https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100347
--- Comment #14 from Iain Sandoe <iains at gcc dot gnu.org> --- (In reply to Erik Schnetter from comment #13) > The failing GCC 11.1.0 is built by Apple Clang 12.0.5 via Spack. Looking at > debug output, I see that Spack inserts a "-march=skylake" command line > option. (I was not aware of this before.) It does so by creating a compiler > wrapper (called "clang++" as well), which calls the actual compiler and adds > this (and some other) flags. > > I seem to recall having read somewhere that GCC's CPU detection code must be > built without any "-march=..." flag. well, the GCC config makes sensible default choices for CPU (if there's no --with-cpu=) - which is core2 mostly (so that the code should run anywhere). As of this moment the only machines I've got builds with --with-cpu= specify the correct CPU for the machine, so -march= isn't going to tell anything - except I can say for sure that it doesn't report x86_64): /src-local/gcc-master/configure --prefix=/opt/iains/x86_64-apple-darwin16/gcc-12-0-0d --build=x86_64-apple-darwin16 --with-sysroot=/Library/Developer/CommandLineTools/SDKs/MacOSX.sdk --enable-languages=all --with-cpu=corei7 --with-tune=skylake CC=x86_64-apple-darwin16-gcc CXX=x86_64-apple-darwin16-g++ $ ./gcc/xgcc -Bgcc -march=native -Q --help=target | grep march -march= skylake So that's reporting what was configures, but also what would be correct for the hardware - it hasn't overridden the configuration settings. can we get the output of "gcc -v" for the compiler that isn't working? If this is a compiler built without bootstrap, and the bootstrap compiler is clang, then that could be an unknown quantity. Production compilers should be bootstrapped.
