From 56182d163ef481283ad3b671f931d6228ed4e65f Mon Sep 17 00:00:00 2001
From: Taylor R Campbell <riastradh@NetBSD.org>
Date: Thu, 13 Jul 2023 20:33:06 +0000
Subject: [PATCH] sys/bitops.h: Use __builtin_ffs/ffsll/clz/clzll if available.

Make sure to test both versions of the code.
---
 sys/sys/bitops.h                       | 20 +++++++++++++++
 tests/include/sys/Makefile             |  1 +
 tests/include/sys/t_bitops_nobuiltin.c | 34 ++++++++++++++++++++++++++
 3 files changed, 55 insertions(+)
 create mode 100644 tests/include/sys/t_bitops_nobuiltin.c

diff --git a/sys/sys/bitops.h b/sys/sys/bitops.h
index b80fdc247214..f6a66d246a0b 100644
--- a/sys/sys/bitops.h
+++ b/sys/sys/bitops.h
@@ -40,6 +40,10 @@
 static __inline int __unused
 ffs32(uint32_t _n)
 {
+#if defined(__has_builtin) && __has_builtin(__builtin_ffs) && \
+    !defined(_SYS_BITOPS_NOBUILTIN)
+	return __builtin_ffs(_n);
+#else
 	int _v;
 
 	if (!_n)
@@ -67,6 +71,7 @@ ffs32(uint32_t _n)
 		_v += 1;
 	}
 	return _v;
+#endif
 }
 #endif
 
@@ -74,6 +79,10 @@ ffs32(uint32_t _n)
 static __inline int __unused
 ffs64(uint64_t _n)
 {
+#if defined(__has_builtin) && __has_builtin(__builtin_ffsl) && \
+    !defined(_SYS_BITOPS_NOBUILTIN)
+	return __builtin_ffsll(_n);
+#else
 	int _v;
 
 	if (!_n)
@@ -105,6 +114,7 @@ ffs64(uint64_t _n)
 		_v += 1;
 	}
 	return _v;
+#endif
 }
 #endif
 
@@ -115,6 +125,10 @@ ffs64(uint64_t _n)
 static __inline int __unused
 fls32(uint32_t _n)
 {
+#if defined(__has_builtin) && __has_builtin(__builtin_clz) && \
+    !defined(_SYS_BITOPS_NOBUILTIN)
+	return _n == 0 ? 0 : 32 - __builtin_clz(_n);
+#else
 	int _v;
 
 	if (!_n)
@@ -142,6 +156,7 @@ fls32(uint32_t _n)
 		_v -= 1;
 	}
 	return _v;
+#endif
 }
 #endif
 
@@ -149,6 +164,10 @@ fls32(uint32_t _n)
 static __inline int __unused
 fls64(uint64_t _n)
 {
+#if defined(__has_builtin) && __has_builtin(__builtin_clzll) && \
+    !defined(_SYS_BITOPS_NOBUILTIN)
+	return _n == 0 ? 0 : 64 - __builtin_clzll(_n);
+#else
 	int _v;
 
 	if (!_n)
@@ -180,6 +199,7 @@ fls64(uint64_t _n)
 		_v -= 1;
 	}
 	return _v;
+#endif
 }
 #endif
 
diff --git a/tests/include/sys/Makefile b/tests/include/sys/Makefile
index 25755bebfe3d..59c57b174e28 100644
--- a/tests/include/sys/Makefile
+++ b/tests/include/sys/Makefile
@@ -7,6 +7,7 @@ NOMAN=		# defined
 TESTSDIR=		${TESTSBASE}/include/sys
 
 TESTS_C+=		t_bitops
+TESTS_C+=		t_bitops_nobuiltin
 TESTS_C+=		t_bootblock
 TESTS_C+=		t_cdefs
 TESTS_C+=		t_list
diff --git a/tests/include/sys/t_bitops_nobuiltin.c b/tests/include/sys/t_bitops_nobuiltin.c
new file mode 100644
index 000000000000..dd5d67a8fc1d
--- /dev/null
+++ b/tests/include/sys/t_bitops_nobuiltin.c
@@ -0,0 +1,34 @@
+/*	$NetBSD$	*/
+
+/*-
+ * Copyright (c) 2023 The NetBSD Foundation, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#define	_SYS_BITOPS_NOBUILTIN
+
+#include <sys/cdefs.h>
+__RCSID("$NetBSD$");
+
+#include "t_bitops.c"