Trt compiler fixes (Project-MONAI#8064)

Fixes Project-MONAI#8061.

### Description

Post-merge fixes for trt_compile()

### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [ ] Breaking change (fix or new feature that would cause existing
functionality to change).
- [ ] New tests added to cover the changes.
- [ ] Integration tests passed locally by running `./runtests.sh -f -u
--net --coverage`.
- [ ] Quick tests passed locally by running `./runtests.sh --quick
--unittests --disttests`.
- [ ] In-line docstrings updated.
- [ ] Documentation updated, tested `make html` command in the `docs/`
folder.

---------

Signed-off-by: Boris Fomitchev <bfomitchev@nvidia.com>
Signed-off-by: Yiheng Wang <vennw@nvidia.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: YunLiu <55491388+KumoLiu@users.noreply.github.com>
Co-authored-by: Yiheng Wang <68361391+yiheng-wang-nv@users.noreply.github.com>
Co-authored-by: Yiheng Wang <vennw@nvidia.com>
Co-authored-by: binliunls <107988372+binliunls@users.noreply.github.com>

monai/networks/trt_compiler.py

@@ -342,6 +342,7 @@ def forward(self, model, argv, kwargs):
                     self._build_and_save(model, build_args)
                     # This will reassign input_names from the engine
                     self._load_engine()
+                    assert self.engine is not None
             except Exception as e:
                 if self.fallback:
                     self.logger.info(f"Failed to build engine: {e}")
@@ -403,8 +404,10 @@ def _onnx_to_trt(self, onnx_path):
 
         build_args = self.build_args.copy()
         build_args["tf32"] = self.precision != "fp32"
-        build_args["fp16"] = self.precision == "fp16"
-        build_args["bf16"] = self.precision == "bf16"
+        if self.precision == "fp16":
+            build_args["fp16"] = True
+        elif self.precision == "bf16":
+            build_args["bf16"] = True
 
         self.logger.info(f"Building TensorRT engine for {onnx_path}: {self.plan_path}")
         network = network_from_onnx_path(onnx_path, flags=[trt.OnnxParserFlag.NATIVE_INSTANCENORM])
@@ -502,6 +505,7 @@ def trt_compile(
 ) -> torch.nn.Module:
     """
     Instruments model or submodule(s) with TrtCompiler and replaces its forward() with TRT hook.
+    Note: TRT 10.3 is recommended for best performance. Some nets may even fail to work with TRT 8.x
     Args:
       model: module to patch with TrtCompiler object.
       base_path: TRT plan(s) saved to f"{base_path}[.{submodule}].plan" path.

tests/test_trt_compile.py

@@ -20,10 +20,10 @@
 from monai.handlers import TrtHandler
 from monai.networks import trt_compile
 from monai.networks.nets import UNet, cell_sam_wrapper, vista3d132
-from monai.utils import optional_import
+from monai.utils import min_version, optional_import
 from tests.utils import skip_if_no_cuda, skip_if_quick, skip_if_windows
 
-trt, trt_imported = optional_import("tensorrt")
+trt, trt_imported = optional_import("tensorrt", "10.1.0", min_version)
 polygraphy, polygraphy_imported = optional_import("polygraphy")
 build_sam_vit_b, has_sam = optional_import("segment_anything.build_sam", name="build_sam_vit_b")