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>

8 files changed, 388 insertions, 7 deletions

diff --git a/sysdeps/powerpc/powerpc64/le/power10/memmove.S b/sysdeps/powerpc/powerpc64/le/power10/memmove.S
new file mode 100644
index 0000000..7dfd57e
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/le/power10/memmove.S
@@ -0,0 +1,320 @@
+/* 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/>.  */
+
+#include <sysdep.h>
+
+
+/* void* [r3] memmove (void *dest [r3], const void *src [r4], size_t len [r5])
+
+   This optimization checks if 'src' and 'dst' overlap.  If they do not
+   or 'src' is ahead of 'dest' then it copies forward.
+   Otherwise, an optimized backward copy is used.  */
+
+#ifndef MEMMOVE
+# define MEMMOVE memmove
+#endif
+	.machine power9
+ENTRY_TOCLESS (MEMMOVE, 5)
+	CALL_MCOUNT 3
+
+L(_memmove):
+	.p2align 5
+	/* Check if there is overlap, if so it will branch to backward copy.  */
+	subf	r9,r4,r3
+	cmpld	cr7,r9,r5
+	blt	cr7,L(memmove_bwd)
+
+	/* Fast path for length shorter than 16 bytes.  */
+	sldi	r7,r5,56
+	lxvl	32+v2,r4,r7
+	stxvl	32+v2,r3,r7
+	subic.	r8,r5,16
+	blelr
+
+	/* For shorter lengths aligning the dest address to 16 bytes either
+	   decreases performance or is irrelevant.  I'm making use of this
+	   comparison to skip the alignment in.  */
+	cmpldi	cr6,r5,256
+	bge	cr6,L(ge_256)
+	/* Account for the first 16-byte copy.  */
+	addi	r4,r4,16
+	addi	r11,r3,16	/* use r11 to keep dest address on r3.  */
+	subi	r5,r5,16
+	b	L(loop_head)
+
+	.p2align 5
+L(ge_256):
+	/* Account for the first copy <= 16 bytes.  This is necessary for
+	   memmove because at this point the src address can be in front of the
+	   dest address.  */
+	clrldi	r9,r5,56
+	li	r8,16
+	cmpldi	r9,16
+	iselgt	r9,r8,r9
+	add	r4,r4,r9
+	add	r11,r3,r9	/* use r11 to keep dest address on r3.  */
+	sub	r5,r5,r9
+
+	/* Align dest to 16 bytes.  */
+	neg	r7,r3
+	clrldi.	r9,r7,60
+	beq	L(loop_head)
+
+	.p2align 5
+	sldi	r6,r9,56
+	lxvl	32+v0,r4,r6
+	stxvl	32+v0,r11,r6
+	sub	r5,r5,r9
+	add	r4,r4,r9
+	add	r11,r11,r9
+
+L(loop_head):
+	cmpldi	r5,63
+	ble	L(final_64)
+
+	srdi.	r7,r5,7
+	beq	L(loop_tail)
+
+	mtctr	r7
+
+/* Main loop that copies 128 bytes each iteration.  */
+	.p2align 5
+L(loop):
+	addi	r9,r4,64
+	addi	r10,r11,64
+
+	lxv	32+v0,0(r4)
+	lxv	32+v1,16(r4)
+	lxv	32+v2,32(r4)
+	lxv	32+v3,48(r4)
+
+	stxv	32+v0,0(r11)
+	stxv	32+v1,16(r11)
+	stxv	32+v2,32(r11)
+	stxv	32+v3,48(r11)
+
+	addi	r4,r4,128
+	addi	r11,r11,128
+
+	lxv	32+v4,0(r9)
+	lxv	32+v5,16(r9)
+	lxv	32+v6,32(r9)
+	lxv	32+v7,48(r9)
+
+	stxv	32+v4,0(r10)
+	stxv	32+v5,16(r10)
+	stxv	32+v6,32(r10)
+	stxv	32+v7,48(r10)
+
+	bdnz	L(loop)
+	clrldi.	r5,r5,57
+	beqlr
+
+/* Copy 64 bytes.  */
+	.p2align 5
+L(loop_tail):
+	cmpldi 	cr5,r5,63
+	ble	cr5,L(final_64)
+
+	lxv	32+v0,0(r4)
+	lxv	32+v1,16(r4)
+	lxv	32+v2,32(r4)
+	lxv	32+v3,48(r4)
+
+	stxv	32+v0,0(r11)
+	stxv	32+v1,16(r11)
+	stxv	32+v2,32(r11)
+	stxv	32+v3,48(r11)
+
+	addi	r4,r4,64
+	addi	r11,r11,64
+	subi	r5,r5,64
+
+/* Copies the last 1-63 bytes.  */
+	.p2align 5
+L(final_64):
+	/* r8 holds the number of bytes that will be copied with lxv/stxv.  */
+	clrrdi.	r8,r5,4
+	beq	L(tail1)
+
+	cmpldi  cr5,r5,32
+	lxv	32+v0,0(r4)
+	blt	cr5,L(tail2)
+
+	cmpldi	cr6,r5,48
+	lxv	32+v1,16(r4)
+	blt	cr6,L(tail3)
+
+	.p2align 5
+	lxv	32+v2,32(r4)
+	stxv	32+v2,32(r11)
+L(tail3):
+	stxv	32+v1,16(r11)
+L(tail2):
+	stxv	32+v0,0(r11)
+	sub	r5,r5,r8
+	add	r4,r4,r8
+	add	r11,r11,r8
+	.p2align 5
+L(tail1):
+	sldi	r6,r5,56
+	lxvl	v4,r4,r6
+	stxvl	v4,r11,r6
+	blr
+
+/* If dest and src overlap, we should copy backwards.  */
+L(memmove_bwd):
+	add	r11,r3,r5
+	add	r4,r4,r5
+
+	/* Optimization for length smaller than 16 bytes.  */
+	cmpldi	cr5,r5,15
+	ble	cr5,L(tail1_bwd)
+
+	/* For shorter lengths the alignment either slows down or is irrelevant.
+	   The forward copy uses a already need 256 comparison for that.  Here
+	   it's using 128 as it will reduce code and improve readability.  */
+	cmpldi	cr7,r5,128
+	blt	cr7,L(bwd_loop_tail)
+
+	/* Align dest address to 16 bytes.  */
+	.p2align 5
+	clrldi.	r9,r11,60
+	beq	L(bwd_loop_head)
+	sub	r4,r4,r9
+	sub	r11,r11,r9
+	lxv	32+v0,0(r4)
+	sldi	r6,r9,56
+	stxvl   32+v0,r11,r6
+	sub	r5,r5,r9
+
+L(bwd_loop_head):
+	srdi.	r7,r5,7
+	beq	L(bwd_loop_tail)
+
+	mtctr	r7
+
+/* Main loop that copies 128 bytes every iteration.  */
+	.p2align 5
+L(bwd_loop):
+	addi	r9,r4,-64
+	addi	r10,r11,-64
+
+	lxv	32+v0,-16(r4)
+	lxv	32+v1,-32(r4)
+	lxv	32+v2,-48(r4)
+	lxv	32+v3,-64(r4)
+
+	stxv	32+v0,-16(r11)
+	stxv	32+v1,-32(r11)
+	stxv	32+v2,-48(r11)
+	stxv	32+v3,-64(r11)
+
+	addi	r4,r4,-128
+	addi	r11,r11,-128
+
+	lxv	32+v0,-16(r9)
+	lxv	32+v1,-32(r9)
+	lxv	32+v2,-48(r9)
+	lxv	32+v3,-64(r9)
+
+	stxv	32+v0,-16(r10)
+	stxv	32+v1,-32(r10)
+	stxv	32+v2,-48(r10)
+	stxv	32+v3,-64(r10)
+
+	bdnz	L(bwd_loop)
+	clrldi.	r5,r5,57
+	beqlr
+
+/* Copy 64 bytes.  */
+	.p2align 5
+L(bwd_loop_tail):
+	cmpldi 	cr5,r5,63
+	ble	cr5,L(bwd_final_64)
+
+	addi	r4,r4,-64
+	addi	r11,r11,-64
+
+	lxv	32+v0,0(r4)
+	lxv	32+v1,16(r4)
+	lxv	32+v2,32(r4)
+	lxv	32+v3,48(r4)
+
+	stxv	32+v0,0(r11)
+	stxv	32+v1,16(r11)
+	stxv	32+v2,32(r11)
+	stxv	32+v3,48(r11)
+
+	subi	r5,r5,64
+
+/* Copies the last 1-63 bytes.  */
+	.p2align 5
+L(bwd_final_64):
+	/* r8 holds the number of bytes that will be copied with lxv/stxv.  */
+	clrrdi.	r8,r5,4
+	beq	L(tail1_bwd)
+
+	cmpldi	cr5,r5,32
+	lxv	32+v2,-16(r4)
+	blt	cr5,L(tail2_bwd)
+
+	cmpldi	cr6,r5,48
+	lxv	32+v1,-32(r4)
+	blt	cr6,L(tail3_bwd)
+
+	.p2align 5
+	lxv	32+v0,-48(r4)
+	stxv	32+v0,-48(r11)
+L(tail3_bwd):
+	stxv	32+v1,-32(r11)
+L(tail2_bwd):
+	stxv	32+v2,-16(r11)
+	sub	r4,r4,r5
+	sub	r11,r11,r5
+	sub	r5,r5,r8
+	sldi	r6,r5,56
+	lxvl	v4,r4,r6
+	stxvl	v4,r11,r6
+	blr
+
+/* Copy last 16 bytes.  */
+	.p2align 5
+L(tail1_bwd):
+	sub	r4,r4,r5
+	sub	r11,r11,r5
+	sldi	r6,r5,56
+	lxvl	v4,r4,r6
+	stxvl	v4,r11,r6
+	blr
+
+END_GEN_TB (MEMMOVE,TB_TOCLESS)
+libc_hidden_builtin_def (memmove)
+
+/* void bcopy(const void *src [r3], void *dest [r4], size_t n [r5])
+   Implemented in this file to avoid linker create a stub function call
+   in the branch to '_memmove'.  */
+ENTRY_TOCLESS (__bcopy)
+	mr	r6,r3
+	mr	r3,r4
+	mr	r4,r6
+	b	L(_memmove)
+END (__bcopy)
+#ifndef __bcopy
+weak_alias (__bcopy, bcopy)
+#endif
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);
diff --git a/sysdeps/powerpc/powerpc64/power7/memmove.S b/sysdeps/powerpc/powerpc64/power7/memmove.S
index 8366145..f61949d 100644
--- a/sysdeps/powerpc/powerpc64/power7/memmove.S
+++ b/sysdeps/powerpc/powerpc64/power7/memmove.S
@@ -832,4 +832,6 @@ ENTRY_TOCLESS (__bcopy)
 	mr	r4,r6
 	b	L(_memmove)
 END (__bcopy)
+#ifndef __bcopy
 weak_alias (__bcopy, bcopy)
+#endif