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Re: [PATCH] PowerPC:strrchr() optimization
- From: Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>
- To: libc-alpha at sourceware dot org
- Date: Mon, 03 Mar 2014 10:31:41 -0300
- Subject: Re: [PATCH] PowerPC:strrchr() optimization
- Authentication-results: sourceware.org; auth=none
- References: <1393824236-8530-1-git-send-email-raji at linux dot vnet dot ibm dot com>
This patch is ok, I'll push it shortly.
On 03-03-2014 02:23, Rajalakshmi Srinivasaraghavan wrote:
> Resending the patch with minor formatting changes.
>
> This patch optimizes strrchr() for ppc64.This uses aligned memory access
> using cmpb instruction and CPU pre-fetch to avoid cache miss for speed improvement.
>
> * sysdeps/powerpc/powerpc64/power7/strrchr.S: New file.
> * sysdeps/powerpc/powerpc64/multiarch/Makefile: Add strrchr multiarch
> implementation.
> * sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c:
> (__libc_ifunc_impl_list): Likewise.
> * sysdeps/powerpc/powerpc64/multiarch/strrchr.c: New file.
> * sysdeps/powerpc/powerpc64/multiarch/strrchr-ppc64.c: New file.
> * sysdeps/powerpc/powerpc64/multiarch/strrchr-power7.S: New file.
> * string/strrchr.c: Define STRRCHR.
>
> Signed-off-by: Rajalakshmi Srinivasaraghavan <raji@linux.vnet.ibm.com>
> ---
> string/strrchr.c | 6 +-
> sysdeps/powerpc/powerpc64/multiarch/Makefile | 3 +-
> .../powerpc/powerpc64/multiarch/ifunc-impl-list.c | 8 +
> .../powerpc/powerpc64/multiarch/strrchr-power7.S | 39 ++++
> .../powerpc/powerpc64/multiarch/strrchr-ppc64.c | 33 +++
> sysdeps/powerpc/powerpc64/multiarch/strrchr.c | 35 +++
> sysdeps/powerpc/powerpc64/power7/strrchr.S | 255 +++++++++++++++++++++
> 7 files changed, 377 insertions(+), 2 deletions(-)
> create mode 100644 sysdeps/powerpc/powerpc64/multiarch/strrchr-power7.S
> create mode 100644 sysdeps/powerpc/powerpc64/multiarch/strrchr-ppc64.c
> create mode 100644 sysdeps/powerpc/powerpc64/multiarch/strrchr.c
> create mode 100644 sysdeps/powerpc/powerpc64/power7/strrchr.S
>
> diff --git a/string/strrchr.c b/string/strrchr.c
> index b5b4bc6..47ff08c 100644
> --- a/string/strrchr.c
> +++ b/string/strrchr.c
> @@ -19,9 +19,13 @@
>
> #undef strrchr
>
> +#ifndef STRRCHR
> +# define STRRCHR strrchr
> +#endif
> +
> /* Find the last occurrence of C in S. */
> char *
> -strrchr (const char *s, int c)
> +STRRCHR (const char *s, int c)
> {
> const char *found, *p;
>
> diff --git a/sysdeps/powerpc/powerpc64/multiarch/Makefile b/sysdeps/powerpc/powerpc64/multiarch/Makefile
> index 3c47316..d09f2e3 100644
> --- a/sysdeps/powerpc/powerpc64/multiarch/Makefile
> +++ b/sysdeps/powerpc/powerpc64/multiarch/Makefile
> @@ -13,7 +13,8 @@ sysdep_routines += memcpy-power7 memcpy-a2 memcpy-power6 memcpy-cell \
> wcschr-power6 wcschr-ppc64 wcsrchr-power7 wcsrchr-power6 \
> wcsrchr-ppc64 wcscpy-power7 wcscpy-power6 wcscpy-ppc64 \
> wordcopy-power7 wordcopy-power6 wordcopy-ppc64 \
> - strcpy-power7 strcpy-ppc64 stpcpy-power7 stpcpy-ppc64
> + strcpy-power7 strcpy-ppc64 stpcpy-power7 stpcpy-ppc64 \
> + strrchr-power7 strrchr-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 6bbdd4e..8789483 100644
> --- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
