Custom call frame description

[Mitar <mmitar at gmail dot com>]

Hi!

I am writing a simple compiler for a custom/learning language on the
ARM platform. It is written in Java and outputs assembler code which
is then assembled with GNU assembler. As sometimes things do not work
as planned I would like to be able to use gdb to debug them,
especially stack, but as I have a custom call frame format gdb is
unable to unwind/read a stack trace. I have tried to get through DWARF
specification but I could not really manage how to specify frame
format in a simple way. I have checked GCC's source code but I got
lost in DWARF versions. DWARF Tutorial was useful but had no examples
for call frame. So I am a bit lost how to proceed. What should I write
to a assembler file so that resulting object file would have a call
frame description? My compiler does not optimise anything and
everything (return addresses and arguments -  they are always passed
over the stack) are all nicely stored in the stack. So by reading
stack I could easily debug output of my compiler.

So I would ask for advice and/or some example of an assembler code for
DWARF call frame description. My frame looks like this (all values are
32 bit):

static link (frame pointer points here and where is return value
stored after current function call)
local variables (some number of them)
old frame pointer
return address
temporary variables (where I store registers when there is not enough of them)
function arguments for next call


Mitar