Revert "[mlir][python] Make the Context/Operation capsule creation methods work as documented. (#76010)"

ftynse · ftynse · commit 78bd124649ec · 2023-12-21T10:06:44.000Z
This reverts commit bbc2976. This change seems to be at odds with the non-owning part semantics of MlirOperation in C API. Since downstream clients can only take and return MlirOperation, it does not sound correct to force all returns of MlirOperation transfer ownership. Specifically, this makes it impossible for downstreams to implement IR-traversing functions that, e.g., look at neighbors of an operation. The following patch triggers the exception, and there does not seem to be an alternative way for a downstream binding writer to express this: ``` diff --git a/mlir/lib/Bindings/Python/IRCore.cpp b/mlir/lib/Bindings/Python/IRCore.cpp index 39757df..2ce640674245 100644 --- a/mlir/lib/Bindings/Python/IRCore.cpp +++ b/mlir/lib/Bindings/Python/IRCore.cpp @@ -3071,6 +3071,11 @@ void mlir::python::populateIRCore(py::module &m) { py::arg("successors") = py::none(), py::arg("regions") = 0, py::arg("loc") = py::none(), py::arg("ip") = py::none(), py::arg("infer_type") = false, kOperationCreateDocstring) + .def("_get_first_in_block", [](PyOperation &self) -> MlirOperation { + MlirBlock block = mlirOperationGetBlock(self.get()); + MlirOperation first = mlirBlockGetFirstOperation(block); + return first; + }) .def_static( "parse", [](const std::string &sourceStr, const std::string &sourceName, diff --git a/mlir/test/python/ir/operation.py b/mlir/test/python/ir/operation.py index f59b1a2..6b12b8da5c24 100644 --- a/mlir/test/python/ir/operation.py +++ b/mlir/test/python/ir/operation.py @@ -24,6 +24,25 @@ def expect_index_error(callback): except IndexError: pass +@run +def testCustomBind(): + ctx = Context() + ctx.allow_unregistered_dialects = True + module = Module.parse( + r""" + func.func @F1(%arg0: i32) -> i32 { + %1 = "custom.addi"(%arg0, %arg0) : (i32, i32) -> i32 + return %1 : i32 + } + """, + ctx, + ) + add = module.body.operations[0].regions[0].blocks[0].operations[0] + op = add.operation + # This will get a reference to itself. + f1 = op._get_first_in_block() + + # Verify iterator based traversal of the op/region/block hierarchy. # CHECK-LABEL: TEST: testTraverseOpRegionBlockIterators ```
diff --git a/mlir/lib/Bindings/Python/IRCore.cpp b/mlir/lib/Bindings/Python/IRCore.cpp
@@ -602,7 +602,7 @@ py::object PyMlirContext::createFromCapsule(py::object capsule) {
   MlirContext rawContext = mlirPythonCapsuleToContext(capsule.ptr());
   if (mlirContextIsNull(rawContext))
     throw py::error_already_set();
-  return stealExternalContext(rawContext).releaseObject();
+  return forContext(rawContext).releaseObject();
 }
 
 PyMlirContext *PyMlirContext::createNewContextForInit() {
@@ -615,35 +615,18 @@ PyMlirContextRef PyMlirContext::forContext(MlirContext context) {
   auto &liveContexts = getLiveContexts();
   auto it = liveContexts.find(context.ptr);
   if (it == liveContexts.end()) {
-    throw std::runtime_error(
-        "Cannot use a context that is not owned by the Python bindings.");
+    // Create.
+    PyMlirContext *unownedContextWrapper = new PyMlirContext(context);
+    py::object pyRef = py::cast(unownedContextWrapper);
+    assert(pyRef && "cast to py::object failed");
+    liveContexts[context.ptr] = unownedContextWrapper;
+    return PyMlirContextRef(unownedContextWrapper, std::move(pyRef));
   }
-
   // Use existing.
   py::object pyRef = py::cast(it->second);
   return PyMlirContextRef(it->second, std::move(pyRef));
 }
 
-PyMlirContextRef PyMlirContext::stealExternalContext(MlirContext context) {
-  py::gil_scoped_acquire acquire;
-  auto &liveContexts = getLiveContexts();
-  auto it = liveContexts.find(context.ptr);
-  if (it != liveContexts.end()) {
-    throw std::runtime_error(
-        "Cannot transfer ownership of the context to Python "
-        "as it is already owned by Python.");
-  }
-
-  PyMlirContext *unownedContextWrapper = new PyMlirContext(context);
-  // Note that the default return value policy on cast is automatic_reference,
-  // which does not take ownership (delete will not be called).
-  // Just be explicit.
-  py::object pyRef =
-      py::cast(unownedContextWrapper, py::return_value_policy::take_ownership);
-  assert(pyRef && "cast to py::object failed");
-  return PyMlirContextRef(unownedContextWrapper, std::move(pyRef));
-}
-
 PyMlirContext::LiveContextMap &PyMlirContext::getLiveContexts() {
   static LiveContextMap liveContexts;
   return liveContexts;
@@ -1162,18 +1145,6 @@ PyOperationRef PyOperation::forOperation(PyMlirContextRef contextRef,
   return PyOperationRef(existing, std::move(pyRef));
 }
 
