[mlir][python] Clear PyOperations instead of invalidating them.

`PyOperations` are Python-level handles to `Operation *` instances. When
the latter are modified by C++, the former need to be invalidated.
 llvm#69746 implements such invalidation mechanism by setting all
`PyReferences` to `invalid`. However, that is not enough: they also need
to be removed from the `liveOperations` map since other parts of the
code (such as `PyOperation::createDetached`) assume that that map only
contains valid refs.

This is required to actually solve the issue in llvm#69730.

Author: ingomueller-net

mlir/lib/Bindings/Python/IRCore.cpp

@@ -635,9 +635,12 @@ size_t PyMlirContext::clearLiveOperations() {
   return numInvalidated;
 }
 
-void PyMlirContext::setOperationInvalid(MlirOperation op) {
-  if (liveOperations.contains(op.ptr))
-    liveOperations[op.ptr].second->setInvalid();
+void PyMlirContext::clearOperation(MlirOperation op) {
+  auto it = liveOperations.find(op.ptr);
+  if (it != liveOperations.end()) {
+    it->second.second->setInvalid();
+    liveOperations.erase(it);
+  }
 }
 
 size_t PyMlirContext::getLiveModuleCount() { return liveModules.size(); }

mlir/lib/Bindings/Python/IRModule.h

@@ -209,10 +209,11 @@ class PyMlirContext {
   /// place.
   size_t clearLiveOperations();
 
-  /// Sets an operation invalid. This is useful for when some non-bindings
-  /// code destroys the operation and the bindings need to made aware. For
-  /// example, in the case when pass manager is run.
-  void setOperationInvalid(MlirOperation op);
+  /// Removes an operation from the live operations map and sets it invalid.
+  /// This is useful for when some non-bindings code destroys the operation and
+  /// the bindings need to made aware. For example, in the case when pass
+  /// manager is run.
+  void clearOperation(MlirOperation op);
 
   /// Gets the count of live modules associated with this context.
   /// Used for testing.

mlir/lib/Bindings/Python/Pass.cpp

@@ -130,9 +130,8 @@ void mlir::python::populatePassManagerSubmodule(py::module &m) {
                   [](MlirOperation op, void *userData) {
                     callBackData *data = static_cast<callBackData *>(userData);
                     if (LLVM_LIKELY(data->rootSeen))
-                      data->rootOp.getOperation()
-                          .getContext()
-                          ->setOperationInvalid(op);
+                      data->rootOp.getOperation().getContext()->clearOperation(
+                          op);
                     else
                       data->rootSeen = true;
                   };

mlir/test/python/pass_manager.py

@@ -176,6 +176,14 @@ def testRunPipelineError():
 @run
 def testPostPassOpInvalidation():
     with Context() as ctx:
+        log_op_count = lambda: log("live ops:", ctx._get_live_operation_count())
+
+        # CHECK: invalidate_ops=False
+        log("invalidate_ops=False")
+
+        # CHECK: live ops: 0
+        log_op_count()
+
         module = ModuleOp.parse(
             """
           module {
@@ -188,8 +196,8 @@ def testPostPassOpInvalidation():
         """
         )
 
-        # CHECK: invalidate_ops=False
-        log("invalidate_ops=False")
+        # CHECK: live ops: 1
+        log_op_count()
 
         outer_const_op = module.body.operations[0]
         # CHECK: %[[VAL0:.*]] = arith.constant 10 : i64
@@ -206,6 +214,9 @@ def testPostPassOpInvalidation():
         # CHECK: %[[VAL1]] = arith.constant 10 : i64
         log(inner_const_op)
 
+        # CHECK: live ops: 4
+        log_op_count()
+
         PassManager.parse("builtin.module(canonicalize)").run(
             module, invalidate_ops=False
         )
@@ -222,6 +233,9 @@ def testPostPassOpInvalidation():
         # CHECK: invalidate_ops=True
         log("invalidate_ops=True")
 
+        # CHECK: live ops: 4
+        log_op_count()
+
         module = ModuleOp.parse(
             """
           module {
@@ -237,7 +251,14 @@ def testPostPassOpInvalidation():
         func_op = module.body.operations[1]
         inner_const_op = func_op.body.blocks[0].operations[0]
 
+        # CHECK: live ops: 4
+        log_op_count()
+
         PassManager.parse("builtin.module(canonicalize)").run(module)
+
+        # CHECK: live ops: 1
+        log_op_count()
+
         try:
             log(func_op)
         except RuntimeError as e: