# RUN: llc -mtriple=thumbv8.1m.main -run-pass=arm-low-overhead-loops --verify-machineinstrs %s -o - | FileCheck %s
# CHECK-NOT: t2DLS
# CHECK: bb.5.for.inc16:
# CHECK:      $lr = t2SUBri killed renamable $lr, 1, 14 /* CC::al */, $noreg, def $cpsr
# CHECK-NOT:  t2CMPri $lr
# CHECK:      tBcc %bb.6, 1 /* CC::ne */
# CHECK:      tB %bb.2
# CHECK: bb.6.for.cond4.preheader:

--- |
  ; ModuleID = 'revert-non-header.ll'
  source_filename = "revert-non-header.ll"
  target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
  target triple = "thumbv8.1m.main"
  
  define void @header_not_target_unrolled_loop(i32* nocapture %v, i32 %n) {
  entry:
    %cmp56 = icmp sgt i32 %n, 1
    br i1 %cmp56, label %for.cond1.preheader.preheader, label %for.end20
  
  for.cond1.preheader.preheader:                    ; preds = %entry
    br label %for.cond1.preheader
  
  for.cond.loopexit:                                ; preds = %for.inc16, %for.cond1.preheader
    %cmp = icmp sgt i32 %gap.057.in, 3
    br i1 %cmp, label %for.cond1.preheader, label %for.end20
  
  for.cond1.preheader:                              ; preds = %for.cond1.preheader.preheader, %for.cond.loopexit
    %gap.057.in = phi i32 [ %gap.057, %for.cond.loopexit ], [ %n, %for.cond1.preheader.preheader ]
    %gap.057 = sdiv i32 %gap.057.in, 2
    %cmp252 = icmp slt i32 %gap.057, %n
    %tmp = sub i32 %n, %gap.057
    call void @llvm.set.loop.iterations.i32(i32 %tmp)
    br i1 %cmp252, label %for.cond4.preheader.preheader, label %for.cond.loopexit
  
  for.cond4.preheader.preheader:                    ; preds = %for.cond1.preheader
    %tmp2 = mul i32 %gap.057, -4
    %tmp6 = mul i32 %gap.057, -2
    %scevgep1 = getelementptr i32, i32* %v, i32 %gap.057
    %0 = shl i32 %gap.057, 2
    br label %for.cond4.preheader
  
  for.cond4.preheader:                              ; preds = %for.inc16, %for.cond4.preheader.preheader
    %lsr.iv2 = phi i32* [ %scevgep3, %for.inc16 ], [ %scevgep1, %for.cond4.preheader.preheader ]
    %lsr.iv = phi i32* [ %v, %for.cond4.preheader.preheader ], [ %scevgep, %for.inc16 ]
    %i.053 = phi i32 [ %inc, %for.inc16 ], [ %gap.057, %for.cond4.preheader.preheader ]
    %tmp8 = phi i32 [ %tmp, %for.cond4.preheader.preheader ], [ %tmp16, %for.inc16 ]
    %j.048 = sub nsw i32 %i.053, %gap.057
    %cmp549 = icmp sgt i32 %j.048, -1
    br i1 %cmp549, label %land.rhs.preheader, label %for.inc16
  
  land.rhs.preheader:                               ; preds = %for.cond4.preheader
    br label %land.rhs
  
  land.rhs:                                         ; preds = %land.rhs.preheader, %for.body8
    %lsr.iv4 = phi i32 [ %lsr.iv.next, %for.body8 ], [ 0, %land.rhs.preheader ]
    %j.051 = phi i32 [ %j.0, %for.body8 ], [ %j.048, %land.rhs.preheader ]
    %1 = bitcast i32* %lsr.iv2 to i8*
    %2 = bitcast i32* %lsr.iv to i8*
    %uglygep3 = getelementptr i8, i8* %2, i32 %lsr.iv4
    %uglygep34 = bitcast i8* %uglygep3 to i32*
    %tmp9 = load i32, i32* %uglygep34, align 4
    %uglygep1 = getelementptr i8, i8* %1, i32 %lsr.iv4
    %uglygep12 = bitcast i8* %uglygep1 to i32*
    %tmp12 = load i32, i32* %uglygep12, align 4
    %cmp7 = icmp sgt i32 %tmp9, %tmp12
    br i1 %cmp7, label %for.body8, label %for.inc16
  
  for.body8:                                        ; preds = %land.rhs
    %3 = bitcast i32* %lsr.iv2 to i8*
    %4 = bitcast i32* %lsr.iv to i8*
    %sunkaddr = getelementptr i8, i8* %4, i32 %lsr.iv4
    %5 = bitcast i8* %sunkaddr to i32*
    store i32 %tmp12, i32* %5, align 4
    %uglygep = getelementptr i8, i8* %3, i32 %lsr.iv4
    %uglygep6 = bitcast i8* %uglygep to i32*
    store i32 %tmp9, i32* %uglygep6, align 4
    %j.0 = sub nsw i32 %j.051, %gap.057
    %lsr.iv.next = add i32 %lsr.iv4, %0
    %cmp5 = icmp sgt i32 %j.0, -1
    br i1 %cmp5, label %land.rhs, label %for.inc16
  
  for.inc16:                                        ; preds = %for.body8, %land.rhs, %for.cond4.preheader
    %inc = add nsw i32 %i.053, 1
    %scevgep = getelementptr i32, i32* %lsr.iv, i32 1
    %tmp16 = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 %tmp8, i32 1)
    %tmp17 = icmp ne i32 %tmp16, 0
    %scevgep3 = getelementptr i32, i32* %lsr.iv2, i32 1
    br i1 %tmp17, label %for.cond4.preheader, label %for.cond.loopexit
  
  for.end20:                                        ; preds = %for.cond.loopexit, %entry
    ret void
  }
  
