Date: Tue, 29 May 2007 22:29:54 -0700 (PDT) From: Steve Kargl <sgk@troutmask.apl.washington.edu> To: FreeBSD-gnats-submit@FreeBSD.org Subject: standards/113147: frexpf in libm has C aliasing issues with gcc 4.2 Message-ID: <200705300529.l4U5Ts3C008014@troutmask.apl.washington.edu> Resent-Message-ID: <200705300540.l4U5e2hn086410@freefall.freebsd.org>
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>Number: 113147
>Category: standards
>Synopsis: frexpf in libm has C aliasing issues with gcc 4.2
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-standards
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed May 30 05:40:02 GMT 2007
>Closed-Date:
>Last-Modified:
>Originator: Steve Kargl
>Release: FreeBSD 7.0-CURRENT amd64
>Organization:
apl/uw
>Environment:
System: FreeBSD troutmask.apl.washington.edu 7.0-CURRENT FreeBSD 7.0-CURRENT #4: Thu Apr 19 12:32:30 PDT 2007 kargl@troutmask.apl.washington.edu:/usr/obj/usr/src/sys/SPEW amd64
>Description:
Currently, libm must be built with -fno-strict-aliasing due
to undefined behavior according to the C standard. The
problem is is s_frexprf.c
>How-To-Repeat:
Build libm with -fstrict-aliasing in the CFLAGS.
>Fix:
(Watch for cut-&-paste tab corruption)
--- s_frexpf.c.orig Sat May 26 16:26:50 2007
+++ s_frexpf.c Mon May 28 17:55:48 2007
@@ -39,6 +39,6 @@
}
*eptr += (ix>>23)-126;
hx = (hx&0x807fffff)|0x3f000000;
- *(int*)&x = hx;
+ SET_FLOAT_WORD(x,hx);
return x;
}
>Release-Note:
>Audit-Trail:
>Unformatted:
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