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Re: [PATCH] This is optimized strcmp for Power7
- From: Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>
- To: libc-alpha at sourceware dot org
- Date: Tue, 10 Jun 2014 11:13:17 -0300
- Subject: Re: [PATCH] This is optimized strcmp for Power7
- Authentication-results: sourceware.org; auth=none
- References: <1401945190-13296-1-git-send-email-vidya at linux dot vnet dot ibm dot com>
Hi Vidya,
Path looks good, however you forgot to add a ChangeLog. Also one typo below.
Please send the CL entry that will push upstream.
On 05-06-2014 02:13, vidya@linux.vnet.ibm.com wrote:
> From: Vidya Ranganathan <vidya@linux.vnet.ibm.com>
>
> Optimization is achieved on 8 byte aligned strings with double word
> comparison using cmpb instruction. On unaligned strings loop unrolling
> is applied for Power7 gain.
>
> Signed-off-by: Vidya Ranganathan <vidya@linux.vnet.ibm.com>
> ---
> sysdeps/powerpc/powerpc64/multiarch/Makefile | 2 +-
> .../powerpc/powerpc64/multiarch/ifunc-impl-list.c | 7 +
> .../powerpc/powerpc64/multiarch/strcmp-power7.S | 40 +++++
> sysdeps/powerpc/powerpc64/multiarch/strcmp-ppc64.S | 43 +++++
> sysdeps/powerpc/powerpc64/multiarch/strcmp.c | 31 ++++
> sysdeps/powerpc/powerpc64/power7/strcmp.S | 195 +++++++++++++++++++++
> 6 files changed, 317 insertions(+), 1 deletion(-)
> create mode 100644 sysdeps/powerpc/powerpc64/multiarch/strcmp-power7.S
> create mode 100644 sysdeps/powerpc/powerpc64/multiarch/strcmp-ppc64.S
> create mode 100644 sysdeps/powerpc/powerpc64/multiarch/strcmp.c
> create mode 100644 sysdeps/powerpc/powerpc64/power7/strcmp.S
>
> diff --git a/sysdeps/powerpc/powerpc64/multiarch/Makefile b/sysdeps/powerpc/powerpc64/multiarch/Makefile
> index 35020a7..05744e9 100644
> --- a/sysdeps/powerpc/powerpc64/multiarch/Makefile
> +++ b/sysdeps/powerpc/powerpc64/multiarch/Makefile
> @@ -17,7 +17,7 @@ sysdep_routines += memcpy-power7 memcpy-a2 memcpy-power6 memcpy-cell \
> strrchr-power7 strrchr-ppc64 strncat-power7 strncat-ppc64 \
> strspn-power7 strspn-ppc64 strcspn-power7 strcspn-ppc64 \
> strpbrk-power7 strpbrk-ppc64 strncpy-power7 strncpy-ppc64 \
> - stpncpy-power7 stpncpy-ppc64
> + stpncpy-power7 stpncpy-ppc64 strcmp-power7 strcmp-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 d8578fb..b3933a5 100644
> --- a/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
> +++ b/sysdeps/powerpc/powerpc64/multiarch/ifunc-impl-list.c
> @@ -294,5 +294,12 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
> IFUNC_IMPL_ADD (array, i, stpncpy, 1,
> __stpncpy_ppc))
>
> + /* Support sysdeps/powerpc/powerpc64/multiarch/strcmp.c. */
> + IFUNC_IMPL (i, name, strcmp,
> + IFUNC_IMPL_ADD (array, i, strcmp,
> + hwcap & PPC_FEATURE_HAS_VSX,
> + __strcmp_power7)
> + IFUNC_IMPL_ADD (array, i, strcmp, 1,
