[mlir][tensor][bufferize] tensor.empty does not define the result tensor contents

[springerm]

Summary

This is encoded in the BufferizableOpInterface via resultBufferizesToMemoryWrite = false.

mlir/lib/Dialect/Tensor/Transforms/BufferizableOpInterfaceImpl.cpp

 
 /// Bufferization of tensor.empty. This op does not bufferize, but we need an
 /// interface implementation, so that the result of this op is considered
 /// "writable" (default impl. of `isWritable`). Results of ops that do not
 /// implement `BufferizableOpInterface` are not writable.
 struct EmptyOpInterface
     : public BufferizableOpInterface::ExternalModel<EmptyOpInterface,
                                                     tensor::EmptyOp> {
+  bool resultBufferizesToMemoryWrite(Operation *op, OpResult opResult,
+                                     const AnalysisState &state) const {
+    // The returned tensor does not have specified contents.
+    return false;
+  }
+
   LogicalResult bufferize(Operation *op, RewriterBase &rewriter,
                           const BufferizationOptions &options) const {
     // tensor.empty ops are used to indicate the shape of a tensor. They have
     // no defined contents and cannot be bufferized. However, they can be
     // converted to bufferization.alloc_tensor ops, which then bufferize to an
     // allocation (--empty-tensor-to-alloc-tensor).
     return op->emitOpError("cannot be bufferized, but can be converted to "
                            "bufferization.alloc_tensor");