Unverified Commit 4fe94d03 authored by Roman Lebedev's avatar Roman Lebedev
Browse files

[LoopUnroll] countToEliminateCompares(): fix handling of [in]equality predicates (PR43840) 

Summary:
I believe this bisects to https://reviews.llvm.org/D44983
(`[LoopUnroll] Only peel if a predicate becomes known in the loop body.`)

While that revision did contain tests that showed arguably-subpar peeling
for [in]equality predicates that [not] happen in the middle of the loop,
it also disabled peeling for the *first* loop iteration,
because latch would be canonicalized to [in]equality comparison..

That was intentional as per https://reviews.llvm.org/D44983#1059583.
I'm not 100% sure that i'm using correct checks here,
but this fix appears to be going in the right direction..

Let me know if i'm missing some checks here..

Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=43840 | PR43840 ]].

Reviewers: fhahn, mkazantsev, efriedma

Reviewed By: fhahn

Subscribers: xbolva00, hiraditya, zzheng, llvm-commits, fhahn

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D69617
parent 432a12c8

llvm/lib/Transforms/Utils/LoopUnrollPeel.cpp

+38 −16
Original line number Diff line number Diff line
@@ -212,14 +212,11 @@ static unsigned countToEliminateCompares(Loop &L, unsigned MaxPeelCount, 
    const SCEVAddRecExpr *LeftAR = cast<SCEVAddRecExpr>(LeftSCEV);



    // Avoid huge SCEV computations in the loop below, make sure we only

    // consider AddRecs of the loop we are trying to peel and avoid

    // non-monotonic predicates, as we will not be able to simplify the loop

    // body.

    // FIXME: For the non-monotonic predicates ICMP_EQ and ICMP_NE we can

    //        simplify the loop, if we peel 1 additional iteration, if there

    //        is no wrapping.

    // consider AddRecs of the loop we are trying to peel.

    if (!LeftAR->isAffine() || LeftAR->getLoop() != &L)

      continue;

    bool Increasing;

    if (!LeftAR->isAffine() || LeftAR->getLoop() != &L ||

    if (!(ICmpInst::isEquality(Pred) && LeftAR->hasNoSelfWrap()) &&

        !SE.isMonotonicPredicate(LeftAR, Pred, Increasing))

      continue;

    (void)Increasing;
@@ -238,18 +235,43 @@ static unsigned countToEliminateCompares(Loop &L, unsigned MaxPeelCount, 
      Pred = ICmpInst::getInversePredicate(Pred);



    const SCEV *Step = LeftAR->getStepRecurrence(SE);

    while (NewPeelCount < MaxPeelCount &&

           SE.isKnownPredicate(Pred, IterVal, RightSCEV)) {

      IterVal = SE.getAddExpr(IterVal, Step);

    const SCEV *NextIterVal = SE.getAddExpr(IterVal, Step);

    auto PeelOneMoreIteration = [&IterVal, &NextIterVal, &SE, Step,

                                 &NewPeelCount]() {

      IterVal = NextIterVal;

      NextIterVal = SE.getAddExpr(IterVal, Step);

      NewPeelCount++;

    }

    };



    auto CanPeelOneMoreIteration = [&NewPeelCount, &MaxPeelCount]() {

      return NewPeelCount < MaxPeelCount;

    };



    while (CanPeelOneMoreIteration() &&

           SE.isKnownPredicate(Pred, IterVal, RightSCEV))

      PeelOneMoreIteration();



    // Only peel the loop if the monotonic predicate !Pred becomes known in the

    // first iteration of the loop body after peeling.

    if (NewPeelCount > DesiredPeelCount &&

        SE.isKnownPredicate(ICmpInst::getInversePredicate(Pred), IterVal,

    // With *that* peel count, does the predicate !Pred become known in the

    // first iteration of the loop body after peeling?

    if (!SE.isKnownPredicate(ICmpInst::getInversePredicate(Pred), IterVal,

                             RightSCEV))

      DesiredPeelCount = NewPeelCount;

      continue; // If not, give up.



    // However, for equality comparisons, that isn't always sufficient to

    // eliminate the comparsion in loop body, we may need to peel one more

    // iteration. See if that makes !Pred become unknown again.

    if (ICmpInst::isEquality(Pred) &&

        !SE.isKnownPredicate(ICmpInst::getInversePredicate(Pred), NextIterVal,

                             RightSCEV)) {

      assert(!SE.isKnownPredicate(Pred, IterVal, RightSCEV) &&

             SE.isKnownPredicate(Pred, NextIterVal, RightSCEV) &&

             "Expected Pred to go from known to unknown.");

      if (!CanPeelOneMoreIteration())

        continue; // Need to peel one more iteration, but can't. Give up.

      PeelOneMoreIteration(); // Great!

    }



    DesiredPeelCount = std::max(DesiredPeelCount, NewPeelCount);

  }



  return DesiredPeelCount;

llvm/test/Transforms/LoopUnroll/peel-loop-conditions.ll

+172 −22
Original line number Diff line number Diff line
@@ -524,18 +524,73 @@ for.end: 
define void @test7(i32 %k) {

; CHECK-LABEL: @test7(

; CHECK-NEXT:  for.body.lr.ph:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL_BEGIN:%.*]]

; CHECK:       for.body.peel.begin:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL:%.*]]

; CHECK:       for.body.peel:

; CHECK-NEXT:    [[CMP1_PEEL:%.*]] = icmp ne i32 0, 3

; CHECK-NEXT:    br i1 [[CMP1_PEEL]], label [[IF_THEN_PEEL:%.*]], label [[FOR_INC_PEEL:%.*]]

; CHECK:       if.then.peel:

; CHECK-NEXT:    call void @f1()

; CHECK-NEXT:    br label [[FOR_INC_PEEL]]

; CHECK:       for.inc.peel:

; CHECK-NEXT:    [[INC_PEEL:%.*]] = add nsw i32 0, 1

; CHECK-NEXT:    [[CMP_PEEL:%.*]] = icmp slt i32 [[INC_PEEL]], [[K:%.*]]

; CHECK-NEXT:    br i1 [[CMP_PEEL]], label [[FOR_BODY_PEEL_NEXT:%.*]], label [[FOR_END:%.*]]

; CHECK:       for.body.peel.next:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL2:%.*]]

; CHECK:       for.body.peel2:

; CHECK-NEXT:    [[CMP1_PEEL3:%.*]] = icmp ne i32 [[INC_PEEL]], 3

; CHECK-NEXT:    br i1 [[CMP1_PEEL3]], label [[IF_THEN_PEEL4:%.*]], label [[FOR_INC_PEEL5:%.*]]

; CHECK:       if.then.peel4:

; CHECK-NEXT:    call void @f1()

; CHECK-NEXT:    br label [[FOR_INC_PEEL5]]

; CHECK:       for.inc.peel5:

; CHECK-NEXT:    [[INC_PEEL6:%.*]] = add nsw i32 [[INC_PEEL]], 1

; CHECK-NEXT:    [[CMP_PEEL7:%.*]] = icmp slt i32 [[INC_PEEL6]], [[K]]

; CHECK-NEXT:    br i1 [[CMP_PEEL7]], label [[FOR_BODY_PEEL_NEXT1:%.*]], label [[FOR_END]]

; CHECK:       for.body.peel.next1:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL9:%.*]]

; CHECK:       for.body.peel9:

; CHECK-NEXT:    [[CMP1_PEEL10:%.*]] = icmp ne i32 [[INC_PEEL6]], 3

; CHECK-NEXT:    br i1 [[CMP1_PEEL10]], label [[IF_THEN_PEEL11:%.*]], label [[FOR_INC_PEEL12:%.*]]

; CHECK:       if.then.peel11:

; CHECK-NEXT:    call void @f1()

