I had a workspace with a successful build.
I then modified a source file, src/share/classes/java/util/JumboEnumSet.java,
did "cd make; make all", but the behavior did not change.

Why?

 $ find -name JumboEnumSet.class -ls
 51626 5 -rw-r--r-- 1 mb29450 green 4694 Jan 25 23:23 ./solaris-sparc/tmp/java/java.lang/library/newclasses/java/util/JumboEnumSet.class
 55354 5 -rw-r--r-- 1 mb29450 green 4674 Jan 16 04:14 ./solaris-sparc/tmp/sun/com.sun.tools.javac/newjavac/newclasses/java/util/JumboEnumSet.class
 22650 5 -rw-r--r-- 1 mb29450 green 4674 Jan 16 04:14 ./solaris-sparc/classes/java/util/JumboEnumSet.class

There's a new .class file, but the old one in classes has not been replaced.