[PATCHv2] powerpc64le: Optimize memcpy for POWER10

Message ID 20210430002458.59571-1-tuliom@linux.ibm.com
State New
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  • [PATCHv2] powerpc64le: Optimize memcpy for POWER10
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Commit Message

Martin Sebor via Libc-alpha April 30, 2021, 12:24 a.m.
Changes since v1:

 - Replaced the usage of subic with subi, when possible.
 - Reduced a dependency on r10 in copy_ge_256 code.
 - Stopped building this file on big endian.

------8<------

This implementation is based on __memcpy_power8_cached and integrates
suggestions from Anton Blanchard.
It benefits from loads and stores with length for short lengths and for
tail code, simplifying the code.

All unaligned memory accesses use instructions that do not generate
alignment interrupts on POWER10, making it safe to use on
caching-inhibited memory.

The main loop has also been modified in order to increase instruction
throughput by reducing the dependency on updates from previous iterations.

On average, this implementation provides around 30% improvement when
compared to __memcpy_power7 and 10% improvement in comparison to
__memcpy_power8_cached.
---
 sysdeps/powerpc/powerpc64/le/power10/memcpy.S | 198 ++++++++++++++++++
 sysdeps/powerpc/powerpc64/multiarch/Makefile  |   3 +-
 .../powerpc64/multiarch/ifunc-impl-list.c     |   6 +
 .../powerpc64/multiarch/memcpy-power10.S      |  26 +++
 sysdeps/powerpc/powerpc64/multiarch/memcpy.c  |   7 +
 5 files changed, 239 insertions(+), 1 deletion(-)
 create mode 100644 sysdeps/powerpc/powerpc64/le/power10/memcpy.S
 create mode 100644 sysdeps/powerpc/powerpc64/multiarch/memcpy-power10.S

-- 
2.30.2

Comments

Martin Sebor via Libc-alpha April 30, 2021, 12:56 p.m. | #1
Tested the patch with --with-cpu=power10 and with and without
--disable-multi-arch on top of the master (commit e046d73e5f2f) with no
regression from upstream.


LGTM, and thanks for the patch Tulio.


o/
Raoni
Martin Sebor via Libc-alpha April 30, 2021, 9:19 p.m. | #2
Raoni Fassina Firmino via Libc-alpha <libc-alpha@sourceware.org> writes:

> Tested the patch with --with-cpu=power10 and with and without

> --disable-multi-arch on top of the master (commit e046d73e5f2f) with no

> regression from upstream.

>

>

> LGTM, and thanks for the patch Tulio.


Thank you!

Pushed as e941e0ae80626b7661c1db8953a673cafd3b8b19.

-- 
Tulio Magno

Patch

diff --git a/sysdeps/powerpc/powerpc64/le/power10/memcpy.S b/sysdeps/powerpc/powerpc64/le/power10/memcpy.S
new file mode 100644
index 0000000000..ad1414db4a
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/le/power10/memcpy.S
@@ -0,0 +1,198 @@ 
+/* Optimized memcpy 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <sysdep.h>
+
+
+#ifndef MEMCPY
+# define MEMCPY memcpy
+#endif
+
+/* __ptr_t [r3] memcpy (__ptr_t dst [r3], __ptr_t src [r4], size_t len [r5]);
+	   Returns 'dst'.  */
+
+	.machine power9
+ENTRY_TOCLESS (MEMCPY, 5)
+	CALL_MCOUNT 3
+
+	/* Copy up to 16 bytes.  */
+	sldi	r6,r5,56	/* Prepare [l|st]xvl counter.  */
+	lxvl	v10,r4,r6
+	stxvl	v10,r3,r6
+	subic.	r6,r5,16	/* Return if len <= 16.  */
+	blelr
+
+	/* If len >= 256, assume nothing got copied before and copy
+	   again.  This might cause issues with overlapped memory, but memcpy
+	   is not expected to treat overlapped memory.  */
+	cmpdi	r5,256
+	bge	L(copy_ge_256)
+	/* 16 < len < 256 and the first 16 bytes have already been copied.  */
+	addi	r10,r3,16	/* Keep r3 intact as return value.  */
+	addi	r4,r4,16
+	subi	r5,r5,16
+	b	L(copy_lt_256)	/* Avoid the main loop if len < 256.  */
+
+	.p2align 5
+L(copy_ge_256):
+	mr	r10,r3		/* Keep r3 intact as return value.  */
+	/* Align dst to 16 bytes.  */
+	andi.	r9,r10,0xf
+	beq	L(dst_is_align_16)
+	lxv	v10,0(r4)
+	subfic	r12,r9,16
+	subf	r5,r12,r5
+	add	r4,r4,r12
+	stxv	v10,0(r3)
+	add	r10,r3,r12
+
+L(dst_is_align_16):
+	srdi	r9,r5,7		/* Divide by 128.  */
+	mtctr	r9
+	addi	r6,r4,64
+	addi	r7,r10,64
+
+
+	/* Main loop, copy 128 bytes per iteration.
+	   Use r6=src+64 and r7=dest+64 in order to reduce the dependency on
+	   r4 and r10.  */
+	.p2align 5
+L(copy_128):
+
+	lxv	v10, 0(r4)
+	lxv	v11, 16(r4)
+	lxv	v12, 32(r4)
+	lxv	v13, 48(r4)
+
+	addi	r4,r4,128
+
+	stxv	v10, 0(r10)
+	stxv	v11, 16(r10)
+	stxv	v12, 32(r10)
+	stxv	v13, 48(r10)
+
+	addi	r10,r10,128
+
+	lxv	v10, 0(r6)
+	lxv	v11, 16(r6)
+	lxv	v12, 32(r6)
+	lxv	v13, 48(r6)
+
+	addi	r6,r6,128
+
+	stxv	v10, 0(r7)
+	stxv	v11, 16(r7)
+	stxv	v12, 32(r7)
+	stxv	v13, 48(r7)
+
+	addi	r7,r7,128
+
+	bdnz	L(copy_128)
+
+	clrldi.	r5,r5,64-7	/* Have we copied everything?  */
+	beqlr
+
+	.p2align 5
+L(copy_lt_256):
+	cmpdi	r5,16
+	ble	L(copy_le_16)
+	srdi.	r9,r5,5		/* Divide by 32.  */
+	beq	L(copy_lt_32)
+	mtctr	r9
+	/* Use r6=src+32, r7=dest+32, r8=src+64, r9=dest+64 in order to reduce
+	   the dependency on r4 and r10.  */
+	addi	r6,r4,32
+	addi	r7,r10,32
+	addi	r8,r4,64
+	addi	r9,r10,64
+
+	.p2align 5
+	/* Copy 32 bytes at a time, unaligned.
+	   The loop is unrolled 3 times in order to reduce the dependency on
+	   r4 and r10, copying up-to 96 bytes per iteration.  */
+L(copy_32):
+	lxv	v10, 0(r4)
+	lxv	v11, 16(r4)
+	stxv	v10, 0(r10)
+	stxv	v11, 16(r10)
+	bdz	L(end_copy_32a)
+	addi	r4,r4,96
+	addi	r10,r10,96
+
+	lxv	v10, 0(r6)
+	lxv	v11, 16(r6)
+	addi	r6,r6,96
+	stxv	v10, 0(r7)
+	stxv	v11, 16(r7)
+	bdz	L(end_copy_32b)
+	addi	r7,r7,96
+
+	lxv	v12, 0(r8)
+	lxv	v13, 16(r8)
+	addi	r8,r8,96
+	stxv	v12, 0(r9)
+	stxv	v13, 16(r9)
+	addi	r9,r9,96
+	bdnz	L(copy_32)
+
+	clrldi.	r5,r5,64-5	/* Have we copied everything?  */
+	beqlr
+	cmpdi	r5,16
+	ble	L(copy_le_16)
+	b	L(copy_lt_32)
+
+	.p2align 5
+L(end_copy_32a):
+	clrldi.	r5,r5,64-5	/* Have we copied everything?  */
+	beqlr
+	/* 32 bytes have been copied since the last update of r4 and r10.  */
