feat(//core/conversion): Adding a check to detect programs that will

result in empty engines and error out

Signed-off-by: Naren Dasan <[email protected]>
Signed-off-by: Naren Dasan <[email protected]>

Author: narendasan

Diff for: core/conversion/conversion.cpp

@@ -433,6 +433,30 @@ std::set<std::string> GetUnsupportedOpsInBlock(const torch::jit::Block* b) {
   return unsupported_ops;
 }
 
+std::set<std::string> ConvertableOpsInBlock(const torch::jit::Block* b) {
+  std::set<std::string> convertable_ops;
+  for (const auto n : b->nodes()) {
+    if (n->kind() == torch::jit::prim::Loop || n->kind() == torch::jit::prim::If || converters::node_is_convertable(n)) {
+      if (n->blocks().size() > 0) {
+        for (const auto sub_b : n->blocks()) {
+          auto sub_b_convertable_ops = ConvertableOpsInBlock(sub_b);
+          convertable_ops.insert(sub_b_convertable_ops.begin(), sub_b_convertable_ops.end());
+        }
+      }
+      if (converters::node_is_convertable(n)) {
+        auto schema = n->maybeSchema();
+        TRTORCH_CHECK(
+            schema,
+            "Unable to get schema for Node " << util::node_info(n) << " (conversion.CheckForConvertableOps)");
+        std::stringstream ss;
+        ss << *schema;
+        convertable_ops.insert(ss.str());
+      }
+    }
+  }
+  return convertable_ops;
+}
+
 bool VerifyConverterSupportForBlock(const torch::jit::Block* b) {
   auto unsupported_ops = GetUnsupportedOpsInBlock(b);
 
@@ -448,7 +472,19 @@ bool VerifyConverterSupportForBlock(const torch::jit::Block* b) {
     unsupported_msg << "https://www.github.com/nvidia/TRTorch/issues" << std::endl;
     LOG_ERROR(unsupported_msg.str());
     return false;
-  } else {
+  }
+
+  if (ConvertableOpsInBlock(b).size() == 0) {
+    std::stringstream unsupported_msg;
+    unsupported_msg << "Method requested cannot be compiled by TRTorch.\nThere is no work to be done since the resulting compiled program will contain an engine that is empty."
+                    << std::endl;
+    unsupported_msg << "This may be because there are no operators that can be added to the TensorRT graph or all operators have a resolved compile time value."
+                    << std::endl;
+    LOG_ERROR(unsupported_msg.str());
+    return false;
+  }
+
+  else {
     return true;
   }
 }