Add string versions of argument funcs in jit Node (#45464)

Summary:
Pull Request resolved: #45464

Usage of Symbols to find arguments requires one to generate a nonsense symbol for inputs which don't already have one. The intention of symbols appears to be something of an internalized string, but the namespace component doesn't apply to an argument. In order to access the arguments by name without adding new symbols, versions of those functions with std::string input was added. These can be proved valid based on the existing codepath. Additionally, a hasNamedInput convenience function was added to remove the necessity of a try/catch block in user code.

The primary motivation is to be able to easily handle the variable number of arguments in glow, so that the arange op may be implemented.

Reviewed By: eellison

Differential Revision: D23972315

fbshipit-source-id: 3e0b41910cf07e916186f1506281fb221725a91b

torch/csrc/jit/ir/ir.cpp

@@ -846,22 +846,40 @@ void Value::replaceAllUsesAfterNodeWith(const Node* node, Value* newValue) {
       uses_.end());
 }
 
-size_t findArgument(const FunctionSchema& the_schema, Symbol name) {
-  auto name_str = name.toUnqualString();
+size_t findArgument(
+    const FunctionSchema& the_schema,
+    const std::string& unqualName) {
   for (size_t i = 0; i < the_schema.arguments().size(); ++i) {
     const Argument* arg = &the_schema.arguments()[i];
-    if (arg->name() == name_str) {
+    if (arg->name() == unqualName) {
       return i;
     }
   }
   throw std::runtime_error(
-      std::string("Couldn't find an argument called ") + name.toQualString());
+      std::string("Couldn't find an argument called ") + unqualName);
+}
+
+size_t findArgument(const FunctionSchema& the_schema, Symbol name) {
+  const auto unqualName = name.toUnqualString();
+  return findArgument(the_schema, unqualName);
 }
 
 c10::optional<IValue> Node::get(Symbol name) const {
   return toIValue(namedInput(name));
 }
 
+bool Node::hasNamedInput(const std::string& name) const {
+  for (const auto& argument : schema().arguments()) {
+    if (argument.name() == name) {
+      return true;
+    }
+  }
+  return false;
+}
+
+Value* Node::namedInput(const std::string& unqualName) const {
+  return input(findArgument(schema(), unqualName));
+}
 Value* Node::namedInput(Symbol name) const {
   return input(findArgument(schema(), name));
 }

torch/csrc/jit/ir/ir.h

@@ -414,6 +414,8 @@ struct TORCH_API Node {
     return inputs_.at(i);
   }
 
+  bool hasNamedInput(const std::string& unqualName) const;
+  Value* namedInput(const std::string& unqualName) const;
   Value* namedInput(Symbol name) const;
 
   c10::optional<IValue> get(Symbol name) const;