; LLVM IR from priyankchheda/algorithms :: _other_languages/cpp/LinkedList (getNthNodeFromEnd)

; Unoptimized IR (clang -disable-llvm-passes):
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

%"struct.LinkedList::Node" = type { i32, ptr }

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: mustprogress uwtable
define dso_local noundef i32 @_Z35getNthFromEnd_UsingTwoPointerMethodPN10LinkedList10LinkedListIiEEi(ptr noundef %0, i32 noundef %1) #1 {
  %3 = alloca i32, align 4
  %4 = alloca ptr, align 8
  %5 = alloca i32, align 4
  %6 = alloca i32, align 4
  %7 = alloca ptr, align 8
  %8 = alloca i32, align 4
  %9 = alloca ptr, align 8
  %10 = alloca ptr, align 8
  %11 = alloca i32, align 4
  store ptr %0, ptr %4, align 8, !tbaa !5
  store i32 %1, ptr %5, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 4, ptr %6) #3
  %12 = load ptr, ptr %4, align 8, !tbaa !5
  %13 = call noundef i32 @_ZN10LinkedList10LinkedListIiE9getLengthEv(ptr noundef nonnull align 8 dereferenceable(8) %12)
  store i32 %13, ptr %6, align 4, !tbaa !9
  call void @llvm.lifetime.start.p0(i64 8, ptr %7) #3
  %14 = load ptr, ptr %4, align 8, !tbaa !5
  %15 = call noundef ptr @_ZN10LinkedList10LinkedListIiE7getHeadEv(ptr noundef nonnull align 8 dereferenceable(8) %14)
  store ptr %15, ptr %7, align 8, !tbaa !5
  %16 = load i32, ptr %5, align 4, !tbaa !9
  %17 = load i32, ptr %6, align 4, !tbaa !9
  %18 = add nsw i32 %17, 1
  %19 = icmp sge i32 %16, %18
  br i1 %19, label %23, label %20

20:                                               ; preds = %2
  %21 = load i32, ptr %5, align 4, !tbaa !9
  %22 = icmp sle i32 %21, 0
  br i1 %22, label %23, label %24

23:                                               ; preds = %20, %2
  store i32 -1, ptr %3, align 4
  store i32 1, ptr %8, align 4
  br label %56

24:                                               ; preds = %20
  call void @llvm.lifetime.start.p0(i64 8, ptr %9) #3
  %25 = load ptr, ptr %7, align 8, !tbaa !5
  store ptr %25, ptr %9, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %10) #3
  %26 = load ptr, ptr %7, align 8, !tbaa !5
  store ptr %26, ptr %10, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %11) #3
  store i32 1, ptr %11, align 4, !tbaa !9
  br label %27

27:                                               ; preds = %36, %24
  %28 = load i32, ptr %11, align 4, !tbaa !9
  %29 = load i32, ptr %5, align 4, !tbaa !9
  %30 = icmp slt i32 %28, %29
  br i1 %30, label %32, label %31

31:                                               ; preds = %27
  store i32 2, ptr %8, align 4
  call void @llvm.lifetime.end.p0(i64 4, ptr %11) #3
  br label %39

32:                                               ; preds = %27
  %33 = load ptr, ptr %10, align 8, !tbaa !5
  %34 = getelementptr inbounds %"struct.LinkedList::Node", ptr %33, i32 0, i32 1
  %35 = load ptr, ptr %34, align 8, !tbaa !11
  store ptr %35, ptr %10, align 8, !tbaa !5
  br label %36

36:                                               ; preds = %32
  %37 = load i32, ptr %11, align 4, !tbaa !9
  %38 = add nsw i32 %37, 1
  store i32 %38, ptr %11, align 4, !tbaa !9
  br label %27, !llvm.loop !13

