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x86-64: New memchr implementation.

Message ID 20150607205244.GA6997@domone
State New
Headers show

Commit Message

Ondrej Bilka June 7, 2015, 8:52 p.m. UTC
Hi,

I decided to also improve memchr which I didn't do before as it was
relatively rarely called. I used same technique as strchr to get around 10% speedup and considerable decrease of its size.  

I use fact that memory area needs to be valid. That rules out values of
n in range -64...-1 where it could stop early instead browsing entire
memory. I could handle these with additional check if you want.

Also there is possible optimization to use that bsf sets zero flag to
save two tests, is that worth it?

	* sysdeps/x86_64/memchr.S (memchr): Improve implementation.

Comments

Ondrej Bilka June 16, 2015, 5:41 a.m. UTC | #1
ping
On Sun, Jun 07, 2015 at 10:52:44PM +0200, Ondřej Bílka wrote:
> Hi,
> 
> I decided to also improve memchr which I didn't do before as it was
> relatively rarely called. I used same technique as strchr to get around 10% speedup and considerable decrease of its size.  
> 
> I use fact that memory area needs to be valid. That rules out values of
> n in range -64...-1 where it could stop early instead browsing entire
> memory. I could handle these with additional check if you want.
> 
> Also there is possible optimization to use that bsf sets zero flag to
> save two tests, is that worth it?
> 
> 	* sysdeps/x86_64/memchr.S (memchr): Improve implementation.
> 
> diff --git a/sysdeps/x86_64/memchr.S b/sysdeps/x86_64/memchr.S
> index fae85ca..9649b1c 100644
> --- a/sysdeps/x86_64/memchr.S
> +++ b/sysdeps/x86_64/memchr.S
> @@ -1,5 +1,4 @@
> -/* Copyright (C) 2011-2015 Free Software Foundation, Inc.
> -   Contributed by Intel Corporation.
> +/* Copyright (C) 2015 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
> @@ -18,292 +17,134 @@
>  
>  #include <sysdep.h>
>  
> -/* fast SSE2 version with using pmaxub and 64 byte loop */
> +/* fast SSE2 version with using 64 byte loop */
>  
>  	.text
>  ENTRY(memchr)
> -	movd	%rsi, %xmm1
> -	mov	%rdi, %rcx
> -
> -	punpcklbw %xmm1, %xmm1
> -	test	%rdx, %rdx
> -	jz	L(return_null)
> -	punpcklbw %xmm1, %xmm1
> -
> -	and	$63, %rcx
> -	pshufd	$0, %xmm1, %xmm1
> -
> -	cmp	$48, %rcx
> -	ja	L(crosscache)
> -
> -	movdqu	(%rdi), %xmm0
> -	pcmpeqb	%xmm1, %xmm0
> -	pmovmskb %xmm0, %eax
> -	test	%eax, %eax
> -
> -	jnz	L(matches_1)
> -	sub	$16, %rdx
> -	jbe	L(return_null)
> -	add	$16, %rdi
> -	and	$15, %rcx
> -	and	$-16, %rdi
> -	add	%rcx, %rdx
> -	sub	$64, %rdx
> -	jbe	L(exit_loop)
> -	jmp	L(loop_prolog)
> -
> -	.p2align 4
> -L(crosscache):
> -	and	$15, %rcx
> -	and	$-16, %rdi
> -	movdqa	(%rdi), %xmm0
> -
> -	pcmpeqb	%xmm1, %xmm0
> -/* Check if there is a match.  */
> -	pmovmskb %xmm0, %eax
> -/* Remove the leading bytes.  */
> -	sar	%cl, %eax
> -	test	%eax, %eax
> -	je	L(unaligned_no_match)
> -/* Check which byte is a match.  */
> +	movd	%esi, %xmm2
> +	testq	%rdx, %rdx
> +	punpcklbw	%xmm2, %xmm2
> +	punpcklwd	%xmm2, %xmm2
> +	pshufd	$0, %xmm2, %xmm2
> +	je	L(return_null)
> +	movl	%edi, %eax
> +	andl	$4095, %eax
> +	cmpl	$4032, %eax
> +	jg	L(cross_page)
> +	movdqu	(%rdi), %xmm1
> +	pcmpeqb	%xmm2, %xmm1
