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* [Bug c/17614] New: Integer Division produces a Floating exception.
@ 2004-09-22 15:59 ppelissi at caramail dot com
2004-09-22 16:00 ` [Bug c/17614] long double / -mfp-rounding-mode=d ppelissi at caramail dot com
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: ppelissi at caramail dot com @ 2004-09-22 15:59 UTC (permalink / raw)
To: gcc-bugs
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
^ permalink raw reply [flat|nested] 4+ messages in thread* [Bug c/17614] long double / -mfp-rounding-mode=d 2004-09-22 15:59 [Bug c/17614] New: Integer Division produces a Floating exception ppelissi at caramail dot com @ 2004-09-22 16:00 ` ppelissi at caramail dot com 2004-09-22 17:32 ` [Bug target/17614] long double / -mfp-rounding-mode=d-mieee-with-inexact pinskia at gcc dot gnu dot org 2004-09-22 18:06 ` [Bug target/17614] long double / -mfp-rounding-mode=d -mieee-with-inexact pinskia at gcc dot gnu dot org 2 siblings, 0 replies; 4+ messages in thread From: ppelissi at caramail dot com @ 2004-09-22 16:00 UTC (permalink / raw) To: gcc-bugs -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 ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug target/17614] long double / -mfp-rounding-mode=d-mieee-with-inexact 2004-09-22 15:59 [Bug c/17614] New: Integer Division produces a Floating exception ppelissi at caramail dot com 2004-09-22 16:00 ` [Bug c/17614] long double / -mfp-rounding-mode=d ppelissi at caramail dot com @ 2004-09-22 17:32 ` pinskia at gcc dot gnu dot org 2004-09-22 18:06 ` [Bug target/17614] long double / -mfp-rounding-mode=d -mieee-with-inexact pinskia at gcc dot gnu dot org 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu dot org @ 2004-09-22 17:32 UTC (permalink / raw) To: gcc-bugs -- 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 ^ permalink raw reply [flat|nested] 4+ messages in thread
* [Bug target/17614] long double / -mfp-rounding-mode=d -mieee-with-inexact 2004-09-22 15:59 [Bug c/17614] New: Integer Division produces a Floating exception ppelissi at caramail dot com 2004-09-22 16:00 ` [Bug c/17614] long double / -mfp-rounding-mode=d ppelissi at caramail dot com 2004-09-22 17:32 ` [Bug target/17614] long double / -mfp-rounding-mode=d-mieee-with-inexact pinskia at gcc dot gnu dot org @ 2004-09-22 18:06 ` pinskia at gcc dot gnu dot org 2 siblings, 0 replies; 4+ messages in thread From: pinskia at gcc dot gnu dot org @ 2004-09-22 18:06 UTC (permalink / raw) To: gcc-bugs ------- 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 ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2004-09-22 18:06 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2004-09-22 15:59 [Bug c/17614] New: Integer Division produces a Floating exception ppelissi at caramail dot com 2004-09-22 16:00 ` [Bug c/17614] long double / -mfp-rounding-mode=d ppelissi at caramail dot com 2004-09-22 17:32 ` [Bug target/17614] long double / -mfp-rounding-mode=d-mieee-with-inexact pinskia at gcc dot gnu dot org 2004-09-22 18:06 ` [Bug target/17614] long double / -mfp-rounding-mode=d -mieee-with-inexact pinskia at gcc dot gnu dot org
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