powerpc64le: Optimized memmove for POWER10

This patch was initially based on the __memmove_power7 with some ideas
from strncpy implementation for Power 9.

Improvements from __memmove_power7:

1. Use lxvl/stxvl for alignment code.

   The code for Power 7 uses branches when the input is not naturally
   aligned to the width of a vector. The new implementation uses
   lxvl/stxvl instead which reduces pressure on GPRs. It also allows
   the removal of branch instructions, implicitly removing branch stalls
   and mispredictions.

2. Use of lxv/stxv and lxvl/stxvl pair is safe to use on Cache Inhibited
   memory.

   On Power 10 vector load and stores are safe to use on CI memory for
   addresses unaligned to 16B. This code takes advantage of this to
   do unaligned loads.

   The unaligned loads don't have a significant performance impact by
   themselves. However doing so decreases register pressure on GPRs
   and interdependence stalls on load/store pairs. This also improved
   readability as there are now less code paths for different alignments.
   Finally this reduces the overall code size.

3. Improved performance.

   This version runs on average about 30% better than memmove_power7
   for lengths  larger than 8KB. For input lengths shorter than 8KB
   the improvement is smaller, it has on average about 17% better
   performance.

   This version has a degradation of about 50% for input lengths
   in the 0 to 31 bytes range when dest is unaligned.

Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>

6 files changed, 66 insertions, 7 deletions

diff --git a/sysdeps/powerpc/powerpc64/multiarch/Makefile b/sysdeps/powerpc/powerpc64/multiarch/Makefile
index 8aa46a3..a82219c 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/Makefile
+++ b/sysdeps/powerpc/powerpc64/multiarch/Makefile
@@ -32,7 +32,8 @@ sysdep_routines += memcpy-power8-cached memcpy-power7 memcpy-a2 memcpy-power6 \
 		   strncase-power8
 
 ifneq (,$(filter %le,$(config-machine)))
-sysdep_routines += strcmp-power9 strncmp-power9 strcpy-power9 stpcpy-power9 \
+sysdep_routines += memmove-power10 \
+		   strcmp-power9 strncmp-power9 strcpy-power9 stpcpy-power9 \
 		   rawmemchr-power9 strlen-power9 strncpy-power9 stpncpy-power9 \
 		   strlen-power10
 endif
diff --git a/sysdeps/powerpc/powerpc64/multiarch/bcopy.c b/sysdeps/powerpc/powerpc64/multiarch/bcopy.c
index 04f3432..2840b17 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/bcopy.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/bcopy.c
@@ -22,8 +22,17 @@
 extern __typeof (bcopy) __bcopy_ppc attribute_hidden;
 /* __bcopy_power7 symbol is implemented at memmove-power7.S  */
 extern __typeof (bcopy) __bcopy_power7 attribute_hidden;
+#ifdef __LITTLE_ENDIAN__
+extern __typeof (bcopy) __bcopy_power10 attribute_hidden;
+#endif
 
