GPU kernels generated via typical MLIR mechanisms make the assumption
that all workgroups are of uniform size, and so, as in OpenMP, it is
appropriate to set the "uniform-work-group-size"="true" attribute on
these functions by default. This commit makes that choice.
In the event it is needed, this commit adds
`rocdl.uniform_work_group_size` as an attribute to be set on LLVM
functions that can be used to override the default.
In addition, add proper failure messages to translation
This is a new ODS feature that allows dialects to define a list of
key/value pair representing an attribute type and a name.
This will generate helper classes on the dialect to be able to
manage discardable attributes on operations in a type safe way.
For example the `test` dialect can define:
```
let discardableAttrs = (ins
"mlir::IntegerAttr":$discardable_attr_key,
);
```
And the following will be generated in the TestDialect class:
```
/// Helper to manage the discardable attribute `discardable_attr_key`.
class DiscardableAttrKeyAttrHelper {
::mlir::StringAttr name;
public:
static constexpr ::llvm::StringLiteral getNameStr() {
return "test.discardable_attr_key";
}
constexpr ::mlir::StringAttr getName() {
return name;
}
DiscardableAttrKeyAttrHelper(::mlir::MLIRContext *ctx)
: name(::mlir::StringAttr::get(ctx, getNameStr())) {}
mlir::IntegerAttr getAttr(::mlir::Operation *op) {
return op->getAttrOfType<mlir::IntegerAttr>(name);
}
void setAttr(::mlir::Operation *op, mlir::IntegerAttr val) {
op->setAttr(name, val);
}
bool isAttrPresent(::mlir::Operation *op) {
return op->hasAttrOfType<mlir::IntegerAttr>(name);
}
void removeAttr(::mlir::Operation *op) {
assert(op->hasAttrOfType<mlir::IntegerAttr>(name));
op->removeAttr(name);
}
};
DiscardableAttrKeyAttrHelper getDiscardableAttrKeyAttrHelper() {
return discardableAttrKeyAttrName;
}
```
User code having an instance of the TestDialect can then manipulate this
attribute on operation using:
```
auto helper = testDialect.getDiscardableAttrKeyAttrHelper();
helper.setAttr(op, value);
helper.isAttrPresent(op);
...
```
Extend the `amendOperation` mechanism for translating dialect attributes
attached to operations from another dialect when translating MLIR to
LLVM IR. Previously, this mechanism would have no knowledge of the LLVM
IR instructions created for the given operation, making it impossible
for it to perform local modifications such as attaching operation-level
metadata. Collect instructions inserted by the LLVM IR builder and pass
them to `amendOperation`.
The MLIR classes Type/Attribute/Operation/Op/Value support
cast/dyn_cast/isa/dyn_cast_or_null functionality through llvm's doCast
functionality in addition to defining methods with the same name.
This change begins the migration of uses of the method to the
corresponding function call as has been decided as more consistent.
Note that there still exist classes that only define methods directly,
such as AffineExpr, and this does not include work currently to support
a functional cast/isa call.
Caveats include:
- This clang-tidy script probably has more problems.
- This only touches C++ code, so nothing that is being generated.
Context:
- https://mlir.llvm.org/deprecation/ at "Use the free function variants
for dyn_cast/cast/isa/…"
- Original discussion at https://discourse.llvm.org/t/preferred-casting-style-going-forward/68443
Implementation:
This first patch was created with the following steps. The intention is
to only do automated changes at first, so I waste less time if it's
reverted, and so the first mass change is more clear as an example to
other teams that will need to follow similar steps.
Steps are described per line, as comments are removed by git:
0. Retrieve the change from the following to build clang-tidy with an
additional check:
https://github.com/llvm/llvm-project/compare/main...tpopp:llvm-project:tidy-cast-check
1. Build clang-tidy
2. Run clang-tidy over your entire codebase while disabling all checks
and enabling the one relevant one. Run on all header files also.
3. Delete .inc files that were also modified, so the next build rebuilds
them to a pure state.
4. Some changes have been deleted for the following reasons:
- Some files had a variable also named cast
- Some files had not included a header file that defines the cast
functions
- Some files are definitions of the classes that have the casting
methods, so the code still refers to the method instead of the
function without adding a prefix or removing the method declaration
at the same time.
```
ninja -C $BUILD_DIR clang-tidy
run-clang-tidy -clang-tidy-binary=$BUILD_DIR/bin/clang-tidy -checks='-*,misc-cast-functions'\
-header-filter=mlir/ mlir/* -fix
rm -rf $BUILD_DIR/tools/mlir/**/*.inc
git restore mlir/lib/IR mlir/lib/Dialect/DLTI/DLTI.cpp\
mlir/lib/Dialect/Complex/IR/ComplexDialect.cpp\
mlir/lib/**/IR/\
mlir/lib/Dialect/SparseTensor/Transforms/SparseVectorization.cpp\
mlir/lib/Dialect/Vector/Transforms/LowerVectorMultiReduction.cpp\
mlir/test/lib/Dialect/Test/TestTypes.cpp\
mlir/test/lib/Dialect/Transform/TestTransformDialectExtension.cpp\
mlir/test/lib/Dialect/Test/TestAttributes.cpp\
mlir/unittests/TableGen/EnumsGenTest.cpp\
mlir/test/python/lib/PythonTestCAPI.cpp\
mlir/include/mlir/IR/
```
Differential Revision: https://reviews.llvm.org/D150123
1. When converting from the GPU dialect to the ROCDL dialect, if the
function that contains a gpu.thread_id or gpu.block_id op is annotated
with gpu.known_{block,grid}_size, use that size to set a "range"
attribute on the corresponding rocdl intrinsic so that the LLVM
frontend can optimize based on that range information.
