[llvm] [RemoveDIs][DebugInfo] Handle DPVAssign in most transforms (PR #78986)

[Stephen Tozer via llvm-commits]

================
@@ -1761,6 +1761,11 @@ bool SimplifyCFGOpt::hoistSuccIdenticalTerminatorToSwitchOrIf(
       OtherSuccTI->replaceAllUsesWith(NT);
     NT->takeName(I1);
   }
+  // Also clone DPValues from the existing terminator, and all others (to
+  // duplicate existing hoisting behaviour).
+  NT->cloneDebugInfoFrom(I1);
+  for (Instruction *OtherSuccTI : OtherSuccTIs)
+    NT->cloneDebugInfoFrom(OtherSuccTI);
----------------
SLTozer wrote:

Nevermind, I was wrong - `DebugInfo/Generic/assignment-tracking/simplifycfg/empty-block.ll` fails without this! Will re-add this to the patch (and also make sure that test is included).

https://github.com/llvm/llvm-project/pull/78986