> +++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
> @@ -238,5 +238,13 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> IFUNC_IMPL_ADD (array, i, wcscpy, 1,
> __wcscpy_ppc))
>
> + /* Support sysdeps/powerpc/powerpc64/multiarch/strrchr.c. */
> + IFUNC_IMPL (i, name, strrchr,
> + IFUNC_IMPL_ADD (array, i, strrchr,
> + hwcap & PPC_FEATURE_HAS_VSX,
> + __strrchr_power7)
> + IFUNC_IMPL_ADD (array, i, strrchr, 1,
> + __strrchr_ppc))
> +
> return i;
> }
> diff --git a/sysdeps/powerpc/powerpc64/multiarch/strrchr-power7.S b/sysdeps/powerpc/powerpc64/multiarch/strrchr-power7.S
> new file mode 100644
> index 0000000..78e15e3
> --- /dev/null
> +++ b/sysdeps/powerpc/powerpc64/multiarch/strrchr-power7.S
> @@ -0,0 +1,39 @@
> +/* Optimized strrchr 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 ENTRY
> +#define ENTRY(name) \
> + .section ".text"; \
> + ENTRY_2(__strrchr_power7) \
> + .align ALIGNARG(2); \
> + BODY_LABEL(__strrchr_power7): \
> + cfi_startproc; \
> + LOCALENTRY(__strrchr_power7)
> +
> +#undef END
> +#define END(name) \
> + cfi_endproc; \
> + TRACEBACK(__strrchr_power7) \
> + END_2(__strrchr_power7)
> +
> +#undef libc_hidden_builtin_def
> +#define libc_hidden_builtin_def(name)
> +
> +#include <sysdeps/powerpc/powerpc64/power7/strrchr.S>
> diff --git a/sysdeps/powerpc/powerpc64/multiarch/strrchr-ppc64.c b/sysdeps/powerpc/powerpc64/multiarch/strrchr-ppc64.c
> new file mode 100644
> index 0000000..5633a9f
> --- /dev/null
> +++ b/sysdeps/powerpc/powerpc64/multiarch/strrchr-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 STRRCHR __strrchr_ppc
> +#undef weak_alias
> +#define weak_alias(name, aliasname) \
> + extern __typeof (__strrchr_ppc) aliasname \
> + __attribute__ ((weak, alias ("__strrchr_ppc")));
> +#if !defined(NOT_IN_libc) && defined(SHARED)
> +# undef libc_hidden_builtin_def
> +# define libc_hidden_builtin_def(name) \
> + __hidden_ver1(__strrchr_ppc, __GI_strrchr, __strrchr_ppc);
> +#endif
> +
> +extern __typeof (strrchr) __strrchr_ppc attribute_hidden;
> +
> +#include <string/strrchr.c>
> diff --git a/sysdeps/powerpc/powerpc64/multiarch/strrchr.c b/sysdeps/powerpc/powerpc64/multiarch/strrchr.c
> new file mode 100644
> index 0000000..046162f
> --- /dev/null
> +++ b/sysdeps/powerpc/powerpc64/multiarch/strrchr.c
> @@ -0,0 +1,35 @@
> +/* Multiple versions of strrchr. 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/>. */
> +
> +/* Define multiple versions only for definition in libc. */
> +#ifndef NOT_IN_libc
> +# include <string.h>
> +# include <shlib-compat.h>
> +# include "init-arch.h"
> +
> +extern __typeof (strrchr) __strrchr_ppc attribute_hidden;
> +extern __typeof (strrchr) __strrchr_power7 attribute_hidden;
> +
> +/* Avoid DWARF definition DIE on ifunc symbol so that GDB can handle
> + ifunc symbol properly. */
> +libc_ifunc (strrchr,
> + (hwcap & PPC_FEATURE_HAS_VSX)
> + ? __strrchr_power7
> + : __strrchr_ppc);
> +weak_alias (strrchr, rindex)
> +#endif
> diff --git a/sysdeps/powerpc/powerpc64/power7/strrchr.S b/sysdeps/powerpc/powerpc64/power7/strrchr.S
> new file mode 100644
> index 0000000..e4a76c8
> --- /dev/null
> +++ b/sysdeps/powerpc/powerpc64/power7/strrchr.S
> @@ -0,0 +1,255 @@
> +/* Optimized strrchr implementation for PowerPC64/POWER7 using cmpb insn.
> + 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>
> +
> +/* int [r3] strrchr (char *s [r3], int c [r4]) */
> + .machine power7
> +ENTRY (strrchr)
> + CALL_MCOUNT 2
> + dcbt 0,r3
> + clrrdi r8,r3,3 /* Align the address to doubleword boundary. */
> + cmpdi cr7,r4,0
> + ld r12,0(r8) /* Load doubleword from memory. */
> + li r9,0 /* used to store last occurence */
> + li r0,0 /* Doubleword with null chars to use
> + with cmpb. */
> +
> + rlwinm r6,r3,3,26,28 /* Calculate padding. */
> +
> + beq cr7,L(null_match)
> +
> + /* Replicate byte to doubleword. */
> + insrdi r4,r4,8,48
> + insrdi r4,r4,16,32
> + insrdi r4,r4,32,0
> +
> + /* r4 is changed now ,if its passed as more chars
> + check for null again */
> + cmpdi cr7,r4,0
> + beq cr7,L(null_match)
> + /* Now r4 has a doubleword of c bytes and r0 has
> + a doubleword of null bytes. */
> +
> + cmpb r10,r12,r4 /* Compare each byte against c byte. */
> + cmpb r11,r12,r0 /* Compare each byte against null byte. */
> +
> + /* Move the doublewords left and right to discard the bits that are
> + not part of the string and bring them back as zeros. */
> +#ifdef __LITTLE_ENDIAN__
> + srd r10,r10,r6
> + srd r11,r11,r6
> + sld r10,r10,r6
> + sld r11,r11,r6
> +#else
> + sld r10,r10,r6
> + sld r11,r11,r6
> + srd r10,r10,r6
> + srd r11,r11,r6
> +#endif
> + or r5,r10,r11 /* OR the results to speed things up. */
> + cmpdi cr7,r5,0 /* If r5 == 0, no c or null bytes
> + have been found. */
> + bne cr7,L(done)
> +
> +L(align):
> + mtcrf 0x01,r8
> +
> + /* Are we now aligned to a doubleword boundary? If so, skip to
> + the main loop. Otherwise, go through the alignment code. */
> +
> + bt 28,L(loop)
> +
> + /* Handle WORD2 of pair. */
> + ldu r12,8(r8)
> + cmpb r10,r12,r4
> + cmpb r11,r12,r0
> + or r5,r10,r11
> + cmpdi cr7,r5,0
> + bne cr7,L(done)
> + b L(loop) /* We branch here (rather than falling through)
> + to skip the nops due to heavy alignment
> + of the loop below. */
> + .p2align 5
> +L(loop):
> + /* Load two doublewords, compare and merge in a
> + single register for speed. This is an attempt
> + to speed up the null-checking process for bigger strings. */
> + ld r12,8(r8)
> + ldu r7,16(r8)
> + cmpb r10,r12,r4
> + cmpb r11,r12,r0
> + cmpb r6,r7,r4
> + cmpb r7,r7,r0
> + or r12,r10,r11
> + or r5,r6,r7
> + or r5,r12,r5
> + cmpdi cr7,r5,0
> + beq cr7,L(loop)
> +
> + /* OK, one (or both) of the doublewords contains a c/null byte. Check
> + the first doubleword and decrement the address in case the first
> + doubleword really contains a c/null byte. */
> + cmpdi cr6,r12,0
> + addi r8,r8,-8
> + bne cr6,L(done)
> +
> + /* The c/null byte must be in the second doubleword. Adjust the
> + address again and move the result of cmpb to r10 so we can calculate
> + the pointer. */
> +
> + mr r10,r6
> + mr r11,r7
> + addi r8,r8,8
> +
> + /* r10/r11 have the output of the cmpb instructions, that is,
> + 0xff in the same position as the c/null byte in the original
> + doubleword from the string. Use that to calculate the pointer. */
> +
> +L(done):
> + /* if there are more than one 0xff in r11, find the first pos of ff
> + in r11 and fill r10 with 0 from that position */
> + cmpdi cr7,r11,0
> + beq cr7,L(no_null)
> +#ifdef __LITTLE_ENDIAN__
> + addi r3,r11,-1
> + andc r3,r3,r11
> + popcntd r0,r3
> +#else
> + cntlzd r0,r11
> +#endif
> + subfic r0,r0,63
> + li r6,-1
