[llvm] 431969e - Revert "[SimplifyCFG] Transform for redirecting phis between unmergeable BB and SuccBB (#67275)"

Muhammad Omair Javaid via llvm-commits llvm-commits at lists.llvm.org
Tue Sep 26 03:48:06 PDT 2023


Author: Muhammad Omair Javaid
Date: 2023-09-26T15:47:16+05:00
New Revision: 431969ede13b0974041e948393d94bca1720c5d7

URL: https://github.com/llvm/llvm-project/commit/431969ede13b0974041e948393d94bca1720c5d7
DIFF: https://github.com/llvm/llvm-project/commit/431969ede13b0974041e948393d94bca1720c5d7.diff

LOG: Revert "[SimplifyCFG] Transform for redirecting phis between unmergeable BB and SuccBB (#67275)"

This reverts commit fc86d031fec5e47c6811efd3a871742ad244afdd.

This change breaks LLVM buildbot clang-aarch64-sve-vls-2stage
https://lab.llvm.org/buildbot/#/builders/176/builds/5474
I am going to revert this patch as the bot has been failing for more than a day without a fix.

Added: 
    

Modified: 
    llvm/lib/Transforms/Utils/Local.cpp
    llvm/test/CodeGen/ARM/jump-table-islands.ll
    llvm/test/Transforms/JumpThreading/codesize-loop.ll
    llvm/test/Transforms/SimplifyCFG/branch-fold.ll
    llvm/test/Transforms/SimplifyCFG/multiple-phis.ll
    llvm/test/Transforms/SimplifyCFG/switch-simplify-crash2.ll

Removed: 
    llvm/test/Transforms/SimplifyCFG/merge-phis-in-switch.ll


################################################################################
diff  --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 47382fefa206aa9..ddb47e693a643d8 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -847,17 +847,17 @@ static bool CanMergeValues(Value *First, Value *Second) {
 /// branch to Succ, into Succ.
 ///
 /// Assumption: Succ is the single successor for BB.
-static bool
-CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ,
-                                const SmallPtrSetImpl<BasicBlock *> &BBPreds) {
+static bool CanPropagatePredecessorsForPHIs(BasicBlock *BB, BasicBlock *Succ) {
   assert(*succ_begin(BB) == Succ && "Succ is not successor of BB!");
 
   LLVM_DEBUG(dbgs() << "Looking to fold " << BB->getName() << " into "
                     << Succ->getName() << "\n");
   // Shortcut, if there is only a single predecessor it must be BB and merging
   // is always safe
-  if (Succ->getSinglePredecessor())
-    return true;
+  if (Succ->getSinglePredecessor()) return true;
+
+  // Make a list of the predecessors of BB
+  SmallPtrSet<BasicBlock*, 16> BBPreds(pred_begin(BB), pred_end(BB));
 
   // Look at all the phi nodes in Succ, to see if they present a conflict when
   // merging these blocks
@@ -997,35 +997,6 @@ static void replaceUndefValuesInPhi(PHINode *PN,
   }
 }
 
-// Only when they shares a single common predecessor, return true.
-// Only handles cases when BB can't be merged while its predecessors can be
-// redirected.
-static bool
-CanRedirectPredsOfEmptyBBToSucc(BasicBlock *BB, BasicBlock *Succ,
-                                const SmallPtrSetImpl<BasicBlock *> &BBPreds,
-                                const SmallPtrSetImpl<BasicBlock *> &SuccPreds,
-                                BasicBlock *&CommonPred) {
-
-  // There must be phis in BB, otherwise BB will be merged into Succ directly
-  if (BB->phis().empty() || Succ->phis().empty())
-    return false;
-
-  // BB must have predecessors not shared that can be redirected to Succ
-  if (!BB->hasNPredecessorsOrMore(2))
-    return false;
-
-  // Get single common predecessors of both BB and Succ
-  for (BasicBlock *SuccPred : SuccPreds) {
-    if (BBPreds.count(SuccPred)) {
-      if (CommonPred)
-        return false;
-      CommonPred = SuccPred;
-    }
-  }
-
-  return true;
-}
-
 /// Replace a value flowing from a block to a phi with
 /// potentially multiple instances of that value flowing from the
 /// block's predecessors to the phi.
@@ -1033,11 +1004,9 @@ CanRedirectPredsOfEmptyBBToSucc(BasicBlock *BB, BasicBlock *Succ,
 /// \param BB The block with the value flowing into the phi.
 /// \param BBPreds The predecessors of BB.
 /// \param PN The phi that we are updating.
-/// \param CommonPred The common predecessor of BB and PN's BasicBlock
 static void redirectValuesFromPredecessorsToPhi(BasicBlock *BB,
                                                 const PredBlockVector &BBPreds,
-                                                PHINode *PN,
-                                                BasicBlock *CommonPred) {
+                                                PHINode *PN) {
   Value *OldVal = PN->removeIncomingValue(BB, false);
   assert(OldVal && "No entry in PHI for Pred BB!");
 
@@ -1065,39 +1034,26 @@ static void redirectValuesFromPredecessorsToPhi(BasicBlock *BB,
       // will trigger asserts if we try to clean it up now, without also
       // simplifying the corresponding conditional branch).
       BasicBlock *PredBB = OldValPN->getIncomingBlock(i);
-
-      if (PredBB == CommonPred)
-        continue;
-
       Value *PredVal = OldValPN->getIncomingValue(i);
-      Value *Selected =
-          selectIncomingValueForBlock(PredVal, PredBB, IncomingValues);
+      Value *Selected = selectIncomingValueForBlock(PredVal, PredBB,
+                                                    IncomingValues);
 
       // And add a new incoming value for this predecessor for the
       // newly retargeted branch.
       PN->addIncoming(Selected, PredBB);
     }
-    if (CommonPred)
-      PN->addIncoming(OldValPN->getIncomingValueForBlock(CommonPred), BB);
-
   } else {
     for (unsigned i = 0, e = BBPreds.size(); i != e; ++i) {
       // Update existing incoming values in PN for this
       // predecessor of BB.
       BasicBlock *PredBB = BBPreds[i];
-
-      if (PredBB == CommonPred)
-        continue;
-
-      Value *Selected =
-          selectIncomingValueForBlock(OldVal, PredBB, IncomingValues);
+      Value *Selected = selectIncomingValueForBlock(OldVal, PredBB,
+                                                    IncomingValues);
 
       // And add a new incoming value for this predecessor for the
       // newly retargeted branch.
       PN->addIncoming(Selected, PredBB);
     }
-    if (CommonPred)
-      PN->addIncoming(OldVal, BB);
   }
 
   replaceUndefValuesInPhi(PN, IncomingValues);
@@ -1108,30 +1064,13 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
   assert(BB != &BB->getParent()->getEntryBlock() &&
          "TryToSimplifyUncondBranchFromEmptyBlock called on entry block!");
 
-  // We can't simplify infinite loops.
+  // We can't eliminate infinite loops.
   BasicBlock *Succ = cast<BranchInst>(BB->getTerminator())->getSuccessor(0);
-  if (BB == Succ)
-    return false;
-
-  SmallPtrSet<BasicBlock *, 16> BBPreds(pred_begin(BB), pred_end(BB));
-  SmallPtrSet<BasicBlock *, 16> SuccPreds(pred_begin(Succ), pred_end(Succ));
+  if (BB == Succ) return false;
 
