From 0f164cb73d243a909a07b3c6ed09629b0b6349d0 Mon Sep 17 00:00:00 2001
From: naddy <>
Date: Fri, 26 Jun 2020 20:16:22 +0000
Subject: Provide an optimized implementation of ffs(3) in libc on
aarch64/powerpc/powerpc64, making use of the count leading zeros instruction.
Also add a brief regression test. ok deraadt@ kettenis@
---
src/regress/lib/libc/Makefile | 4 ++--
src/regress/lib/libc/ffs/Makefile | 6 ++++++
src/regress/lib/libc/ffs/ffs_test.c | 18 ++++++++++++++++++
3 files changed, 26 insertions(+), 2 deletions(-)
create mode 100644 src/regress/lib/libc/ffs/Makefile
create mode 100644 src/regress/lib/libc/ffs/ffs_test.c
(limited to 'src')
diff --git a/src/regress/lib/libc/Makefile b/src/regress/lib/libc/Makefile
index 3d0712f951..9ad3120961 100644
--- a/src/regress/lib/libc/Makefile
+++ b/src/regress/lib/libc/Makefile
@@ -1,4 +1,4 @@
-# $OpenBSD: Makefile,v 1.55 2020/03/23 03:01:21 schwarze Exp $
+# $OpenBSD: Makefile,v 1.56 2020/06/26 20:16:21 naddy Exp $
SUBDIR+= _setjmp
SUBDIR+= alloca arc4random-fork atexit
@@ -6,7 +6,7 @@ SUBDIR+= basename
SUBDIR+= cephes cxa-atexit
SUBDIR+= db dirname
SUBDIR+= env explicit_bzero
-SUBDIR+= fmemopen fnmatch fpclassify fread
+SUBDIR+= ffs fmemopen fnmatch fpclassify fread
SUBDIR+= gcvt getaddrinfo getcap getopt getopt_long glob
SUBDIR+= hsearch
SUBDIR+= ieeefp ifnameindex
diff --git a/src/regress/lib/libc/ffs/Makefile b/src/regress/lib/libc/ffs/Makefile
new file mode 100644
index 0000000000..1ad004394f
--- /dev/null
+++ b/src/regress/lib/libc/ffs/Makefile
@@ -0,0 +1,6 @@
+PROG= ffs_test
+
+# prevent constant folding and inlining of __builtin_ffs()
+CFLAGS+= -ffreestanding
+
+.include <bsd.regress.mk>
diff --git a/src/regress/lib/libc/ffs/ffs_test.c b/src/regress/lib/libc/ffs/ffs_test.c
new file mode 100644
index 0000000000..bc1e5c53c2
--- /dev/null
+++ b/src/regress/lib/libc/ffs/ffs_test.c
@@ -0,0 +1,18 @@
+/* $OpenBSD: ffs_test.c,v 1.1 2020/06/26 20:16:22 naddy Exp $ */
+/*
+ * Written by Christian Weisgerber <naddy@openbsd.org>.
+ * Public domain.
+ */
+
+#include <assert.h>
+#include <stdint.h>
+#include <string.h>
+
+int
+main(void)
+{
+ assert(ffs(0) == 0);
+ assert(ffs(0x8080) == 8);
+ assert(ffs(INT32_MIN) == 32);
+ return (0);
+}
--
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