[VM] Add get_input_index support.

python/tvm/runtime/vm.py

@@ -345,6 +345,7 @@ def __init__(self, exe, device, memory_cfg=None):
         self._invoke_stateful = self.module["invoke_stateful"]
         self._get_output = self.module["get_output"]
         self._get_num_outputs = self.module["get_num_outputs"]
+        self._get_input_index = self.module["get_input_index"]
         self._set_input = self.module["set_input"]
         self._setup_device(device, memory_cfg)
 
@@ -490,3 +491,19 @@ def get_outputs(self):
         outputs : List[NDArray]
         """
         return [self._get_output(i) for i in range(self._get_num_outputs())]
+
+    def get_input_index(self, input_name, func_name="main"):
+        """Get inputs index via input name.
+        Parameters
+        ----------
+        name : str
+          The input key name
+        func_name : str
+          The function name
+
+        Returns
+        -------
+        index: int
+          The input index. -1 will be returned if the given input name is not found.
+        """
+        return self._get_input_index(input_name, func_name)

src/runtime/vm/vm.cc

@@ -159,6 +159,21 @@ PackedFunc VirtualMachine::GetFunction(const std::string& name,
         return 1;
       }
     });
+  } else if (name == "get_input_index") {
+    return TypedPackedFunc<int64_t(std::string, std::string)>(
+        [this](std::string input_name, std::string func_name) {
+          auto gvit = exec_->global_map.find(func_name);
+          ICHECK(gvit != exec_->global_map.end()) << "Cannot find function " << func_name;
+          auto func_index = gvit->second;
+          const auto& vm_func = exec_->functions[func_index];
+          const auto& param_names = vm_func.params;
+          for (uint64_t i = 0; i < param_names.size(); i++) {
+            if (input_name == param_names[i]) {
+              return static_cast<int64_t>(i);
+            }
+          }
+          return static_cast<int64_t>(-1);
+        });
   } else if (name == "init") {
     return PackedFunc([sptr_to_self, this](TVMArgs args, TVMRetValue* rv) {
       ICHECK_EQ(args.size() % 3, 0);

tests/python/relay/test_vm.py

@@ -941,5 +941,22 @@ def test_get_output_multiple():
     np.testing.assert_allclose(outputs[1].numpy(), inp)
 
 
+def test_get_input_index():
+    target = tvm.target.Target("llvm")
+
+    # Build a IRModule.
+    data_0, data_1 = ["d1", "d2"]
+    x, y = [relay.var(c, shape=(10,)) for c in [data_0, data_1]]
+    f = relay.Function([x, y], x + y)
+    mod = IRModule.from_expr(f)
+
+    # Compile to VMExecutable.
+    vm_exec = vm.compile(mod, target=target)
+    vm_factory = runtime.vm.VirtualMachine(vm_exec, tvm.cpu())
+    assert vm_factory.get_input_index(data_1) == 1
+    assert vm_factory.get_input_index(data_0) == 0
+    assert vm_factory.get_input_index("invalid") == -1
+
+
 if __name__ == "__main__":
     pytest.main([__file__])