[llvm] 7fe41ac - Revert "[LV] Unconditionally branch from middle to scalar preheader if the scalar loop must execute"

Philip Reames via llvm-commits llvm-commits at lists.llvm.org
Mon Feb 8 21:09:51 PST 2021


Ben,

Thanks for the clarification.  The log does not make the fact this is an 
execution failure obvious.

No, I don't have access to a PPC machine.

I am going to need some assistance from the bot owner on this. At a 
minimum, IR for the test in question (before optimization, but on target 
platform) seems like a reasonable ask.

I strongly suspect this change is simply exposing another latent issue.  
Or at least, I've reviewed the change and don't see anything likely to 
cause runtime crashes w/o also tripping compiler asserts.

Philip


On 2/8/21 5:21 AM, Benjamin Kramer wrote:
> `execution_time` failures mean that the bot succeeded building a test
> but it failed when running it. I'm relatively certain that this is the
> same issue Adrian is seeing -- binaries segfaulting early on PPC.
>
> The bot log output isn't helpful at all for investigating why this is
> happening. Do you happen to have access to a PPC machine?
>
> On Fri, Feb 5, 2021 at 6:05 PM Philip Reames via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>> Adrian,
>>
>> I'm going to need you to provide a bit more information here. The test
>> failure in stage1 was fixed at the time you reverted this patch.  The
>> remaining failure in the bot is very unclear.  What is a execution_time
>> failure? From the log output, the "failing" run finished in 0.5 seconds,
>> whereas the previous "succeeding" run finished in 11 seconds.  Without
>> further context, I'd say that's no failure.
>>
>> I'll also note that I did not receive email from this bot.  I received
>> notice from the various other bots and fixed the ARM test issue, but
>> unless I missed it in with the others, this bot is not notifying.
>>
>> In general, I'm a fan of fast reverts, but I have to admit, this one
>> appears borderline at the moment.
>>
>> Philip
>>
>> On 2/5/21 3:53 AM, Adrian Kuegel via llvm-commits wrote:
>>> Author: Adrian Kuegel
>>> Date: 2021-02-05T12:51:03+01:00
>>> New Revision: 7fe41ac3dff2d44c3d2c31b28554fbe4a86eaa6c
>>>
>>> URL: https://github.com/llvm/llvm-project/commit/7fe41ac3dff2d44c3d2c31b28554fbe4a86eaa6c
>>> DIFF: https://github.com/llvm/llvm-project/commit/7fe41ac3dff2d44c3d2c31b28554fbe4a86eaa6c.diff
>>>
>>> LOG: Revert "[LV] Unconditionally branch from middle to scalar preheader if the scalar loop must execute"
>>>
>>> This reverts commit 3e5ce49e5371ce4feadbf97dd5c2b652d9db3d1d.
>>>
>>> Tests started failing on PPC, for example:
>>> http://lab.llvm.org:8011/#/builders/105/builds/5569
>>>
>>> Added:
>>>
>>>
>>> Modified:
>>>       llvm/lib/Transforms/Utils/LoopVersioning.cpp
>>>       llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
>>>       llvm/test/Transforms/LoopVectorize/first-order-recurrence-complex.ll
>>>       llvm/test/Transforms/LoopVectorize/interleaved-accesses.ll
>>>       llvm/test/Transforms/LoopVectorize/loop-form.ll
>>>
>>> Removed:
>>>
>>>
>>>
>>> ################################################################################
>>> diff  --git a/llvm/lib/Transforms/Utils/LoopVersioning.cpp b/llvm/lib/Transforms/Utils/LoopVersioning.cpp
>>> index 8a89158788cf..de4fb446fdf2 100644
>>> --- a/llvm/lib/Transforms/Utils/LoopVersioning.cpp
>>> +++ b/llvm/lib/Transforms/Utils/LoopVersioning.cpp
>>> @@ -44,11 +44,11 @@ LoopVersioning::LoopVersioning(const LoopAccessInfo &LAI,
>>>          AliasChecks(Checks.begin(), Checks.end()),
>>>          Preds(LAI.getPSE().getUnionPredicate()), LAI(LAI), LI(LI), DT(DT),
>>>          SE(SE) {
>>> +  assert(L->getUniqueExitBlock() && "No single exit block");
>>>    }
>>>
>>>    void LoopVersioning::versionLoop(
>>>        const SmallVectorImpl<Instruction *> &DefsUsedOutside) {
>>> -  assert(VersionedLoop->getUniqueExitBlock() && "No single exit block");
>>>      assert(VersionedLoop->isLoopSimplifyForm() &&
>>>             "Loop is not in loop-simplify form");
>>>
>>>
>>> diff  --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
>>> index 3277842edbfe..6bce0caeb36f 100644
>>> --- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
>>> +++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
>>> @@ -852,7 +852,7 @@ class InnerLoopVectorizer {
>>>      /// Middle Block between the vector and the scalar.
>>>      BasicBlock *LoopMiddleBlock;
>>>
>>> -  /// The unique ExitBlock of the scalar loop if one exists.  Note that
>>> +  /// The (unique) ExitBlock of the scalar loop.  Note that
>>>      /// there can be multiple exiting edges reaching this block.
>>>      BasicBlock *LoopExitBlock;
>>>
>>> @@ -3147,13 +3147,9 @@ void InnerLoopVectorizer::emitMinimumIterationCountCheck(Loop *L,
>>>                                   DT->getNode(Bypass)->getIDom()) &&
>>>             "TC check is expected to dominate Bypass");
>>>
>>> -  // Update dominator for Bypass & LoopExit (if needed).
>>> +  // Update dominator for Bypass & LoopExit.
>>>      DT->changeImmediateDominator(Bypass, TCCheckBlock);
>>> -  if (!Cost->requiresScalarEpilogue())
>>> -    // If there is an epilogue which must run, there's no edge from the
>>> -    // middle block to exit blocks  and thus no need to update the immediate
>>> -    // dominator of the exit blocks.
