[PATCH, ARM] Fix minor issues in memchr NEON implementation

[PATCH, ARM] Fix minor issues in memchr NEON implementation

[Prakhar Bahuguna]

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The NEON-optimised implementation of memchr has a couple of minor issues - it
does not mask off the higher bits of the input character, and it uses a signed
comparison instead of unsigned within the smallstr loop. This patch addresses
both of these issues.

ChangeLog:

2017-06-02  Prakhar Bahuguna  <prakhar.bahuguna@arm.com>

	* libc/machine/arm/memchr.S: Add and instruction to mask off all but
	the lowest byte.
	Change blt to blo.

Okay for master?

-- 

Prakhar Bahuguna

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From ac13527b4d7a5f91088920c59bc53b0a771858e1 Mon Sep 17 00:00:00 2001
From: Prakhar Bahuguna <prakhar.bahuguna@arm.com>
Date: Fri, 2 Jun 2017 10:22:32 +0100
Subject: [PATCH] Fix minor issues in memchr NEON implementation

---
 newlib/libc/machine/arm/memchr.S | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/newlib/libc/machine/arm/memchr.S b/newlib/libc/machine/arm/memchr.S
index b5dcf83c0..7c22b117e 100644
--- a/newlib/libc/machine/arm/memchr.S
+++ b/newlib/libc/machine/arm/memchr.S
@@ -135,10 +135,11 @@ memchr:
 	/* Use a simple loop if there are less than 8 bytes to search.  */
 	cmp	cntin, #7
 	bhi	.Llargestr
+	and	chrin, chrin, #0xff
 
 .Lsmallstr:
 	subs	cntin, cntin, #1
-	blt	.Lnotfound	/* Return not found if reached end.  */
+	blo	.Lnotfound	/* Return not found if reached end.  */
 	ldrb	tmp, [srcin], #1
 	cmp	tmp, chrin
 	bne	.Lsmallstr	/* Loop again if not found.  */
-- 
2.13.0

Re: [PATCH, ARM] Fix minor issues in memchr NEON implementation

[Corinna Vinschen]

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On Jun  2 11:22, Prakhar Bahuguna wrote:
> The NEON-optimised implementation of memchr has a couple of minor issues - it
> does not mask off the higher bits of the input character, and it uses a signed
> comparison instead of unsigned within the smallstr loop. This patch addresses
> both of these issues.
> 
> ChangeLog:
> 
> 2017-06-02  Prakhar Bahuguna  <prakhar.bahuguna@arm.com>
> 
> 	* libc/machine/arm/memchr.S: Add and instruction to mask off all but
> 	the lowest byte.
> 	Change blt to blo.
> 
> Okay for master?

Yes, pushed.


Thanks,
Corinna

-- 
Corinna Vinschen
Cygwin Maintainer
Red Hat

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