Using profile-guided optimization (PGO)
gcc -O3 -march=native -pg -fprofile-generate ...
# Run a benchmark or program's typical load
gcc -O3 -march=native -fprofile-use ...
Address sanitizers
Use GCC/clang option -fsanitize=, with arguments:
- address
- leak
- thread
- undefined
Performance-related options
Use -march=native when a binary will never leave the machine upon which it is compiled. To determine which arch will be used, run:
gcc -c -Q -march=native --help=target | grep march
You can see what other performance-related options will be set by examining the output of that gcc command.
If a machine has sufficient amounts of RAM, -pipe can make the compilation process faster.
In short:
export CFLAGS="-O3 -march=native -pipe"
export CXXFLAGS=$CFLAGS
Check compiler preprocessor defines
# E.g. check for the version of OpenMP supported
echo | cpp -fopenmp -dM | grep -i open
#define _OPENMP 200805
Compiling gcc
Download gcc tarball, run contrib/download_prerequisites script to download external libraries to build as part of gcc.
./configure --prefix=/opt/gcc-custom --disable-multilib --disable-libada --enable-languages=c,c++
Static compilation
Insane Coding: Creating portable Linux binaries. Use -static-libgcc -static-libstdc++ to include compiler support libraries.
Linux distribution binary compatibility. Discusses glibc symbol versioning, and using the .symver directive to select a version of a functionl.
https://blogs.gnome.org/tvb/2013/12/14/application-bundles-revisited/ Application Bundles Revisited – Tristan's World. Discusses a vala script that will create a header file targeting an older glibc.
https://github.com/probonopd/AppImageKit/tree/fc6b9c5e896e4408ffd52a41dcb7a0be3149f74e/LibcWrapGenerator. Above script w/ CMake integration.
ABI
What gcc versions are available in Red Hat Enterprise Linux? - Red Hat Customer Portal: versions of GCC available on various RHEL/CentOS versions, including the Redhat Developer Toolset.
GCC 5.1 dual ABI w.r.t. std::string and std::list: https://gcc.gnu.org/onlinedocs/libstdc%2B%2B/manual/using_dual_abi.html. Can be enabled by default in GCC by using --with-default-libstdcxx-abi=c++98
Interesting reading
Performance benchmarks w/ calling DSO libraries: compares DSOs w/ Position Independent Code (PIC) enabled, static libraries, and directly calling functions.
ABI tracking: https://abi-laboratory.pro/tracker/timeline/glibc/ and https://github.com/lvc/abi-tracker
New features
Static analysis in GCC 10 describes the new -fanalyzer option.
-flto=$(nproc) for LTO. -fwhole-program if program fits into a single compilation unit.
