AddressSanitizer and ThreadSanitizer (https://github.com/google/sanitizers) are projects initially developed by Google Inc. Both tools consist of a compiler module and a run-time library. The sources of the run-time library for these projects are hosted at https://github.com/llvm/llvm-project in the following directories: compiler-rt/include/sanitizer compiler-rt/lib/sanitizer_common compiler-rt/lib/interception compiler-rt/lib/asan compiler-rt/lib/tsan compiler-rt/lib/lsan compiler-rt/lib/ubsan compiler-rt/lib/hwasan Trivial and urgent fixes (portability, build fixes, etc.) may go directly to the GCC tree. All non-trivial changes, functionality improvements, etc. should go through the upstream tree first and then be merged back to the GCC tree. The merges from upstream should be done with the aid of the merge.sh script; it will also update the file MERGE to contain the upstream revision we merged with.