This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: Correct prefetch hint in power7 memrchr
- From: Adhemerval Zanella <azanella at linux dot vnet dot ibm dot com>
- To: libc-alpha at sourceware dot org
- Date: Tue, 25 Mar 2014 16:07:38 -0300
- Subject: Re: Correct prefetch hint in power7 memrchr
- Authentication-results: sourceware.org; auth=none
- References: <20140325020430 dot GE18201 at bubble dot grove dot modra dot org>
On 24-03-2014 23:04, Alan Modra wrote:
> Typo fix. Discovered when looking at some disassembly, and wondering
> why this disassembled as dcbtt. My simple benchmark testing didn't
> show any effect of using the wrong hint, but at a guess you'd only see
> a difference on a very long memrchr with cold caches.
>
> * sysdeps/powerpc/powerpc64/power7/memrchr.S: Correct stream hint.
>
> diff --git a/sysdeps/powerpc/powerpc64/power7/memrchr.S b/sysdeps/powerpc/powerpc64/power7/memrchr.S
> index 40e436f..0c01ca2 100644
> --- a/sysdeps/powerpc/powerpc64/power7/memrchr.S
> +++ b/sysdeps/powerpc/powerpc64/power7/memrchr.S
> @@ -29,7 +29,7 @@ ENTRY (__memrchr)
> mr r10,r3
> clrrdi r6,r7,7
> li r9,3<<5
> - dcbt r9,r6,16 /* Stream hint, decreasing addresses. */
> + dcbt r9,r6,8 /* Stream hint, decreasing addresses. */
>
> /* Replicate BYTE to doubleword. */
> insrdi r4,r4,8,48
>
This patch is ok, thanks Alan.