[llvm-dev] How to add new AVR targets?

[Dylan McKay via llvm-dev]

Hey Wilhelm,

This should be possible by editing the 'AVRDevices.td' [1]TableGen
definitions to add an entry for the newer chip types. You will need to
instruct LLVM which features are available on the chip (such as extended
LPM support), cross referencing with the instruction set manual for the AVR
MCU you're adding to figure out what is allowed and what is not.

If there are newer instructions not yet supported by the AVR backend, or if
their are device-specific constraints not already handled by the backend in
its AVRDevices feature declarations, then you will need to either extend
the backend to support it, or declare the chip with a lower level of
support than is strictly required as a workaround.

Then after that, it should be possible to recompile the backend and target
the new chip type with 'llc -march=avr -mcpu=tiny1614'. for example.


   - [1] -
   https://github.com/llvm/llvm-project/blob/96fdc65dc4b19944079fa7f61ea52e4e0f999985/llvm/lib/Target/AVR/AVRDevices.td#L255


Regards,
Dylan


On Wed, Mar 4, 2020 at 10:19 PM Wilhelm Meier via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> I'm beginning to use the AVR backend. I ran into the problem, that newer
> (tiny1, mega0) µC as a tiny1614 are not supported. How do I add these to
> the AVR backend?
>
> Thanks!
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> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
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