-  // The single common predecessor of BB and Succ when BB cannot be killed
-  BasicBlock *CommonPred = nullptr;
-
-  bool BBKillable = CanPropagatePredecessorsForPHIs(BB, Succ, BBPreds);
-
-  // Even if we can not fold bB into Succ, we may be able to redirect the
-  // predecessors of BB to Succ.
-  bool BBPhisMergeable =
-      BBKillable ||
-      CanRedirectPredsOfEmptyBBToSucc(BB, Succ, BBPreds, SuccPreds, CommonPred);
-
-  if (!BBKillable && !BBPhisMergeable)
-    return false;
-
-  // Check to see if merging these blocks/phis would cause conflicts for any of
-  // the phi nodes in BB or Succ. If not, we can safely merge.
+  // Check to see if merging these blocks would cause conflicts for any of the
+  // phi nodes in BB or Succ. If not, we can safely merge.
+  if (!CanPropagatePredecessorsForPHIs(BB, Succ)) return false;
 
   // Check for cases where Succ has multiple predecessors and a PHI node in BB
   // has uses which will not disappear when the PHI nodes are merged.  It is
@@ -1160,11 +1099,6 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
     }
   }
 
-  if (BBPhisMergeable && CommonPred)
-    LLVM_DEBUG(dbgs() << "Found Common Predecessor between: " << BB->getName()
-                      << " and " << Succ->getName() << " : "
-                      << CommonPred->getName() << "\n");
-
   // 'BB' and 'BB->Pred' are loop latches, bail out to presrve inner loop
   // metadata.
   //
@@ -1237,37 +1171,25 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
           if (PredTI->hasMetadata(LLVMContext::MD_loop))
             return false;
 
-  if (BBKillable)
-    LLVM_DEBUG(dbgs() << "Killing Trivial BB: \n" << *BB);
-  else if (BBPhisMergeable)
-    LLVM_DEBUG(dbgs() << "Merge Phis in Trivial BB: \n" << *BB);
+  LLVM_DEBUG(dbgs() << "Killing Trivial BB: \n" << *BB);
 
   SmallVector<DominatorTree::UpdateType, 32> Updates;
-
   if (DTU) {
     // To avoid processing the same predecessor more than once.
     SmallPtrSet<BasicBlock *, 8> SeenPreds;
-    // All predecessors of BB (except the common predecessor) will be moved to
-    // Succ.
+    // All predecessors of BB will be moved to Succ.
+    SmallPtrSet<BasicBlock *, 8> PredsOfSucc(pred_begin(Succ), pred_end(Succ));
     Updates.reserve(Updates.size() + 2 * pred_size(BB) + 1);
-
-    for (auto *PredOfBB : predecessors(BB)) {
-      // Do not modify those common predecessors of BB and Succ
-      if (!SuccPreds.contains(PredOfBB))
+    for (auto *PredOfBB : predecessors(BB))
+      // This predecessor of BB may already have Succ as a successor.
+      if (!PredsOfSucc.contains(PredOfBB))
         if (SeenPreds.insert(PredOfBB).second)
           Updates.push_back({DominatorTree::Insert, PredOfBB, Succ});
-    }
-
     SeenPreds.clear();
-
     for (auto *PredOfBB : predecessors(BB))
-      // When BB cannot be killed, do not remove the edge between BB and
-      // CommonPred.
-      if (SeenPreds.insert(PredOfBB).second && PredOfBB != CommonPred)
+      if (SeenPreds.insert(PredOfBB).second)
         Updates.push_back({DominatorTree::Delete, PredOfBB, BB});
-
-    if (BBKillable)
-      Updates.push_back({DominatorTree::Delete, BB, Succ});
+    Updates.push_back({DominatorTree::Delete, BB, Succ});
   }
 
   if (isa<PHINode>(Succ->begin())) {
@@ -1279,19 +1201,21 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
     // Loop over all of the PHI nodes in the successor of BB.
     for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) {
       PHINode *PN = cast<PHINode>(I);
-      redirectValuesFromPredecessorsToPhi(BB, BBPreds, PN, CommonPred);
+
+      redirectValuesFromPredecessorsToPhi(BB, BBPreds, PN);
     }
   }
 
   if (Succ->getSinglePredecessor()) {
     // BB is the only predecessor of Succ, so Succ will end up with exactly
     // the same predecessors BB had.
+
     // Copy over any phi, debug or lifetime instruction.
     BB->getTerminator()->eraseFromParent();
     Succ->splice(Succ->getFirstNonPHI()->getIterator(), BB);
   } else {
     while (PHINode *PN = dyn_cast<PHINode>(&BB->front())) {
-      // We explicitly check for such uses for merging phis.
+      // We explicitly check for such uses in CanPropagatePredecessorsForPHIs.
       assert(PN->use_empty() && "There shouldn't be any uses here!");
       PN->eraseFromParent();
     }
@@ -1304,35 +1228,21 @@ bool llvm::TryToSimplifyUncondBranchFromEmptyBlock(BasicBlock *BB,
       for (BasicBlock *Pred : predecessors(BB))
         Pred->getTerminator()->setMetadata(LLVMContext::MD_loop, LoopMD);
 
-  if (BBKillable) {
-    // Everything that jumped to BB now goes to Succ.
-    BB->replaceAllUsesWith(Succ);
-
-    if (!Succ->hasName())
-      Succ->takeName(BB);
-
-    // Clear the successor list of BB to match updates applying to DTU later.
-    if (BB->getTerminator())
-      BB->back().eraseFromParent();
-
-    new UnreachableInst(BB->getContext(), BB);
-    assert(succ_empty(BB) && "The successor list of BB isn't empty before "
-                             "applying corresponding DTU updates.");
-  } else if (BBPhisMergeable) {
-    //  Everything except CommonPred that jumped to BB now goes to Succ.
-    BB->replaceUsesWithIf(Succ, [BBPreds, CommonPred](Use &U) -> bool {
-      if (Instruction *UseInst = dyn_cast<Instruction>(U.getUser()))
-        return UseInst->getParent() != CommonPred &&
-               BBPreds.contains(UseInst->getParent());
-      return false;
-    });
-  }
+  // Everything that jumped to BB now goes to Succ.
+  BB->replaceAllUsesWith(Succ);
+  if (!Succ->hasName()) Succ->takeName(BB);
+
+  // Clear the successor list of BB to match updates applying to DTU later.
+  if (BB->getTerminator())
+    BB->back().eraseFromParent();
+  new UnreachableInst(BB->getContext(), BB);
+  assert(succ_empty(BB) && "The successor list of BB isn't empty before "
+                           "applying corresponding DTU updates.");
 
   if (DTU)
     DTU->applyUpdates(Updates);
 
-  if (BBKillable)
-    DeleteDeadBlock(BB, DTU);
+  DeleteDeadBlock(BB, DTU);
 
   return true;
 }

diff  --git a/llvm/test/CodeGen/ARM/jump-table-islands.ll b/llvm/test/CodeGen/ARM/jump-table-islands.ll
index e774930bd2bb0b9..c327affc04539b3 100644
--- a/llvm/test/CodeGen/ARM/jump-table-islands.ll
+++ b/llvm/test/CodeGen/ARM/jump-table-islands.ll
@@ -2,8 +2,6 @@
 
