; LLVM IR from devparthgarg/Data-Structures-and-Algorithms :: 11. Linked List/26 Find Nth Node From End Of LL (26b 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 ptr, align 8
  store ptr %0, ptr %3, align 8, !tbaa !5
  store i32 %1, ptr %4, align 4, !tbaa !9
  %7 = load ptr, ptr %3, align 8, !tbaa !5
  %8 = load ptr, ptr %7, align 8, !tbaa !5
  %9 = icmp eq ptr %8, null
  br i1 %9, label %10, label %11

10:                                               ; preds = %2
  br label %46

11:                                               ; preds = %2
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #4
  %12 = load ptr, ptr %3, align 8, !tbaa !5
  %13 = load ptr, ptr %12, align 8, !tbaa !5
  store ptr %13, ptr %5, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %6) #4
  %14 = load ptr, ptr %3, align 8, !tbaa !5
  %15 = load ptr, ptr %14, align 8, !tbaa !5
  store ptr %15, ptr %6, align 8, !tbaa !5
  br label %16

16:                                               ; preds = %25, %11
  %17 = load i32, ptr %4, align 4, !tbaa !9
  %18 = add nsw i32 %17, -1
  store i32 %18, ptr %4, align 4, !tbaa !9
  %19 = icmp ne i32 %17, 0
  br i1 %19, label %20, label %23

20:                                               ; preds = %16
  %21 = load ptr, ptr %6, align 8, !tbaa !5
  %22 = icmp ne ptr %21, null
  br label %23

23:                                               ; preds = %20, %16
  %24 = phi i1 [ false, %16 ], [ %22, %20 ]
  br i1 %24, label %25, label %29

25:                                               ; preds = %23
  %26 = load ptr, ptr %6, align 8, !tbaa !5
  %27 = getelementptr inbounds %class.Node, ptr %26, i32 0, i32 1
  %28 = load ptr, ptr %27, align 8, !tbaa !11
  store ptr %28, ptr %6, align 8, !tbaa !5
  br label %16, !llvm.loop !13

29:                                               ; preds = %23
  br label %30

30:                                               ; preds = %33, %29
  %31 = load ptr, ptr %6, align 8, !tbaa !5
  %32 = icmp ne ptr %31, null
  br i1 %32, label %33, label %40

33:                                               ; preds = %30
  %34 = load ptr, ptr %5, align 8, !tbaa !5
  %35 = getelementptr inbounds %class.Node, ptr %34, i32 0, i32 1
  %36 = load ptr, ptr %35, align 8, !tbaa !11
  store ptr %36, ptr %5, align 8, !tbaa !5
  %37 = load ptr, ptr %6, align 8, !tbaa !5
  %38 = getelementptr inbounds %class.Node, ptr %37, i32 0, i32 1
  %39 = load ptr, ptr %38, align 8, !tbaa !11
  store ptr %39, ptr %6, align 8, !tbaa !5
  br label %30, !llvm.loop !15

40:                                               ; preds = %30
  %41 = load ptr, ptr %5, align 8, !tbaa !5
  %42 = getelementptr inbounds %class.Node, ptr %41, i32 0, i32 0
  %43 = load i32, ptr %42, align 8, !tbaa !16
  %44 = call noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEi(ptr noundef nonnull align 8 dereferenceable(8) @_ZSt4cout, i32 noundef %43)
  %45 = call noundef nonnull align 8 dereferenceable(8) ptr @_ZNSolsEPFRSoS_E(ptr noundef nonnull align 8 dereferenceable(8) %44, ptr noundef @_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_)
  call void @llvm.lifetime.end.p0(i64 8, ptr %6) #4
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #4
  br label %46

46:                                               ; preds = %40, %10
  ret void
}

; 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 %.preheader12

.preheader12:                                     ; preds = %2
  %.not20 = icmp eq i32 %1, 0
  br i1 %.not20, label %.lr.ph18.preheader, label %.lr.ph

.preheader:                                       ; preds = %.lr.ph
  %.not15 = icmp eq ptr %7, null
  br i1 %.not15, label %._crit_edge, label %.lr.ph18.preheader

.lr.ph18.preheader:                               ; preds = %.preheader12, %.preheader
  %.117.ph = phi ptr [ %3, %.preheader12 ], [ %7, %.preheader ]
  br label %.lr.ph18

.lr.ph:                                           ; preds = %.preheader12, %.lr.ph
  %.014 = phi ptr [ %7, %.lr.ph ], [ %3, %.preheader12 ]
  %.01013 = phi i32 [ %5, %.lr.ph ], [ %1, %.preheader12 ]
  %5 = add nsw i32 %.01013, -1
  %6 = getelementptr inbounds i8, ptr %.014, i64 8
  %7 = load ptr, ptr %6, align 8, !tbaa !9
  %8 = icmp ne i32 %5, 0
  %9 = icmp ne ptr %7, null
  %10 = select i1 %8, i1 %9, i1 false
  br i1 %10, label %.lr.ph, label %.preheader, !llvm.loop !12

.lr.ph18:                                         ; preds = %.lr.ph18.preheader, %.lr.ph18
  %.117 = phi ptr [ %14, %.lr.ph18 ], [ %.117.ph, %.lr.ph18.preheader ]
  %.0916 = phi ptr [ %12, %.lr.ph18 ], [ %3, %.lr.ph18.preheader ]
  %11 = getelementptr inbounds i8, ptr %.0916, i64 8
  %12 = load ptr, ptr %11, align 8, !tbaa !9
  %13 = getelementptr inbounds i8, ptr %.117, i64 8
  %14 = load ptr, ptr %13, align 8, !tbaa !9
  %.not = icmp eq ptr %14, null
  br i1 %.not, label %._crit_edge, label %.lr.ph18, !llvm.loop !14

._crit_edge:                                      ; preds = %.lr.ph18, %.preheader
  %.09.lcssa = phi ptr [ %3, %.preheader ], [ %12, %.lr.ph18 ]
  %15 = load i32, ptr %.09.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 = %2, %._crit_edge
  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: CorrelatedValuePropagationPass,EarlyCSEPass,GVNPass,GlobalOptPass,InferFunctionAttrsPass,InstCombinePass,InstSimplifyPass,JumpThreadingPass,LCSSAPass,LoopRotatePass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass