I think someone mentioned this before -- this still fails to apply CFI
to the asm files obtained via the .sub/SUBARCH system (see the rules
just above the ones you changed). Of course I don't really like
duplicating complex rules, and i386 has no SUBARCHs anyway, so perhaps
we could put off changing this if someone has an idea for how to
eliminate the extra rules for SUBARCHs when we overhaul the build
system...

This was intentional, but since it has come up so many times, I will add the (extraneous) rules for SUBARCHs.

I'd still like to check $CFLAGS in addition to $CFLAGS_AUTO, since
CFLAGS=-g is the usual way I ask for debug info. (I'm sorry I ever
added the --enable-debug option to configure. :)

OK, will do.

I haven't reviewed the awk script much at all, but as long as it seems
to work in practice I'm okay with committing it. One thing I would
like to ask though -- is it pretty robust against bad things happening
if it sees new asm constructs it's not expecting? I'd just like to
avoid regressions if we add new asm later, where it becomes necessary
to delay commits to asm in order to fix bugs in the CFI generation.

It passes all your asm through and simply adds debugging directives when it recognizes certain constructs. So in no case will it actually break the asm. The worst which will happen is that you will adjust the stack pointer in some obscure way that it doesn't recognize, no CFI directive will be added, and then a debugger will be unable to produce a stack trace at that point in the code. But this is no worse than what we have right now. Right now we don't do anything to help the debugger at all.

Thanks, AD