Fix loop body value creation (#2777)

Create and use ir.Value in loop subgraph inputs and bodies to avoid
unintentional duplication of ir.Values (which led to invalid IR graphs).

---------

Signed-off-by: Justin Chu <justinchuby@users.noreply.github.com>

Author: justinchuby

onnxscript/_internal/converter.py

@@ -1206,7 +1206,11 @@ def _translate_loop_stmt(self, loop_stmt: ast.For | ast.While) -> None:
                 self.fail(loop_stmt, "Unsupported loop bound, it should be 'range(?)'.")
             assert not iter.keywords, "Unsupported loop bound."
             o_loop_bound = self._translate_expr(iter.args[0], "loop_bound")
-            onnx_cond_var = ir.Value(name=self.generate_unique_name("cond_in"))  # TODO(Rama)
+            onnx_cond_var = make_value(
+                self.generate_unique_name("cond_in"),
+                onnx_types.BOOL,
+                self._source_of(loop_stmt),
+            )
             i_cond_var = onnx_cond_var
             cond_while = None
             o_loop_condition = None  # No condition for a for loop.
@@ -1220,8 +1224,12 @@ def _translate_loop_stmt(self, loop_stmt: ast.For | ast.While) -> None:
                 )
             python_loop_var_name = "infinite_loop"
             o_loop_bound = None
-            i_cond_var = ir.Value(name=test.id)  # TODO(Rama)
-            cond_while = ir.Value(name=test.id)  # TODO(Rama)
+            i_cond_var = make_value(
+                self.generate_unique_name(test.id),
+                onnx_types.BOOL,
+                self._source_of(loop_stmt),
+            )
+            cond_while = test.id
             onnx_cond_var = None
             o_loop_condition = self._translate_name_expr(test)
             # we need to go through all the instructions to see
@@ -1254,20 +1262,11 @@ def _translate_loop_stmt(self, loop_stmt: ast.For | ast.While) -> None:
             values.SymbolValue(onnx_loop_var, self._source_of(loop_stmt)),
         )
 
-        self._current_fn.append_parameter(
-            make_value(
-                i_cond_var.name,
-                onnx_types.BOOL,
-                self._source_of(loop_stmt),
-            )
-        )
+        self._current_fn.append_parameter(i_cond_var)
 
         for pv in loop_state_vars:
             onnx_var_name = self.generate_unique_name(pv)
-            # TODO: retrieve the annotation for variable pv is any is specified.
-            # typeinfo = self._eval_constant_expr(pv.annotation)
-            typeinfo = None
-            parameter = make_value(onnx_var_name, typeinfo, self._source_of(loop_stmt))
+            parameter = make_value(onnx_var_name, None, self._source_of(loop_stmt))
             self._current_fn.append_parameter(parameter)
             self._bind(
                 pv,
@@ -1306,33 +1305,25 @@ def _translate_loop_stmt(self, loop_stmt: ast.For | ast.While) -> None:
                 continue
             self._translate_stmt(s)
 
-        onnx_cond_out_name = self.generate_unique_name("cond_out")
-
         if cond_while is not None:
             # Loop while
             current_scope = self._current_scope()
-            if cond_while.name not in current_scope:
+            if cond_while not in current_scope:
                 self.fail(
                     loop_stmt,
-                    f"Unable to find condition variable {cond_while.name} in known "
+                    f"Unable to find condition variable {cond_while} in known "
                     f"variables {list(current_scope)!r}.",
                 )
-            onnx_cond_var = current_scope[cond_while.name].value
+            onnx_cond_var = current_scope[cond_while].value
 
-        self.emit(
-            [onnx_cond_out_name],
+        cond_out = self.emit1(
+            [self.generate_unique_name("cond_out")],
             values.Op(self.default_opset, operator_name),
             [condition_name or onnx_cond_var],
             [],
         )
+        self._current_fn.outputs.append(cond_out)
 
-        self._current_fn.outputs.append(
-            make_value(
-                onnx_cond_out_name,
-                onnx_types.BOOL,
-                self._source_of(loop_stmt),
-            )
-        )
         for pv in loop_state_vars:
             onnx_var = self._py_var_to_onnx_var(pv, self._source_of(loop_stmt))
             if onnx_var.name not in self._current_fn.assigned_names:
@@ -1342,11 +1333,7 @@ def _translate_loop_stmt(self, loop_stmt: ast.For | ast.While) -> None:
                 # In this case, we create a copy of y, treating the statement as
                 # shorthand for "x = op.Identity(y)".
                 onnx_var = self._emit_copy(onnx_var, pv)
-            # TODO: retrieve variable type for the annotation if any.
-            typeinfo = None
-            self._current_fn.outputs.append(
-                make_value(onnx_var.name, typeinfo, self._source_of(loop_stmt))
-            )
+            self._current_fn.outputs.append(onnx_var)
         body = self._exit_scope()
         inputs = [o_loop_bound, o_loop_condition] + [
             self._py_var_to_onnx_var(pv, self._source_of(loop_stmt)) for pv in loop_state_vars