>>> -    DT->changeImmediateDominator(LoopExitBlock, TCCheckBlock);
>>> +  DT->changeImmediateDominator(LoopExitBlock, TCCheckBlock);
>>>
>>>      ReplaceInstWithInst(
>>>          TCCheckBlock->getTerminator(),
>>> @@ -3192,11 +3188,7 @@ void InnerLoopVectorizer::emitSCEVChecks(Loop *L, BasicBlock *Bypass) {
>>>      // Update dominator only if this is first RT check.
>>>      if (LoopBypassBlocks.empty()) {
>>>        DT->changeImmediateDominator(Bypass, SCEVCheckBlock);
>>> -    if (!Cost->requiresScalarEpilogue())
>>> -      // If there is an epilogue which must run, there's no edge from the
>>> -      // middle block to exit blocks  and thus no need to update the immediate
>>> -      // dominator of the exit blocks.
>>> -      DT->changeImmediateDominator(LoopExitBlock, SCEVCheckBlock);
>>> +    DT->changeImmediateDominator(LoopExitBlock, SCEVCheckBlock);
>>>      }
>>>
>>>      ReplaceInstWithInst(
>>> @@ -3252,11 +3244,7 @@ void InnerLoopVectorizer::emitMemRuntimeChecks(Loop *L, BasicBlock *Bypass) {
>>>      // Update dominator only if this is first RT check.
>>>      if (LoopBypassBlocks.empty()) {
>>>        DT->changeImmediateDominator(Bypass, MemCheckBlock);
>>> -    if (!Cost->requiresScalarEpilogue())
>>> -      // If there is an epilogue which must run, there's no edge from the
>>> -      // middle block to exit blocks  and thus no need to update the immediate
>>> -      // dominator of the exit blocks.
>>> -      DT->changeImmediateDominator(LoopExitBlock, MemCheckBlock);
>>> +    DT->changeImmediateDominator(LoopExitBlock, MemCheckBlock);
>>>      }
>>>
>>>      Instruction *FirstCheckInst;
>>> @@ -3381,10 +3369,9 @@ Value *InnerLoopVectorizer::emitTransformedIndex(
>>>    Loop *InnerLoopVectorizer::createVectorLoopSkeleton(StringRef Prefix) {
>>>      LoopScalarBody = OrigLoop->getHeader();
>>>      LoopVectorPreHeader = OrigLoop->getLoopPreheader();
>>> +  LoopExitBlock = OrigLoop->getUniqueExitBlock();
>>> +  assert(LoopExitBlock && "Must have an exit block");
>>>      assert(LoopVectorPreHeader && "Invalid loop structure");
>>> -  LoopExitBlock = OrigLoop->getUniqueExitBlock(); // may be nullptr
>>> -  assert((LoopExitBlock || Cost->requiresScalarEpilogue()) &&
>>> -         "multiple exit loop without required epilogue?");
>>>
>>>      LoopMiddleBlock =
>>>          SplitBlock(LoopVectorPreHeader, LoopVectorPreHeader->getTerminator(), DT,
>>> @@ -3393,20 +3380,12 @@ Loop *InnerLoopVectorizer::createVectorLoopSkeleton(StringRef Prefix) {
>>>          SplitBlock(LoopMiddleBlock, LoopMiddleBlock->getTerminator(), DT, LI,
>>>                     nullptr, Twine(Prefix) + "scalar.ph");
>>>
>>> +  // Set up branch from middle block to the exit and scalar preheader blocks.
>>> +  // completeLoopSkeleton will update the condition to use an iteration check,
>>> +  // if required to decide whether to execute the remainder.
>>> +  BranchInst *BrInst =
>>> +      BranchInst::Create(LoopExitBlock, LoopScalarPreHeader, Builder.getTrue());
>>>      auto *ScalarLatchTerm = OrigLoop->getLoopLatch()->getTerminator();
>>> -
>>> -  // Set up the middle block terminator.  Two cases:
>>> -  // 1) If we know that we must execute the scalar epilogue, emit an
>>> -  //    unconditional branch.
>>> -  // 2) Otherwise, we must have a single unique exit block (due to how we
>>> -  //    implement the multiple exit case).  In this case, set up a conditonal
>>> -  //    branch from the middle block to the loop scalar preheader, and the
>>> -  //    exit block.  completeLoopSkeleton will update the condition to use an
>>> -  //    iteration check, if required to decide whether to execute the remainder.
>>> -  BranchInst *BrInst = Cost->requiresScalarEpilogue() ?
>>> -    BranchInst::Create(LoopScalarPreHeader) :
>>> -    BranchInst::Create(LoopExitBlock, LoopScalarPreHeader,
>>> -                       Builder.getTrue());
>>>      BrInst->setDebugLoc(ScalarLatchTerm->getDebugLoc());
>>>      ReplaceInstWithInst(LoopMiddleBlock->getTerminator(), BrInst);
>>>
>>> @@ -3418,11 +3397,7 @@ Loop *InnerLoopVectorizer::createVectorLoopSkeleton(StringRef Prefix) {
>>>                     nullptr, nullptr, Twine(Prefix) + "vector.body");
>>>
>>>      // Update dominator for loop exit.
>>> -  if (!Cost->requiresScalarEpilogue())
>>> -    // If there is an epilogue which must run, there's no edge from the
>>> -    // middle block to exit blocks  and thus no need to update the immediate
>>> -    // dominator of the exit blocks.
>>> -    DT->changeImmediateDominator(LoopExitBlock, LoopMiddleBlock);
>>> +  DT->changeImmediateDominator(LoopExitBlock, LoopMiddleBlock);
>>>
>>>      // Create and register the new vector loop.
>>>      Loop *Lp = LI->AllocateLoop();
>>> @@ -3519,14 +3494,10 @@ BasicBlock *InnerLoopVectorizer::completeLoopSkeleton(Loop *L,
>>>      auto *ScalarLatchTerm = OrigLoop->getLoopLatch()->getTerminator();
>>>
>>>      // Add a check in the middle block to see if we have completed
>>> -  // all of the iterations in the first vector loop.  Three cases:
>>> -  // 1) If we require a scalar epilogue, there is no conditional branch as
>>> -  //    we unconditionally branch to the scalar preheader.  Do nothing.
>>> -  // 2) If (N - N%VF) == N, then we *don't* need to run the remainder.
