On Tue, May 28, 2019 at 10:00 PM Stefan Ring <stefanrin@xxxxxxxxx> wrote: > > On Mon, May 27, 2019 at 1:49 AM Tadeus Prastowo > <tadeus.prastowo@xxxxxxxx> wrote: > > Once debuild is done, I installed the aforementioned DEB files and > > found out that the installed /usr/bin/g++-9 still compiles faster as > > before. So, I have failed to identify the factor in the PPA build > > process that makes the resulting compiler faster than mine, which was > > built from the release tarball using configure & make. Any idea how > > to find the factor that results in a faster compiler? Is it really > > the build process or the way the resulting compiler is installed that > > gives the speed up? For example, does symbol stripping have any > > effect (I tried already to strip all symbols out of the executables > > found in my GCC-9 installation with `strip -s' but to no avail)? > > Perhaps some compiler libraries are installed in a particular way in > > Ubuntu? > > I guess the Ubuntu package uses "make profiledbootstrap", which you > don’t get (IIRC) when just issuing "make". Yes, that is true, but that did not ring my bell. Thank you very much for ringing the bell for me, quoting https://gcc.gnu.org/install/build.html: It is possible to use profile feedback to optimize the compiler itself. This should result in a faster compiler binary. Experiments done on x86 using gcc 3.3 showed approximately 7 percent speedup on compiling C programs. To bootstrap the compiler with profile feedback, use make profiledbootstrap. I will give it a try and report it back. -- Best regards, Tadeus
