Add TensorRT Support

- This change introduces support for enabling the TensorRT execution
   backend. It is configured in basically the same manner as the CUDA
   backend, with analogous APIs.

 - Added a unit test and benchmark for the TensorRT backend. To try it,
   run "go test -v -bench=." on a system where TensorRT is installed,
   and you're using a build of onnxruntime with TensorRT enabled.

onnxruntime_test.go

@@ -812,3 +812,87 @@ func BenchmarkCUDASession(b *testing.B) {
 		}
 	}
 }
+
+// Creates a SessionOptions struct that's configured to enable TensorRT.
+// Basically the same as getCUDASessionOptions; see the comments there.
+func getTensorRTSessionOptions(t testing.TB) *SessionOptions {
+	trtOptions, e := NewTensorRTProviderOptions()
+	if e != nil {
+		t.Skipf("Error creating TensorRT provider options; %s. "+
+			"Your version of the onnxruntime library may not include "+
+			"TensorRT support. Skipping the remainder of this test.\n", e)
+	}
+	defer trtOptions.Destroy()
+	// Arbitrarily update an option to test trtOptions.Update()
+	e = trtOptions.Update(
+		map[string]string{"trt_max_partition_iterations": "60"})
+	if e != nil {
+		t.Skipf("Error updating TensorRT options: %s. Your system may not "+
+			"support TensorRT, TensorRT may be misconfigured, or it may be "+
+			"incompatible with this build of onnxruntime. Skipping the "+
+			"remainder of this test.\n", e)
+	}
+	sessionOptions, e := NewSessionOptions()
+	if e != nil {
+		t.Logf("Error creating SessionOptions: %s\n", e)
+		t.FailNow()
+	}
+	e = sessionOptions.AppendExecutionProviderTensorRT(trtOptions)
+	if e != nil {
+		t.Logf("Error setting TensorRT execution provider: %s\n", e)
+		t.FailNow()
+	}
+	return sessionOptions
+}
+
+func TestTensorRTSession(t *testing.T) {
+	InitializeRuntime(t)
+	defer CleanupRuntime(t)
+	sessionOptions := getTensorRTSessionOptions(t)
+	defer sessionOptions.Destroy()
+
+	input, output := prepareBenchmarkTensors(t, 1337)
+	defer input.Destroy()
+	defer output.Destroy()
+	session, e := NewAdvancedSession("test_data/example_big_compute.onnx",
+		[]string{"Input"}, []string{"Output"}, []ArbitraryTensor{input},
+		[]ArbitraryTensor{output}, sessionOptions)
+	if e != nil {
+		t.Logf("Error creating session: %s\n", e)
+		t.FailNow()
+	}
+	defer session.Destroy()
+	e = session.Run()
+	if e != nil {
+		t.Logf("Error running session with TensorRT: %s\n", e)
+		t.FailNow()
+	}
+	t.Logf("Ran session with TensorRT OK.\n")
+}
+
+func BenchmarkTensorRTSession(b *testing.B) {
+	b.StopTimer()
+	InitializeRuntime(b)
+	defer CleanupRuntime(b)
+	sessionOptions := getTensorRTSessionOptions(b)
+	defer sessionOptions.Destroy()
+	input, output := prepareBenchmarkTensors(b, benchmarkRNGSeed)
+	defer input.Destroy()
+	defer output.Destroy()
+	session, e := NewAdvancedSession("test_data/example_big_compute.onnx",
+		[]string{"Input"}, []string{"Output"}, []ArbitraryTensor{input},
+		[]ArbitraryTensor{output}, sessionOptions)
+	if e != nil {
+		b.Logf("Error creating session: %s\n", e)
+		b.FailNow()
+	}
+	defer session.Destroy()
+	b.StartTimer()
+	for n := 0; n < b.N; n++ {
+		e = session.Run()
+		if e != nil {
+			b.Logf("Error running iteration %d/%d: %s\n", n+1, b.N, e)
+			b.FailNow()
+		}
+	}
+}