arm: Implement memcpy ifunc selection in C

This patch refactor ARM memcpy ifunc selector to a C implementation.
No functional change is expected, including ifunc resolution rules.

It also adds some cleanup:

  - Internal memcpy hidden definition (__GI_memcpy) is now a hidden
    symbol.

  - No need to create hidden definition for the ifunc variants.

Checked on armv7-linux-gnueabihf and with a build for arm-linux-gnueabi,
arm-linux-gnueabihf with and without multiarch support and with both
GCC 7.1 and GCC mainline.  I also checked with the some possible
multiarch different configurations that trigger different memcpy
buids (__ARM_NEON__ && !__SOFT_FP__, !__ARM_NEON__ && !__SOFT_FP__, and
!__ARM_NEON__ && __SOFT_FP__).

	* sysdeps/arm/arm-ifunc.h: New file.
	* sysdeps/arm/armv7/multiarch/ifunc-memcpy.h: Likewise.
	* sysdeps/arm/armv7/multiarch/memcpy.c: Likewise.
	* sysdeps/arm/armv7/multiarch/memcpy_arm.S: Likewise.
	* sysdeps/arm/armv7/multiarch/rtld-memcpy.S: Likewise.
	* sysdeps/arm/armv7/multiarch/memcpy_neon.S [!__ARM_NEON__]
	(__memcpy_neon): Avoid create hidden alias.
	* sysdeps/arm/armv7/multiarch/memcpy_vfp.S [!__ARM_NEON_]
	(__memcpy_vfp): Likewise.
	* sysdeps/arm/armv7/multiarch/Makefile [$(subdir) = string]
	(sysdep_routines): Add memcpy_arm.
	* sysdeps/arm/armv7/multiarch/memcpy.S: Remove file.

