# RUN: llc -mtriple=thumbv8.1m.main %s -run-pass=arm-low-overhead-loops --verify-machineinstrs -o -
# CHECK:      bb.1.for.body.preheader:
# CHECK:        $lr = t2DLS
# CHECK-NOT:    t2LoopDec
# CHECK:      bb.6.for.inc:
# CHECK:        $lr = t2LEUpdate renamable $lr, %bb.2

--- |
  ; ModuleID = 'switch.ll'
  source_filename = "switch.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 dso_local arm_aapcscc i32 @search(i8* nocapture readonly %c, i32 %N) {
  entry:
    %cmp11 = icmp eq i32 %N, 0
    br i1 %cmp11, label %for.cond.cleanup, label %for.body.preheader
  
  for.body.preheader:                               ; preds = %entry
    %start = call i32 @llvm.start.loop.iterations.i32(i32 %N)
    br label %for.body
  
  for.cond.cleanup:                                 ; preds = %for.inc, %entry
    %found.0.lcssa = phi i32 [ 0, %entry ], [ %found.1, %for.inc ]
    %spaces.0.lcssa = phi i32 [ 0, %entry ], [ %spaces.1, %for.inc ]
    %sub = sub nsw i32 %found.0.lcssa, %spaces.0.lcssa
    ret i32 %sub
  
  for.body:                                         ; preds = %for.inc, %for.body.preheader
    %lsr.iv1 = phi i8* [ %c, %for.body.preheader ], [ %scevgep, %for.inc ]
    %spaces.013 = phi i32 [ %spaces.1, %for.inc ], [ 0, %for.body.preheader ]
    %found.012 = phi i32 [ %found.1, %for.inc ], [ 0, %for.body.preheader ]
    %0 = phi i32 [ %start, %for.body.preheader ], [ %3, %for.inc ]
    %1 = load i8, i8* %lsr.iv1, align 1
    %2 = zext i8 %1 to i32
    switch i32 %2, label %for.inc [
      i32 108, label %sw.bb
      i32 111, label %sw.bb
      i32 112, label %sw.bb
      i32 32, label %sw.bb1
    ]
  
  sw.bb:                                            ; preds = %for.body, %for.body, %for.body
    %inc = add nsw i32 %found.012, 1
    br label %for.inc
  
  sw.bb1:                                           ; preds = %for.body
    %inc2 = add nsw i32 %spaces.013, 1
    br label %for.inc
  
  for.inc:                                          ; preds = %sw.bb1, %sw.bb, %for.body
    %found.1 = phi i32 [ %found.012, %for.body ], [ %found.012, %sw.bb1 ], [ %inc, %sw.bb ]
    %spaces.1 = phi i32 [ %spaces.013, %for.body ], [ %inc2, %sw.bb1 ], [ %spaces.013, %sw.bb ]
    %scevgep = getelementptr i8, i8* %lsr.iv1, i32 1
    %3 = call i32 @llvm.loop.decrement.reg.i32.i32.i32(i32 %0, i32 1)
    %4 = icmp ne i32 %3, 0
    br i1 %4, label %for.body, label %for.cond.cleanup
  }
  
  ; Function Attrs: noduplicate nounwind
  declare i32 @llvm.start.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:            search
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:       8
  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: '$lr', callee-saved-restored: false, 
      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
  - { id: 1, name: '', type: spill-slot, offset: -8, size: 4, alignment: 4, 
      stack-id: default, callee-saved-register: '$r4', callee-saved-restored: true, 
      debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
callSites:       []
constants:       []
machineFunctionInfo: {}
body:             |
  bb.0.entry:
    successors: %bb.7(0x30000000), %bb.1(0x50000000)
    liveins: $r0, $r1, $r4, $lr
  
    frame-setup tPUSH 14, $noreg, killed $r4, killed $lr, implicit-def $sp, implicit $sp
    frame-setup CFI_INSTRUCTION def_cfa_offset 8
    frame-setup CFI_INSTRUCTION offset $lr, -4
    frame-setup CFI_INSTRUCTION offset $r4, -8
    tCBZ $r1, %bb.7
  
  bb.1.for.body.preheader:
    successors: %bb.4(0x80000000)
    liveins: $r0, $r1
  
    $lr = tMOVr $r1, 14, $noreg
    $lr = t2DoLoopStart killed $r1
    renamable $r1, dead $cpsr = tMOVi8 0, 14, $noreg
    renamable $r12 = t2MOVi 1, 14, $noreg, $noreg
    renamable $r2, dead $cpsr = tMOVi8 0, 14, $noreg
    tB %bb.4, 14, $noreg
  
  bb.2.for.body:
    successors: %bb.3(0x80000000)
    liveins: $lr, $r0, $r1, $r2, $r3, $r12
  
    tCMPi8 killed renamable $r3, 32, 14, $noreg, implicit-def $cpsr
    t2IT 0, 8, implicit-def $itstate
    renamable $r1 = nsw tADDi8 $noreg, killed renamable $r1, 1, 0, killed $cpsr, implicit $r1, implicit killed $itstate
  
  bb.3.for.inc:
    successors: %bb.4(0x7c000000), %bb.8(0x04000000)
    liveins: $lr, $r0, $r1, $r2, $r12
  
    renamable $r0, dead $cpsr = tADDi8 killed renamable $r0, 1, 14, $noreg
    renamable $lr = t2LoopDec killed renamable $lr, 1
    t2LoopEnd renamable $lr, %bb.4, implicit-def dead $cpsr
    tB %bb.8, 14, $noreg
  
  bb.4.for.body:
    successors: %bb.2(0x26666665), %bb.5(0x5999999b)
    liveins: $lr, $r0, $r1, $r2, $r12
  
    renamable $r3 = tLDRBi renamable $r0, 0, 14, $noreg :: (load 1 from %ir.lsr.iv1)
    renamable $r4 = t2SUBri renamable $r3, 108, 14, $noreg, $noreg
    tCMPi8 renamable $r4, 4, 14, $noreg, implicit-def $cpsr
    tBcc %bb.2, 8, killed $cpsr
  
  bb.5.for.body:
    successors: %bb.6(0x6db6db6e), %bb.2(0x12492492)
    liveins: $lr, $r0, $r1, $r2, $r3, $r4, $r12
  
    renamable $r4 = t2LSLrr renamable $r12, killed renamable $r4, 14, $noreg, $noreg
    t2TSTri killed renamable $r4, 25, 14, $noreg, implicit-def $cpsr
    tBcc %bb.2, 0, killed $cpsr
  
  bb.6.sw.bb:
    successors: %bb.3(0x80000000)
    liveins: $lr, $r0, $r1, $r2, $r12
  
    renamable $r2, dead $cpsr = nsw tADDi8 killed renamable $r2, 1, 14, $noreg
    tB %bb.3, 14, $noreg
  
  bb.7:
    successors: %bb.8(0x80000000)
  
    renamable $r2, dead $cpsr = tMOVi8 0, 14, $noreg
    renamable $r1, dead $cpsr = tMOVi8 0, 14, $noreg
  
  bb.8.for.cond.cleanup:
    liveins: $r1, $r2
  
    renamable $r0, dead $cpsr = nsw tSUBrr killed renamable $r2, killed renamable $r1, 14, $noreg
    tPOP_RET 14, $noreg, def $r4, def $pc, implicit killed $r0

...