[mlir] Add missing patterns to linalg.decompose_pack_unpack TD Op (#121400)

This PR is a follow-up to #116373 and #116439, where a Transform Dialect
(TD) operation was introduced to collect patterns for decomposing
tensor.pack. The second patch renamed the patterns and the TD Op.
Originally, adding patterns for `tensor.unpack` was marked as a TODO,
which this PR addresses.

No new tests are introduced in this PR. Instead, existing tests from:

* "decompose-tensor-unpack.mlir"

are reused. To achieve this:

* The test is updated to use the TD operation
  `transform.apply_patterns.linalg.decompose_pack_unpack` instead of the
  flag `--test-linalg-transform-patterns="test-decompose-tensor-unpack"`,
  avoiding artificial tests created solely for the TD Op.
* The TD sequence is saved to a new file, "decompose_unpack.mlir", and
  preloaded using the option.

Author: banach-space

mlir/lib/Dialect/Linalg/Transforms/Transforms.cpp

@@ -1656,8 +1656,8 @@ void linalg::populateDecomposeConvolutionPatterns(RewritePatternSet &patterns,
 }
 
 void linalg::populateDecomposePackUnpackPatterns(RewritePatternSet &patterns) {
-  // TODO: Add and test patterns for tensor.unpack
   patterns.add<DecomposeOuterUnitDimsPackOpPattern>(patterns.getContext());
+  patterns.add<DecomposeOuterUnitDimsUnPackOpPattern>(patterns.getContext());
 }
 
 void linalg::populateDecomposePadPatterns(RewritePatternSet &patterns) {

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

@@ -1,4 +1,7 @@
-// RUN: mlir-opt -split-input-file --transform-interpreter --canonicalize --test-linalg-transform-patterns="test-decompose-tensor-unpack"  %s | FileCheck %s
+// RUN: mlir-opt -split-input-file -transform-interpreter --canonicalize \
+// RUN: -transform-preload-library='transform-library-paths=%p/td/decompose-unpack.mlir' \
+// RUN: -transform-interpreter=entry-point=decompose_unpack \
+// RUN: -transform-interpreter  %s | FileCheck %s
 
 func.func @KCRSsr_to_KCRS(%arg0: tensor<1x1x4x8x8x32xf32>, %arg1: tensor<1x1x128x64xf32>) -> tensor<1x1x128x64xf32> {
   %0 = tensor.unpack %arg0 inner_dims_pos = [3, 2] inner_tiles = [8, 32] into %arg1 : tensor<1x1x4x8x8x32xf32> -> tensor<1x1x128x64xf32>

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

@@ -1,4 +1,6 @@
-// RUN: mlir-opt -split-input-file --test-linalg-transform-patterns="test-decompose-tensor-unpack"  %s | FileCheck %s
+// RUN: mlir-opt -split-input-file \
+// RUN: -transform-preload-library='transform-library-paths=%p/td/decompose-unpack.mlir' \
+// RUN: -transform-interpreter=entry-point=decompose_unpack %s | FileCheck %s
 
 func.func @simple_KCRSsr_to_KCRS(%arg0: tensor<1x1x1x1x8x32xf32>, %arg1: tensor<1x1x32x8xf32>) -> tensor<1x1x32x8xf32> {
   %0 = tensor.unpack %arg0 inner_dims_pos = [3, 2] inner_tiles = [8, 32] into %arg1 : tensor<1x1x1x1x8x32xf32> -> tensor<1x1x32x8xf32>

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

@@ -0,0 +1,12 @@
+module @transforms attributes { transform.with_named_sequence } {
+  transform.named_sequence @decompose_unpack(%module: !transform.any_op {transform.readonly}) {
+    %pack = transform.structured.match ops{["tensor.unpack"]} in %module : (!transform.any_op) -> !transform.any_op
+
+    %1 = transform.get_parent_op %pack {isolated_from_above} : (!transform.any_op) -> !transform.any_op
+    transform.apply_patterns to %1 {
+      transform.apply_patterns.linalg.decompose_pack_unpack
+    } : !transform.any_op
+
+    transform.yield
+  }
+}