; LLVM IR from bhrigukansra/algorithms-in-C-Cplusplus-Java-Python-JavaScript :: Data Structures/Linked List/C++/SinglyLinkedList.ll (ZN10LinkedList15deletionFromEndEv)

; 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.LinkedList = type { ptr, ptr }
%struct.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: nobuiltin allocsize(0)
declare noundef nonnull ptr @_Znwm(i64 noundef) #1

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

; Function Attrs: nobuiltin nounwind
declare void @_ZdlPvm(ptr noundef, i64 noundef) #2

; Function Attrs: mustprogress uwtable
define dso_local void @_ZN10LinkedList15deletionFromEndEv(ptr noundef nonnull align 8 dereferenceable(16) %0) #3 align 2 {
  %2 = alloca ptr, align 8
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  store ptr %0, ptr %2, align 8, !tbaa !5
  %5 = load ptr, ptr %2, align 8
  call void @llvm.lifetime.start.p0(i64 8, ptr %3) #4
  %6 = call noalias noundef nonnull ptr @_Znwm(i64 noundef 16) #5
  store ptr %6, ptr %3, align 8, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #4
  %7 = call noalias noundef nonnull ptr @_Znwm(i64 noundef 16) #5
  store ptr %7, ptr %4, align 8, !tbaa !5
  %8 = getelementptr inbounds %class.LinkedList, ptr %5, i32 0, i32 0
  %9 = load ptr, ptr %8, align 8, !tbaa !9
  store ptr %9, ptr %3, align 8, !tbaa !5
  br label %10

10:                                               ; preds = %15, %1
  %11 = load ptr, ptr %3, align 8, !tbaa !5
  %12 = getelementptr inbounds %struct.node, ptr %11, i32 0, i32 1
  %13 = load ptr, ptr %12, align 8, !tbaa !11
  %14 = icmp ne ptr %13, null
  br i1 %14, label %15, label %20

15:                                               ; preds = %10
  %16 = load ptr, ptr %3, align 8, !tbaa !5
  store ptr %16, ptr %4, align 8, !tbaa !5
  %17 = load ptr, ptr %3, align 8, !tbaa !5
  %18 = getelementptr inbounds %struct.node, ptr %17, i32 0, i32 1
  %19 = load ptr, ptr %18, align 8, !tbaa !11
  store ptr %19, ptr %3, align 8, !tbaa !5
  br label %10, !llvm.loop !14

20:                                               ; preds = %10
  %21 = load ptr, ptr %4, align 8, !tbaa !5
  %22 = getelementptr inbounds %class.LinkedList, ptr %5, i32 0, i32 1
  store ptr %21, ptr %22, align 8, !tbaa !16
  %23 = load ptr, ptr %4, align 8, !tbaa !5
  %24 = getelementptr inbounds %struct.node, ptr %23, i32 0, i32 1
  store ptr null, ptr %24, align 8, !tbaa !11
  %25 = load ptr, ptr %3, align 8, !tbaa !5
  %26 = icmp eq ptr %25, null
  br i1 %26, label %28, label %27

27:                                               ; preds = %20
  call void @_ZdlPvm(ptr noundef %25, i64 noundef 16) #6
  br label %28

28:                                               ; preds = %27, %20
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #4
  call void @llvm.lifetime.end.p0(i64 8, ptr %3) #4
  ret void
}

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { nobuiltin allocsize(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 = { nobuiltin nounwind "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 = { 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 #4 = { nounwind }
attributes #5 = { builtin allocsize(0) }
attributes #6 = { builtin 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 0}
!10 = !{!"_ZTS10LinkedList", !6, i64 0, !6, i64 8}
!11 = !{!12, !6, i64 8}
!12 = !{!"_ZTS4node", !13, i64 0, !6, i64 8}
!13 = !{!"int", !7, i64 0}
!14 = distinct !{!14, !15}
!15 = !{!"llvm.loop.mustprogress"}
!16 = !{!10, !6, i64 8}


; 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: nobuiltin allocsize(0)
declare noundef nonnull ptr @_Znwm(i64 noundef) local_unnamed_addr #0

; Function Attrs: nobuiltin nounwind
declare void @_ZdlPvm(ptr noundef, i64 noundef) local_unnamed_addr #1

; Function Attrs: mustprogress uwtable
define dso_local void @_ZN10LinkedList15deletionFromEndEv(ptr nocapture noundef nonnull align 8 dereferenceable(16) %0) local_unnamed_addr #2 align 2 {
  %2 = tail call noalias noundef nonnull dereferenceable(16) ptr @_Znwm(i64 noundef 16) #3
  %3 = load ptr, ptr %0, align 8, !tbaa !5
  br label %4

4:                                                ; preds = %4, %1
  %.07 = phi ptr [ %3, %1 ], [ %6, %4 ]
  %.0 = phi ptr [ %2, %1 ], [ %.07, %4 ]
  %5 = getelementptr inbounds i8, ptr %.07, i64 8
  %6 = load ptr, ptr %5, align 8, !tbaa !10
  %.not = icmp eq ptr %6, null
  br i1 %.not, label %7, label %4, !llvm.loop !13

7:                                                ; preds = %4
  %8 = getelementptr inbounds i8, ptr %0, i64 8
  store ptr %.0, ptr %8, align 8, !tbaa !15
  %9 = getelementptr inbounds i8, ptr %.0, i64 8
  store ptr null, ptr %9, align 8, !tbaa !10
  tail call void @_ZdlPvm(ptr noundef nonnull %.07, i64 noundef 16) #4
  ret void
}

attributes #0 = { nobuiltin allocsize(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 = { nobuiltin nounwind "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 = { builtin allocsize(0) }
attributes #4 = { builtin 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, !7, i64 0}
!6 = !{!"_ZTS10LinkedList", !7, i64 0, !7, i64 8}
!7 = !{!"any pointer", !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C++ TBAA"}
!10 = !{!11, !7, i64 8}
!11 = !{!"_ZTS4node", !12, i64 0, !7, i64 8}
!12 = !{!"int", !8, i64 0}
!13 = distinct !{!13, !14}
!14 = !{!"llvm.loop.mustprogress"}
!15 = !{!6, !7, i64 8}


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