This patch is one in a series of four patches that 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.
For example, the below case where two members of a Fortran
derived type are mapped explicitly:
''''
type :: scalar_and_array
real(4) :: real
integer(4) :: array(10)
integer(4) :: int
end type scalar_and_array
type(scalar_and_array) :: scalar_arr
!$omp target map(tofrom: scalar_arr%int, scalar_arr%real)
''''
Current cases of derived type mapping left for future work are:
> explicit member mapping of nested members (e.g. two layers of
record types where we explicitly map a member from the internal
record type)
> Fortran's automagical mapping of all elements and nested elements
of a derived type
> explicit member mapping of a derived type and then constituient members
(redundant in Fortran due to former case but still legal as far as I am aware)
> explicit member mapping of a record type (may be handled reasonably, just
not fully tested in this iteration)
> explicit member mapping for Fortran allocatable types (a variation of nested
record types)
This patch seeks to support this by extending the Flang-new OpenMP lowering to
support generation of this newly required information, creating the neccessary
parent <-to-> member map_info links, calculating the member indices and
setting if it's a partial map.
The OMPDescriptorMapInfoGen pass has also been generalized into a map
finalization phase, now named OMPMapInfoFinalization. This pass was extended
to support the insertion of member maps into the BlockArg and MapOperands of
relevant map carrying operations. Similar to the method in which descriptor types
are expanded and constituient members inserted.
Pull Request: https://github.com/llvm/llvm-project/pull/82853
The lowering produces fir.dummy_scope operation if the current
function has dummy arguments. Each hlfir.declare generated
for a dummy argument is then using the result of fir.dummy_scope
as its dummy_scope operand. This is only done for HLFIR.
I was not able to find a reliable way to identify dummy symbols
in `genDeclareSymbol`, so I added a set of registered dummy symbols
that is alive during the variables instantiation for the current
function. The set is initialized during the mapping of the dummy
argument symbols to their MLIR values. It is reset right after
all variables are instantiated - this is done to avoid generating
hlfir.declare operations with dummy_scope for the clones of
the dummy symbols (e.g. this happens with OpenMP privatization).
If this can be done in a cleaner way, please advise.
This patch seeks to add an initial lowering for pointers and allocatable variables
captured by implicit and explicit map in Flang OpenMP for Target operations that
take map clauses e.g. Target, Target Update. Target Exit/Enter etc.
Currently this is done by treating the type that lowers to a descriptor
(allocatable/pointer/assumed shape) as a map of a record type (e.g. a structure) as that's
effectively what descriptor types lower to in LLVM-IR and what they're represented as
in the Fortran runtime (written in C/C++). The descriptor effectively lowers to a structure
containing scalar and array elements that represent various aspects of the underlying
data being mapped (lower bound, upper bound, extent being the main ones of interest
in most cases) and a pointer to the allocated data. In this current iteration of the mapping
we map the structure in it's entirety and then attach the underlying data pointer and map
the data to the device, this allows most of the required data to be resident on the device
for use. Currently we do not support the addendum (another block of pointer data), but
it shouldn't be too difficult to extend this to support it.
The MapInfoOp generation for descriptor types is primarily handled in an optimization
pass, where it expands BoxType (descriptor types) map captures into two maps, one for
the structure (scalar elements) and the other for the pointer data (base address) and
links them in a Parent <-> Child relationship. The later lowering processes will then treat
them as a conjoined structure with a pointer member map.