-PyOperationRef PyOperation::stealExternalOperation(PyMlirContextRef contextRef,
-                                                   MlirOperation operation) {
-  auto &liveOperations = contextRef->liveOperations;
-  auto it = liveOperations.find(operation.ptr);
-  if (it != liveOperations.end()) {
-    throw std::runtime_error(
-        "Cannot transfer ownership of the operation to Python "
-        "as it is already owned by Python.");
-  }
-  return createInstance(std::move(contextRef), operation, py::none());
-}
-
 PyOperationRef PyOperation::createDetached(PyMlirContextRef contextRef,
                                            MlirOperation operation,
                                            py::object parentKeepAlive) {
@@ -1345,8 +1316,7 @@ py::object PyOperation::createFromCapsule(py::object capsule) {
   if (mlirOperationIsNull(rawOperation))
     throw py::error_already_set();
   MlirContext rawCtxt = mlirOperationGetContext(rawOperation);
-  return stealExternalOperation(PyMlirContext::forContext(rawCtxt),
-                                rawOperation)
+  return forOperation(PyMlirContext::forContext(rawCtxt), rawOperation)
       .releaseObject();
 }
 
@@ -2578,16 +2548,6 @@ void mlir::python::populateIRCore(py::module &m) {
       .def("_get_live_operation_count", &PyMlirContext::getLiveOperationCount)
       .def("_clear_live_operations", &PyMlirContext::clearLiveOperations)
       .def("_get_live_module_count", &PyMlirContext::getLiveModuleCount)
-      .def_static("_testing_create_raw_context_capsule",
-                  []() {
-                    // Creates an MlirContext not known to the Python bindings
-                    // and puts it in a capsule. Used to test interop. Using
-                    // this without passing it back to the capsule creation
-                    // API will leak.
-                    return py::reinterpret_steal<py::object>(
-                        mlirPythonContextToCapsule(
-                            mlirContextCreateWithThreading(false)));
-                  })
       .def_property_readonly(MLIR_PYTHON_CAPI_PTR_ATTR,
                              &PyMlirContext::getCapsule)
       .def(MLIR_PYTHON_CAPI_FACTORY_ATTR, &PyMlirContext::createFromCapsule)
@@ -3013,7 +2973,8 @@ void mlir::python::populateIRCore(py::module &m) {
            py::arg("binary") = false, kOperationPrintStateDocstring)
       .def("print",
            py::overload_cast<std::optional<int64_t>, bool, bool, bool, bool,
-                             bool, py::object, bool>(&PyOperationBase::print),
+                             bool, py::object, bool>(
+               &PyOperationBase::print),
            // Careful: Lots of arguments must match up with print method.
            py::arg("large_elements_limit") = py::none(),
            py::arg("enable_debug_info") = false,
@@ -3085,25 +3046,6 @@ void mlir::python::populateIRCore(py::module &m) {
       .def_property_readonly(MLIR_PYTHON_CAPI_PTR_ATTR,
                              &PyOperation::getCapsule)
       .def(MLIR_PYTHON_CAPI_FACTORY_ATTR, &PyOperation::createFromCapsule)
-      .def_static(
-          "_testing_create_raw_capsule",
-          [](std::string sourceStr) {
-            // Creates a raw context and an operation via parsing the given
-            // source and returns them in a capsule. Error handling is
-            // minimal as this is purely intended for testing interop with
-            // operation creation from capsule functions.
-            MlirContext context = mlirContextCreateWithThreading(false);
-            MlirOperation op = mlirOperationCreateParse(
-                context, toMlirStringRef(sourceStr), toMlirStringRef("temp"));
-            if (mlirOperationIsNull(op)) {
-              mlirContextDestroy(context);
-              throw std::invalid_argument("Failed to parse");
-            }
-            return py::make_tuple(py::reinterpret_steal<py::object>(
-                                      mlirPythonContextToCapsule(context)),
-                                  py::reinterpret_steal<py::object>(
-                                      mlirPythonOperationToCapsule(op)));
-          })
       .def_property_readonly("operation", [](py::object self) { return self; })
       .def_property_readonly("opview", &PyOperation::createOpView)
       .def_property_readonly(
diff --git a/mlir/lib/Bindings/Python/IRModule.h b/mlir/lib/Bindings/Python/IRModule.h
@@ -176,19 +176,8 @@ class PyMlirContext {
   static PyMlirContext *createNewContextForInit();
 
