[Mlir-commits] [mlir] [MLIR] Add pattern to bubble up tensor.extract_slice (PR #126898)

[Andrzej Warzyński]

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@@ -210,6 +214,217 @@ struct BubbleUpExpandThroughParallelCollapse
   }
 };
 
+/// Converts `tensor.extract_slice(tensor.expand_shape)` to
+/// `tensor.expand_shape(tensor.extract_slice)`.
+/// For this transformation to be possible, the slice must be fully contiguous
+/// within each reassociation group of the expand_shape.
+/// A slice is defined as fully contiguous within a reassociation group if after
+/// flattening the reassociation group to a single 1D range, then the slice
+/// taken out of the group could be defined as a single contiguous subrange
+/// within that range.
+/// If the transformation is not possible, or if the slice is rank reducing, the
+/// function returns failure.
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banach-space wrote:

This is a great summary, but I think that you can reformat a bit to improve the flow.

* Added empty lines.
* Trimmed the last sentence to "Rank reducing slices are not supported." (from what I can tell, the meaning has been preserved)
```suggestion
/// Converts `tensor.extract_slice(tensor.expand_shape)` to
/// `tensor.expand_shape(tensor.extract_slice)`.
///
/// For this transformation to be possible, the slice must be fully contiguous
/// within each reassociation group of the expand_shape. A slice is defined as
/// fully contiguous within a reassociation group if after flattening the
/// reassociation group to a single 1D range, then the slice taken out of the
/// group could be defined as a single contiguous subrange within that range.
///
/// Rank reducing slices are not supported.
```

https://github.com/llvm/llvm-project/pull/126898