 %BigInt = type i8500
 
-declare void @use(%BigInt)
-
 define %BigInt @test_moved_jumptable(i1 %tst, i32 %sw, %BigInt %l) {
 ; CHECK-LABEL: test_moved_jumptable:
 
@@ -36,8 +34,6 @@ other:
 
 end:
   %val = phi %BigInt [ %l, %complex ], [ -1, %simple ]
-; Prevent SimplifyCFG from simplifying the phi node above.
-  call void @use(%BigInt %val)
   ret %BigInt %val
 }
 

diff  --git a/llvm/test/Transforms/JumpThreading/codesize-loop.ll b/llvm/test/Transforms/JumpThreading/codesize-loop.ll
index f01c149ac45a396..a1a2b1dfd15edb2 100644
--- a/llvm/test/Transforms/JumpThreading/codesize-loop.ll
+++ b/llvm/test/Transforms/JumpThreading/codesize-loop.ll
@@ -42,14 +42,16 @@ define i32 @test_minsize(i32 %argc, ptr nocapture readonly %argv) local_unnamed_
 ; OVERIDE-NEXT:    [[TMP3:%.*]] = mul i32 [[CALL]], [[TMP2]]
 ; OVERIDE-NEXT:    [[TMP4:%.*]] = icmp sgt i32 [[CALL]], 0
 ; OVERIDE-NEXT:    [[COND_FR:%.*]] = freeze i1 [[TMP4]]
-; OVERIDE-NEXT:    br i1 [[COND_FR]], label [[TMP5:%.*]], label [[COND_END_THREAD]]
-; OVERIDE:       5:
-; OVERIDE-NEXT:    br label [[COND_END_THREAD]]
+; OVERIDE-NEXT:    br i1 [[COND_FR]], label [[COND_END_THREAD]], label [[TMP6:%.*]]
 ; OVERIDE:       cond.end.thread:
-; OVERIDE-NEXT:    [[TMP6:%.*]] = phi i32 [ [[TMP3]], [[COND_END]] ], [ [[TMP3]], [[TMP5]] ], [ 205962976, [[ENTRY:%.*]] ]
-; OVERIDE-NEXT:    [[TMP7:%.*]] = phi i32 [ 0, [[COND_END]] ], [ [[CALL]], [[TMP5]] ], [ 46, [[ENTRY]] ]
-; OVERIDE-NEXT:    [[TMP8:%.*]] = mul i32 [[TMP6]], [[TMP7]]
-; OVERIDE-NEXT:    [[CALL33:%.*]] = tail call i32 (ptr, ...) @printf(ptr nonnull dereferenceable(1) @.str, i32 [[TMP8]])
+; OVERIDE-NEXT:    [[TMP5:%.*]] = phi i32 [ [[TMP3]], [[COND_END]] ], [ 205962976, [[ENTRY:%.*]] ]
+; OVERIDE-NEXT:    [[COND3:%.*]] = phi i32 [ [[CALL]], [[COND_END]] ], [ 46, [[ENTRY]] ]
+; OVERIDE-NEXT:    br label [[TMP6]]
+; OVERIDE:       6:
+; OVERIDE-NEXT:    [[TMP7:%.*]] = phi i32 [ [[TMP5]], [[COND_END_THREAD]] ], [ [[TMP3]], [[COND_END]] ]
+; OVERIDE-NEXT:    [[TMP8:%.*]] = phi i32 [ [[COND3]], [[COND_END_THREAD]] ], [ 0, [[COND_END]] ]
+; OVERIDE-NEXT:    [[TMP9:%.*]] = mul i32 [[TMP7]], [[TMP8]]
+; OVERIDE-NEXT:    [[CALL33:%.*]] = tail call i32 (ptr, ...) @printf(ptr nonnull dereferenceable(1) @.str, i32 [[TMP9]])
 ; OVERIDE-NEXT:    ret i32 0
 ;
 entry:
@@ -88,14 +90,16 @@ define i32 @test_optsize(i32 %argc, ptr nocapture readonly %argv) local_unnamed_
 ; DEFAULT-NEXT:    [[TMP3:%.*]] = mul i32 [[CALL]], [[TMP2]]
 ; DEFAULT-NEXT:    [[TMP4:%.*]] = icmp sgt i32 [[CALL]], 0
 ; DEFAULT-NEXT:    [[COND_FR:%.*]] = freeze i1 [[TMP4]]
-; DEFAULT-NEXT:    br i1 [[COND_FR]], label [[TMP5:%.*]], label [[COND_END_THREAD]]
-; DEFAULT:       5:
-; DEFAULT-NEXT:    br label [[COND_END_THREAD]]
+; DEFAULT-NEXT:    br i1 [[COND_FR]], label [[COND_END_THREAD]], label [[TMP6:%.*]]
 ; DEFAULT:       cond.end.thread:
-; DEFAULT-NEXT:    [[TMP6:%.*]] = phi i32 [ [[TMP3]], [[COND_END]] ], [ [[TMP3]], [[TMP5]] ], [ 205962976, [[ENTRY:%.*]] ]
-; DEFAULT-NEXT:    [[TMP7:%.*]] = phi i32 [ 0, [[COND_END]] ], [ [[CALL]], [[TMP5]] ], [ 46, [[ENTRY]] ]
-; DEFAULT-NEXT:    [[TMP8:%.*]] = mul i32 [[TMP6]], [[TMP7]]
-; DEFAULT-NEXT:    [[CALL33:%.*]] = tail call i32 (ptr, ...) @printf(ptr nonnull dereferenceable(1) @.str, i32 [[TMP8]])
+; DEFAULT-NEXT:    [[TMP5:%.*]] = phi i32 [ [[TMP3]], [[COND_END]] ], [ 205962976, [[ENTRY:%.*]] ]
+; DEFAULT-NEXT:    [[COND3:%.*]] = phi i32 [ [[CALL]], [[COND_END]] ], [ 46, [[ENTRY]] ]
+; DEFAULT-NEXT:    br label [[TMP6]]
+; DEFAULT:       6:
+; DEFAULT-NEXT:    [[TMP7:%.*]] = phi i32 [ [[TMP5]], [[COND_END_THREAD]] ], [ [[TMP3]], [[COND_END]] ]
+; DEFAULT-NEXT:    [[TMP8:%.*]] = phi i32 [ [[COND3]], [[COND_END_THREAD]] ], [ 0, [[COND_END]] ]
+; DEFAULT-NEXT:    [[TMP9:%.*]] = mul i32 [[TMP7]], [[TMP8]]
+; DEFAULT-NEXT:    [[CALL33:%.*]] = tail call i32 (ptr, ...) @printf(ptr nonnull dereferenceable(1) @.str, i32 [[TMP9]])
 ; DEFAULT-NEXT:    ret i32 0
 ;
 ; OVERIDE-LABEL: @test_optsize(
@@ -111,14 +115,16 @@ define i32 @test_optsize(i32 %argc, ptr nocapture readonly %argv) local_unnamed_
 ; OVERIDE-NEXT:    [[TMP3:%.*]] = mul i32 [[CALL]], [[TMP2]]
 ; OVERIDE-NEXT:    [[TMP4:%.*]] = icmp sgt i32 [[CALL]], 0
 ; OVERIDE-NEXT:    [[COND_FR:%.*]] = freeze i1 [[TMP4]]
-; OVERIDE-NEXT:    br i1 [[COND_FR]], label [[TMP5:%.*]], label [[COND_END_THREAD]]
-; OVERIDE:       5:
-; OVERIDE-NEXT:    br label [[COND_END_THREAD]]
+; OVERIDE-NEXT:    br i1 [[COND_FR]], label [[COND_END_THREAD]], label [[TMP6:%.*]]
 ; OVERIDE:       cond.end.thread:
-; OVERIDE-NEXT:    [[TMP6:%.*]] = phi i32 [ [[TMP3]], [[COND_END]] ], [ [[TMP3]], [[TMP5]] ], [ 205962976, [[ENTRY:%.*]] ]
-; OVERIDE-NEXT:    [[TMP7:%.*]] = phi i32 [ 0, [[COND_END]] ], [ [[CALL]], [[TMP5]] ], [ 46, [[ENTRY]] ]
-; OVERIDE-NEXT:    [[TMP8:%.*]] = mul i32 [[TMP6]], [[TMP7]]
-; OVERIDE-NEXT:    [[CALL33:%.*]] = tail call i32 (ptr, ...) @printf(ptr nonnull dereferenceable(1) @.str, i32 [[TMP8]])
+; OVERIDE-NEXT:    [[TMP5:%.*]] = phi i32 [ [[TMP3]], [[COND_END]] ], [ 205962976, [[ENTRY:%.*]] ]
+; OVERIDE-NEXT:    [[COND3:%.*]] = phi i32 [ [[CALL]], [[COND_END]] ], [ 46, [[ENTRY]] ]
+; OVERIDE-NEXT:    br label [[TMP6]]
+; OVERIDE:       6:
+; OVERIDE-NEXT:    [[TMP7:%.*]] = phi i32 [ [[TMP5]], [[COND_END_THREAD]] ], [ [[TMP3]], [[COND_END]] ]
+; OVERIDE-NEXT:    [[TMP8:%.*]] = phi i32 [ [[COND3]], [[COND_END_THREAD]] ], [ 0, [[COND_END]] ]
+; OVERIDE-NEXT:    [[TMP9:%.*]] = mul i32 [[TMP7]], [[TMP8]]
+; OVERIDE-NEXT:    [[CALL33:%.*]] = tail call i32 (ptr, ...) @printf(ptr nonnull dereferenceable(1) @.str, i32 [[TMP9]])
 ; OVERIDE-NEXT:    ret i32 0
 ;
 entry:

diff  --git a/llvm/test/Transforms/SimplifyCFG/branch-fold.ll b/llvm/test/Transforms/SimplifyCFG/branch-fold.ll
index 2f5fb4f33013d2e..b8b5aaa73cf501c 100644
--- a/llvm/test/Transforms/SimplifyCFG/branch-fold.ll
+++ b/llvm/test/Transforms/SimplifyCFG/branch-fold.ll
@@ -114,35 +114,3 @@ bb0:
   call void @foo()
   ret void
 }
-
-define i8 @common_pred(i8 noundef %arg, i1 %c1, i1 %c2) {
-; CHECK-LABEL: @common_pred(
-; CHECK-NEXT:  Pred:
-; CHECK-NEXT:    call void @dummy()
-; CHECK-NEXT:    br i1 [[C1:%.*]], label [[COMMONPRED:%.*]], label [[SUCC:%.*]]
-; CHECK:       CommonPred:
-; CHECK-NEXT:    call void @dummy()
-; CHECK-NEXT:    [[SPEC_SELECT:%.*]] = select i1 [[C2:%.*]], i8 4, i8 1
-; CHECK-NEXT:    br label [[SUCC]]
-; CHECK:       Succ:
-; CHECK-NEXT:    [[PHI2:%.*]] = phi i8 [ 0, [[PRED:%.*]] ], [ [[SPEC_SELECT]], [[COMMONPRED]] ]
-; CHECK-NEXT:    ret i8 [[PHI2]]
-;
-Pred:
-call void @dummy()
-  br i1 %c1, label %CommonPred, label %BB
-
-CommonPred:
-call void @dummy()
-  br i1 %c2, label %Succ, label %BB
-
-BB:
-  %phi1 = phi i8 [ 0, %Pred ], [1, %CommonPred]
-  br label %Succ
-
-Succ:
-  %phi2 = phi i8 [ %phi1, %BB ], [ 4, %CommonPred ]
-  ret i8 %phi2
-}
-
-declare void @dummy()

