; LLVM IR from ritikbanger/Hacktoberfest2022-DSA :: 10. Linked List/c lang/DoublyLinkedList (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
  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 24) #4
  store ptr %5, ptr %3, align 8, !tbaa !9
  %6 = load ptr, ptr %3, align 8, !tbaa !9
  %7 = getelementptr inbounds %struct.node, ptr %6, i32 0, i32 1
  store ptr null, ptr %7, align 8, !tbaa !11
  %8 = load i32, ptr %2, align 4, !tbaa !5
  %9 = load ptr, ptr %3, align 8, !tbaa !9
  %10 = getelementptr inbounds %struct.node, ptr %9, i32 0, i32 0
  store i32 %8, ptr %10, align 8, !tbaa !13
  %11 = load ptr, ptr %3, align 8, !tbaa !9
  %12 = getelementptr inbounds %struct.node, ptr %11, i32 0, i32 2
  store ptr null, ptr %12, align 8, !tbaa !14
  %13 = load ptr, ptr @start, align 8, !tbaa !9
  %14 = icmp eq ptr %13, null
  br i1 %14, label %15, label %17

15:                                               ; preds = %1
  %16 = load ptr, ptr %3, align 8, !tbaa !9
  store ptr %16, ptr @start, align 8, !tbaa !9
  br label %36

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

19:                                               ; preds = %24, %17
  %20 = load ptr, ptr %4, align 8, !tbaa !9
  %21 = getelementptr inbounds %struct.node, ptr %20, i32 0, i32 2
  %22 = load ptr, ptr %21, align 8, !tbaa !14
  %23 = icmp ne ptr %22, null
  br i1 %23, label %24, label %28

24:                                               ; preds = %19
  %25 = load ptr, ptr %4, align 8, !tbaa !9
  %26 = getelementptr inbounds %struct.node, ptr %25, i32 0, i32 2
  %27 = load ptr, ptr %26, align 8, !tbaa !14
  store ptr %27, ptr %4, align 8, !tbaa !9
  br label %19, !llvm.loop !15

28:                                               ; preds = %19
  %29 = load ptr, ptr %3, align 8, !tbaa !9
  %30 = load ptr, ptr %4, align 8, !tbaa !9
  %31 = getelementptr inbounds %struct.node, ptr %30, i32 0, i32 2
  store ptr %29, ptr %31, align 8, !tbaa !14
  %32 = load ptr, ptr %4, align 8, !tbaa !9
  %33 = load ptr, ptr %3, align 8, !tbaa !9
  %34 = getelementptr inbounds %struct.node, ptr %33, i32 0, i32 1
  store ptr %32, ptr %34, align 8, !tbaa !11
  %35 = load ptr, ptr %3, align 8, !tbaa !9
  store ptr %35, ptr @end, align 8, !tbaa !9
  br label %36

36:                                               ; preds = %28, %15
  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 ptr null, ptr %3, align 8, !tbaa !5
  store i32 %0, ptr %2, align 8, !tbaa !11
  %4 = getelementptr inbounds i8, ptr %2, i64 16
  store ptr null, ptr %4, align 8, !tbaa !12
  %5 = load ptr, ptr @start, align 8, !tbaa !13
  %6 = icmp eq ptr %5, null
  br i1 %6, label %11, label %.preheader

.preheader:                                       ; preds = %1, %.preheader
  %.0 = phi ptr [ %8, %.preheader ], [ %5, %1 ]
  %7 = getelementptr inbounds i8, ptr %.0, i64 16
  %8 = load ptr, ptr %7, align 8, !tbaa !12
  %.not = icmp eq ptr %8, null
  br i1 %.not, label %9, label %.preheader, !llvm.loop !14

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

11:                                               ; preds = %1, %9
  %end.sink = phi ptr [ @end, %9 ], [ @start, %1 ]
  store ptr %2, ptr %end.sink, align 8, !tbaa !13
  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, !10, i64 8}
!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, !7, i64 0}
!12 = !{!6, !10, i64 16}
!13 = !{!10, !10, i64 0}
!14 = distinct !{!14, !15}
!15 = !{!"llvm.loop.mustprogress"}


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