See testcase.
# gcc twofish.c;./a.out
Iterations/sec: 63252
# gcc -Os twofish.c;./a.out
Iterations/sec: 45544
# gcc -O2 twofish.c;./a.out
Iterations/sec: 40192
# gcc -v
Reading specs from
/.share/usr/app/gcc-3.4.3/bin/../lib/gcc/i386-pc-linux-gnu/3.4.3/specs
Configured with: ../gcc-3.4.3/configure --prefix=/usr/app/gcc-3.4.3
--exec-prefix=/usr/app/gcc-3.4.3 --bindir=/usr/bin --sbindir=/usr/sbin
--libexecdir=/usr/app/gcc-3.4.3/libexec --datadir=/usr/app/gcc-3.4.3/share
--sysconfdir=/etc --sharedstatedir=/usr/app/gcc-3.4.3/var/com
--localstatedir=/usr/app/gcc-3.4.3/var --libdir=/usr/lib
--includedir=/usr/include --infodir=/usr/info --mandir=/usr/man
--with-slibdir=/usr/app/gcc-3.4.3/lib --with-local-prefix=/usr/local
--with-gxx-include-dir=/usr/app/gcc-3.4.3/include/g++-v3
--enable-languages=c,c++ --with-system-zlib --disable-nls --enable-threads=posix
i386-pc-linux-gnu
Thread model: posix
gcc version 3.4.3
--
Summary: Optimized code is much slower than non-optimized
Product: gcc
Version: 3.4.3
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: rtl-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: vda at port dot imtp dot ilyichevsk dot odessa dot ua
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: i386-pc-linux-gnu
GCC host triplet: i386-pc-linux-gnu
GCC target triplet: i386-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21147
