; LLVM IR from sbshah97/DS-Algo-Handbook :: Data-Structures/Linked_List/Doubly_Linked_List/doubly-linkedlist.ll (Z11reverselistP4node)

; 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 }
%struct.node = type { ptr, ptr, i32 }

@_ZSt4cout = external global %"class.std::basic_ostream", align 8
@.str = external hidden unnamed_addr constant [15 x i8], align 1
@.str.12 = external hidden unnamed_addr constant [19 x i8], align 1

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

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

; Function Attrs: inlinehint mustprogress uwtable
declare noundef nonnull align 8 dereferenceable(8) ptr @_ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc(ptr noundef nonnull align 8 dereferenceable(8), ptr noundef) #1

; Function Attrs: mustprogress uwtable
define dso_local noundef ptr @_Z11reverselistP4node(ptr noundef %0) #2 {
  %2 = alloca ptr, align 8
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  %5 = alloca ptr, align 8
  store ptr %0, ptr %3, align 8, !tbaa !5
  %6 = load ptr, ptr %3, align 8, !tbaa !5
  %7 = icmp eq ptr %6, null
  br i1 %7, label %8, label %11

8:                                                ; preds = %1
  %9 = call noundef nonnull align 8 dereferenceable(8) ptr @_ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc(ptr noundef nonnull align 8 dereferenceable(8) @_ZSt4cout, ptr noundef @.str)
  %10 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %10, ptr %2, align 8
  br label %41

11:                                               ; preds = %1
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #3
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #3
  %12 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %12, ptr %4, align 8, !tbaa !5
  %13 = load ptr, ptr %4, align 8, !tbaa !5
  %14 = getelementptr inbounds %struct.node, ptr %13, i32 0, i32 1
  %15 = load ptr, ptr %14, align 8, !tbaa !9
  store ptr %15, ptr %5, align 8, !tbaa !5
  %16 = load ptr, ptr %4, align 8, !tbaa !5
  %17 = getelementptr inbounds %struct.node, ptr %16, i32 0, i32 1
  store ptr null, ptr %17, align 8, !tbaa !9
  %18 = load ptr, ptr %5, align 8, !tbaa !5
  %19 = load ptr, ptr %4, align 8, !tbaa !5
  %20 = getelementptr inbounds %struct.node, ptr %19, i32 0, i32 0
  store ptr %18, ptr %20, align 8, !tbaa !12
  br label %21

21:                                               ; preds = %24, %11
  %22 = load ptr, ptr %5, align 8, !tbaa !5
  %23 = icmp ne ptr %22, null
  br i1 %23, label %24, label %37

24:                                               ; preds = %21
  %25 = load ptr, ptr %5, align 8, !tbaa !5
  %26 = getelementptr inbounds %struct.node, ptr %25, i32 0, i32 1
  %27 = load ptr, ptr %26, align 8, !tbaa !9
  %28 = load ptr, ptr %5, align 8, !tbaa !5
  %29 = getelementptr inbounds %struct.node, ptr %28, i32 0, i32 0
  store ptr %27, ptr %29, align 8, !tbaa !12
  %30 = load ptr, ptr %4, align 8, !tbaa !5
  %31 = load ptr, ptr %5, align 8, !tbaa !5
  %32 = getelementptr inbounds %struct.node, ptr %31, i32 0, i32 1
  store ptr %30, ptr %32, align 8, !tbaa !9
  %33 = load ptr, ptr %5, align 8, !tbaa !5
  store ptr %33, ptr %4, align 8, !tbaa !5
  %34 = load ptr, ptr %5, align 8, !tbaa !5
  %35 = getelementptr inbounds %struct.node, ptr %34, i32 0, i32 0
  %36 = load ptr, ptr %35, align 8, !tbaa !12
  store ptr %36, ptr %5, align 8, !tbaa !5
  br label %21, !llvm.loop !13

37:                                               ; preds = %21
  %38 = load ptr, ptr %4, align 8, !tbaa !5
  store ptr %38, ptr %3, align 8, !tbaa !5
  %39 = call noundef nonnull align 8 dereferenceable(8) ptr @_ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc(ptr noundef nonnull align 8 dereferenceable(8) @_ZSt4cout, ptr noundef @.str.12)
  %40 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %40, ptr %2, align 8
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #3
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #3
  br label %41

41:                                               ; preds = %37, %8
  %42 = load ptr, ptr %2, align 8
  ret ptr %42
}

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { 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 #2 = { 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 #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, !6, i64 8}
!10 = !{!"_ZTS4node", !6, i64 0, !6, i64 8, !11, i64 16}
!11 = !{!"int", !7, i64 0}
!12 = !{!10, !6, i64 0}
!13 = distinct !{!13, !14}
!14 = !{!"llvm.loop.mustprogress"}


; 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
@.str = external hidden unnamed_addr constant [15 x i8], align 1
@.str.12 = external hidden unnamed_addr constant [19 x i8], align 1

; Function Attrs: inlinehint mustprogress uwtable
declare noundef nonnull align 8 dereferenceable(8) ptr @_ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc(ptr noundef nonnull align 8 dereferenceable(8), ptr noundef) local_unnamed_addr #0

; Function Attrs: mustprogress uwtable
define dso_local noundef ptr @_Z11reverselistP4node(ptr noundef %0) local_unnamed_addr #1 {
  %2 = icmp eq ptr %0, null
  br i1 %2, label %._crit_edge, label %3

3:                                                ; preds = %1
  %4 = getelementptr inbounds i8, ptr %0, i64 8
  %5 = load ptr, ptr %4, align 8, !tbaa !5
  store ptr null, ptr %4, align 8, !tbaa !5
  store ptr %5, ptr %0, align 8, !tbaa !11
  %.not20 = icmp eq ptr %5, null
  br i1 %.not20, label %._crit_edge, label %.lr.ph

.lr.ph:                                           ; preds = %3, %.lr.ph
  %.022 = phi ptr [ %7, %.lr.ph ], [ %5, %3 ]
  %.01721 = phi ptr [ %.022, %.lr.ph ], [ %0, %3 ]
  %6 = getelementptr inbounds i8, ptr %.022, i64 8
  %7 = load ptr, ptr %6, align 8, !tbaa !5
  store ptr %7, ptr %.022, align 8, !tbaa !11
  store ptr %.01721, ptr %6, align 8, !tbaa !5
  %.not = icmp eq ptr %7, null
  br i1 %.not, label %._crit_edge, label %.lr.ph, !llvm.loop !12

._crit_edge:                                      ; preds = %.lr.ph, %3, %1
  %.str.12.sink = phi ptr [ @.str, %1 ], [ @.str.12, %3 ], [ @.str.12, %.lr.ph ]
  %.018 = phi ptr [ null, %1 ], [ %0, %3 ], [ %.022, %.lr.ph ]
  %8 = tail call noundef nonnull align 8 dereferenceable(8) ptr @_ZStlsISt11char_traitsIcEERSt13basic_ostreamIcT_ES5_PKc(ptr noundef nonnull align 8 dereferenceable(8) @_ZSt4cout, ptr noundef nonnull %.str.12.sink)
  ret ptr %.018
}

attributes #0 = { 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 #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" }

!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, !7, i64 8}
!6 = !{!"_ZTS4node", !7, i64 0, !7, i64 8, !10, i64 16}
!7 = !{!"any pointer", !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C++ TBAA"}
!10 = !{!"int", !8, i64 0}
!11 = !{!6, !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"llvm.loop.mustprogress"}


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