Date: Tue, 13 May 2003 09:10:08 -0700 (PDT) From: Mikhail Teterin <Mikhail.Teterin@murex.com> To: freebsd-bugs@FreeBSD.org Subject: Re: bin/43299: march=pentium4 miscompiles msun/src/e_pow.c Message-ID: <200305131610.h4DGA8vx007871@freefall.freebsd.org>
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The following reply was made to PR bin/43299; it has been noted by GNATS. From: Mikhail Teterin <Mikhail.Teterin@murex.com> To: freebsd-gnats-submit@FreeBSD.org Cc: bde@FreeBSD.org Subject: Re: bin/43299: march=pentium4 miscompiles msun/src/e_pow.c Date: Mon, 12 May 2003 14:26:35 -0400 The problem with our libm (msun) vs. gcc-3 is reproduceable on Linux: (Note, FreeBSD's /usr is mounted as /misha on the Linux machine) mteterin@nylinux:lib/msun/src (982) cc -v Reading specs from /usr/lib/gcc-lib/i386-redhat-linux/3.2/specs Configured with: ../configure --prefix=/usr --mandir=/usr/share/man --infodir=/usr/share/info --enable-shared --enable-threads=posix --disable-checking --host=i386-redhat-linux --with-system-zlib --enable-__cxa_atexit Thread model: posix gcc version 3.2 20020903 (Red Hat Linux 8.0 3.2-7) mteterin@nylinux:lib/msun/src (983) cc -O -march=pentium3 -I- -I. -I/misha/src/include -I/misha/src/sys -I/misha/obj/misha/src/i386/usr/include e_pow.c t.c e_sqrt.c -D__generic___ieee754_sqrt=__ieee754_sqrt mteterin@nylinux:lib/msun/src (984) ./a.out 2^2.1 is 4.28709 mteterin@nylinux:lib/msun/src (985) cc -O -march=pentium4 -I- -I. -I/misha/src/include -I/misha/src/sys -I/misha/obj/misha/src/i386/usr/include e_pow.c t.c e_sqrt.c -D__generic___ieee754_sqrt=__ieee754_sqrt mteterin@nylinux:lib/msun/src (986) ./a.out 2^2.1 is 0 As can be seen above, using pentium3 produces the correct result, while pentium4 produces the incorrect 0. We can, pretty much, rule out a kernel problem in handling MMX/SSE. Which is it -- our __ieee754_pow or the gcc? -mi
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