llvm dev - Sep 2017 - TableGen : Difference between CodeEmitter and InstrInfo

Hello All,

I have created a file Instr.td which describes instructions for a new
assembly language.I would like to create a new  TableGen Backend by using
either of the two mentioned above backends so that i am able to retrieve
(print ,at least ) some info about the instructions such as Modifier
list,Constraints etc . I am confused between the above 2 backend's and find
them very similar.

1)Can please know the difference between the two , as they seem very similar
2)Which one will be the better backend to use to solve my above described
problem?


-Thanks
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In short, InstrInfo generates information about instructions 
(properties, etc) that is relevant to "MachineInstr". This information
contains data that the codegen passes use. I'm assuming that by 
CodeEmitter you mean the MC code emitter. MC refers to "machine code, 
i.e. the instructions encoded into the binary form. This is used to emit 
the final code into an object file.
Normally a new LLVM target will need both sets of data, but if you are 
only implementing an assembler, you may get away without having to 
generate the "instr info" part.

-Krzysztof

On 9/7/2017 1:00 AM, Sahil Chitnis via llvm-dev wrote:
> Hello All,
> 
> I have created a file Instr.td which describes instructions for a new 
> assembly language.I would like to create a new  TableGen Backend by 
> using either of the two mentioned above backends so that i am able to 
> retrieve (print ,at least ) some info about the instructions such as 
> Modifier list,Constraints etc . I am confused between the above 2 
> backend's and find them very similar.
> 
> 1)Can please know the difference between the two , as they seem very
similar
> 2)Which one will be the better backend to use to solve my above 
> described problem?
> 
> 
> -Thanks
> 
> 
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
> 
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