-// Insert prolog code at the unique function entry point.
-// Insert epilog code at each function exit point.
-// InsertPrologEpilog invokes these only if the function is not compiled
-// with the leaf function optimization.
+// This is the SparcV9 target's own PrologEpilogInserter. It creates prolog and
+// epilog instructions for functions which have not been compiled using "leaf
+// function optimizations". These instructions include the SAVE and RESTORE
+// instructions used to rotate the SPARC register windows. Prologs are
+// attached to the unique function entry, and epilogs are attached to each
+// function exit.