Prototype and playground for generating stack maps to garbage-collected objects using clang/llvm infrastructure.

Design doc: https://bit.ly/chromium-stack-maps

Building and Running Tests:

1. Build the gc libary

mkdir gc/build/ && cd gc/build

cmake ../ && make

2. Build the LLVM passes:

mkdir ../../build/ && cd ../../build/

cmake ../ && make all

3. Run the tests (from stack_maps/tests/)

./test.py <path_to_chromium_llvm_bin_dir> ../gc/build/libGC.a \ ../build/IdentifySafepoints/libLLVMIdentifySafepointsPass.so \ ../build/RegisterGcFunctionsPass.so