; LLVM IR from devparthgarg/Data-Structures-and-Algorithms :: 11. Linked List/26 Find Nth Node From End Of LL (26a Find Nth Node From End Of LL)

; 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"

%"class.std::basic_ostream" = type { ptr, %"class.std::basic_ios" }
%"class.std::basic_ios" = type { %"class.std::ios_base", ptr, i8, i8, ptr, ptr, ptr, ptr }
%"class.std::ios_base" = type { ptr, i64, i64, i32, i32, i32, ptr, %"struct.std::ios_base::_Words", [8 x %"struct.std::ios_base::_Words"], i32, ptr, %"class.std::locale" }
%"struct.std::ios_base::_Words" = type { ptr, i64 }
%"class.std::locale" = type { ptr }
%class.Node = type { i32, ptr }

@_ZSt4cout = external global %"class.std::basic_ostream", align 8

; Function Attrs: mustprogress uwtable
define dso_local void @_Z7NthNodeRP4Nodei(ptr noundef nonnull align 8 dereferenceable(8) %0, i32 noundef %1) #0 {
  %3 = alloca ptr, align 8
  %4 = alloca i32, align 4
  %5 = alloca ptr, align 8
  %6 = alloca i32, align 4
  %7 = alloca i32, align 4
  %8 = alloca i32, align 4
  store ptr %0, ptr %3, align 8, !tbaa !5
  store i32 %1, ptr %4, align 4, !tbaa !9
  %9 = load ptr, ptr %3, align 8, !tbaa !5
  %10 = load ptr, ptr %9, align 8, !tbaa !5
  %11 = icmp eq ptr %10, null
  br i1 %11, label %12, label %13

12:                                               ; preds = %2
  br label %58

13:                                               ; preds = %2
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #4
  %14 = load ptr, ptr %3, align 8, !tbaa !5
  %15 = load ptr, ptr %14, align 8, !tbaa !5
  store ptr %15, ptr %5, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 4, ptr %6) #4
  store i32 0, ptr %6, align 4, !tbaa !9
  br label %16

16:                                               ; preds = %19, %13
  %17 = load ptr, ptr %5, align 8, !tbaa !5
  %18 = icmp ne ptr %17, null
  br i1 %18, label %19, label %25

19:                                               ; preds = %16
  %20 = load ptr, ptr %5, align 8, !tbaa !5
  %21 = getelementptr inbounds %class.Node, ptr %20, i32 0, i32 1
  %22 = load ptr, ptr %21, align 8, !tbaa !11
  store ptr %22, ptr %5, align 8, !tbaa !5
  %23 = load i32, ptr %6, align 4, !tbaa !9
  %24 = add nsw i32 %23, 1
  store i32 %24, ptr %6, align 4, !tbaa !9
  br label %16, !llvm.loop !13

25:                                               ; preds = %16
  %26 = load i32, ptr %6, align 4, !tbaa !9
  %27 = load i32, ptr %4, align 4, !tbaa !9
  %28 = icmp slt i32 %26, %27
  br i1 %28, label %29, label %30

29:                                               ; preds = %25
  store i32 1, ptr %7, align 4
  br label %56

30:                                               ; preds = %25
  call void @llvm.lifetime.start.p0(i64 4, ptr %8) #4
  store i32 0, ptr %8, align 4, !tbaa !9
  %31 = load ptr, ptr %3, align 8, !tbaa !5
  %32 = load ptr, ptr %31, align 8, !tbaa !5
  store ptr %32, ptr %5, align 8, !tbaa !5
  br label %33

33:                                               ; preds = %44, %30
  %34 = load ptr, ptr %5, align 8, !tbaa !5
  %35 = icmp ne ptr %34, null
  br i1 %35, label %36, label %42

36:                                               ; preds = %33
  %37 = load i32, ptr %8, align 4, !tbaa !9
  %38 = load i32, ptr %6, align 4, !tbaa !9
  %39 = load i32, ptr %4, align 4, !tbaa !9
  %40 = sub nsw i32 %38, %39
  %41 = icmp slt i32 %37, %40
  br label %42

42:                                               ; preds = %36, %33
  %43 = phi i1 [ false, %33 ], [ %41, %36 ]
  br i1 %43, label %44, label %50

44:                                               ; preds = %42
  %45 = load ptr, ptr %5, align 8, !tbaa !5
  %46 = getelementptr inbounds %class.Node, ptr %45, i32 0, i32 1
  %47 = load ptr, ptr %46, align 8, !tbaa !11
  store ptr %47, ptr %5, align 8, !tbaa !5
  %48 = load i32, ptr %8, align 4, !tbaa !9
  %49 = add nsw i32 %48, 1
  store i32 %49, ptr %8, align 4, !tbaa !9
  br label %33, !llvm.loop !15

50:                                               ; preds = %42
  %51 = load ptr, ptr %5, align 8, !tbaa !5
  %52 = getelementptr inbounds %class.Node, ptr %51, i32 0, i32 0
  %53 = load i32, ptr %52, align 8, !tbaa !16
  %54 = call noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEi(ptr noundef nonnull align 8 dereferenceable(8) @_ZSt4cout, i32 noundef %53)
  %55 = call noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEPFRSoS_E(ptr noundef nonnull align 8 dereferenceable(8) %54, ptr noundef @_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_)
  call void @llvm.lifetime.end.p0(i64 4, ptr %8) #4
  store i32 0, ptr %7, align 4
  br label %56

