Teach the unroller(s) how to handle an invalid cost. This avoids crashes when the backend can't provide a cost due to either a fundemental limitation or an unimplemented cost model case.
Differential Revision: https://reviews.llvm.org/D127305
This patch adds basic support for `omp task` to the OpenMPIRBuilder.
The outlined function after code extraction is called from a wrapper function with appropriate arguments. This wrapper function is passed to the runtime calls for task allocation.
This approach is different from the Clang approach - clang directly emits the runtime call to the outlined function. The outlining utility (OutlineInfo) simply outlines the code and generates a function call to the outlined function. After the function has been generated by the outlining utility, there is no easy way to alter the function arguments without meddling with the outlining itself. Hence the wrapper function approach is taken.
Reviewed By: Meinersbur
Differential Revision: https://reviews.llvm.org/D71989
This patch moves the logic for generating the offloading entries to the
OpenMPIRBuilder. This makes it easier to re-use in other places, such as
for OpenMP support in Flang or using the same method for generating
offloading entires for other languages like Cuda.
Reviewed By: tianshilei1992
Differential Revision: https://reviews.llvm.org/D123460
The callback is expected to create a branch to the ContinuationBB (sometimes called FiniBB in some lambdas) argument when finishing. This creates problems:
1. The InsertPoint used for CodeGenIP does not need to be the end of a block. If it is not, a naive callback will insert a branch instruction into the middle of the block.
2. The BasicBlock the CodeGenIP is pointing to may or may not have a terminator. There is an conflict where to branch to if the block already has a terminator.
3. Some API functions work only with block having a terminator. Some workarounds have been used to insert a temporary terminator that is removed again.
4. Some callbacks are sensitive to whether the BasicBlock has a terminator or not. This creates a callback ordering problem where different callback may have different behaviour depending on whether a previous callback created a terminator or not. The problem also exists for FinalizeCallbackTy where some callbacks do create branch to another "continue" block, but unlike BodyGenCallbackTy does not receive the target as argument. This is not addressed in this patch.
With this patch, the callback receives an CodeGenIP into a BasicBlock where to insert instructions. If it has to insert control flow, it can split the block at that position as needed but otherwise no separate ContinuationBB is needed. In particular, a callback can be empty without breaking the emitted IR. If the caller needs the control flow to branch to a specific target, it can insert the branch instruction itself and pass an InsertPoint before the terminator to the callback.
Certain frontends such as Clang may expect the current IRBuilder position to be at the end of a basic block. In this case its callbacks must split the block at CodeGenIP before setting the IRBuilder position such that the instructions after CodeGenIP are moved to another basic block and before returning create a new branch instruction to the split block.
Some utility functions such as `splitBB` are supporting correct splitting of BasicBlocks, independent of whether they have a terminator or not, returning/setting the InsertPoint of an IRBuilder to the end of split predecessor block, and optionally omitting creating a branch to the split successor block to be added later.
Reviewed By: kiranchandramohan
Differential Revision: https://reviews.llvm.org/D118409
This reverts commit af0285122f.
The test "libomp::loop_dispatch.c" on builder
openmp-gcc-x86_64-linux-debian fails from time-to-time.
See #54969. This patch is unrelated.
The OMPScheduleType enum stores the constants from libomp's internal sched_type in kmp.h and are used by several kmp API functions. The enum values have an internal structure, namely each scheduling algorithm (e.g.) exists in four variants: unordered, orderend, normerge unordered, and nomerge ordered.
This patch (basically a followup to D114940) splits the "ordered" and "nomerge" bits into separate flags, as was already done for the "monotonic" and "nonmonotonic", so we can apply bit flags operations on them. It also now contains all possible combinations according to kmp's sched_type. Deriving of the OMPScheduleType enum from clause parameters has been moved form MLIR's OpenMPToLLVMIRTranslation.cpp to OpenMPIRBuilder to make available for clang as well. Since the primary purpose of the flag is the binary interface to libomp, it has been made more private to LLVMFrontend. The primary interface for generating worksharing-loop using OpenMPIRBuilder code becomes `applyWorkshareLoop` which derives the OMPScheduleType automatically and calls the appropriate emitter function.
While this is mostly a NFC refactor, it still applies the following functional changes:
* The logic from OpenMPToLLVMIRTranslation to derive the OMPScheduleType also applies to clang. Most notably, it now applies the nonmonotonic flag for non-static schedules by default.
* In OpenMPToLLVMIRTranslation, the nonmonotonic default flag was previously not applied if the simd modifier was used. I assume this was a bug, since the effect was due to `loop.schedule_modifier()` returning `mlir::omp::ScheduleModifier::none` instead of `llvm::Optional::None`.
* In OpenMPToLLVMIRTranslation, the nonmonotonic default flag was set even if ordered was specified, in breach to what the comment before citing the OpenMP specification says. I assume this was an oversight.
The ordered flag with parameter was not considered in this patch. Changes will need to be made (e.g. adding/modifying function parameters) when support for it is added. The lengthy names of the enum values can be discussed, for the moment this is avoiding reusing previously existing enum value names such as `StaticChunked` to avoid confusion.
Reviewed By: peixin
Differential Revision: https://reviews.llvm.org/D123403
This patch supports ordered clause specified without parameter in
worksharing-loop directive in the OpenMPIRBuilder and lowering MLIR to
LLVM IR.
Reviewed By: Meinersbur
Differential Revision: https://reviews.llvm.org/D114940
This patch adds the nowait parameter to `createSingle` in
OpenMPIRBuilder and handling for IR generation from OpenMP Dialect.
Also added tests for the same.
Reviewed By: ftynse
Differential Revision: https://reviews.llvm.org/D122371
This patch adds translation from `omp.atomic.capture` to LLVM IR. Also
added tests for the same.
Depends on D121546
Reviewed By: ftynse
Differential Revision: https://reviews.llvm.org/D121554
This patch fixes the condition for emitting atomic update using
`atomicrmw` instruction or compare-exchange loop.
Reviewed By: ftynse
Differential Revision: https://reviews.llvm.org/D121546
This patch adds lowering from omp.atomic.update to LLVM IR. Whenever a
special LLVM IR instruction is available for the operation, `atomicrmw`
instruction is emitted, otherwise a compare-exchange loop based update
is emitted.
Depends on D119522
Reviewed By: ftynse, peixin
Differential Revision: https://reviews.llvm.org/D119657
The OpenMPIRBuilder has a bug. Specifically, suppose you have two nested openmp parallel regions (writing with MLIR for ease)
```
omp.parallel {
%a = ...
omp.parallel {
use(%a)
}
}
```
As OpenMP only permits pointer-like inputs, the builder will wrap all of the inputs into a stack allocation, and then pass this
allocation to the inner parallel. For example, we would want to get something like the following:
```
omp.parallel {
%a = ...
%tmp = alloc
store %tmp[] = %a
kmpc_fork(outlined, %tmp)
}
```
However, in practice, this is not what currently occurs in the context of nested parallel regions. Specifically to the OpenMPIRBuilder,
the entirety of the function (at the LLVM level) is currently inlined with blocks marking the corresponding start and end of each
region.
```
entry:
...
parallel1:
%a = ...
...
parallel2:
use(%a)
...
endparallel2:
...
endparallel1:
...
```
When the allocation is inserted, it presently inserted into the parent of the entire function (e.g. entry) rather than the parent
allocation scope to the function being outlined. If we were outlining parallel2, the corresponding alloca location would be parallel1.
This causes a variety of bugs, including https://github.com/llvm/llvm-project/issues/54165 as one example.
This PR allows the stack allocation to be created at the correct allocation block, and thus remedies such issues.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D121061
Add applyStaticChunkedWorkshareLoop method implementing static schedule when chunk-size is specified. Unlike a static schedule without chunk-size (where chunk-size is chosen by the runtime such that each thread receives one chunk), we need two nested loops: one for looping over the iterations of a chunk, and a second for looping over all chunks assigned to the threads.
This patch includes the following related changes:
* Adapt applyWorkshareLoop to triage between the schedule types, now possible since all schedules have been implemented. The default schedule is assumed to be non-chunked static, as without OpenMPIRBuilder.
* Remove the chunk parameter from applyStaticWorkshareLoop, it is ignored by the runtime. Change the value for the value passed to the init function to 0, as without OpenMPIRBuilder.
* Refactor CanonicalLoopInfo::setTripCount and CanonicalLoopInfo::mapIndVar as used by both, applyStaticWorkshareLoop and applyStaticChunkedWorkshareLoop.
* Enable Clang to use the OpenMPIRBuilder in the presence of the schedule clause.
Differential Revision: https://reviews.llvm.org/D114413
This patch fixes `createAtomicUpdate` for lowering with float types.
Test added for the same.
This patch also changes the alloca argument for createAtomicUpdate and
createAtomicCapture from `Instruction*` to `InsertPointTy`. This is in
line with the other functions of the OpenMPIRBuilder class which take
AllocaIP as an `InsertPointTy`.
Reviewed By: Meinersbur
Differential Revision: https://reviews.llvm.org/D118227
This patch removes the type punning in atomic compare operation for
floating point values because the direct comparison doesn't make too much sense
for floating point values.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D119378
With opaque pointers, we can no longer derive this from the pointer
type, so we need to explicitly provide the element type the atomic
operation should work with.
Differential Revision: https://reviews.llvm.org/D118359
Summary:
This patch modifies code generation in OpenMPIRBuilder to pass arguments
to the parallel region outlined function in an aggregate (struct),
besides the global_tid and bound_tid arguments. It depends on the
updated CodeExtractor (see D96854) for support. It mirrors functionality
of Clang codegen (see D102107).
Differential Revision: https://reviews.llvm.org/D110114
Follow-up on D117226 for applyStaticWorkshareLoop and
applyDynamicWorkshareLoop checking for conflicting InertPoints via an
assert. There is no in-tree code that violates this assertion, hence
nothing changes.
When a Builder methods accepts multiple InsertPoints, when both point to
the same position, inserting instructions at one position will "move" the
other after the inserted position since the InsertPoint is pegged to the
instruction following the intended InsertPoint. For instance, when
creating a parallel region at Loc and passing the same position as AllocaIP,
creating instructions at Loc will "move" the AllocIP behind the Loc
position.
To avoid this ambiguity, add an assertion checking this condition and
fix the unittests.
In case of AllocaIP, an alternative solution could be to implicitly
split BasicBlock at InsertPoint, using the first as AllocaIP, the second
for inserting the instructions themselves. However, this solution is
specific to AllocaIP since AllocaIP will always have to be first. Hence,
this is an argument to generally handling ambiguous InsertPoints as API
sage error.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D117226
This patch adds OMPIRBuilder support for the simd directive (without any clause). This will be a first step towards lowering simd directive in LLVM_Flang. The patch uses existing CanonicalLoop infrastructure of IRBuilder to add the support. Also adds necessary code to add llvm.access.group and llvm.loop metadata wherever needed.
Reviewed By: Meinersbur
Differential Revision: https://reviews.llvm.org/D114379
This patch changes the visibility of the `__omp_rtl_debug_kind` variable
to be hidden. These variables are only used by the plugin so they do not
need to be read externally. Previously the default visibility prevented
these variables from being completely eliminated in the module.
Reviewed By: tianshilei1992
Differential Revision: https://reviews.llvm.org/D117320
OpenMP runtime requires depend vec with i64 type and the alignment of
store instruction should be set as 8.
Reviewed By: kiranchandramohan, shraiysh
Differential Revision: https://reviews.llvm.org/D116300
One of the unused ident_t fields now holds the size of the string
(=const char *) field so we have an easier time dealing with those
in the future.
Differential Revision: https://reviews.llvm.org/D113126
This patch adds lowering from omp.sections and omp.section (simple lowering along with the nowait clause) to LLVM IR.
Tests for the same are also added.
Reviewed By: ftynse, kiranchandramohan
Differential Revision: https://reviews.llvm.org/D115030
Make the reduction handling in OpenMPIRBuilder compatible with
opaque pointers by explicitly storing the element type in ReductionInfo,
and also passing it to the atomic reduction callback, as at least
the ones in the test need the type there.
This doesn't make things fully compatible yet, there are other
uses of element types in this class. I also left one
getPointerElementType() call in mlir, because I'm not familiar
with that area.
Differential Revison: https://reviews.llvm.org/D115638
This patch supports the atomic construct (update) following section 2.17.7 of OpenMP 5.0 standard. Also added tests and verifier for the same.
Reviewed By: kiranchandramohan, peixin
Differential Revision: https://reviews.llvm.org/D112982
Update `OpenMPIRBuilder::collapseLoops()` to call `resize()` instead of
`set_size()`. The latter asserts on capacity limits and cannot grow,
which seems likely to be unintentional here (if it is, I think a local
assertion would be good for clarity).
Also update `CodeGenFunction::EmitOMPCollapsedCanonicalLoopNest()` to
use `pop_back_n()` instead of `set_size()`.
Differential Revision: https://reviews.llvm.org/D115378
Do not explicitly store the BasicBlocks for Preheader, Body and After inside CanonicalLoopInfo, but look the up when needed using their position relative to the other loop control blocks. By definition, instructions inside these are not managed by CanonicalLoopInfo (except terminator for Preheader) hence it makes sense to think of them as connections to the CanonicalLoopInfo instead of part of the CanonicalLoopInfo itself.
In particular for Preheader, it makes using SplitBasicBlock easier since inserting control flow at an InsertPoint may otherwise require updating the CanonicalLoopInfo's Preheader because the branch that jumps to the header is moved to another BasicBlock.
Reviewed By: ftynse
Differential Revision: https://reviews.llvm.org/D114368
Fix for the case when there are no instructions in the entry basic block before the call
to `createSections`
Reviewed By: Meinersbur
Differential Revision: https://reviews.llvm.org/D114143
This moves the registry higher in the LLVM library dependency stack.
Every client of the target registry needs to link against MC anyway to
actually use the target, so we might as well move this out of Support.
This allows us to ensure that Support doesn't have includes from MC/*.
Differential Revision: https://reviews.llvm.org/D111454
This patch adds two flags to be supported for the new runtime. The flags
are `-fopenmp-assume-threads-oversubscription` and
-fopenmp-assume-teams-oversubscription`. These add global values that
can be checked by the work sharing runtime functions to make better
judgements about how to distribute work between the threads.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D111348
Fixes 51982. Adds a missing CreatePointerCast and allocates a global in
the correct address space.
Test case derived from https://github.com/ROCm-Developer-Tools/aomp/\
blob/aomp-dev/test/smoke/nest_call_par2/nest_call_par2.c by deleting
parts while checking the assertion failure still occurred.
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D110556
Kazu Hirata