swift

ec3d9dd9 - Optimizer: add the ObjCBridgingOptimization to optimize ObjectiveC bridging operations.

Optimizer: add the ObjCBridgingOptimization to optimize ObjectiveC bridging operations. Removes redundant ObjectiveC <-> Swift bridging calls. Basically, if a value is bridged from ObjectiveC to Swift an then back to ObjectiveC again, then just re-use the original ObjectiveC value. Also in this commit: add an additional DCE pass before ownership elimination. It can cleanup dead code which is left behind by the ObjCBridgingOptimization. rdar://89987440