> +	pmovmskb	%xmm1, %eax
> +	test	%eax, %eax
> +	je	L(next_48_bytes)
>  	bsf	%eax, %eax
> -
> -	sub	%rax, %rdx
> +	cmpq	%rax, %rdx
>  	jbe	L(return_null)
> -	add	%rdi, %rax
> -	add	%rcx, %rax
> -	ret
> -
> -	.p2align 4
> -L(unaligned_no_match):
> -	add	%rcx, %rdx
> -	sub	$16, %rdx
> +	addq	%rdi, %rax
> +		ret
> +.p2align	4,,10
> +.p2align	3
> +L(next_48_bytes):
> +	movdqu	16(%rdi), %xmm1
> +	movdqu	32(%rdi), %xmm3
> +	pcmpeqb	%xmm2, %xmm1
> +	pcmpeqb	%xmm2, %xmm3
> +	movdqu	48(%rdi), %xmm4
> +	pmovmskb	%xmm1, %esi
> +	pmovmskb	%xmm3, %ecx
> +	pcmpeqb	%xmm2, %xmm4
> +	pmovmskb	%xmm4, %eax
> +	salq	$32, %rcx
> +	sal	$16, %esi
> +	orq	%rsi, %rcx
> +	salq	$48, %rax
> +	orq	%rcx, %rax
> +	je	L(prepare_loop)
> +L(return):
> +	bsf	%rax, %rax
> +	cmpq	%rax, %rdx
>  	jbe	L(return_null)
> -	add	$16, %rdi
> -	sub	$64, %rdx
> -	jbe	L(exit_loop)
> -
> -	.p2align 4
> -L(loop_prolog):
> -	movdqa	(%rdi), %xmm0
> -	pcmpeqb	%xmm1, %xmm0
> -	pmovmskb %xmm0, %eax
> -	test	%eax, %eax
> -	jnz	L(matches)
> +	addq	%rdi, %rax
> +		ret
>  
> -	movdqa	16(%rdi), %xmm2
> -	pcmpeqb	%xmm1, %xmm2
> -	pmovmskb %xmm2, %eax
> -	test	%eax, %eax
> -	jnz	L(matches16)
> -
> -	movdqa	32(%rdi), %xmm3
> -	pcmpeqb	%xmm1, %xmm3
> -	pmovmskb %xmm3, %eax
> -	test	%eax, %eax
> -	jnz	L(matches32)
> -
> -	movdqa	48(%rdi), %xmm4
> -	pcmpeqb	%xmm1, %xmm4
> -	add	$64, %rdi
> -	pmovmskb %xmm4, %eax
> -	test	%eax, %eax
> -	jnz	L(matches0)
> -
> -	test	$0x3f, %rdi
> -	jz	L(align64_loop)
> -
> -	sub	$64, %rdx
> -	jbe	L(exit_loop)
> -
> -	movdqa	(%rdi), %xmm0
> -	pcmpeqb	%xmm1, %xmm0
> -	pmovmskb %xmm0, %eax
> -	test	%eax, %eax
> -	jnz	L(matches)
> -
> -	movdqa	16(%rdi), %xmm2
> -	pcmpeqb	%xmm1, %xmm2
> -	pmovmskb %xmm2, %eax
> -	test	%eax, %eax
> -	jnz	L(matches16)
> -
> -	movdqa	32(%rdi), %xmm3
> -	pcmpeqb	%xmm1, %xmm3
> -	pmovmskb %xmm3, %eax
> -	test	%eax, %eax
> -	jnz	L(matches32)
> -
> -	movdqa	48(%rdi), %xmm3
> -	pcmpeqb	%xmm1, %xmm3
> -	pmovmskb %xmm3, %eax
> -
> -	add	$64, %rdi
> -	test	%eax, %eax
> -	jnz	L(matches0)
> -
> -	mov	%rdi, %rcx
> -	and	$-64, %rdi
> -	and	$63, %rcx
> -	add	%rcx, %rdx
> -
> -	.p2align 4
> -L(align64_loop):
> -	sub	$64, %rdx
> -	jbe	L(exit_loop)
> -	movdqa	(%rdi), %xmm0
> -	movdqa	16(%rdi), %xmm2
> -	movdqa	32(%rdi), %xmm3
> -	movdqa	48(%rdi), %xmm4
> -
> -	pcmpeqb	%xmm1, %xmm0
> -	pcmpeqb	%xmm1, %xmm2
> -	pcmpeqb	%xmm1, %xmm3
> -	pcmpeqb	%xmm1, %xmm4
> -
> -	pmaxub	%xmm0, %xmm3
> -	pmaxub	%xmm2, %xmm4
> +.p2align	4,,10
> +.p2align	3
> +L(return_null):
> +	xorl	%eax, %eax
> +		ret
> +.p2align	4,,10
> +.p2align	4
> +L(prepare_loop):
> +	movq	%rdi, %rcx
> +	andq	$-64, %rcx
> +	subq	%rcx, %rdi
> +	leaq	(%rdx, %rdi), %rsi
> +.p2align	4,,10
> +.p2align	3
> +L(loop):
> +	subq	$64, %rsi
> +	jbe	L(return_null)
> +		
> +	movdqa	64(%rcx), %xmm0
> +	movdqa	80(%rcx), %xmm1
> +	movdqa	96(%rcx), %xmm3
> +	movdqa	112(%rcx), %xmm4
> +
> +	pcmpeqb	%xmm2, %xmm0
> +	pcmpeqb	%xmm2, %xmm1
> +	pcmpeqb	%xmm2, %xmm3
> +	pcmpeqb	%xmm2, %xmm4
> +
> +	pmaxub	%xmm0, %xmm1
> +	pmaxub	%xmm1, %xmm3
>  	pmaxub	%xmm3, %xmm4
> -	pmovmskb %xmm4, %eax
> -
> -	add	$64, %rdi
> -
> -	test	%eax, %eax
> -	jz	L(align64_loop)
> -
> -	sub	$64, %rdi
> -
> +	addq	$64, %rcx
> +	pmovmskb %xmm4, %edx
> +	testl	%edx, %edx
> +	je	L(loop)
