Integration with mlir and llvm

[AlexandreEichenberger]

We should increase our doc to get info on how to use ONNX-MLIR and then going to MLIR or LLVM

There are a couple of users that asked these questions and that we have resolved:

#1530

after i run the end to end experiment of onnx-mlir , by --EmitLLVMIR - Lower the input to LLVM IR (LLVM MLIR dialect). i get llvm ir dialect, how can i convert it to llvm ir? i try use ./mlir-translate --mlir-to-llvmir,but it does not work! so, peaese tell me how to do?

If you compile with this option --preserveLLVMIR instead, you will get a file with extension .ll that is LLVM IR (outside of MLIR).

#506

same or different problem?