[mlir][python] loading dialect module is best effort only

Author: makslevental

mlir/lib/Bindings/Python/IRModule.cpp

@@ -132,10 +132,8 @@ PyGlobals::lookupAttributeBuilder(const std::string &attributeKind) {
 
 std::optional<py::function> PyGlobals::lookupTypeCaster(MlirTypeID mlirTypeID,
                                                         MlirDialect dialect) {
-  // Make sure dialect module is loaded.
-  if (!loadDialectModule(unwrap(mlirDialectGetNamespace(dialect))))
-    return std::nullopt;
-
+  // Try to load dialect module.
+  (void)loadDialectModule(unwrap(mlirDialectGetNamespace(dialect)));
   const auto foundIt = typeCasterMap.find(mlirTypeID);
   if (foundIt != typeCasterMap.end()) {
     assert(foundIt->second && "type caster is defined");
@@ -146,7 +144,8 @@ std::optional<py::function> PyGlobals::lookupTypeCaster(MlirTypeID mlirTypeID,
 
 std::optional<py::function> PyGlobals::lookupValueCaster(MlirTypeID mlirTypeID,
                                                          MlirDialect dialect) {
-  loadDialectModule(unwrap(mlirDialectGetNamespace(dialect)));
+  // Try to load dialect module.
+  (void)loadDialectModule(unwrap(mlirDialectGetNamespace(dialect)));
   const auto foundIt = valueCasterMap.find(mlirTypeID);
   if (foundIt != valueCasterMap.end()) {
     assert(foundIt->second && "value caster is defined");

mlir/python/CMakeLists.txt

@@ -44,17 +44,6 @@ declare_mlir_python_sources(MLIRPythonCAPI.HeaderSources
   SOURCES_GLOB "mlir-c/*.h"
 )
 
-# The builtin dialect is special (e.g., type casters and such expect it to be loaded
-# in order to work) so we add it to Core instead of Dialects so that anyone depending on
-# Core will get it automatically.
-declare_mlir_dialect_python_bindings(
-  ADD_TO_PARENT MLIRPythonSources.Core
-  ROOT_DIR "${CMAKE_CURRENT_SOURCE_DIR}/mlir"
-  TD_FILE dialects/BuiltinOps.td
-  SOURCES
-    dialects/builtin.py
-  DIALECT_NAME builtin)
-
 ################################################################################
 # Dialect bindings
 ################################################################################
@@ -95,6 +84,14 @@ declare_mlir_dialect_python_bindings(
     "../../include/mlir/Dialect/Bufferization/IR/BufferizationEnums.td"
 )
 
+declare_mlir_dialect_python_bindings(
+  ADD_TO_PARENT MLIRPythonSources.Dialects
+  ROOT_DIR "${CMAKE_CURRENT_SOURCE_DIR}/mlir"
+  TD_FILE dialects/BuiltinOps.td
+  SOURCES
+    dialects/builtin.py
+  DIALECT_NAME builtin)
+
 declare_mlir_dialect_python_bindings(
   ADD_TO_PARENT MLIRPythonSources.Dialects
   ROOT_DIR "${CMAKE_CURRENT_SOURCE_DIR}/mlir"