[flang] [llvm] [mlir] [flang][OpenMP] Enable tiling (PR #143715)

[Jan Leyonberg via llvm-commits]

jsjodin wrote:

> I'm not sure the semantic and op verification checks are always right. See llvm-test-suite/Fortran/gfortran/regression/gomp/tile-inner-loops-*.f90. Especially tile-inner-loops-2.f90 where an mlir op verification error gets past semantics.

Thanks for spotting this error, I will take a look. This is an issue in general, since there may be restrictions because of the implementations of some loop transformations that will cause codegen to fail, but should otherwise be legal. The front-end will probably have to capture these limitations and give some error message. This is also a part of the question how to handle checking if combinations of loop transformations are legal. 

https://github.com/llvm/llvm-project/pull/143715