diff  --git a/llvm/test/Transforms/SimplifyCFG/merge-phis-in-switch.ll b/llvm/test/Transforms/SimplifyCFG/merge-phis-in-switch.ll
deleted file mode 100644
index 0ffa53a5c9e1049..000000000000000
--- a/llvm/test/Transforms/SimplifyCFG/merge-phis-in-switch.ll
+++ /dev/null
@@ -1,327 +0,0 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 3
-; RUN: opt < %s -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -S | FileCheck %s
-
-; Test a bunch of cases where the combination of phis in switch should be merged into one phi
-
-declare void @use(i8)
-
-define i8 @phis_of_switch_minimal(i8 noundef %arg) {
-; CHECK-LABEL: define i8 @phis_of_switch_minimal
-; CHECK-SAME: (i8 noundef [[ARG:%.*]]) {
-; CHECK-NEXT:  start:
-; CHECK-NEXT:    switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
-; CHECK-NEXT:    i8 0, label [[CASE01:%.*]]
-; CHECK-NEXT:    i8 1, label [[CASE1:%.*]]
-; CHECK-NEXT:    i8 2, label [[END:%.*]]
-; CHECK-NEXT:    ]
-; CHECK:       unreachable:
-; CHECK-NEXT:    unreachable
-; CHECK:       case1:
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       case01:
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       end:
-; CHECK-NEXT:    [[PHI2:%.*]] = phi i8 [ 3, [[START:%.*]] ], [ 2, [[CASE1]] ], [ 1, [[CASE01]] ]
-; CHECK-NEXT:    ret i8 [[PHI2]]
-;
-start:
-  switch i8 %arg, label %unreachable [
-  i8 0, label %case01
-  i8 1, label %case1
-  i8 2, label %end
-  ]
-unreachable:
-  unreachable
-case1:
-  br label %case01
-
-case01:
-  %phi1 = phi i8 [ 2, %case1 ], [1, %start]
-  br label %end
-
-end:
-  %phi2 = phi i8 [ %phi1, %case01 ], [ 3, %start ]
-  ret i8 %phi2
-}
-
-define i8 @phis_of_switch(i8 noundef %arg) {
-; CHECK-LABEL: define i8 @phis_of_switch
-; CHECK-SAME: (i8 noundef [[ARG:%.*]]) {
-; CHECK-NEXT:  start:
-; CHECK-NEXT:    switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
-; CHECK-NEXT:    i8 0, label [[CASE012:%.*]]
-; CHECK-NEXT:    i8 1, label [[CASE1:%.*]]
-; CHECK-NEXT:    i8 2, label [[CASE2:%.*]]
-; CHECK-NEXT:    i8 3, label [[END:%.*]]
-; CHECK-NEXT:    ]
-; CHECK:       unreachable:
-; CHECK-NEXT:    unreachable
-; CHECK:       case1:
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       case2:
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       case012:
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       end:
-; CHECK-NEXT:    [[PHI2:%.*]] = phi i8 [ 4, [[START:%.*]] ], [ 3, [[CASE2]] ], [ 2, [[CASE1]] ], [ 1, [[CASE012]] ]
-; CHECK-NEXT:    ret i8 [[PHI2]]
-;
-start:
-  switch i8 %arg, label %unreachable [
-  i8 0, label %case012
-  i8 1, label %case1
-  i8 2, label %case2
-  i8 3, label %end
-  ]
-unreachable:
-  unreachable
-case1:
-  br label %case012
-
-case2:
-  br label %case012
-
-case012:
-  %phi1 = phi i8 [ 3, %case2 ], [ 2, %case1 ], [1, %start]
-  br label %end
-
-end:
-  %phi2 = phi i8 [ %phi1, %case012 ], [ 4, %start ]
-  ret i8 %phi2
-}
-
-define i8 @multiple_phis_of_switch(i8 noundef %arg) {
-; CHECK-LABEL: define i8 @multiple_phis_of_switch
-; CHECK-SAME: (i8 noundef [[ARG:%.*]]) {
-; CHECK-NEXT:  start:
-; CHECK-NEXT:    switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
-; CHECK-NEXT:    i8 0, label [[CASE012:%.*]]
-; CHECK-NEXT:    i8 1, label [[CASE1:%.*]]
-; CHECK-NEXT:    i8 2, label [[CASE2:%.*]]
-; CHECK-NEXT:    i8 3, label [[END:%.*]]
-; CHECK-NEXT:    ]
-; CHECK:       unreachable:
-; CHECK-NEXT:    unreachable
-; CHECK:       case1:
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       case2:
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       case012:
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       end:
-; CHECK-NEXT:    [[PHI2_1:%.*]] = phi i8 [ 4, [[START:%.*]] ], [ 3, [[CASE2]] ], [ 2, [[CASE1]] ], [ 1, [[CASE012]] ]
-; CHECK-NEXT:    [[PHI2_2:%.*]] = phi i8 [ 5, [[START]] ], [ 3, [[CASE2]] ], [ 2, [[CASE1]] ], [ 1, [[CASE012]] ]
-; CHECK-NEXT:    [[PHI2_3:%.*]] = phi i8 [ 3, [[START]] ], [ 6, [[CASE2]] ], [ 5, [[CASE1]] ], [ 4, [[CASE012]] ]
-; CHECK-NEXT:    call void @use(i8 [[PHI2_1]])
-; CHECK-NEXT:    call void @use(i8 [[PHI2_2]])
-; CHECK-NEXT:    call void @use(i8 [[PHI2_3]])
-; CHECK-NEXT:    ret i8 [[PHI2_1]]
-;
-start:
-  switch i8 %arg, label %unreachable [
-  i8 0, label %case012
-  i8 1, label %case1
-  i8 2, label %case2
-  i8 3, label %end
-  ]
-unreachable:
-  unreachable
-case1:
-  br label %case012
-
-case2:
-  br label %case012
-
-case012:
-  %phi1_1 = phi i8 [ 3, %case2 ], [ 2, %case1 ], [1, %start]
-  %phi1_2 = phi i8 [ 6, %case2 ], [ 5, %case1 ], [4, %start]
-  br label %end
-
-end:
-  %phi2_1 = phi i8 [ %phi1_1, %case012 ], [ 4, %start ]
-  %phi2_2 = phi i8 [ %phi1_1, %case012 ], [ 5, %start ]
-  %phi2_3 = phi i8 [ %phi1_2, %case012 ], [ 3, %start ]
-  call void @use(i8 %phi2_1)
-  call void @use(i8 %phi2_2)
-  call void @use(i8 %phi2_3)
-  ret i8 %phi2_1
-}
-
-define i8 @phis_of_switch_multiple_stage0(i8 noundef %arg) {
-; CHECK-LABEL: define i8 @phis_of_switch_multiple_stage0
-; CHECK-SAME: (i8 noundef [[ARG:%.*]]) {