; CHECK-NEXT:    br label [[FOR_INC_PEEL12]]

; CHECK:       for.inc.peel12:

; CHECK-NEXT:    [[INC_PEEL13:%.*]] = add nsw i32 [[INC_PEEL6]], 1

; CHECK-NEXT:    [[CMP_PEEL14:%.*]] = icmp slt i32 [[INC_PEEL13]], [[K]]

; CHECK-NEXT:    br i1 [[CMP_PEEL14]], label [[FOR_BODY_PEEL_NEXT8:%.*]], label [[FOR_END]]

; CHECK:       for.body.peel.next8:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL16:%.*]]

; CHECK:       for.body.peel16:

; CHECK-NEXT:    [[CMP1_PEEL17:%.*]] = icmp ne i32 [[INC_PEEL13]], 3

; CHECK-NEXT:    br i1 [[CMP1_PEEL17]], label [[IF_THEN_PEEL18:%.*]], label [[FOR_INC_PEEL19:%.*]]

; CHECK:       if.then.peel18:

; CHECK-NEXT:    call void @f1()

; CHECK-NEXT:    br label [[FOR_INC_PEEL19]]

; CHECK:       for.inc.peel19:

; CHECK-NEXT:    [[INC_PEEL20:%.*]] = add nsw i32 [[INC_PEEL13]], 1

; CHECK-NEXT:    [[CMP_PEEL21:%.*]] = icmp slt i32 [[INC_PEEL20]], [[K]]

; CHECK-NEXT:    br i1 [[CMP_PEEL21]], label [[FOR_BODY_PEEL_NEXT15:%.*]], label [[FOR_END]]

; CHECK:       for.body.peel.next15:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL_NEXT22:%.*]]

; CHECK:       for.body.peel.next22:

; CHECK-NEXT:    br label [[FOR_BODY_LR_PH_PEEL_NEWPH:%.*]]

; CHECK:       for.body.lr.ph.peel.newph:

; CHECK-NEXT:    br label [[FOR_BODY:%.*]]

; CHECK:       for.body:

; CHECK-NEXT:    [[I_05:%.*]] = phi i32 [ 0, [[FOR_BODY_LR_PH:%.*]] ], [ [[INC:%.*]], [[FOR_INC:%.*]] ]

; CHECK-NEXT:    [[CMP1:%.*]] = icmp ne i32 [[I_05]], 3

; CHECK-NEXT:    br i1 [[CMP1]], label [[IF_THEN:%.*]], label [[FOR_INC]]

; CHECK-NEXT:    [[I_05:%.*]] = phi i32 [ [[INC_PEEL20]], [[FOR_BODY_LR_PH_PEEL_NEWPH]] ], [ [[INC:%.*]], [[FOR_INC:%.*]] ]

; CHECK-NEXT:    br i1 true, label [[IF_THEN:%.*]], label [[FOR_INC]]

; CHECK:       if.then:

; CHECK-NEXT:    call void @f1()

; CHECK-NEXT:    br label [[FOR_INC]]

; CHECK:       for.inc:

; CHECK-NEXT:    [[INC]] = add nsw i32 [[I_05]], 1

; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[INC]], [[K:%.*]]

; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]

; CHECK-NEXT:    [[INC]] = add nuw nsw i32 [[I_05]], 1

; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[INC]], [[K]]

; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END_LOOPEXIT:%.*]], !llvm.loop !6

; CHECK:       for.end.loopexit:

; CHECK-NEXT:    br label [[FOR_END]]

; CHECK:       for.end:

; CHECK-NEXT:    ret void

;
@@ -563,18 +618,73 @@ for.end: 
define void @test8(i32 %k) {

; CHECK-LABEL: @test8(

; CHECK-NEXT:  for.body.lr.ph:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL_BEGIN:%.*]]

; CHECK:       for.body.peel.begin:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL:%.*]]

; CHECK:       for.body.peel:

; CHECK-NEXT:    [[CMP1_PEEL:%.*]] = icmp eq i32 0, 3

; CHECK-NEXT:    br i1 [[CMP1_PEEL]], label [[IF_THEN_PEEL:%.*]], label [[FOR_INC_PEEL:%.*]]

; CHECK:       if.then.peel:

; CHECK-NEXT:    call void @f1()

; CHECK-NEXT:    br label [[FOR_INC_PEEL]]

; CHECK:       for.inc.peel:

; CHECK-NEXT:    [[INC_PEEL:%.*]] = add nsw i32 0, 1

; CHECK-NEXT:    [[CMP_PEEL:%.*]] = icmp slt i32 [[INC_PEEL]], [[K:%.*]]

; CHECK-NEXT:    br i1 [[CMP_PEEL]], label [[FOR_BODY_PEEL_NEXT:%.*]], label [[FOR_END:%.*]]

; CHECK:       for.body.peel.next:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL2:%.*]]

; CHECK:       for.body.peel2:

; CHECK-NEXT:    [[CMP1_PEEL3:%.*]] = icmp eq i32 [[INC_PEEL]], 3

; CHECK-NEXT:    br i1 [[CMP1_PEEL3]], label [[IF_THEN_PEEL4:%.*]], label [[FOR_INC_PEEL5:%.*]]

; CHECK:       if.then.peel4:

; CHECK-NEXT:    call void @f1()

; CHECK-NEXT:    br label [[FOR_INC_PEEL5]]

; CHECK:       for.inc.peel5:

; CHECK-NEXT:    [[INC_PEEL6:%.*]] = add nsw i32 [[INC_PEEL]], 1

; CHECK-NEXT:    [[CMP_PEEL7:%.*]] = icmp slt i32 [[INC_PEEL6]], [[K]]

; CHECK-NEXT:    br i1 [[CMP_PEEL7]], label [[FOR_BODY_PEEL_NEXT1:%.*]], label [[FOR_END]]

; CHECK:       for.body.peel.next1:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL9:%.*]]

; CHECK:       for.body.peel9:

; CHECK-NEXT:    [[CMP1_PEEL10:%.*]] = icmp eq i32 [[INC_PEEL6]], 3

; CHECK-NEXT:    br i1 [[CMP1_PEEL10]], label [[IF_THEN_PEEL11:%.*]], label [[FOR_INC_PEEL12:%.*]]

; CHECK:       if.then.peel11:

; CHECK-NEXT:    call void @f1()

; CHECK-NEXT:    br label [[FOR_INC_PEEL12]]

; CHECK:       for.inc.peel12:

; CHECK-NEXT:    [[INC_PEEL13:%.*]] = add nsw i32 [[INC_PEEL6]], 1

; CHECK-NEXT:    [[CMP_PEEL14:%.*]] = icmp slt i32 [[INC_PEEL13]], [[K]]

; CHECK-NEXT:    br i1 [[CMP_PEEL14]], label [[FOR_BODY_PEEL_NEXT8:%.*]], label [[FOR_END]]

; CHECK:       for.body.peel.next8:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL16:%.*]]

; CHECK:       for.body.peel16:

; CHECK-NEXT:    [[CMP1_PEEL17:%.*]] = icmp eq i32 [[INC_PEEL13]], 3

; CHECK-NEXT:    br i1 [[CMP1_PEEL17]], label [[IF_THEN_PEEL18:%.*]], label [[FOR_INC_PEEL19:%.*]]

; CHECK:       if.then.peel18:

; CHECK-NEXT:    call void @f1()

; CHECK-NEXT:    br label [[FOR_INC_PEEL19]]

; CHECK:       for.inc.peel19:

; CHECK-NEXT:    [[INC_PEEL20:%.*]] = add nsw i32 [[INC_PEEL13]], 1

; CHECK-NEXT:    [[CMP_PEEL21:%.*]] = icmp slt i32 [[INC_PEEL20]], [[K]]

