Reverting a workaround intended specifically for SPRI-V. That workaround
emerged from this discussion:
* https://github.com/llvm/llvm-project/pull/72105
AFAIK, it hasn't been required in practice. This is based on IREE
(https://github.com/openxla/iree), which has just bumped it's fork of
LLVM without using it (*).
(*) cef31e775e
This reverts commit bbd2b08b95fe76bea138c1b03c1cd42ed3ee04df.
Following the discussion here:
* https://github.com/llvm/llvm-project/pull/72105
this patch makes the `TransposeOpLowering` configurable so that one can select
whether to favour `vector.shape_cast` over `vector.transpose`.
As per the discussion in #72105, using `vector.shape_cast` is very beneficial
and desirable when targeting `LLVM IR` (CPU lowering), but won't work when
targeting `SPIR-V` today (GPU lowering). Hence the need for a mechanism to be
able to disable/enable the pattern introduced in #72105. This patch proposes one
such mechanism.
While this should solve the problem that we are facing today, it's understood to
be a temporary workaround. It should be removed once support for lowering
`vector.shape_cast` to SPIR-V is added. Also, (once implemented) the following
proposal might make this workaround redundant:
* https://discourse.llvm.org/t/improving-handling-of-unit-dimensions-in-the-vector-dialect/
* Declare arguments/results with `let` statements.
* Rename `transp` to `permutation`.
* Change type of `transp` from `I64ArrayAttr` to `DenseI64ArrayAttr`
(provides direct access to `ArrayRef<int64_t>` instead of `ArrayAttr`).
This patch extends the vector.transpose lowering to replace:
vector.transpose %0, [1, 0] : vector<nx1x<eltty>> to vector<1xnx<eltty>>
with:
vector.shape_cast %0 : vector<nx1x<eltty>> to vector<1xnx<eltty>>
Source with leading unit-dim (inverse) is also replaced. Unit dim must
be fixed. Non-unit dim can be scalable.
A check is also added to bail out for scalable vectors before unrolling.
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
The existing vector.transpose lowering patterns only triggers if the
input vector is 2D. The revision extends the pattern to handle n-D
vectors which are effectively 2-D vectors (e.g., vector<1x4x1x8x1).
It refactors a common check about 2-D vectors from X86Vector
lowering to VectorUtils.h so it can be reused by both sides.
Reviewed By: dcaballe
Differential Revision: https://reviews.llvm.org/D149908
Vector dialect patterns have grown enormously in the past year to a point where they are now impenetrable.
Start reorganizing them towards finer-grained control.
Differential Revision: https://reviews.llvm.org/D146736