> +	pmovmskb %xmm3, %r8d
> +	pmovmskb %xmm1, %edi
> +	salq	$48, %rdx
>  	pmovmskb %xmm0, %eax
> -	test	%eax, %eax
> -	jnz	L(matches)
> -
> -	pmovmskb %xmm2, %eax
> -	test	%eax, %eax
> -	jnz	L(matches16)
> -
> -	movdqa	32(%rdi), %xmm3
> -	pcmpeqb	%xmm1, %xmm3
> -
> -	pcmpeqb	48(%rdi), %xmm1
> -	pmovmskb %xmm3, %eax
> -	test	%eax, %eax
> -	jnz	L(matches32)
> -
> -	pmovmskb %xmm1, %eax
> -	bsf	%eax, %eax
> -	lea	48(%rdi, %rax), %rax
> -	ret
> -
> -	.p2align 4
> -L(exit_loop):
> -	add	$32, %rdx
> -	jle	L(exit_loop_32)
> -
> -	movdqa	(%rdi), %xmm0
> -	pcmpeqb	%xmm1, %xmm0
> -	pmovmskb %xmm0, %eax
> -	test	%eax, %eax
> -	jnz	L(matches)
> -
> -	movdqa	16(%rdi), %xmm2
> -	pcmpeqb	%xmm1, %xmm2
> -	pmovmskb %xmm2, %eax
> -	test	%eax, %eax
> -	jnz	L(matches16)
> -
> -	movdqa	32(%rdi), %xmm3
> -	pcmpeqb	%xmm1, %xmm3
> -	pmovmskb %xmm3, %eax
> -	test	%eax, %eax
> -	jnz	L(matches32_1)
> -	sub	$16, %rdx
> -	jle	L(return_null)
> -
> -	pcmpeqb	48(%rdi), %xmm1
> -	pmovmskb %xmm1, %eax
> -	test	%eax, %eax
> -	jnz	L(matches48_1)
> -	xor	%rax, %rax
> -	ret
> -
> -	.p2align 4
> -L(exit_loop_32):
> -	add	$32, %rdx
> -	movdqa	(%rdi), %xmm0
> -	pcmpeqb	%xmm1, %xmm0
> -	pmovmskb %xmm0, %eax
> -	test	%eax, %eax
> -	jnz	L(matches_1)
> -	sub	$16, %rdx
> -	jbe	L(return_null)
> -
> -	pcmpeqb	16(%rdi), %xmm1
> -	pmovmskb %xmm1, %eax
> -	test	%eax, %eax
> -	jnz	L(matches16_1)
> -	xor	%rax, %rax
> -	ret
> -
> -	.p2align 4
> -L(matches0):
> -	bsf	%eax, %eax
> -	lea	-16(%rax, %rdi), %rax
> -	ret
> -
> -	.p2align 4
> -L(matches):
> -	bsf	%eax, %eax
> -	add	%rdi, %rax
> -	ret
> -
> -	.p2align 4
> -L(matches16):
> -	bsf	%eax, %eax
> -	lea	16(%rax, %rdi), %rax
> -	ret
> -
> -	.p2align 4
> -L(matches32):
> -	bsf	%eax, %eax
> -	lea	32(%rax, %rdi), %rax
> -	ret
> -
> -	.p2align 4
> -L(matches_1):
> -	bsf	%eax, %eax
> -	sub	%rax, %rdx
> -	jbe	L(return_null)
> -	add	%rdi, %rax
> -	ret
> -
> -	.p2align 4
> -L(matches16_1):
> -	bsf	%eax, %eax
> -	sub	%rax, %rdx
> +	salq	$32, %r8
> +	sal	$16, %edi
> +	or	%edi, %eax
> +	orq	%r8, %rax
> +	orq	%rax, %rdx
> +	bsfq	%rdx, %rax
> +	cmp	%rax, %rsi
>  	jbe	L(return_null)
> -	lea	16(%rdi, %rax), %rax
> +	addq	%rcx, %rax
>  	ret
>  
> -	.p2align 4
> -L(matches32_1):
> -	bsf	%eax, %eax
> -	sub	%rax, %rdx
> -	jbe	L(return_null)
> -	lea	32(%rdi, %rax), %rax
> -	ret
> -
> -	.p2align 4
> -L(matches48_1):
> -	bsf	%eax, %eax
> -	sub	%rax, %rdx
> -	jbe	L(return_null)
> -	lea	48(%rdi, %rax), %rax
> -	ret
> -
> -	.p2align 4
> -L(return_null):
> -	xor	%rax, %rax
> -	ret
> +.p2align	4,,10
> +.p2align	3
> +L(cross_page):
> +	movq	%rdi, %rsi
> +	andq	$-64, %rsi
> +	movdqa	(%rsi), %xmm1
> +	pcmpeqb	%xmm2, %xmm1
> +	pmovmskb %xmm1, %ecx
> +	movdqa	16(%rsi), %xmm1
> +	pcmpeqb	%xmm2, %xmm1
> +	pmovmskb %xmm1, %eax
> +	movdqa	32(%rsi), %xmm1
> +	pcmpeqb	%xmm2, %xmm1
> +	sal	$16, %eax
> +	movdqa	%xmm2,	%xmm0
> +	pcmpeqb	48(%rsi), %xmm0
> +	pmovmskb %xmm1, %r8d
> +	pmovmskb %xmm0, %r9d
> +	salq	$32, %r8
> +	salq	$48, %r9
> +	or	%ecx, %eax
> +	orq	%r9, %rax
> +	orq	%r8, %rax
> +	movq	%rdi, %rcx
> +	subq	%rsi, %rcx
> +	shrq	%cl, %rax
> +	testq	%rax, %rax
> +	jne	L(return)
> +	jmp	L(prepare_loop)
>  END(memchr)
>  
>  strong_alias (memchr, __memchr)
Andrew Senkevich June 19, 2015, 11 a.m. UTC | #2
>ping

