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From: Richard Henderson <rth@cygnus.com>
To: Bill Broadley <bill@math.ucdavis.edu>
Cc: rth@cygnus.com, egcs@cygnus.com
Subject: Re: EGCS-1.0.2 pre fails on Spec CPU 95
Date: Mon, 16 Mar 1998 20:25:00 -0000	[thread overview]
Message-ID: <19980316162736.53280@dot.cygnus.com> (raw)
In-Reply-To: <199803091938.LAA29969@proto.math.ucdavis.edu>

On Mon, Mar 09, 1998 at 11:38:51AM -0800, Bill Broadley wrote:
> Running '146.wave5'
> Error comparing benchmark '146.wave5'

Turns out this is a problem between the spec test and the i386 fpu. 
Having the calculations done at the wrong precision results in 
slightly different end results.

There are two solutions: -ffloat-store, which will completely kill
any sort of performance, or changing the rounding mode in the fpu.

I would go for the later.  On Linux at least, the attached program
may be compiled with

  gcc -O -o libieee-dbl.a libieee-dbl.c

install the result in some convenient directory and add

  146.wave5=default=default:
  EXTRA_LIBS= -lieee-dbl

to your Spec95 config file.  Other Intel operating systems will only
require minor modifications, possibly using inline asm rather than a
library function.


r~

       reply	other threads:[~1998-03-16 20:25 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <19980309091650.64067@dot.cygnus.com>
     [not found] ` <199803091938.LAA29969@proto.math.ucdavis.edu>
1998-03-16 20:25   ` Richard Henderson [this message]
1998-03-04 14:54 Bill Broadley
1998-03-08 12:12 ` Dave Love
1998-03-08 22:51   ` Jeffrey A Law
1998-03-09  4:44     ` Dave Love
1998-03-09 10:31       ` Jeffrey A Law
1998-03-10 11:36         ` Dave Love

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