TMSC320C6x port: return label is being deleted

Nick Ing-Simmons nick@ing-simmons.net
Mon Oct 4 13:37:00 GMT 2004


Graham Stott <graham.stott@btinternet.com> writes:
>> "
>You don't need/want all the stuff after after your emit_call_insn
>
>In your define_insn for your call you use something like.
>(define_insn "..."
>  []
>  ""
>{
>  rtx label = gen_label_rtx ();
>
>  output your call sequence
>  ..
>
>  now output the label
>  
>  return "";
>}
>
>See how the rest of the compiler doesn't know or care
>about these labels.

I don't know if Adrian's port does this but when I was at TI and 
playing with a GCC port of C6x I wanted to avoid "clever" output sections.
Reason was that C6x is a VLIW - so it can execute instructions in parallel.
So my port tried to make each 'insn' a one-cycle RISC-like one
(define_expand-ing as required).

Then there was a custom output pass that walked the RTL and collected 
RISC-like things into VLIW execute packets.
Multi-cycle things are a pain in such a scheme.
I haven't got my code anymore - I left it at TI.
But I seem to recall that my call define expanded 
into the load-return and the jump. And the jump had a (fake) dependancy 
on the return address register to keep them in right order.

 





>
>> 
>> Thanks,
>> Adrian
>>  
>
>Graham



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