>>> -  //    Thus if tail is to be folded, we know we don't need to run the
>>> -  //    remainder and we can use the previous value for the condition (true).
>>> -  // 3) Otherwise, construct a runtime check.
>>> -  if (!Cost->requiresScalarEpilogue() && !Cost->foldTailByMasking()) {
>>> +  // all of the iterations in the first vector loop.
>>> +  // If (N - N%VF) == N, then we *don't* need to run the remainder.
>>> +  // If tail is to be folded, we know we don't need to run the remainder.
>>> +  if (!Cost->foldTailByMasking()) {
>>>        Instruction *CmpN = CmpInst::Create(Instruction::ICmp, CmpInst::ICMP_EQ,
>>>                                            Count, VectorTripCount, "cmp.n",
>>>                                            LoopMiddleBlock->getTerminator());
>>> @@ -3590,17 +3561,17 @@ BasicBlock *InnerLoopVectorizer::createVectorizedLoopSkeleton() {
>>>      |    [  ]_|   <-- vector loop.
>>>      |     |
>>>      |     v
>>> -  \   -[ ]   <--- middle-block.
>>> -   \/   |
>>> -   /\   v
>>> -   | ->[ ]     <--- new preheader.
>>> +  |   -[ ]   <--- middle-block.
>>> +  |  /  |
>>> +  | /   v
>>> +  -|- >[ ]     <--- new preheader.
>>>       |    |
>>> - (opt)  v      <-- edge from middle to exit iff epilogue is not required.
>>> +   |    v
>>>       |   [ ] \
>>> -   |   [ ]_|   <-- old scalar loop to handle remainder (scalar epilogue).
>>> +   |   [ ]_|   <-- old scalar loop to handle remainder.
>>>        \   |
>>>         \  v
>>> -      >[ ]     <-- exit block(s).
>>> +      >[ ]     <-- exit block.
>>>       ...
>>>       */
>>>
>>> @@ -4021,18 +3992,13 @@ void InnerLoopVectorizer::fixVectorizedLoop() {
>>>      // Forget the original basic block.
>>>      PSE.getSE()->forgetLoop(OrigLoop);
>>>
>>> -  // If we inserted an edge from the middle block to the unique exit block,
>>> -  // update uses outside the loop (phis) to account for the newly inserted
>>> -  // edge.
>>> -  if (!Cost->requiresScalarEpilogue()) {
>>> -    // Fix-up external users of the induction variables.
>>> -    for (auto &Entry : Legal->getInductionVars())
>>> -      fixupIVUsers(Entry.first, Entry.second,
>>> -                   getOrCreateVectorTripCount(LI->getLoopFor(LoopVectorBody)),
>>> -                   IVEndValues[Entry.first], LoopMiddleBlock);
>>> +  // Fix-up external users of the induction variables.
>>> +  for (auto &Entry : Legal->getInductionVars())
>>> +    fixupIVUsers(Entry.first, Entry.second,
>>> +                 getOrCreateVectorTripCount(LI->getLoopFor(LoopVectorBody)),
>>> +                 IVEndValues[Entry.first], LoopMiddleBlock);
>>>
>>> -    fixLCSSAPHIs();
>>> -  }
>>> +  fixLCSSAPHIs();
>>>      for (Instruction *PI : PredicatedInstructions)
>>>        sinkScalarOperands(&*PI);
>>>
>>> @@ -4250,13 +4216,12 @@ void InnerLoopVectorizer::fixFirstOrderRecurrence(PHINode *Phi) {
>>>      // recurrence in the exit block, and then add an edge for the middle block.
>>>      // Note that LCSSA does not imply single entry when the original scalar loop
>>>      // had multiple exiting edges (as we always run the last iteration in the
>>> -  // scalar epilogue); in that case, there is no edge from middle to exit and
>>> -  // and thus no phis which needed updated.
>>> -  if (!Cost->requiresScalarEpilogue())
>>> -    for (PHINode &LCSSAPhi : LoopExitBlock->phis())
>>> -      if (any_of(LCSSAPhi.incoming_values(),
>>> -                 [Phi](Value *V) { return V == Phi; }))
>>> -        LCSSAPhi.addIncoming(ExtractForPhiUsedOutsideLoop, LoopMiddleBlock);
>>> +  // scalar epilogue); in that case, the exiting path through middle will be
>>> +  // dynamically dead and the value picked for the phi doesn't matter.
>>> +  for (PHINode &LCSSAPhi : LoopExitBlock->phis())
>>> +    if (any_of(LCSSAPhi.incoming_values(),
>>> +               [Phi](Value *V) { return V == Phi; }))
>>> +      LCSSAPhi.addIncoming(ExtractForPhiUsedOutsideLoop, LoopMiddleBlock);
>>>    }
>>>
>>>    void InnerLoopVectorizer::fixReduction(PHINode *Phi) {
>>> @@ -4421,11 +4386,10 @@ void InnerLoopVectorizer::fixReduction(PHINode *Phi) {
>>>      // We know that the loop is in LCSSA form. We need to update the PHI nodes
>>>      // in the exit blocks.  See comment on analogous loop in
>>>      // fixFirstOrderRecurrence for a more complete explaination of the logic.
>>> -  if (!Cost->requiresScalarEpilogue())
>>> -    for (PHINode &LCSSAPhi : LoopExitBlock->phis())
>>> -      if (any_of(LCSSAPhi.incoming_values(),
>>> -                 [LoopExitInst](Value *V) { return V == LoopExitInst; }))
>>> -        LCSSAPhi.addIncoming(ReducedPartRdx, LoopMiddleBlock);
>>> +  for (PHINode &LCSSAPhi : LoopExitBlock->phis())
>>> +    if (any_of(LCSSAPhi.incoming_values(),
>>> +               [LoopExitInst](Value *V) { return V == LoopExitInst; }))
>>> +      LCSSAPhi.addIncoming(ReducedPartRdx, LoopMiddleBlock);
>>>
>>>      // Fix the scalar loop reduction variable with the incoming reduction sum
>>>      // from the vector body and from the backedge value.
