Happen with gcc43 snapshot 20070105 (experimental). gcc configured with: ./..//gcc-4.3-20070105/configure --disable-nls --with-system-zlib --with-libiconv-prefix=/usr/local --with-gmp=/usr/local --program-suffix=43 --libdir=/usr/local/lib/gcc-4.3.0 --with-gxx-include-dir=/usr/local/lib/gcc-4.3.0/include/c++/ --infodir=/usr/local/info/gcc43 --disable-libgcj --prefix=/usr/local x86_64-portbld-freebsd6.2
$ time gcc43 -O3 -c f5.c -Wall user 8m0.834s max memory usage 1321 MB. It takes too long time and huge memory to compile, compared to gcc4.2 or -O2: $ time gcc42 -O3 -c f5.c user 0m0.575s $ time gcc43 -O2 -c f5.c -finline-functions -funswitch-loops -fgcse-after-reload user 0m0.602s And the memory usage is less than 10 MB. -- Summary: huge memory consumption with -O3 Product: gcc Version: 4.3.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: kcwu at csie dot org GCC build triplet: x86_64-portbld-freebsd6.2 GCC host triplet: x86_64-portbld-freebsd6.2 GCC target triplet: x86_64-portbld-freebsd6.2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30610