 libc_ifunc (bcopy,
+#ifdef __LITTLE_ENDIAN__
+	     hwcap2 & (PPC_FEATURE2_ARCH_3_1 |
+		       PPC_FEATURE2_HAS_ISEL)
+	     && (hwcap & PPC_FEATURE_HAS_VSX)
+	     ? __bcopy_power10 :
+#endif
             (hwcap & PPC_FEATURE_HAS_VSX)
             ? __bcopy_power7
             : __bcopy_ppc);
diff --git a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
index 1a69936..d00bcc8 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
@@ -67,6 +67,13 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 
   /* Support sysdeps/powerpc/powerpc64/multiarch/memmove.c.  */
   IFUNC_IMPL (i, name, memmove,
+#ifdef __LITTLE_ENDIAN__
+	      IFUNC_IMPL_ADD (array, i, memmove,
+			      hwcap2 & (PPC_FEATURE2_ARCH_3_1 |
+					PPC_FEATURE2_HAS_ISEL)
+			      && (hwcap & PPC_FEATURE_HAS_VSX),
+			      __memmove_power10)
+#endif
 	      IFUNC_IMPL_ADD (array, i, memmove, hwcap & PPC_FEATURE_HAS_VSX,
 			      __memmove_power7)
 	      IFUNC_IMPL_ADD (array, i, memmove, 1, __memmove_ppc))
@@ -186,6 +193,13 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 
   /* Support sysdeps/powerpc/powerpc64/multiarch/bcopy.c.  */
   IFUNC_IMPL (i, name, bcopy,
+#ifdef __LITTLE_ENDIAN__
+	      IFUNC_IMPL_ADD (array, i, bcopy,
+			      hwcap2 & (PPC_FEATURE2_ARCH_3_1 |
+					PPC_FEATURE2_HAS_ISEL)
+			      && (hwcap & PPC_FEATURE_HAS_VSX),
+			      __bcopy_power10)
+#endif
 	      IFUNC_IMPL_ADD (array, i, bcopy, hwcap & PPC_FEATURE_HAS_VSX,
 			      __bcopy_power7)
 	      IFUNC_IMPL_ADD (array, i, bcopy, 1, __bcopy_ppc))
diff --git a/sysdeps/powerpc/powerpc64/multiarch/memmove-power10.S b/sysdeps/powerpc/powerpc64/multiarch/memmove-power10.S
new file mode 100644
index 0000000..171b329
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/multiarch/memmove-power10.S
@@ -0,0 +1,27 @@
+/* Optimized memmove implementation for POWER10.
+   Copyright (C) 2021 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
+   <https://www.gnu.org/licenses/>.  */
+
+#define MEMMOVE __memmove_power10
+
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(name)
+
+#undef __bcopy
+#define __bcopy __bcopy_power10
+
+#include <sysdeps/powerpc/powerpc64/le/power10/memmove.S>
diff --git a/sysdeps/powerpc/powerpc64/multiarch/memmove-power7.S b/sysdeps/powerpc/powerpc64/multiarch/memmove-power7.S
index d66da58..27b196d 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/memmove-power7.S
+++ b/sysdeps/powerpc/powerpc64/multiarch/memmove-power7.S
@@ -21,7 +21,7 @@
 #undef libc_hidden_builtin_def
 #define libc_hidden_builtin_def(name)
 
-#undef bcopy
-#define bcopy __bcopy_power7
+#undef __bcopy
+#define __bcopy __bcopy_power7
 
 #include <sysdeps/powerpc/powerpc64/power7/memmove.S>
diff --git a/sysdeps/powerpc/powerpc64/multiarch/memmove.c b/sysdeps/powerpc/powerpc64/multiarch/memmove.c
index 9bec61a..420c2f2 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/memmove.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/memmove.c
@@ -28,14 +28,22 @@
 # include "init-arch.h"
 
 extern __typeof (__redirect_memmove) __libc_memmove;
-
 extern __typeof (__redirect_memmove) __memmove_ppc attribute_hidden;
 extern __typeof (__redirect_memmove) __memmove_power7 attribute_hidden;
+#ifdef __LITTLE_ENDIAN__
+extern __typeof (__redirect_memmove) __memmove_power10 attribute_hidden;
+#endif
 
 libc_ifunc (__libc_memmove,
-            (hwcap & PPC_FEATURE_HAS_VSX)
-            ? __memmove_power7
-            : __memmove_ppc);
+#ifdef __LITTLE_ENDIAN__
+	     hwcap2 & (PPC_FEATURE2_ARCH_3_1 |
+		       PPC_FEATURE2_HAS_ISEL)
+	     && (hwcap & PPC_FEATURE_HAS_VSX)
+	     ? __memmove_power10 :
+#endif
+		     (hwcap & PPC_FEATURE_HAS_VSX)
+		     ? __memmove_power7
+		     : __memmove_ppc);
 
 #undef memmove
 strong_alias (__libc_memmove, memmove);