Update on "Integrate torchgen exception boundary with ExecuTorch"

As of #7746, we build with exceptions by default, so we just need to use them.

TODO: presumably we need to manage rollout of the torchgen patch?

Differential Revision: [D67904052](https://our.internmc.facebook.com/intern/diff/D67904052/)

[ghstack-poisoned]

Author: swolchok

shim/xplat/executorch/codegen/codegen.bzl

@@ -116,7 +116,8 @@ def _prepare_genrule_and_lib(
         custom_ops_yaml_path = None,
         custom_ops_requires_runtime_registration = True,
         manual_registration = False,
-        aten_mode = False):
+        aten_mode = False,
+        support_exceptions = True):
     """
     This function returns two dicts `genrules` and `libs`, derived from the arguments being passed
     to `executorch_generated_lib`. `genrules` contains all information related to what genrules to
@@ -151,12 +152,15 @@ def _prepare_genrule_and_lib(
         "--source-path=$(location //executorch/codegen:templates)",
         "--tags-path $(location {})/aten/src/ATen/native/tags.yaml".format(aten_src_path),
         "--aten_yaml_path $(location {})/aten/src/ATen/native/native_functions.yaml".format(aten_src_path),
-        "--add-exception-boundary",
         "--install_dir=${OUT}",
         # TODO(dbort): Add a second step that verifies that the set of
         # actually-generated files matches GENERATED_FILES.
     ]
 
+    if support_exceptions:
+        genrule_cmd.append("--add-exception-boundary")
+
+
     # Sources for generated kernel registration lib
     sources = MANUAL_REGISTRATION_SOURCES if manual_registration else GENERATED_SOURCES
 
@@ -218,6 +222,7 @@ def _prepare_genrule_and_lib(
 def _prepare_custom_ops_genrule_and_lib(
         name,
         custom_ops_yaml_path = None,
+        support_exceptions = True,
         deps = [],
         kernels = []):
     """Similar to _prepare_genrule_and_lib but for custom ops."""
@@ -248,10 +253,11 @@ def _prepare_custom_ops_genrule_and_lib(
             "--tags-path $(location {})/aten/src/ATen/native/tags.yaml".format(aten_src_path),
             "--aten_yaml_path $(location {})/aten/src/ATen/native/native_functions.yaml".format(aten_src_path),
             "--custom_ops_yaml_path=" + custom_ops_yaml_path,
-            "--add_exception_boundary",
             "--install_dir=${OUT}",
             "--op_selection_yaml_path=$(location :{}[selected_operators.yaml])".format(oplist_dir_name),
         ]
+        if support_exceptions:
+            genrule_cmd.append("--add-exception-boundary")
 
         # Determine what sources custom_ops_<name> target should include
         custom_ops_sources = CUSTOM_OPS_SCHEMA_REGISTRATION_SOURCES + (
@@ -283,6 +289,7 @@ def exir_custom_ops_aot_lib(
         deps = [],
         compiler_flags = [],
         define_static_target = False,
+        support_exceptions = True,
         platforms = get_default_executorch_platforms()):
     """Generates a C++ library that helps to register the custom ops into PyTorch,
     so they are visible to EXIR. To use this, we need to load the generated so file:
@@ -299,11 +306,13 @@ def exir_custom_ops_aot_lib(
         visibility: visibility of the generated library.
         kernels: C++ kernels for these custom ops. They need to be implemented using ATen/c10 basics.
         deps: dependencies of the generated library.
+        support_exceptions: enable try/catch wrapper around operator implemntations to make sure exceptions thrown will not bring down the process. Disable if your use case disables exceptions in the build.
     """
     genrules, libs = _prepare_custom_ops_genrule_and_lib(
         name = name,
         custom_ops_yaml_path = selects.apply(yaml_target, lambda y: "$(location {})".format(y)),
         kernels = kernels,
+        support_exceptions = support_exceptions,
         deps = deps,
     )
     for genrule in genrules:
@@ -448,7 +457,8 @@ def executorch_generated_lib(
         kernel_deps = [],
         dtype_selective_build = False,
         feature = None,
-        expose_operator_symbols = False):
+        expose_operator_symbols = False,
+        support_exceptions = True):
     """Emits 0-3 C++ library targets (in fbcode or xplat) containing code to
     dispatch the operators specified in the provided yaml files.
 
@@ -497,6 +507,7 @@ def executorch_generated_lib(
         compiler_flags: compiler_flags args to runtime.cxx_library
         dtype_selective_build: In additional to operator selection, dtype selective build further selects the dtypes for each operator. Can be used with model or dict selective build APIs, where dtypes can be specified. Note: this is only available in xplat.
         feature: Product-Feature Hierarchy (PFH). For internal use only, required for FoA in production. See: https://fburl.com/wiki/2wzjpyqy
+        support_exceptions: enable try/catch wrapper around operator implemntations to make sure exceptions thrown will not bring down the process. Disable if your use case disables exceptions in the build.
     """
     if functions_yaml_target and aten_mode:
         fail("{} is providing functions_yaml_target in ATen mode, it will be ignored. `native_functions.yaml` will be the source of truth.".format(name))
@@ -536,6 +547,7 @@ def executorch_generated_lib(
         custom_ops_requires_runtime_registration = custom_ops_requires_runtime_registration,
         aten_mode = aten_mode,
         manual_registration = manual_registration,
+        support_exceptions = support_exceptions,
     )
 
     # genrule for selective build from static operator list