Add ARM and noASM implementation for Fr

[nixw4]

Mainlining of changes done in 0xPolygonID/witnesscalc.

Allows building c++ witness calc as a shared/static lib with assembly optimizations for x86_64, & arm64 (and without in pure cpp, so potentially could be compiled for other architectures) and for Linux, MacOS, iOS & Android.

[olomix]

Maybe it would be reasonable to create a readme file inside *_cpp directory with instruction on how to build it?
Right now, I'm trying to build a C++ witness calculator and I'm failing :(. What I'm doing..

1. Create a simple circuit2.circom file with following content:

pragma circom 2.0.0;

template Multiplier2(){
   //Declaration of signals
   signal input in1;
   signal input in2;
   signal output out;
   out <== in1 * in2;
}

component main = Multiplier2();

2. circom -c circuit2.circom
3. cd circuit2_cpp && mkdir build && cd build
4. cmake ..
5. Get the following error:

Building for
CMAKE_HOST_SYSTEM_NAME=Darwin
CMAKE_SYSTEM_NAME=
ARCH=x86_64
-- The CXX compiler identification is AppleClang 15.0.0.15000309
-- The ASM compiler identification is AppleClang
-- Found assembler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
USE_ASM=ON
CIRCUIT_NAME=circuit
HAS_PARALLELISM=OFF
CMAKE_CROSSCOMPILING=FALSE
-- Configuring done (0.2s)
CMake Error at CMakeLists.txt:90 (add_library):
  Cannot find source file:

    circuit.cpp

  Tried extensions .c .C .c++ .cc .cpp .cxx .cu .mpp .m .M .mm .ixx .cppm
  .ccm .cxxm .c++m .h .hh .h++ .hm .hpp .hxx .in .txx .f .F .for .f77 .f90
  .f95 .f03 .hip .ispc


CMake Error at CMakeLists.txt:90 (add_library):
  No SOURCES given to target: witnesscalc_circuit


CMake Error at CMakeLists.txt:91 (add_library):
  No SOURCES given to target: witnesscalc_circuitStatic

[OBrezhniev]

Use scripts from makefile instead of running cmake directly.

[diega]

Is there any chance this could be considered for merging? I tried building my circuit using cmake .. -DUSE_ASM=NO -DCIRCUIT_NAME=circuit_name and I ended up having problems linking to gmp like:

fr_raw_generic.cpp:14:22: error: no matching function for call to '__gmpn_add_n'

I had to add the following to CMakeLists.txt:

find_library(GMP_LIBRARIES gmp REQUIRED)
get_filename_component(GMP_DIR ${GMP_LIBRARIES} DIRECTORY)
find_path(GMP_INCLUDE_DIR gmp.h REQUIRED)
include_directories(${GMP_INCLUDE_DIR})
[...]
target_link_libraries(${CIRCUIT_EXECUTABLE} ${GMP_LIBRARIES})