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

; 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 @_Z26findMiddle_UsingTwoPointerPN10LinkedList10LinkedListIiEE(ptr noundef %0) #1 {
  %2 = alloca i32, align 4
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  %5 = alloca ptr, align 8
  %6 = alloca ptr, align 8
  %7 = alloca i32, align 4
  store ptr %0, ptr %3, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #3
  %8 = load ptr, ptr %3, align 8, !tbaa !5
  %9 = call noundef ptr @_ZN10LinkedList10LinkedListIiE7getHeadEv(ptr noundef nonnull align 8 dereferenceable(8) %8)
  store ptr %9, ptr %4, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #3
  %10 = load ptr, ptr %4, align 8, !tbaa !5
  store ptr %10, ptr %5, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %6) #3
  %11 = load ptr, ptr %4, align 8, !tbaa !5
  store ptr %11, ptr %6, align 8, !tbaa !5
  %12 = load ptr, ptr %6, align 8, !tbaa !5
  %13 = icmp eq ptr %12, null
  br i1 %13, label %14, label %15

14:                                               ; preds = %1
  store i32 -1, ptr %2, align 4
  store i32 1, ptr %7, align 4
  br label %39

15:                                               ; preds = %1
  br label %16

16:                                               ; preds = %26, %15
  %17 = load ptr, ptr %5, align 8, !tbaa !5
  %18 = icmp ne ptr %17, null
  br i1 %18, label %19, label %24

19:                                               ; preds = %16
  %20 = load ptr, ptr %5, align 8, !tbaa !5
  %21 = getelementptr inbounds %"struct.LinkedList::Node", ptr %20, i32 0, i32 1
  %22 = load ptr, ptr %21, align 8, !tbaa !9
  %23 = icmp ne ptr %22, null
  br label %24

24:                                               ; preds = %19, %16
  %25 = phi i1 [ false, %16 ], [ %23, %19 ]
  br i1 %25, label %26, label %35

26:                                               ; preds = %24
  %27 = load ptr, ptr %5, align 8, !tbaa !5
  %28 = getelementptr inbounds %"struct.LinkedList::Node", ptr %27, i32 0, i32 1
  %29 = load ptr, ptr %28, align 8, !tbaa !9
  %30 = getelementptr inbounds %"struct.LinkedList::Node", ptr %29, i32 0, i32 1
  %31 = load ptr, ptr %30, align 8, !tbaa !9
  store ptr %31, ptr %5, align 8, !tbaa !5
  %32 = load ptr, ptr %6, align 8, !tbaa !5
  %33 = getelementptr inbounds %"struct.LinkedList::Node", ptr %32, i32 0, i32 1
  %34 = load ptr, ptr %33, align 8, !tbaa !9
  store ptr %34, ptr %6, align 8, !tbaa !5
  br label %16, !llvm.loop !12

35:                                               ; preds = %24
  %36 = load ptr, ptr %6, align 8, !tbaa !5
  %37 = getelementptr inbounds %"struct.LinkedList::Node", ptr %36, i32 0, i32 0
  %38 = load i32, ptr %37, align 8, !tbaa !14
  store i32 %38, ptr %2, align 4
  store i32 1, ptr %7, align 4
  br label %39

39:                                               ; preds = %35, %14
  call void @llvm.lifetime.end.p0(i64 8, ptr %6) #3
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #3
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #3
  %40 = load i32, ptr %2, align 4
  ret i32 %40
}

; 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 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, !6, i64 8}
!10 = !{!"_ZTSN10LinkedList4NodeIiEE", !11, i64 0, !6, i64 8}
!11 = !{!"int", !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"llvm.loop.mustprogress"}
!14 = !{!10, !11, 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 @_Z26findMiddle_UsingTwoPointerPN10LinkedList10LinkedListIiEE(ptr noundef nonnull %0) local_unnamed_addr #0 {
  %2 = tail call noundef ptr @_ZN10LinkedList10LinkedListIiE7getHeadEv(ptr noundef nonnull align 8 dereferenceable(8) %0)
  %3 = icmp eq ptr %2, null
  br i1 %3, label %12, label %.preheader

.preheader:                                       ; preds = %1, %6
  %.015 = phi ptr [ %10, %6 ], [ %2, %1 ]
  %.0914 = phi ptr [ %8, %6 ], [ %2, %1 ]
  %4 = getelementptr inbounds i8, ptr %.0914, i64 8
  %5 = load ptr, ptr %4, align 8, !tbaa !5
  %.not13 = icmp eq ptr %5, null
  br i1 %.not13, label %.critedge, label %6

6:                                                ; preds = %.preheader
  %7 = getelementptr inbounds i8, ptr %5, i64 8
  %8 = load ptr, ptr %7, align 8, !tbaa !5
  %9 = getelementptr inbounds i8, ptr %.015, i64 8
  %10 = load ptr, ptr %9, align 8, !tbaa !5
  %.not = icmp eq ptr %8, null
  br i1 %.not, label %.critedge, label %.preheader, !llvm.loop !11

.critedge:                                        ; preds = %6, %.preheader
  %.0.lcssa = phi ptr [ %10, %6 ], [ %.015, %.preheader ]
  %11 = load i32, ptr %.0.lcssa, align 8, !tbaa !13
  br label %12

12:                                               ; preds = %1, %.critedge
  %.010 = phi i32 [ %11, %.critedge ], [ -1, %1 ]
  ret i32 %.010
}

; 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.mustprogress"}
!13 = !{!6, !7, i64 0}


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