> +#ifdef __LITTLE_ENDIAN__
> + srd r0,r6,r0
> +#else
> + sld r0,r6,r0
> +#endif
> + and r10,r0,r10
> +L(no_null):
> +#ifdef __LITTLE_ENDIAN__
> + cntlzd r0,r10 /* Count leading zeros before c matches. */
> + addi r3,r10,-1
> + andc r3,r3,r10
> + addi r10,r11,-1
> + andc r10,r10,r11
> + cmpld cr7,r3,r10
> + bgt cr7,L(no_match)
> +#else
> + addi r3,r10,-1 /* Count trailing zeros before c matches. */
> + andc r3,r3,r10
> + popcntd r0,r3
> + cmpld cr7,r11,r10
> + bgt cr7,L(no_match)
> +#endif
> + srdi r0,r0,3 /* Convert trailing zeros to bytes. */
> + subfic r0,r0,7
> + add r9,r8,r0 /* Return address of the matching c byte
> + or null in case c was not found. */
> + li r0,0
> + cmpdi cr7,r11,0 /* If r11 == 0, no null's have been found. */
> + beq cr7,L(align)
> +
> + .align 4
> +L(no_match):
> + mr r3,r9
> + blr
> +
> +/* We are here because strrchr was called with a null byte. */
> + .align 4
> +L(null_match):
> + /* r0 has a doubleword of null bytes. */
> +
> + cmpb r5,r12,r0 /* Compare each byte against null bytes. */
> +
> + /* Move the doublewords left and right to discard the bits that are
> + not part of the string and bring them back as zeros. */
> +#ifdef __LITTLE_ENDIAN__
> + srd r5,r5,r6
> + sld r5,r5,r6
> +#else
> + sld r5,r5,r6
> + srd r5,r5,r6
> +#endif
> + cmpdi cr7,r5,0 /* If r10 == 0, no c or null bytes
> + have been found. */
> + bne cr7,L(done_null)
> +
> + mtcrf 0x01,r8
> +
> + /* Are we now aligned to a quadword boundary? If so, skip to
> + the main loop. Otherwise, go through the alignment code. */
> +
> + bt 28,L(loop_null)
> +
> + /* Handle WORD2 of pair. */
> + ldu r12,8(r8)
> + cmpb r5,r12,r0
> + cmpdi cr7,r5,0
> + bne cr7,L(done_null)
> + b L(loop_null) /* We branch here (rather than falling through)
> + to skip the nops due to heavy alignment
> + of the loop below. */
> +
> + /* Main loop to look for the end of the string. Since it's a
> + small loop (< 8 instructions), align it to 32-bytes. */
> + .p2align 5
> +L(loop_null):
> + /* Load two doublewords, compare and merge in a
> + single register for speed. This is an attempt
> + to speed up the null-checking process for bigger strings. */
> + ld r12,8(r8)
> + ldu r11,16(r8)
> + cmpb r5,r12,r0
> + cmpb r10,r11,r0
> + or r6,r5,r10
> + cmpdi cr7,r6,0
> + beq cr7,L(loop_null)
> +
> + /* OK, one (or both) of the doublewords contains a null byte. Check
> + the first doubleword and decrement the address in case the first
> + doubleword really contains a null byte. */
> +
> + cmpdi cr6,r5,0
> + addi r8,r8,-8
> + bne cr6,L(done_null)
> +
> + /* The null byte must be in the second doubleword. Adjust the address
> + again and move the result of cmpb to r10 so we can calculate the
> + pointer. */
> +
> + mr r5,r10
> + addi r8,r8,8
> +
> + /* r5 has the output of the cmpb instruction, that is, it contains
> + 0xff in the same position as the null byte in the original
> + doubleword from the string. Use that to calculate the pointer. */
> +L(done_null):
> +#ifdef __LITTLE_ENDIAN__
> + addi r0,r5,-1
> + andc r0,r0,r5
> + popcntd r0,r0
> +#else
> + cntlzd r0,r5 /* Count leading zeros before the match. */
> +#endif
> + srdi r0,r0,3 /* Convert trailing zeros to bytes. */
> + add r3,r8,r0 /* Return address of the matching null byte. */
> + blr
> +END (strrchr)
> +weak_alias (strrchr, rindex)
> +libc_hidden_builtin_def (strrchr)