39:                                               ; preds = %31
  br label %40

40:                                               ; preds = %45, %39
  %41 = load ptr, ptr %10, align 8, !tbaa !5
  %42 = getelementptr inbounds %"struct.LinkedList::Node", ptr %41, i32 0, i32 1
  %43 = load ptr, ptr %42, align 8, !tbaa !11
  %44 = icmp ne ptr %43, null
  br i1 %44, label %45, label %52

45:                                               ; preds = %40
  %46 = load ptr, ptr %9, align 8, !tbaa !5
  %47 = getelementptr inbounds %"struct.LinkedList::Node", ptr %46, i32 0, i32 1
  %48 = load ptr, ptr %47, align 8, !tbaa !11
  store ptr %48, ptr %9, align 8, !tbaa !5
  %49 = load ptr, ptr %10, align 8, !tbaa !5
  %50 = getelementptr inbounds %"struct.LinkedList::Node", ptr %49, i32 0, i32 1
  %51 = load ptr, ptr %50, align 8, !tbaa !11
  store ptr %51, ptr %10, align 8, !tbaa !5
  br label %40, !llvm.loop !15

52:                                               ; preds = %40
  %53 = load ptr, ptr %9, align 8, !tbaa !5
  %54 = getelementptr inbounds %"struct.LinkedList::Node", ptr %53, i32 0, i32 0
  %55 = load i32, ptr %54, align 8, !tbaa !16
  store i32 %55, ptr %3, align 4
  store i32 1, ptr %8, align 4
  call void @llvm.lifetime.end.p0(i64 8, ptr %10) #3
  call void @llvm.lifetime.end.p0(i64 8, ptr %9) #3
  br label %56

56:                                               ; preds = %52, %23
  call void @llvm.lifetime.end.p0(i64 8, ptr %7) #3
  call void @llvm.lifetime.end.p0(i64 4, ptr %6) #3
  %57 = load i32, ptr %3, align 4
  ret i32 %57
}

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #0

; Function Attrs: mustprogress nounwind uwtable
declare dso_local noundef i32 @_ZN10LinkedList10LinkedListIiE9getLengthEv(ptr noundef nonnull align 8 dereferenceable(8)) #2 align 2

; Function Attrs: mustprogress nounwind uwtable
declare dso_local noundef ptr @_ZN10LinkedList10LinkedListIiE7getHeadEv(ptr noundef nonnull align 8 dereferenceable(8)) #2 align 2

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { mustprogress uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #2 = { mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
attributes #3 = { nounwind }

!llvm.module.flags = !{!0, !1, !2, !3}
!llvm.ident = !{!4}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 8, !"PIC Level", i32 2}
!2 = !{i32 7, !"PIE Level", i32 2}
!3 = !{i32 7, !"uwtable", i32 2}
!4 = !{!"clang version 19.1.0 (git@github.com:llvm/llvm-project.git a4bf6cd7cfb1a1421ba92bca9d017b49936c55e4)"}
!5 = !{!6, !6, i64 0}
!6 = !{!"any pointer", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C++ TBAA"}
!9 = !{!10, !10, i64 0}
!10 = !{!"int", !7, i64 0}
!11 = !{!12, !6, i64 8}
!12 = !{!"_ZTSN10LinkedList4NodeIiEE", !10, i64 0, !6, i64 8}
!13 = distinct !{!13, !14}
!14 = !{!"llvm.loop.mustprogress"}
!15 = distinct !{!15, !14}
!16 = !{!12, !10, i64 0}


; Optimized IR (opt -passes='default<O3>'):
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

; Function Attrs: mustprogress nounwind uwtable
define dso_local noundef i32 @_Z35getNthFromEnd_UsingTwoPointerMethodPN10LinkedList10LinkedListIiEEi(ptr noundef nonnull %0, i32 noundef %1) local_unnamed_addr #0 {
  %3 = tail call noundef i32 @_ZN10LinkedList10LinkedListIiE9getLengthEv(ptr noundef nonnull align 8 dereferenceable(8) %0)
  %4 = tail call noundef ptr @_ZN10LinkedList10LinkedListIiE7getHeadEv(ptr noundef nonnull align 8 dereferenceable(8) %0)
  %5 = icmp slt i32 %3, %1
  %6 = icmp slt i32 %1, 1
  %or.cond = or i1 %6, %5
  br i1 %or.cond, label %37, label %.preheader21

