; LLVM IR from mahendramahara/DSA-in-C-Programing :: DOUBLY-LINKED-LIST (LastDeleteDoublyLinkedList)

; 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 }

@head = external dso_local global ptr, align 8
@.str.2 = external hidden unnamed_addr constant [43 x i8], align 1
@.str.3 = external hidden unnamed_addr constant [21 x i8], align 1

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

declare i32 @printf(ptr 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: nounwind uwtable
define dso_local void @deleteFromEnd() #2 {
  %1 = alloca ptr, align 8
  %2 = alloca i32, align 4
  %3 = load ptr, ptr @head, align 8, !tbaa !5
  %4 = icmp eq ptr %3, null
  br i1 %4, label %5, label %7

5:                                                ; preds = %0
  %6 = call i32 (ptr, ...) @printf(ptr noundef @.str.2)
  br label %35

7:                                                ; preds = %0
  call void @llvm.lifetime.start.p0(i64 8, ptr %1) #4
  %8 = load ptr, ptr @head, align 8, !tbaa !5
  store ptr %8, ptr %1, align 8, !tbaa !5
  br label %9

9:                                                ; preds = %14, %7
  %10 = load ptr, ptr %1, align 8, !tbaa !5
  %11 = getelementptr inbounds %struct.Node, ptr %10, i32 0, i32 1
  %12 = load ptr, ptr %11, align 8, !tbaa !9
  %13 = icmp ne ptr %12, null
  br i1 %13, label %14, label %18

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

18:                                               ; preds = %9
  %19 = load ptr, ptr %1, align 8, !tbaa !5
  %20 = getelementptr inbounds %struct.Node, ptr %19, i32 0, i32 2
  %21 = load ptr, ptr %20, align 8, !tbaa !14
  %22 = icmp eq ptr %21, null
  br i1 %22, label %23, label %26

23:                                               ; preds = %18
  %24 = load ptr, ptr %1, align 8, !tbaa !5
  call void @free(ptr noundef %24) #4
  store ptr null, ptr @head, align 8, !tbaa !5
  %25 = call i32 (ptr, ...) @printf(ptr noundef @.str.3)
  store i32 1, ptr %2, align 4
  br label %33

26:                                               ; preds = %18
  %27 = load ptr, ptr %1, align 8, !tbaa !5
  %28 = getelementptr inbounds %struct.Node, ptr %27, i32 0, i32 2
  %29 = load ptr, ptr %28, align 8, !tbaa !14
  %30 = getelementptr inbounds %struct.Node, ptr %29, i32 0, i32 1
  store ptr null, ptr %30, align 8, !tbaa !9
  %31 = load ptr, ptr %1, align 8, !tbaa !5
  call void @free(ptr noundef %31) #4
  %32 = call i32 (ptr, ...) @printf(ptr noundef @.str.3)
  store i32 0, ptr %2, align 4
  br label %33

33:                                               ; preds = %26, %23
  call void @llvm.lifetime.end.p0(i64 8, ptr %1) #4
  %34 = load i32, ptr %2, align 4
  switch i32 %34, label %36 [
    i32 0, label %35
    i32 1, label %35
  ]

35:                                               ; preds = %33, %33, %5
  ret void

36:                                               ; preds = %33
  unreachable
}

; Function Attrs: nounwind
declare void @free(ptr noundef) #3

attributes #0 = { nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #1 = { "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 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 = { 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 #4 = { 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/C++ TBAA"}
!9 = !{!10, !6, i64 8}
!10 = !{!"Node", !11, i64 0, !6, i64 8, !6, i64 16}
!11 = !{!"int", !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"llvm.loop.mustprogress"}
!14 = !{!10, !6, i64 16}


; 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"

@head = external dso_local local_unnamed_addr global ptr, align 8
@.str.2 = external hidden unnamed_addr constant [43 x i8], align 1
@.str.3 = external hidden unnamed_addr constant [21 x i8], align 1

; Function Attrs: nofree nounwind
declare noundef i32 @printf(ptr nocapture noundef readonly, ...) local_unnamed_addr #0

; Function Attrs: nounwind uwtable
define dso_local void @deleteFromEnd() local_unnamed_addr #1 {
  %1 = load ptr, ptr @head, align 8, !tbaa !5
  %2 = icmp eq ptr %1, null
  br i1 %2, label %12, label %.preheader

.preheader:                                       ; preds = %0, %.preheader
  %.0 = phi ptr [ %4, %.preheader ], [ %1, %0 ]
  %3 = getelementptr inbounds i8, ptr %.0, i64 8
  %4 = load ptr, ptr %3, align 8, !tbaa !9
  %.not = icmp eq ptr %4, null
  br i1 %.not, label %5, label %.preheader, !llvm.loop !12

5:                                                ; preds = %.preheader
  %6 = getelementptr inbounds i8, ptr %.0, i64 16
  %7 = load ptr, ptr %6, align 8, !tbaa !14
  %8 = icmp eq ptr %7, null
  br i1 %8, label %9, label %10

9:                                                ; preds = %5
  tail call void @free(ptr noundef nonnull %.0) #3
  store ptr null, ptr @head, align 8, !tbaa !5
  br label %12

10:                                               ; preds = %5
  %11 = getelementptr inbounds i8, ptr %7, i64 8
  store ptr null, ptr %11, align 8, !tbaa !9
  tail call void @free(ptr noundef nonnull %.0) #3
  br label %12

12:                                               ; preds = %0, %9, %10
  %.str.3.sink = phi ptr [ @.str.3, %9 ], [ @.str.3, %10 ], [ @.str.2, %0 ]
  %13 = tail call i32 (ptr, ...) @printf(ptr noundef nonnull dereferenceable(1) %.str.3.sink)
  ret void
}

; Function Attrs: mustprogress nounwind willreturn allockind("free") memory(argmem: readwrite, inaccessiblemem: readwrite)
declare void @free(ptr allocptr nocapture noundef) local_unnamed_addr #2

attributes #0 = { nofree 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 #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 = { mustprogress nounwind willreturn allockind("free") memory(argmem: readwrite, 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 #3 = { 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/C++ TBAA"}
!9 = !{!10, !6, i64 8}
!10 = !{!"Node", !11, i64 0, !6, i64 8, !6, i64 16}
!11 = !{!"int", !7, i64 0}
!12 = distinct !{!12, !13}
!13 = !{!"llvm.loop.mustprogress"}
!14 = !{!10, !6, i64 16}


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