[mlir][vector][nfc] Rename populateVectorTransferCollapseInnerMostContiguousDimsPatterns (#145228)

Renames `populateVectorTransferCollapseInnerMostContiguousDimsPatterns`
as `populateDropInnerMostUnitDimsXferOpPatterns` + updates the
corresponding comments.

This addresses a TODO and makes the difference between these two
`populate*` methods clearer:
 * `populateDropUnitDimWithShapeCastPatterns`,
 * `populateDropInnerMostUnitDimsXferOpPatterns`.

mlir/include/mlir/Dialect/Vector/Transforms/VectorRewritePatterns.h

@@ -137,12 +137,14 @@ void populateVectorReductionToContractPatterns(RewritePatternSet &patterns,
 void populateVectorTransferFullPartialPatterns(
     RewritePatternSet &patterns, const VectorTransformsOptions &options);
 
-/// Collect a set of patterns to reduce the rank of the operands of vector
-/// transfer ops to operate on the largest contigious vector.
-/// These patterns are useful when lowering to dialects with 1d vector type
-/// such as llvm and it will result fewer memory reads.
-void populateVectorTransferCollapseInnerMostContiguousDimsPatterns(
-    RewritePatternSet &patterns, PatternBenefit benefit = 1);
+/// Collect a set of patterns to collapse the most inner unit dims in xfer Ops
+///
+/// These patters reduce the rank of the operands of vector transfer ops to
+/// operate on vectors without trailing unit dims. This helps reduce the rank of
+/// the operands, which can be helpful when lowering to dialects that only
+/// support 1D vector type such as LLVM.
+void populateDropInnerMostUnitDimsXferOpPatterns(RewritePatternSet &patterns,
+                                                 PatternBenefit benefit = 1);
 
 /// Patterns that remove redundant Vector Ops by re-ordering them with
 /// e.g. elementwise Ops:

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

@@ -2266,11 +2266,6 @@ void mlir::vector::populateVectorMaskMaterializationPatterns(
 
 void mlir::vector::populateDropUnitDimWithShapeCastPatterns(
     RewritePatternSet &patterns, PatternBenefit benefit) {
-  // TODO: Consider either:
-  //  * including DropInnerMostUnitDimsTransferRead and
-  //    DropInnerMostUnitDimsTransferWrite, or
-  //  * better naming to distinguish this and
-  //    populateVectorTransferCollapseInnerMostContiguousDimsPatterns.
   patterns.add<DropUnitDimFromElementwiseOps, DropUnitDimsFromScfForOp,
                DropUnitDimsFromTransposeOp>(patterns.getContext(), benefit);
 }
@@ -2305,9 +2300,8 @@ void mlir::vector::populateVectorReductionToContractPatterns(
       patterns.getContext(), benefit);
 }
 
-void mlir::vector::
-    populateVectorTransferCollapseInnerMostContiguousDimsPatterns(
-        RewritePatternSet &patterns, PatternBenefit benefit) {
+void mlir::vector::populateDropInnerMostUnitDimsXferOpPatterns(
+    RewritePatternSet &patterns, PatternBenefit benefit) {
   patterns.add<DropInnerMostUnitDimsTransferRead,
                DropInnerMostUnitDimsTransferWrite>(patterns.getContext(),
                                                    benefit);

mlir/test/lib/Dialect/Vector/TestVectorTransforms.cpp

@@ -369,7 +369,7 @@ struct TestVectorTransferCollapseInnerMostContiguousDims
 
   void runOnOperation() override {
     RewritePatternSet patterns(&getContext());
-    populateVectorTransferCollapseInnerMostContiguousDimsPatterns(patterns);
+    populateDropInnerMostUnitDimsXferOpPatterns(patterns);
     (void)applyPatternsGreedily(getOperation(), std::move(patterns));
   }
 };