@@ -40,6 +40,7 @@
 // Project library interfaces
 //
 
+#include "util/assume.h"
 #include "util/mask.h"
 #include "string_view.h"
 #include "vector_view.h"

include/ircd/util/assume.h

@@ -0,0 +1,26 @@
+// The Construct
+//
+// Copyright (C) The Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2020 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_ASSUME_H
+
+namespace ircd { inline namespace util
+{
+	template<class T>
+	[[using gnu: always_inline, gnu_inline, artificial]]
+	extern inline void
+	assume(T&& expr)
+	{
+		assert(static_cast<T&&>(expr));
+		#if __has_builtin(__builtin_assume)
+			__builtin_assume(static_cast<T&&>(expr));
+		#endif
+	}
+}}