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[PATCH 19/26] arm: Add optimized ffs for armv6t2
- From: Richard Henderson <rth at twiddle dot net>
- To: libc-ports at sourceware dot org
- Cc: Joseph Myers <joseph at codesourcery dot com>
- Date: Tue, 26 Feb 2013 19:16:19 -0800
- Subject: [PATCH 19/26] arm: Add optimized ffs for armv6t2
- References: <1361934986-17018-1-git-send-email-rth@twiddle.net>
Half the size of gcc 4.8's output.
---
* sysdeps/arm/armv6t2/ffs.S: New file.
* sysdeps/arm/armv6t2/ffsll.S: New file.
---
ports/sysdeps/arm/armv6t2/ffs.S | 34 +++++++++++++++++++++++++++
ports/sysdeps/arm/armv6t2/ffsll.S | 49 +++++++++++++++++++++++++++++++++++++++
2 files changed, 83 insertions(+)
create mode 100644 ports/sysdeps/arm/armv6t2/ffs.S
create mode 100644 ports/sysdeps/arm/armv6t2/ffsll.S
diff --git a/ports/sysdeps/arm/armv6t2/ffs.S b/ports/sysdeps/arm/armv6t2/ffs.S
new file mode 100644
index 0000000..765fb5d
--- /dev/null
+++ b/ports/sysdeps/arm/armv6t2/ffs.S
@@ -0,0 +1,34 @@
+/* Copyright (C) 2013 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+
+ .syntax unified
+ .text
+
+ENTRY(__ffs)
+ cmp r0, #0
+ ittt ne
+ rbitne r0, r0
+ clzne r0, r0
+ addne r0, r0, #1
+ bx lr
+END(__ffs)
+
+weak_alias (__ffs, ffs)
+weak_alias (__ffs, ffsl)
+libc_hidden_builtin_def (ffs)
diff --git a/ports/sysdeps/arm/armv6t2/ffsll.S b/ports/sysdeps/arm/armv6t2/ffsll.S
new file mode 100644
index 0000000..d428509
--- /dev/null
+++ b/ports/sysdeps/arm/armv6t2/ffsll.S
@@ -0,0 +1,49 @@
+/* Copyright (C) 2013 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+
+ .syntax unified
+ .text
+
+ENTRY(ffsll)
+ @ If low part is 0, operate on the high part. Ensure that the
+ @ word on which we operate is in r0. Set r2 to the bit offset
+ @ of the word being considered. Set the flags for the word
+ @ being operated on.
+#ifdef __ARMEL__
+ cmp r0, #0
+ itee ne
+ movne r2, #0
+ moveq r2, #32
+ movseq r0, r1
+#else
+ cmp r1, #0
+ ittee ne
+ movne r2, #0
+ movne r0, r1
+ moveq r2, #32
+ cmpeq r0, #0
+#endif
+ @ Perform the ffs on r0.
+ itttt ne
+ rbitne r0, r0
+ clzne r0, r0
+ addne r0, r0, #1
+ addne r0, r0, r2
+ bx lr
+END(ffsll)
--
1.8.1.2