Barretenberg build failure on Apple M1 processor #66
Description
Attempting to compile barretenberg on an apple M1 currently fails during cmake configuration and fixing it seems non-trivial.
First, configuring cmake for barretenberg currently gives an error due to M1s storing binaries at different locations than intel-based macs:
--- stderr
CMake Error at CMakeLists.txt:9 (project):
The CMAKE_CXX_COMPILER:
/usr/local/opt/llvm/bin/clang++
is not a full path to an existing compiler tool.
Tell CMake where to find the compiler by setting either the environment
variable "CXX" or the CMake cache entry CMAKE_CXX_COMPILER to the full path
to the compiler, or to the compiler name if it is in the PATH.
CMake Error at CMakeLists.txt:9 (project):
The CMAKE_C_COMPILER:
/usr/local/opt/llvm/bin/clang
is not a full path to an existing compiler tool.
Tell CMake where to find the compiler by setting either the environment
variable "CC" or the CMake cache entry CMAKE_C_COMPILER to the full path to
the compiler, or to the compiler name if it is in the PATH.
On my system, the path for apple clang is at /usr/bin/clang instead. Using this gives an error for -fopenmp not being supported however. Using the homebrew clang at /opt/homebrew/opt/llvm/bin/clang works instead. Then changing barretenberg/cmake/toolchains/x86_64-apple-clang.cmake from
set(CMAKE_CXX_COMPILER "/usr/local/opt/llvm/bin/clang++")
set(CMAKE_C_COMPILER "/usr/local/opt/llvm/bin/clang")to
set(CMAKE_C_COMPILER $ENV{CC})
set(CMAKE_CXX_COMPILER $ENV{CXX})works as a quick band-aid to the problem, though perhaps cmake should detect an M1 processor and defer to a new arm64-apple-clang.cmake file instead. Running cmake . again from there we run into a similar error to #65:
CMake Error at CMakeLists.txt:46 (include):
include could not find load file:
cmake/build.cmake
For some reason, this last error isn't present on the branch kw/noir-dsl-mac. Continuing on that branch, building via make fails due to clang (13.0.0) not supporting -march=native on an apple M1:
$ make
[ 1%] Building CXX object src/aztec/env/CMakeFiles/env_objects.dir/logstr.cpp.o
clang-13: fatal error: the clang compiler does not support '-march=native'
make[2]: *** [src/aztec/env/CMakeFiles/env_objects.dir/logstr.cpp.o] Error 1
make[1]: *** [src/aztec/env/CMakeFiles/env_objects.dir/all] Error 2
make: *** [all] Error 2
exit 2
arch.cmake can be patched up a bit to get past this:
include(CheckCCompilerFlag)
check_c_compiler_flag("-march=native" marchNativeSupported)
if(NOT WASM AND marchNativeSupported)
add_compile_options(-march=native)
endif()After which make gives a different error since libomp is installed to a different directory (/opt/homebrew/lib/libomp.a) instead of the expected:
make[2]: *** No rule to make target `/usr/local/lib/libomp.a', needed by `src/aztec/numeric/numeric_tests'. Stop.
After manually creating a link for the library to the expected location the build fails in a dependency:
/Users/.../barretenberg/_deps/benchmark-src/src/complexity.cc:85:10: error: variable 'sigma_gn' set but not used [-Werror,-Wunused-but-set-variable]
double sigma_gn = 0.0;
^
This error is fatal unless we build in debug mode instead. Compiling in debug gets us a bit further but fails here instead:
/Users/.../barretenberg/src/aztec/ecc/curves/bn254/scalar_multiplication/../../../groups/group_impl_asm.tcc:107:30: fatal error: unknown token in expression
__asm__ __volatile__("xorq %%r8, %%r8 \n\t"
^
<inline asm>:1:7: note: instantiated into assembly here
xorq %r8, %r8
^
1 error generated.