.preheader21:                                     ; preds = %2
  %7 = icmp ugt i32 %1, 1
  br i1 %7, label %.lr.ph.preheader, label %.preheader

.lr.ph.preheader:                                 ; preds = %.preheader21
  %8 = add nsw i32 %1, -1
  %9 = add nsw i32 %1, -2
  %xtraiter = and i32 %8, 7
  %10 = icmp ult i32 %9, 7
  br i1 %10, label %.preheader.loopexit.unr-lcssa, label %.lr.ph.preheader.new

.lr.ph.preheader.new:                             ; preds = %.lr.ph.preheader
  %unroll_iter = and i32 %8, -8
  br label %.lr.ph

.preheader.loopexit.unr-lcssa:                    ; preds = %.lr.ph, %.lr.ph.preheader
  %.lcssa31.ph = phi ptr [ poison, %.lr.ph.preheader ], [ %30, %.lr.ph ]
  %.01622.unr = phi ptr [ %4, %.lr.ph.preheader ], [ %30, %.lr.ph ]
  %lcmp.mod.not = icmp eq i32 %xtraiter, 0
  br i1 %lcmp.mod.not, label %.preheader, label %.lr.ph.epil

.lr.ph.epil:                                      ; preds = %.preheader.loopexit.unr-lcssa, %.lr.ph.epil
  %.01622.epil = phi ptr [ %12, %.lr.ph.epil ], [ %.01622.unr, %.preheader.loopexit.unr-lcssa ]
  %epil.iter = phi i32 [ %epil.iter.next, %.lr.ph.epil ], [ 0, %.preheader.loopexit.unr-lcssa ]
  %11 = getelementptr inbounds i8, ptr %.01622.epil, i64 8
  %12 = load ptr, ptr %11, align 8, !tbaa !5
  %epil.iter.next = add i32 %epil.iter, 1
  %epil.iter.cmp.not = icmp eq i32 %epil.iter.next, %xtraiter
  br i1 %epil.iter.cmp.not, label %.preheader, label %.lr.ph.epil, !llvm.loop !11

.preheader:                                       ; preds = %.preheader.loopexit.unr-lcssa, %.lr.ph.epil, %.preheader21
  %.016.lcssa = phi ptr [ %4, %.preheader21 ], [ %.lcssa31.ph, %.preheader.loopexit.unr-lcssa ], [ %12, %.lr.ph.epil ]
  %13 = getelementptr inbounds i8, ptr %.016.lcssa, i64 8
  %14 = load ptr, ptr %13, align 8, !tbaa !5
  %.not24 = icmp eq ptr %14, null
  br i1 %.not24, label %._crit_edge, label %.lr.ph26

.lr.ph:                                           ; preds = %.lr.ph, %.lr.ph.preheader.new
  %.01622 = phi ptr [ %4, %.lr.ph.preheader.new ], [ %30, %.lr.ph ]
  %niter = phi i32 [ 0, %.lr.ph.preheader.new ], [ %niter.next.7, %.lr.ph ]
  %15 = getelementptr inbounds i8, ptr %.01622, i64 8
  %16 = load ptr, ptr %15, align 8, !tbaa !5
  %17 = getelementptr inbounds i8, ptr %16, i64 8
  %18 = load ptr, ptr %17, align 8, !tbaa !5
  %19 = getelementptr inbounds i8, ptr %18, i64 8
  %20 = load ptr, ptr %19, align 8, !tbaa !5
  %21 = getelementptr inbounds i8, ptr %20, i64 8
  %22 = load ptr, ptr %21, align 8, !tbaa !5
  %23 = getelementptr inbounds i8, ptr %22, i64 8
  %24 = load ptr, ptr %23, align 8, !tbaa !5
  %25 = getelementptr inbounds i8, ptr %24, i64 8
  %26 = load ptr, ptr %25, align 8, !tbaa !5
  %27 = getelementptr inbounds i8, ptr %26, i64 8
  %28 = load ptr, ptr %27, align 8, !tbaa !5
  %29 = getelementptr inbounds i8, ptr %28, i64 8
  %30 = load ptr, ptr %29, align 8, !tbaa !5
  %niter.next.7 = add i32 %niter, 8
  %niter.ncmp.7 = icmp eq i32 %niter.next.7, %unroll_iter
  br i1 %niter.ncmp.7, label %.preheader.loopexit.unr-lcssa, label %.lr.ph, !llvm.loop !13

