RTTR_OPTIMIZATION_TUNE doesnt work

[christianddietrich]

cmake -DCMAKE_BUILD_TYPE=Release -DRTTR_ENABLE_OPTIMIZATIONS=ON -DRTTR_OPTIMIZATION_TUNE=native -DRTTR_OPTIMIZATION_VECTOR_EXT=AVX2 -DBUILD_TESTING=OFF ..
make

ps aux | grep mtune:
/usr/lib/gcc/x86_64-linux-gnu/7/cc1plus -quiet -I /root/s25client/libs/s25main -I /root/s25client/external/libsiedler2/include -I /root/s25client/external/libutil/include -I /root/s25client/external/libendian/include -I /root/s25client/external/libutil/nowide/include -I /root/s25client/external/liblobby/include -I /root/s25client/external/mygettext/include -I /root/s25client/libs/common/include -I /root/s25client/libs/rttrConfig/src -I /root/s25client/libs/libGamedata -I /root/s25client/build/external/glad/include -I /root/s25client/libs/driver/include -I /root/s25client/external/libutil/utfcpp/source -I /root/s25client/libs/libsamplerate/include -I /root/s25client/external/libsamplerate/src -I /root/s25client/build/external/libsamplerate -imultiarch x86_64-linux-gnu -D_GNU_SOURCE -D BOOST_NOWIDE_USE_FILESYSTEM -D HAVE_STRUCT_TIMESPEC -D NDEBUG -isystem /root/s25client/external/lua/include -isystem /root/s25client/external/kaguya/include /root/s25client/libs/s25main/nodeObjs/noGrainfield.cpp -quiet -dumpbase noGrainfield.cpp -mfpmath=sse -mavx2 -mtune=generic -march=x86-64 -auxbase-strip CMakeFiles/s25Main.dir/nodeObjs/noGrainfield.cpp.o -O3 -Wall -Wextra -Werror -pedantic-errors -Wcast-qual -Wdisabled-optimization -Wfloat-conversion -Wformat-nonliteral -Wformat-security -Wformat=2 -Winit-self -Wlogical-op -Wmissing-declarations -Wmissing-field-initializers -Wsuggest-attribute=format -Wmissing-include-dirs -Wsuggest-attribute=noreturn -Wpacked -Wparentheses -Wpedantic -Wpointer-arith -Wstrict-aliasing=2 -Wundef -Wunused -Wunused-parameter -Wwrite-strings -Wno-unknown-pragmas -Wctor-dtor-privacy -Wnoexcept -Woverloaded-virtual -Wstrict-null-sentinel -Wsuggest-override -Wno-maybe-uninitialized -Wno-error=suggest-override -Wredundant-decls -std=c++14 -fno-strict-aliasing -fstack-protector-strong -o /tmp/ccwIsGaQ.s

gcc version 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1)

To be able to change the machine type would also be great. (eg. -march=native)

[Flamefire]

This is a bug due to CMake scoping rules. Fixed that locally but as it is in a submodule (libutil) it needs to wait for #1085.

Thanks for that, it is actually significant (potentially) for performance

To be able to change the machine type would also be great. (eg. -march=native)

RTTR_OPTIMIZATION_TUNE has a default setting computed by the target architecture. For march this is not feasible as the code would not run on lower machines. Just use -DCMAKE_CXX_FLAGS=-march=native

[stefson]

gcc-7.3.0 had some serious codegen bugs, where it messed up with -march=native and another one where it mixed avx2 instructions into -march=native, regardless of the cpu. You might want to doublecheck if your distro has the fixes backported to gcc-7.4.0, not sure if they were fixed by upstream. gcc-8.3.0 has them all fixed.