From: "Joseph S. Myers" <jsm28@cam.ac.uk>
To: Zack Weinberg <zack@codesourcery.com>
Cc: Andrew Pinski <pinskia@physics.uc.edu>, <gcc@gcc.gnu.org>,
<apinski@apple.com>
Subject: Re: speeding up parts of gcc by using ffs
Date: Mon, 06 Jan 2003 18:28:00 -0000 [thread overview]
Message-ID: <Pine.LNX.4.33.0301061824580.11139-100000@kern.srcf.societies.cam.ac.uk> (raw)
In-Reply-To: <87ptraf9sp.fsf@egil.codesourcery.com>
On Mon, 6 Jan 2003, Zack Weinberg wrote:
> glibc provides ffsl and ffsll which take 'long' and 'long long'
> respectively; may I suggest that you follow these steps:
>
> 1) put ffsl and ffsll into libiberty.
> 2) have hwint.h #define ffs_hwi and ffs_hwidesti appropriately
> 3) use ffs/ffsl/ffsll/ffs_hwi throughout the compiler
> 4) create __builtin_ffsl and __builtin_ffsll
If any of the uses are genuinely performance-critical (as shown by
profiling), the fallback version of ffs (and ffsl, ffsll) in libiberty
could also be speeded up by replacing it with glibc's generic C
implementation.
--
Joseph S. Myers
jsm28@cam.ac.uk
next prev parent reply other threads:[~2003-01-06 18:27 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-01-05 6:16 speeding up parts of gcc by using count_leading_zero (long) Andrew Pinski
2003-01-05 7:03 ` Zack Weinberg
2003-01-05 7:17 ` Peter Barada
2003-01-05 8:41 ` Zack Weinberg
2003-01-06 10:51 ` speeding up parts of gcc by using ffs Andrew Pinski
2003-01-06 18:08 ` Zack Weinberg
2003-01-06 18:28 ` Joseph S. Myers [this message]
2003-01-08 9:51 ` Andrew Pinski
2003-01-08 11:20 ` Falk Hueffner
2003-01-08 11:21 ` Andrew Pinski
2003-01-08 11:26 ` Falk Hueffner
2003-01-09 0:24 ` Richard Henderson
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