> + __strcmp_ppc))
> return i;
> }
> diff --git a/sysdeps/powerpc/powerpc64/multiarch/strcmp-power7.S b/sysdeps/powerpc/powerpc64/multiarch/strcmp-power7.S
> new file mode 100644
> index 0000000..790ce8d
> --- /dev/null
> +++ b/sysdeps/powerpc/powerpc64/multiarch/strcmp-power7.S
> @@ -0,0 +1,40 @@
> +/* Optimized strcmp 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(__strcmp_power7) \
> + .align ALIGNARG(alignt); \
> + EALIGN_W_##words; \
> + BODY_LABEL(__strcmp_power7): \
> + cfi_startproc; \
> + LOCALENTRY(__strcmp_power7)
> +
> +#undef END
> +#define END(name) \
> + cfi_endproc; \
> + TRACEBACK(__strcmp_power7) \
> + END_2(__strcmp_power7)
> +
> +#undef libc_hidden_builtin_def
> +#define libc_hidden_builtin_def(name)
> +
> +#include <sysdeps/powerpc/powerpc64/power7/strcmp.S>
> diff --git a/sysdeps/powerpc/powerpc64/multiarch/strcmp-ppc64.S b/sysdeps/powerpc/powerpc64/multiarch/strcmp-ppc64.S
> new file mode 100644
> index 0000000..93d1277
> --- /dev/null
> +++ b/sysdeps/powerpc/powerpc64/multiarch/strcmp-ppc64.S
> @@ -0,0 +1,43 @@
> +/* Default strcmp implementation for PowerPC64.
> + 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>
> +
> +#if defined SHARED && !defined NOT_IN_libc
> +# undef EALIGN
> +# define EALIGN(name, alignt, words) \
> + .section ".text"; \
> + ENTRY_2(__strcmp_ppc) \
> + .align ALIGNARG(alignt); \
> + EALIGN_W_##words; \
> + BODY_LABEL(__strcmp_ppc): \
> + cfi_startproc; \
> + LOCALENTRY(__strcmp_ppc)
> +
> +# undef END
> +# define END(name) \
> + cfi_endproc; \
> + TRACEBACK(__strcmp_ppc) \
> + END_2(__strcmp_ppc)
> +
> +# undef libc_hidden_builtin_def
> +# define libc_hidden_builtin_def(name) \
> + .globl __GI_strcmp; __GI_strcmp = __strcmp_ppc
> +#endif
> +
> +#include <sysdeps/powerpc/powerpc64/strcmp.S>
> diff --git a/sysdeps/powerpc/powerpc64/multiarch/strcmp.c b/sysdeps/powerpc/powerpc64/multiarch/strcmp.c
> new file mode 100644
> index 0000000..2013301
> --- /dev/null
> +++ b/sysdeps/powerpc/powerpc64/multiarch/strcmp.c
> @@ -0,0 +1,31 @@
> +/* Multiple versions of strcmp. 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 (strcmp) __strcmp_ppc attribute_hidden;
> +extern __typeof (strcmp) __strcmp_power7 attribute_hidden;
> +
> +libc_ifunc (strcmp,
> + (hwcap & PPC_FEATURE_HAS_VSX)
> + ? __strcmp_power7
> + : __strcmp_ppc);
> +#endif
> diff --git a/sysdeps/powerpc/powerpc64/power7/strcmp.S b/sysdeps/powerpc/powerpc64/power7/strcmp.S
> new file mode 100644
> index 0000000..f16a9d8
> --- /dev/null
> +++ b/sysdeps/powerpc/powerpc64/power7/strcmp.S
> @@ -0,0 +1,195 @@
> +/* Optimized strcmp implementation for Power7 using 'cmpb' instruction
> + 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/>. */
> +
> +/* The optimization is achieved here through cmpb instruction.
