[Mlir-commits] [mlir] [mlir][IR] Add rewriter API for moving operations (PR #78988)

[Matthias Springer]

================
@@ -285,12 +286,17 @@ class OpBuilder : public Builder {
 
     virtual ~Listener() = default;
 
-    /// Notification handler for when an operation is inserted into the builder.
-    /// `op` is the operation that was inserted.
-    virtual void notifyOperationInserted(Operation *op) {}
-
-    /// Notification handler for when a block is created using the builder.
-    /// `block` is the block that was created.
+    /// Notify the listener that the specified operation was inserted.
+    ///
+    /// * If the operation was moved, then `previous` is the previous location
+    ///   of the op.
+    /// * If the operation was unlinked before it was inserted, then `previous`
+    ///   is empty.
+    ///
+    /// Note: Creating an (unlinked) op does not trigger this notification.
+    virtual void notifyOperationInserted(Operation *op, InsertPoint previous) {}
----------------
matthias-springer wrote:

Note: This is similar to what was proposed [here (IR listeners)](https://discourse.llvm.org/t/rfc-introduce-the-concept-of-ir-listeners-in-mlir/67854), but the callback is fired *after* the IR was modified.
```c++
  // This method is called when an operation is inserted into a block. The oldBlock is nullptr is the operation wasn't previously in a block.
  virtual void notifyOpInserted(Operation *op, Block *oldBlock,
                                Block *newBlock) {}
```


https://github.com/llvm/llvm-project/pull/78988