@command{redo-ifchange}'s @option{-f} option forces each target
rebuilding. Comparing to @command{redo}, it will parallelize the
process.
+@item
+ Inode's number is also stored as dependency information, just to
+ prevent possible @code{ctime} collision of two files.
+@item
+ Performance optimization: do not use target's temporary output file
+ at all, if its hash equals to already existing target's one. Just
+ touch existing target file instead.
@end itemize
@anchor{Release 1_22_0}