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[mlir][python] Cache import of ir module in type casters. #160000

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Merged
merged 1 commit into from
Sep 24, 2025
+71 −29
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[mlir][python] Cache import of ir module in type casters. #160000

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100 changes: 71 additions & 29 deletions mlir/include/mlir/Bindings/Python/NanobindAdaptors.h
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,9 @@
#ifndef MLIR_BINDINGS_PYTHON_NANOBINDADAPTORS_H
#define MLIR_BINDINGS_PYTHON_NANOBINDADAPTORS_H

#include <atomic>
#include <cstdint>
#include <memory>
#include <optional>

#include "mlir-c/Diagnostics.h"
Expand All @@ -30,6 +32,57 @@
// clang-format on
#include "llvm/ADT/Twine.h"

namespace mlir {
namespace python {
namespace {

// Safely calls Python initialization code on first use, avoiding deadlocks.
template <typename T>
class SafeInit {
public:
typedef std::unique_ptr<T> (*F)();

explicit SafeInit(F init_fn) : initFn(init_fn) {}

T &get() {
if (T *result = output.load()) {
return *result;
}

// Note: init_fn() may be called multiple times if, for example, the GIL is
// released during its execution. The intended use case is for module
// imports which are safe to perform multiple times. We are careful not to
// hold a lock across init_fn() to avoid lock ordering problems.
std::unique_ptr<T> m = initFn();
{
nanobind::ft_lock_guard lock(mu);
if (T *result = output.load()) {
return *result;
}
T *p = m.release();
output.store(p);
return *p;
}
}

private:
nanobind::ft_mutex mu;
std::atomic<T *> output{nullptr};
F initFn;
};

nanobind::module_ &irModule() {
static SafeInit<nanobind::module_> init([]() {
return std::make_unique<nanobind::module_>(
nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir")));
});
return init.get();
}

