[mlir][vector] Add vector.transpose with unit-dim to vector.shape_cas…

…t pattern (llvm#72105)

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.

mlir/lib/Dialect/Vector/Transforms/LowerVectorTranspose.cpp

@@ -336,6 +336,27 @@ class TransposeOpLowering : public OpRewritePattern<vector::TransposeOp> {
  return rewriter.notifyMatchFailure(
  op, "Options specifies lowering to shuffle");
 
+ // Replace:
+ // vector.transpose %0, [1, 0] : vector<nx1x<eltty>> to
+ // vector<1xnxelty>
+ // with:
+ // vector.shape_cast %0 : vector<nx1x<eltty>> to vector<1xnxelty>
+ //
+ // Source with leading unit dim (inverse) is also replaced. Unit dim must
+ // be fixed. Non-unit can be scalable.
+ if (resType.getRank() == 2 &&
+ ((resType.getShape().front() == 1 &&
+ !resType.getScalableDims().front()) ||
+ (resType.getShape().back() == 1 &&
+ !resType.getScalableDims().back())) &&
+ transp == ArrayRef<int64_t>({1, 0})) {
+ rewriter.replaceOpWithNewOp<vector::ShapeCastOp>(op, resType, input);
+ return success();
+ }
+
+ if (inputType.isScalable())
+ return failure();
+
  // Handle a true 2-D matrix transpose differently when requested.
  if (vectorTransformOptions.vectorTransposeLowering ==
  vector::VectorTransposeLowering::Flat &&

mlir/test/Dialect/Vector/vector-transpose-lowering.mlir

@@ -74,6 +74,17 @@ func.func @transpose1023_1x1x8x8xf32(%arg0: vector<1x1x8x8xf32>) -> vector<1x1x8
  return %0 : vector<1x1x8x8xf32>
 }
 
+/// Scalable dim should not be unrolled.
+
+// CHECK-LABEL: func @transpose23_scalable
+// CHECK-NOT: vector.extract
+// CHECK-NOT: vector.insert
+// CHECK: vector.transpose
+func.func @transpose23_scalable(%arg0: vector<2x[3]xf32>) -> vector<[3]x2xf32> {
+ %0 = vector.transpose %arg0, [1, 0] : vector<2x[3]xf32> to vector<[3]x2xf32>
+ return %0 : vector<[3]x2xf32>
+}
+
 module attributes {transform.with_named_sequence} {
  transform.named_sequence @__transform_main(%func_op: !transform.op<"func.func"> {transform.readonly}) {
  transform.apply_patterns to %func_op {
@@ -778,3 +789,63 @@ module attributes {transform.with_named_sequence} {
  transform.yield
  }
 }
+
+// -----
+
+/// Transpose of rank-2 vector with leading or trailing unit dim to shape_cast.
+
+// CHECK-LABEL: func @transpose10_4x1xf32
+func.func @transpose10_4x1xf32(%arg0: vector<4x1xf32>) -> vector<1x4xf32> {
+ // CHECK-NEXT: vector.shape_cast %{{.*}} : vector<4x1xf32> to vector<1x4xf32>
+ %0 = vector.transpose %arg0, [1, 0] : vector<4x1xf32> to vector<1x4xf32>
+ return %0 : vector<1x4xf32>
+}
+
+// CHECK-LABEL: func @transpose10_nx4x1xf32
+func.func @transpose10_nx4x1xf32(%arg0: vector<[4]x1xf32>) -> vector<1x[4]xf32> {
+ // CHECK-NEXT: vector.shape_cast %{{.*}} : vector<[4]x1xf32> to vector<1x[4]xf32>
+ %0 = vector.transpose %arg0, [1, 0] : vector<[4]x1xf32> to vector<1x[4]xf32>
+ return %0 : vector<1x[4]xf32>
+}
+
+// CHECK-LABEL: func @transpose10_1x4xf32
+func.func @transpose10_1x4xf32(%arg0: vector<1x4xf32>) -> vector<4x1xf32> {
+ // CHECK-NEXT: vector.shape_cast %{{.*}} : vector<1x4xf32> to vector<4x1xf32>
+ %0 = vector.transpose %arg0, [1, 0] : vector<1x4xf32> to vector<4x1xf32>
+ return %0 : vector<4x1xf32>
+}
+
+// CHECK-LABEL: func @transpose10_1xnx4xf32
+func.func @transpose10_1xnx4xf32(%arg0: vector<1x[4]xf32>) -> vector<[4]x1xf32> {
+ // CHECK-NEXT: vector.shape_cast %{{.*}} : vector<1x[4]xf32> to vector<[4]x1xf32>
+ %0 = vector.transpose %arg0, [1, 0] : vector<1x[4]xf32> to vector<[4]x1xf32>
+ return %0 : vector<[4]x1xf32>
+}
+
+/// Scalable unit dim should not be lowered to shape_cast.
+
+// CHECK-LABEL: func @transpose10_4xnx1xf32
+func.func @transpose10_4xnx1xf32(%arg0: vector<4x[1]xf32>) -> vector<[1]x4xf32> {
+ // CHECK-NOT: vector.shape_cast
+ // CHECK: vector.transpose %{{.*}} : vector<4x[1]xf32> to vector<[1]x4xf32>
+ %0 = vector.transpose %arg0, [1, 0] : vector<4x[1]xf32> to vector<[1]x4xf32>
+ return %0 : vector<[1]x4xf32>
+}
+
+// CHECK-LABEL: func @transpose10_nx4xnx1xf32
+func.func @transpose10_nx4xnx1xf32(%arg0: vector<4x[1]xf32>) -> vector<[1]x4xf32> {
+ // CHECK-NOT: vector.shape_cast
+ // CHECK: vector.transpose %{{.*}} : vector<4x[1]xf32> to vector<[1]x4xf32>
+ %0 = vector.transpose %arg0, [1, 0] : vector<4x[1]xf32> to vector<[1]x4xf32>
+
+ return %0 : vector<[1]x4xf32>
+}
+
+module attributes {transform.with_named_sequence} {
+ transform.named_sequence @__transform_main(%func_op: !transform.op<"func.func"> {transform.readonly}) {
+ transform.apply_patterns to %func_op {
+ transform.apply_patterns.vector.lower_transpose
+ } : !transform.op<"func.func">
+ transform.yield
+ }
+}