Improve docs/comments

Author: saethlin

src/concurrency/thread.rs

@@ -1019,7 +1019,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
             // immediately. In our interpreter loop we try to consult this value often, but if for
             // whatever reason we don't get to that check or the cleanup we do upon finding that
             // this bool has become true takes a long time, the exit here will promptly exit the
-            // process.
+            // process on the second Ctrl-C.
             if SIGNALED.swap(true, Relaxed) {
                 std::process::exit(1);
             }

src/machine.rs

@@ -714,8 +714,12 @@ impl<'mir, 'tcx> MiriMachine<'mir, 'tcx> {
         def_id.is_local() || self.local_crates.contains(&def_id.krate)
     }
 
-    /// Called when the interpreter is going to shut down abnormally, such as due to a ctrl+c.
+    /// Called when the interpreter is going to shut down abnormally, such as due to a Ctrl-C.
     pub(crate) fn handle_abnormal_termination(&mut self) {
+        // All strings in the profile data are stored in a single string table which is not
+        // written to disk until the profiler is dropped. If the interpreter exits without dropping
+        // the profiler, it is not possible to interpret the profile data and all measureme tools
+        // will panic when given the file.
         drop(self.profiler.take());
     }
 }