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[Bug rtl-optimization/323] optimized code gives strange floating point results
- From: "sliwa at cft dot edu dot pl" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 3 Oct 2004 15:52:20 -0000
- Subject: [Bug rtl-optimization/323] optimized code gives strange floating point results
- References: <20000614141601.323.mirtich@merl.com>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From sliwa at cft dot edu dot pl 2004-10-03 15:52 -------
Excessive precision should be discarded before performing any comparison. It is
done e.g. by the Intel fortran compiler. -ffloat-store rounds only the values
stored in a variable, and in some situations may trigger instead of suppressing
the bug. Existing numerical software packages (e.g. LAPACK and SLATEC fortran
libraries) fail their tests with gcc just due to this issue.
So it is a bug, even if almost all other compilers reproduce it.
If you refer me to a FAQ on numerical analysis, please note that the FAQ states
things as they are, and not as they should be.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=323