Added lowering support for IS_DEVICE_PTR and HAS_DEVICE_ADDR clauses for
OMP TARGET directive and added related tests for these changes.
IS_DEVICE_PTR and HAS_DEVICE_ADDR clauses apply to OMP TARGET directive
OpenMP spec states
`The **is_device_ptr** clause indicates that its list items are device
pointers.`
`The **has_device_addr** clause indicates that its list items already
have device addresses and therefore they may be directly accessed from a
target device.`
Whereas USE_DEVICE_PTR and USE_DEVICE_ADDR clauses apply to OMP TARGET
DATA directive and OpenMP spec for them states
`Each list item in the **use_device_ptr** clause results in a new list
item that is a device pointer that refers to a device address`
`Each list item in a **use_device_addr** clause that is present in the
device data environment is treated as if it is implicitly mapped by a
map clause on the construct with a map-type of alloc`
This adds support for complex type to the OpenMP reductions.
Note that some more work would be needed to give decent error messages when complex
is used in ways that need client supplied functions (e.g. MAX or MIN). It does fail these with
a not so user friendly message at present.
There were several functions, mostly reduction-related, that were only
called from OpenMP.cpp. Remove them from OpenMP.h, and make them local
in OpenMP.cpp:
- genOpenMPReduction
- findReductionChain
- getConvertFromReductionOp
- updateReduction
- removeStoreOp
Also, move the function bodies out of the "public" section.
The clause templates defined in ClauseT.h were originally based on
flang's parse tree nodes. Since those representations are going to be
reused for clang (together with the clause splitting code), it makes
sense to separate them from flang, and instead have them based on the
actual OpenMP spec (v5.2).
The member names in the templates follow the naming presented in the
spec, and the representation (e.g. members) is derived from the clause
definitions as described in the spec.
Since the representations of some clauses has changed (while preserving
the information), the current code using the clauses (especially the
code converting parser::OmpClause to omp::Clause) needs to be adjusted.
This patch does not make any functional changes.
Put all of the genOMP functions together, organize them in two groups:
for declarative constructs and for other (executable) constructs.
Replace visit functions for OpenMPDeclarativeConstruct and
OpenMPConstruct from listing individual visitors for each variant
alternative to using a single generic visitor. Essentially, going from
```
std::visit(
[](foo x) { genOMP(foo); }
[](bar x) { TODO }
[](baz x) { genOMP(baz); }
)
```
to
```
void genOMP(bar x) { // Separate visitor for an unhandled case
TODO
}
[...]
std::visit([&](auto &&s) { genOMP(s); }) // generic
```
This doesn't change any functionality, just reorganizes the functions a
bit. The intent here is to improve the readability of this file.
This patch contains slight modifications to the reverted PR #85258 to
avoid issues with constructs containing multiple reduction clauses,
uncovered by a test on the gfortran testsuite.
This reverts commit 9f80444c2e669237a5c92013f1a42b91b5609012.
The related functions are `gatherDataOperandAddrAndBounds` and
`genBoundsOps`. The former is used in OpenACC as well, and it was
updated to pass evaluate::Expr instead of parser objects.
The difference in the test case comes from unfolded conversions of index
expressions, which are explicitly of type integer(kind=8).
Delete now unused `findRepeatableClause2` and `findClause2`.
Add `AsGenericExpr` that takes std::optional. It already returns
optional Expr. Making it accept an optional Expr as input would reduce
the number of necessary checks when handling frequent optional values in
evaluator.
[Clause representation 4/6]
Re-use fir::getTypeAsString instead of creating something new here. This
spells integer names like i32 instead of i_32 so there is a lot of test
churn.
This has been tested with arrays with compile-time constant bounds.
Allocatable arrays and arrays with non-constant bounds are not yet
supported. User-defined reduction functions are also not yet supported.
The design is intended to work for arrays with non-constant bounds too
without a lot of extra work (mostly there are bugs in OpenMPIRBuilder I
haven't fixed yet).
We need some way to get these runtime bounds into the reduction init and
combiner regions. To keep things simple for now I opted to always box
the array arguments so the box can be passed as one argument and the
lower bounds and extents read from the box. This has the disadvantage of
resulting in fir.box_dim operations inside of the critical section. If
these prove to be a performance issue, we could follow OpenACC reading
box lower bounds and extents before the reduction and passing them as
block arguments to the reduction init and combiner regions. I would
prefer to keep things simple for now.
Note: this implementation only works when the HLFIR lowering is used. I
don't think it is worth supporting FIR-only lowering because the plan is
for that to be removed soon.
OpenMP array reductions 6/6
Previous PR: https://github.com/llvm/llvm-project/pull/84957
This patch moves some code in PFT to MLIR OpenMP lowering to the
`ClauseProcessor` class. This is so that some behavior that is related
to certain clauses stays within the `ClauseProcessor` and it's not the
caller the one responsible for always doing this when the clause is
present.
In this patch some uses of `llvm::SmallVector` in Flang's lowering to
MLIR are replaced by other types (i.e. `llvm::ArrayRef` and
`llvm::SmallVectorImpl`) which are intended for these uses. This
generally prevents relying on always passing small vectors with a
particular number of elements in the stack.
…essor
Rename `findRepeatableClause` to `findRepeatableClause2`, and make the
new `findRepeatableClause` operate on new `omp::Clause` objects.
Leave `Map` unchanged, because it will require more changes for it to
work.
[Clause representation 3/6]
Temporarily rename old clause list to `clauses2`, old clause iterator to
`ClauseIterator2`.
Change `findUniqueClause` to iterate over `omp::Clause` objects, modify
all handlers to operate on 'omp::clause::xyz` equivalents.
[Clause representation 2/6]
In file included from ../llvm-project/flang/lib/Lower/OpenMP/Clauses.cpp:9:
../llvm-project/flang/lib/Lower/OpenMP/Clauses.h:195:17: error: suggest braces around initialization of subobject [-Werror,-Wmissing-braces]
195 | return Clause{id, specific, source};
| ^~~~~~~~~~~~
| { }
The new set of classes representing OpenMP classes mimics the contents
of parser::OmpClause, but differs in a few aspects:
- it can be easily created, copied, etc.
- is based on semantics::SomeExpr instead of parser objects.
This set of classes is geared towards a language-agnostic representation
of OpenMP clauses. While the class members are still based on flang's
`parser::OmpClause`, the classes themselves are actually C++ templates
parameterized with types essential to represent necessary information.
The two parameters are
- `IdType`: the type that can represent object's identity (for flang it
will be `semantics::Symbol *`),
- `ExprType`: the type that can represent expressions, arithmetic and
object references (`semantics::MaybeExpr` in flang).
The templates are defined in a namespace `tomp` (to distinguish it from
`omp`).
This patch introduces file "Clauses.cpp", which contains instantiations
of all of the templates for flang. The instantiations are members of
namespace `omp`, and include an all-encompassing variant class
`omp::Clause`, which is the analog of `parser::OmpClause`.
The class `OmpObject` is represented by `omp::Object`, which contains
the symbol associated with the object, and `semantics::MaybeExpr`
representing the designator for the symbol reference. For each specific
clause in the variant `parser::OmpClause`, there exists a `make`
function that will generate the corresponding `omp::Clause` from it. The
intent was to use the make functions as variant visitors. The creation
of a clause instance would then follow the pattern:
```
omp::Clause clause = std::visit([](auto &&s) { return make(s, semaCtx); }, parserClause.u);
```
If a new clause `foo` is added in the future, then:
- a new template `tomp::FooT` representing the clause needs to be added
to ClauseT.h,
- a new instance needs to be created in flang, this can be as simple as
`using Foo = tomp::FooT<...>`,
- a new make function needs to be implemented to create object of class
Foo from `parser::OmpClause::Foo`.
This patch only introduces the new classes, they are not yet used
anywhere.
[Clause representation 1/6]
This effectively implements some now deprecated OpenMP functionality
that some applications (most notably at the moment GenASiS)
unfortunately depend on (deprecated in specification version 5.2):
"If a list item in a use_device_ptr clause is not of type C_PTR, the
behavior is as if the list item appeared in a use_device_addr clause.
Support for such list items in a use_device_ptr clause is deprecated."
This PR downgrades the hard-error to a deprecated warning and "promotes"
the above cases by simply moving the offending operands from the
use_device_ptr value list to the back of the use_device_addr list (and
moves the related symbols, locs and types that form the BlockArgs
correspondingly) and then the generation of the target data construct
proceeds as normal.
Previously reduction variables were always passed by value into and out
of the initialization and combiner regions of the OpenMP reduction
declare operation.
This worked well for reductions of primitive types (and might perform
better than passing by reference). But passing by reference will be
useful for array and derived type reductions (e.g. to move allocation
inside of the init region).
Passing reductions by reference requires different LLVM-IR generation
when lowering from MLIR because some of the loads/stores/allocations
will now be moved inside of the init and combiner regions. This
alternate code generation is requested using a new attribute to
omp.wsloop and omp.parallel.
Existing lowerings from mlir are unaffected (these will continue to use
the by-value argument passing.
