[mlir][bufferization] Fix bug in findValueInReverseUseDefChain

[springerm]

Summary

alwaysIncludeLeaves was not respected by all code paths.

[nicolasvasilache]

mlir/test/Dialect/Bufferization/Transforms/one-shot-bufferize-empty-tensor-elimination.mlir

224

nit: nl

mlir/lib/Dialect/Bufferization/IR/BufferizableOpInterface.cpp

if (!bufferizableOp || aliases.getNumAliases() == 0) {
         result.insert(value);
       continue;
     }
 
     for (AliasingOpOperand a : aliases) {
       if (followEquivalentOnly && a.relation != BufferRelation::Equivalent) {
         // Stop iterating if `followEquivalentOnly` is set but the alias is not
         // equivalent.
+        if (alwaysIncludeLeaves)
           result.insert(value);
       } else {
         workingSet.insert(a.opOperand->get());
       }
     }
   }
 
   return result;
 }

mlir/test/Dialect/Bufferization/Transforms/one-shot-bufferize-empty-tensor-elimination.mlir

func.func @eleminate_multiple_ops(%t: tensor<?xf32> {bufferization.buffer_layout = affine_map<(d0) -> (d0)>}, %sz: index, %c: i1)
   }
 
   // Self-copy could canonicalize away later.
   // CHECK: %[[T_SUBVIEW_3:.*]] =  memref.subview %[[FUNC_ARG]][42] [%[[sz]]] [1]
   // CHECK: memref.copy %[[r]], %[[T_SUBVIEW_3]]
   %r1 = tensor.insert_slice %if into %t[42][%sz][1]: tensor<?xf32> into tensor<?xf32>
   return %r1: tensor<?xf32>
 }
+
+// -----
+
+// This is a regression test. Make sure that the tensor.extract_slice is not
+// eliminated.
+
+// CHECK-LABEL: func.func @regression_do_not_eliminate_non_empty(
+//       CHECK:   memref.subview
+//       CHECK:   memref.subview
+//       CHECK:   memref.copy
+func.func @regression_do_not_eliminate_non_empty(
+    %t: tensor<10xf32>, %t2: tensor<10xf32>) -> tensor<10xf32> {
+  %1 = tensor.extract_slice %t[0] [5] [1] : tensor<10xf32> to tensor<5xf32>
+  %2 = tensor.insert_slice %1 into %t2[1] [5] [1]
+      : tensor<5xf32> into tensor<10xf32>
+  return %2 : tensor<10xf32>
+}
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