> + 8byte aligned strings are processed with double word comparision
s/comparision/comparison
> + and unaligned strings are handled effectively with loop unrolling
> + technique */
> +
> +#include <sysdep.h>
> +
> +/* int [r3] strcmp (const char *s1 [r3], const char *s2 [r4]) */
> +
> +EALIGN (strcmp, 4, 0)
> + CALL_MCOUNT 2
> +
> + or r9, r3, r4
> + rldicl. r10, r9, 0, 61 /* are s1 and s2 8 byte aligned..? */
> + bne cr0, L(process_unaligned_bytes)
> +
> +/* process input parameters on double word aligned boundary */
> + ld r9, 0(r4) /* load s2 at offset=0 */
> + li r10, 0 /* load mask=0 */
> + cmpb r10, r9, r10 /* compare bytes at s2 with mask */
> + cmpdi cr7, r10, 0 /* is NULL found ..? is end of string HIT */
> + bne cr7, L(process_unaligned_bytes) /* process byte by byte */
> +
> + ld r10, 0(r3) /* load s1 at offset=0 */
> + li r8, 0 /* load mask=0 */
> + cmpb r8, r10, r8 /* compare bytes at s1 with mask */
> + cmpdi cr7, r8, 0 /* is NULL found ..? is end of string HIT */
> + bne cr7, L(process_unaligned_bytes) /* process byte by byte */
> +
> +/*s1 and s2 does not contain NULL now , so compare all 8 bytes in a GO */
> + cmpb r9, r10, r9 /* compare s1 and s2 */
> + cmpdi cr7, r9, -1 /* compare result with 0xFFFFFFFFFFFFFFFF */
> + bne cr7, L(process_unaligned_bytes) /* s1,s2 mismatch found */
> +
> + addi r5, r3, 8 /* save next offset of s2 */
> + addi r11, r4, 8 /* save next offset of s1 */
> + ld r8, 8(r4) /* load s2 at offset=8 */
> + li r9, 0 /* load mask=0 */
> + cmpb r9, r8, r9 /* compare bytes at s2 with mask */
> + cmpdi cr7, r9, 0 /* NULL found ..? */
> + bne cr7, L(processBytes)/* update input and process bytes one by one */
> +
> + mr r9, r4 /* save s2 */
> + li r10, 0 /* load mask=0 */
> +
> + ld r7, 8(r3) /* load s1 at offset=8 */
> + cmpb r6, r7, r10 /* compare bytes at s1 with mask */
> + cmpdi cr7, r6, 0 /* is NULL found */
> + bne cr7, L(processBytes)/* mismatch, so process one by one */
> +
> +L(unrollDword):
> + cmpb r8, r7, r8 /* compare s1 and s2 */
> + cmpdi cr7, r8, -1 /* compare result with 0xFFFFFFFFFFFFFFFF */
> + bne cr7, L(processBytes)/* mismatch with s1 and s2 */
> +
> + addi r5, r3, 16 /* save offset=16 of s1 */
> + addi r4, r9, 16 /* save offset=16 of s2 */
> + ld r8, 16(r9) /* load s2 at offset=16 */
> + cmpb r7, r8, r10 /* compare bytes at s2 with mask */
> + cmpdi cr7, r7, 0 /* NULL found ..? */
> + bne cr7, L(update2processBytes)
> +
> + ld r7, 16(r3) /* load s1 at offset=16 */
> + cmpb r6, r7, r10 /* check s1 for end of string */
> + cmpdi cr7, r6, 0 /* end of s1 ?,then handle byte by byte */
> + bne 7,L(update2processBytes)
> +
> + cmpb r8, r7, r8 /* compare s1 and s2 double words */
> + cmpdi cr7, r8, -1 /* compare results with 0xFFFFFFFFFFFFFFFF */
> + bne cr7,L(update2processBytes)
> +
> + addi r5, r3, 24 /* update s1 to offset=24 */
> + addi r4, r9, 24 /* update s2 to offset=24 */
> +
> + ld r8, 24(r9) /* load s2 */
> + cmpb r7, r8, r10 /* compare s2 for NULL */
> + cmpdi cr7, r7, 0 /* verify if s2 is ending now */
