[LINALG] Add support for preserve memory format in aten_empty_like op.

The preserve memory specifies that `If any of the input tensors is in channels_last format,
operator output should be in channels_last format` and hence can be
added as is in aten_empty_like op.

lib/Conversion/TorchToLinalg/TensorConstructors.cpp

@@ -196,13 +196,19 @@ public:
       return rewriter.notifyMatchFailure(
           op, "unimplemented: pin_memory must be either None or false");
 
-    // Only `none` and `contiguous` memory_format is supported.
-    int64_t memoryFormat;
-    if (!op.memory_format().getType().isa<Torch::NoneType>() &&
-        (!matchPattern(op.memory_format(), m_TorchConstantInt(&memoryFormat)) ||
-         memoryFormat != torch_upstream::MemoryFormat::Contiguous))
-      return rewriter.notifyMatchFailure(
-          op, "unimplemented: only default memory format is supported");
+    // Only `none`, `contiguous` and `preserve` memory_format is supported.
+    if (!op.memory_format().getType().isa<Torch::NoneType>()) {
+      int64_t memoryFormat;
+      if (!matchPattern(op.memory_format(), m_TorchConstantInt(&memoryFormat)))
+        return rewriter.notifyMatchFailure(
+            op, "unimplemented: the memory format should be specified in "
+                "an integer constant");
+      if (memoryFormat != torch_upstream::MemoryFormat::Contiguous &&
+          memoryFormat != torch_upstream::MemoryFormat::Preserve)
+        return rewriter.notifyMatchFailure(
+            op, "unimplemented: only none, contiguous and preserve "
+                "memory_format is supported");
+    }
 
     Location loc = op.getLoc();
     TypeConverter *typeConverter = this->getTypeConverter();

python/torch_mlir_e2e_test/test_suite/constant_alloc.py

@@ -331,6 +331,25 @@ def EmptyLikeModule_int(module, tu: TestUtils):
     module.forward(torch.randint(10, (3, 5)))
 
 
+class EmptyLikeMemoryFormatModule(torch.nn.Module):
+
+    def __init__(self):
+        super().__init__()
+
+    @export
+    @annotate_args([
+        None,
+        ([-1, -1, -1, -1], torch.float32, True),
+    ])
+    def forward(self, a):
+        return torch.empty_like(a, memory_format=torch.preserve_format).fill_(0)
+
+
+@register_test_case(module_factory=lambda: EmptyLikeMemoryFormatModule())
+def EmptyLikeMemoryFormatModule_basic(module, tu: TestUtils):
+    module.forward(tu.rand(3, 5, 2, 1))
+
+
 class EmptyLikeFloatModule(torch.nn.Module):
 
     def __init__(self):