56:                                               ; preds = %50, %29
  call void @llvm.lifetime.end.p0(i64 4, ptr %6) #4
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #4
  %57 = load i32, ptr %7, align 4
  switch i32 %57, label %59 [
    i32 0, label %58
    i32 1, label %58
  ]

58:                                               ; preds = %56, %56, %12
  ret void

59:                                               ; preds = %56
  unreachable
}

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #1

declare noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEi(ptr noundef nonnull align 8 dereferenceable(8), i32 noundef) #2

; Function Attrs: mustprogress uwtable
declare noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEPFRSoS_E(ptr noundef nonnull align 8 dereferenceable(8), ptr noundef) #0 align 2

; Function Attrs: inlinehint mustprogress uwtable
declare noundef nonnull align 8 dereferenceable(8) ptr @_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_(ptr noundef nonnull align 8 dereferenceable(8)) #3

; Function Attrs: nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #1

attributes #0 = { 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 #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #2 = { "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 = { inlinehint 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 #4 = { 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 = !{!"_ZTS4Node", !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"

%"class.std::basic_ostream" = type { ptr, %"class.std::basic_ios" }
%"class.std::basic_ios" = type { %"class.std::ios_base", ptr, i8, i8, ptr, ptr, ptr, ptr }
%"class.std::ios_base" = type { ptr, i64, i64, i32, i32, i32, ptr, %"struct.std::ios_base::_Words", [8 x %"struct.std::ios_base::_Words"], i32, ptr, %"class.std::locale" }
%"struct.std::ios_base::_Words" = type { ptr, i64 }
%"class.std::locale" = type { ptr }

@_ZSt4cout = external global %"class.std::basic_ostream", align 8

; Function Attrs: mustprogress uwtable
define dso_local void @_Z7NthNodeRP4Nodei(ptr nocapture noundef nonnull readonly align 8 dereferenceable(8) %0, i32 noundef %1) local_unnamed_addr #0 {
  %3 = load ptr, ptr %0, align 8, !tbaa !5
  %4 = icmp eq ptr %3, null
  br i1 %4, label %18, label %.preheader20

.preheader20:                                     ; preds = %2, %.preheader20
  %.01422 = phi i32 [ %7, %.preheader20 ], [ 0, %2 ]
  %.01521 = phi ptr [ %6, %.preheader20 ], [ %3, %2 ]
  %5 = getelementptr inbounds i8, ptr %.01521, i64 8
  %6 = load ptr, ptr %5, align 8, !tbaa !9
  %7 = add nuw nsw i32 %.01422, 1
  %.not = icmp eq ptr %6, null
  br i1 %.not, label %8, label %.preheader20, !llvm.loop !12

8:                                                ; preds = %.preheader20
  %9 = icmp slt i32 %7, %1
  br i1 %9, label %18, label %.preheader

.preheader:                                       ; preds = %8
  %10 = sub nsw i32 %7, %1
  %11 = icmp sgt i32 %10, 0
  br i1 %11, label %.lr.ph, label %.critedge

.lr.ph:                                           ; preds = %.preheader, %.lr.ph
  %.127 = phi ptr [ %.1, %.lr.ph ], [ %3, %.preheader ]
  %.026 = phi i32 [ %13, %.lr.ph ], [ 0, %.preheader ]
  %12 = getelementptr inbounds i8, ptr %.127, i64 8
  %13 = add nuw nsw i32 %.026, 1
  %.1 = load ptr, ptr %12, align 8, !tbaa !5
  %.not18 = icmp ne ptr %.1, null
  %14 = icmp slt i32 %13, %10
  %or.cond = select i1 %.not18, i1 %14, i1 false
  br i1 %or.cond, label %.lr.ph, label %.critedge, !llvm.loop !14

.critedge:                                        ; preds = %.lr.ph, %.preheader
  %.1.lcssa = phi ptr [ %3, %.preheader ], [ %.1, %.lr.ph ]
  %15 = load i32, ptr %.1.lcssa, align 8, !tbaa !15
  %16 = tail call noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEi(ptr noundef nonnull align 8 dereferenceable(8) @_ZSt4cout, i32 noundef %15)
  %17 = tail call noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEPFRSoS_E(ptr noundef nonnull align 8 dereferenceable(8) %16, ptr noundef nonnull @_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_)
  br label %18

18:                                               ; preds = %.critedge, %8, %2
  ret void
}

declare noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEi(ptr noundef nonnull align 8 dereferenceable(8), i32 noundef) local_unnamed_addr #1

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

; Function Attrs: inlinehint mustprogress uwtable
declare noundef nonnull align 8 dereferenceable(8) ptr @_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_(ptr noundef nonnull align 8 dereferenceable(8)) #2

attributes #0 = { 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 #1 = { "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 = { inlinehint 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" }

!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, !6, i64 8}
!10 = !{!"_ZTS4Node", !11, i64 0, !6, i64 8}
!11 = !{!"int", !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"llvm.loop.mustprogress"}
!14 = distinct !{!14, !13}
!15 = !{!10, !11, i64 0}


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