powerpc: Optimized strcpy for POWER9

This version uses VSX store vector with length instructions and is
significantly faster on small strings and relatively unaligned large
strings, compared to the POWER8 version. A few examples:

                                        __strcpy_power9  __strcpy_power8
Length   16, alignments in bytes  0/ 0: 2.52454          4.62695
Length  412, alignments in bytes  4/ 0: 11.6             22.9185

1 files changed, 144 insertions, 0 deletions

diff --git a/sysdeps/powerpc/powerpc64/le/power9/strcpy.S b/sysdeps/powerpc/powerpc64/le/power9/strcpy.S
new file mode 100644
index 0000000000..5749228054
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/le/power9/strcpy.S
@@ -0,0 +1,144 @@
+/* Optimized strcpy implementation for PowerPC64/POWER9.
+   Copyright (C) 2020 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>
+
+#ifndef STRCPY
+# define STRCPY strcpy
+#endif
+
+/* Implements the function
+
+   char * [r3] strcpy (char *dest [r3], const char *src [r4])
+
+   The implementation can load bytes past a null terminator, but only
+   up to the next 16B boundary, so it never crosses a page.  */
+
+.machine power9
+ENTRY_TOCLESS (STRCPY, 4)
+	CALL_MCOUNT 2
+
+	/* NULL string optimisation  */
+	lbz	r0,0(r4)
+	stb	r0,0(r3)
+	cmpwi	r0,0
+	beqlr
+
+	addi	r4,r4,1
+	addi	r11,r3,1
+
+	vspltisb v18,0		/* Zeroes in v18  */
+
+	neg	r5,r4
+	rldicl	r9,r5,0,60	/* How many bytes to get source 16B aligned?  */
+
+	/* Get source 16B aligned  */
+	lvx	v0,0,r4
+	lvsr	v1,0,r4
+	vperm	v0,v18,v0,v1
+
+	vcmpequb v6,v0,v18	/* 0xff if byte is NULL, 0x00 otherwise  */
+	vctzlsbb r8,v6		/* Number of trailing zeroes  */
+	addi	r8,r8,1		/* Add null terminator  */
+
+	/* r8 = bytes including null
+	   r9 = bytes to get source 16B aligned
+	   if r8 > r9
+	      no null, copy r9 bytes
+	   else
+	      there is a null, copy r8 bytes and return.  */
+	cmpd	r8,r9
+	bgt	L(no_null)
+
+	sldi	r10,r8,56	/* stxvl wants size in top 8 bits  */
+	stxvl	32+v0,r11,r10	/* Partial store  */
+
+	blr
+
+L(no_null):
+	sldi	r10,r9,56	/* stxvl wants size in top 8 bits  */
+	stxvl	32+v0,r11,r10	/* Partial store  */
+
+	add	r4,r4,r9
+	add	r11,r11,r9
+
+L(loop):
+	lxv	32+v0,0(r4)
+	vcmpequb. v6,v0,v18	/* Any zero bytes?  */
+	bne	cr6,L(tail1)
+
+	lxv	32+v1,16(r4)
+	vcmpequb. v6,v1,v18	/* Any zero bytes?  */
+	bne	cr6,L(tail2)
+
+	lxv	32+v2,32(r4)
+	vcmpequb. v6,v2,v18	/* Any zero bytes?  */
+	bne	cr6,L(tail3)
+
+	lxv	32+v3,48(r4)
+	vcmpequb. v6,v3,v18	/* Any zero bytes?  */
+	bne	cr6,L(tail4)
+
+	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
+
+	b	L(loop)
+
+L(tail1):
+	vctzlsbb r8,v6
+	addi	r8,r8,1
+	sldi	r9,r8,56	/* stxvl wants size in top 8 bits  */
+	stxvl	32+v0,r11,r9
+	blr
+
+L(tail2):
+	stxv	32+v0,0(r11)
+	vctzlsbb r8,v6		/* Number of trailing zeroes  */
+	addi	r8,r8,1		/* Add null terminator  */
+	sldi	r10,r8,56	/* stxvl wants size in top 8 bits  */
+	addi	r11,r11,16
+	stxvl	32+v1,r11,r10	/* Partial store  */
+	blr
+
+L(tail3):
+	stxv	32+v0,0(r11)
+	stxv	32+v1,16(r11)
+	vctzlsbb r8,v6		/* Number of trailing zeroes  */
+	addi	r8,r8,1		/* Add null terminator  */
+	sldi	r10,r8,56	/* stxvl wants size in top 8 bits  */
+	addi	r11,r11,32
+	stxvl	32+v2,r11,r10	/* Partial store  */
+	blr
+
+L(tail4):
+	stxv	32+v0,0(r11)
+	stxv	32+v1,16(r11)
+	stxv	32+v2,32(r11)
+	vctzlsbb r8,v6		/* Number of trailing zeroes  */
+	addi	r8,r8,1		/* Add null terminator  */
+	sldi	r10,r8,56	/* stxvl wants size in top 8 bits  */
+	addi	r11,r11,48
+	stxvl	32+v3,r11,r10	/* Partial store  */
+	blr
+END (STRCPY)
+libc_hidden_builtin_def (strcpy)