create separate recursive mutexes for each value map. The recursive-ness fixes the double-acquiring issue, which having one per ValueMap
lets us continue to maintain some concurrency.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73801 91177308-0d34-0410-b5e6-96231b3b80d8
gets involved, and we end up trying to recursively acquire a writer lock. The fix for this is slightly horrible,
and involves passing a boolean "locked" parameter around in Constants.cpp, but it's better than having locked and
unlocked versions of most of the code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73790 91177308-0d34-0410-b5e6-96231b3b80d8
