[RemoveDIs] Fix DPValue hoisting in hoistSuccIdenticalTerminatorToSwitchOrIf (#80822)

Follow up to #79476 - that patch added a call to hoistLockstepIdenticalDPValues
which hoists identical DPValues in lockstep, matching dbg intrinsic hoisting
behaviour. The code deleted in this patch, which unconditionally hoists
DPValues, should have been deleted in that patch.

Update test with --try-experimental-debuginfo-iterators to check the behaviour.

Follow up to #79476 - that change introduces a call to
hoistLockstepIdenticalDPValues.

Author: OCHyams

llvm/lib/Transforms/Utils/SimplifyCFG.cpp

@@ -1842,11 +1842,6 @@ bool SimplifyCFGOpt::hoistSuccIdenticalTerminatorToSwitchOrIf(
   Locs.push_back(I1->getDebugLoc());
   for (auto *OtherSuccTI : OtherSuccTIs)
     Locs.push_back(OtherSuccTI->getDebugLoc());
-  // 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);
   NT->setDebugLoc(DILocation::getMergedLocations(Locs));
 
   // PHIs created below will adopt NT's merged DebugLoc.

llvm/test/Transforms/SimplifyCFG/X86/sink-common-code.ll

@@ -1,6 +1,8 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -sink-common-insts -S | FileCheck %s
+; RUN: opt --try-experimental-debuginfo-iterators < %s -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -sink-common-insts -S | FileCheck %s
 ; RUN: opt < %s -passes='simplifycfg<sink-common-insts>' -S | FileCheck %s
+; RUN: opt --try-experimental-debuginfo-iterators < %s -passes='simplifycfg<sink-common-insts>' -S | FileCheck %s
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
 target triple = "x86_64-pc-linux-gnu"