Writing function calls in RTL

[qubits]

Hello everyone,
I want the compiler to call one of my functions when
it is generating RTL for tree expressions. For this I
need to 'emit' a function call into the code generated
so that it is called during program run-time. How does
one go about doing this? 
I looked at a function called 'emit_library_call' in
calls.c. But I'm not sure whether one can use this
function to 'emit' function calls into the generated
code. Please let me know about this.

I am also looking for some kind of documentation about
the RTL back-end. The documents by RMS: 'Using and
porting GCC' & 'GCC Internals' are excellent, but they
dont list which functions are to be used etc. and how
one goes about using functions to control RTL
generation. I have been 'grep-ing', but I would like
to know if there is some existing documentation :)
Any suggestions are welcome!

Thanks,
q.


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