[ARM] Adding strlen.S

The patch adds strlen.S to contain the complementary preprocessor
logic to strlen-stub.c intended to provide #inclusion of alternative
.S implementations.

Initially we just include the existing strlen-armv7.S implementation.

We rewrite _ISA_ARMV7 in both strlen.S and strlen-stub.c to use the
underlying existing underlying defintion from arm_asm.h in order to
avoide including that file, this is in effect the first step towards a
move to ACLE predefines only.

Tested by building newlib and comparing libc.a binaries before and
after for all permutations of:

      Architectures:
        armv4 armv4t armv5 armv5t armv5te armv6 armv6j armv6k
        armv6z armv6kz armv6t2 armv6-m armv6s-m armv7 armv7-a
        armv7ve armv7-r armv7-m armv7e-m armv8-a iwmmxt iwmmxt2

      ISAs:
        thumb arm

      Optimization Levels:
        Os O2

      Excluding:
        armv6s-m -mthumb
        armv6-m -mthumb

        armv6zk -mthumb
        armv6z -mthumb
        armv6k -mthumb
        armv6j -mthumb

1 files changed, 48 insertions, 0 deletions

diff --git a/newlib/libc/machine/arm/strlen.S b/newlib/libc/machine/arm/strlen.S
new file mode 100644
index 000000000..b9fb86184
--- /dev/null
+++ b/newlib/libc/machine/arm/strlen.S
@@ -0,0 +1,48 @@
+/* Copyright (c) 2015 ARM Ltd.
+   All rights reserved.
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions are met:
+       * Redistributions of source code must retain the above copyright
+	 notice, this list of conditions and the following disclaimer.
+       * 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.
+       * Neither the name of the Linaro nor the
+	 names of its contributors may be used to endorse or promote products
+	 derived from this software without specific prior written permission.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
+   HOLDER 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.  */
+
+#include "acle-compat.h"
+
+#if defined __OPTIMIZE_SIZE__ || defined PREFER_SIZE_OVER_SPEED
+#if defined __thumb__ && !defined __thumb2__
+  /* Implemented in strlen-stub.c.  */
+
+#else
+  /* Implemented in strlen-stub.c.  */
+
+#endif
+
+#else /* defined __OPTIMIZE_SIZE__ || defined PREFER_SIZE_OVER_SPEED */
+#if defined __thumb__ && ! defined __thumb2__
+  /* Implemented in strlen-stub.c.  */
+
+#elif (__ARM_ARCH >= 7 && defined __ARM_ARCH_ISA_ARM) || defined __ARM_ARCH_6T2__
+#include "strlen-armv7.S"
+
+#else
+  /* Implemented in strlen-stub.c.  */
+#endif
+#endif