>>> @@ -8074,11 +8038,7 @@ BasicBlock *EpilogueVectorizerMainLoop::emitMinimumIterationCountCheck(
>>>
>>>        // Update dominator for Bypass & LoopExit.
>>>        DT->changeImmediateDominator(Bypass, TCCheckBlock);
>>> -    if (!Cost->requiresScalarEpilogue())
>>> -      // For loops with multiple exits, there's no edge from the middle block
>>> -      // to exit blocks (as the epilogue must run) and thus no need to update
>>> -      // the immediate dominator of the exit blocks.
>>> -      DT->changeImmediateDominator(LoopExitBlock, TCCheckBlock);
>>> +    DT->changeImmediateDominator(LoopExitBlock, TCCheckBlock);
>>>
>>>        LoopBypassBlocks.push_back(TCCheckBlock);
>>>
>>> @@ -8142,12 +8102,7 @@ EpilogueVectorizerEpilogueLoop::createEpilogueVectorizedLoopSkeleton() {
>>>
>>>      DT->changeImmediateDominator(LoopScalarPreHeader,
>>>                                   EPI.EpilogueIterationCountCheck);
>>> -  if (!Cost->requiresScalarEpilogue())
>>> -    // If there is an epilogue which must run, there's no edge from the
>>> -    // middle block to exit blocks  and thus no need to update the immediate
>>> -    // dominator of the exit blocks.
>>> -    DT->changeImmediateDominator(LoopExitBlock,
>>> -                                 EPI.EpilogueIterationCountCheck);
>>> +  DT->changeImmediateDominator(LoopExitBlock, EPI.EpilogueIterationCountCheck);
>>>
>>>      // Keep track of bypass blocks, as they feed start values to the induction
>>>      // phis in the scalar loop preheader.
>>>
>>> diff  --git a/llvm/test/Transforms/LoopVectorize/first-order-recurrence-complex.ll b/llvm/test/Transforms/LoopVectorize/first-order-recurrence-complex.ll
>>> index ec280bf5d5e4..7d4a3c5c9935 100644
>>> --- a/llvm/test/Transforms/LoopVectorize/first-order-recurrence-complex.ll
>>> +++ b/llvm/test/Transforms/LoopVectorize/first-order-recurrence-complex.ll
>>> @@ -471,9 +471,10 @@ define i16 @multiple_exit(i16* %p, i32 %n) {
>>>    ; CHECK-NEXT:    [[TMP15:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
>>>    ; CHECK-NEXT:    br i1 [[TMP15]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], [[LOOP6:!llvm.loop !.*]]
>>>    ; CHECK:       middle.block:
>>> +; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[TMP2]], [[N_VEC]]
>>>    ; CHECK-NEXT:    [[VECTOR_RECUR_EXTRACT:%.*]] = extractelement <4 x i16> [[WIDE_LOAD]], i32 3
>>>    ; CHECK-NEXT:    [[VECTOR_RECUR_EXTRACT_FOR_PHI:%.*]] = extractelement <4 x i16> [[WIDE_LOAD]], i32 2
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    br i1 [[CMP_N]], label [[IF_END:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[SCALAR_RECUR_INIT:%.*]] = phi i16 [ 0, [[ENTRY:%.*]] ], [ [[VECTOR_RECUR_EXTRACT]], [[MIDDLE_BLOCK]] ]
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i32 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY]] ]
>>> @@ -485,14 +486,14 @@ define i16 @multiple_exit(i16* %p, i32 %n) {
>>>    ; CHECK-NEXT:    [[B:%.*]] = getelementptr inbounds i16, i16* [[P]], i64 [[IPROM]]
>>>    ; CHECK-NEXT:    [[REC_NEXT]] = load i16, i16* [[B]], align 2
>>>    ; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[I]], [[N]]
>>> -; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[IF_END:%.*]]
>>> +; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[IF_END]]
>>>    ; CHECK:       for.body:
>>>    ; CHECK-NEXT:    store i16 [[SCALAR_RECUR]], i16* [[B]], align 4
>>>    ; CHECK-NEXT:    [[INC]] = add nsw i32 [[I]], 1
>>>    ; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i32 [[I]], 2096
>>>    ; CHECK-NEXT:    br i1 [[CMP2]], label [[FOR_COND]], label [[IF_END]], [[LOOP7:!llvm.loop !.*]]
>>>    ; CHECK:       if.end:
>>> -; CHECK-NEXT:    [[REC_LCSSA:%.*]] = phi i16 [ [[SCALAR_RECUR]], [[FOR_BODY]] ], [ [[SCALAR_RECUR]], [[FOR_COND]] ]
>>> +; CHECK-NEXT:    [[REC_LCSSA:%.*]] = phi i16 [ [[SCALAR_RECUR]], [[FOR_BODY]] ], [ [[SCALAR_RECUR]], [[FOR_COND]] ], [ [[VECTOR_RECUR_EXTRACT_FOR_PHI]], [[MIDDLE_BLOCK]] ]
>>>    ; CHECK-NEXT:    ret i16 [[REC_LCSSA]]
>>>    ;
>>>    entry:
>>> @@ -557,9 +558,10 @@ define i16 @multiple_exit2(i16* %p, i32 %n) {
>>>    ; CHECK-NEXT:    [[TMP15:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
>>>    ; CHECK-NEXT:    br i1 [[TMP15]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], [[LOOP8:!llvm.loop !.*]]
>>>    ; CHECK:       middle.block:
>>> +; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[TMP2]], [[N_VEC]]
>>>    ; CHECK-NEXT:    [[VECTOR_RECUR_EXTRACT:%.*]] = extractelement <4 x i16> [[WIDE_LOAD]], i32 3
>>>    ; CHECK-NEXT:    [[VECTOR_RECUR_EXTRACT_FOR_PHI:%.*]] = extractelement <4 x i16> [[WIDE_LOAD]], i32 2
