; LLVM IR from codemistic/Data-Structures-and-Algorithms :: CPP/LINKED LIST/DOUBLY LINKED LIST/middleoflinkedlist.ll (Z9approach2P4node)

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

; Function Attrs: mustprogress nounwind uwtable
define dso_local noundef ptr @_Z9approach2P4node(ptr noundef %0) #1 {
  %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 %13, label %8

8:                                                ; preds = %1
  %9 = load ptr, ptr %3, align 8, !tbaa !5
  %10 = getelementptr inbounds %class.node, ptr %9, i32 0, i32 1
  %11 = load ptr, ptr %10, align 8, !tbaa !9
  %12 = icmp eq ptr %11, null
  br i1 %12, label %13, label %15

13:                                               ; preds = %8, %1
  %14 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %14, ptr %2, align 8
  br label %52

15:                                               ; preds = %8
  %16 = load ptr, ptr %3, align 8, !tbaa !5
  %17 = getelementptr inbounds %class.node, ptr %16, i32 0, i32 1
  %18 = load ptr, ptr %17, align 8, !tbaa !9
  %19 = getelementptr inbounds %class.node, ptr %18, i32 0, i32 1
  %20 = load ptr, ptr %19, align 8, !tbaa !9
  %21 = icmp eq ptr %20, null
  br i1 %21, label %22, label %26

22:                                               ; preds = %15
  %23 = load ptr, ptr %3, align 8, !tbaa !5
  %24 = getelementptr inbounds %class.node, ptr %23, i32 0, i32 1
  %25 = load ptr, ptr %24, align 8, !tbaa !9
  store ptr %25, ptr %2, align 8
  br label %52

26:                                               ; preds = %15
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  %27 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %27, ptr %4, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #2
  %28 = load ptr, ptr %3, align 8, !tbaa !5
  %29 = getelementptr inbounds %class.node, ptr %28, i32 0, i32 1
  %30 = load ptr, ptr %29, align 8, !tbaa !9
  store ptr %30, ptr %5, align 8, !tbaa !5
  br label %31

31:                                               ; preds = %46, %26
  %32 = load ptr, ptr %5, align 8, !tbaa !5
  %33 = icmp ne ptr %32, null
  br i1 %33, label %34, label %50

34:                                               ; preds = %31
  %35 = load ptr, ptr %5, align 8, !tbaa !5
  %36 = getelementptr inbounds %class.node, ptr %35, i32 0, i32 1
  %37 = load ptr, ptr %36, align 8, !tbaa !9
  store ptr %37, ptr %5, align 8, !tbaa !5
  %38 = load ptr, ptr %5, align 8, !tbaa !5
  %39 = getelementptr inbounds %class.node, ptr %38, i32 0, i32 1
  %40 = load ptr, ptr %39, align 8, !tbaa !9
  %41 = icmp eq ptr %40, null
  br i1 %41, label %42, label %46

42:                                               ; preds = %34
  %43 = load ptr, ptr %5, align 8, !tbaa !5
  %44 = getelementptr inbounds %class.node, ptr %43, i32 0, i32 1
  %45 = load ptr, ptr %44, align 8, !tbaa !9
  store ptr %45, ptr %5, align 8, !tbaa !5
  br label %46

46:                                               ; preds = %42, %34
  %47 = load ptr, ptr %4, align 8, !tbaa !5
  %48 = getelementptr inbounds %class.node, ptr %47, i32 0, i32 1
  %49 = load ptr, ptr %48, align 8, !tbaa !9
  store ptr %49, ptr %4, align 8, !tbaa !5
  br label %31, !llvm.loop !12

50:                                               ; preds = %31
  %51 = load ptr, ptr %4, align 8, !tbaa !5
  store ptr %51, ptr %2, align 8
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #2
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #2
  br label %52

52:                                               ; preds = %50, %22, %13
  %53 = load ptr, ptr %2, align 8
  ret ptr %53
}

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { 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 #2 = { 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", !11, i64 0, !6, i64 8}
!11 = !{!"int", !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"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"

; Function Attrs: mustprogress nofree norecurse nosync nounwind willreturn memory(read, inaccessiblemem: none) uwtable
define dso_local noundef ptr @_Z9approach2P4node(ptr noundef readonly %0) local_unnamed_addr #0 {
  %2 = icmp eq ptr %0, null
  br i1 %2, label %.loopexit, label %3

3:                                                ; preds = %1
  %4 = getelementptr inbounds i8, ptr %0, i64 8
  %5 = load ptr, ptr %4, align 8, !tbaa !5
  %6 = icmp eq ptr %5, null
  br i1 %6, label %.loopexit, label %7

7:                                                ; preds = %3
  %8 = getelementptr inbounds i8, ptr %5, i64 8
  %9 = load ptr, ptr %8, align 8, !tbaa !5
  %10 = icmp eq ptr %9, null
  br i1 %10, label %.loopexit, label %select.unfold

select.unfold:                                    ; preds = %7, %select.unfold
  %.020 = phi ptr [ %12, %select.unfold ], [ %5, %7 ]
  %.01419 = phi ptr [ %17, %select.unfold ], [ %0, %7 ]
  %11 = getelementptr inbounds i8, ptr %.020, i64 8
  %12 = load ptr, ptr %11, align 8, !tbaa !5
  %13 = getelementptr inbounds i8, ptr %12, i64 8
  %14 = load ptr, ptr %13, align 8, !tbaa !5
  %15 = icmp eq ptr %14, null
  %16 = getelementptr inbounds i8, ptr %.01419, i64 8
  %17 = load ptr, ptr %16, align 8, !tbaa !5
  %.not21 = icmp eq ptr %12, null
  %.not = or i1 %15, %.not21
  br i1 %.not, label %.loopexit, label %select.unfold

.loopexit:                                        ; preds = %select.unfold, %7, %1, %3
  %.015 = phi ptr [ %0, %3 ], [ null, %1 ], [ %5, %7 ], [ %17, %select.unfold ]
  ret ptr %.015
}

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(read, inaccessiblemem: none) 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 = !{!"_ZTS4node", !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}


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