apaszke / ffi-experimental

Code generation / FFI binding experiments using libtorch 1.0

Experimental Libtorch 1.0 FFI

Experimental work on next-gen ffi bindings into the c++ libtorch library in preparation for 0.0.2 which targets the 1.0 backend.

General approach:

• Use generated Declarations.yaml spec instead of header parsing for code generation.
• Try inline-cpp functionality to bind the C++ API instead of the C API. Benchmark potential template haskell overhead vs. code generating C wrappers for C++ functions.

libtorch dependency retrieval and testing

libtorch-test/ and deps/ have scripts that retrieve libtorch and mkl-dnn library dependencies and builds/tests them using a minimal example.

To build:

cd libtorch-test
make

The makefile pulls in libtorch + mkl-dnn (not included in libtorch) prebuilt shared library files.

If the dependencies are retrieved and built successfully, you should see at the end of the build process the expected output of a random 2x2 matrix (exact values may differ):

...
[ 50%] Building CXX object CMakeFiles/libtorch-test.dir/cpptest.cpp.o
[100%] Linking CXX executable libtorch-test
[100%] Built target libtorch-test
export LD_LIBRARY_PATH=/Users/huanga13/projects-personal/ffi-experimental/libtorch-test/deps/mklml_mac_2019.0.1.20181227/lib:/Users/huanga13/projects-personal/ffi-experimental/libtorch-test/deps/libtorch/lib
source ./set-dyld-path.sh ; cd build ; ./libtorch-test
 0.5790  0.5507  0.6433
 0.9908  0.6380  0.3997
[ Variable[CPUFloatType]{2,3} ]

yaml -> binding codegen (WIP)

To run:

stack build codegen
stack exec codegen-exe

To get CLI options:

stack exec codegen-exe -- --help

ffi testing (WIP)

To run without repl:

#Download libtorch-binary
pushd deps
./get-deps.sh
popd

#Set environment variable(LD_LIBRARY_PATH)
source setenv

#Build and test with stack
stack test

#Build and test with cabal
#setup cabal.project.freeze using stackage, extra-include-dirs and extra-lib-dirs for cabal
./setup-cabal.sh
cabal new-test all

To run (currently works in the repl):

stack ghci --ghc-options='-fobject-code'  ffi
...
Prelude Main> main
Hello torch!
 0.2401  0.0901  0.9807
 0.9168  0.3757  0.4029
[ Variable[CPUFloatType]{2,3} ]
 1  1
 1  1
[ Variable[CPUFloatType]{2,2} ]
 0.1232  1.5721
 0.5392  0.2395
[ Variable[CPUFloatType]{2,2} ]
 1.1232  2.5721
 1.5392  1.2395
[ Variable[CPUFloatType]{2,2} ]
Prelude Main>

Contributions

Contributions/PRs are welcome.