[MLIR][Python] Use ir.Value directly instead of _SubClassValueT

_SubClassValueT is only useful when it is has >1 usage in a signature.
This was not true for the signatures produced by tblgen.

For example

    def call(result, callee, operands_, *, loc=None, ip=None) -> _SubClassValueT:
      ...

here a type checker does not have enough information to infer a type argument
for _SubClassValueT, and thus effectively treats it as Any.

mlir/python/mlir/_mlir_libs/_mlir/__init__.pyi

@@ -10,4 +10,4 @@ class _Globals:
     def _check_dialect_module_loaded(self, dialect_namespace: str) -> bool: ...
 
 def register_dialect(dialect_class: type) -> object: ...
-def register_operation(dialect_class: type) -> object: ...
+def register_operation(dialect_class: type, *, replace: bool = ...) -> object: ...

mlir/python/mlir/dialects/_ods_common.py

@@ -8,7 +8,6 @@
     Sequence as _Sequence,
     Tuple as _Tuple,
     Type as _Type,
-    TypeVar as _TypeVar,
     Union as _Union,
 )
 
@@ -143,12 +142,6 @@ def get_op_result_or_op_results(
         else op
     )
 
-
-# This is the standard way to indicate subclass/inheritance relationship
-# see the typing.Type doc string.
-_U = _TypeVar("_U", bound=_cext.ir.Value)
-SubClassValueT = _Type[_U]
-
 ResultValueTypeTuple = _cext.ir.Operation, _cext.ir.OpView, _cext.ir.Value
 ResultValueT = _Union[ResultValueTypeTuple]
 VariadicResultValueT = _Union[ResultValueT, _Sequence[ResultValueT]]

mlir/python/mlir/dialects/arith.py

@@ -12,7 +12,6 @@
         get_default_loc_context as _get_default_loc_context,
         _cext as _ods_cext,
         get_op_result_or_op_results as _get_op_result_or_op_results,
-        SubClassValueT as _SubClassValueT,
     )
 
     from typing import Any, List, Union
@@ -81,5 +80,5 @@ def literal_value(self) -> Union[int, float]:
 
 def constant(
     result: Type, value: Union[int, float, Attribute], *, loc=None, ip=None
-) -> _SubClassValueT:
+) -> Value:
     return _get_op_result_or_op_results(ConstantOp(result, value, loc=loc, ip=ip))

mlir/test/mlir-tblgen/op-python-bindings.td

@@ -7,7 +7,6 @@ include "mlir/Interfaces/InferTypeOpInterface.td"
 // CHECK: @_ods_cext.register_dialect
 // CHECK: class _Dialect(_ods_ir.Dialect):
   // CHECK: DIALECT_NAMESPACE = "test"
-  // CHECK: pass
 def Test_Dialect : Dialect {
   let name = "test";
   let cppNamespace = "Test";

mlir/test/python/ir/value.py

@@ -3,7 +3,6 @@
 import gc
 from mlir.ir import *
 from mlir.dialects import func
-from mlir.dialects._ods_common import SubClassValueT
 
 
 def run(f):
@@ -270,7 +269,7 @@ def __str__(self):
             return super().__str__().replace(Value.__name__, NOPBlockArg.__name__)
 
     @register_value_caster(IntegerType.static_typeid)
-    def cast_int(v) -> SubClassValueT:
+    def cast_int(v) -> Value:
         print("in caster", v.__class__.__name__)
         if isinstance(v, OpResult):
             return NOPResult(v)

mlir/tools/mlir-tblgen/OpPythonBindingGen.cpp

@@ -31,7 +31,6 @@ constexpr const char *fileHeader = R"Py(
 
 from ._ods_common import _cext as _ods_cext
 from ._ods_common import (
-    SubClassValueT as _SubClassValueT,
     equally_sized_accessor as _ods_equally_sized_accessor,
     get_default_loc_context as _ods_get_default_loc_context,
     get_op_result_or_op_results as _get_op_result_or_op_results,
@@ -52,8 +51,6 @@ constexpr const char *dialectClassTemplate = R"Py(
 @_ods_cext.register_dialect
 class _Dialect(_ods_ir.Dialect):
   DIALECT_NAMESPACE = "{0}"
-  pass
-
 )Py";
 
 constexpr const char *dialectExtensionTemplate = R"Py(
@@ -1007,14 +1004,13 @@ static void emitValueBuilder(const Operator &op,
       });
   std::string nameWithoutDialect =
       op.getOperationName().substr(op.getOperationName().find('.') + 1);
-  os << llvm::formatv(valueBuilderTemplate, sanitizeName(nameWithoutDialect),
-                      op.getCppClassName(),
-                      llvm::join(valueBuilderParams, ", "),
-                      llvm::join(opBuilderArgs, ", "),
-                      (op.getNumResults() > 1
-                           ? "_Sequence[_SubClassValueT]"
-                           : (op.getNumResults() > 0 ? "_SubClassValueT"
-                                                     : "_ods_ir.Operation")));
+  os << llvm::formatv(
+      valueBuilderTemplate, sanitizeName(nameWithoutDialect),
+      op.getCppClassName(), llvm::join(valueBuilderParams, ", "),
+      llvm::join(opBuilderArgs, ", "),
+      (op.getNumResults() > 1
+           ? "_Sequence[_ods_ir.Value]"
+           : (op.getNumResults() > 0 ? "_ods_ir.Value" : "_ods_ir.Operation")));
 }
 
 /// Emits bindings for a specific Op to the given output stream.