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    br i1 [[CMP_N]], label [[IF_END:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[SCALAR_RECUR_INIT:%.*]] = phi i16 [ 0, [[ENTRY:%.*]] ], [ [[VECTOR_RECUR_EXTRACT]], [[MIDDLE_BLOCK]] ]
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i32 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY]] ]
>>> @@ -571,14 +573,14 @@ define i16 @multiple_exit2(i16* %p, i32 %n) {
>>>    ; CHECK-NEXT:    [[B:%.*]] = getelementptr inbounds i16, i16* [[P]], i64 [[IPROM]]
>>>    ; CHECK-NEXT:    [[REC_NEXT]] = load i16, i16* [[B]], align 2
>>>    ; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[I]], [[N]]
>>> -; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[IF_END:%.*]]
>>> +; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[IF_END]]
>>>    ; CHECK:       for.body:
>>>    ; CHECK-NEXT:    store i16 [[SCALAR_RECUR]], i16* [[B]], align 4
>>>    ; CHECK-NEXT:    [[INC]] = add nsw i32 [[I]], 1
>>>    ; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i32 [[I]], 2096
>>>    ; CHECK-NEXT:    br i1 [[CMP2]], label [[FOR_COND]], label [[IF_END]], [[LOOP9:!llvm.loop !.*]]
>>>    ; CHECK:       if.end:
>>> -; CHECK-NEXT:    [[REC_LCSSA:%.*]] = phi i16 [ [[SCALAR_RECUR]], [[FOR_COND]] ], [ 10, [[FOR_BODY]] ]
>>> +; CHECK-NEXT:    [[REC_LCSSA:%.*]] = phi i16 [ [[SCALAR_RECUR]], [[FOR_COND]] ], [ 10, [[FOR_BODY]] ], [ [[VECTOR_RECUR_EXTRACT_FOR_PHI]], [[MIDDLE_BLOCK]] ]
>>>    ; CHECK-NEXT:    ret i16 [[REC_LCSSA]]
>>>    ;
>>>    entry:
>>>
>>> diff  --git a/llvm/test/Transforms/LoopVectorize/interleaved-accesses.ll b/llvm/test/Transforms/LoopVectorize/interleaved-accesses.ll
>>> index f0ba677348ab..0d4bdf0ecac3 100644
>>> --- a/llvm/test/Transforms/LoopVectorize/interleaved-accesses.ll
>>> +++ b/llvm/test/Transforms/LoopVectorize/interleaved-accesses.ll
>>> @@ -447,7 +447,7 @@ define void @even_load_static_tc(i32* noalias nocapture readonly %A, i32* noalia
>>>    ; CHECK-NEXT:    [[TMP6:%.*]] = icmp eq i64 [[INDEX_NEXT]], 508
>>>    ; CHECK-NEXT:    br i1 [[TMP6]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], [[LOOP12:!llvm.loop !.*]]
>>>    ; CHECK:       middle.block:
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    br i1 false, label [[FOR_COND_CLEANUP:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ 1016, [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
>>>    ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
>>> @@ -463,7 +463,7 @@ define void @even_load_static_tc(i32* noalias nocapture readonly %A, i32* noalia
>>>    ; CHECK-NEXT:    store i32 [[MUL]], i32* [[ARRAYIDX2]], align 4
>>>    ; CHECK-NEXT:    [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 2
>>>    ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i64 [[INDVARS_IV]], 1022
>>> -; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_COND_CLEANUP:%.*]], [[LOOP13:!llvm.loop !.*]]
>>> +; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_COND_CLEANUP]], [[LOOP13:!llvm.loop !.*]]
>>>    ;
>>>    entry:
>>>      br label %for.body
>>> @@ -528,7 +528,7 @@ define void @even_load_dynamic_tc(i32* noalias nocapture readonly %A, i32* noali
>>>    ; CHECK-NEXT:    [[TMP12:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
>>>    ; CHECK-NEXT:    br i1 [[TMP12]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], [[LOOP14:!llvm.loop !.*]]
>>>    ; CHECK:       middle.block:
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    br i1 false, label [[FOR_COND_CLEANUP:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ [[IND_END]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
>>>    ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
>>> @@ -544,7 +544,7 @@ define void @even_load_dynamic_tc(i32* noalias nocapture readonly %A, i32* noali
>>>    ; CHECK-NEXT:    store i32 [[MUL]], i32* [[ARRAYIDX2]], align 4
>>>    ; CHECK-NEXT:    [[INDVARS_IV_NEXT]] = add nuw nsw i64 [[INDVARS_IV]], 2
>>>    ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i64 [[INDVARS_IV_NEXT]], [[N]]
>>> -; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_COND_CLEANUP:%.*]], [[LOOP15:!llvm.loop !.*]]
>>> +; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_COND_CLEANUP]], [[LOOP15:!llvm.loop !.*]]
>>>    ;
>>>    entry:
>>>      br label %for.body
>>> @@ -973,7 +973,7 @@ define void @PR27626_0(%pair.i32 *%p, i32 %z, i64 %n) {
>>>    ; CHECK-NEXT:    [[TMP19:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
>>>    ; CHECK-NEXT:    br i1 [[TMP19]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], [[LOOP24:!llvm.loop !.*]]
>>>    ; CHECK:       middle.block:
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    br i1 false, label [[FOR_END:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
>>>    ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
>>> @@ -985,7 +985,7 @@ define void @PR27626_0(%pair.i32 *%p, i32 %z, i64 %n) {