1b. When translating from the rocdl dialect to LLVM IR, use the
"range" attribute, if present, to set !range metadata on the relevant
function call.
2. Deprecate the old rocdl.max_flat_work_group_size attribute, which
was used in a tensorflow backend. Instead, use
rocdl.flat_work_group_size going forward to allow kernel generators to
specify the minimum and maximum work group sizes a kernel may be
launched with in one attribute, thus more closely matching the backend.
3. When translating from gpu.func to llvm.func within gpu-to-rocdl,
copy the known_block_size attribute as rocdl.reqd_work_group_size to
enable further translations to set the corresponding metadata on the
LLVM IR function. Also, set the rocdl.flat_work_group_size attribute
to ensure that the reqd_work_group_size metadata and the
amdgpu-flat-work-group-size metadata are consistent.
3b. Extend the ROCDL to LLVM IR translation to set the
!reqd_work_group_size metadata on LLVM functions
Also update tests and add functions to the ROCDL dialect to ensure
attribute names are used consistently.
Depends on D139865
Reviewed By: antiagainst
Differential Revision: https://reviews.llvm.org/D139866
The current dialect registry allows for attaching delayed interfaces, that are added to attrs/dialects/ops/etc.
when the owning dialect gets loaded. This is clunky for quite a few reasons, e.g. each interface type has a
separate tracking structure, and is also quite limiting. This commit refactors this delayed mutation of
dialect constructs into a more general DialectExtension mechanism. This mechanism is essentially a registration
callback that is invoked when a set of dialects have been loaded. This allows for attaching interfaces directly
on the loaded constructs, and also allows for loading new dependent dialects. The latter of which is
extremely useful as it will now enable dependent dialects to only apply in the contexts in which they
are necessary. For example, a dialect dependency can now be conditional on if a user actually needs the
interface that relies on it.
Differential Revision: https://reviews.llvm.org/D120367
While the default value for the amdgpu-flat-work-group-size attribute,
"1, 256", matches the defaults from Clang, some users of the ROCDL dialect,
namely Tensorflow, use larger workgroups, such as 1024. Therefore,
instead of hardcoding this value, we add a rocdl.max_flat_work_group_size
attribute that can be set on GPU kernels to override the default value.
Reviewed By: whchung
Differential Revision: https://reviews.llvm.org/D115741
- Define a gpu.printf op, which can be lowered to any GPU printf() support (which is present in CUDA, HIP, and OpenCL). This op only supports constant format strings and scalar arguments
- Define the lowering of gpu.pirntf to a call to printf() (which is what is required for AMD GPUs when using OpenCL) as well as to the hostcall interface present in the AMD Open Compute device library, which is the interface present when kernels are running under HIP.
- Add a "runtime" enum that allows specifying which of the possible runtimes a ROCDL kernel will be executed under or that the runtime is unknown. This enum controls how gpu.printf is lowered
This change does not enable lowering for Nvidia GPUs, but such a lowering should be possible in principle.
And:
[MLIR][AMDGPU] Always set amdgpu-implicitarg-num-bytes=56 on kernels
This is something that Clang always sets on both OpenCL and HIP kernels, and failing to include it causes mysterious crashes with printf() support.
In addition, revert the max-flat-work-group-size to (1, 256) to avoid triggering bugs in the AMDGPU backend.
Reviewed By: mehdi_amini
Differential Revision: https://reviews.llvm.org/D110448
NamedAttribute is currently represented as an std::pair, but this
creates an extremely clunky .first/.second API. This commit
converts it to a class, with better accessors (getName/getValue)
and also opens the door for more convenient API in the future.
Differential Revision: https://reviews.llvm.org/D113956
There is no need for the interface implementations to be exposed, opaque
registration functions are sufficient for all users, similarly to passes.
Reviewed By: mehdi_amini
Differential Revision: https://reviews.llvm.org/D97852
Port the translation of five dialects that define LLVM IR intrinsics
(LLVMAVX512, LLVMArmNeon, LLVMArmSVE, NVVM, ROCDL) to the new dialect
interface-based mechanism. This allows us to remove individual translations
that were created for each of these dialects and just use one common
MLIR-to-LLVM-IR translation that potentially supports all dialects instead,
based on what is registered and including any combination of translatable
dialects. This removal was one of the main goals of the refactoring.
To support the addition of GPU-related metadata, the translation interface is
extended with the `amendOperation` function that allows the interface
implementation to post-process any translated operation with dialect attributes
from the dialect for which the interface is implemented regardless of the
operation's dialect. This is currently applied to "kernel" functions, but can
be used to construct other metadata in dialect-specific ways without
necessarily affecting operations.
Depends On D96591, D96504
Reviewed By: nicolasvasilache
Differential Revision: https://reviews.llvm.org/D96592
