This is the mail archive of the gcc@gcc.gnu.org mailing list for the GCC project.

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]
Other format:	[Raw text]

Re: Performance analysis of Polyhedron/gas_dyn

From: "Andrew Pinski" <pinskia at gmail dot com>
To: "Richard Guenther" <richard dot guenther at gmail dot com>
Cc: "Janne Blomqvist" <blomqvist dot janne at gmail dot com>, gfortran <fortran at gcc dot gnu dot org>, gcc at gcc dot gnu dot org
Date: Fri, 27 Apr 2007 02:14:06 -0700
Subject: Re: Performance analysis of Polyhedron/gas_dyn
References: <4631A891.5020002@gmail.com> <84fc9c000704270127s4eb0030p9d27fd5fdff73cf8@mail.gmail.com>

On 4/27/07, Richard Guenther <richard.guenther@gmail.com> wrote:

I think that even with -ffast-math 12 bits accuracy is not ok.  There is
the possibility of doing another newton iteration step to improve
accuracy, that would be ok for -ffast-math.  We can, though, add an
extra flag -msserecip or however you'd call it to enable use of the
instructions with less accuracy.


Which is already done for PPC at least the scalar code, see -mswdiv
option.  We don't do this for sqrt reciprocal yet but it is easy to
special case for the reciprocal case :).

-- Pinski

References:
- Re: Performance analysis of Polyhedron/gas_dyn
  - From: Richard Guenther

Index Nav:	[Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav:	[Date Prev] [Date Next]	[Thread Prev] [Thread Next]