This PR proposes re-modelling `reduce` specifiers to match OpenMP and
OpenACC. In particular, this PR includes the following:
* A new `fir` op: `fir.delcare_reduction` which is identical to OpenMP's
`omp.declare_reduction` op.
* Updating the `reduce` clause on `fir.do_concurrent.loop` to use the
new op.
* Re-uses the `ReductionProcessor` component to emit reductions for `do
concurrent` just like we do for OpenMP. To do this, the
`ReductionProcessor` had to be refactored to be more generalized.
* Upates mapping `do concurrent` to `fir.loop ... unordered` nests using
the new reduction model.
Unfortunately, this is a big PR that would be difficult to divide up in
smaller parts because the bottom of the changes are the `fir` table-gen
changes to `do concurrent`. However, doing these MLIR changes cascades
to the other parts that have to be modified to not break things.
This PR goes in the same direction we went for `private/local`
speicifiers. Now the `do concurrent` and OpenMP (and OpenACC) dialects
are modelled in essentially the same way which makes mapping between
them more trivial, hopefully.
PR stack:
- https://github.com/llvm/llvm-project/pull/145837 (this one)
- https://github.com/llvm/llvm-project/pull/146025
- https://github.com/llvm/llvm-project/pull/146028
- https://github.com/llvm/llvm-project/pull/146033
Extending `fir.do_concurrent` to `fir.do_loop ... unordered` lowering by
adding support for lowring/inlining non-empty `init` and `dealloc`
regions.
Resolves https://github.com/llvm/llvm-project/issues/143897 (actually
handles the todo).
This is similar to other configuration objects used across MLIR.
Rename some fields to better reflect that they are no longer booleans.
Reland 04d261101b4f229189463136a794e3e362a793af / #132253.
