fix: structured inputs for CudaGraphsTorchTensorRTModule

Author: keehyuna

py/torch_tensorrt/dynamo/runtime/_CudaGraphsTorchTensorRTModule.py

@@ -1,16 +1,48 @@
 from __future__ import annotations
 
 import logging
-from typing import List, Optional, Sequence, Tuple
+from typing import Any, List, Optional, Sequence, Tuple
 
 import torch
 import torch_tensorrt
 from torch.fx.experimental.proxy_tensor import unset_fake_temporarily
+from torch.utils._pytree import tree_flatten, tree_map, tree_unflatten
 from torch_tensorrt.dynamo import partitioning
 
 logger = logging.getLogger(__name__)
 
 
+def _unflatten_inputs(
+    flattened_inputs: Sequence[torch_tensorrt.Input],
+    compiled_module: torch.fx.GraphModule,
+) -> Tuple[Any, Any]:
+    """
+    Process inputs using tree_unflatten and tree_map to reconstructe inputs
+
+    Args:
+        flattened_inputs: Flattened input tensors to process
+        compiled_module: The compiled GraphModule containing input specifications
+
+    Returns:
+        Tuple of (args, kwargs) containing reconstructed input tensors
+    """
+
+    def convert_input_to_cuda_tensor(input: Any) -> torch.Tensor:
+        if isinstance(input, torch_tensorrt.Input):
+            return input.torch_tensor.cuda()
+        else:
+            raise RuntimeError("Input is not a torch_tensorrt.Input")
+
+    # Reconstruct the (args, kwargs) structure that was flattened during export
+    pytree_inputs = tree_unflatten(flattened_inputs, compiled_module._in_spec)
+    # Apply the tensor creation to the reconstructed structure
+    processed_inputs = tree_map(convert_input_to_cuda_tensor, pytree_inputs)
+
+    # Since inputs were originally flattened from (args, kwargs),
+    # processed_inputs is now that same tuple structure
+    return processed_inputs[0], processed_inputs[1]
+
+
 class CudaGraphsTorchTensorRTModule(torch.nn.Module):  # type: ignore[misc]
     """This Wrapper runtime module is to record/replay whole cuda graph in sub modules
 
@@ -42,14 +74,15 @@ def warm_up(self) -> None:
         Warm up is necessary to ensure that memory allocations and initializations
         are not recorded in cuda graphs
         """
+
         with torch_tensorrt.logging.errors():
             with unset_fake_temporarily():
-                inputs_tensor = [spec.torch_tensor.cuda() for spec in self.inputs]
+                args, kwargs = _unflatten_inputs(self.inputs, self.compiled_module)
                 s = torch.cuda.Stream()
                 s.wait_stream(torch.cuda.current_stream())
                 with torch.cuda.stream(s):
                     for _ in range(3):
-                        self.compiled_module(*inputs_tensor)
+                        self.compiled_module(*args, **kwargs)
                 torch.cuda.current_stream().wait_stream(s)
 
     def validate_input_shapes(self, inputs: Sequence[torch.Tensor]) -> bool:
@@ -73,15 +106,18 @@ def __del__(self) -> None:
         if self.cudagraph:
             self.cudagraph.reset()
 
-    def forward(self, *inputs: torch.Tensor) -> torch.Tensor | Tuple[torch.Tensor, ...]:
+    def forward(
+        self, *args: Any, **kwargs: Any
+    ) -> torch.Tensor | Tuple[torch.Tensor, ...]:
+        inputs, _ = tree_flatten((args, kwargs))
         cudagraphs_enabled = torch_tensorrt.runtime.get_whole_cudagraphs_mode()
         if cudagraphs_enabled:
             shape_changed = self.validate_input_shapes(inputs)
             need_cudagraphs_record = shape_changed or self.is_weight_streaming_set
             if need_cudagraphs_record:
                 if self.cudagraph:
                     self.cudagraph.reset()
-                self._input_buffers = [None] * len(self.inputs)
+                self._input_buffers = [None] * len(inputs)
 
             self.is_weight_streaming_set = False
             # Ensure inputs are available in all scopes and cast symbolic integers to Tensors
@@ -94,10 +130,10 @@ def forward(self, *inputs: torch.Tensor) -> torch.Tensor | Tuple[torch.Tensor, .
                 for i in inputs
             ]
             assert len(contiguous_inputs) == len(
-                self.inputs
-            ), f"Wrong number of inputs, expect {len(self.inputs)} get {len(contiguous_inputs)}."
+                inputs
+            ), f"Wrong number of inputs, expect {len(inputs)} get {len(contiguous_inputs)}."
 
-            for i, _ in enumerate(self.inputs):
+            for i, _ in enumerate(inputs):
                 if not contiguous_inputs[i].is_cuda:
                     logger.warning(
                         f"Detected input[{i}] is not on a cuda device. "
@@ -112,8 +148,8 @@ def forward(self, *inputs: torch.Tensor) -> torch.Tensor | Tuple[torch.Tensor, .
                     )
 
                 assert (
-                    contiguous_inputs[i].dtype == self.inputs[i].dtype
-                ), f"Dtype mismatch for {i}th input. Expect {self.inputs[i].dtype}, got {contiguous_inputs[i].dtype}."
+                    contiguous_inputs[i].dtype == inputs[i].dtype
+                ), f"Dtype mismatch for {i}th input. Expect {inputs[i].dtype}, got {contiguous_inputs[i].dtype}."
 
                 if need_cudagraphs_record:
                     # If cudagraphs is enabled, this memory is reserved for future cudagraph runs
@@ -122,6 +158,13 @@ def forward(self, *inputs: torch.Tensor) -> torch.Tensor | Tuple[torch.Tensor, .
                 else:
                     self._input_buffers[i].copy_(contiguous_inputs[i])
 
+            if need_cudagraphs_record:
+                # Reconstruct the original args and kwargs structure from static input buffers
+                # using the input specification stored during module compilation
+                args, kwargs = tree_unflatten(
+                    self._input_buffers, self.compiled_module._in_spec
+                )
+
             self._caller_stream = torch.cuda.current_stream()
             if (
                 self._engine_stream == torch.cuda.default_stream()
@@ -135,9 +178,7 @@ def forward(self, *inputs: torch.Tensor) -> torch.Tensor | Tuple[torch.Tensor, .
                 if need_cudagraphs_record:
                     self.cudagraph = torch.cuda.CUDAGraph()
                     with torch.cuda.graph(self.cudagraph, stream=self._engine_stream):
-                        self._output_buffers = self.compiled_module(
-                            *self._input_buffers
-                        )
+                        self._output_buffers = self.compiled_module(*args, **kwargs)
 
                 self.cudagraph.replay()  # type: ignore
             self._caller_stream.wait_stream(self._engine_stream)
@@ -154,4 +195,4 @@ def forward(self, *inputs: torch.Tensor) -> torch.Tensor | Tuple[torch.Tensor, .
             if self.cudagraph:
                 self.cudagraph.reset()
                 self.cudagraph = None
-            return self.compiled_module(*inputs)
+            return self.compiled_module(*args, **kwargs)