[all-commits] [llvm/llvm-project] 78bd12: Revert "[mlir][python] Make the Context/Operation ...

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  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 78bd124649ece163d3a26b33608bdbe518d8ff76
      https://github.com/llvm/llvm-project/commit/78bd124649ece163d3a26b33608bdbe518d8ff76
  Author: Alex Zinenko <zinenko at google.com>
  Date:   2023-12-21 (Thu, 21 Dec 2023)

  Changed paths:
    M mlir/lib/Bindings/Python/IRCore.cpp
    M mlir/lib/Bindings/Python/IRModule.h
    M mlir/test/python/ir/context_lifecycle.py
    M mlir/test/python/ir/operation.py

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

This reverts commit bbc29768683b394b34600347f46be2b8245ddb30.

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 39757dfad5be..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 f59b1a26ba48..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

+ at 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
```