+	addi	r4,r4,32
+	addi	r10,r10,32
+	cmpdi	r5,16
+	ble	L(copy_le_16)
+	b	L(copy_lt_32)
+
+	.p2align 5
+L(end_copy_32b):
+	clrldi.	r5,r5,64-5	/* Have we copied everything?  */
+	beqlr
+	/* The last iteration of the loop copied 64 bytes.  Update r4 and r10
+	   accordingly.  */
+	addi	r4,r4,-32
+	addi	r10,r10,-32
+	cmpdi	r5,16
+	ble	L(copy_le_16)
+
+	.p2align 5
+L(copy_lt_32):
+	lxv	v10, 0(r4)
+	stxv	v10, 0(r10)
+	addi	r4,r4,16
+	addi	r10,r10,16
+	subi	r5,r5,16
+
+	.p2align 5
+L(copy_le_16):
+	sldi	r6,r5,56
+	lxvl	v10,r4,r6
+	stxvl	v10,r10,r6
+	blr
+
+
+END_GEN_TB (MEMCPY,TB_TOCLESS)
+libc_hidden_builtin_def (memcpy)
diff --git a/sysdeps/powerpc/powerpc64/multiarch/Makefile b/sysdeps/powerpc/powerpc64/multiarch/Makefile
index cd5f46576b..040c53839b 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/Makefile
+++ b/sysdeps/powerpc/powerpc64/multiarch/Makefile
@@ -33,7 +33,8 @@  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 += memcpy-power10 \
+		   strcmp-power9 strncmp-power9 strcpy-power9 stpcpy-power9 \
 		   rawmemchr-power9 strlen-power9 strncpy-power9 stpncpy-power9 \
 		   memmove-power10 strlen-power10
 endif
diff --git a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
index d00bcc8178..1ab56bb2c9 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
@@ -51,6 +51,12 @@  __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 #ifdef SHARED
   /* Support sysdeps/powerpc/powerpc64/multiarch/memcpy.c.  */
   IFUNC_IMPL (i, name, memcpy,
+#ifdef __LITTLE_ENDIAN__
+	      IFUNC_IMPL_ADD (array, i, memcpy,
+			      hwcap2 & PPC_FEATURE2_ARCH_3_1
+			      && hwcap & PPC_FEATURE_HAS_VSX,
+			      __memcpy_power10)
+#endif
 	      IFUNC_IMPL_ADD (array, i, memcpy, hwcap2 & PPC_FEATURE2_ARCH_2_07,
 			      __memcpy_power8_cached)
 	      IFUNC_IMPL_ADD (array, i, memcpy, hwcap & PPC_FEATURE_HAS_VSX,
diff --git a/sysdeps/powerpc/powerpc64/multiarch/memcpy-power10.S b/sysdeps/powerpc/powerpc64/multiarch/memcpy-power10.S
new file mode 100644
index 0000000000..70e0fc3ed6
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/multiarch/memcpy-power10.S
@@ -0,0 +1,26 @@ 
+/* Optimized memcpy 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/>.  */
+
+#if defined __LITTLE_ENDIAN__ && IS_IN (libc)
+#define MEMCPY __memcpy_power10
+
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(name)
+
+#include <sysdeps/powerpc/powerpc64/le/power10/memcpy.S>
+#endif
diff --git a/sysdeps/powerpc/powerpc64/multiarch/memcpy.c b/sysdeps/powerpc/powerpc64/multiarch/memcpy.c
index 5733192932..53ab32ef26 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/memcpy.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/memcpy.c
@@ -36,8 +36,15 @@  extern __typeof (__redirect_memcpy) __memcpy_power6 attribute_hidden;
 extern __typeof (__redirect_memcpy) __memcpy_a2 attribute_hidden;
 extern __typeof (__redirect_memcpy) __memcpy_power7 attribute_hidden;
 extern __typeof (__redirect_memcpy) __memcpy_power8_cached attribute_hidden;
+# if defined __LITTLE_ENDIAN__
+extern __typeof (__redirect_memcpy) __memcpy_power10 attribute_hidden;
+# endif
 
 libc_ifunc (__libc_memcpy,
+# if defined __LITTLE_ENDIAN__
+	    (hwcap2 & PPC_FEATURE2_ARCH_3_1 && hwcap & PPC_FEATURE_HAS_VSX)
+	    ? __memcpy_power10 :
+# endif
 	    ((hwcap2 & PPC_FEATURE2_ARCH_2_07) && use_cached_memopt)
 	    ? __memcpy_power8_cached :
 	      (hwcap & PPC_FEATURE_HAS_VSX)