These are tests for instrumentation based profiling.  This specifically means
the -fprofile-instr-generate and -fprofile-instr-use driver flags.

Tests in this directory should usually test both:

  - the generation of instrumentation (-fprofile-instr-generate), and
  - the use of profile data from instrumented runs (-fprofile-instr-use).

In order to test -fprofile-instr-use without actually running an instrumented
program, .profdata files are checked into Inputs/.

The input source files must include a main function such that building with
-fprofile-instr-generate and running the resulting program generates the same
.profdata file that is consumed by the tests for -fprofile-instr-use.  Even
tests that only check -fprofile-instr-use should include such a main function,
so that profile data can be regenerated as the .profdata file format evolves.