[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
Wed May 5 13:01:56 PDT 2021
FYI, I'm going to try recommitting this without changes in a day or so.
I never heard back from a PPC bot owner, and I don't have enough
information to really debug anything from the builtbot log. I did run
across a latent issue which this patch may very well have exposed at
much higher frequency; the previous patch in this series (which is much
more restrictive) does appear to have increased frequency. That was
worked around in 80e80250. My educated guess is that same issue
triggered the miscompile seen on the ppc bot, but that is more of a
guess than I'd really prefer.
I'm going to submit this during off hours, and watch the bots fairly
closely after submit. Hopefully this either cycles clean or I get a
better clue as to what the root issue is.
Philip
On 2/8/21 9:09 PM, Philip Reames via llvm-commits wrote:
> 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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