} // namespace
} // namespace python
} // namespace mlir

// Raw CAPI type casters need to be declared before use, so always include them
// first.
namespace nanobind {
Expand Down Expand Up @@ -75,7 +128,7 @@ struct type_caster<MlirAffineMap> {
cleanup_list *cleanup) noexcept {
nanobind::object capsule =
nanobind::steal<nanobind::object>(mlirPythonAffineMapToCapsule(v));
return nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
return mlir::python::irModule()
.attr("AffineMap")
.attr(MLIR_PYTHON_CAPI_FACTORY_ATTR)(capsule)
.release();
Expand All @@ -97,7 +150,7 @@ struct type_caster<MlirAttribute> {
cleanup_list *cleanup) noexcept {
nanobind::object capsule =
nanobind::steal<nanobind::object>(mlirPythonAttributeToCapsule(v));
return nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
return mlir::python::irModule()
.attr("Attribute")
.attr(MLIR_PYTHON_CAPI_FACTORY_ATTR)(capsule)
.attr(MLIR_PYTHON_MAYBE_DOWNCAST_ATTR)()
Expand Down Expand Up @@ -128,9 +181,7 @@ struct type_caster<MlirContext> {
// TODO: This raises an error of "No current context" currently.
// Update the implementation to pretty-print the helpful error that the
// core implementations print in this case.
src = nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
.attr("Context")
.attr("current");
src = mlir::python::irModule().attr("Context").attr("current");
}
std::optional<nanobind::object> capsule = mlirApiObjectToCapsule(src);
value = mlirPythonCapsuleToContext(capsule->ptr());
Expand All @@ -153,7 +204,7 @@ struct type_caster<MlirDialectRegistry> {
cleanup_list *cleanup) noexcept {
nanobind::object capsule = nanobind::steal<nanobind::object>(
mlirPythonDialectRegistryToCapsule(v));
return nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
return mlir::python::irModule()
.attr("DialectRegistry")
.attr(MLIR_PYTHON_CAPI_FACTORY_ATTR)(capsule)
.release();
Expand All @@ -167,9 +218,7 @@ struct type_caster<MlirLocation> {
bool from_python(handle src, uint8_t flags, cleanup_list *cleanup) noexcept {
if (src.is_none()) {
// Gets the current thread-bound context.
src = nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
.attr("Location")
.attr("current");
src = mlir::python::irModule().attr("Location").attr("current");
}
if (auto capsule = mlirApiObjectToCapsule(src)) {
value = mlirPythonCapsuleToLocation(capsule->ptr());
Expand All @@ -181,7 +230,7 @@ struct type_caster<MlirLocation> {
cleanup_list *cleanup) noexcept {
nanobind::object capsule =
nanobind::steal<nanobind::object>(mlirPythonLocationToCapsule(v));
return nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
return mlir::python::irModule()
.attr("Location")
.attr(MLIR_PYTHON_CAPI_FACTORY_ATTR)(capsule)
.release();
Expand All @@ -203,7 +252,7 @@ struct type_caster<MlirModule> {
cleanup_list *cleanup) noexcept {
nanobind::object capsule =
nanobind::steal<nanobind::object>(mlirPythonModuleToCapsule(v));
return nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
return mlir::python::irModule()
.attr("Module")
.attr(MLIR_PYTHON_CAPI_FACTORY_ATTR)(capsule)
.release();
Expand Down Expand Up @@ -250,7 +299,7 @@ struct type_caster<MlirOperation> {
return nanobind::none();
nanobind::object capsule =
nanobind::steal<nanobind::object>(mlirPythonOperationToCapsule(v));
return nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
return mlir::python::irModule()
.attr("Operation")
.attr(MLIR_PYTHON_CAPI_FACTORY_ATTR)(capsule)
.release();
Expand All @@ -274,7 +323,7 @@ struct type_caster<MlirValue> {
return nanobind::none();
nanobind::object capsule =
nanobind::steal<nanobind::object>(mlirPythonValueToCapsule(v));
return nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
return mlir::python::irModule()
.attr("Value")
.attr(MLIR_PYTHON_CAPI_FACTORY_ATTR)(capsule)
.attr(MLIR_PYTHON_MAYBE_DOWNCAST_ATTR)()
Expand Down Expand Up @@ -312,7 +361,7 @@ struct type_caster<MlirTypeID> {
return nanobind::none();
nanobind::object capsule =
nanobind::steal<nanobind::object>(mlirPythonTypeIDToCapsule(v));
return nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
return mlir::python::irModule()
.attr("TypeID")
.attr(MLIR_PYTHON_CAPI_FACTORY_ATTR)(capsule)
.release();
Expand All @@ -334,7 +383,7 @@ struct type_caster<MlirType> {
cleanup_list *cleanup) noexcept {
nanobind::object capsule =
nanobind::steal<nanobind::object>(mlirPythonTypeToCapsule(t));
return nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
return mlir::python::irModule()
.attr("Type")
.attr(MLIR_PYTHON_CAPI_FACTORY_ATTR)(capsule)
.attr(MLIR_PYTHON_MAYBE_DOWNCAST_ATTR)()
Expand Down Expand Up @@ -453,11 +502,9 @@ class mlir_attribute_subclass : public pure_subclass {
mlir_attribute_subclass(nanobind::handle scope, const char *attrClassName,
IsAFunctionTy isaFunction,
GetTypeIDFunctionTy getTypeIDFunction = nullptr)
: mlir_attribute_subclass(
scope, attrClassName, isaFunction,
nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
.attr("Attribute"),
getTypeIDFunction) {}
: mlir_attribute_subclass(scope, attrClassName, isaFunction,
irModule().attr("Attribute"),
getTypeIDFunction) {}

/// Subclasses with a provided mlir.ir.Attribute super-class. This must
/// be used if the subclass is being defined in the same extension module
Expand Down Expand Up @@ -540,11 +587,8 @@ class mlir_type_subclass : public pure_subclass {
mlir_type_subclass(nanobind::handle scope, const char *typeClassName,
IsAFunctionTy isaFunction,
GetTypeIDFunctionTy getTypeIDFunction = nullptr)
: mlir_type_subclass(
scope, typeClassName, isaFunction,
nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
.attr("Type"),
getTypeIDFunction) {}
: mlir_type_subclass(scope, typeClassName, isaFunction,
irModule().attr("Type"), getTypeIDFunction) {}

/// Subclasses with a provided mlir.ir.Type super-class. This must
/// be used if the subclass is being defined in the same extension module
Expand Down Expand Up @@ -631,10 +675,8 @@ class mlir_value_subclass : public pure_subclass {
/// Subclasses by looking up the super-class dynamically.
mlir_value_subclass(nanobind::handle scope, const char *valueClassName,
IsAFunctionTy isaFunction)
: mlir_value_subclass(
scope, valueClassName, isaFunction,
nanobind::module_::import_(MAKE_MLIR_PYTHON_QUALNAME("ir"))
.attr("Value")) {}
: mlir_value_subclass(scope, valueClassName, isaFunction,
irModule().attr("Value")) {}

/// Subclasses with a provided mlir.ir.Value super-class. This must
/// be used if the subclass is being defined in the same extension module
Expand Down