[mlir][linalg] Fix UnPackOp::getTiledOuterDims (#152960)

Fixes `getTiledOuterDims` by making sure that the `outer_dims_perm`
attribute from `linalg.unpack` is taken into account.

Fixes #152037

Author: banach-space

mlir/include/mlir/Dialect/Linalg/Transforms/Transforms.h

@@ -1690,7 +1690,7 @@ struct DecomposeOuterUnitDimsPackOpPattern
 /// Rewrites a linalg::UnPackOp into a sequence of rank-reduced
 ///   * tensor::ExtractSliceOp + linalg::TransposeOp + tensor::InsertSliceOp
 ///
-/// Requires that all the outer dims of the input linalg::PackOp are 1.
+/// Requires that all the tiled outer dims of the input linalg::PackOp are 1.
 ///
 /// Before:
 /// ```

mlir/lib/Dialect/Linalg/IR/LinalgOps.cpp

@@ -5767,11 +5767,18 @@ ArrayRef<int64_t> UnPackOp::getAllOuterDims() {
 
 SmallVector<int64_t> UnPackOp::getTiledOuterDims() {
   auto innerDimsPos = getInnerDimsPos();
-  auto packedShape = getSourceType().getShape();
+  SmallVector<int64_t> outerDims(getAllOuterDims());
   SmallVector<int64_t> res;
 
+  // Recover the original order of the outer dims.
+  SmallVector<int64_t> outerDimPermInv(getOuterDimsPerm());
+  invertPermutationVector(outerDimPermInv);
+  if (!outerDimPermInv.empty())
+    applyPermutationToVector(outerDims, outerDimPermInv);
+
+  // Collect the outer dims corresponding to the tilled inner dims.
   for (auto index : innerDimsPos)
-    res.push_back(packedShape[index]);
+    res.push_back(outerDims[index]);
 
   return res;
 }

mlir/test/Dialect/Linalg/decompose-unpack.mlir

@@ -203,3 +203,20 @@ func.func @unpack_with_non_trailing_dimensions_in_inner_dims(%arg0: tensor<1x1x1
 // CHECK-SAME:                      outs(%[[EMPTY]] : tensor<1x4xf32>) permutation = [1, 0]
 // CHECK:        %[[INSERT:.+]] = tensor.insert_slice %transposed into %[[DEST]][0, 0, 0] [1, 1, 4] [1, 1, 1] : tensor<1x4xf32> into tensor<1x1x4xf32>
 // CHECK:        return %[[INSERT]]
+
+// -----
+
+/// Note "126", which is a non-unit tile-outer-dim. This is not supported.
+
+func.func @negative_non_unit_tiled_outer_dim(%src: tensor<1x126x1x1x8xf32>, %dest: tensor<1x1x1x1001xf32>) -> tensor<1x1x1x1001xf32> {
+  %unpack = linalg.unpack %src
+    outer_dims_perm = [0, 3, 2, 1]
+    inner_dims_pos = [3]
+    inner_tiles = [8]
+    into %dest : tensor<1x126x1x1x8xf32>
+    -> tensor<1x1x1x1001xf32>
+
+  return %unpack : tensor<1x1x1x1001xf32>
+}
+// CHECK-LABEL: @negative_non_unit_tiled_outer_dim(
+// CHECK: linalg.unpack