  ; Function Attrs: noduplicate nounwind
  declare void @llvm.set.loop.iterations.i32(i32) #0
  
  ; Function Attrs: noduplicate nounwind
  declare i32 @llvm.loop.decrement.reg.i32.i32.i32(i32, i32) #0
  
  ; Function Attrs: nounwind
  declare void @llvm.stackprotector(i8*, i8**) #1
  
  attributes #0 = { noduplicate nounwind }
  attributes #1 = { nounwind }

...
---
name:            header_not_target_unrolled_loop
alignment:       2
exposesReturnsTwice: false
legalized:       false
regBankSelected: false
selected:        false
failedISel:      false
tracksRegLiveness: true
hasWinCFI:       false
registers:       []
liveins:
  - { reg: '$r0', virtual-reg: '' }
  - { reg: '$r1', virtual-reg: '' }
frameInfo:
  isFrameAddressTaken: false
  isReturnAddressTaken: false
  hasStackMap:     false
  hasPatchPoint:   false
  stackSize:       32
  offsetAdjustment: 0
  maxAlignment:    4
  adjustsStack:    false
  hasCalls:        false
  stackProtector:  ''
  maxCallFrameSize: 0
  cvBytesOfCalleeSavedRegisters: 0
  hasOpaqueSPAdjustment: false
  hasVAStart:      false
  hasMustTailInVarArgFunc: false
  localFrameSize:  0
  savePoint:       ''
  restorePoint:    ''
fixedStack:      []
stack:
  - { id: 0, name: '', type: spill-slot, offset: -4, size: 4, alignment: 4, 
      stack-id: default, callee-saved-register: '$lr', callee-saved-restored: false, 
      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
  - { id: 1, name: '', type: spill-slot, offset: -8, size: 4, alignment: 4, 
      stack-id: default, callee-saved-register: '$r10', callee-saved-restored: true, 
      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
  - { id: 2, name: '', type: spill-slot, offset: -12, size: 4, alignment: 4, 
      stack-id: default, callee-saved-register: '$r9', callee-saved-restored: true, 
      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
  - { id: 3, name: '', type: spill-slot, offset: -16, size: 4, alignment: 4, 
      stack-id: default, callee-saved-register: '$r8', callee-saved-restored: true, 
      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
  - { id: 4, name: '', type: spill-slot, offset: -20, size: 4, alignment: 4, 
      stack-id: default, callee-saved-register: '$r7', callee-saved-restored: true, 
      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
  - { id: 5, name: '', type: spill-slot, offset: -24, size: 4, alignment: 4, 
      stack-id: default, callee-saved-register: '$r6', callee-saved-restored: true, 
      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
  - { id: 6, name: '', type: spill-slot, offset: -28, size: 4, alignment: 4, 
      stack-id: default, callee-saved-register: '$r5', callee-saved-restored: true, 
      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
  - { id: 7, name: '', type: spill-slot, offset: -32, size: 4, alignment: 4, 
      stack-id: default, callee-saved-register: '$r4', callee-saved-restored: true, 
      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
callSites:       []
constants:       []
machineFunctionInfo: {}
body:             |
  bb.0.entry:
    successors: %bb.1(0x40000000), %bb.9(0x40000000)
    liveins: $r0, $r1, $r4, $r5, $r6, $r7, $r8, $r9, $r10, $lr
  
    $sp = frame-setup t2STMDB_UPD $sp, 14, $noreg, killed $r4, killed $r5, killed $r6, killed $r7, killed $r8, killed $r9, killed $r10, killed $lr
    frame-setup CFI_INSTRUCTION def_cfa_offset 32
    frame-setup CFI_INSTRUCTION offset $lr, -4
    frame-setup CFI_INSTRUCTION offset $r10, -8
    frame-setup CFI_INSTRUCTION offset $r9, -12
    frame-setup CFI_INSTRUCTION offset $r8, -16
    frame-setup CFI_INSTRUCTION offset $r7, -20
    frame-setup CFI_INSTRUCTION offset $r6, -24
    frame-setup CFI_INSTRUCTION offset $r5, -28
    frame-setup CFI_INSTRUCTION offset $r4, -32
    tCMPi8 renamable $r1, 2, 14, $noreg, implicit-def $cpsr
    tBcc %bb.9, 11, killed $cpsr
  