> + bne cr7,L(update2processBytes)
> +
> + ld r7, 24(r3) /* load s1 at offset=24 */
> + cmpb r6, r7, r10 /* verify for NULL */
> + cmpdi cr7, r6, 0 /* is NULL found */
> + bne cr7, L(update2processBytes)
> +
> + cmpb r8, r7, r8 /* compare s1 and s2 */
> + cmpdi cr7, r8, -1 /* are s1 and s2 same ..? */
> + bne cr7, L(update2processBytes)
> +
> + addi r7, r9, 32 /* update s2 to next double word */
> + addi r3, r3, 32 /* update s1 to next double word */
> +
> + ld r8, 32(r9) /* load s2 */
> + mr r4, r7 /* save s2 */
> + cmpb r6, r8, r10 /* compare s2 with NULL */
> + cmpdi cr7, r6, 0 /* end of s2 ..? */
> + bne cr7, L(process_unaligned_bytes)
> +
> + ld r6, 0(r3) /* load and compare s1 for NULL */
> + cmpb r5, r6, r10
> + cmpdi cr7, r5, 0
> + bne cr7, L(process_unaligned_bytes)
> +
> + cmpb r8, r6, r8 /* compare s1 and s2 */
> + cmpdi cr7, r8, -1
> + bne cr7, L(process_unaligned_bytes)
> +
> + addi r5, r3, 8 /* increment s1 and d2 here */
> + addi r11, r9, 40
> +
> + ld r8, 40(r9) /* process s2 now */
> + cmpb r9, r8, r10
> + cmpdi cr7, r9, 0
> + bne cr7, L(processBytes)
> +
> + mr r9, r7
> + ld r7, 8(r3) /* process s1 now */
> + cmpb r6, r7, r10
> + cmpdi cr7, r6, 0
> + beq cr7, L(unrollDword) /* unroll to compare s1 and s2 */
> +
> +L(processBytes):
> + mr r4, r11 /* update input params */
> + mr r3, r5
> +
> + .p2align 4
> +L(process_unaligned_bytes):
> + lbz r9, 0(r3) /* load byte from s1 */
> + lbz r10, 0(r4) /* load byte from s2 */
> + cmpdi cr7, r9, 0 /* compare *s1 with NULL */
> + beq cr7, L(diffOfNULL) /* if *s1 is NULL , return *s1 - *s2 */
> + cmplw cr7, r9, r10 /* compare *s1 and *s2 */
> + bne cr7, L(ComputeDiff) /* branch to compute difference and return */
> +
> + lbz r9, 1(r3) /* load next byte from s1 */
> + lbz r10, 1(r4) /* load next byte from s2 */
> + cmpdi cr7, r9, 0 /* compare *s1 with NULL */
> + beq cr7, L(diffOfNULL) /* if *s1 is NULL , return *s1 - *s2 */
> + cmplw cr7, r9, r10 /* compare *s1 and *s2 */
> + bne cr7, L(ComputeDiff) /* branch to compute difference and return */
> +
> + lbz r9, 2(r3) /* unroll 3rd byte here */
> + lbz r10, 2(r4)
> + cmpdi cr7, r9, 0
> + beq cr7, L(diffOfNULL)
> + cmplw cr7, r9, r10
> + bne 7, L(ComputeDiff)
> +
> + lbz r9, 3(r3) /* unroll 4th byte now */
> + lbz r10, 3(r4)
> + addi r3, r3, 4 /* increment s1 by unroll factor */
> + cmpdi cr7, r9, 0
> + cmplw cr6, 9, r10
> + beq cr7, L(diffOfNULL)
> + addi r4, r4, 4 /* increment s2 by unroll factor */
> + beq cr6, L(process_unaligned_bytes) /* unroll byte processing */
> +
> + .p2align 4
> +L(ComputeDiff):
> + extsw r9, r9
> + subf r10, r10, r9 /* compute s1 - s2 */
> + extsw r3, r10
> + blr /* return */
> +
> + .p2align 4
> +L(diffOfNULL):
> + li r9, 0
> + subf r10, r10, r9 /* compute s1 - s2 */
> + extsw r3, r10 /* sign extend result */
> + blr /* return */
> +
> + .p2align 4
> +L(update2processBytes):
> + mr r3, r5 /* update and proceed */
> + b L(process_unaligned_bytes)
> +
> +END (strcmp)
> +libc_hidden_builtin_def (strcmp)