Andrew Ng

[Support] Fix TempFile::discard to not leave behind temporary files

[TableGen] Make OpcodeMappings sort comparator deterministic NFCI

[Support] MemoryBlock size should reflect the requested size

[benchmark] Disable CMake get_git_version

Well as no one has looked into this, I've taken a look and I think I have a fix and some minor improvements too. I think I'll need to test it a bit longer, but so far so good. It certainly does not deadlock in the various test cases and mostly fixes LLD. However, there are still LLD deadlocks when running the LLD lit tests and I believe that these are actually related to LLD exit causing deadlock (something else that I've had the misfortune of looking at).

I have run into this issue just recently, so it is still a problem! I've done some investigation and it appears to be related to the use of std::condition_variable in "lib/Support/Parallel.cpp" of LLVM. In this file, there is a use of notify_one() which is called without the lock for the mutex used in the associated wait(). This is valid code according to the specification of std::condition_variable. However, the default MinGW libstdc++ runtine is built using POSIX threading and thus the std::condition_variable...