  bb.1:
    successors: %bb.3(0x80000000)
    liveins: $r0, $r1
  
    $r9 = tMOVr $r1, 14, $noreg
    tB %bb.3, 14, $noreg
  
  bb.2.for.cond.loopexit:
    successors: %bb.3(0x7c000000), %bb.9(0x04000000)
    liveins: $r0, $r1, $r9, $r12
  
    t2CMPri killed renamable $r12, 4, 14, $noreg, implicit-def $cpsr
    tBcc %bb.9, 11, killed $cpsr
  
  bb.3.for.cond1.preheader:
    successors: %bb.4(0x40000000), %bb.2(0x40000000)
    liveins: $r0, $r1, $r9
  
    renamable $r2 = t2ADDrs $r9, $r9, 251, 14, $noreg, $noreg
    $r12 = tMOVr killed $r9, 14, $noreg
    renamable $lr = t2SUBrs renamable $r1, renamable $r2, 9, 14, $noreg, $noreg
    renamable $r9 = t2ASRri renamable $r2, 1, 14, $noreg, $noreg
    t2CMPrs renamable $r1, killed renamable $r2, 9, 14, $noreg, implicit-def $cpsr
    t2DoLoopStart renamable $lr
    tBcc %bb.2, 13, killed $cpsr
  
  bb.4.for.cond4.preheader.preheader:
    successors: %bb.7(0x50000000), %bb.5(0x30000000)
    liveins: $lr, $r0, $r1, $r9, $r12
  
    renamable $r3 = t2ADDrs renamable $r0, renamable $r9, 18, 14, $noreg, $noreg
    renamable $r10 = t2LSLri renamable $r9, 2, 14, $noreg, $noreg
    $r5 = tMOVr $r0, 14, $noreg
    $r8 = tMOVr $r9, 14, $noreg
    renamable $r7 = nsw t2SUBrr renamable $r8, renamable $r9, 14, $noreg, def $cpsr
    tBcc %bb.7, 5, killed $cpsr
  
  bb.5.for.inc16:
    successors: %bb.6(0x7c000000), %bb.2(0x04000000)
    liveins: $lr, $r0, $r1, $r3, $r5, $r8, $r9, $r10, $r12
  
    renamable $r3, dead $cpsr = tADDi8 killed renamable $r3, 4, 14, $noreg
    renamable $r5, dead $cpsr = tADDi8 killed renamable $r5, 4, 14, $noreg
    renamable $r8 = nsw t2ADDri killed renamable $r8, 1, 14, $noreg, $noreg
    renamable $lr = t2LoopDec killed renamable $lr, 1
    t2LoopEnd renamable $lr, %bb.6, implicit-def dead $cpsr
    tB %bb.2, 14, $noreg
  
  bb.6.for.cond4.preheader:
    successors: %bb.7(0x50000000), %bb.5(0x30000000)
    liveins: $lr, $r0, $r1, $r3, $r5, $r8, $r9, $r10, $r12
  
    renamable $r7 = nsw t2SUBrr renamable $r8, renamable $r9, 14, $noreg, def $cpsr
    tBcc %bb.5, 4, killed $cpsr
  
  bb.7.land.rhs.preheader:
    successors: %bb.8(0x80000000)
    liveins: $lr, $r0, $r1, $r3, $r5, $r7, $r8, $r9, $r10, $r12
  
    renamable $r6, dead $cpsr = tMOVi8 0, 14, $noreg
  
  bb.8.land.rhs:
    successors: %bb.5(0x07e00000), %bb.8(0x78200000)
    liveins: $lr, $r0, $r1, $r3, $r5, $r6, $r7, $r8, $r9, $r10, $r12
  
    renamable $r4 = tLDRr renamable $r3, $r6, 14, $noreg :: (load 4 from %ir.uglygep12)
    renamable $r2 = tLDRr renamable $r5, $r6, 14, $noreg :: (load 4 from %ir.uglygep34)
    tCMPr renamable $r2, renamable $r4, 14, $noreg, implicit-def $cpsr
    t2IT 12, 1, implicit-def $itstate
    tSTRr killed renamable $r4, renamable $r5, $r6, 12, $cpsr, implicit $itstate :: (store 4 into %ir.5)
    tSTRr killed renamable $r2, renamable $r3, $r6, 12, $cpsr, implicit $itstate :: (store 4 into %ir.uglygep6)
    renamable $r6 = tADDhirr killed renamable $r6, renamable $r10, 12, $cpsr, implicit $r6, implicit $itstate
    renamable $r7 = nsw t2SUBrr killed renamable $r7, renamable $r9, 12, $cpsr, $noreg, implicit $r7, implicit killed $itstate
    t2IT 12, 8, implicit-def $itstate
    t2CMPri renamable $r7, -1, 12, killed $cpsr, implicit-def $cpsr, implicit killed $itstate
    tBcc %bb.8, 12, killed $cpsr
    tB %bb.5, 14, $noreg
  
  bb.9.for.end20:
    $sp = t2LDMIA_RET $sp, 14, $noreg, def $r4, def $r5, def $r6, def $r7, def $r8, def $r9, def $r10, def $pc

...