Signed-off-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>

9 files changed, 124 insertions, 82 deletions

diff --git a/sysdeps/arm/arm-ifunc.h b/sysdeps/arm/arm-ifunc.h
new file mode 100644
index 0000000..52cb533
--- /dev/null
+++ b/sysdeps/arm/arm-ifunc.h
@@ -0,0 +1,33 @@
+/* Common definition for ifunc resolvers.  Linux/ARM version.
+   This file is part of the GNU C Library.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+
+   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>
+#include <ifunc-init.h>
+
+#define INIT_ARCH()
+
+#define arm_libc_ifunc_redirected(redirected_name, name, expr)	\
+  __ifunc (redirected_name, name, expr(hwcap), int hwcap, INIT_ARCH)
+
+#if defined SHARED
+# define arm_libc_ifunc_hidden_def(redirect_name, name) \
+  __hidden_ver1 (name, __GI_##name, redirect_name) \
+    __attribute__ ((visibility ("hidden")))
+#else
+# define arm_libc_ifunc_hidden_def(redirect_name, name)
+#endif
diff --git a/sysdeps/arm/armv7/multiarch/Makefile b/sysdeps/arm/armv7/multiarch/Makefile
index 9e1e61c..1e62ef9 100644
--- a/sysdeps/arm/armv7/multiarch/Makefile
+++ b/sysdeps/arm/armv7/multiarch/Makefile
@@ -1,3 +1,3 @@
 ifeq ($(subdir),string)
-sysdep_routines += memcpy_neon memcpy_vfp memchr_neon
+sysdep_routines += memcpy_neon memcpy_vfp memchr_neon memcpy_arm
 endif
diff --git a/sysdeps/arm/armv7/multiarch/ifunc-memcpy.h b/sysdeps/arm/armv7/multiarch/ifunc-memcpy.h
new file mode 100644
index 0000000..78cef2a
--- /dev/null
+++ b/sysdeps/arm/armv7/multiarch/ifunc-memcpy.h
@@ -0,0 +1,37 @@
+/* Common definition for memcpy resolver.
+   Copyright (C) 2017 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/>.  */
+
+#ifdef __SOFTFP__
+__typeof (REDIRECT_NAME) OPTIMIZE (arm) attribute_hidden;
+#endif
+__typeof (REDIRECT_NAME) OPTIMIZE (vfp) attribute_hidden;
+__typeof (REDIRECT_NAME) OPTIMIZE (neon) attribute_hidden;
+
+static inline void *
+IFUNC_SELECTOR (int hwcap)
+{
+  if (hwcap & HWCAP_ARM_NEON)
+    return OPTIMIZE (neon);
+#ifdef __SOFTFP__
+  if (hwcap & HWCAP_ARM_VFP)
+    return OPTIMIZE (vfp);
+  return OPTIMIZE (arm);
+#else
+  return OPTIMIZE (vfp);
+#endif
+}
diff --git a/sysdeps/arm/armv7/multiarch/memcpy.S b/sysdeps/arm/armv7/multiarch/memcpy.S
deleted file mode 100644
index 8a53bda..0000000
--- a/sysdeps/arm/armv7/multiarch/memcpy.S
+++ /dev/null
@@ -1,76 +0,0 @@
-/* Multiple versions of memcpy
-   All versions must be listed in ifunc-impl-list.c.
-   Copyright (C) 2013-2017 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/>.  */
-
-/* Thumb requires excess IT instructions here.  */
-#define NO_THUMB
-#include <sysdep.h>
-#include <rtld-global-offsets.h>
-
-#if IS_IN (libc)
-/* Under __ARM_NEON__, memcpy_neon.S defines the name memcpy.  */
-# ifndef __ARM_NEON__
-	.text
-ENTRY(memcpy)
-	.type	memcpy, %gnu_indirect_function
-# ifdef __SOFTFP__
-	ldr	r1, .Lmemcpy_arm
-	tst	r0, #HWCAP_ARM_VFP
-	ldrne	r1, .Lmemcpy_vfp
-# else
-	ldr	r1, .Lmemcpy_vfp
-# endif
-	tst	r0, #HWCAP_ARM_NEON
-	ldrne	r1, .Lmemcpy_neon
-1:
-	add	r0, r1, pc
-	DO_RET(lr)
-
-# ifdef __SOFTFP__
-.Lmemcpy_arm:
-	.long	C_SYMBOL_NAME(__memcpy_arm) - 1b - PC_OFS
-# endif
-.Lmemcpy_neon:
-	.long	C_SYMBOL_NAME(__memcpy_neon) - 1b - PC_OFS
-.Lmemcpy_vfp:
-	.long	C_SYMBOL_NAME(__memcpy_vfp) - 1b - PC_OFS
-
-END(memcpy)
-
-libc_hidden_builtin_def (memcpy)
-#endif  /* Not __ARM_NEON__.  */
-
-/* These versions of memcpy are defined not to clobber any VFP or NEON
-   registers so they must always call the ARM variant of the memcpy code.  */
-strong_alias (__memcpy_arm, __aeabi_memcpy)
-strong_alias (__memcpy_arm, __aeabi_memcpy4)
-strong_alias (__memcpy_arm, __aeabi_memcpy8)
-libc_hidden_def (__memcpy_arm)
-
-#undef libc_hidden_builtin_def
-#define libc_hidden_builtin_def(name)
-#undef weak_alias
-#define weak_alias(x, y)
-#undef libc_hidden_def
-#define libc_hidden_def(name)
-
-#define memcpy __memcpy_arm
-
-#endif
-
-#include "memcpy_impl.S"
diff --git a/sysdeps/arm/armv7/multiarch/memcpy.c b/sysdeps/arm/armv7/multiarch/memcpy.c
new file mode 100644
index 0000000..b94a017
--- /dev/null
+++ b/sysdeps/arm/armv7/multiarch/memcpy.c
@@ -0,0 +1,35 @@
+/* Multiple versions of memcpy.
+   All versions must be listed in ifunc-impl-list.c.
+   Copyright (C) 2017 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/>.  */
+
+/* For __ARM_NEON__ memchr_neon.S defines memchr directly and ifunc
+   is not used.  */
+#if IS_IN (libc) && !defined (__ARM_NEON__)
+# define memcpy __redirect_memcpy
+# include <string.h>
+# undef memcpy
+
+# include <arm-ifunc.h>
+
+# define SYMBOL_NAME memcpy
+# include "ifunc-memcpy.h"
+
+arm_libc_ifunc_redirected (__redirect_memcpy, memcpy, IFUNC_SELECTOR);
+
+arm_libc_ifunc_hidden_def (__redirect_memcpy, memcpy);
+#endif
diff --git a/sysdeps/arm/armv7/multiarch/memcpy_arm.S b/sysdeps/arm/armv7/multiarch/memcpy_arm.S
new file mode 100644
index 0000000..e4a9a68
--- /dev/null
+++ b/sysdeps/arm/armv7/multiarch/memcpy_arm.S
@@ -0,0 +1,10 @@
+#define memcpy __memcpy_arm
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(a)
+#include "memcpy_impl.S"
+
+/* These versions of memcpy are defined not to clobber any VFP or NEON
+   registers so they must always call the ARM variant of the memcpy code.  */
+strong_alias (__memcpy_arm, __aeabi_memcpy)
+strong_alias (__memcpy_arm, __aeabi_memcpy4)
+strong_alias (__memcpy_arm, __aeabi_memcpy8)
diff --git a/sysdeps/arm/armv7/multiarch/memcpy_neon.S b/sysdeps/arm/armv7/multiarch/memcpy_neon.S
index e60d1cc..1a8d8bb 100644
--- a/sysdeps/arm/armv7/multiarch/memcpy_neon.S
+++ b/sysdeps/arm/armv7/multiarch/memcpy_neon.S
@@ -1,8 +1,8 @@
-#ifdef __ARM_NEON__
-/* Under __ARM_NEON__, this file defines memcpy directly.  */
-libc_hidden_builtin_def (memcpy)
-#else
+/* For __ARM_NEON__ this file defines memcpy.  */
+#ifndef __ARM_NEON__
 # define memcpy __memcpy_neon
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(a)
 #endif
 
 #define MEMCPY_NEON
diff --git a/sysdeps/arm/armv7/multiarch/memcpy_vfp.S b/sysdeps/arm/armv7/multiarch/memcpy_vfp.S
index e008c04..d1e9ede 100644
--- a/sysdeps/arm/armv7/multiarch/memcpy_vfp.S
+++ b/sysdeps/arm/armv7/multiarch/memcpy_vfp.S
@@ -1,7 +1,9 @@
-/* Under __ARM_NEON__, memcpy_neon.S defines memcpy directly
+/* Under __ARM_NEON__ memcpy_neon.S defines memcpy directly
    and the __memcpy_vfp code will never be used.  */
 #ifndef __ARM_NEON__
 # define MEMCPY_VFP
 # define memcpy __memcpy_vfp
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(a)
 # include "memcpy_impl.S"
 #endif
diff --git a/sysdeps/arm/armv7/multiarch/rtld-memcpy.S b/sysdeps/arm/armv7/multiarch/rtld-memcpy.S
new file mode 100644
index 0000000..ca23875
--- /dev/null
+++ b/sysdeps/arm/armv7/multiarch/rtld-memcpy.S
@@ -0,0 +1 @@
+#include <sysdeps/arm/armv7/multiarch/memcpy_impl.S>