[Bug c/17614] New: Integer Division produces a Floating exception.

[Bug c/17614] New: Integer Division produces a Floating exception.

[ppelissi at caramail dot com]

The following program:

int main()
{
  long double d, e;
  d = 1.0; while ((e = d / 2.0) != (long double) 0.0) d = e;
  return 0;
}

loops forever if it is compiled without optimization:

spe149.testdrive.hp.com> /tmp/make/bin/gcc test4.c -mfp-rounding-mode=d
-mieee-with-inexact
spe149.testdrive.hp.com> time ./a.out
^C0.405u 4.378s 0:04.79 99.5%   10+174k 0+0io 0pf+0w
spe149.testdrive.hp.com> /tmp/make/bin/gcc test4.c -mfp-rounding-mode=d
-mieee-with-inexact -O2
spe149.testdrive.hp.com> time ./a.out
0.000u 0.004s 0:00.00 0.0%      0+0k 0+0io 0pf+0w
spe149.testdrive.hp.com> /tmp/make/bin/gcc -v
Reading specs from /tmp/make/lib/gcc/alpha-unknown-freebsd5.2.1/3.4.2/specs
Configured with: ./configure --prefix=/tmp/gcc : (reconfigured) ./configure
--prefix=/tmp/gcc : (reconfigured) ./configure --prefix=/tmp/make
--enable-languages=c
Thread model: posix
gcc version 3.4.2

The same problem appears with GCC 3.3.3 [FreeBSD] 20031106

-- 
           Summary: Integer Division produces a Floating exception.
           Product: gcc
           Version: 3.4.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ppelissi at caramail dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: alpha-unknown-freebsd5.2.1
  GCC host triplet: alpha-unknown-freebsd5.2.1
GCC target triplet: alpha-unknown-freebsd5.2.1


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17614

[Bug c/17614] long double / -mfp-rounding-mode=d

[ppelissi at caramail dot com]

-mieee-with-inexact
X-Bugzilla-Reason: CC



-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Integer Division produces a |long double / -mfp-rounding-
                   |Floating exception.         |mode=d


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17614

[Bug target/17614] long double / -mfp-rounding-mode=d-mieee-with-inexact

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c                           |target
            Summary|long double / -mfp-rounding-|long double / -mfp-rounding-
                   |mode=d                      |mode=d-mieee-with-inexact


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17614

[Bug target/17614] long double / -mfp-rounding-mode=d -mieee-with-inexact

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-09-22 18:06 -------
Well it should as you used -mfp-rounding-mode=d

Dynamic rounding mode. A field in the floating point control register (fpcr, see Alpha architecture 
reference manual) controls the rounding mode in effect. The C library initializes this register for 
rounding towards plus infinity. Thus, unless your program modifies the fpcr, d corresponds to round 
towards plus infinity.

Since you are rounding towards postive infinity you will never reach zero.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID
            Summary|long double / -mfp-rounding-|long double / -mfp-rounding-
                   |mode=d-mieee-with-inexact   |mode=d -mieee-with-inexact


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17614