-; CHECK-NEXT:  start:
-; CHECK-NEXT:    switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
-; CHECK-NEXT:    i8 0, label [[CASE0:%.*]]
-; CHECK-NEXT:    i8 1, label [[CASE1:%.*]]
-; CHECK-NEXT:    i8 2, label [[CASE2:%.*]]
-; CHECK-NEXT:    i8 3, label [[CASE0123:%.*]]
-; CHECK-NEXT:    i8 4, label [[CASE01234:%.*]]
-; CHECK-NEXT:    i8 5, label [[END:%.*]]
-; CHECK-NEXT:    ]
-; CHECK:       unreachable:
-; CHECK-NEXT:    unreachable
-; CHECK:       case0:
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       case1:
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       case2:
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       case0123:
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       case01234:
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       end:
-; CHECK-NEXT:    [[PHI3:%.*]] = phi i8 [ 6, [[START:%.*]] ], [ 3, [[CASE2]] ], [ 2, [[CASE1]] ], [ 1, [[CASE0]] ], [ 4, [[CASE0123]] ], [ 5, [[CASE01234]] ]
-; CHECK-NEXT:    ret i8 [[PHI3]]
-;
-start:
-  switch i8 %arg, label %unreachable [
-  i8 0, label %case0
-  i8 1, label %case1
-  i8 2, label %case2
-  i8 3, label %case0123
-  i8 4, label %case01234
-  i8 5, label %end
-  ]
-unreachable:
-  unreachable
-
-case0:
-  br label %case0123
-
-case1:
-  br label %case0123
-
-case2:
-  br label %case0123
-
-case0123:
-  %phi1 = phi i8 [4, %start], [ 3, %case2 ], [ 2, %case1 ], [ 1, %case0 ]
-  br label %case01234
-
-case01234:
-  %phi2 = phi i8 [ %phi1, %case0123 ], [ 5, %start ]
-  br label %end
-
-end:
-  %phi3 = phi i8 [ %phi2, %case01234 ], [6, %start]
-  ret i8 %phi3
-}
-
-define i8 @phis_of_switch_multiple_stage1(i8 noundef %arg) {
-; CHECK-LABEL: define i8 @phis_of_switch_multiple_stage1
-; CHECK-SAME: (i8 noundef [[ARG:%.*]]) {
-; CHECK-NEXT:  start:
-; CHECK-NEXT:    switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
-; CHECK-NEXT:    i8 0, label [[CASE0:%.*]]
-; CHECK-NEXT:    i8 1, label [[CASE1:%.*]]
-; CHECK-NEXT:    i8 2, label [[CASE012:%.*]]
-; CHECK-NEXT:    i8 3, label [[CASE3:%.*]]
-; CHECK-NEXT:    i8 4, label [[CASE4:%.*]]
-; CHECK-NEXT:    i8 5, label [[CASE345:%.*]]
-; CHECK-NEXT:    i8 6, label [[CASE0123456:%.*]]
-; CHECK-NEXT:    ]
-; CHECK:       unreachable:
-; CHECK-NEXT:    unreachable
-; CHECK:       case0:
-; CHECK-NEXT:    br label [[CASE0123456]]
-; CHECK:       case1:
-; CHECK-NEXT:    br label [[CASE0123456]]
-; CHECK:       case012:
-; CHECK-NEXT:    br label [[CASE0123456]]
-; CHECK:       case3:
-; CHECK-NEXT:    br label [[CASE0123456]]
-; CHECK:       case4:
-; CHECK-NEXT:    br label [[CASE0123456]]
-; CHECK:       case345:
-; CHECK-NEXT:    br label [[CASE0123456]]
-; CHECK:       case0123456:
-; CHECK-NEXT:    [[PHI1234567:%.*]] = phi i8 [ 7, [[START:%.*]] ], [ 2, [[CASE1]] ], [ 1, [[CASE0]] ], [ 3, [[CASE012]] ], [ 5, [[CASE4]] ], [ 4, [[CASE3]] ], [ 6, [[CASE345]] ]
-; CHECK-NEXT:    ret i8 [[PHI1234567]]
-;
-start:
-  switch i8 %arg, label %unreachable [
-  i8 0, label %case0
-  i8 1, label %case1
-  i8 2, label %case012
-  i8 3, label %case3
-  i8 4, label %case4
-  i8 5, label %case345
-  i8 6, label %case0123456
-  ]
-unreachable:
-  unreachable
-case0:
-  br label %case012
-
-case1:
-  br label %case012
-
-case012:
-  %phi123 = phi i8 [3, %start], [ 2, %case1 ], [ 1, %case0 ]
-  br label %case0123456
-
-case3:
-  br label %case345
-
-case4:
-  br label %case345
-
-case345:
-  %phi456 = phi i8 [6, %start], [ 5, %case4 ], [ 4, %case3 ]
-  br label %case0123456
-
-case0123456:
-  %phi1234567 = phi i8 [7, %start], [ %phi456, %case345 ], [ %phi123, %case012 ]
-  ret i8 %phi1234567
-
-}
-
-define i8 @phis_of_switch_extra_use_fail(i8 noundef %arg) {
-; CHECK-LABEL: define i8 @phis_of_switch_extra_use_fail
-; CHECK-SAME: (i8 noundef [[ARG:%.*]]) {
-; CHECK-NEXT:  start:
-; CHECK-NEXT:    switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
-; CHECK-NEXT:    i8 0, label [[CASE012:%.*]]
-; CHECK-NEXT:    i8 1, label [[CASE1:%.*]]
-; CHECK-NEXT:    i8 2, label [[CASE2:%.*]]
-; CHECK-NEXT:    i8 3, label [[END:%.*]]
-; CHECK-NEXT:    ]
-; CHECK:       unreachable:
-; CHECK-NEXT:    unreachable
-; CHECK:       case1:
-; CHECK-NEXT:    br label [[CASE012]]
-; CHECK:       case2:
-; CHECK-NEXT:    br label [[CASE012]]
-; CHECK:       case012:
-; CHECK-NEXT:    [[PHI1:%.*]] = phi i8 [ 3, [[CASE2]] ], [ 2, [[CASE1]] ], [ 1, [[START:%.*]] ]
-; CHECK-NEXT:    call void @use(i8 [[PHI1]])
-; CHECK-NEXT:    br label [[END]]
-; CHECK:       end:
-; CHECK-NEXT:    [[PHI2:%.*]] = phi i8 [ [[PHI1]], [[CASE012]] ], [ 4, [[START]] ]
-; CHECK-NEXT:    ret i8 [[PHI2]]
-;
-start:
-  switch i8 %arg, label %unreachable [
-  i8 0, label %case012
-  i8 1, label %case1
-  i8 2, label %case2 i8 3, label %end
-  ]
-unreachable:
-  unreachable
-case1:
-  br label %case012
-
-case2:
-  br label %case012
-
-case012:
-  %phi1 = phi i8 [ 3, %case2 ], [ 2, %case1 ], [1, %start]
-  call void @use(i8 %phi1)
-  br label %end
-
-end:
-  %phi2 = phi i8 [ %phi1, %case012 ], [ 4, %start ]
-  ret i8 %phi2
-}

