[inductor] Fix CPP wrapper codegen for ExternKernel args (#117931)

Summary:

Recently, this has been fixed for the Python wrapper codegen in D52899373 (#117838). Here we extend the fix to CPP wrapper codegen / AOTInductor.

Test Plan:
New unit tests. In OSS:

```
python test/inductor/test_aot_inductor.py -k test_triton_kernel_multi_output_arg
```

```
python test/inductor/test_aot_inductor.py -k test_triton_kernel_extern_kernel_arg
```

Differential Revision: D52936248

test/inductor/test_aot_inductor.py

@@ -1575,6 +1575,42 @@ def forward(self, a):
         model.weight += 1
         self.check_model(model, example_inputs)
 
+    def test_triton_kernel_extern_kernel_arg(self):
+        if self.device != "cuda":
+            raise unittest.SkipTest("requires CUDA")
+
+        class Model(torch.nn.Module):
+            def forward(self, x, y):
+                out = torch.zeros_like(x)
+                # torch.mm is ExternKernelOut
+                add_kernel[(4,)](x, torch.mm(x, y), out, 4, 16)
+                return out
+
+        example_inputs = (
+            torch.randn(4, 4, device="cuda"),
+            torch.randn(4, 4, device="cuda"),
+        )
+
+        self.check_model(Model(), example_inputs)
+
+    def test_triton_kernel_multi_output_arg(self):
+        if self.device != "cuda":
+            raise unittest.SkipTest("requires CUDA")
+
+        class Model(torch.nn.Module):
+            def forward(self, x, y):
+                out = torch.zeros_like(x)
+                # torch.sort creates fallback kernel and hence MultiOutput
+                add_kernel[(4,)](x, torch.sort(y).values, out, 4, 16)
+                return out
+
+        example_inputs = (
+            torch.randn(4, 4, device="cuda"),
+            torch.randn(4, 4, device="cuda"),
+        )
+
+        self.check_model(Model(), example_inputs)
+
 
 common_utils.instantiate_parametrized_tests(AOTInductorTestsTemplate)
 
@@ -1673,6 +1709,8 @@ def fail_abi_compatible_cuda(is_skip=False):
     "test_normal_functional": fail_abi_compatible_cuda(),
     # There is a double-free issue which will be fixed in another PR
     "test_repeat_output": fail_abi_compatible_cuda(is_skip=True),
+    # no ABI shim fn for torch.sort; remove this when adding one
+    "test_triton_kernel_multi_output_arg": fail_abi_compatible_cuda(),
 }
 
 if TEST_WITH_ROCM:

torch/_inductor/codegen/wrapper.py

@@ -23,7 +23,7 @@
 
 from .. import codecache, config, ir
 from ..codecache import CudaKernelParamCache
-from ..ir import ComputedBuffer, InputBuffer, ReinterpretView
+from ..ir import ReinterpretView
 from ..triton_heuristics import grid as default_grid
 from ..utils import (
     cache_on_self,
@@ -1147,7 +1147,7 @@ def __repr__(self):
             return repr(type(s)(Shim(self.val_to_arg_str(a)) for a in s))
         elif isinstance(s, torch._ops.OpOverload):
             return _get_qualified_name(s)
-        elif isinstance(s, (ir.Buffer, ComputedBuffer, InputBuffer, ReinterpretView)):
+        elif isinstance(s, (ir.Buffer, ReinterpretView)):
             return s.codegen_reference()
         else:
             return repr(s)
@@ -2788,7 +2788,7 @@ def val_to_arg_str(self, val) -> str:
             return f"{val}L"
         elif isinstance(val, str):
             return f'"{val}"'
-        elif isinstance(val, (ComputedBuffer, InputBuffer, ReinterpretView)):
+        elif isinstance(val, (ir.Buffer, ReinterpretView)):
             return val.codegen_reference()
         elif isinstance(val, torch.device):
             return self.codegen_device(val)