The previous conversion from LLVM to MLIR was translating plain LLVM IR
to LLVM MLIR Dialect, as a preliminary step for further conversion from
LLVM MLIR Dialect to Clift.
This is not how things are expected to work anymore, so the old code is
now dead and can be removed.
We introduce a new LLVM Pass that should detect implicit
casts, by marking the 3rd argument of ModelCast as `true`.
The backend will omit printing a cast expression if the
ModelCast is implicit one.
This pass is dedicated to applying a bunch of peephole optimizations
that are useful for decompilation and haven't been implemented in LLVM
for whatever reason.
At the moment it only runs an optimization that tries to reduce the uses
of incoming values of PHINodes, under very specific condidtions, which
enables emitting less LocalVariables.