>On Sun, Jun 07, 2015 at 10:52:44PM +0200, Ondřej Bílka wrote:

>> Hi,

>> 

>> I decided to also improve memchr which I didn't do before as it was 

>> relatively rarely called. I used same technique as strchr to get around 10% speedup and considerable decrease of its size.

>> 

>> I use fact that memory area needs to be valid. That rules out values 

>> of n in range -64...-1 where it could stop early instead browsing 

>> entire memory. I could handle these with additional check if you want.

>> 

>> Also there is possible optimization to use that bsf sets zero flag to 

>> save two tests, is that worth it?

>> 

>> 	* sysdeps/x86_64/memchr.S (memchr): Improve implementation.

>> 

>> diff --git a/sysdeps/x86_64/memchr.S b/sysdeps/x86_64/memchr.S index 

>> fae85ca..9649b1c 100644

>> --- a/sysdeps/x86_64/memchr.S

>> +++ b/sysdeps/x86_64/memchr.S

>> @@ -1,5 +1,4 @@

>> -/* Copyright (C) 2011-2015 Free Software Foundation, Inc.

>> -   Contributed by Intel Corporation.

>> +/* Copyright (C) 2015 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 

>> @@ -18,292 +17,134 @@

>>  

>>  #include <sysdep.h>

>>  

>> -/* fast SSE2 version with using pmaxub and 64 byte loop */

>> +/* fast SSE2 version with using 64 byte loop */

>>  

>>  	.text

>>  ENTRY(memchr)

>> -	movd	%rsi, %xmm1

>> -	mov	%rdi, %rcx

>> -

>> -	punpcklbw %xmm1, %xmm1

>> -	test	%rdx, %rdx

>> -	jz	L(return_null)

>> -	punpcklbw %xmm1, %xmm1

>> -

>> -	and	$63, %rcx

>> -	pshufd	$0, %xmm1, %xmm1

>> -

>> -	cmp	$48, %rcx

>> -	ja	L(crosscache)

>> -

>> -	movdqu	(%rdi), %xmm0

>> -	pcmpeqb	%xmm1, %xmm0

>> -	pmovmskb %xmm0, %eax

>> -	test	%eax, %eax

>> -

>> -	jnz	L(matches_1)

>> -	sub	$16, %rdx

>> -	jbe	L(return_null)

>> -	add	$16, %rdi

>> -	and	$15, %rcx

>> -	and	$-16, %rdi

>> -	add	%rcx, %rdx

>> -	sub	$64, %rdx

>> -	jbe	L(exit_loop)

>> -	jmp	L(loop_prolog)

>> -

>> -	.p2align 4

>> -L(crosscache):

>> -	and	$15, %rcx

>> -	and	$-16, %rdi

>> -	movdqa	(%rdi), %xmm0

>> -

>> -	pcmpeqb	%xmm1, %xmm0

>> -/* Check if there is a match.  */

>> -	pmovmskb %xmm0, %eax

>> -/* Remove the leading bytes.  */

>> -	sar	%cl, %eax

>> -	test	%eax, %eax

>> -	je	L(unaligned_no_match)

>> -/* Check which byte is a match.  */

>> +	movd	%esi, %xmm2

>> +	testq	%rdx, %rdx

>> +	punpcklbw	%xmm2, %xmm2

>> +	punpcklwd	%xmm2, %xmm2

>> +	pshufd	$0, %xmm2, %xmm2

>> +	je	L(return_null)

>> +	movl	%edi, %eax

>> +	andl	$4095, %eax

>> +	cmpl	$4032, %eax

>> +	jg	L(cross_page)

>> +	movdqu	(%rdi), %xmm1

>> +	pcmpeqb	%xmm2, %xmm1

>> +	pmovmskb	%xmm1, %eax

>> +	test	%eax, %eax

>> +	je	L(next_48_bytes)

>>  	bsf	%eax, %eax

>> -

>> -	sub	%rax, %rdx

>> +	cmpq	%rax, %rdx

>>  	jbe	L(return_null)

>> -	add	%rdi, %rax

>> -	add	%rcx, %rax

>> -	ret

>> -

>> -	.p2align 4

>> -L(unaligned_no_match):

>> -	add	%rcx, %rdx

>> -	sub	$16, %rdx

>> +	addq	%rdi, %rax

>> +		ret

>> +.p2align	4,,10

>> +.p2align	3

>> +L(next_48_bytes):

>> +	movdqu	16(%rdi), %xmm1

>> +	movdqu	32(%rdi), %xmm3

>> +	pcmpeqb	%xmm2, %xmm1

>> +	pcmpeqb	%xmm2, %xmm3

>> +	movdqu	48(%rdi), %xmm4

>> +	pmovmskb	%xmm1, %esi

>> +	pmovmskb	%xmm3, %ecx

>> +	pcmpeqb	%xmm2, %xmm4

>> +	pmovmskb	%xmm4, %eax

>> +	salq	$32, %rcx

>> +	sal	$16, %esi

>> +	orq	%rsi, %rcx

>> +	salq	$48, %rax

>> +	orq	%rcx, %rax

>> +	je	L(prepare_loop)

>> +L(return):

>> +	bsf	%rax, %rax

>> +	cmpq	%rax, %rdx

>>  	jbe	L(return_null)

>> -	add	$16, %rdi

>> -	sub	$64, %rdx

>> -	jbe	L(exit_loop)

>> -

>> -	.p2align 4

>> -L(loop_prolog):

>> -	movdqa	(%rdi), %xmm0

>> -	pcmpeqb	%xmm1, %xmm0

>> -	pmovmskb %xmm0, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches)

>> +	addq	%rdi, %rax

>> +		ret

>>  

>> -	movdqa	16(%rdi), %xmm2

>> -	pcmpeqb	%xmm1, %xmm2

>> -	pmovmskb %xmm2, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches16)

>> -

>> -	movdqa	32(%rdi), %xmm3

>> -	pcmpeqb	%xmm1, %xmm3

>> -	pmovmskb %xmm3, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches32)

>> -

>> -	movdqa	48(%rdi), %xmm4

>> -	pcmpeqb	%xmm1, %xmm4

>> -	add	$64, %rdi

>> -	pmovmskb %xmm4, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches0)

>> -

>> -	test	$0x3f, %rdi

>> -	jz	L(align64_loop)

>> -

>> -	sub	$64, %rdx

>> -	jbe	L(exit_loop)

>> -

>> -	movdqa	(%rdi), %xmm0

>> -	pcmpeqb	%xmm1, %xmm0

>> -	pmovmskb %xmm0, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches)