Flang will continue to pass by-value argument passing for trivial types
unless a (hidden) command line argument is supplied. Non-trivial types
will always use the by-ref lowering.
Array reductions are not ready yet (but are coming very soon). In the
meantime, this is tested by forcing existing reductions to use by-ref.
Commit series for by-ref OpenMP reductions 3/3
---------
Co-authored-by: Mats Petersson <mats.petersson@arm.com>
As per the OpenMP standard, "If a variable appears in a link clause on a
declare target directive that does not have a device_type clause with
the nohost device-type-description then it is treated as if it had
appeared in a map clause with a map-type of tofrom" is an implicit
mapping rule. Before this change, such variables were mapped as to by
default.
This patch seeks to create a process that happens on module finalization
for OpenMP, in which a list of operations that had declare target
directives applied to them and were not generated at the time of
processing the original declare target directive are re-checked to apply
the appropriate declare target semantics.
This works by maintaining a vector of declare target related data inside
of the FIR converter, in this case the symbol and the two relevant
unsigned integers representing the enumerators. This vector is added to
via a new function called from Bridge.cpp, insertDeferredDeclareTargets,
which happens prior to the processing of the directive (similarly to
getDeclareTargetFunctionDevice currently for requires), it effectively
checks if the Operation the declare target directive is applied to
currently exists, if it doesn't it appends to the vector. This is a
seperate function to the processing of the declare target via the
overloaded genOMP as we unfortunately do not have access to the list
without passing it through every call, as the AbstractConverter we pass
will not allow access to it (I've seen no other cases of casting it to a
FirConverter, so I opted to not do that).
The list is then processed at the end of the module in the
finalizeOpenMPLowering function in Bridge by calling a new function
markDelayedDeclareTargetFunctions which marks the latently generated
operations. In certain cases, some still will not be generated, e.g. if
an interface is defined, marked as declare target, but has no definition
or usage in the module then it will not be emitted to the module, so due
to these cases we must silently ignore when an operation has not been
found via it's symbol.
The main use-case for this (although, I imagine there is others) is for
processing interfaces that have been declared in a module with a declare
target directive but do not have their implementation defined in the
same module. For example, inside of a seperate C++ module that will be
linked in. In cases where the interface is called inside of a target
region it'll be marked as used on device appropriately (although,
realistically a user should explicitly mark it to match the
corresponding definition), however, in cases where it's used in a
non-clear manner through something like a function pointer passed to an
external call we require this explicit marking, which this patch adds
support for (currently will cause the compiler to crash).
This patch also adds documentation on the declare target process and
mechanisms within the compiler currently.
Add the [[maybe_unused]] attribute to a variable in
lib/Lower/OpenMP/OpenMP.cpp to avoid a (possibly bogus) unused variable
warning when building with GCC 9.3.0.
PR #81833 introduced some changes to broke some debug builds. This
happened due to an indirectly included file referencing an `operator <<`
function which is defined in a `.cpp` file that not linked with `tco`
and `fir-opt`.
Adds basic support for emitting delayed privatizers from flang. So far,
only types of symbols are supported (i.e. scalars), support for more
complicated types will be added later. This also makes sure that
reduction and delayed privatization work properly together by merging
the
body-gen callbacks for both in case both clauses are present on the
parallel construct.
Add initial handling of OpenMP copyprivate clause in Flang.
When lowering copyprivate, Flang generates the copy function
needed by each variable and builds the appropriate
omp.single's CopyPrivateVarList.
This is patch 3 of 4, to add support for COPYPRIVATE in Flang.
Original PR: https://github.com/llvm/llvm-project/pull/73128
This patch adds support in flang for the depend clause in target and
target enter/update/exit constructs. Previously, the following line in a
fortran program would have resulted in the error shown below it.
!$omp target map(to:a) depend(in:a)
"not yet implemented: Unhandled clause DEPEND in TARGET construct"
This started as an experiment to reduce the compilation time of
iterating over `Lower/OpenMP.cpp` a bit since it is too slow at the
moment. Trying to do that, I split the `DataSharingProcessor`,
`ReductionProcessor`, and `ClauseProcessor` into their own files and
extracted some shared code into a util file. All of these new `.h/.cpp`
files as well as `OpenMP.cpp` are now under a `Lower/OpenMP/` directory.
This resulted is a slightly better organization of the OpenMP lowering
code and hence opening this NFC.
As for the compilation time, this unfortunately does not affect it much
(it shaves off a few seconds of `OpenMP.cpp` compilation) since from
what I learned the bottleneck is in `DirectivesCommon.h` and
`PFTBuilder.h` which both consume a lot of time in template
instantiation it seems.
