[llvm-branch-commits] [OpenMP][MLIR] Extend explicit derived type member mapping support for OpenMP dialects lowering to LLVM-IR (PR #81510)

[via llvm-branch-commits]

https://github.com/agozillon created https://github.com/llvm/llvm-project/pull/81510

This patch seeks to refactor slightly and extend the current record type map
support that was put in place for Fortran's descriptor types to handle explicit
member mapping for record types at a single level of depth (the case of explicit
mapping of nested record types is currently unsupported).

This patch seeks to support this by extending the OpenMPToLLVMIRTranslation phase
to more generally support record types, building on the prior groundwork in the
Fortran allocatables/pointers patch. It now supports different kinds of record type
mapping, in this case full record type mapping and then explicit member mapping
in which there is a special case for certain types when mapped individually to not
require any parent map link in the kernel argument structure. To facilitate this
required:
   *  The movement of the setting of the map flag type "ptr_and_obj" to respective
         frontends, now supporting it as a possible flag that can be read and printed
         in mlir form. Some minor changes to declare target map type setting was
         neccesary for this.
   * The addition of a member index array operand, which tracks the position
       of the member in the parent, required for caclulating the appropriate size
       to offload to the target, alongside the parents offload pointer (always the
       first member currently being mapped).
   * A partial mapping attribute operand, to indicate if the entire record type is
       being mapped or just member components, aiding the ability to lower
       record types in the different manners that are possible.
   * Refactoring bounds calculation for record types and general arrays to one
       location (as well as load/store generation prior to assigning to the kernel
       argument structure), as a side affect enter/exit/update/data mapping
       should now be more correct and fully support bounds mapping, previously
       this would have only worked for target.