diff  --git a/llvm/test/Transforms/SimplifyCFG/multiple-phis.ll b/llvm/test/Transforms/SimplifyCFG/multiple-phis.ll
index d63973eab71e474..eae851f2ddadae9 100644
--- a/llvm/test/Transforms/SimplifyCFG/multiple-phis.ll
+++ b/llvm/test/Transforms/SimplifyCFG/multiple-phis.ll
@@ -1,5 +1,4 @@
-; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 2
-
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt -passes=simplifycfg -simplifycfg-require-and-preserve-domtree=1 -keep-loops=false -S < %s | FileCheck %s
 ; RUN: opt -passes='simplifycfg<no-keep-loops>' -S < %s | FileCheck %s
 
@@ -8,12 +7,11 @@
 ; SimplifyCFG if-converts one of the phis, it should do both.
 
 define i32 @upper_bound(ptr %r, i32 %high, i32 %k) nounwind {
-; CHECK-LABEL: define i32 @upper_bound
-; CHECK-SAME: (ptr [[R:%.*]], i32 [[HIGH:%.*]], i32 [[K:%.*]]) #[[ATTR0:[0-9]+]] {
+; CHECK-LABEL: @upper_bound(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[WHILE_COND:%.*]]
 ; CHECK:       while.cond:
-; CHECK-NEXT:    [[HIGH_ADDR_0:%.*]] = phi i32 [ [[HIGH]], [[ENTRY:%.*]] ], [ [[SPEC_SELECT:%.*]], [[WHILE_BODY:%.*]] ]
+; CHECK-NEXT:    [[HIGH_ADDR_0:%.*]] = phi i32 [ [[HIGH:%.*]], [[ENTRY:%.*]] ], [ [[SPEC_SELECT:%.*]], [[WHILE_BODY:%.*]] ]
 ; CHECK-NEXT:    [[LOW_0:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[SPEC_SELECT1:%.*]], [[WHILE_BODY]] ]
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[LOW_0]], [[HIGH_ADDR_0]]
 ; CHECK-NEXT:    br i1 [[CMP]], label [[WHILE_BODY]], label [[WHILE_END:%.*]]
@@ -21,9 +19,9 @@ define i32 @upper_bound(ptr %r, i32 %high, i32 %k) nounwind {
 ; CHECK-NEXT:    [[ADD:%.*]] = add i32 [[LOW_0]], [[HIGH_ADDR_0]]
 ; CHECK-NEXT:    [[DIV:%.*]] = udiv i32 [[ADD]], 2
 ; CHECK-NEXT:    [[IDXPROM:%.*]] = zext i32 [[DIV]] to i64
-; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, ptr [[R]], i64 [[IDXPROM]]
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, ptr [[R:%.*]], i64 [[IDXPROM]]
 ; CHECK-NEXT:    [[TMP0:%.*]] = load i32, ptr [[ARRAYIDX]], align 4
-; CHECK-NEXT:    [[CMP1:%.*]] = icmp ult i32 [[K]], [[TMP0]]
+; CHECK-NEXT:    [[CMP1:%.*]] = icmp ult i32 [[K:%.*]], [[TMP0]]
 ; CHECK-NEXT:    [[ADD2:%.*]] = add i32 [[DIV]], 1
 ; CHECK-NEXT:    [[SPEC_SELECT]] = select i1 [[CMP1]], i32 [[DIV]], i32 [[HIGH_ADDR_0]]
 ; CHECK-NEXT:    [[SPEC_SELECT1]] = select i1 [[CMP1]], i32 [[LOW_0]], i32 [[ADD2]]
@@ -59,270 +57,3 @@ if.else:                                          ; preds = %while.body
 while.end:                                        ; preds = %while.cond
   ret i32 %low.0
 }
-
-define i32 @merge0(i1 %c1, i1 %c2, i1 %c3) {
-; CHECK-LABEL: define i32 @merge0
-; CHECK-SAME: (i1 [[C1:%.*]], i1 [[C2:%.*]], i1 [[C3:%.*]]) {
-; CHECK-NEXT:  j2:
-; CHECK-NEXT:    [[DOT:%.*]] = select i1 [[C2]], i32 0, i32 1
-; CHECK-NEXT:    [[SPEC_SELECT:%.*]] = select i1 [[C3]], i32 2, i32 3
-; CHECK-NEXT:    [[PHI2:%.*]] = select i1 [[C1]], i32 [[DOT]], i32 [[SPEC_SELECT]]
-; CHECK-NEXT:    ret i32 [[PHI2]]
-;
-  br i1 %c1, label %if1, label %else1
-
-if1:
-  br i1 %c2, label %if2, label %else2
-
-if2:
-  br label %j1 else2:
-  br label %j1
-
-else1:
-  br i1 %c3, label %j1, label %j2
-
-j1:
-  %phi1 = phi i32 [ 0, %if2 ], [ 1, %else2 ], [ 2, %else1 ]
-  br label %j2
-
-j2:
-  %phi2 = phi i32 [ %phi1, %j1 ], [ 3, %else1 ]
-  ret i32 %phi2
-}
-
-define i8 @merge1(i8 noundef %arg, i1 %c1, i1 %c2) {
-; CHECK-LABEL: define i8 @merge1
-; CHECK-SAME: (i8 noundef [[ARG:%.*]], i1 [[C1:%.*]], i1 [[C2:%.*]]) {
-; CHECK-NEXT:  entry:
-; CHECK-NEXT:    switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
-; CHECK-NEXT:    i8 -123, label [[CASE0:%.*]]
-; CHECK-NEXT:    i8 66, label [[SUCC:%.*]]
-; CHECK-NEXT:    i8 123, label [[CASE2:%.*]]
-; CHECK-NEXT:    ]
-; CHECK:       unreachable:
-; CHECK-NEXT:    unreachable
-; CHECK:       case0:
-; CHECK-NEXT:    [[C1_NOT:%.*]] = xor i1 [[C1]], true
-; CHECK-NEXT:    [[C2_NOT:%.*]] = xor i1 [[C2]], true
-; CHECK-NEXT:    [[BRMERGE:%.*]] = select i1 [[C1_NOT]], i1 true, i1 [[C2_NOT]]
-; CHECK-NEXT:    [[DOTMUX:%.*]] = select i1 [[C1_NOT]], i8 0, i8 3
-; CHECK-NEXT:    [[SPEC_SELECT:%.*]] = select i1 [[BRMERGE]], i8 [[DOTMUX]], i8 4
-; CHECK-NEXT:    br label [[SUCC]]
-; CHECK:       case2:
-; CHECK-NEXT:    br label [[SUCC]]
-; CHECK:       Succ:
-; CHECK-NEXT:    [[PHI2:%.*]] = phi i8 [ 2, [[CASE2]] ], [ 1, [[ENTRY:%.*]] ], [ [[SPEC_SELECT]], [[CASE0]] ]
-; CHECK-NEXT:    ret i8 [[PHI2]]
-;
-entry:
-  switch i8 %arg, label %unreachable [
-  i8 -123, label %case0
-  i8 66, label %case1
-  i8 123, label %case2
-  ]
-
-unreachable:
-  unreachable
-
-case0:
-  br i1 %c1, label %CommonPred, label %BB
-
-case1:
-  br label %BB
-
-case2:
-  br label %BB
-
-CommonPred:
-  br i1 %c2, label %Succ, label %BB
-
-BB:
-  %phi1 = phi i8 [ 0, %case0 ], [1, %case1],[2, %case2],[3,%CommonPred]
-  br label %Succ
-
-Succ:
-  %phi2 = phi i8 [ %phi1, %BB ], [ 4, %CommonPred ]
-  ret i8 %phi2
-}
-
-define i8 @merge1_unfoldable_one_block(i8 noundef %arg, i1 %c1, i1 %c2) {
-; CHECK-LABEL: define i8 @merge1_unfoldable_one_block
-; CHECK-SAME: (i8 noundef [[ARG:%.*]], i1 [[C1:%.*]], i1 [[C2:%.*]]) {
-; CHECK-NEXT:  entry:
-; CHECK-NEXT:    switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
-; CHECK-NEXT:    i8 -123, label [[CASE0:%.*]]
-; CHECK-NEXT:    i8 66, label [[SUCC:%.*]]
-; CHECK-NEXT:    i8 123, label [[CASE2:%.*]]
-; CHECK-NEXT:    ]
-; CHECK:       unreachable:
-; CHECK-NEXT:    unreachable
-; CHECK:       case0:
-; CHECK-NEXT:    call void @dummy()