>>>    ; CHECK-NEXT:    store i32 [[Z]], i32* [[P_I_Y]], align 4
>>>    ; CHECK-NEXT:    [[I_NEXT]] = add nuw nsw i64 [[I]], 1
>>>    ; CHECK-NEXT:    [[COND:%.*]] = icmp slt i64 [[I_NEXT]], [[N]]
>>> -; CHECK-NEXT:    br i1 [[COND]], label [[FOR_BODY]], label [[FOR_END:%.*]], [[LOOP25:!llvm.loop !.*]]
>>> +; CHECK-NEXT:    br i1 [[COND]], label [[FOR_BODY]], label [[FOR_END]], [[LOOP25:!llvm.loop !.*]]
>>>    ; CHECK:       for.end:
>>>    ; CHECK-NEXT:    ret void
>>>    ;
>>> @@ -1066,7 +1066,7 @@ define i32 @PR27626_1(%pair.i32 *%p, i64 %n) {
>>>    ; CHECK-NEXT:    [[RDX_SHUF3:%.*]] = shufflevector <4 x i32> [[BIN_RDX]], <4 x i32> poison, <4 x i32> <i32 1, i32 undef, i32 undef, i32 undef>
>>>    ; CHECK-NEXT:    [[BIN_RDX4:%.*]] = add <4 x i32> [[BIN_RDX]], [[RDX_SHUF3]]
>>>    ; CHECK-NEXT:    [[TMP19:%.*]] = extractelement <4 x i32> [[BIN_RDX4]], i32 0
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    br i1 false, label [[FOR_END:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
>>>    ; CHECK-NEXT:    [[BC_MERGE_RDX:%.*]] = phi i32 [ [[TMP19]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY]] ]
>>> @@ -1081,9 +1081,10 @@ define i32 @PR27626_1(%pair.i32 *%p, i64 %n) {
>>>    ; CHECK-NEXT:    [[TMP21]] = add nsw i32 [[TMP20]], [[S]]
>>>    ; CHECK-NEXT:    [[I_NEXT]] = add nuw nsw i64 [[I]], 1
>>>    ; CHECK-NEXT:    [[COND:%.*]] = icmp slt i64 [[I_NEXT]], [[N]]
>>> -; CHECK-NEXT:    br i1 [[COND]], label [[FOR_BODY]], label [[FOR_END:%.*]], [[LOOP27:!llvm.loop !.*]]
>>> +; CHECK-NEXT:    br i1 [[COND]], label [[FOR_BODY]], label [[FOR_END]], [[LOOP27:!llvm.loop !.*]]
>>>    ; CHECK:       for.end:
>>> -; CHECK-NEXT:    ret i32 [[TMP21]]
>>> +; CHECK-NEXT:    [[TMP22:%.*]] = phi i32 [ [[TMP21]], [[FOR_BODY]] ], [ [[TMP19]], [[MIDDLE_BLOCK]] ]
>>> +; CHECK-NEXT:    ret i32 [[TMP22]]
>>>    ;
>>>    entry:
>>>      br label %for.body
>>> @@ -1162,7 +1163,7 @@ define void @PR27626_2(%pair.i32 *%p, i64 %n, i32 %z) {
>>>    ; CHECK-NEXT:    [[TMP20:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
>>>    ; CHECK-NEXT:    br i1 [[TMP20]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], [[LOOP28:!llvm.loop !.*]]
>>>    ; CHECK:       middle.block:
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    br i1 false, label [[FOR_END:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
>>>    ; CHECK-NEXT:    br label [[FOR_BODY:%.*]]
>>> @@ -1176,7 +1177,7 @@ define void @PR27626_2(%pair.i32 *%p, i64 %n, i32 %z) {
>>>    ; CHECK-NEXT:    store i32 [[TMP21]], i32* [[P_I_Y]], align 4
>>>    ; CHECK-NEXT:    [[I_NEXT]] = add nuw nsw i64 [[I]], 1
>>>    ; CHECK-NEXT:    [[COND:%.*]] = icmp slt i64 [[I_NEXT]], [[N]]
>>> -; CHECK-NEXT:    br i1 [[COND]], label [[FOR_BODY]], label [[FOR_END:%.*]], [[LOOP29:!llvm.loop !.*]]
>>> +; CHECK-NEXT:    br i1 [[COND]], label [[FOR_BODY]], label [[FOR_END]], [[LOOP29:!llvm.loop !.*]]
>>>    ; CHECK:       for.end:
>>>    ; CHECK-NEXT:    ret void
>>>    ;
>>> @@ -1263,7 +1264,7 @@ define i32 @PR27626_3(%pair.i32 *%p, i64 %n, i32 %z) {
>>>    ; CHECK-NEXT:    [[RDX_SHUF3:%.*]] = shufflevector <4 x i32> [[BIN_RDX]], <4 x i32> poison, <4 x i32> <i32 1, i32 undef, i32 undef, i32 undef>
>>>    ; CHECK-NEXT:    [[BIN_RDX4:%.*]] = add <4 x i32> [[BIN_RDX]], [[RDX_SHUF3]]
>>>    ; CHECK-NEXT:    [[TMP22:%.*]] = extractelement <4 x i32> [[BIN_RDX4]], i32 0
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    br i1 false, label [[FOR_END:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
>>>    ; CHECK-NEXT:    [[BC_MERGE_RDX:%.*]] = phi i32 [ [[TMP22]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY]] ]
>>> @@ -1281,9 +1282,10 @@ define i32 @PR27626_3(%pair.i32 *%p, i64 %n, i32 %z) {
>>>    ; CHECK-NEXT:    [[TMP25]] = add nsw i32 [[TMP24]], [[S]]
>>>    ; CHECK-NEXT:    [[I_NEXT]] = add nuw nsw i64 [[I]], 1
>>>    ; CHECK-NEXT:    [[COND:%.*]] = icmp slt i64 [[I_NEXT]], [[N]]
>>> -; CHECK-NEXT:    br i1 [[COND]], label [[FOR_BODY]], label [[FOR_END:%.*]], [[LOOP31:!llvm.loop !.*]]
>>> +; CHECK-NEXT:    br i1 [[COND]], label [[FOR_BODY]], label [[FOR_END]], [[LOOP31:!llvm.loop !.*]]
>>>    ; CHECK:       for.end:
>>> -; CHECK-NEXT:    ret i32 [[TMP25]]
>>> +; CHECK-NEXT:    [[TMP26:%.*]] = phi i32 [ [[TMP25]], [[FOR_BODY]] ], [ [[TMP22]], [[MIDDLE_BLOCK]] ]
>>> +; CHECK-NEXT:    ret i32 [[TMP26]]
>>>    ;
>>>    entry:
>>>      br label %for.body
>>>
>>> diff  --git a/llvm/test/Transforms/LoopVectorize/loop-form.ll b/llvm/test/Transforms/LoopVectorize/loop-form.ll
>>> index f32002fae2b6..91780789088b 100644
>>> --- a/llvm/test/Transforms/LoopVectorize/loop-form.ll
>>> +++ b/llvm/test/Transforms/LoopVectorize/loop-form.ll
>>> @@ -146,14 +146,15 @@ define void @early_exit(i16* %p, i32 %n) {
