This patch updates the `omp.parallel` operation according to the results
of the discussion in [this
RFC](https://discourse.llvm.org/t/rfc-disambiguation-between-loop-and-block-associated-omp-parallelop/79972).
It is removed from the set of loop wrapper operations, changing the
expected MLIR representation for composite `distribute parallel do/for`
into the following:
```mlir
omp.parallel {
...
omp.distribute {
omp.wsloop {
omp.loop_nest ... { ... }
omp.terminator
}
omp.terminator
}
...
omp.terminator
}
```
MLIR verifiers for operations impacted by this representation change are
updated, as well as related tests. The `LoopWrapperInterface` is also
updated, since it's no longer representing an optional "role" of an
operation but a mandatory set of restrictions instead.
This region is intended to separate alloca operations from reduction
variable initialization. This makes it easier to hoist allocas to the
entry block before control flow and complex code for initialization.
The verifier checks that there is at most one block in the alloc region.
This is not sufficient to avoid control flow in general MLIR, but by the
time we are converting to LLVMIR structured control flow should already
have been lowered to the cf dialect.
1/3
Part 2: https://github.com/llvm/llvm-project/pull/102524
Part 3: https://github.com/llvm/llvm-project/pull/102525
This patch sets the omp.composite unit attr for composite wrapper ops
and also add appropriate checks to the verifiers of supported ops for
the presence/absence of the attribute.
This is patch 2/2 in a series of patches. Patch 1 - #102340.
This patch sorts the clause lists for the following OpenMP operations:
- omp.taskloop
- omp.taskgroup
- omp.target_data
- omp.target_enter_data
- omp.target_exit_data
- omp.target_update
- omp.target
This change results in the reordering of operation arguments, so
impacted unit tests are updated accordingly.
This patch sorts the clause lists for the following OpenMP operations:
- omp.parallel
- omp.teams
- omp.sections
- omp.wsloop
- omp.distribute
- omp.task
This change results in the reordering of operation arguments, so
impacted unit tests are updated accordingly.
This patch adds the missing `OpenMP_Clause` definitions to all existing
`OpenMP_Op`s and updates their operand structure based builders to
initialize the new arguments.
The result of this change is that operation operand structures are now
based in the same list of clauses as their tablegen counterparts. This
means that all of the information needed is now in place to
automatically generate OpenMP operand structures from tablegen
defitions.
Since this change doesn't involve the introduction of actual support for
these clauses, new arguments are not initialized from values stored in
the corresponding operand structure fields but rather set to empty or
null. Those should be updated when support for these clauses on the
corresponding operation is added.
This patch introduces a new OpenMP clause definition not defined by the spec.
Its main purpose is to define the `loop_inclusive` (previously "inclusive",
renamed according to the parent of this PR in the stack) argument of
`omp.loop_nest` in such a way that a followup implementation of a tablegen
backend to automatically generate clause and operation operand structures
directly from `OpenMP_Op` and `OpenMP_Clause` definitions can properly generate
the `LoopNestOperands` structure.
`collapse` clause arguments are also moved into this new definition, as they
represent information on the loop nests being collapsed rather than the
`collapse` clause itself.
Currently, there are some inconsistencies to how clause arguments are
named in the OpenMP dialect. Additionally, the clause operand structures
associated to them also diverge in certain cases. The purpose of this
patch is to normalize argument names across all `OpenMP_Clause` tablegen
definitions and clause operand structures.
This has the benefit of providing more consistent representations for
clauses in the dialect, but the main short-term advantage is that it
enables the development of an OpenMP-specific tablegen backend to
automatically generate the clause operand structures without breaking
dependent code.
The main re-naming decisions made in this patch are the following:
- Variadic arguments (i.e. multiple values) have the "_vars" suffix.
This and other similar suffixes are removed from array attribute
arguments.
- Individual required or optional value arguments do not have any suffix
added to them (e.g. "val", "var", "expr", ...), except for `if` which
would otherwise result in an invalid C++ variable name.
- The associated clause's name is prepended to argument names that don't
already contain it as part of its name. This avoids future collisions
between arguments named the same way on different clauses and adding
both clauses to the same operation.
- Privatization and reduction related arguments that contain lists of
symbols pointing to privatizer/reducer operations use the "_syms"
suffix. This removes the inconsistencies between the names for
"copyprivate_funcs", "[in]reductions", "privatizers", etc.
- General improvements to names, replacement of camel case for snake
case everywhere, etc.
- Renaming of operation-associated operand structures to use the
"Operands" suffix in place of "ClauseOps", to better differentiate
between clause operand structures and operation operand structures.
- Fields on clause operand structures are sorted according to the
tablegen definition of the same clause.
The assembly format for a few arguments is updated to better reflect the
clause they are associated with:
- `chunk_size` -> `dist_schedule_chunk_size`
- `grain_size` -> `grainsize`
- `simd` -> `par_level_simd`
The `OpenMPDialectFoldInterface` was originally introduced to prevent
constants from being hoisted out of `omp.target` regions. This hasn't
been necessary since the `IsolatedFromAbove` trait was added to that
operation, so it's safe to remove this interface.
Adding MLIR Op support for omp masked. Omp masked is introduced in 5.2
standard and allows a region to be executed by threads
specified by a programmer. This is achieved with the help of filter
clause which helps to specify thread id expected to execute the region.
This patch updates `OpenMP_Op` definitions to be based on the new set of
`OpenMP_Clause` definitions, and to take advantage of clause-based
automatically-generated argument lists, descriptions, assembly format
and class declarations.
There are also changes introduced to the clause operands structures to
match the current set of tablegen clause definitions. These two are very
closely linked and should be kept in sync. It would probably be a good
idea to try generating clause operands structures from the tablegen
`OpenMP_Clause` definitions in the future.
As a result of this change, arguments for some operations have been
reordered. This patch also addresses this by updating affected operation
build calls and unit tests. Some other updates to tests related to the
order of arguments in the resulting assembly format and others due to
certain previous inconsistencies in the printing/parsing of clauses are
addressed.
The printer and parser functions for the `map` clause are updated, so
that they are able to handle `map` clauses linked to entry block
arguments as well as those which aren't.
This PR causes a build failure in the flang subproject. This is addressed
by the next PR in the stack.
Now all operations with a reduction clause have an array of bools
controlling whether each reduction variable should be passed by
reference or value.
This was already supported for Wsloop and Parallel. The new operations
modified here currently have no flang lowering or translation to LLVMIR
and so further changes are not needed.
It isn't possible to check the verifier in
mlir/test/Dialect/OpenMP/invalid.mlir because there is no way of parsing
an operation to have an incorrect number of byref attributes. The
verifier exists to pick up buggy operation builders or in-place
operation modification.
Fixes#88935
Toggling reduction by-ref broke when multiple reduction clauses were
used. Decisions made for the by-ref status for later clauses could then
invalidate decisions for earlier clauses. For example,
```
reduction(+:scalar,scalar2) reduction(+:array)
```
The first clause would choose by value reduction and generate by-value
reduction regions, but then after this the second clause would force
by-ref to support the array argument. But by the time the second clause
is processed, the first clause has already had the wrong kind of
reduction regions generated.
This is solved by toggling whether a variable should be reduced by
reference per variable. In the above example, this allows only `array`
to be reduced by ref.
This PR adds two new fields to omp.map_info, one BoolAttr and one I64ArrayAttr.
The BoolAttr is named partial_map, and is a flag that indicates if the record type captured by
the map_info operation is a partial map, or if it is mapped in its entirety, this currently helps
the later lowering determine the type of map entries that need to be generated.
The I64ArrayAttr named members_index is intended to track the placement of each member
map_info operations (and by extension mapped member variable) placement in the parent
record type. This may need to be extended to an N-D array for nested member mapping.
Pull Request: https://github.com/llvm/llvm-project/pull/82851
Extends `omp.private` with a new region: `dealloc` where deallocation
logic for Fortran deallocatables will be outlined (this will happen in
later PRs).
This patch updates verifiers for `omp.ordered`, `omp.ordered.region`,
`omp.cancel` and `omp.cancellation_point`, which check for a parent
`omp.wsloop`.
After transitioning to a loop wrapper-based approach, the expected
direct parent will become `omp.loop_nest` instead, so verifiers need to
take this into account.
This PR on its own will not pass premerge tests. All patches in the
stack are needed before it can be compiled and passes tests.
This patch updates the definition of `omp.wsloop` to enforce the
restrictions of a loop wrapper operation.
Related tests are updated but this PR on its own will not pass premerge
tests. All patches in the stack are needed before it can be compiled and
passes tests.
This patch extends verification of the `omp.parallel` operation to check
it is correctly defined when taking a loop wrapper role.
In OpenMP, a PARALLEL construct can be either a (potenially combined)
block construct or a loop construct, when appearing as part of a
composite construct. This is currently the case for the DISTRIBUTE
PARALLEL DO/FOR and DISTRIBUTE PARALLEL DO/FOR SIMD exclusively.
When used to represent the PARALLEL leaf of a composite construct, it
must follow the rules of a wrapper loop operation in MLIR, and this is
what this patch ensures. No additional restrictions are introduced for
PARALLEL block constructs.
This patch removes the LoopControl parsing/printing functions that are
no longer used after transitioning `omp.simdloop` and `omp.taskloop`
into loop wrapper operations.
This patch updates the definition of `omp.simdloop` to enforce the
restrictions of a wrapper operation. It has been renamed to `omp.simd`,
to better reflect the naming used in the spec. All uses of "simdloop" in
function names have been updated accordingly.
Some changes to Flang lowering and OpenMP to LLVM IR translation are
introduced to prevent the introduction of compilation/test failures. The
eventual long term solution might be different.
This patch defines a common interface to be shared by all OpenMP loop
wrapper operations. The main restrictions these operations must meet in
order to be considered a wrapper are:
- They contain a single region.
- Their region contains a single block.
- Their block only contains another loop wrapper or `omp.loop_nest` and
a terminator.
The new interface is attached to the `omp.parallel`, `omp.wsloop`,
`omp.simdloop`, `omp.distribute` and `omp.taskloop` operations. It is
not currently enforced that these operations meet the wrapper
restrictions, which would break existing OpenMP loop-generating code.
Rather, this will be introduced progressively in subsequent patches.
This patch updates Flang lowering to use the new set of OpenMP clause
operand structures and their groupings into directive-specific sets of
clause operands.
It simplifies the passing of information from the clause processor and
the creation of operations.
The `DataSharingProcessor` is slightly modified to not hold delayed
privatization state. Instead, optional arguments are added to
`processStep1` which are only passed when delayed privatization is used.
This enables using the clause operand structure for `private` and
removes the need for the ad-hoc `DelayedPrivatizationInfo` structure.
The processing of the `schedule` clause is updated to process the
`chunk` modifier rather than requiring two separate calls to the
`ClauseProcessor`.
Lowering of a block-associated `ordered` construct is updated to emit a
TODO error if the `simd` clause is specified, since it is not currently
supported by the `ClauseProcessor` or later compilation stages.
Removed processing of `schedule` from `omp.simdloop`, as it doesn't
apply to `simd` constructs.
This patch introduces an operation intended to hold loop information
associated to the `omp.distribute`, `omp.simdloop`, `omp.taskloop` and
`omp.wsloop` operations. This is a stopgap solution to unblock work on
transitioning these operations to becoming wrappers, as discussed in
[this
RFC](https://discourse.llvm.org/t/rfc-representing-combined-composite-constructs-in-the-openmp-dialect/76986).
Long-term, this operation will likely be replaced by
`omp.canonical_loop`, which is being designed to address missing support
for loop transformations, etc.
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
Fixed build error caused by Squash merge which needs rebase
This patch introduces a set of composable structures grouping the MLIR
operands associated to each OpenMP clause. This makes it easier to keep
the MLIR representation for the same clause consistent throughout all
operations that accept it.
The relevant clause operand structures are grouped into per-operation
structures using a mixin pattern and used to define new operation
constructors. These constructors can be used to avoid having to get the
order of a possibly large list of operands right.
Missing clauses are documented as TODOs, as well as operands which are
part of the relevant operation's operand structure but cannot be
attached to the associated operation yet, due to missing op arguments to
its MLIR definition.
A follow-up patch will update Flang lowering to make use of these
structures, simplifying the passing of information from clause
processing to operation-generating functions and also simplifying the
creation of operations through the use of the new operation
constructors.
Currently, by-ref reductions will allocate the per-thread reduction
variable in the initialization region. Adding a cleanup region allows
that allocation to be undone. This will allow flang to support reduction
of arrays stored on the heap.
This conflation of allocation and initialization in the initialization
should be fixed in the future to better match the OpenMP standard, but
that is beyond the scope of this patch.
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>
Adds basic support for materializing delayed privatization. So far, the
restrictions on the implementation are:
- Only `private` clauses are supported (`firstprivate` support will be
added in a later PR).
Extends the `omp.parallel` op by adding a `private` clause to model
[first]private variables. This uses the `omp.private` op to map
privatized variables to their corresponding privatizers.
Example `omp.private` op with `private` variable:
```
omp.parallel private(@x.privatizer %arg0 -> %arg1 : !llvm.ptr) {
^bb0(%arg1: !llvm.ptr):
// ... use %arg1 ...
omp.terminator
}
```
Whether the variable is private or firstprivate is determined by the
attributes of the corresponding `omp.private` op.
Introduces conversion of `omp.private`'s regions to the LLVM dialect.
This reuses the already existing conversion pattern for
`ReducetionDeclareOp` and repurposes it to be used for multi-region ops
as well.
This adds a new custom CopyPrivateVarList to the single operation.
Each list item is formed by a reference to the variable to be
updated, its type and the function to be used to perform the copy.
It will be translated to LLVM IR using OpenMP builder, that will
use the information in the copyprivate list to call
__kmpc_copyprivate.
This is patch 2 of 4, to add support for COPYPRIVATE in Flang.
Original PR: https://github.com/llvm/llvm-project/pull/73128
This patch reworks the way that wsloop reduction operations function to
better match the expected semantics from the OpenMP specification,
following the rework of parallel reductions.
The new semantics create a private reduction variable as a block
argument which should be used normally for all operations on that
variable in the region; this private variable is then combined with the
others into the shared variable. This way no special omp.reduction
operations are needed inside the region. These block arguments follow
the loop control block arguments.
---------
Co-authored-by: Kiran Chandramohan <kiran.chandramohan@arm.com>
This patch adds support for the depend clause in a number of OpenMP
directives/constructs related to offloading. Specifically, it adds the
handling of the depend clause when it is used with the following
constructs
- target
- target enter data
- target update data
- target exit data
This PR adds a new op to the OpenMP dialect: `PrivateClauseOp`. This op
will be later used to model `[first]private` clauses for differnt OpenMP
directives.
This is part of productizing the "delayed privatization" PoC which can
be found in #79862.
This patch reworks the way that parallel reduction operations function
to better match the expected semantics from the OpenMP specification.
Previously specific omp.reduction operations were used inside the
region, meaning that the reduction only applied when the correct
operation was used, whereas the specification states that any change to
the variable inside the region should be taken into account for the
reduction.
The new semantics create a private reduction variable as a block
argument which should be used normally for all operations on that
variable in the region; this private variable is then combined with the
others into the shared variable. This way no special omp.reduction
operations are needed inside the region.
This patch only makes the change for the `parallel` operation, the
change for the `wsloop` operation will be in a separate patch.
---------
Co-authored-by: Kiran Chandramohan <kiran.chandramohan@arm.com>
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.
This patch adds the omp.distribute operation to the OMP dialect. The
purpose is to be able to represent the distribute construct in OpenMP
with the associated clauses. The effect of the operation is to
distributes the loop iterations of the loop(s) contained inside the
region across multiple teams.
After the removal of the OpenMP early outlining MLIR pass in #67319, the
`EarlyOutliningInterface` stopped doing any useful work. It used to be
necessary to tie the name of the function from which a target region was
outlined to that new function, so it would be used when translating to
LLVM IR in place of the outlined function's name.
This is not necessary anymore, so this patch removes all references to
this interface and uses of the `omp.outline_parent_name` discardable
attribute in tests.
Add an op in the OMP dialect to model the `target update` direcive. This
change reuses the `MapInfoOp` used by other device directive to model
`map` clauses but verifies that the restrictions imposed by the `target
update` directive are respected.
