Enable Workspace sharing by default (#5336)

Summary:
Pull Request resolved: #5336

as Title

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Reviewed By: kimishpatel, GregoryComer

Differential Revision: D62598508

fbshipit-source-id: 6d2e6c36adb6365ba55c50fc99ca8a4562280a50

Author: digantdesai

backends/xnnpack/CMakeLists.txt

@@ -32,10 +32,10 @@ if(NOT PYTHON_EXECUTABLE)
   resolve_python_executable()
 endif()
 
-# NB: Enabling this will serialize execution of delegate instances Keeping this
-# OFF by default to maintain existing behavior, to be revisited.
+# NB: Enabling this will serialize execution of delegate instances.
+# This setting may have performance implications.
 option(EXECUTORCH_XNNPACK_SHARED_WORKSPACE
-       "Enable workspace sharing across different delegate instances" OFF
+       "Enable workspace sharing across different delegate instances" ON
 )
 if(EXECUTORCH_XNNPACK_SHARED_WORKSPACE)
   add_definitions(-DENABLE_XNNPACK_SHARED_WORKSPACE)

backends/xnnpack/targets.bzl

@@ -36,10 +36,10 @@ def define_common_targets():
             "@EXECUTORCH_CLIENTS",
         ],
         preprocessor_flags = [
+            # Enable workspace sharing across delegates
+            "-DENABLE_XNNPACK_SHARED_WORKSPACE",
             # Uncomment to enable per operator timings
             # "-DENABLE_XNNPACK_PROFILING",
-            # Uncomment to enable workspace sharing across delegates
-            # "-DENABLE_XNNPACK_SHARED_WORKSPACE"
         ],
         exported_deps = [
             "//executorch/runtime/backend:interface",