.lr.ph26:                                         ; preds = %.preheader, %.lr.ph26
  %31 = phi ptr [ %35, %.lr.ph26 ], [ %14, %.preheader ]
  %.01725 = phi ptr [ %33, %.lr.ph26 ], [ %4, %.preheader ]
  %32 = getelementptr inbounds i8, ptr %.01725, i64 8
  %33 = load ptr, ptr %32, align 8, !tbaa !5
  %34 = getelementptr inbounds i8, ptr %31, i64 8
  %35 = load ptr, ptr %34, align 8, !tbaa !5
  %.not = icmp eq ptr %35, null
  br i1 %.not, label %._crit_edge, label %.lr.ph26, !llvm.loop !15

._crit_edge:                                      ; preds = %.lr.ph26, %.preheader
  %.017.lcssa = phi ptr [ %4, %.preheader ], [ %33, %.lr.ph26 ]
  %36 = load i32, ptr %.017.lcssa, align 8, !tbaa !16
  br label %37

37:                                               ; preds = %2, %._crit_edge
  %.018 = phi i32 [ %36, %._crit_edge ], [ -1, %2 ]
  ret i32 %.018
}

; Function Attrs: mustprogress nounwind uwtable
declare dso_local noundef i32 @_ZN10LinkedList10LinkedListIiE9getLengthEv(ptr noundef nonnull align 8 dereferenceable(8)) local_unnamed_addr #0 align 2

; Function Attrs: mustprogress nounwind uwtable
declare dso_local noundef ptr @_ZN10LinkedList10LinkedListIiE7getHeadEv(ptr noundef nonnull align 8 dereferenceable(8)) local_unnamed_addr #0 align 2

attributes #0 = { mustprogress nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }

!llvm.module.flags = !{!0, !1, !2, !3}
!llvm.ident = !{!4}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 8, !"PIC Level", i32 2}
!2 = !{i32 7, !"PIE Level", i32 2}
!3 = !{i32 7, !"uwtable", i32 2}
!4 = !{!"clang version 19.1.0 (git@github.com:llvm/llvm-project.git a4bf6cd7cfb1a1421ba92bca9d017b49936c55e4)"}
!5 = !{!6, !10, i64 8}
!6 = !{!"_ZTSN10LinkedList4NodeIiEE", !7, i64 0, !10, i64 8}
!7 = !{!"int", !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C++ TBAA"}
!10 = !{!"any pointer", !8, i64 0}
!11 = distinct !{!11, !12}
!12 = !{!"llvm.loop.unroll.disable"}
!13 = distinct !{!13, !14}
!14 = !{!"llvm.loop.mustprogress"}
!15 = distinct !{!15, !14}
!16 = !{!6, !7, i64 0}


; Effective O3 passes: CorrelatedValuePropagationPass,EarlyCSEPass,GVNPass,GlobalOptPass,IndVarSimplifyPass,InferFunctionAttrsPass,InstCombinePass,InstSimplifyPass,JumpThreadingPass,LCSSAPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,ReassociatePass,SROAPass,SimplifyCFGPass,TailCallElimPass