[mlir][memref] Remove invalid extract_aligned_pointer_as_index folding in ExpandStridedMetadata (llvm#167615)

`RewriteExtractAlignedPointerAsIndexOfViewLikeOp` tries to propagate
`extract_aligned_pointer_as_index` through the view ops.

`ViewLikeOpInterface` by itself doesn't guarantee to preserve the base
pointer and `memref.view` is one such example, so limit pattern to a few
specific ops.

Author: Hardcode84

mlir/lib/Dialect/MemRef/Transforms/ExpandStridedMetadata.cpp

@@ -959,7 +959,11 @@ class RewriteExtractAlignedPointerAsIndexOfViewLikeOp
                   PatternRewriter &rewriter) const override {
     auto viewLikeOp =
         extractOp.getSource().getDefiningOp<ViewLikeOpInterface>();
-    if (!viewLikeOp || extractOp.getSource() != viewLikeOp.getViewDest())
+    // ViewLikeOpInterface by itself doesn't guarantee to preserve the base
+    // pointer in general and `memref.view` is one such example, so just check
+    // for a few specific cases.
+    if (!viewLikeOp || extractOp.getSource() != viewLikeOp.getViewDest() ||
+        !isa<memref::SubViewOp, memref::ReinterpretCastOp>(viewLikeOp))
       return rewriter.notifyMatchFailure(extractOp, "not a ViewLike source");
     rewriter.modifyOpInPlace(extractOp, [&]() {
       extractOp.getSourceMutable().assign(viewLikeOp.getViewSource());

mlir/test/Dialect/MemRef/expand-strided-metadata.mlir

@@ -1455,3 +1455,20 @@ func.func @extract_strided_metadata_of_memory_space_cast_no_base(%base: memref<2
 
 // CHECK-LABEL:  func @extract_strided_metadata_of_memory_space_cast_no_base
 //   CHECK-NOT:  memref.memory_space_cast
+
+// -----
+
+func.func @negative_memref_view_extract_aligned_pointer(%arg0: memref<?xi8>) -> index {
+  // `extract_aligned_pointer_as_index` must not be folded as `memref.view` can change the base pointer
+  // CHECK-LABEL: func @negative_memref_view_extract_aligned_pointer
+  // CHECK-SAME: (%[[ARG0:.*]]: memref<?xi8>)
+  // CHECK: %[[C10:.*]] = arith.constant 10 : index
+  // CHECK: %[[VIEW:.*]] = memref.view %[[ARG0]][%[[C10]]][] : memref<?xi8> to memref<f32>
+  // CHECK: %[[PTR:.*]] = memref.extract_aligned_pointer_as_index %[[VIEW]] : memref<f32> -> index
+  // CHECK: return %[[PTR]] : index
+
+  %c10 = arith.constant 10 : index
+  %0 = memref.view %arg0[%c10][] : memref<?xi8> to memref<f32>
+  %1 = memref.extract_aligned_pointer_as_index %0: memref<f32> -> index
+  return %1 : index
+}