Date: Sun, 29 Apr 2007 00:00:13 -0000 From: Peter Jeremy <peterjeremy@optushome.com.au> To: FreeBSD-gnats-submit@FreeBSD.org Subject: amd64/112222: 32-bit libc incorrectly converts some FP numbers Message-ID: <200704282354.l3SNsflv002488@turion.vk2pj.dyndns.org> Resent-Message-ID: <200704290000.l3T00CfN068084@freefall.freebsd.org>
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>Number: 112222
>Category: amd64
>Synopsis: 32-bit libc incorrectly converts some FP numbers
>Confidential: no
>Severity: critical
>Priority: high
>Responsible: freebsd-amd64
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Sun Apr 29 00:00:12 GMT 2007
>Closed-Date:
>Last-Modified:
>Originator: Peter Jeremy
>Release: FreeBSD 6.2-STABLE amd64
>Organization:
n/a
>Environment:
System: FreeBSD turion.vk2pj.dyndns.org 6.2-STABLE FreeBSD 6.2-STABLE #25: Tue Jan 30 05:01:57 EST 2007 root@turion.vk2pj.dyndns.org:/usr/obj/usr/src/sys/turion amd64
>Description:
During testing of some 32-bit code on amd64, nonsense was printed
for some floating point conversions, eg ':e+22' instead of 1e+23
or ':e-07' instead of 1e-06.
Further testing has localised the problem to dtoa(), though it is
not yet clear whether the problem is in the source code, the
compiler or the 32-bit cross-build part of buildworld.
The problem only appears to affect numbers with a decimal fractional
part of 1 and decimal exponents of -307, -298, -283, -280, -278, -277,
-275, -274, -272, -271, -269, -268, -260, -258, -145, -96, -94, -93,
-88, -85, -82, -81, -80, -77, -76, -75, -74, -72, -71, -69, -67, -66,
-65, -64, -49, -40, -39, -36, -34, -29, -28, -24, -23, -20, -19, -16,
-14, -12, -11, -7, -6, +23, +24, +28, +29, +31, +35, +36, +38, +40,
+41, +42, +43, +46, +47, +48, +51, +52, +53, +55, +57, +59, +62, +65,
+66, +67, +68, +72, +73, +74, +77, +78, +79, +80, +82, +85, +86, +87,
+88, +89, +90, +94, +95, +96, +97, +98, +100, +103, +104, +108, +110,
+113, +114, +115, +116, +117, +121, +122, +129, +130, +132, +133, +136,
+137, +138, +139, +140, +141, +142, +143, +144, +145, +148, +149, +151,
+152, +153, +154, +155, +172, +174, +178, +182, +190, +191, +192, +193,
+198, +201, +205, +206, +207, +209, +216, +218, +221, +222, +223, +227,
+230, +243, +244, +246, +252, +262, +263, +267, +268, +271, +273, +275,
+277, +278, +283, +285, +288, +289, +290, +292, +294, +297, +299, +300,
+301, +302, +303, +306.
Linking against libc/gdtoa_dtoa.o compiled in an i386 environment
does not show the problem.
>How-To-Repeat:
echo 'main(){printf("%g %g %g\\n", 1e-24, 1e-7, 1e100);}' > x.c
cc -m32 x.c
./a.out
>Fix:
Unknown.
>Release-Note:
>Audit-Trail:
>Unformatted:
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