>>>    ; CHECK-NEXT:    [[TMP10:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
>>>    ; CHECK-NEXT:    br i1 [[TMP10]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], [[LOOP4:!llvm.loop !.*]]
>>>    ; CHECK:       middle.block:
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[TMP1]], [[N_VEC]]
>>> +; CHECK-NEXT:    br i1 [[CMP_N]], label [[IF_END:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i32 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
>>>    ; CHECK-NEXT:    br label [[FOR_COND:%.*]]
>>>    ; CHECK:       for.cond:
>>>    ; CHECK-NEXT:    [[I:%.*]] = phi i32 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[INC:%.*]], [[FOR_BODY:%.*]] ]
>>>    ; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[I]], [[N]]
>>> -; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[IF_END:%.*]]
>>> +; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[IF_END]]
>>>    ; CHECK:       for.body:
>>>    ; CHECK-NEXT:    [[IPROM:%.*]] = sext i32 [[I]] to i64
>>>    ; CHECK-NEXT:    [[B:%.*]] = getelementptr inbounds i16, i16* [[P]], i64 [[IPROM]]
>>> @@ -285,14 +286,15 @@ define void @multiple_unique_exit(i16* %p, i32 %n) {
>>>    ; CHECK-NEXT:    [[TMP11:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
>>>    ; CHECK-NEXT:    br i1 [[TMP11]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], [[LOOP6:!llvm.loop !.*]]
>>>    ; CHECK:       middle.block:
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[TMP2]], [[N_VEC]]
>>> +; CHECK-NEXT:    br i1 [[CMP_N]], label [[IF_END:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i32 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
>>>    ; CHECK-NEXT:    br label [[FOR_COND:%.*]]
>>>    ; CHECK:       for.cond:
>>>    ; CHECK-NEXT:    [[I:%.*]] = phi i32 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[INC:%.*]], [[FOR_BODY:%.*]] ]
>>>    ; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[I]], [[N]]
>>> -; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[IF_END:%.*]]
>>> +; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[IF_END]]
>>>    ; CHECK:       for.body:
>>>    ; CHECK-NEXT:    [[IPROM:%.*]] = sext i32 [[I]] to i64
>>>    ; CHECK-NEXT:    [[B:%.*]] = getelementptr inbounds i16, i16* [[P]], i64 [[IPROM]]
>>> @@ -372,14 +374,17 @@ define i32 @multiple_unique_exit2(i16* %p, i32 %n) {
>>>    ; CHECK-NEXT:    [[TMP11:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
>>>    ; CHECK-NEXT:    br i1 [[TMP11]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], [[LOOP8:!llvm.loop !.*]]
>>>    ; CHECK:       middle.block:
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[TMP2]], [[N_VEC]]
>>> +; CHECK-NEXT:    [[IND_ESCAPE:%.*]] = sub i32 [[N_VEC]], 1
>>> +; CHECK-NEXT:    [[IND_ESCAPE1:%.*]] = sub i32 [[N_VEC]], 1
>>> +; CHECK-NEXT:    br i1 [[CMP_N]], label [[IF_END:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i32 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
>>>    ; CHECK-NEXT:    br label [[FOR_COND:%.*]]
>>>    ; CHECK:       for.cond:
>>>    ; CHECK-NEXT:    [[I:%.*]] = phi i32 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[INC:%.*]], [[FOR_BODY:%.*]] ]
>>>    ; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[I]], [[N]]
>>> -; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[IF_END:%.*]]
>>> +; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[IF_END]]
>>>    ; CHECK:       for.body:
>>>    ; CHECK-NEXT:    [[IPROM:%.*]] = sext i32 [[I]] to i64
>>>    ; CHECK-NEXT:    [[B:%.*]] = getelementptr inbounds i16, i16* [[P]], i64 [[IPROM]]
>>> @@ -388,7 +393,7 @@ define i32 @multiple_unique_exit2(i16* %p, i32 %n) {
>>>    ; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i32 [[I]], 2096
>>>    ; CHECK-NEXT:    br i1 [[CMP2]], label [[FOR_COND]], label [[IF_END]], [[LOOP9:!llvm.loop !.*]]
>>>    ; CHECK:       if.end:
>>> -; CHECK-NEXT:    [[I_LCSSA:%.*]] = phi i32 [ [[I]], [[FOR_BODY]] ], [ [[I]], [[FOR_COND]] ]
>>> +; CHECK-NEXT:    [[I_LCSSA:%.*]] = phi i32 [ [[I]], [[FOR_BODY]] ], [ [[I]], [[FOR_COND]] ], [ [[IND_ESCAPE1]], [[MIDDLE_BLOCK]] ]
>>>    ; CHECK-NEXT:    ret i32 [[I_LCSSA]]
>>>    ;
>>>    ; TAILFOLD-LABEL: @multiple_unique_exit2(
>>> @@ -461,14 +466,15 @@ define i32 @multiple_unique_exit3(i16* %p, i32 %n) {
>>>    ; CHECK-NEXT:    [[TMP11:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
>>>    ; CHECK-NEXT:    br i1 [[TMP11]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], [[LOOP10:!llvm.loop !.*]]
>>>    ; CHECK:       middle.block:
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i32 [[TMP2]], [[N_VEC]]
>>> +; CHECK-NEXT:    br i1 [[CMP_N]], label [[IF_END:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i32 [ [[N_VEC]], [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
