[mlir][VectorOps] Add vector.interleave operation (#80965)

The interleave operation constructs a new vector by interleaving the
elements from the trailing (or final) dimension of two input vectors,
returning a new vector where the trailing dimension is twice the size.

Note that for the n-D case this differs from the interleaving possible
with `vector.shuffle`, which would only operate on the leading
dimension.

Another key difference is this operation supports scalable vectors,
though currently a general LLVM lowering is limited to the case where
only the trailing dimension is scalable.

Example:
```mlir
%0 = vector.interleave %a, %b
            : vector<[4]xi32>     ; yields vector<[8]xi32>
%1 = vector.interleave %c, %d
            : vector<8xi8>        ; yields vector<16xi8>
%2 = vector.interleave %e, %f
            : vector<f16>         ; yields vector<2xf16>
%3 = vector.interleave %g, %h
            : vector<2x4x[2]xf64> ; yields vector<2x4x[4]xf64>
%4 = vector.interleave %i, %j
            : vector<6x3xf32>     ; yields vector<6x6xf32>
```

Note: This change alone does not add any lowerings.

Author: MacDue

mlir/include/mlir/Dialect/Vector/IR/VectorOps.td

@@ -478,6 +478,69 @@ def Vector_ShuffleOp :
   let hasCanonicalizer = 1;
 }
 
+def Vector_InterleaveOp :
+  Vector_Op<"interleave", [Pure,
+    AllTypesMatch<["lhs", "rhs"]>,
+    TypesMatchWith<
+    "type of 'result' is double the width of the inputs",
+    "lhs", "result",
+    [{
+      [&]() -> ::mlir::VectorType {
+        auto vectorType = ::llvm::cast<mlir::VectorType>($_self);
+        ::mlir::VectorType::Builder builder(vectorType);
+        if (vectorType.getRank() == 0) {
+          static constexpr int64_t v2xty_shape[] = { 2 };
+          return builder.setShape(v2xty_shape);
+        }
+        auto lastDim = vectorType.getRank() - 1;
+        return builder.setDim(lastDim, vectorType.getDimSize(lastDim) * 2);
+      }()
+    }]>]> {
+  let summary = "constructs a vector by interleaving two input vectors";
+  let description = [{
+    The interleave operation constructs a new vector by interleaving the
+    elements from the trailing (or final) dimension of two input vectors,
+    returning a new vector where the trailing dimension is twice the size.
+
+    Note that for the n-D case this differs from the interleaving possible with
+    `vector.shuffle`, which would only operate on the leading dimension.
+
+    Another key difference is this operation supports scalable vectors, though
+    currently a general LLVM lowering is limited to the case where only the
+    trailing dimension is scalable.
+
+    Example:
+    ```mlir
+    %0 = vector.interleave %a, %b
+               : vector<[4]xi32>     ; yields vector<[8]xi32>
+    %1 = vector.interleave %c, %d
+               : vector<8xi8>        ; yields vector<16xi8>
+    %2 = vector.interleave %e, %f
+               : vector<f16>         ; yields vector<2xf16>
+    %3 = vector.interleave %g, %h
+               : vector<2x4x[2]xf64> ; yields vector<2x4x[4]xf64>
+    %4 = vector.interleave %i, %j
+               : vector<6x3xf32>     ; yields vector<6x6xf32>
+    ```
+  }];
+
+  let arguments = (ins AnyVectorOfAnyRank:$lhs, AnyVectorOfAnyRank:$rhs);
+  let results = (outs AnyVector:$result);
+
+  let assemblyFormat = [{
+    $lhs `,` $rhs  attr-dict `:` type($lhs)
+  }];
+
+  let extraClassDeclaration = [{
+    VectorType getSourceVectorType() {
+      return ::llvm::cast<VectorType>(getLhs().getType());
+    }
+    VectorType getResultVectorType() {
+      return ::llvm::cast<VectorType>(getResult().getType());
+    }
+  }];
+}
+
 def Vector_ExtractElementOp :
   Vector_Op<"extractelement", [Pure,
      TypesMatchWith<"result type matches element type of vector operand",

mlir/test/Dialect/Vector/ops.mlir

@@ -1081,3 +1081,38 @@ func.func @fastmath(%x: vector<42xf32>) -> f32 {
   %min = vector.reduction <minnumf>, %x fastmath<reassoc,nnan,ninf> : vector<42xf32> into f32
   return %min: f32
 }
+
+// CHECK-LABEL: @interleave_0d
+func.func @interleave_0d(%a: vector<f32>, %b: vector<f32>) -> vector<2xf32> {
+  // CHECK: vector.interleave %{{.*}}, %{{.*}} : vector<f32>
+  %0 = vector.interleave %a, %b : vector<f32>
+  return %0 : vector<2xf32>
+}
+
+// CHECK-LABEL: @interleave_1d
+func.func @interleave_1d(%a: vector<4xf32>, %b: vector<4xf32>) -> vector<8xf32> {
+  // CHECK: vector.interleave %{{.*}}, %{{.*}} : vector<4xf32>
+  %0 = vector.interleave %a, %b : vector<4xf32>
+  return %0 : vector<8xf32>
+}
+
+// CHECK-LABEL: @interleave_1d_scalable
+func.func @interleave_1d_scalable(%a: vector<[8]xi16>, %b: vector<[8]xi16>) -> vector<[16]xi16> {
+  // CHECK: vector.interleave %{{.*}}, %{{.*}} : vector<[8]xi16>
+  %0 = vector.interleave %a, %b : vector<[8]xi16>
+  return %0 : vector<[16]xi16>
+}
+
+// CHECK-LABEL: @interleave_2d
+func.func @interleave_2d(%a: vector<2x8xf32>, %b: vector<2x8xf32>) -> vector<2x16xf32> {
+  // CHECK: vector.interleave %{{.*}}, %{{.*}} : vector<2x8xf32>
+  %0 = vector.interleave %a, %b : vector<2x8xf32>
+  return %0 : vector<2x16xf32>
+}
+
+// CHECK-LABEL: @interleave_2d_scalable
+func.func @interleave_2d_scalable(%a: vector<2x[2]xf64>, %b: vector<2x[2]xf64>) -> vector<2x[4]xf64> {
+  // CHECK: vector.interleave %{{.*}}, %{{.*}} : vector<2x[2]xf64>
+  %0 = vector.interleave %a, %b : vector<2x[2]xf64>
+  return %0 : vector<2x[4]xf64>
+}