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.