Date: Sun, 18 Jan 2004 13:03:56 -0800 From: Marcel Moolenaar <marcel@xcllnt.net> To: src-committers@FreeBSD.ORG, cvs-src@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/lib/libc/gdtoa Makefile.inc _hdtoa.c src/lib/libc/stdio vfprintf.c Message-ID: <20040118210356.GA82925@dhcp01.pn.xcllnt.net> In-Reply-To: <20040118103340.GA44149@VARK.homeunix.com> References: <200401181032.i0IAWoMh012953@repoman.freebsd.org> <20040118103340.GA44149@VARK.homeunix.com>
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On Sun, Jan 18, 2004 at 02:33:40AM -0800, David Schultz wrote:
> Any suggestions or bug reports involving this code are welcome, but
> please note the following caveats:
>
> - strtod() has some bugs involving parsing hexadecimal
> floating-point numbers, which should be fixed in the
> next gdtoa import (to come shortly). Until then, be
> aware that numbers parsed with strtod() may not be
> output as expected because they were not parsed correctly
> in the first place. In particular, don't specify too
> many digits in the significand for subnormals, and
> don't expect underflow to zero to work correctly.
Currently stdtod() is causing a SIGFPE on ia64 for a kernel build.
This started when obrien@ added the following code to kern.post.mk:
+emu10k1-alsa%diked.h: $S/gnu/dev/sound/pci/emu10k1-alsa.h
+ grep -v '#include' ${.OODATE} | ${CC} -E -D__KERNEL__ -dM - \
+ | awk -F"[ (]" '/define/ \
+ { print "#ifndef " $$2 ; print ; print "#endif" }' \
+ >${.TARGET}
+.if !exists(${.OBJDIR}/.depend)
+_kernel-depend: emu10k1-alsa%diked.h
+.endif
The problem is that awk(1) gets a SIGFPE unconditionally. I haven't
spent too much time on it yet, but I get the following in the gdb(1):
Program received signal SIGFPE, Arithmetic exception.
0x40000000000553d2 in strtod (s00=0x600000000001c02d "e-324",
se=0x9fffffffffffe6f0) at gdtoa_strtod.c:938
938 dval(rv) *= dval(rv0);
(gdb)
0x40000000000553d0 <strtod+16224>: [MFB] nop.m 0x0
0x40000000000553d1 <strtod+16225>: fmpy.d.s0 f6=f7,f6
0x40000000000553d2 <strtod+16226>: nop.b 0x0;;
(gdb) info reg f6 f7
f6 8.8817841970012523233890533447265625e-16 (raw 0x000000000000fbcd8000000000000000)
f7 4.0083367200179455559922161027003241e-292 (raw 0x000000000000fc378000000000000000)
(gdb) Erroneous arithmetic operation.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Very suspicious gdb(1) error. Don't trust the register values.
If you're interested in analyzing this, I have the above trigger case
in ~marcel/strtod on @FreeBSD.org. The awk(1) executable in that
directory has full debugging information (including libc). Run as:
./awk -F"[ (]" '/define/ { print "#ifndef " $2 ; print ; print "#endif" }' < awk.in
FYI,
--
Marcel Moolenaar USPA: A-39004 marcel@xcllnt.net
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