[PATCH] Multiarch optimization for strspn on POWERPC

[R Vidya <vidya at linux dot vnet dot ibm dot com>]

>From d6530ad0858d0feab7f0481a156baa95fd887f6b Mon Sep 17 00:00:00 2001
From: Vidya Ranganathan <vidya@linux.vnet.ibm.com>
Date: Tue, 4 Mar 2014 05:14:42 -0500
Subject: [PATCH] Multiarch optimization for strspn() on PowerPC. I have
 attached the benchtest output to show the performance improvement.

The optimization is achieved by following techniques:
   > hashing of needle.
   > hashing avoids scanning of duplicate entries in needle across the string.
   > initializing the hash table with Vector instructions (VSX) by quadword access.
   > unrolling when scanning for character in string across hash table.

ChangeLog:
2014-03-04  Vidya Ranganathan  <vidya@linux.vnet.ibm.com>

	* sysdeps/powerpc/powerpc64/power7/strspn.S: New file: Optimization.
	* sysdeps/powerpc/powerpc64/multiarch/strspn.c: New file:
	multiarch strspn for PPC64.
	* sysdeps/powerpc/powerpc64/multiarch/strspn-ppc64.c: New file
	* sysdeps/powerpc/powerpc64/multiarch/strspn-power7.S: New file
	* sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c:
	(__libc_ifunc_impl_list): Likewise.
	* sysdeps/powerpc/powerpc64/multiarch/Makefile: Add strspn
	multiarch optimizations
	* string/strspn.c (strspn): Using macro to redefine symbol name.

Signed-off-by: Vidya Ranganathan <vidya@linux.vnet.ibm.com>
---
 string/strspn.c                                    |   5 +-
 sysdeps/powerpc/powerpc64/multiarch/Makefile       |   2 +-
 .../powerpc/powerpc64/multiarch/ifunc-impl-list.c  |   8 ++
 .../powerpc/powerpc64/multiarch/strspn-power7.S    |  40 ++++++
 sysdeps/powerpc/powerpc64/multiarch/strspn-ppc64.c |  33 +++++
 sysdeps/powerpc/powerpc64/multiarch/strspn.c       |  31 +++++
 sysdeps/powerpc/powerpc64/power7/strspn.S          | 149 +++++++++++++++++++++
 7 files changed, 266 insertions(+), 2 deletions(-)
 create mode 100644 sysdeps/powerpc/powerpc64/multiarch/strspn-power7.S
 create mode 100644 sysdeps/powerpc/powerpc64/multiarch/strspn-ppc64.c
 create mode 100644 sysdeps/powerpc/powerpc64/multiarch/strspn.c
 create mode 100644 sysdeps/powerpc/powerpc64/power7/strspn.S

diff --git a/string/strspn.c b/string/strspn.c
index 37e8161..557eec5 100644
--- a/string/strspn.c
+++ b/string/strspn.c
@@ -18,11 +18,14 @@
 #include <string.h>
 
 #undef strspn
+#ifndef STRSPN
+#define STRSPN strspn
+#endif
 
 /* Return the length of the maximum initial segment
    of S which contains only characters in ACCEPT.  */
 size_t
-strspn (s, accept)
+STRSPN (s, accept)
      const char *s;
      const char *accept;
 {
diff --git a/sysdeps/powerpc/powerpc64/multiarch/Makefile b/sysdeps/powerpc/powerpc64/multiarch/Makefile
index d09f2e3..9821101 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/Makefile
+++ b/sysdeps/powerpc/powerpc64/multiarch/Makefile
@@ -14,7 +14,7 @@ sysdep_routines += memcpy-power7 memcpy-a2 memcpy-power6 memcpy-cell \
 		   wcsrchr-ppc64 wcscpy-power7 wcscpy-power6 wcscpy-ppc64 \
 		   wordcopy-power7 wordcopy-power6 wordcopy-ppc64 \
 		   strcpy-power7 strcpy-ppc64 stpcpy-power7 stpcpy-ppc64 \
-		   strrchr-power7 strrchr-ppc64
+		   strrchr-power7 strrchr-ppc64 strspn-power7 strspn-ppc64
 
 CFLAGS-strncase-power7.c += -mcpu=power7 -funroll-loops
 CFLAGS-strncase_l-power7.c += -mcpu=power7 -funroll-loops
diff --git a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
index 8789483..7cf60f6 100644
--- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
+++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
@@ -246,5 +246,13 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 	      IFUNC_IMPL_ADD (array, i, strrchr, 1,
 			      __strrchr_ppc))
 
