c/7437: Identical unsigned int calculations differ by 1, depending on number of steps in calculation.

[Geoff Keating]

The following reply was made to PR c/7437; it has been noted by GNATS.

From: Geoff Keating <geoffk@geoffk.org>
To: sewell@dramail.com
Cc: gcc-gnats@gcc.gnu.org
Subject: Re: c/7437: Identical unsigned int calculations differ by 1, depending on number of steps in calculation.
Date: 29 Jul 2002 15:33:55 -0700

 This is covered in the manual:
 
    * On 68000 and x86 systems, for instance, you can get paradoxical
      results if you test the precise values of floating point numbers.
      For example, you can find that a floating point value which is not
      a NaN is not equal to itself.  This results from the fact that the
      floating point registers hold a few more bits of precision than
      fit in a `double' in memory.  Compiled code moves values between
      memory and floating point registers at its convenience, and moving
      them into memory truncates them.
 
      You can partially avoid this problem by using the `-ffloat-store'
      option (*note Optimize Options::).
 
 -- 
 - Geoffrey Keating <geoffk@geoffk.org> <geoffk@redhat.com>