On 2011.07.17 at 18:30 +0200, Richard Guenther wrote: > On Sun, Jul 17, 2011 at 1:30 PM, Eric Botcazou <ebotca...@adacore.com> wrote: > >> I have measured it at some point and IIRC it was about 10% slower > >> (comparing C bootstrap with C++ in stag1 languages with C++ bootstrap, > >> not sure if that included bootstrapping libstdc++ for the former). > > > > IMO acceptable now that the build time of libjava has been halved. > > Actually the penalty for using C++ was only 1.5%, that of bootstrapping C++ > and > libstdc++ was 15%. For reference:
I've tested the difference today on an average 4 CPU machine with 8GB RAM. This is the result of otherwise identical LTO+PGO builds: --enable-build-with-cxx make -j4 profiledbootstrap 3384.20s user 177.02s system 291% cpu 20:23.12 total <default> make -j4 profiledbootstrap 3011.03s user 144.30s system 297% cpu 17:41.59 total That's a ~15% increase in build time. (I couldn't test --enable-build-poststage1-with-cxx, because it doesn't seem to work with this configuration. Maybe the patch needs to be updated to also cover LTO or PGO builds?) Configured with: ../gcc/configure --prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.7.0 --includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.7.0/include --datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.7.0 --mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.7.0/man --infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.7.0/info --with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.7.0/include/g++-v4 --host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --disable-altivec --disable-fixed-point --without-ppl --without-cloog --enable-lto --enable-nls --without-included-gettext --with-system-zlib --disable-werror --with-gold --enable-secureplt --disable-multilib --enable-libmudflap --disable-libssp --enable-libgomp --enable-cld --with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.7.0/python --enable-checking=release --disable-libgcj --enable-languages=c,c++ --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --with-build-config=bootstrap-lto And built with: make -j4 BOOT_CFLAGS="-march=native -O2 -pipe" STAGE1_CFLAGS="-march=native -O2 -pipe" CFLAGS_FOR_TARGET="-march=native -O2 -pipe" profiledbootstrap -- Markus