   /// Returns a context reference for the singleton PyMlirContext wrapper for
-  /// the given context. It is only valid to call this on an MlirContext that
-  /// is already owned by the Python bindings. Typically this will be because
-  /// it came in some fashion from createNewContextForInit(). However, it
-  /// is also possible to explicitly transfer ownership of an existing
-  /// MlirContext to the Python bindings via stealExternalContext().
+  /// the given context.
   static PyMlirContextRef forContext(MlirContext context);
-
-  /// Explicitly takes ownership of an MlirContext that must not already be
-  /// known to the Python bindings. Once done, the life-cycle of the context
-  /// will be controlled by the Python bindings, and it will be destroyed
-  /// when the reference count goes to zero.
-  static PyMlirContextRef stealExternalContext(MlirContext context);
-
   ~PyMlirContext();
 
   /// Accesses the underlying MlirContext.
@@ -617,12 +606,6 @@ class PyOperation : public PyOperationBase, public BaseContextObject {
   forOperation(PyMlirContextRef contextRef, MlirOperation operation,
                pybind11::object parentKeepAlive = pybind11::object());
 
-  /// Explicitly takes ownership of an operation that must not already be known
-  /// to the Python bindings. Once done, the life-cycle of the operation
-  /// will be controlled by the Python bindings.
-  static PyOperationRef stealExternalOperation(PyMlirContextRef contextRef,
-                                               MlirOperation operation);
-
   /// Creates a detached operation. The operation must not be associated with
   /// any existing live operation.
   static PyOperationRef
diff --git a/mlir/test/python/ir/context_lifecycle.py b/mlir/test/python/ir/context_lifecycle.py
@@ -45,46 +45,5 @@
 c4 = mlir.ir.Context()
 c4_capsule = c4._CAPIPtr
 assert '"mlir.ir.Context._CAPIPtr"' in repr(c4_capsule)
-# Because the context is already owned by Python, it cannot be created
-# a second time.
-try:
-    c5 = mlir.ir.Context._CAPICreate(c4_capsule)
-except RuntimeError:
-    pass
-else:
-    raise AssertionError(
-        "Should have gotten a RuntimeError when attempting to "
-        "re-create an already owned context"
-    )
-c4 = None
-c4_capsule = None
-gc.collect()
-assert mlir.ir.Context._get_live_count() == 0
-
-# Use a private testing method to create an unowned context capsule and
-# import it.
-c6_capsule = mlir.ir.Context._testing_create_raw_context_capsule()
-c6 = mlir.ir.Context._CAPICreate(c6_capsule)
-assert mlir.ir.Context._get_live_count() == 1
-c6_capsule = None
-c6 = None
-gc.collect()
-assert mlir.ir.Context._get_live_count() == 0
-
-# Also test operation import/export as it is tightly coupled to the context.
-(
-    raw_context_capsule,
-    raw_operation_capsule,
-) = mlir.ir.Operation._testing_create_raw_capsule("builtin.module {}")
-assert '"mlir.ir.Operation._CAPIPtr"' in repr(raw_operation_capsule)
-# Attempting to import an operation for an unknown context should fail.
-try:
-    mlir.ir.Operation._CAPICreate(raw_operation_capsule)
-except RuntimeError:
-    pass
-else:
-    raise AssertionError("Expected exception for unknown context")
-
-# Try again having imported the context.
-c7 = mlir.ir.Context._CAPICreate(raw_context_capsule)
-op7 = mlir.ir.Operation._CAPICreate(raw_operation_capsule)
+c5 = mlir.ir.Context._CAPICreate(c4_capsule)
+assert c4 is c5
diff --git a/mlir/test/python/ir/operation.py b/mlir/test/python/ir/operation.py
@@ -844,6 +844,19 @@ def testOperationName():
         print(op.operation.name)
 
 
+# CHECK-LABEL: TEST: testCapsuleConversions
+@run
+def testCapsuleConversions():
+    ctx = Context()
+    ctx.allow_unregistered_dialects = True
+    with Location.unknown(ctx):
+        m = Operation.create("custom.op1").operation
+        m_capsule = m._CAPIPtr
+        assert '"mlir.ir.Operation._CAPIPtr"' in repr(m_capsule)
+        m2 = Operation._CAPICreate(m_capsule)
+        assert m2 is m
+
+
 # CHECK-LABEL: TEST: testOperationErase
 @run
 def testOperationErase():
