Date: Fri, 19 Jun 2009 04:10:04 GMT From: Jay Howard <jhoward@alumni.utexas.net> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/135718: [PATCH] enhance qsort(3) to properly handle 32-bit aligned data on 64-bit systems Message-ID: <200906190410.n5J4A4D6028495@freefall.freebsd.org>
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The following reply was made to PR kern/135718; it has been noted by GNATS.
From: Jay Howard <jhoward@alumni.utexas.net>
To: bug-followup@FreeBSD.org
Cc:
Subject: Re: kern/135718: [PATCH] enhance qsort(3) to properly handle 32-bit
aligned data on 64-bit systems
Date: Thu, 18 Jun 2009 22:33:15 -0500
--0016e6db61c045af8e046cab2fd7
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It occurs to me that a simpler solution would to just do int-by-int swaps in
all cases when the base addr and element size are int-aligned, char-by-char
swaps when they're not, and an inline long-swap when the base addr is
long-aligned and element size is exactly sizeof(long).
It's notable that BSD bcopy() only does int-by-int copying and makes no
effort to do long-by-long copying when the data would permit
Here's a second patch that makes the above change.
On systems where sizeof(int) = sizeof(long) this version becomes identical
to the current version. When sizeof(long) > sizeof(int) bulk swapping
happens int-by-int instead of long-by-long. Inline swaps are still used
when the base is long-aligned and element size = sizeof(long).
uuencoded:
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--0016e6db61c045af8e046cab2fd7
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It occurs to me that a simpler solution would to just do int-by-int swaps i=
n all cases when the base addr and element size are int-aligned, char-by-ch=
ar swaps when they're not, and an inline long-swap when the base addr i=
s long-aligned and element size is exactly sizeof(long).<br>
<br>It's notable that BSD bcopy() only does int-by-int copying and make=
s no effort to do long-by-long copying when the data would permit<br><br>He=
re's a second patch that makes the above change.<br><br>On systems wher=
e sizeof(int) =3D sizeof(long) this version becomes identical to the curren=
t version.=A0 When sizeof(long) > sizeof(int) bulk swapping happens int-=
by-int instead of long-by-long.=A0 Inline swaps are still used when the bas=
e is long-aligned and element size =3D sizeof(long).<br>
<br>uuencoded:<br><br>begin 600 qsort.c.patch<br>M+2TM('%S;W)T+F,),C`P.=
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"B!]"BP@<br>`<br>end<br><br>
--0016e6db61c045af8e046cab2fd7--
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