[mlir][Vector] Add vector.shuffle tree transformation

mlir/include/mlir/Dialect/Vector/Transforms/LoweringPatterns.h

@@ -297,6 +297,13 @@ void populateVectorBitCastLoweringPatterns(RewritePatternSet &patterns,
 /// n > 1.
 void populateVectorRankReducingFMAPattern(RewritePatternSet &patterns);
 
+/// Populate patterns to rewrite sequences of `vector.to_elements` +
+/// `vector.from_elements` operations into a tree of `vector.shuffle`
+/// operations.
+void populateVectorToFromElementsToShuffleTreePatterns(
+    RewritePatternSet &patterns, PatternBenefit benefit = 1);
+
 } // namespace vector
 } // namespace mlir
+
 #endif // MLIR_DIALECT_VECTOR_TRANSFORMS_LOWERINGPATTERNS_H

mlir/include/mlir/Dialect/Vector/Transforms/Passes.h

@@ -9,6 +9,7 @@
 #ifndef MLIR_DIALECT_VECTOR_TRANSFORMS_PASSES_H_
 #define MLIR_DIALECT_VECTOR_TRANSFORMS_PASSES_H_
 
+#include "mlir/Dialect/Func/IR/FuncOps.h"
 #include "mlir/Dialect/Vector/Transforms/VectorTransforms.h"
 #include "mlir/Pass/Pass.h"
 

mlir/include/mlir/Dialect/Vector/Transforms/Passes.td

@@ -34,4 +34,9 @@ def LowerVectorMultiReduction : Pass<"lower-vector-multi-reduction", "func::Func
   ];
 }
 
+def LowerVectorToFromElementsToShuffleTree
+  : Pass<"lower-vector-to-from-elements-to-shuffle-tree", "func::FuncOp"> {
+  let summary = "Lower `vector.to_elements` and `vector.from_elements` to a tree of `vector.shuffle` operations";
+}
+
 #endif // MLIR_DIALECT_VECTOR_TRANSFORMS_PASSES

mlir/lib/Dialect/Vector/Transforms/CMakeLists.txt

@@ -10,6 +10,7 @@ add_mlir_dialect_library(MLIRVectorTransforms
   LowerVectorScan.cpp
   LowerVectorShapeCast.cpp
   LowerVectorStep.cpp
+  LowerVectorToFromElementsToShuffleTree.cpp
   LowerVectorTransfer.cpp
   LowerVectorTranspose.cpp
   SubsetOpInterfaceImpl.cpp