src/compiler-rt/test/cfi/README.txt

   1 The tests in this directory use a common convention for exercising the
   2 functionality associated with bit sets of different sizes. When certain
   3 macros are defined the tests instantiate classes that force the bit sets
   4 to be of certain sizes.
   5
   6 - B32 forces 32-bit bit sets.
   7 - B64 forces 64-bit bit sets.
   8 - BM forces memory bit sets.