>>>    ; CHECK-NEXT:    br label [[FOR_COND:%.*]]
>>>    ; CHECK:       for.cond:
>>>    ; CHECK-NEXT:    [[I:%.*]] = phi i32 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[INC:%.*]], [[FOR_BODY:%.*]] ]
>>>    ; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[I]], [[N]]
>>> -; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[IF_END:%.*]]
>>> +; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[IF_END]]
>>>    ; CHECK:       for.body:
>>>    ; CHECK-NEXT:    [[IPROM:%.*]] = sext i32 [[I]] to i64
>>>    ; CHECK-NEXT:    [[B:%.*]] = getelementptr inbounds i16, i16* [[P]], i64 [[IPROM]]
>>> @@ -477,7 +483,7 @@ define i32 @multiple_unique_exit3(i16* %p, i32 %n) {
>>>    ; CHECK-NEXT:    [[CMP2:%.*]] = icmp slt i32 [[I]], 2096
>>>    ; CHECK-NEXT:    br i1 [[CMP2]], label [[FOR_COND]], label [[IF_END]], [[LOOP11:!llvm.loop !.*]]
>>>    ; CHECK:       if.end:
>>> -; CHECK-NEXT:    [[EXIT:%.*]] = phi i32 [ 0, [[FOR_COND]] ], [ 1, [[FOR_BODY]] ]
>>> +; CHECK-NEXT:    [[EXIT:%.*]] = phi i32 [ 0, [[FOR_COND]] ], [ 1, [[FOR_BODY]] ], [ 0, [[MIDDLE_BLOCK]] ]
>>>    ; CHECK-NEXT:    ret i32 [[EXIT]]
>>>    ;
>>>    ; TAILFOLD-LABEL: @multiple_unique_exit3(
>>> @@ -994,7 +1000,8 @@ define void @scalar_predication(float* %addr) {
>>>    ; CHECK-NEXT:    [[TMP10:%.*]] = icmp eq i64 [[INDEX_NEXT]], 200
>>>    ; CHECK-NEXT:    br i1 [[TMP10]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], [[LOOP12:!llvm.loop !.*]]
>>>    ; CHECK:       middle.block:
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i64 201, 200
>>> +; CHECK-NEXT:    br i1 [[CMP_N]], label [[EXIT:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ 200, [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
>>>    ; CHECK-NEXT:    br label [[LOOP_HEADER:%.*]]
>>> @@ -1002,7 +1009,7 @@ define void @scalar_predication(float* %addr) {
>>>    ; CHECK-NEXT:    [[IV:%.*]] = phi i64 [ [[BC_RESUME_VAL]], [[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], [[LOOP_LATCH:%.*]] ]
>>>    ; CHECK-NEXT:    [[GEP:%.*]] = getelementptr float, float* [[ADDR]], i64 [[IV]]
>>>    ; CHECK-NEXT:    [[EXITCOND_NOT:%.*]] = icmp eq i64 [[IV]], 200
>>> -; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label [[EXIT:%.*]], label [[LOOP_BODY:%.*]]
>>> +; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label [[EXIT]], label [[LOOP_BODY:%.*]]
>>>    ; CHECK:       loop.body:
>>>    ; CHECK-NEXT:    [[TMP11:%.*]] = load float, float* [[GEP]], align 4
>>>    ; CHECK-NEXT:    [[PRED:%.*]] = fcmp oeq float [[TMP11]], 0.000000e+00
>>> @@ -1088,7 +1095,8 @@ define i32 @me_reduction(i32* %addr) {
>>>    ; CHECK-NEXT:    [[RDX_SHUF:%.*]] = shufflevector <2 x i32> [[TMP5]], <2 x i32> poison, <2 x i32> <i32 1, i32 undef>
>>>    ; CHECK-NEXT:    [[BIN_RDX:%.*]] = add <2 x i32> [[TMP5]], [[RDX_SHUF]]
>>>    ; CHECK-NEXT:    [[TMP7:%.*]] = extractelement <2 x i32> [[BIN_RDX]], i32 0
>>> -; CHECK-NEXT:    br label [[SCALAR_PH]]
>>> +; CHECK-NEXT:    [[CMP_N:%.*]] = icmp eq i64 201, 200
>>> +; CHECK-NEXT:    br i1 [[CMP_N]], label [[EXIT:%.*]], label [[SCALAR_PH]]
>>>    ; CHECK:       scalar.ph:
>>>    ; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i64 [ 200, [[MIDDLE_BLOCK]] ], [ 0, [[ENTRY:%.*]] ]
>>>    ; CHECK-NEXT:    [[BC_MERGE_RDX:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[TMP7]], [[MIDDLE_BLOCK]] ]
>>> @@ -1098,7 +1106,7 @@ define i32 @me_reduction(i32* %addr) {
>>>    ; CHECK-NEXT:    [[ACCUM:%.*]] = phi i32 [ [[BC_MERGE_RDX]], [[SCALAR_PH]] ], [ [[ACCUM_NEXT:%.*]], [[LOOP_LATCH]] ]
>>>    ; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i32, i32* [[ADDR]], i64 [[IV]]
>>>    ; CHECK-NEXT:    [[EXITCOND_NOT:%.*]] = icmp eq i64 [[IV]], 200
>>> -; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label [[EXIT:%.*]], label [[LOOP_LATCH]]
>>> +; CHECK-NEXT:    br i1 [[EXITCOND_NOT]], label [[EXIT]], label [[LOOP_LATCH]]
>>>    ; CHECK:       loop.latch:
>>>    ; CHECK-NEXT:    [[TMP8:%.*]] = load i32, i32* [[GEP]], align 4
>>>    ; CHECK-NEXT:    [[ACCUM_NEXT]] = add i32 [[ACCUM]], [[TMP8]]
>>> @@ -1106,7 +1114,7 @@ define i32 @me_reduction(i32* %addr) {
>>>    ; CHECK-NEXT:    [[EXITCOND2_NOT:%.*]] = icmp eq i64 [[IV]], 400
>>>    ; CHECK-NEXT:    br i1 [[EXITCOND2_NOT]], label [[EXIT]], label [[LOOP_HEADER]], [[LOOP15:!llvm.loop !.*]]
>>>    ; CHECK:       exit:
>>> -; CHECK-NEXT:    [[LCSSA:%.*]] = phi i32 [ 0, [[LOOP_HEADER]] ], [ [[ACCUM_NEXT]], [[LOOP_LATCH]] ]
>>> +; CHECK-NEXT:    [[LCSSA:%.*]] = phi i32 [ 0, [[LOOP_HEADER]] ], [ [[ACCUM_NEXT]], [[LOOP_LATCH]] ], [ [[TMP7]], [[MIDDLE_BLOCK]] ]
>>>    ; CHECK-NEXT:    ret i32 [[LCSSA]]
>>>    ;
>>>    ; TAILFOLD-LABEL: @me_reduction(
>>>
>>>
>>>
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