From be07ae05b2abaa07ec09fa8de1d1d2b89fdd8201 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Thu, 4 Jun 2020 23:14:13 -0700
Subject: [PATCH] ircd::portable: Optimize redefined macro if conditions are
 favorable.

---
 include/ircd/assert.h   |  2 +-
 include/ircd/portable.h | 13 +++++++++++++
 include/ircd/stdinc.h   |  5 ++++-
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/include/ircd/assert.h b/include/ircd/assert.h
index 12ec29c06..eff141e24 100644
--- a/include/ircd/assert.h
+++ b/include/ircd/assert.h
@@ -35,7 +35,7 @@ namespace ircd
 {
 	void debugtrap() noexcept;
 	template<class expr> void always_assert(expr&&) noexcept;
-	void print_assertion(const char *const &, const char *const &, const unsigned &, const char *const &) noexcept;
+	[[gnu::cold]] void print_assertion(const char *const &, const char *const &, const unsigned &, const char *const &) noexcept;
 }
 
 /// Override the standard assert behavior to take one of several different
diff --git a/include/ircd/portable.h b/include/ircd/portable.h
index e1a0a1691..88c57288a 100644
--- a/include/ircd/portable.h
+++ b/include/ircd/portable.h
@@ -65,6 +65,19 @@ namespace ircd
 	typedef u_long ulong;
 #endif
 
+///TODO: XXX hoist lfence out of unlikely target block
+#if defined(RB_ASSERT) && defined(RB_ASSERT_INTRINSIC) && !defined(NDEBUG) && defined(__SSE2__)
+	#undef assert
+	#define assert(expr)                                                 \
+	({                                                                   \
+	    if(unlikely(!static_cast<bool>(expr)))                           \
+	    {                                                                \
+	        asm volatile ("lfence");                                     \
+	        __assert_fail(#expr, __FILE__, __LINE__, __FUNCTION__);      \
+	    }                                                                \
+	})
+#endif
+
 //
 // Trouble; clang w/ our custom assert
 //
diff --git a/include/ircd/stdinc.h b/include/ircd/stdinc.h
index bd5edd07f..6e40d45b1 100644
--- a/include/ircd/stdinc.h
+++ b/include/ircd/stdinc.h
@@ -26,7 +26,10 @@
 
 extern "C"
 {
-	#include <RB_INC_ASSERT_H
+	#ifndef assert
+		#include <RB_INC_ASSERT_H
+	#endif
+
 	#include <RB_INC_STDARG_H
 	#include <RB_INC_UNISTD_H
 	#include <RB_INC_SYS_TYPES_H