; CHECK-NEXT:    br i1 [[CMP_PEEL21]], label [[FOR_BODY_PEEL_NEXT15:%.*]], label [[FOR_END]]

; CHECK:       for.body.peel.next15:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL_NEXT22:%.*]]

; CHECK:       for.body.peel.next22:

; CHECK-NEXT:    br label [[FOR_BODY_LR_PH_PEEL_NEWPH:%.*]]

; CHECK:       for.body.lr.ph.peel.newph:

; CHECK-NEXT:    br label [[FOR_BODY:%.*]]

; CHECK:       for.body:

; CHECK-NEXT:    [[I_05:%.*]] = phi i32 [ 0, [[FOR_BODY_LR_PH:%.*]] ], [ [[INC:%.*]], [[FOR_INC:%.*]] ]

; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq i32 [[I_05]], 3

; CHECK-NEXT:    br i1 [[CMP1]], label [[IF_THEN:%.*]], label [[FOR_INC]]

; CHECK-NEXT:    [[I_05:%.*]] = phi i32 [ [[INC_PEEL20]], [[FOR_BODY_LR_PH_PEEL_NEWPH]] ], [ [[INC:%.*]], [[FOR_INC:%.*]] ]

; CHECK-NEXT:    br i1 false, label [[IF_THEN:%.*]], label [[FOR_INC]]

; CHECK:       if.then:

; CHECK-NEXT:    call void @f1()

; CHECK-NEXT:    br label [[FOR_INC]]

; CHECK:       for.inc:

; CHECK-NEXT:    [[INC]] = add nsw i32 [[I_05]], 1

; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[INC]], [[K:%.*]]

; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]

; CHECK-NEXT:    [[INC]] = add nuw nsw i32 [[I_05]], 1

; CHECK-NEXT:    [[CMP:%.*]] = icmp slt i32 [[INC]], [[K]]

; CHECK-NEXT:    br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END_LOOPEXIT:%.*]], !llvm.loop !7

; CHECK:       for.end.loopexit:

; CHECK-NEXT:    br label [[FOR_END]]

; CHECK:       for.end:

; CHECK-NEXT:    ret void

;
@@ -683,7 +793,7 @@ define void @test_10__peel_first_iter_via_slt_pred(i32 %len) { 
; CHECK-NEXT:    call void @sink()

; CHECK-NEXT:    [[INC]] = add nuw nsw i32 [[I_06]], 1

; CHECK-NEXT:    [[EXITCOND:%.*]] = icmp eq i32 [[INC]], [[LEN]]

; CHECK-NEXT:    br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP_LOOPEXIT_LOOPEXIT:%.*]], label [[FOR_BODY]], !llvm.loop !6

; CHECK-NEXT:    br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP_LOOPEXIT_LOOPEXIT:%.*]], label [[FOR_BODY]], !llvm.loop !8

;

entry:

  %cmp5 = icmp sgt i32 %len, 0
@@ -750,7 +860,7 @@ define void @test_11__peel_first_iter_via_sgt_pred(i32 %len) { 
; CHECK-NEXT:    call void @sink()

; CHECK-NEXT:    [[INC]] = add nuw nsw i32 [[I_06]], 1

; CHECK-NEXT:    [[EXITCOND:%.*]] = icmp eq i32 [[INC]], [[LEN]]

; CHECK-NEXT:    br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP_LOOPEXIT_LOOPEXIT:%.*]], label [[FOR_BODY]], !llvm.loop !8

; CHECK-NEXT:    br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP_LOOPEXIT_LOOPEXIT:%.*]], label [[FOR_BODY]], !llvm.loop !10

;

entry:

  %cmp5 = icmp sgt i32 %len, 0
@@ -783,15 +893,35 @@ define void @test12__peel_first_iter_via_eq_pred(i32 %len) { 
; CHECK-NEXT:    [[CMP5:%.*]] = icmp sgt i32 [[LEN:%.*]], 0

; CHECK-NEXT:    br i1 [[CMP5]], label [[FOR_BODY_PREHEADER:%.*]], label [[FOR_COND_CLEANUP:%.*]]

