Put an object file or archive that exports memcpy into a subdirectory compiler-rt/. Then run
zig build`which will build a copy of the benchmark executable for each file in compiler-rt/. Note that this
repo's build.zig will blindly try to build benchmarks for all files in compiler-rt/ so make sure
they all match the native target (or the one passed with -Dtarget). Benchmarks are always built in
ReleaseFast mode so you probably also want the objects in compiler-rt/ to have been built in
ReleaseFast mode.
The simplest way to get a suitable object is to modify the Zig compiler-rt source code and then run
zig build-obj lib/compiler-rt.zig -OReleaseFast. If there are no files in compiler-rt/, a
version of the benchmark will be built with the invoking compiler's memcpy.
For building multiple versions of compiler-rt at once, there are convenience scripts
build-commits.sh and build-matrix.sh in the tools/ directory. Copy these into a git checkout
of the Zig compiler repo and run them to build lib/compiler-rt.zig against multiple commits at
once. They both require a path to a Zig compiler and a file containing a newline-separated list of
commits (they are passed directly to git checkout). build-matrix.sh additionally requires a
target triple, a file containing a newline-separated list of arguments for -mcpu and an
optimization mode and will build compiler-rt for the Cartesian product of the specified commits
and CPUs.
Both build-commits.sh and build-matrix.sh places object files in a subdirectory call
compiler-rt-commits this directory can be moved/copied to the compiler-rt directory in this repo
in order to build the benchmarks.
To run the benchmarks there are convenience scripts generate-distrib-data.fish and
generate-avg-data.fish to run the distrib and average benchmarks respectively. Run them to get
a simple usage message. They both require an EXE_FILE argument, which must be a newline-separated
list of executables in zig-out/bin/ (e.g. you can get one with ls zig-out/bin/ > exe-list).
generate-avg-data.fish also requires a LENGTH_FILE which is a newline-separated list of copy
lengths to benchmark.
If it's inconvenient that there are fish scripts feel to raise an issue or PR more portable scripts.