; LLVM IR from ritikbanger/Hacktoberfest2022-DSA :: 10. Linked List/c lang/CircularDoublyLinkedList (Deleting)

; 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.node = type { i32, ptr, ptr }

@start = external dso_local global ptr, align 8
@end = external dso_local global ptr, align 8

; 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: nounwind uwtable
define dso_local void @add(i32 noundef %0) #1 {
  %2 = alloca i32, align 4
  %3 = alloca ptr, align 8
  %4 = alloca ptr, align 8
  %5 = alloca ptr, align 8
  store i32 %0, ptr %2, align 4, !tbaa !5
  call void @llvm.lifetime.start.p0(i64 8, ptr %3) #3
  call void @llvm.lifetime.start.p0(i64 8, ptr %4) #3
  call void @llvm.lifetime.start.p0(i64 8, ptr %5) #3
  %6 = call noalias ptr @malloc(i64 noundef 24) #4
  store ptr %6, ptr %3, align 8, !tbaa !9
  %7 = load ptr, ptr %3, align 8, !tbaa !9
  %8 = getelementptr inbounds %struct.node, ptr %7, i32 0, i32 1
  store ptr null, ptr %8, align 8, !tbaa !11
  %9 = load i32, ptr %2, align 4, !tbaa !5
  %10 = load ptr, ptr %3, align 8, !tbaa !9
  %11 = getelementptr inbounds %struct.node, ptr %10, i32 0, i32 0
  store i32 %9, ptr %11, align 8, !tbaa !13
  %12 = load ptr, ptr %3, align 8, !tbaa !9
  %13 = getelementptr inbounds %struct.node, ptr %12, i32 0, i32 2
  store ptr null, ptr %13, align 8, !tbaa !14
  %14 = load ptr, ptr @start, align 8, !tbaa !9
  %15 = icmp eq ptr %14, null
  br i1 %15, label %16, label %25

16:                                               ; preds = %1
  %17 = load ptr, ptr %3, align 8, !tbaa !9
  store ptr %17, ptr @start, align 8, !tbaa !9
  %18 = load ptr, ptr @start, align 8, !tbaa !9
  %19 = load ptr, ptr %3, align 8, !tbaa !9
  %20 = getelementptr inbounds %struct.node, ptr %19, i32 0, i32 2
  store ptr %18, ptr %20, align 8, !tbaa !14
  %21 = load ptr, ptr @start, align 8, !tbaa !9
  %22 = load ptr, ptr %3, align 8, !tbaa !9
  %23 = getelementptr inbounds %struct.node, ptr %22, i32 0, i32 1
  store ptr %21, ptr %23, align 8, !tbaa !11
  %24 = load ptr, ptr %3, align 8, !tbaa !9
  store ptr %24, ptr @end, align 8, !tbaa !9
  br label %52

25:                                               ; preds = %1
  %26 = load ptr, ptr @start, align 8, !tbaa !9
  store ptr %26, ptr %4, align 8, !tbaa !9
  %27 = load ptr, ptr @start, align 8, !tbaa !9
  store ptr %27, ptr %5, align 8, !tbaa !9
  br label %28

28:                                               ; preds = %34, %25
  %29 = load ptr, ptr %4, align 8, !tbaa !9
  %30 = getelementptr inbounds %struct.node, ptr %29, i32 0, i32 2
  %31 = load ptr, ptr %30, align 8, !tbaa !14
  %32 = load ptr, ptr @start, align 8, !tbaa !9
  %33 = icmp ne ptr %31, %32
  br i1 %33, label %34, label %38

34:                                               ; preds = %28
  %35 = load ptr, ptr %4, align 8, !tbaa !9
  %36 = getelementptr inbounds %struct.node, ptr %35, i32 0, i32 2
  %37 = load ptr, ptr %36, align 8, !tbaa !14
  store ptr %37, ptr %4, align 8, !tbaa !9
  br label %28, !llvm.loop !15

38:                                               ; preds = %28
  %39 = load ptr, ptr %3, align 8, !tbaa !9
  %40 = load ptr, ptr %4, align 8, !tbaa !9
  %41 = getelementptr inbounds %struct.node, ptr %40, i32 0, i32 2
  store ptr %39, ptr %41, align 8, !tbaa !14
  %42 = load ptr, ptr %4, align 8, !tbaa !9
  %43 = load ptr, ptr %3, align 8, !tbaa !9
  %44 = getelementptr inbounds %struct.node, ptr %43, i32 0, i32 1
  store ptr %42, ptr %44, align 8, !tbaa !11
  %45 = load ptr, ptr @start, align 8, !tbaa !9
  %46 = load ptr, ptr %3, align 8, !tbaa !9
  %47 = getelementptr inbounds %struct.node, ptr %46, i32 0, i32 2
  store ptr %45, ptr %47, align 8, !tbaa !14
  %48 = load ptr, ptr %3, align 8, !tbaa !9
  %49 = load ptr, ptr %5, align 8, !tbaa !9
  %50 = getelementptr inbounds %struct.node, ptr %49, i32 0, i32 1
  store ptr %48, ptr %50, align 8, !tbaa !11
  %51 = load ptr, ptr %3, align 8, !tbaa !9
  store ptr %51, ptr @end, align 8, !tbaa !9
  br label %52

