You can display profiling information (i.e. information on how many times each line has been executed) for a source file by pressing the F9 key. You must have compiled the source file with /PROFILE. The numbers displayed down the right hand column give the number of times each line has been executed. You can also display profile information with the 'profile' command.
More than one source file can be compiled with /PROFILE. In addition the profile counts can be written to a file.