; CHECK:       for.body.preheader:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL_BEGIN:%.*]]

; CHECK:       for.body.peel.begin:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL:%.*]]

; CHECK:       for.body.peel:

; CHECK-NEXT:    [[CMP1_PEEL:%.*]] = icmp eq i32 0, 0

; CHECK-NEXT:    br i1 [[CMP1_PEEL]], label [[IF_THEN_PEEL:%.*]], label [[IF_END_PEEL:%.*]]

; CHECK:       if.then.peel:

; CHECK-NEXT:    call void @init()

; CHECK-NEXT:    br label [[IF_END_PEEL]]

; CHECK:       if.end.peel:

; CHECK-NEXT:    call void @sink()

; CHECK-NEXT:    [[INC_PEEL:%.*]] = add nuw nsw i32 0, 1

; CHECK-NEXT:    [[EXITCOND_PEEL:%.*]] = icmp eq i32 [[INC_PEEL]], [[LEN]]

; CHECK-NEXT:    br i1 [[EXITCOND_PEEL]], label [[FOR_COND_CLEANUP_LOOPEXIT:%.*]], label [[FOR_BODY_PEEL_NEXT:%.*]]

; CHECK:       for.body.peel.next:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL_NEXT1:%.*]]

; CHECK:       for.body.peel.next1:

; CHECK-NEXT:    br label [[FOR_BODY_PREHEADER_PEEL_NEWPH:%.*]]

; CHECK:       for.body.preheader.peel.newph:

; CHECK-NEXT:    br label [[FOR_BODY:%.*]]

; CHECK:       for.cond.cleanup.loopexit.loopexit:

; CHECK-NEXT:    br label [[FOR_COND_CLEANUP_LOOPEXIT]]

; CHECK:       for.cond.cleanup.loopexit:

; CHECK-NEXT:    br label [[FOR_COND_CLEANUP]]

; CHECK:       for.cond.cleanup:

; CHECK-NEXT:    ret void

; CHECK:       for.body:

; CHECK-NEXT:    [[I_06:%.*]] = phi i32 [ [[INC:%.*]], [[IF_END:%.*]] ], [ 0, [[FOR_BODY_PREHEADER]] ]

; CHECK-NEXT:    [[CMP1:%.*]] = icmp eq i32 [[I_06]], 0

; CHECK-NEXT:    br i1 [[CMP1]], label [[IF_THEN:%.*]], label [[IF_END]]

; CHECK-NEXT:    [[I_06:%.*]] = phi i32 [ [[INC:%.*]], [[IF_END:%.*]] ], [ [[INC_PEEL]], [[FOR_BODY_PREHEADER_PEEL_NEWPH]] ]

; CHECK-NEXT:    br i1 false, label [[IF_THEN:%.*]], label [[IF_END]]

; CHECK:       if.then:

; CHECK-NEXT:    call void @init()

; CHECK-NEXT:    br label [[IF_END]]
@@ -799,7 +929,7 @@ define void @test12__peel_first_iter_via_eq_pred(i32 %len) { 
; CHECK-NEXT:    call void @sink()

; CHECK-NEXT:    [[INC]] = add nuw nsw i32 [[I_06]], 1

; CHECK-NEXT:    [[EXITCOND:%.*]] = icmp eq i32 [[INC]], [[LEN]]

; CHECK-NEXT:    br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP_LOOPEXIT:%.*]], label [[FOR_BODY]]

; CHECK-NEXT:    br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP_LOOPEXIT_LOOPEXIT:%.*]], label [[FOR_BODY]], !llvm.loop !11

;

entry:

  %cmp5 = icmp sgt i32 %len, 0
@@ -832,15 +962,35 @@ define void @test13__peel_first_iter_via_ne_pred(i32 %len) { 
; CHECK-NEXT:    [[CMP5:%.*]] = icmp sgt i32 [[LEN:%.*]], 0

