; LLVM IR from JessonYue/LeetCodeLearning :: Array/yangxin/第四周练习6-22/面试题 02.08. 环路检测 (link)

; 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.ListNode = type { i32, ptr }

; Function Attrs: nounwind uwtable
define dso_local ptr @detectCycle(ptr noundef %0) #0 {
  %2 = alloca ptr, align 8
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  %5 = alloca ptr, align 8
  %6 = alloca i32, align 4
  store ptr %0, ptr %3, align 8, !tbaa !5
  %7 = load ptr, ptr %3, align 8, !tbaa !5
  %8 = icmp eq ptr %7, null
  br i1 %8, label %14, label %9

9:                                                ; preds = %1
  %10 = load ptr, ptr %3, align 8, !tbaa !5
  %11 = getelementptr inbounds %struct.ListNode, ptr %10, i32 0, i32 1
  %12 = load ptr, ptr %11, align 8, !tbaa !9
  %13 = icmp eq ptr %12, null
  br i1 %13, label %14, label %15

14:                                               ; preds = %9, %1
  store ptr null, ptr %2, align 8
  br label %67

15:                                               ; preds = %9
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  %16 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %16, ptr %4, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #2
  %17 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %17, ptr %5, align 8, !tbaa !5
  br label %18

18:                                               ; preds = %41, %15
  %19 = load ptr, ptr %4, align 8, !tbaa !5
  %20 = icmp ne ptr %19, null
  br i1 %20, label %21, label %26

21:                                               ; preds = %18
  %22 = load ptr, ptr %4, align 8, !tbaa !5
  %23 = getelementptr inbounds %struct.ListNode, ptr %22, i32 0, i32 1
  %24 = load ptr, ptr %23, align 8, !tbaa !9
  %25 = icmp ne ptr %24, null
  br label %26

26:                                               ; preds = %21, %18
  %27 = phi i1 [ false, %18 ], [ %25, %21 ]
  br i1 %27, label %28, label %42

28:                                               ; preds = %26
  %29 = load ptr, ptr %4, align 8, !tbaa !5
  %30 = getelementptr inbounds %struct.ListNode, ptr %29, i32 0, i32 1
  %31 = load ptr, ptr %30, align 8, !tbaa !9
  %32 = getelementptr inbounds %struct.ListNode, ptr %31, i32 0, i32 1
  %33 = load ptr, ptr %32, align 8, !tbaa !9
  store ptr %33, ptr %4, align 8, !tbaa !5
  %34 = load ptr, ptr %5, align 8, !tbaa !5
  %35 = getelementptr inbounds %struct.ListNode, ptr %34, i32 0, i32 1
  %36 = load ptr, ptr %35, align 8, !tbaa !9
  store ptr %36, ptr %5, align 8, !tbaa !5
  %37 = load ptr, ptr %4, align 8, !tbaa !5
  %38 = load ptr, ptr %5, align 8, !tbaa !5
  %39 = icmp eq ptr %37, %38
  br i1 %39, label %40, label %41

40:                                               ; preds = %28
  br label %42

41:                                               ; preds = %28
  br label %18, !llvm.loop !12

42:                                               ; preds = %40, %26
  %43 = load ptr, ptr %4, align 8, !tbaa !5
  %44 = icmp eq ptr %43, null
  br i1 %44, label %50, label %45

45:                                               ; preds = %42
  %46 = load ptr, ptr %4, align 8, !tbaa !5
  %47 = getelementptr inbounds %struct.ListNode, ptr %46, i32 0, i32 1
  %48 = load ptr, ptr %47, align 8, !tbaa !9
  %49 = icmp eq ptr %48, null
  br i1 %49, label %50, label %51

50:                                               ; preds = %45, %42
  store ptr null, ptr %2, align 8
  store i32 1, ptr %6, align 4
  br label %66

51:                                               ; preds = %45
  %52 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %52, ptr %4, align 8, !tbaa !5
  br label %53

53:                                               ; preds = %57, %51
  %54 = load ptr, ptr %4, align 8, !tbaa !5
  %55 = load ptr, ptr %5, align 8, !tbaa !5
  %56 = icmp ne ptr %54, %55
  br i1 %56, label %57, label %64

