Reference: https://www.jeremykun.com/2023/08/10/mlir-running-and-testing-a-lowering/

Note: Check Setup the Environment of MLIR for the environment setup.

1. Implementing a Lowering

Create a file “ctlz.mlir”:

func.func @main(%arg0: i32) -> i32 {
  %0 = math.ctlz %arg0 : i32
  func.return %0 : i32
}

Lower the math.ctlz operation to the llvm.ctlz operation with mlir-opt:

mlir-opt --convert-math-to-funcs=convert-ctlz ./ctlz.mlir