Difficulties byte-compiling very large .el file

[Aemon Cannon]

This is a re-post of a question I asked of gnu.emacs.help. Xah Lee
suggested I try this mailing list.
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I've been working on a project to create an elisp target for the ANTLR
parser-generator. Here's the project page:
http://github.com/aemoncannon/antlr-elisp/tree/experimental

The generated parser for ActionScript 3 is over 30k lines long and
fails to byte-compile with the message in Emacs 22:
as3_elispParser.el:31515:33:Error: Invalid character: 256, #o400,
#x100

..and this message in Emacs 23:
../test/grammars/as3_elispParser.el:31515:33:Error: Args out of range:
256, 0, 255

Here's the source in question: http://aemon.com/file_dump/as3_elispParser.el

If you're interested in trying to compile, you'll need:
http://github.com/aemoncannon/antlr-elisp/raw/c411f29743e3182523e0ad27a9384b6c4210d55e/src/runtime/ELisp/a3el-runtime.el

I don't think the error is actually related to the content of the
file, as there are no non-ascii characters in the file, and deleting
seemingly arbitrary chunks makes the error go away.

There are lots of "Warning: reference to free variable ...." warnings,
but I understand where those are coming from and I'm not worried about
them.

Bear in mind there are *lots* of macros being expanded. Most of the
forms with the prefix 'a3el' are macros.

Any ideas?