+  /* Support sysdeps/powerpc/powerpc64/multiarch/strspn.c.  */
+  IFUNC_IMPL (i, name, strspn,
+	      IFUNC_IMPL_ADD (array, i, strspn,
+			      hwcap & PPC_FEATURE_HAS_VSX,
+			      __strspn_power7)
+	      IFUNC_IMPL_ADD (array, i, strspn, 1,
+			      __strspn_ppc))
+
   return i;
 }
diff --git a/sysdeps/powerpc/powerpc64/multiarch/strspn-power7.S b/sysdeps/powerpc/powerpc64/multiarch/strspn-power7.S
new file mode 100644
index 0000000..889dfee
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/multiarch/strspn-power7.S
@@ -0,0 +1,40 @@
+/* Optimized strspn implementation for POWER7.
+   Copyright (C) 2014 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>
+
+#undef EALIGN
+#define EALIGN(name, alignt, words)				\
+  .section ".text";						\
+  ENTRY_2(__strspn_power7)					\
+  .align ALIGNARG(alignt);					\
+  EALIGN_W_##words;						\
+  BODY_LABEL(__strspn_power7):					\
+  cfi_startproc;						\
+  LOCALENTRY(__strspn_power7)
+
+#undef END
+#define END(name)						\
+  cfi_endproc;							\
+  TRACEBACK(__strspn_power7)					\
+  END_2(__strspn_power7)
+
+#undef libc_hidden_builtin_def
+#define libc_hidden_builtin_def(name)
+
+#include <sysdeps/powerpc/powerpc64/power7/strspn.S>
diff --git a/sysdeps/powerpc/powerpc64/multiarch/strspn-ppc64.c b/sysdeps/powerpc/powerpc64/multiarch/strspn-ppc64.c
new file mode 100644
index 0000000..d543772
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/multiarch/strspn-ppc64.c
@@ -0,0 +1,33 @@
+/* Copyright (C) 2014 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 <string.h>
+
+#define STRSPN __strspn_ppc
+#undef weak_alias
+#define weak_alias(name, aliasname) \
+  extern __typeof (__strspn_ppc) aliasname \
+    __attribute__ ((weak, alias ("__strspn_ppc")));
+#if !defined(NOT_IN_libc) && defined(SHARED)
+# undef libc_hidden_builtin_def
+# define libc_hidden_builtin_def(name) \
+  __hidden_ver1(__strspn_ppc, __GI_strspn, __strspn_ppc);
+#endif
+
+extern __typeof (strspn) __strspn_ppc attribute_hidden;
+
+#include <string/strspn.c>
diff --git a/sysdeps/powerpc/powerpc64/multiarch/strspn.c b/sysdeps/powerpc/powerpc64/multiarch/strspn.c
new file mode 100644
index 0000000..44945f3
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/multiarch/strspn.c
@@ -0,0 +1,31 @@
+/* Multiple versions of strspn. PowerPC64 version.
+   Copyright (C) 2014 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/>.  */
+
+#if defined SHARED && !defined NOT_IN_libc
+# include <string.h>
+# include <shlib-compat.h>
+# include "init-arch.h"
+
+extern __typeof (strspn) __strspn_ppc attribute_hidden;
+extern __typeof (strspn) __strspn_power7 attribute_hidden;
+
+libc_ifunc (strspn,
+            (hwcap & PPC_FEATURE_HAS_VSX)
+            ? __strspn_power7
+            : __strspn_ppc);
+#endif
diff --git a/sysdeps/powerpc/powerpc64/power7/strspn.S b/sysdeps/powerpc/powerpc64/power7/strspn.S
new file mode 100644
index 0000000..a891768
--- /dev/null
+++ b/sysdeps/powerpc/powerpc64/power7/strspn.S
@@ -0,0 +1,149 @@
+/* Optimized strspn implementation for PowerPC64/POWER7.
+
+   Copyright (C) 2014 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/>.  */
+
+/* size_t [r3] strspn (const char *string [r3],
+                       const char *needleAccept [r4]  */
+
+/* Performance gains are grabbed through following techniques:
+
+   > hashing of needle.
+   > hashing avoids scanning of duplicate entries in needle across the string.
+   > initializing the hash table with Vector instructions by quadword access.
+   > unrolling when scanning for character in string across hash table.  */
+
+/* Algorithm is as below:
+   1. A empty hash table/dictionary is created comprising of 256 ascii character set
+   2. When hash entry is found in needle , the hash index is initialized to 1
+   3. The string is scanned until end and for every character, its corresponding
+      hash index is compared.
+   4. initial length of string (count) until first hit of accept needle to be found
+      is set to 0