52:                                               ; preds = %38, %16
  call void @llvm.lifetime.end.p0(i64 8, ptr %5) #3
  call void @llvm.lifetime.end.p0(i64 8, ptr %4) #3
  call void @llvm.lifetime.end.p0(i64 8, ptr %3) #3
  ret void
}

; Function Attrs: nounwind allocsize(0)
declare noalias ptr @malloc(i64 noundef) #2

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { 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 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 #3 = { nounwind }
attributes #4 = { nounwind allocsize(0) }

!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 = !{!"int", !7, i64 0}
!7 = !{!"omnipotent char", !8, i64 0}
!8 = !{!"Simple C/C++ TBAA"}
!9 = !{!10, !10, i64 0}
!10 = !{!"any pointer", !7, i64 0}
!11 = !{!12, !10, i64 8}
!12 = !{!"node", !6, i64 0, !10, i64 8, !10, i64 16}
!13 = !{!12, !6, i64 0}
!14 = !{!12, !10, i64 16}
!15 = distinct !{!15, !16}
!16 = !{!"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"

@start = external dso_local local_unnamed_addr global ptr, align 8
@end = external dso_local local_unnamed_addr global ptr, align 8

; Function Attrs: nofree nounwind uwtable
define dso_local void @add(i32 noundef %0) local_unnamed_addr #0 {
  %2 = tail call noalias dereferenceable_or_null(24) ptr @malloc(i64 noundef 24) #2
  %3 = getelementptr inbounds i8, ptr %2, i64 8
  store i32 %0, ptr %2, align 8, !tbaa !5
  %4 = getelementptr inbounds i8, ptr %2, i64 16
  store ptr null, ptr %4, align 8, !tbaa !11
  %5 = load ptr, ptr @start, align 8, !tbaa !12
  %6 = icmp eq ptr %5, null
  br i1 %6, label %7, label %.preheader

7:                                                ; preds = %1
  store ptr %2, ptr @start, align 8, !tbaa !12
  store ptr %2, ptr %4, align 8, !tbaa !11
  br label %13

.preheader:                                       ; preds = %1, %.preheader
  %.0 = phi ptr [ %9, %.preheader ], [ %5, %1 ]
  %8 = getelementptr inbounds i8, ptr %.0, i64 16
  %9 = load ptr, ptr %8, align 8, !tbaa !11
  %.not = icmp eq ptr %9, %5
  br i1 %.not, label %10, label %.preheader, !llvm.loop !13

10:                                               ; preds = %.preheader
  %11 = getelementptr inbounds i8, ptr %.0, i64 16
  store ptr %2, ptr %11, align 8, !tbaa !11
  store ptr %.0, ptr %3, align 8, !tbaa !15
  store ptr %5, ptr %4, align 8, !tbaa !11
  %12 = getelementptr inbounds i8, ptr %5, i64 8
  br label %13

13:                                               ; preds = %10, %7
  %.sink = phi ptr [ %12, %10 ], [ %3, %7 ]
  store ptr %2, ptr %.sink, align 8, !tbaa !15
  store ptr %2, ptr @end, align 8, !tbaa !12
  ret void
}

; Function Attrs: mustprogress nofree nounwind willreturn allockind("alloc,uninitialized") allocsize(0) memory(inaccessiblemem: readwrite)
declare noalias noundef ptr @malloc(i64 noundef) local_unnamed_addr #1

attributes #0 = { nofree 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 = { mustprogress nofree nounwind willreturn allockind("alloc,uninitialized") allocsize(0) memory(inaccessiblemem: readwrite) "alloc-family"="malloc" "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 allocsize(0) }

!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 = !{!"node", !7, i64 0, !10, i64 8, !10, i64 16}
!7 = !{!"int", !8, i64 0}
!8 = !{!"omnipotent char", !9, i64 0}
!9 = !{!"Simple C/C++ TBAA"}
!10 = !{!"any pointer", !8, i64 0}
!11 = !{!6, !10, i64 16}
!12 = !{!10, !10, i64 0}
!13 = distinct !{!13, !14}
!14 = !{!"llvm.loop.mustprogress"}
!15 = !{!6, !10, i64 8}


; Effective O3 passes: DSEPass,EarlyCSEPass,GVNPass,GlobalOptPass,InferFunctionAttrsPass,InstCombinePass,InstSimplifyPass,LCSSAPass,LICMPass,LoopSimplifyPass,LoopUnrollPass,PostOrderFunctionAttrsPass,SROAPass,SimplifyCFGPass,TailCallElimPass