; LLVM IR from ritikbanger/Hacktoberfest2022-DSA :: 10. Linked List/cpp/Checking if a linked list is Palindrome.ll (Z9reverseLLP4Node)

; 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: mustprogress nounwind uwtable
define dso_local noundef ptr @_Z9reverseLLP4Node(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
  %7 = alloca ptr, align 8
  store ptr %0, ptr %3, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #2
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #2
  %8 = load ptr, ptr %3, align 8, !tbaa !5
  %9 = icmp eq ptr %8, null
  br i1 %9, label %10, label %12

10:                                               ; preds = %1
  %11 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %11, ptr %2, align 8
  store i32 1, ptr %6, align 4
  br label %34

12:                                               ; preds = %1
  %13 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %13, ptr %4, align 8, !tbaa !5
  %14 = load ptr, ptr %4, align 8, !tbaa !5
  %15 = getelementptr inbounds %class.Node, ptr %14, i32 0, i32 1
  %16 = load ptr, ptr %15, align 8, !tbaa !9
  store ptr %16, ptr %5, align 8, !tbaa !5
  br label %17

17:                                               ; preds = %20, %12
  %18 = load ptr, ptr %5, align 8, !tbaa !5
  %19 = icmp ne ptr %18, null
  br i1 %19, label %20, label %29

20:                                               ; preds = %17
  call void @llvm.lifetime.start.p0(i64 8, ptr %7) #2
  %21 = load ptr, ptr %5, align 8, !tbaa !5
  %22 = getelementptr inbounds %class.Node, ptr %21, i32 0, i32 1
  %23 = load ptr, ptr %22, align 8, !tbaa !9
  store ptr %23, ptr %7, align 8, !tbaa !5
  %24 = load ptr, ptr %4, align 8, !tbaa !5
  %25 = load ptr, ptr %5, align 8, !tbaa !5
  %26 = getelementptr inbounds %class.Node, ptr %25, i32 0, i32 1
  store ptr %24, ptr %26, align 8, !tbaa !9
  %27 = load ptr, ptr %5, align 8, !tbaa !5
  store ptr %27, ptr %4, align 8, !tbaa !5
  %28 = load ptr, ptr %7, align 8, !tbaa !5
  store ptr %28, ptr %5, align 8, !tbaa !5
  call void @llvm.lifetime.end.p0(i64 8, ptr %7) #2
  br label %17, !llvm.loop !12

29:                                               ; preds = %17
  %30 = load ptr, ptr %3, align 8, !tbaa !5
  %31 = getelementptr inbounds %class.Node, ptr %30, i32 0, i32 1
  store ptr null, ptr %31, align 8, !tbaa !9
  %32 = load ptr, ptr %4, align 8, !tbaa !5
  store ptr %32, ptr %3, align 8, !tbaa !5
  %33 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %33, ptr %2, align 8
  store i32 1, ptr %6, align 4
  br label %34

34:                                               ; preds = %29, %10
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #2
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #2
  %35 = load ptr, ptr %2, align 8
  ret ptr %35
}

; 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 = { 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 #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++ 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 memory(readwrite, inaccessiblemem: none) uwtable
define dso_local noundef ptr @_Z9reverseLLP4Node(ptr noundef %0) local_unnamed_addr #0 {
  %2 = icmp eq ptr %0, null
  br i1 %2, label %8, label %3

3:                                                ; preds = %1
  %4 = getelementptr inbounds i8, ptr %0, i64 8
  %5 = load ptr, ptr %4, align 8, !tbaa !5
  %.not17 = icmp eq ptr %5, null
  br i1 %.not17, label %._crit_edge, label %.lr.ph

.lr.ph:                                           ; preds = %3, %.lr.ph
  %.01419 = phi ptr [ %7, %.lr.ph ], [ %5, %3 ]
  %.01518 = phi ptr [ %.01419, %.lr.ph ], [ %0, %3 ]
  %6 = getelementptr inbounds i8, ptr %.01419, i64 8
  %7 = load ptr, ptr %6, align 8, !tbaa !5
  store ptr %.01518, ptr %6, align 8, !tbaa !5
  %.not = icmp eq ptr %7, null
  br i1 %.not, label %._crit_edge, label %.lr.ph, !llvm.loop !11

._crit_edge:                                      ; preds = %.lr.ph, %3
  %.015.lcssa = phi ptr [ %0, %3 ], [ %.01419, %.lr.ph ]
  store ptr null, ptr %4, align 8, !tbaa !5
  br label %8

8:                                                ; preds = %1, %._crit_edge
  %.0 = phi ptr [ %.015.lcssa, %._crit_edge ], [ null, %1 ]
  ret ptr %.0
}

attributes #0 = { mustprogress nofree norecurse nosync nounwind memory(readwrite, 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}
!11 = distinct !{!11, !12}
!12 = !{!"llvm.loop.mustprogress"}


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