-; CHECK-NEXT:    [[C1_NOT:%.*]] = xor i1 [[C1]], true
-; CHECK-NEXT:    [[C2_NOT:%.*]] = xor i1 [[C2]], true
-; CHECK-NEXT:    [[BRMERGE:%.*]] = select i1 [[C1_NOT]], i1 true, i1 [[C2_NOT]]
-; CHECK-NEXT:    [[DOTMUX:%.*]] = select i1 [[C1_NOT]], i8 0, i8 3
-; CHECK-NEXT:    [[SPEC_SELECT:%.*]] = select i1 [[BRMERGE]], i8 [[DOTMUX]], i8 4
-; CHECK-NEXT:    br label [[SUCC]]
-; CHECK:       case2:
-; CHECK-NEXT:    br label [[SUCC]]
-; CHECK:       Succ:
-; CHECK-NEXT:    [[PHI2:%.*]] = phi i8 [ 2, [[CASE2]] ], [ 1, [[ENTRY:%.*]] ], [ [[SPEC_SELECT]], [[CASE0]] ]
-; CHECK-NEXT:    ret i8 [[PHI2]]
-;
-entry:
-  switch i8 %arg, label %unreachable [
-  i8 -123, label %case0
-  i8 66, label %case1
-  i8 123, label %case2
-  ]
-
-unreachable:
-  unreachable
-
-case0:
-  call void @dummy()
-  br i1 %c1, label %CommonPred, label %BB
-
-case1:
-  br label %BB
-
-case2:
-  br label %BB
-
-CommonPred:
-  br i1 %c2, label %Succ, label %BB
-
-BB:
-  %phi1 = phi i8 [ 0, %case0 ], [1, %case1],[2, %case2],[3,%CommonPred]
-  br label %Succ
-
-Succ:
-  %phi2 = phi i8 [ %phi1, %BB ], [ 4, %CommonPred ]
-  ret i8 %phi2
-}
-
-define i8 @merge1_unfoldable_two_block(i8 noundef %arg, i1 %c1, i1 %c2) {
-; CHECK-LABEL: define i8 @merge1_unfoldable_two_block
-; CHECK-SAME: (i8 noundef [[ARG:%.*]], i1 [[C1:%.*]], i1 [[C2:%.*]]) {
-; CHECK-NEXT:  entry:
-; CHECK-NEXT:    switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
-; CHECK-NEXT:    i8 -123, label [[CASE0:%.*]]
-; CHECK-NEXT:    i8 66, label [[CASE1:%.*]]
-; CHECK-NEXT:    i8 123, label [[SUCC:%.*]]
-; CHECK-NEXT:    ]
-; CHECK:       unreachable:
-; CHECK-NEXT:    unreachable
-; CHECK:       case0:
-; CHECK-NEXT:    call void @dummy()
-; CHECK-NEXT:    [[C1_NOT:%.*]] = xor i1 [[C1]], true
-; CHECK-NEXT:    [[C2_NOT:%.*]] = xor i1 [[C2]], true
-; CHECK-NEXT:    [[BRMERGE:%.*]] = select i1 [[C1_NOT]], i1 true, i1 [[C2_NOT]]
-; CHECK-NEXT:    [[DOTMUX:%.*]] = select i1 [[C1_NOT]], i8 0, i8 3
-; CHECK-NEXT:    [[SPEC_SELECT:%.*]] = select i1 [[BRMERGE]], i8 [[DOTMUX]], i8 4
-; CHECK-NEXT:    br label [[SUCC]]
-; CHECK:       case1:
-; CHECK-NEXT:    call void @dummy()
-; CHECK-NEXT:    br label [[SUCC]]
-; CHECK:       Succ:
-; CHECK-NEXT:    [[PHI2:%.*]] = phi i8 [ 1, [[CASE1]] ], [ 2, [[ENTRY:%.*]] ], [ [[SPEC_SELECT]], [[CASE0]] ]
-; CHECK-NEXT:    ret i8 [[PHI2]]
-;
-entry:
-  switch i8 %arg, label %unreachable [
-  i8 -123, label %case0
-  i8 66, label %case1
-  i8 123, label %case2
-  ]
-
-unreachable:
-  unreachable
-
-case0:
-call void @dummy()
-  br i1 %c1, label %CommonPred, label %BB
-
-case1:
-call void @dummy()
-  br label %BB
-
-case2:
-  br label %BB
-
-CommonPred:
-  br i1 %c2, label %Succ, label %BB
-
-BB:
-  %phi1 = phi i8 [ 0, %case0 ], [1, %case1],[2, %case2],[3,%CommonPred]
-  br label %Succ
-
-Succ:
-  %phi2 = phi i8 [ %phi1, %BB ], [ 4, %CommonPred ]
-  ret i8 %phi2
-}
-
-define i8 @merge1_unfoldable_all_block(i8 noundef %arg, i1 %c1, i1 %c2) {
-; CHECK-LABEL: define i8 @merge1_unfoldable_all_block
-; CHECK-SAME: (i8 noundef [[ARG:%.*]], i1 [[C1:%.*]], i1 [[C2:%.*]]) {
-; CHECK-NEXT:  entry:
-; CHECK-NEXT:    switch i8 [[ARG]], label [[UNREACHABLE:%.*]] [
-; CHECK-NEXT:    i8 -123, label [[CASE0:%.*]]
-; CHECK-NEXT:    i8 66, label [[CASE1:%.*]]
-; CHECK-NEXT:    i8 123, label [[CASE2:%.*]]
-; CHECK-NEXT:    ]
-; CHECK:       unreachable:
-; CHECK-NEXT:    unreachable
-; CHECK:       case0:
-; CHECK-NEXT:    call void @dummy()
-; CHECK-NEXT:    br i1 [[C1]], label [[COMMONPRED:%.*]], label [[SUCC:%.*]]
-; CHECK:       case1:
-; CHECK-NEXT:    call void @dummy()
-; CHECK-NEXT:    br label [[SUCC]]
-; CHECK:       case2:
-; CHECK-NEXT:    call void @dummy()
-; CHECK-NEXT:    br label [[SUCC]]
-; CHECK:       CommonPred:
-; CHECK-NEXT:    call void @dummy()
-; CHECK-NEXT:    [[SPEC_SELECT:%.*]] = select i1 [[C2]], i8 4, i8 3
-; CHECK-NEXT:    br label [[SUCC]]
-; CHECK:       Succ:
-; CHECK-NEXT:    [[PHI2:%.*]] = phi i8 [ 0, [[CASE0]] ], [ 1, [[CASE1]] ], [ 2, [[CASE2]] ], [ [[SPEC_SELECT]], [[COMMONPRED]] ]
-; CHECK-NEXT:    ret i8 [[PHI2]]
-;
-entry:
-  switch i8 %arg, label %unreachable [
-  i8 -123, label %case0
-  i8 66, label %case1
-  i8 123, label %case2
-  ]
-
-unreachable:
-  unreachable
-
-case0:
-call void @dummy()
-  br i1 %c1, label %CommonPred, label %BB
-
-case1:
-call void @dummy()
-  br label %BB
-
-case2:
-call void @dummy()
-  br label %BB
-
-CommonPred:
-call void @dummy()
-  br i1 %c2, label %Succ, label %BB
-
-BB:
-  %phi1 = phi i8 [ 0, %case0 ], [1, %case1],[2, %case2],[3,%CommonPred]
-  br label %Succ
-
-Succ:
-  %phi2 = phi i8 [ %phi1, %BB ], [ 4, %CommonPred ]
-  ret i8 %phi2
-}
-
-declare void @dummy()
-

diff  --git a/llvm/test/Transforms/SimplifyCFG/switch-simplify-crash2.ll b/llvm/test/Transforms/SimplifyCFG/switch-simplify-crash2.ll
index 63985ec565bb9ef..eb0947397a6992b 100644
--- a/llvm/test/Transforms/SimplifyCFG/switch-simplify-crash2.ll
+++ b/llvm/test/Transforms/SimplifyCFG/switch-simplify-crash2.ll
@@ -6,9 +6,6 @@ define i8 @test() {
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    br label [[LOOP2:%.*]]
 ; CHECK:       loop2:
-; CHECK-NEXT:    [[PHI2:%.*]] = phi i8 [ 0, [[ENTRY:%.*]] ], [ [[SPEC_SELECT:%.*]], [[LOOP2]] ]
-; CHECK-NEXT:    [[COND:%.*]] = icmp eq i8 [[PHI2]], 0
-; CHECK-NEXT:    [[SPEC_SELECT]] = select i1 [[COND]], i8 0, i8 [[PHI2]]
 ; CHECK-NEXT:    br label [[LOOP2]]
 ;
 entry:


        


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