arm: Add optimized ffs for armv6t2

diff --git a/ports/ChangeLog.arm b/ports/ChangeLog.arm
index 288dfb4c09dfa73b55d2985ffd1fb00910d9350f..55e63fa368baf26fb63b7407b2d93dc9c245cb66 100644 (file)
--- a/ports/ChangeLog.arm
+++ b/ports/ChangeLog.arm
@@ -1,5 +1,8 @@
 2013-03-06  Richard Henderson <rth@redhat.com>
 
+       * sysdeps/arm/armv6t2/ffs.S: New file.
+       * sysdeps/arm/armv6t2/ffsll.S: New file.
+
        * sysdeps/arm/sysdep.h (ARCH_HAS_HARD_TP): New macro.
        (GET_TLS): Use hard-tp if ARCH_HAS_HARD_TP.
        * sysdeps/unix/sysv/linux/arm/aeabi_read_tp.S: Likewise.

diff --git a/ports/sysdeps/arm/armv6t2/ffs.S b/ports/sysdeps/arm/armv6t2/ffs.S
new file mode 100644 (file)
index 0000000..b2c88b9
--- /dev/null
+++ b/ports/sysdeps/arm/armv6t2/ffs.S
@@ -0,0 +1,35 @@
+/* ffs -- find first set bit in an int, from least significant end.
+   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
+       rbit    r0, r0
+       itt     ne
+       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 (file)
index 0000000..e49c70f
--- /dev/null
+++ b/ports/sysdeps/arm/armv6t2/ffsll.S
@@ -0,0 +1,50 @@
+/* ffsll -- find first set bit in a long long, from least significant end.
+   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.
+       rbit    r0, r0
+       ittt    ne
+       clzne   r0, r0
+       addne   r2, r2, #1
+       addne   r0, r0, r2
+       bx      lr
+END (ffsll)