[Mlir-commits] [mlir] [mlir][tensor] Add more tensor.extract_slice canonicalization (PR #212974)

[Matthias Springer]

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@@ -117,6 +117,36 @@ func.func @linalg_effects(
 
 // -----
 
+// CHECK-LABEL: func @fold_extract_slice_of_fill_of_empty
+//   CHECK-NOT:   tensor.extract_slice
+//       CHECK:   %[[EMPTY:.*]] = tensor.empty() : tensor<4096xf32>
+//       CHECK:   %[[FILL:.*]] = linalg.fill ins(%[[CST:.*]] : f32) outs(%[[EMPTY]] : tensor<4096xf32>) -> tensor<4096xf32>
+//       CHECK:   return %[[FILL]] : tensor<4096xf32>
+func.func @fold_extract_slice_of_fill_of_empty(%cst : f32) -> tensor<4096xf32> {
+  %empty = tensor.empty() : tensor<4096x1xf32>
+  %filled = linalg.fill ins(%cst : f32) outs(%empty : tensor<4096x1xf32>) -> tensor<4096x1xf32>
+  %slice = tensor.extract_slice %filled[0, 0] [4096, 1] [1, 1]
+    : tensor<4096x1xf32> to tensor<4096xf32>
+  return %slice : tensor<4096xf32>
+}
+
+// -----
+
+// CHECK-LABEL: func @fold_extract_slice_of_fill_of_empty_2d
+//   CHECK-NOT:   tensor.extract_slice
+//       CHECK:   %[[EMPTY:.*]] = tensor.empty() : tensor<32x48xf32>
+//       CHECK:   %[[FILL:.*]] = linalg.fill ins(%[[CST:.*]] : f32) outs(%[[EMPTY]] : tensor<32x48xf32>) -> tensor<32x48xf32>
+//       CHECK:   return %[[FILL]] : tensor<32x48xf32>
+func.func @fold_extract_slice_of_fill_of_empty_2d(%cst : f32) -> tensor<32x48xf32> {
+  %empty = tensor.empty() : tensor<64x96xf32>
+  %filled = linalg.fill ins(%cst : f32) outs(%empty : tensor<64x96xf32>) -> tensor<64x96xf32>
+  %slice = tensor.extract_slice %filled[0, 0] [32, 48] [1, 1]
----------------
matthias-springer wrote:

Note: These are valid canonicalization patterns, but such patterns will likely cause performance regressions in One-Shot Bufferize. The bufferizer is looking for extract_slice/insert_slice pairs.

Patterns like these here are would be a good candidate for `EmptyOpPatterns.cpp` etc. (Also see other files in the same directory.)

https://github.com/llvm/llvm-project/pull/212974