>> -

>> -	movdqa	16(%rdi), %xmm2

>> -	pcmpeqb	%xmm1, %xmm2

>> -	pmovmskb %xmm2, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches16)

>> -

>> -	movdqa	32(%rdi), %xmm3

>> -	pcmpeqb	%xmm1, %xmm3

>> -	pmovmskb %xmm3, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches32)

>> -

>> -	movdqa	48(%rdi), %xmm3

>> -	pcmpeqb	%xmm1, %xmm3

>> -	pmovmskb %xmm3, %eax

>> -

>> -	add	$64, %rdi

>> -	test	%eax, %eax

>> -	jnz	L(matches0)

>> -

>> -	mov	%rdi, %rcx

>> -	and	$-64, %rdi

>> -	and	$63, %rcx

>> -	add	%rcx, %rdx

>> -

>> -	.p2align 4

>> -L(align64_loop):

>> -	sub	$64, %rdx

>> -	jbe	L(exit_loop)

>> -	movdqa	(%rdi), %xmm0

>> -	movdqa	16(%rdi), %xmm2

>> -	movdqa	32(%rdi), %xmm3

>> -	movdqa	48(%rdi), %xmm4

>> -

>> -	pcmpeqb	%xmm1, %xmm0

>> -	pcmpeqb	%xmm1, %xmm2

>> -	pcmpeqb	%xmm1, %xmm3

>> -	pcmpeqb	%xmm1, %xmm4

>> -

>> -	pmaxub	%xmm0, %xmm3

>> -	pmaxub	%xmm2, %xmm4

>> +.p2align	4,,10

>> +.p2align	3

>> +L(return_null):

>> +	xorl	%eax, %eax

>> +		ret

>> +.p2align	4,,10

>> +.p2align	4

>> +L(prepare_loop):

>> +	movq	%rdi, %rcx

>> +	andq	$-64, %rcx

>> +	subq	%rcx, %rdi

>> +	leaq	(%rdx, %rdi), %rsi

>> +.p2align	4,,10

>> +.p2align	3

>> +L(loop):

>> +	subq	$64, %rsi

>> +	jbe	L(return_null)

>> +		

>> +	movdqa	64(%rcx), %xmm0

>> +	movdqa	80(%rcx), %xmm1

>> +	movdqa	96(%rcx), %xmm3

>> +	movdqa	112(%rcx), %xmm4

>> +

>> +	pcmpeqb	%xmm2, %xmm0

>> +	pcmpeqb	%xmm2, %xmm1

>> +	pcmpeqb	%xmm2, %xmm3

>> +	pcmpeqb	%xmm2, %xmm4

>> +

>> +	pmaxub	%xmm0, %xmm1

>> +	pmaxub	%xmm1, %xmm3

>>  	pmaxub	%xmm3, %xmm4

>> -	pmovmskb %xmm4, %eax

>> -

>> -	add	$64, %rdi

>> -

>> -	test	%eax, %eax

>> -	jz	L(align64_loop)

>> -

>> -	sub	$64, %rdi

>> -

>> +	addq	$64, %rcx

>> +	pmovmskb %xmm4, %edx

>> +	testl	%edx, %edx

>> +	je	L(loop)

>> +	pmovmskb %xmm3, %r8d

>> +	pmovmskb %xmm1, %edi

>> +	salq	$48, %rdx

>>  	pmovmskb %xmm0, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches)

>> -

>> -	pmovmskb %xmm2, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches16)

>> -

>> -	movdqa	32(%rdi), %xmm3

>> -	pcmpeqb	%xmm1, %xmm3

>> -

>> -	pcmpeqb	48(%rdi), %xmm1

>> -	pmovmskb %xmm3, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches32)

>> -

>> -	pmovmskb %xmm1, %eax

>> -	bsf	%eax, %eax

>> -	lea	48(%rdi, %rax), %rax

>> -	ret

>> -

>> -	.p2align 4

>> -L(exit_loop):

>> -	add	$32, %rdx

>> -	jle	L(exit_loop_32)

>> -

>> -	movdqa	(%rdi), %xmm0

>> -	pcmpeqb	%xmm1, %xmm0

>> -	pmovmskb %xmm0, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches)

>> -

>> -	movdqa	16(%rdi), %xmm2

>> -	pcmpeqb	%xmm1, %xmm2

>> -	pmovmskb %xmm2, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches16)

>> -

>> -	movdqa	32(%rdi), %xmm3

>> -	pcmpeqb	%xmm1, %xmm3

>> -	pmovmskb %xmm3, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches32_1)

>> -	sub	$16, %rdx

>> -	jle	L(return_null)

>> -

>> -	pcmpeqb	48(%rdi), %xmm1

>> -	pmovmskb %xmm1, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches48_1)

>> -	xor	%rax, %rax

>> -	ret

>> -

>> -	.p2align 4

>> -L(exit_loop_32):

>> -	add	$32, %rdx

>> -	movdqa	(%rdi), %xmm0

>> -	pcmpeqb	%xmm1, %xmm0

>> -	pmovmskb %xmm0, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches_1)

>> -	sub	$16, %rdx

>> -	jbe	L(return_null)

>> -

>> -	pcmpeqb	16(%rdi), %xmm1

>> -	pmovmskb %xmm1, %eax

>> -	test	%eax, %eax

>> -	jnz	L(matches16_1)

>> -	xor	%rax, %rax

>> -	ret

>> -

>> -	.p2align 4

>> -L(matches0):

>> -	bsf	%eax, %eax

>> -	lea	-16(%rax, %rdi), %rax

>> -	ret

>> -

>> -	.p2align 4

>> -L(matches):

