[PATCH] Fix rawmemchr regression on bulldozer

[OndÅej BÃlka <neleai at seznam dot cz>]

Hi,

We now have a huge performance regression of rawmemchr on bulldozer.
We select __rawmemchr_sse42 which is about five times slower than
alternative __rawmemchr_sse2. Our benchtests can capture asymptotic
speed relatively well and their output on AMD FX(tm)-8150 is below. 


On intel a gap between __rawmemchr_sse42 and __rawmemchr_sse2 is similar
but a bit_Prefer_PMINUB_for_stringop flag selects __rawmemchr_sse2.

After this a  bit_Prefer_PMINUB_for_stringop will no longer be needed
and can be removed by separate cleanup.

OK to commit?

                      simple_rawmemchr  __rawmemchr_sse42 __rawmemchr_sse2
Length   32, alignment  0:  264 108 75
Length   64, alignment  1:  431 193 95
Length   32, alignment  0:  254 138 62
Length   64, alignment  1:  431 193 69
Length   64, alignment  0:  419 193 85
Length   64, alignment  2:  419 177 77
Length   64, alignment  0:  419 177 85
Length   64, alignment  2:  419 164 69
Length  128, alignment  0:  748 298 93
Length   64, alignment  3:  419 164 92
Length  128, alignment  0:  751 298 118
Length   64, alignment  3:  422 180 59
Length  256, alignment  0:  1407  628 131
Length   64, alignment  4:  419 192 72
Length  256, alignment  0:  1409  642 131
Length   64, alignment  4:  422 192 56
Length  512, alignment  0:  2723  1111  183
Length   64, alignment  5:  419 193 59
Length  512, alignment  0:  2725  1111  190
Length   64, alignment  5:  422 193 84
Length 1024, alignment  0:  5356  2026  417
Length   64, alignment  6:  419 192 84
Length 1024, alignment  0:  5359  2026  388



	* sysdeps/x86_64/multiarch/rawmemchr.S: Delete.

---
 sysdeps/x86_64/multiarch/rawmemchr.S | 103 -----------------------------------
 1 file changed, 103 deletions(-)
 delete mode 100644 sysdeps/x86_64/multiarch/rawmemchr.S

diff --git a/sysdeps/x86_64/multiarch/rawmemchr.S b/sysdeps/x86_64/multiarch/rawmemchr.S
deleted file mode 100644
index 50de38f..0000000
--- a/sysdeps/x86_64/multiarch/rawmemchr.S
+++ /dev/null
@@ -1,103 +0,0 @@
-/* Multiple versions of rawmemchr
-   All versions must be listed in ifunc-impl-list.c.
-   Copyright (C) 2009-2013 Free Software Foundation, Inc.
-   Contributed by Ulrich Drepper <drepper@redhat.com>.
-   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>
-#include <init-arch.h>
-
-
-/* Define multiple versions only for the definition in lib.  */
-#ifndef NOT_IN_libc
-	.text
-ENTRY(rawmemchr)
-	.type	rawmemchr, @gnu_indirect_function
-	cmpl	$0, __cpu_features+KIND_OFFSET(%rip)
-	jne	1f
-	call	__init_cpu_features
-1:	testl	$bit_Prefer_PMINUB_for_stringop, __cpu_features+FEATURE_OFFSET+index_Prefer_PMINUB_for_stringop(%rip)
-	jnz	2f
-	testl	$bit_SSE4_2, __cpu_features+CPUID_OFFSET+index_SSE4_2(%rip)
-	jz	2f
-	leaq	__rawmemchr_sse42(%rip), %rax
-	ret
-2:	leaq	__rawmemchr_sse2(%rip), %rax
-	ret
-
-END(rawmemchr)
-strong_alias (rawmemchr, __rawmemchr)
-
-
-	.section .text.sse4.2,"ax",@progbits
-	.align	16
-	.type	__rawmemchr_sse42, @function
-	.globl __rawmemchr_sse42
-	.hidden __rawmemchr_sse42
-__rawmemchr_sse42:
-	cfi_startproc
-	CALL_MCOUNT
-	movd	%esi, %xmm1
-	movq	%rdi, %rcx
-	pxor	%xmm2, %xmm2
-	andq	$~15, %rdi
-	orl	$0xffffffff, %esi
-	pshufb	%xmm2, %xmm1
-	movdqa	(%rdi), %xmm0
-	subq	%rdi, %rcx
-	pcmpeqb	%xmm1, %xmm0
-	shl	%cl, %esi
-	pmovmskb %xmm0, %ecx
-	movl	$16, %eax
-	movl	$16, %edx
-	andl	%esi, %ecx
-	jnz	1f
-
-2:	pcmpestri $0x08, 16(%rdi), %xmm1
-	leaq	16(%rdi), %rdi
-	jnc	2b
-
-	leaq	(%rdi,%rcx), %rax
-	ret
-
-1:	bsfl	%ecx, %eax
-	addq	%rdi, %rax
-	ret
-	cfi_endproc
-	.size	__rawmemchr_sse42, .-__rawmemchr_sse42
-
-
-# undef ENTRY
-# define ENTRY(name) \
-	.type __rawmemchr_sse2, @function; \
-	.align 16; \
-	.globl __rawmemchr_sse2; \
-	.hidden __rawmemchr_sse2; \
-	__rawmemchr_sse2: cfi_startproc; \
-	CALL_MCOUNT
-# undef END
-# define END(name) \
-	cfi_endproc; .size __rawmemchr_sse2, .-__rawmemchr_sse2
-# undef libc_hidden_builtin_def
-/* It doesn't make sense to send libc-internal rawmemchr calls through a PLT.
-   The speedup we get from using SSE4.2 instruction is likely eaten away
-   by the indirect call in the PLT.  */
-# define libc_hidden_builtin_def(name) \
-	.globl __GI___rawmemchr; __GI___rawmemchr = __rawmemchr_sse2
-#endif
-
-#include "../rawmemchr.S"
-- 
1.8.3.2