fix the example backend (#664)

Summary:

Fix the example backend, rename to ExampleBackend

Reviewed By: guangy10

Differential Revision: D50022692

Author: cccclai

backends/example/README.md

@@ -5,7 +5,7 @@ The folder structure incluces:
 - example_partitioner
 - example_backend
 - examples_operators. Assuming all of them can run in the example backend.
-    - The OpBase defined in op_base.py is just the draft idea, it can be defined more comprehensively depending tosa operator definitions
+    - The OpBase defined in op_base.py is just the draft idea, it can be defined more comprehensively depending example operator definitions
 - example_backend_delegate_passes. It includes passes that might be helpful in the backend. Right now there are two passes: merge_to_dim_pass.py and permute_memory_formats_pass.py. They are examples to show how to represent memory format permutation and how to represent operators with different memory format (like channel last)
     - merge_to_dim_pass.py only handles one merging cases. More cases need to be covered but should be straitforward.
 

backends/example/example_backend.py

@@ -23,13 +23,13 @@
 
 
 @final
-class TosaBackend(BackendDetails):
+class ExampleBackend(BackendDetails):
     @staticmethod
     def preprocess(
         edge_program: ExportedProgram,
         compile_specs: List[CompileSpec],
     ) -> PreprocessResult:
-        print("entering  the lowerable parts in TosaBackend.preprocess....")
+        print("entering  the lowerable parts in ExampleBackend.preprocess....")
 
         copy_edge_program = copy.deepcopy(edge_program)
         copy_edge_program._transform(

backends/example/example_partitioner.py

@@ -7,7 +7,7 @@
 from typing import Dict, final
 
 import torch
-from executorch.backends.example.example_backend import TosaBackend
+from executorch.backends.example.example_backend import ExampleBackend
 from executorch.backends.example.example_operators.ops import module_to_annotator
 from executorch.exir.backend.canonical_partitioners.pattern_op_partitioner import (
     generate_partitions_from_list_of_nodes,
@@ -32,7 +32,7 @@ class ExamplePartitioner(Partitioner):
 
     def __init__(self) -> None:
         self.patterns = module_to_annotator.keys()
-        self.delegation_spec = DelegationSpec(TosaBackend.__name__, [])
+        self.delegation_spec = DelegationSpec(ExampleBackend.__name__, [])
 
         class DequantQuantOperatorSupport(OperatorSupportBase):
             def is_node_supported(self, _submodules, node: torch.fx.Node) -> bool: