[Bug other/14708] New: description of -ffloat-store in gcc man page incorrect/inaccurate

[debian-gcc at lists dot debian dot org]

[forwarded from http://bugs.debian.org/233673]

The gcc man page says:

    -ffloat-store
        Do  not  store floating point variables in registers.  This pre-
        vents undesirable excess precision on machines such as the 68000
        where  the floating registers (of the 68881) keep more precision
        than a double is supposed to have.

        For most programs, the excess precision does only  good,  but  a
        few  programs  rely  on  the precise definition of IEEE floating
        point.  Use `-ffloat-store' for such programs.

The second paragraph is incorrect. The IEEE754 standard has nothing
to do with that since it allows extended precision for intermediate
computations. This option just makes gcc more ISO C compliant, since
the ISO C forbids excess precision after an explicit conversion to
double (cast or affectation).

-- 
           Summary: description of -ffloat-store in gcc man page
                    incorrect/inaccurate
           Product: gcc
           Version: 3.3.4
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: other
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: debian-gcc at lists dot debian dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14708