llvm dev - Apr 2018 - xtensa backend

Can you give me some insights to implement the windowed calling convention
in this xtensa backend :
https://github.com/afonso360/llvm-xtensa/tree/xtensa/lib/Target/Xtensa ?

For now, only the simpler CALL0 calling convention is implemented.

In order to implement the windowed calling convention, every routines must
start with the ENTRY instruction which increments the register window
pointer.

Do I have to manually insert this instruction during the PrologEpilog
phase, and how can I declare this instruction ?

Maxime
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On 4/19/2018 1:16 PM, Maxime BOURREAU via llvm-dev
wrote:
> Can you give me some insights to implement the windowed calling 
> convention in this xtensa backend : 
> https://github.com/afonso360/llvm-xtensa/tree/xtensa/lib/Target/Xtensa ?
Are these like SPARC register windows?  Have you looked at what the 
SPARC backend does?

-Eli

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