The non-HD client appears to have been compiled with javac 1.1 or 1.2,
which compiles synchronized blocks differently to modern versions of
Java. For example, it uses a single try/catch block (modern versions use
two, the latter of which is recursive), subroutines (modern versions do
not) and the range of the try block is narrower.
Fernflower doesn't understand this old style of bytecode, and produces
empty synchronized blocks that do not cover the correct range.
The MONITORENTER sequence is also slightly different: it uses
ASTORE ALOAD MONITORENTER after pushing the monitor variable, rather
than DUP ASTORE MONITORENTER. This doesn't break Fernflower, but does
make it introduce a pointless assignment to a variable only used in the
synchronized() statement, rather than inlining the expression.
This commit introduces a transformer which fixes up Java 1.1-style
synchronized blocks just enough for Fernflower to be able to decompile
them cleanly. (It doesn't add a recursive try/catch, as Fernflower
ignores them.)
Signed-off-by: Graham <gpe@openrs2.dev>
Graham