>> -	bsf	%eax, %eax

>> -	add	%rdi, %rax

>> -	ret

>> -

>> -	.p2align 4

>> -L(matches16):

>> -	bsf	%eax, %eax

>> -	lea	16(%rax, %rdi), %rax

>> -	ret

>> -

>> -	.p2align 4

>> -L(matches32):

>> -	bsf	%eax, %eax

>> -	lea	32(%rax, %rdi), %rax

>> -	ret

>> -

>> -	.p2align 4

>> -L(matches_1):

>> -	bsf	%eax, %eax

>> -	sub	%rax, %rdx

>> -	jbe	L(return_null)

>> -	add	%rdi, %rax

>> -	ret

>> -

>> -	.p2align 4

>> -L(matches16_1):

>> -	bsf	%eax, %eax

>> -	sub	%rax, %rdx

>> +	salq	$32, %r8

>> +	sal	$16, %edi

>> +	or	%edi, %eax

>> +	orq	%r8, %rax

>> +	orq	%rax, %rdx

>> +	bsfq	%rdx, %rax

>> +	cmp	%rax, %rsi

>>  	jbe	L(return_null)

>> -	lea	16(%rdi, %rax), %rax

>> +	addq	%rcx, %rax

>>  	ret

>>  

>> -	.p2align 4

>> -L(matches32_1):

>> -	bsf	%eax, %eax

>> -	sub	%rax, %rdx

>> -	jbe	L(return_null)

>> -	lea	32(%rdi, %rax), %rax

>> -	ret

>> -

>> -	.p2align 4

>> -L(matches48_1):

>> -	bsf	%eax, %eax

>> -	sub	%rax, %rdx

>> -	jbe	L(return_null)

>> -	lea	48(%rdi, %rax), %rax

>> -	ret

>> -

>> -	.p2align 4

>> -L(return_null):

>> -	xor	%rax, %rax

>> -	ret

>> +.p2align	4,,10

>> +.p2align	3

>> +L(cross_page):

>> +	movq	%rdi, %rsi

>> +	andq	$-64, %rsi

>> +	movdqa	(%rsi), %xmm1

>> +	pcmpeqb	%xmm2, %xmm1

>> +	pmovmskb %xmm1, %ecx

>> +	movdqa	16(%rsi), %xmm1

>> +	pcmpeqb	%xmm2, %xmm1

>> +	pmovmskb %xmm1, %eax

>> +	movdqa	32(%rsi), %xmm1

>> +	pcmpeqb	%xmm2, %xmm1

>> +	sal	$16, %eax

>> +	movdqa	%xmm2,	%xmm0

>> +	pcmpeqb	48(%rsi), %xmm0

>> +	pmovmskb %xmm1, %r8d

>> +	pmovmskb %xmm0, %r9d

>> +	salq	$32, %r8

>> +	salq	$48, %r9

>> +	or	%ecx, %eax

>> +	orq	%r9, %rax

>> +	orq	%r8, %rax

>> +	movq	%rdi, %rcx

>> +	subq	%rsi, %rcx

>> +	shrq	%cl, %rax

>> +	testq	%rax, %rax

>> +	jne	L(return)

>> +	jmp	L(prepare_loop)

>>  END(memchr)

>>  

>>  strong_alias (memchr, __memchr)


Looks good on Haswell and Skylake.


--
Andrew
diff mbox

Patch

diff --git a/sysdeps/x86_64/memchr.S b/sysdeps/x86_64/memchr.S
index fae85ca..9649b1c 100644
--- a/sysdeps/x86_64/memchr.S
+++ b/sysdeps/x86_64/memchr.S
@@ -1,5 +1,4 @@ 
-/* Copyright (C) 2011-2015 Free Software Foundation, Inc.
-   Contributed by Intel Corporation.
+/* Copyright (C) 2015 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
@@ -18,292 +17,134 @@ 
 
 #include <sysdep.h>
 
-/* fast SSE2 version with using pmaxub and 64 byte loop */
+/* fast SSE2 version with using 64 byte loop */
 
