; LLVM IR from ritikbanger/Hacktoberfest2022-DSA :: 10. Linked List/c lang/CircularLinkedList (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 }

@start = 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
  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
  %5 = call noalias ptr @malloc(i64 noundef 16) #4
  store ptr %5, ptr %3, align 8, !tbaa !9
  %6 = load i32, ptr %2, align 4, !tbaa !5
  %7 = load ptr, ptr %3, align 8, !tbaa !9
  %8 = getelementptr inbounds %struct.node, ptr %7, i32 0, i32 0
  store i32 %6, ptr %8, align 8, !tbaa !11
  %9 = load ptr, ptr %3, align 8, !tbaa !9
  %10 = getelementptr inbounds %struct.node, ptr %9, i32 0, i32 1
  store ptr null, ptr %10, align 8, !tbaa !13
  %11 = load ptr, ptr @start, align 8, !tbaa !9
  %12 = icmp eq ptr %11, null
  br i1 %12, label %13, label %18

13:                                               ; preds = %1
  %14 = load ptr, ptr %3, align 8, !tbaa !9
  store ptr %14, ptr @start, align 8, !tbaa !9
  %15 = load ptr, ptr @start, align 8, !tbaa !9
  %16 = load ptr, ptr %3, align 8, !tbaa !9
  %17 = getelementptr inbounds %struct.node, ptr %16, i32 0, i32 1
  store ptr %15, ptr %17, align 8, !tbaa !13
  br label %37

18:                                               ; preds = %1
  %19 = load ptr, ptr @start, align 8, !tbaa !9
  store ptr %19, ptr %4, align 8, !tbaa !9
  br label %20

20:                                               ; preds = %26, %18
  %21 = load ptr, ptr %4, align 8, !tbaa !9
  %22 = getelementptr inbounds %struct.node, ptr %21, i32 0, i32 1
  %23 = load ptr, ptr %22, align 8, !tbaa !13
  %24 = load ptr, ptr @start, align 8, !tbaa !9
  %25 = icmp ne ptr %23, %24
  br i1 %25, label %26, label %30

26:                                               ; preds = %20
  %27 = load ptr, ptr %4, align 8, !tbaa !9
  %28 = getelementptr inbounds %struct.node, ptr %27, i32 0, i32 1
  %29 = load ptr, ptr %28, align 8, !tbaa !13
  store ptr %29, ptr %4, align 8, !tbaa !9
  br label %20, !llvm.loop !14

30:                                               ; preds = %20
  %31 = load ptr, ptr %3, align 8, !tbaa !9
  %32 = load ptr, ptr %4, align 8, !tbaa !9
  %33 = getelementptr inbounds %struct.node, ptr %32, i32 0, i32 1
  store ptr %31, ptr %33, align 8, !tbaa !13
  %34 = load ptr, ptr @start, align 8, !tbaa !9
  %35 = load ptr, ptr %3, align 8, !tbaa !9
  %36 = getelementptr inbounds %struct.node, ptr %35, i32 0, i32 1
  store ptr %34, ptr %36, align 8, !tbaa !13
  br label %37

37:                                               ; preds = %30, %13
  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, !6, i64 0}
!12 = !{!"node", !6, i64 0, !10, i64 8}
!13 = !{!12, !10, i64 8}
!14 = distinct !{!14, !15}
!15 = !{!"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

; Function Attrs: nofree nounwind uwtable
define dso_local void @add(i32 noundef %0) local_unnamed_addr #0 {
  %2 = tail call noalias dereferenceable_or_null(16) ptr @malloc(i64 noundef 16) #2
  store i32 %0, ptr %2, align 8, !tbaa !5
  %3 = getelementptr inbounds i8, ptr %2, i64 8
  store ptr null, ptr %3, align 8, !tbaa !11
  %4 = load ptr, ptr @start, align 8, !tbaa !12
  %5 = icmp eq ptr %4, null
  br i1 %5, label %10, label %.preheader

.preheader:                                       ; preds = %1, %.preheader
  %.0 = phi ptr [ %7, %.preheader ], [ %4, %1 ]
  %6 = getelementptr inbounds i8, ptr %.0, i64 8
  %7 = load ptr, ptr %6, align 8, !tbaa !11
  %.not = icmp eq ptr %7, %4
  br i1 %.not, label %8, label %.preheader, !llvm.loop !13

8:                                                ; preds = %.preheader
  %9 = getelementptr inbounds i8, ptr %.0, i64 8
  br label %10

10:                                               ; preds = %1, %8
  %.sink = phi ptr [ %9, %8 ], [ @start, %1 ]
  %storemerge = phi ptr [ %4, %8 ], [ %2, %1 ]
  store ptr %2, ptr %.sink, align 8, !tbaa !12
  store ptr %storemerge, ptr %3, align 8, !tbaa !11
  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}
!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 8}
!12 = !{!10, !10, i64 0}
!13 = distinct !{!13, !14}
!14 = !{!"llvm.loop.mustprogress"}


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