+   4. If hash index is set to 1 for the index of string, count is returned.
+   5. Otherwise count is incremented and scanning continues until end of string.
+*/
+
+#include <sysdep.h>
+
+#undef strspn
+
+	.machine  power7
+EALIGN(strspn, 4, 0)
+	CALL_MCOUNT 2
+
+	lbz r10, 0(r4)		/* load r10 with needle (r4) */
+	addi r9, r1, -272	/* r9 is a hash of 272 bytes */
+
+	li r5, 16		/* set r5 = 16 as offset  */
+	li r6, 32		/* set r6 = 32 as offset  */
+	li r8, 48		/* set r8 = 48 as offset  */
+
+/*Iniatliaze hash table with Zeroes in double indexed quadword accesses */
+	xxlxor v0, v0, v0	/* prepare for initializing hash */
+
+	stxvd2x v0, r0, r9	/* initialize 1st quadword */
+	stxvd2x v0, r9, r5
+	stxvd2x v0, r9, r6
+	stxvd2x v0, r9, r8	/* initialize 4th quadword */
+
+	addi r11, r9, 64	/* r11 is index to hash */
+
+	stxvd2x v0, r0, r11	/* initialize 5th quadword */
+	stxvd2x v0, r11, r5
+	stxvd2x v0, r11, r6
+	stxvd2x v0, r11, r8	/* initialize 8th quadword */
+
+	addi r11, r9, 128	/* r11 is index to hash */
+
+	stxvd2x v0, r0, r11	/* initialize 9th quadword */
+	stxvd2x v0, r11, r5
+	stxvd2x v0, r11, r6
+	stxvd2x v0, r11, r8	/* initialize 12th quadword */
+
+	addi r11, r9, 192	/* r11 is index to hash */
+
+	stxvd2x v0, r0, r11	/* initialize 13th quadword */
+	stxvd2x v0, r11, r5
+	stxvd2x v0, r11, r6
+	stxvd2x v0, r11, r8	/* initialize 16th quadword */
+
+	li r8, 1		/* r8=1, marker into hash if found in needle */
+
+	cmpdi cr7, r10, 0	/* accept needle is NULL */
+	beq cr7, L(skipHashing)	/* if needle is NULL, skip hashing */
+
+	.p2align 4		/* align section to 16 byte boundary */
+L(hashing):
+	stbx r8, r9, r10	/* update hash with marker for the pivot of the needle */
+	lbzu r10, 1(r4)		/* load needle into r10 and update to next */
+	cmpdi cr7, r10, 0	/* if needle is has reached NULL, continue */
+	bne cr7, L(hashing)	/* loop to hash the needle */
+
+L(skipHashing):
+	li r10, 0		/* load counter = 0 */
+	b L(beginScan)
+
+	.p2align 4		/* align section to 16 byte boundary */
+L(scanUnroll):
+	lbzx r8, r9, r8		/* load r8 with hash value at index */
+	cmpwi cr7, r8, 0	/* if we hit marker in hash, we have found accept needle */
+	beq cr7, L(ret1stIndex)	/* we have hit accept needle, return the count */
+
+	lbz r8, 1(r3)		/* load string[1] into r8 */
+	addi r10, r10, 4	/* increment counter */
+	lbzx r8, r9, r8		/* load r8 with hash value at index */
+	cmpwi cr7, r8, 0	/* if we hit marker in hash, we have found accept needle */
+	beq cr7, L(ret2ndIndex)	/* we have hit accept needle, return the count */
+
+	lbz r8, 2(r3)		/* load string[2] into r8 */
+	lbzx r8, r9, r8		/* load r8 with hash value at index */
+	cmpwi cr7, r8, 0	/* if we hit marker in hash, we have found accept needle */
+	beq cr7, L(ret3rdIndex)	/* we have hit accept needle, return the count */
+
+	lbz r8, 3(r3)		/* load string[3] into r8 */
+	lbzx r8, r9, r8		/* load r8 with hash value at index */
+	addi r3, r3, 4		/* unroll factor , increment string by 4 */
+	cmpwi cr7, r8, 0	/* if we hit marker in hash, we have found accept needle */
+	beq cr7,L(ret4thIndex)	/* we have hit accept needle, return the count */
+
+L(beginScan):
+	lbz r8, 0(r3)		/* load string[0] into r8 */
+	addi r6, r10, 1		/* place holder for counter + 1 */
+	addi r5, r10, 2		/* place holder for counter + 2 */
+	addi r4, r10, 3		/* place holder for counter + 3 */
+	cmpdi cr7, r8, 0	/* if we hit marker in hash, we have found accept needle */
+	bne cr7, L(scanUnroll)	/* continue scanning */
+
+L(ret1stIndex):
+	mr r3, r10		/* update r3 for return */
+	blr			/* return */
+
+L(ret2ndIndex):
+	mr r3, r6		/* update r3 for return */
+	blr			/* return */
+
+L(ret3rdIndex):
+	mr r3, r5		/* update r3 for return */
+	blr			/* return */
+
+L(ret4thIndex):
+	mr r3, r4		/* update r3 for return */
+	blr			/* done */
+
+END(strspn)
+libc_hidden_builtin_def (strspn)
-- 
1.8.3.1

Attachment: bench-strspn.ppc64.out
Description: Text document

Attachment: bench-strspn.ppc64le.out
Description: Text document