 	.text
 ENTRY(memchr)
-	movd	%rsi, %xmm1
-	mov	%rdi, %rcx
-
-	punpcklbw %xmm1, %xmm1
-	test	%rdx, %rdx
-	jz	L(return_null)
-	punpcklbw %xmm1, %xmm1
-
-	and	$63, %rcx
-	pshufd	$0, %xmm1, %xmm1
-
-	cmp	$48, %rcx
-	ja	L(crosscache)
-
-	movdqu	(%rdi), %xmm0
-	pcmpeqb	%xmm1, %xmm0
-	pmovmskb %xmm0, %eax
-	test	%eax, %eax
-
-	jnz	L(matches_1)
-	sub	$16, %rdx
-	jbe	L(return_null)
-	add	$16, %rdi
-	and	$15, %rcx
-	and	$-16, %rdi
-	add	%rcx, %rdx
-	sub	$64, %rdx
-	jbe	L(exit_loop)
-	jmp	L(loop_prolog)
-
-	.p2align 4
-L(crosscache):
-	and	$15, %rcx
-	and	$-16, %rdi
-	movdqa	(%rdi), %xmm0
-
-	pcmpeqb	%xmm1, %xmm0
-/* Check if there is a match.  */
-	pmovmskb %xmm0, %eax
-/* Remove the leading bytes.  */
-	sar	%cl, %eax
-	test	%eax, %eax
-	je	L(unaligned_no_match)
-/* Check which byte is a match.  */
+	movd	%esi, %xmm2
+	testq	%rdx, %rdx
+	punpcklbw	%xmm2, %xmm2
+	punpcklwd	%xmm2, %xmm2
+	pshufd	$0, %xmm2, %xmm2
+	je	L(return_null)
+	movl	%edi, %eax
+	andl	$4095, %eax
+	cmpl	$4032, %eax
+	jg	L(cross_page)
+	movdqu	(%rdi), %xmm1
+	pcmpeqb	%xmm2, %xmm1
+	pmovmskb	%xmm1, %eax
+	test	%eax, %eax
+	je	L(next_48_bytes)
 	bsf	%eax, %eax
-
-	sub	%rax, %rdx
+	cmpq	%rax, %rdx
 	jbe	L(return_null)
-	add	%rdi, %rax
-	add	%rcx, %rax
-	ret
-
-	.p2align 4
-L(unaligned_no_match):
-	add	%rcx, %rdx
-	sub	$16, %rdx
+	addq	%rdi, %rax
+		ret
+.p2align	4,,10
+.p2align	3
+L(next_48_bytes):
+	movdqu	16(%rdi), %xmm1
+	movdqu	32(%rdi), %xmm3
+	pcmpeqb	%xmm2, %xmm1
+	pcmpeqb	%xmm2, %xmm3
+	movdqu	48(%rdi), %xmm4
+	pmovmskb	%xmm1, %esi
+	pmovmskb	%xmm3, %ecx
+	pcmpeqb	%xmm2, %xmm4
+	pmovmskb	%xmm4, %eax
+	salq	$32, %rcx
+	sal	$16, %esi
+	orq	%rsi, %rcx
+	salq	$48, %rax
+	orq	%rcx, %rax
+	je	L(prepare_loop)
+L(return):
+	bsf	%rax, %rax
+	cmpq	%rax, %rdx
 	jbe	L(return_null)
-	add	$16, %rdi
-	sub	$64, %rdx
-	jbe	L(exit_loop)
-
-	.p2align 4
-L(loop_prolog):
-	movdqa	(%rdi), %xmm0
-	pcmpeqb	%xmm1, %xmm0
-	pmovmskb %xmm0, %eax
-	test	%eax, %eax
-	jnz	L(matches)
+	addq	%rdi, %rax
+		ret
 