; CHECK-NEXT:    br i1 [[CMP5]], label [[FOR_BODY_PREHEADER:%.*]], label [[FOR_COND_CLEANUP:%.*]]

; CHECK:       for.body.preheader:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL_BEGIN:%.*]]

; CHECK:       for.body.peel.begin:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL:%.*]]

; CHECK:       for.body.peel:

; CHECK-NEXT:    [[CMP1_PEEL:%.*]] = icmp ne i32 0, 0

; CHECK-NEXT:    br i1 [[CMP1_PEEL]], label [[IF_END_PEEL:%.*]], label [[IF_THEN_PEEL:%.*]]

; CHECK:       if.then.peel:

; CHECK-NEXT:    call void @init()

; CHECK-NEXT:    br label [[IF_END_PEEL]]

; CHECK:       if.end.peel:

; CHECK-NEXT:    call void @sink()

; CHECK-NEXT:    [[INC_PEEL:%.*]] = add nuw nsw i32 0, 1

; CHECK-NEXT:    [[EXITCOND_PEEL:%.*]] = icmp eq i32 [[INC_PEEL]], [[LEN]]

; CHECK-NEXT:    br i1 [[EXITCOND_PEEL]], label [[FOR_COND_CLEANUP_LOOPEXIT:%.*]], label [[FOR_BODY_PEEL_NEXT:%.*]]

; CHECK:       for.body.peel.next:

; CHECK-NEXT:    br label [[FOR_BODY_PEEL_NEXT1:%.*]]

; CHECK:       for.body.peel.next1:

; CHECK-NEXT:    br label [[FOR_BODY_PREHEADER_PEEL_NEWPH:%.*]]

; CHECK:       for.body.preheader.peel.newph:

; CHECK-NEXT:    br label [[FOR_BODY:%.*]]

; CHECK:       for.cond.cleanup.loopexit.loopexit:

; CHECK-NEXT:    br label [[FOR_COND_CLEANUP_LOOPEXIT]]

; CHECK:       for.cond.cleanup.loopexit:

; CHECK-NEXT:    br label [[FOR_COND_CLEANUP]]

; CHECK:       for.cond.cleanup:

; CHECK-NEXT:    ret void

; CHECK:       for.body:

; CHECK-NEXT:    [[I_06:%.*]] = phi i32 [ [[INC:%.*]], [[IF_END:%.*]] ], [ 0, [[FOR_BODY_PREHEADER]] ]

; CHECK-NEXT:    [[CMP1:%.*]] = icmp ne i32 [[I_06]], 0

; CHECK-NEXT:    br i1 [[CMP1]], label [[IF_END]], label [[IF_THEN:%.*]]

; CHECK-NEXT:    [[I_06:%.*]] = phi i32 [ [[INC:%.*]], [[IF_END:%.*]] ], [ [[INC_PEEL]], [[FOR_BODY_PREHEADER_PEEL_NEWPH]] ]

; CHECK-NEXT:    br i1 true, label [[IF_END]], label [[IF_THEN:%.*]]

; CHECK:       if.then:

; CHECK-NEXT:    call void @init()

; CHECK-NEXT:    br label [[IF_END]]
@@ -848,7 +998,7 @@ define void @test13__peel_first_iter_via_ne_pred(i32 %len) { 
; CHECK-NEXT:    call void @sink()

; CHECK-NEXT:    [[INC]] = add nuw nsw i32 [[I_06]], 1

; CHECK-NEXT:    [[EXITCOND:%.*]] = icmp eq i32 [[INC]], [[LEN]]

; CHECK-NEXT:    br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP_LOOPEXIT:%.*]], label [[FOR_BODY]]

; CHECK-NEXT:    br i1 [[EXITCOND]], label [[FOR_COND_CLEANUP_LOOPEXIT_LOOPEXIT:%.*]], label [[FOR_BODY]], !llvm.loop !12

;

entry:

  %cmp5 = icmp sgt i32 %len, 0