57:                                               ; preds = %53
  %58 = load ptr, ptr %4, align 8, !tbaa !5
  %59 = getelementptr inbounds %struct.ListNode, ptr %58, i32 0, i32 1
  %60 = load ptr, ptr %59, align 8, !tbaa !9
  store ptr %60, ptr %4, align 8, !tbaa !5
  %61 = load ptr, ptr %5, align 8, !tbaa !5
  %62 = getelementptr inbounds %struct.ListNode, ptr %61, i32 0, i32 1
  %63 = load ptr, ptr %62, align 8, !tbaa !9
  store ptr %63, ptr %5, align 8, !tbaa !5
  br label %53, !llvm.loop !14

64:                                               ; preds = %53
  %65 = load ptr, ptr %4, align 8, !tbaa !5
  store ptr %65, ptr %2, align 8
  store i32 1, ptr %6, align 4
  br label %66

66:                                               ; preds = %64, %50
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #2
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #2
  br label %67

67:                                               ; preds = %66, %14
  %68 = load ptr, ptr %2, align 8
  ret ptr %68
}

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

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

attributes #0 = { 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 #1 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
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/C++ TBAA"}
!9 = !{!10, !6, i64 8}
!10 = !{!"ListNode", !11, i64 0, !6, i64 8}
!11 = !{!"int", !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"llvm.loop.mustprogress"}
!14 = distinct !{!14, !13}


; 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: nofree norecurse nosync nounwind memory(read, inaccessiblemem: none) uwtable
define dso_local ptr @detectCycle(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 %.preheader34

.preheader34:                                     ; preds = %3, %9
  %.020 = phi ptr [ %11, %9 ], [ %0, %3 ]
  %.0 = phi ptr [ %13, %9 ], [ %0, %3 ]
  %7 = getelementptr inbounds i8, ptr %.020, i64 8
  %8 = load ptr, ptr %7, align 8, !tbaa !5
  %.not = icmp eq ptr %8, null
  br i1 %.not, label %.loopexit, label %9

9:                                                ; preds = %.preheader34
  %10 = getelementptr inbounds i8, ptr %8, i64 8
  %11 = load ptr, ptr %10, align 8, !tbaa !5
  %12 = getelementptr inbounds i8, ptr %.0, i64 8
  %13 = load ptr, ptr %12, align 8, !tbaa !5
  %14 = icmp ne ptr %11, %13
  %15 = icmp ne ptr %11, null
  %or.cond = and i1 %15, %14
  br i1 %or.cond, label %.preheader34, label %.critedge, !llvm.loop !11

.critedge:                                        ; preds = %9
  %16 = icmp eq ptr %11, null
  br i1 %16, label %.loopexit, label %.critedge.thread

.critedge.thread:                                 ; preds = %.critedge
  %.phi.trans.insert = getelementptr inbounds i8, ptr %11, i64 8
  %.pre = load ptr, ptr %.phi.trans.insert, align 8, !tbaa !5
  %17 = icmp eq ptr %.pre, null
  br i1 %17, label %.loopexit, label %.preheader

.preheader:                                       ; preds = %.critedge.thread
  %.not2938 = icmp eq ptr %13, %0
  br i1 %.not2938, label %.loopexit, label %.lr.ph

.lr.ph:                                           ; preds = %.preheader, %.lr.ph
  %.240 = phi ptr [ %21, %.lr.ph ], [ %13, %.preheader ]
  %.22239 = phi ptr [ %19, %.lr.ph ], [ %0, %.preheader ]
  %18 = getelementptr inbounds i8, ptr %.22239, i64 8
  %19 = load ptr, ptr %18, align 8, !tbaa !5
  %20 = getelementptr inbounds i8, ptr %.240, i64 8
  %21 = load ptr, ptr %20, align 8, !tbaa !5
  %.not29 = icmp eq ptr %19, %21
  br i1 %.not29, label %.loopexit, label %.lr.ph, !llvm.loop !13

.loopexit:                                        ; preds = %.preheader34, %.lr.ph, %.preheader, %.critedge.thread, %.critedge, %1, %3
  %.124 = phi ptr [ null, %3 ], [ null, %1 ], [ null, %.critedge.thread ], [ null, %.critedge ], [ %0, %.preheader ], [ %19, %.lr.ph ], [ null, %.preheader34 ]
  ret ptr %.124
}

attributes #0 = { nofree norecurse nosync nounwind 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 = !{!"ListNode", !7, i64 0, !10, i64 8}
!7 = !{!"int", !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C/C++ TBAA"}
!10 = !{!"any pointer", !8, i64 0}
!11 = distinct !{!11, !12}
!12 = !{!"llvm.loop.mustprogress"}
!13 = distinct !{!13, !12}


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