Date: Fri, 5 Jul 2002 04:26:51 +0200 (CEST) From: Dan Lukes <dan@obluda.cz> To: FreeBSD-gnats-submit@FreeBSD.org Subject: bin/40209: __dtoa broken with -O2 or -O3 optimisation Message-ID: <200207050226.g652QpV3013194@xkulesh.vol.cz>
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>Number: 40209
>Category: bin
>Synopsis: __dtoa broken with -O2 or -O3 optimisation
>Confidential: no
>Severity: serious
>Priority: high
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Jul 04 20:10:02 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: Dan Lukes
>Release: FreeBSD 5.0-CURRENT i386
>Organization:
Obludarium
>Environment:
src/lib/libc/stdlib/strtod.c,v 1.21 2002/05/28 16:59:40
gcc version 3.1 [FreeBSD] 20020509 (prerelease)
>Description:
when you compile libc (or stdlib/strtod.c at least) with -O3 or -O2
then __dtoa is broken. It cause printf malfunction for [eEfFgG] conversions
and has huge impact on several system utilities
worse scenario - as it damage awk used during buildworld, other unexpected
and not so easy trackable problems may occur because some utilities are
build from damaged sources
It is very dangerous as it doesn't render system unusable
(awk's damaged sources cause some warnings only during buildworld).
>How-To-Repeat:
compile libc with -O2 or -O3
compile and execute
printf("'%e' '%f' '%g'\n",(double)10,(double)10,(double)10);
you will get
':.000000' ':.000000e+00' ':'
It seems to be gcc's optimization problem only.
NOTE:
__dtoa's spec_case variable is used uninitialised when mode={8,9}
spec_case is initialised on lines 2252 and 2254 for modes 0,1,4,5
then it is referenced on 2316 when leftright!=0 e.g.
for mode 0,1,4,5,8,9 =>
=> for mode 8,9 spec_case referenced unitinialised
NOTE 2:
actual 4_RELENG code has no problem even with optimised libc
>Fix:
I can't present real fix.
workaround: Don't put -O2 or -O3 into /etc/make.conf's CFLAGS
>Release-Note:
>Audit-Trail:
>Unformatted:
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