-	movdqa	16(%rdi), %xmm2
-	pcmpeqb	%xmm1, %xmm2
-	pmovmskb %xmm2, %eax
-	test	%eax, %eax
-	jnz	L(matches16)
-
-	movdqa	32(%rdi), %xmm3
-	pcmpeqb	%xmm1, %xmm3
-	pmovmskb %xmm3, %eax
-	test	%eax, %eax
-	jnz	L(matches32)
-
-	movdqa	48(%rdi), %xmm4
-	pcmpeqb	%xmm1, %xmm4
-	add	$64, %rdi
-	pmovmskb %xmm4, %eax
-	test	%eax, %eax
-	jnz	L(matches0)
-
-	test	$0x3f, %rdi
-	jz	L(align64_loop)
-
-	sub	$64, %rdx
-	jbe	L(exit_loop)
-
-	movdqa	(%rdi), %xmm0
-	pcmpeqb	%xmm1, %xmm0
-	pmovmskb %xmm0, %eax
-	test	%eax, %eax
-	jnz	L(matches)
-
-	movdqa	16(%rdi), %xmm2
-	pcmpeqb	%xmm1, %xmm2
-	pmovmskb %xmm2, %eax
-	test	%eax, %eax
-	jnz	L(matches16)
-
-	movdqa	32(%rdi), %xmm3
-	pcmpeqb	%xmm1, %xmm3
-	pmovmskb %xmm3, %eax
-	test	%eax, %eax
-	jnz	L(matches32)
-
-	movdqa	48(%rdi), %xmm3
-	pcmpeqb	%xmm1, %xmm3
-	pmovmskb %xmm3, %eax
-
-	add	$64, %rdi
-	test	%eax, %eax
-	jnz	L(matches0)
-
-	mov	%rdi, %rcx
-	and	$-64, %rdi
-	and	$63, %rcx
-	add	%rcx, %rdx
-
-	.p2align 4
-L(align64_loop):
-	sub	$64, %rdx
-	jbe	L(exit_loop)
-	movdqa	(%rdi), %xmm0
-	movdqa	16(%rdi), %xmm2
-	movdqa	32(%rdi), %xmm3
-	movdqa	48(%rdi), %xmm4
-
-	pcmpeqb	%xmm1, %xmm0
-	pcmpeqb	%xmm1, %xmm2
-	pcmpeqb	%xmm1, %xmm3
-	pcmpeqb	%xmm1, %xmm4
-
-	pmaxub	%xmm0, %xmm3
-	pmaxub	%xmm2, %xmm4
+.p2align	4,,10
+.p2align	3
+L(return_null):
+	xorl	%eax, %eax
+		ret
+.p2align	4,,10
+.p2align	4
+L(prepare_loop):
+	movq	%rdi, %rcx
+	andq	$-64, %rcx
+	subq	%rcx, %rdi
+	leaq	(%rdx, %rdi), %rsi
+.p2align	4,,10
+.p2align	3
+L(loop):
+	subq	$64, %rsi
+	jbe	L(return_null)
+		
+	movdqa	64(%rcx), %xmm0
+	movdqa	80(%rcx), %xmm1
+	movdqa	96(%rcx), %xmm3
+	movdqa	112(%rcx), %xmm4
+
+	pcmpeqb	%xmm2, %xmm0
+	pcmpeqb	%xmm2, %xmm1
+	pcmpeqb	%xmm2, %xmm3
+	pcmpeqb	%xmm2, %xmm4
+
+	pmaxub	%xmm0, %xmm1
+	pmaxub	%xmm1, %xmm3
 	pmaxub	%xmm3, %xmm4
-	pmovmskb %xmm4, %eax
-
-	add	$64, %rdi
-
-	test	%eax, %eax
-	jz	L(align64_loop)
-
-	sub	$64, %rdi
-
+	addq	$64, %rcx
+	pmovmskb %xmm4, %edx
+	testl	%edx, %edx
+	je	L(loop)
+	pmovmskb %xmm3, %r8d
+	pmovmskb %xmm1, %edi
+	salq	$48, %rdx
 	pmovmskb %xmm0, %eax
-	test	%eax, %eax
-	jnz	L(matches)
-
-	pmovmskb %xmm2, %eax
-	test	%eax, %eax
-	jnz	L(matches16)
-
-	movdqa	32(%rdi), %xmm3
-	pcmpeqb	%xmm1, %xmm3
-
-	pcmpeqb	48(%rdi), %xmm1
-	pmovmskb %xmm3, %eax
-	test	%eax, %eax
-	jnz	L(matches32)
-
-	pmovmskb %xmm1, %eax
-	bsf	%eax, %eax
-	lea	48(%rdi, %rax), %rax
-	ret
-
-	.p2align 4
-L(exit_loop):
-	add	$32, %rdx
-	jle	L(exit_loop_32)
-
-	movdqa	(%rdi), %xmm0
-	pcmpeqb	%xmm1, %xmm0
-	pmovmskb %xmm0, %eax
-	test	%eax, %eax
-	jnz	L(matches)
-
-	movdqa	16(%rdi), %xmm2
-	pcmpeqb	%xmm1, %xmm2
-	pmovmskb %xmm2, %eax
-	test	%eax, %eax
-	jnz	L(matches16)
-
-	movdqa	32(%rdi), %xmm3
-	pcmpeqb	%xmm1, %xmm3
-	pmovmskb %xmm3, %eax
-	test	%eax, %eax
-	jnz	L(matches32_1)
-	sub	$16, %rdx
-	jle	L(return_null)
-
-	pcmpeqb	48(%rdi), %xmm1
-	pmovmskb %xmm1, %eax
-	test	%eax, %eax
-	jnz	L(matches48_1)
-	xor	%rax, %rax
-	ret
-
-	.p2align 4
-L(exit_loop_32):
-	add	$32, %rdx
-	movdqa	(%rdi), %xmm0
-	pcmpeqb	%xmm1, %xmm0
-	pmovmskb %xmm0, %eax
-	test	%eax, %eax
-	jnz	L(matches_1)
-	sub	$16, %rdx
-	jbe	L(return_null)
-
-	pcmpeqb	16(%rdi), %xmm1
-	pmovmskb %xmm1, %eax
-	test	%eax, %eax
-	jnz	L(matches16_1)
-	xor	%rax, %rax
-	ret
-
-	.p2align 4
-L(matches0):
-	bsf	%eax, %eax
-	lea	-16(%rax, %rdi), %rax
-	ret
-
-	.p2align 4
-L(matches):
-	bsf	%eax, %eax
-	add	%rdi, %rax
-	ret
-
-	.p2align 4
-L(matches16):
-	bsf	%eax, %eax
-	lea	16(%rax, %rdi), %rax
-	ret
-
-	.p2align 4
-L(matches32):
-	bsf	%eax, %eax
-	lea	32(%rax, %rdi), %rax
-	ret
-
-	.p2align 4
-L(matches_1):
-	bsf	%eax, %eax
-	sub	%rax, %rdx
-	jbe	L(return_null)
-	add	%rdi, %rax
-	ret
-
-	.p2align 4
-L(matches16_1):
-	bsf	%eax, %eax
-	sub	%rax, %rdx
+	salq	$32, %r8
+	sal	$16, %edi
+	or	%edi, %eax
+	orq	%r8, %rax
+	orq	%rax, %rdx
+	bsfq	%rdx, %rax
+	cmp	%rax, %rsi
 	jbe	L(return_null)
-	lea	16(%rdi, %rax), %rax
+	addq	%rcx, %rax
 	ret
 
-	.p2align 4
-L(matches32_1):
-	bsf	%eax, %eax
-	sub	%rax, %rdx
-	jbe	L(return_null)
-	lea	32(%rdi, %rax), %rax
-	ret
-
-	.p2align 4
-L(matches48_1):
-	bsf	%eax, %eax
-	sub	%rax, %rdx
-	jbe	L(return_null)
-	lea	48(%rdi, %rax), %rax
-	ret
-
-	.p2align 4
-L(return_null):
-	xor	%rax, %rax
-	ret
+.p2align	4,,10
+.p2align	3
+L(cross_page):
+	movq	%rdi, %rsi
+	andq	$-64, %rsi
+	movdqa	(%rsi), %xmm1
+	pcmpeqb	%xmm2, %xmm1
+	pmovmskb %xmm1, %ecx
+	movdqa	16(%rsi), %xmm1
+	pcmpeqb	%xmm2, %xmm1
+	pmovmskb %xmm1, %eax
+	movdqa	32(%rsi), %xmm1
+	pcmpeqb	%xmm2, %xmm1
+	sal	$16, %eax
+	movdqa	%xmm2,	%xmm0
+	pcmpeqb	48(%rsi), %xmm0
+	pmovmskb %xmm1, %r8d
+	pmovmskb %xmm0, %r9d
+	salq	$32, %r8
+	salq	$48, %r9
+	or	%ecx, %eax
+	orq	%r9, %rax
+	orq	%r8, %rax
+	movq	%rdi, %rcx
+	subq	%rsi, %rcx
+	shrq	%cl, %rax
+	testq	%rax, %rax
+	jne	L(return)
+	jmp	L(prepare_loop)
 END(memchr)
 
 strong_alias (memchr, __memchr)